|1-1||2:00:00 PM||Seokhun KIM||One step pyro-synthesis process of nanostructured Li3V2(PO4)3/C cathode for rechargeable Li-ion batteries|
A monoclinic Li3V2(PO4)/C (LVP/C) with nanostructured morphology was synthesized via a one-step pyro-synthesis, for use as cathode material in rechargeable Li-ion batteries. Highly crystalline LVP/C nanoparticles can be obtained without additional heat treatment. The structural properties and morphology of the sample were studied using various analyses, including high resolution powder X-ray diffraction (HRPD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The LVP/C cathode exhibited initial discharge capacities of 139 and 190.3 mA g-1 within the potential windows of 3 - 4.3 V and 3 - 4.8 V, respectively. These results
indicate that the formation of nanosized particles and the presence of amorphous carbon layer influence the electrochemical properties LVP/C electrode. Specifically, the present pyro-synthesis strategy facilitates the production of LVP cathode materials with improved cyclability and rate capability under very short reaction time.
Seokhun Kim, Jinju Song, Balaji Sambandam, Sungjin Kim, Jeonggeun Jo, Sohyun Park, Sora Baek, Jaekook Kim
|Ph. D. course|
|1-2||2:04:30 PM||Jeonggeun JO|
Synthesis of nanosized-LiMn2O4/C by one-pot pyrosynthesis method to enhance electrochemical properties of Li-ion batteries
A highly crystalline carbon coated LiMn2O4 with nano sized particle was synthesized via a one-pot polyol assisted pyro synthesis, for use as cathode material in rechargeable Li-ion batteries. The structural properties were studied using various analysis, including high resolution powder X-ray diffraction(HRPD), X-ray absorption fine structure(XAFS) Furthermore, a uniform carbon coating on the LiMn2O4 nanoparticles was observed by transmission electron microscopy(TEM). The LiMn2O4/C cathode demonstrates excellent electrochemical properties (86% and 77.5% cycle stability, 79% and 36% high rate capabilities within the potential windows of 3.3~4.3V and 2.5~4.3V). These results were attributed to the inclusion of the nanosized particles and the presence of amorphous carbon layer in the present cathode by synthesized a simple pyro synthetic method.
|J.G. Jo, S. J. Kim, S.H. Kim, S.H. Park, J. Kim||Ph. D. course|
|1-3||2:09:00 PM||Yashabanta N. SINGHBABU|
Aeschynomene aspera plant derived reduced graphene oxide: A suitable matrix for high sulfur loading towards Li-S battery cathode
The increase in energy usages brings concern about environmental pollution associated with the overdependence on fossil fuel. Hence, alternative renewable energy sources are the next options. The wind and solar energies are sporadic. So it is paramount to store these energies efficiently and economically. Rechargeable batteries are one of the most convenient option to store electrical energy. The development of next generation batteries is of primary focus to power the portable electronics, electric vehicle and grid energy storage. Li-S battery looks impressive in this regard owing to its high theoretical capacity of 1672 mAhg-1. However, Li-S battery encounter serious issues such as insulating nature of sulfur, dissolution of polysulfides and tremendous volume expansion. Fabrication of S-carbon composite is one of the simple solution. Among different carbon material graphene derivatives with outstanding properties stands unique. However, the carbon sources used and the synthesis protocol both for graphene and its derivative are complex, multi-step and involve toxic chemicals.Therefore, it is important to search a sustainable carbon source and develop a simple, scalable, green methodology to synthesize graphene derivative. This study aims towards green synthesis of RGO from Aeschynomene aspera in a single step and utilize the as synthesized RGO as a composite material with sulfur to fabricate cathode for Li-S battery followed by its performance evaluation.
|Yashabanta N. Singhbabu, Chan-Jin Park||Post-doctoral researcher|
|1-4||2:13:30 PM||Han-Byeol KIM||Vanadium nitride/carbon nanofibers composite membrane as an interlayer for high-performance lithium-sulfur batteries|
In this work, we fabricated carbon nanofibers(CNF) and vanadium nitride/carbon nanofibers(VN/CNF) by electrospinning method and applied as a interlayer which sandwiched between cathode and separator. The morphology and chemical composition of electrospun CNF and VN/CNF were characterized by SEM, TEM, and XPS, respectively. The Li-S cell with CNF and VN/CNF interlayer exhibited good electrochemical performance in terms of specific capacity, cyclability, and rate capability. To investigate role of interlayer, surface of cycled sulfur cathode and interlayer was analyzed by SEM. Also, for comparison of polysulfide adsorption ability between CNF and VN/CNF, the polysulfide adsorption test was performed using Li2S6 in DOL/DME solution. As a result, Li-S cell which employed CNF and VN/CNF interlayer show high initial discharge capacity of 990 and 1667 mAh g-1 at the rate of 0.5C with 98.81% and 97.57% average Coulombic efficiency during 400 cycles, respectively. These results proved to be due to the effects of interlayer by serving additional deposition sites on the sulfur cathode and reutilizing captured polysulfide on the interlayer. Particularly, at the result from polysulfide adsorption test, owing to the polysulfide adsorption ability of VN, it was observed that VN/CNF can capture more polysulfide than CNF. Furthermore, due to the catalytic effect of VN, VN/CNF can assist in the utilization of the captured active material, resulting in the highest specific capacity.
|Han-Byeol Kim, Chan-Jin Park||Master course|
|1-5||2:18:00 PM||Moonsu SONG||Metal organic framework-combustion: NiO nanoparticles for lithium ion batteries having excellent anode property|
NiO nanoparticles with an average particle size of 30 nm synthesized using MOF-C (one-pot metal-organic framework-combustion), for use as an anode material in rechargeable lithium ion batteries (LIBs). The structural and electronic properties of these nanoparticles are studied using various techniques, including powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and N 2 adsorption/desorption stud- ies. The as-synthesized NiO nanoparticles sustained reversible stable capacities of 748 and 410 mAh/g at applied current densities of 500 and 1000 mA/g, respectively, after 100 cycles. Furthermore, the anode displays a notable rate capability, achieving a stable capacity of ∼200 mAh/g at a high current density of 10 A/g. These results indicate that the size of the NiO nanoparticles and their high surface area influence their electrochemical properties. Specifically, this combustion strategy is clearly favorable for improving the cyclability and rate capability of various metal oxides in rechargeable battery electrodes.
Jeonggeun Jo, Vinod Mathew, Seokhun Kim, Sohyun Park, Seulgi Lee, Moonsu Song, Seungmi Han, Jaekook Kim
|1-6||2:22:30 PM||Seulgi LEE||MnS composites with N-doped carbon as anode materials for lithium-ion batteries|
MnS composites with nitrogen-doped carbon were designed as anode materials for lithium-ion batteries. A facile two-step method was developed to synthesize the composites. The MnS composites were prepared by polyol process and heated the precursor at appropriate temperatures for 2 hours in a Ar atmosphere. The microstructure and morphology were carefully investigated by means of field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and powder X-ray diffraction (XRD). As anode materials, the MnS composites exhibit large reversible capacity, excellent cyclic stability and high rate capability.
|Seulgi Lee, Sungjin Kim, Jaekook Kim||Integrated course|
|1-7||2:27:00 PM||Soumyadeep SHINHA||Atomic layer deposited zinc oxysulfide thin film as an anode material in Li-ion battery|
In the recent time, the sustainable and eco-friendly rechargeable energy sources are in high demand to obtain the global environmental pollution free energy storage. Therefore, the choice of Li-ion batteries is not only the power source of the portable electronic gadgets but also for the next-generation electric vehicles. This factor eventually leads to the investigation of new electrode materials to maximize the energy/power density per unit mass as well as per unit area or volume of the active materials. In this study, zinc oxysulfide (ZnOS) thin films on stainless steel (SS) current collector were deposited by ALD which were directly used as an anode material in Li-ion battery without any carbon and binder. The electrochemical performance of the anode material was investigated by cyclic voltammetry (CV) measurements against Li in a half cell configuration which showed prominent redox-peaks during both cathodic and anodic process. A stable discharge capacity of above 500 mAh/g was obtained at 100th cycle during the charge-discharge cycling performance of this electrode at a high current density of 1 A/g which was significantly higher than the pristine ZnO and ZnS. Thus, this work can be presented as a typical approach to study the electrochemical responses of a double-anion compound active material which can be easily obtained with a desired stoichiometry with high precision by ALD.
|Soumyadeep Sinha and Jaeyeong Heo||Post-doctoral researcher|
|1-8||2:31:30 PM||Sohyun PARK||Sodium manganese oxide electrodes accompanying self-ion exchange for lithium/sodium hybrid ion batteries|
P2-structure sodium manganese oxide is synthesized by a facile reduction reaction. We provide new data on the direct use of sodium manganese oxide instead of lithium analogues as a low-cost electrode for lithium/sodium hybrid ion batteries after an ion-exchange process. Ion exchange occurs in sodium manganese oxide through the electrolyte during cell stabilization, as observed by X-ray diffraction analysis. The self ion-exchanged material delivers a high discharge capacity of 195 mA h g1 and a stable plateau at 3.0 V for 50 cycles with stable cyclability. In-situ X-ray diffraction and ex-situ X-ray absorption near edge structure studies also confirm reversible redox reactions and stable structural changes. The ex-situ inductively coupled plasma atomic emission spectroscopy analysis verifies that residual sodium ions in the structure act as pillars during cycling.
|Sohyun Park, Jinju Song, Jihyeon Gim, Jaekook Kim||Ph. D. course|
|1-9||2:36:00 PM||Sunhyeon PARK||Monoclinic-orthorhombic NLVP/C composite cathode for Na+/Li+ hybrid-ion batteries|
In this paper, we report a new monoclinic-orthorhombic Na1.1Li2.0V2(PO4)3/C (NLVP/ C) composite cathode synthesized from monoclinic LVP via a soft ion-exchange reaction for use in Na+ /Li+ hybrid-ion batteries. XRD, thermal studies, and electrochemical data confirm room temperature stabilization of the monoclinic-orthorhombic NLVP/C composite phase. The cathode delivered initial discharge capacities of 115 and 145 mAh g−1 at a current density of 7.14 mA g−1 in the 2.5−4 and 2.5−4.6 V vs Na/Na+ potential windows, respectively. In the lower potential window (2.5−4 V), the composite electrode demonstrated a two-step voltage plateau during the insertion and extraction of Na+ /Li+ ions. Corresponding in situ synchrotron XRD patterns recorded during initial electrochemical cycling clearly indicate a series of two-phase transitions and confirm the structural stability of the NLVP/C composite cathode during insertion and extraction of the hybrid ions. Under extended cycling, excessive storage of Na ions resulted in the gradual transformation to the orthorhombic NLVP/C symmetry due to the occupancy of Na ions in the available orthorhombic sites. The present study thus showcases the feasibility of using a soft ion-exchange reaction at 150 °C to facilitate the formation of composite phases suitable for rechargeable hybrid-ion battery applications.
Sunhyeon Park, Sungjin Kim, Jeonggeun Jo, Seulgi Lee, Duong Tung Pham and , Woong Park, Seungmi Han Jaekook Kim*
|Cancelled||1-10||2:40:30 PM||Jun LEE||Synthesis of Na3V2(PO4)3 as cathode for sodium–ion batteries via polyol process|
In this study, chromium was doped in Na3V2(PO4)3(NVP), which is an cathode material for Sodium ion battery. The effect of Cr substitution on the crystal structure, morphology and electrochemical performance of NVP is investigated based on rational design and synthesis optimization. Samples with stoichiometric proportions of Na3V2-xCrx(PO4)3 (x=0, 0.1, 0.2, 0.3, 0.4) were prepared by adding Chromium acetate in the starting materials of NVP. As a synthesis method, Pyro-synthesis which is low cost method using the solvent and very simple is used for Sodium-ion batteries. The X-ray diffraction(XRD) showed that the Cr-doped NVP had the same rhombohedral structure as the pure NVP. The purity and crystallinity of Cr-doped samples were confirmed from the XRD patterns. Na3V2-xCrx(PO4)3 shows electrochemical cyclability and high rate cycling performance compared to pure Na3V2(PO4)3. Cr 0.4 doped-NVP exhibits distinct locality among the other samples(77.78mAhg-1 at 20C). Na+ insertion/extraction mechanisms were monitored by in-situ X- ray diffraction. in-situ XRD results confirms the structural stability of Cr 0.4 doped-NVP is stronger than Pure-NVP. The improved electrochemical performance of Cr-doped NVP cathode materials were attributed to the above factors.
|Jun Lee, Jinju Song, Sohyun Park, Jaekook Kim||Ph. D. course|
|1-11||2:45:00 PM||Seyeon KIM|
Synthesis and characteristic of Na3V2(PO4)2F3 as cathode materials from various solvent by polyol process for sodium-ion batteries
The Na3V2(PO4)2F3 (NVPF) have attracted much attention as promising new cathode materials for rechargeable Na-ion batteries due to its low-cost, good structure stability, and competitive electrochemical properties. The carbon coated pure NVPF was synthesized by Conventional Polyol Process (CPP) using various solvents. The X-ray diffraction patterns of all samples were indexed on the basis of tetragonal structure. The SEM analysis confirmed that it was synthesized as uniform nanoparticles. In addition, TEM and Raman spectroscopy analysis confirmed that a thin conductive carbon was coated on the particles. The electrochemical results of NVPF (synthesized by DEG solvent) showed high initial discharge capacity (0.1C – 114mAh/g) and excellent high rate characteristics (50C - 81mAh/g) among the cathode materials of sodium ion batteries.
|Seyeon Kim, Sohyun Park, Jaekook Kim||Master course|
|2-1||3:00:00 PM||Woong PARK||Improved electrochemical properties of NASICON Type Na3V2(PO4)3 using pyro-synthesis for sodium-ion batteries|
We report on carbon coated NASICON-type Na3V2(PO4)3-Fe2P (NVP-FP/C) composite cathode are successfully synthesized by polyol-based pyro synthesis for Na-ion battery applications. The X-ray diffractions patterns were well indexed NASICON structure of Na3V2(PO4)3 and hexagonal structure of Fe2P, respectively, in the NVP-FP/C composite. The high-rate electrochemical performance of NVP-FP/C composite electrode shows higher discharge capacities (93.70mAhg-1 at 10.9C and 79.94mAhg-1 at 33.2C) than the NVP/C electrode (55.4mAhg-1 ate 10.9C and 4.2mAhg-1 at 33.2C) and the NVP-FP/C electrode capacity retained 94% of the initial capacity even after 1800cycles at 20C. It seems that Fe2P phase and nanoscale NVP particles have influenced to a better performance in terms of electrical conductivity of the composite. Therefore, reveals that NVP-FP/C nanocomposite is a suitable candidate for NIB having a nature of high power, energy and density.
|Woong Park, Sohyun Park, Jaekook Kim||Master course|
|2-2||3:04:30 PM||Tran Thi Huyen TRAN||Mixed-ionic-electronic conduction characteristics of Na3V2(PO4)3 cathode material|
Na3V2(PO4)3 (NVP) powder was successfully prepared by solid state reaction and sintered into bulk disks. DSC between -50C and 300C confirmed the phase transitions aa/b/b'/g. To understand mixed-ionic-electronic conduction in Na3V2(PO4)3 (NVP), different electrodes of Ag, Na, Na|Na+(liq.) were applied. The latter two electrodes were installed in coin cells. Considerable ionic conductivity is evidenced in the electrode polarization behavior with Ag electrode for as-prepared NVP. The variation of conductivity with the structural order-disorder phase transitions is also indicated, similarly as recently observed in Na3Sc2(PO4)3 [Moon et al, SSI 289 (2016) 57]. With Na metal electrode high conductivity with a very low activation energy was observed. With ionic liquid electrode impedance becomes much larger and more strongly activated. Different AC behavior with electrode material should be related to the mixed-ionic-electronic conduction in NVP.
Tran Thi Huyen Tran, Duong Tung Pham, Thuy Linh Pham, Jinju Song, Sohyun Park, Jaekook Kim, Jong-Sook Lee
|Ph. D. course|
|2-3||3:09:00 PM||Duong Tung PHAM||A zero fading sodium ion battery: High compatibility microspherical patronite in ether-based electrolyte|
The state-of-the-art vanadium sulfide VS4, a linear-chain compound of disulfide anions [S2]2– with vanadium atoms, has proved to have high potential in the field of secondary batteries due to its unique properties. Possessing qualities of a remarkable theoretical capacity, high electrical conductivity, natural bundance, and environmental friendliness, VS4 is determined to be a significant candidate for new high-energy storage systems. However, the fundamental drawbacks of capacity-fading issues, such as structure collapse or activematerial loss during repeated cycling, critically limit the practical applications of VS4. Overcoming those obstacles, the present work used a design strategy to develop a VS4 electrode with a unique secondary morphology and utilize it in combination with a specific choice of an ether-based electrolyte for sodium ion batteries. This pristine VS4 displayed exceptional rate performance with excellent and stable cycling ability. An important finding in this study is the presence of a highly protective solid electrolyte interphase layer along the surface of the primary particle, which limits the polysulfide dissolution and hence preserves the active material during the reaction with sodium, as observed using ex-situ potentio-electrochemical impedance spectroscopy examinations. The detailed complex redox process of VS4/Na was also elucidated by ex situ X-ray photoelectron spectroscopy.
Duong Tung Pham, Balaji Sambandam, Sungjin Kim, Jeonggeun Jo, Seokhun Kim, Sohyun Park, Vinod Mathew, Yang-Kook Sun, Kwangho Kim, Jaekook Kim
|2-4||3:13:30 PM||Trang Thi VU||High rate performance in rational design NiS2 anode material for SIBs|
The sulfur-rich NiS2 is a promising anode material for sodium ion batteries (SIBs). However, the volume expansion and low intrinsic conductivity are the demerits make the Na+ storage performance not high as their theoretical capacity. To date, we introduce a rational design for the preparation of nanoparticles NiS2 embedded into carbon matrix by successive carbonization and sulfidation. The in-situ combination captured an increased capacity of 818 mAh/g at 0.1 A/g after 50 cycles and an excellent cycle stability of 792 aAh/g at 0.5 A/g after more than 400 cycles using solely one cell even at 1.0 A/g, the cell still remained excellent cyclability of 714 mAh/g at 1.0 A/g. More interestingly, the NiS2 delivered the ultra-high average reversibile capacity of 440 mAh/g was maintained at very high current density of 5.0 A/g . Eventually, the material characterization and electrochemical behaviors were investigated to exhibit the detailed complex redox mechanisms during cycling.
|Trang Thi Vu, Duong Tung Pham, Jeonggeun Jo, Vinod Mathew, Jaekook Kim||Ph. D. course|
|2-5||3:18:00 PM||Seunggyeong LEE||Amorphous MFePO4 (M = Li/Na/K) : Synthesis and characterization for cathode Materials of secondary batteries|
MFePO4 was synthesized by ion exchange reaction for secondary batteries. XRD confirmed that MFePO4 had an amorphous structure and predicted the synthesis mechanism through Raman and XPS analysis. Electrochemical test results showed excellent cycling stability not even Li+ and Na+ ion but also K+ ion inserted in MFePO4 (coulonbic efficiency 99.42%, 99.99%, 97.42% after 90th cycle). Analyzed the mechanism during charging and discharging through Ex-situ XPS.
|Sungjin Kim, Jeonggeun Jo, Seulgi Lee, Pham Tung Duong, Dimas Yunianto Putro, Jaekook Kim||Master course|
|2-6||3:22:30 PM||Rakesh VERMA|
Synthesis and electrochemical characterization of tin phosphorus based alloy material for next generation K-Ion battery anode
Lithium-ion batteries (LIBs) have been successfully used to power small portable electronic devices owing to their high energy density. However, it is still debatable whether mineral resources for LIBs can meet the increasing demands associated with the expansion of LIBs into the area of large-scale energy storage systems. Therefore, scientists are searching for alternatives to LIBs, which are based on earth-abundant elements including Na, K, and Mg. Among them, potassium-ion batteries (PIBs) appear to be a more promising candidate due to an abundance of K: ~900 times higher than that of Li. Thus, PIBs can possibly deliver a higher cell potential compared to SIBs and LIBs. Alloy based materials have shown a potential as anode materials for PIBs.
In the present work, SnP3/C nanocomposite as a potential anode material for PIBs was synthesized via a facile and cost-effective high energy ball-milling technique. The phase purity, crystal structure, and morphology of the synthesized materials were characterized by XRD, SEM, and TEM. Furthermore, the electrochemical characteristics of the SnP3/C electrodes were investigated through cyclic voltammetry, electrochemical impedance measurement, and cyclic charge-discharge tests. Lastly, we further demonstrate the practical feasibility of K-ion batteries by constructing full cells.
|Rakesh Verma, Chan-Jin Park||Post-doctoral researcher|
|2-7||3:27:00 PM||Hyeong-Seo KI||Tin composite anode materials toward advanced potassium-ion batteries|
In this study, the interconnected porous Sb-carbon nanocomposite (Sb-C) for was synthesized through simple citrate gel carbothermal reduction route with citric acid as a chealating agent and carbon source as well. The gel complex was calcined at different temperatures in N2 atmosphere for the carbothermal reduction affecting porosity of the Sb-C composites. The crystal structure, morphology and carbon content of the Sb-C composite were investigated by XRD, SEM, and TGA. Furthermore, K/ 0.75M KPF¬6 in EC+DEC/ Sb-C composite coin cells (CR2032) were assembled in Ar filled glove box. Effect of the calcination temperature on the electrochemical performance of the Sb-C composite has also been investigated within a potential range from 0.01 V to 2.5 V.
|Hyeong-Seo Ki, Chan-Jin Park||Master course|
|2-8||3:31:30 PM||Islam SAIFUL||New rechargeable battery based on zinc anode and NaV6O15 nanorod cathode|
We explore NaV6O15 nanorod electrode is prepared by sol-gel method for aqueous rechargeable zinc-ion batteries applications. The Zn/NaV6O15 cell provides high capacity of 427 mAh g-1 at 50 mA g-1 current density.
Saiful Islam, Muhamma Hilmy Alfaruqi , Balaji Sambandam, Dimas Yunianto Putro, Sungjin Kim, Jeonggeun Jo, Seokhun Kim, Vinod Mathew, Jaekook Kim*
|2-9||3:36:00 PM||Sambandam BALAJI||Consequences in aqueous rechargeable Zn-ion storage|
1D nanorods of the layered material K2V6O16 2.7H2O (KVO) are
implemented for the first time as cathode materials in secondary
aqueous rechargeable Zn-ion batteries (ARZIBs) and exhibit excellent
electrochemical Zn storage properties. This cathode material delivers
a reversible capacity of 296 mA h/g over 100 cycles. At current
densities of 1000, 3000, and 5000 mA/g for 700 cycles, the electrode displays reversible capacities of 223, 177, and 138 mA h/g, for
approximately 170, 300, and 230 cycles, respectively. Though it shows good stability at high current densities, the electrode suffers stability at low current densities, a most common issue in aqueous batteries. In addition, zinc basic sulfate (ZBS), an insulating layered material formed by a parasitic reaction in all ARZIBs in mild acidic ZnSO4 electrolyte, may alter the electrochemical properties, the origin has not yet discussed properly in the literature. This work investigates the consequences in Zn aqueous battery by this parasitic reaction, which is originated by electrolyte pH change during reaction. It is rather important to analysis the factors that affecting the electrode stability than to represent the electrochemical performance at high current densities before the loss in active mass at the cathode. This defiantly improve the scenario to support the risk-free and cost-effective technology with improve high energy and power densities for energy storage.
Balaji Sambandam, Sungjin Kim, Jeonggeun Jo, Seokhun Kim, Sohyun Park, June Lee, D T Pham, V Soundhararajan and Jaekook Kim
|2-10||3:40:30 PM||Dimas PUTRO||Hush-like α-MnO2 by one step hydrothermal synthesis as high capacity cathode for aqueous zinc ion battery|
Tunnel-type α-MnO2 with a hush-like morphology prepared via a one-step hydrothermal synthesis method at 120 °C for use in aqueous zinc ion battery (ZIB) system. Cathode material of α-MnO2 assembled in liquid and gel electrolyte. Di water solution was used for liquid electrolyte and gelatin for gel electrolyte. When tested in a zinc cell, the α-MnO2 in liquid electrolyte exhibited a high first discharge capacity of 288.8 mAh g-1 at 50 mA g-1 current density and it was higher than gel electrolyte. Furthermore, we studied about water and sulfate based electrolyte for performance contribution in an aqueous system. And then, we proposed about electrochemical measurement at different scan rate to investigate capacitive contribution analysis for both samples in different electrolyte. This study may give understanding about pseudocapacitance that can dominate the charge/discharge process.
|Dimas Yunianto Putro, Muhammad Hilmy Alfaruqi, Saiful Islam, Vinod Mathew, Jaekook Kim||Integrated course|
|2-11||3:45:00 PM||Shubham CHATTERJEE||A superior anode in lithium-ion battery of porous TiN nanoparticles embedded in a N-doped carbon composite|
A porous TiN/N-doped carbon composite electrode prepared via a metal–organic framework strategy exhibited high reversible lithium specific capacity (561 mA h g−1 at 50 mA g−1), excellent rate capability (281 mA h g−1 at 2 A g−1), and good cycle stability (310 mA h g−1 at 2 A g−1 for 400 cycles).
|Shubham Chatterjee, Sungjin Kim, Sohyun Park, Jun Lee, Saiful Islam, Jaekook Kim||Integrated course|
|3-1||4:00:00 PM||Jeong-Seon LEE||Blended cathode materials for all-solid-state Li-ion batteries|
In this article, we report the effects of blended cathode materials in all solid-state lithium-ion batteries (ASLBs) with oxide-based inorganic-organic-hybrid electrolytes. A high capacity Ni-rich cathode material was used for high energy density in an ASLB, and LiFePO4, with its robust olivine structure, was added to compensate for the degradation of the Ni-rich cathode material during cycling. In case of the blended cathode, the shortcomings of the parent material can be minimized by blending two cathode materials, and the blending ratio can be tailored to produce stable high energy and power densities. For these reasons, the structure, cycling stability, and rate performance of the blended LiNi0.7Co0.15Mn0.15O2/LiFePO4 cathode material, for use in ASLBs with oxide-based inorganiceorganic-hybrid electrolytes, was investigated by powder X-ray diffraction, field-emission scanning electron microscopy, Brunauere-Emmette-Teller sorption experiments, electrochemical impedance spectroscopy, and galvanostatic testing.
|Jeong-Seon Lee, Kookjin Heo, Ho-Sung Kim, Min-Young Kim, Jaekook Kim, Sung-Won Kang, Jinsub Lim||Master course|
|3-2||4:04:30 PM||Arvind KASBE||Garnet based Ga doped LLZO for highly ionic conductive solid electrolyte for all solid state Li-ion batteries|
A garnet based Ga doped cubic Li7La3Zr2O12 (Ga-LLZO) solid electrolyte prepared by citric acid assisted sol-gel method. The Ga-LLZO pellet shows high conductivity than undoped LLZO after sintred at high temperature. The ionic conductivity is increase due to, (i) Ga doping on Li lattice causes structure modification and increases vacancy site for Li ion, (ii) There is an increase in lattice parameter due to the large size of Ga, (iii) With increased vacancy sites and increased in lattice parameter, diffusion of Li ion in LLZO is enhanced. The high conductive electrolyte help to increase performance of all solid state Li ion batteries.
|Arvind N. Kasbe, Chan-Jin Park||Ph. D. course|
|3-3||4:09:00 PM||Tamal Tahsin KHAN||All solid-state Li-O2 batteries with improved interface|
Recently, all solid-state Li-O2 batteries have attracted significant attention due to the natural abundance of oxygen as an active material for cathode and the theoretical capacity of lithium is 3862 A h kg−1, corresponding to an energy density of ≈11 680 W h kg−1 for a cell voltage of about 3.0 V. The all solid-state Li-O2 battery is also considered an ideal candidate for high-performance energy storage because of its high safety, due to use of non-flammable and non-volatile electrolytes. We are trying to develop all solid-state Li-O2 cell composed of a Li metal as an anode, Ultrathin Atomic Layer Deposition (ALD) of Al2O3 as an interlayer, a perovskite-structured Al-doped Li-La-Ti-O (A-LLTO) as solid electrolyte, and a solid electrolyte integrated cathode frame covered with a carbon layer and CoO nanoparticles as catalysts for the cyclic oxygen evolution reaction and oxygen reduction reaction. In our research, we present a study of ultrathin Al2O3 coatings directly on solid electrolyte surface due to its ability to prevent the direct contact between Li and A-LLTO solid electrolyte to enhance the stability of solid electrolyte against Li anode, and Al2O3 can react with Li to form a thermodynamically stable Li ion conducting LiAlOx solid electrolyte.
|Tamal Tahsin Khan, Chan-Jin Park||Ph. D. course|
|3-4||4:13:30 PM||Hee-Sang KIM||Effects of organic electrolyte additive on the suppression of Li dendrite in Li metal based batteries|
Lithium metal has been considered to be an ideal anode material for rechargeable batteries due to its high theoretical capacity, low density, and the lowest standard red-ox potential. However, Li metal is thermodynamically unstable in organic electrolytes: when Li metal is in contact with an organic electrolyte, it reacts easily with the electrolyte to form a solid electrolyte interphase (SEI) layer. This layer can prevent the direct contact between Li metal and liquid electrolyte and the further decomposition of the electrolyte, once the stable and robust SEI layer forms. Nevertheless, inhomogeneity in chemical composition or thickness of the SEI layer can be the cause of the growth of Li dendrite, leading to short-circuit in batteries. In the present study, we suggest the use of an electrolyte additive to suppress the growth of Li dendrite by forming the uniform SEI layer on Li surface. The Li symmetric cell containing the electrolyte additive was stably cycled over 500 cycles at a current density of 1 mA cm-2, which was >50 times longer than that of the Li symmetric cell without the additive. Further, the Li-O2 cell containing the electrolyte additive was cycled for longer than 200 cycles at a current density of 0.1 mA cm-2 under a limited capacity mode of 1000 mAh g-1, which was >4 times longer than that of the cell without the additive. This electrolyte additive improved the electrochemical performance, especially cyclability of Li-O2 batteries.
|Hee-Sang Kim, Chan-Jin Park||Master course|
|3-5||4:18:00 PM||Pravin DIDWAL||Polymer based solid electrolyte for high temperature Li ion solid state batteries|
An preparation of safety and self standing solid polymer electrolyte is shown to be possible to high temperature all solid state lithium ion batteries. The self standing polymer shows pretty high conductivity, better mechanical properties and good rate performance at high temperature. Considering the above advantages of polymer electrolyte, all solid state lithium ion batteries with polymer electrolyte is applicable even at high temperature.
|Pravin N. Didwal, Rakesh Verma, Chan-Jin Park||Ph. D. course|
|3-6||4:22:30 PM||Bong-Joon SUNG|
Polyurethane based composite solid polymer electrolyte with A-LLTO and succinonitrile for high temperature all solid state Li ion batteries
The polyurethane based composite solid polymer electrolyte with A-LLTO and succinonitrile (CSPE) prepared by simple solution casting method. Here, A-LLTO acts as ceramic filler and succinonitrile acts as a plasticizer. The crystallinity and glass transition temperature of CSPE is observed by XRD and DSC, respectively. The conductivity of the CSPE is calculated by electrochemical impedance spectroscopy. The CSPE shows higher conductivity than conventional PEO based polymer electrolyte at high temperature of 60 oC. The CPSE is capable to show high conductivity because, (i) The addition of A-LLTO/succinonitrile helps to increase amorphous nature of polymer, (ii) There is an increase segmental motion of polymer electrolyte. (iii) Transportation of Li ion is easy due to increased segmental motion of polymer. The high conducting CSPE can apply to the high temperature all solid state Li-ion batteries.
|Bong-Joon Sung, Chan-Jin Park||Master course|
|3-7||4:27:00 PM||Abhishek LOKHANDE||Ag based supercapacitors|
The requisite of cost-effective, efficient and non-toxic routes for nanomaterial synthesis as an effective alternative to expensive and toxic chemical techniques is of prime importance. The present work, for the first time, demonstrates the synthesis of Ag nanoparticles using Kimchi cabbage extract and its further application in an antibacterial and electrochemical supercapacitor. The green synthesized Ag nanoparticles are characterized in detail using comprehensive characterization techniques. The structural, optical, chemical and microstructural properties of the nanoparticles are evaluated using X-ray diffraction (XRD), UV–visible spectrophotometry (UV), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and transmission emission microscopy (TEM) techniques, respectively. The synthesized Ag nanoparticles display effective antibacterial activity against both gram-positive and gram-negative bacteria strains and exhibit a specific capacitance of 423 F/g with an energy density of 14.04 Wh/Kg and power density of 6.41 kW/Kg in supercapacitive studies. The excellent capacitive performance is attributed to the smaller size and porous nature of the Ag thin film which provides fast and efficient ionic transport from the electrolyte to electrode.
|A C Lokhande, Jin Hyeok Kim||Ph. D. course|
|3-8||4:31:30 PM||Nguyen Hung TAI|
Characterization of nonstoichiometric BaBiO3-δ ceramics: Electrical conductivity, phase transitions, and chemical diffusivity
In this work, BaBiO3 was prepared from BaCO3 and Bi2O3 by a solid state reaction method. The sample was pressed into pellets and sintered at 800oC for 24 hours. AC response of BBO bulk sample was measured for a wide range of temperature by using an electrical furnace, a heating stage and a cryostat. Two types of electrodes (gold and silver) result in the systematic differences in electrical behavior, which may be attributed to the different surface catalytic properties. The dielectric and conductive properties indicate the characteristic transitions at the temperatures some of which correspond to the known structural phase transitions, which appear to be closely linked to the oxygen non-stoichiometry. Insitu X-ray diffraction showed the presence of distorted perovskite structure in different atmosphere and temperature. Electrical properties are affected by the atmosphere even at low temperatures near room temperature. Indeed, clear mass relaxations attributable to the oxygen nonstoichiometry were observed in thermal gravimetric analysis even at room temperature. Surprising the kinetics appear to be almost temperature independent up to 400C. Mass relaxations are compared with the relaxations in the AC response. The latter is expected to give more insights into the kinetic mechanism.
|Hung Tai Nguyen, Dang Thanh Nguyen, Thuy Linh Pham, Jong-Sook Lee||Master course|
|3-9||4:36:00 PM||Doan Thanh TRUNG||Controlled-atmosphere sintering of KNbO3|
KNbO3 is a ferroelectric perovskite material and has been studied as a potential lead-free piezoelectric ceramic. Unlike its cousin (K0.5Na0.5)NbO3, the effect of sintering atmosphere on its sintering behavior has not received much attention. In the present work, KNbO3 was sintered in O2, air, N2, H2 and N2-5%H2 and the effect on densification and grain growth behavior studied. Single-phase KNbO3 powder was prepared by the mixedoxide method. Samples were sintered in different atmospheres at 1040°C for 1-10 hours. Sample density was measured by the Archimedes method. Sample microstructure was observed using Scanning Electron Microscopy, SEM-backscatterd. Sample structure was studied using X-ray Diffraction. Samples were single-phase KNbO3 irrespective of sintering atmosphere. Sintering in hydrogen caused a reduction in density, a delay in the onset and a reduction in the amount of abnormal grain growth.
|Doan Thanh Trung, John Gerard Fisher||Master course|
|3-10||4:40:30 PM||Eugenie UWIRAGIYE||Growth of lead-free KNN-based single crystals by solid state crystal growth methods|
Pb(Zr,Ti)O3(PZT) based ceramics are materials with excellent piezoelectric and dielectric performance, but due to their substantial amount of Pb, which is a very toxic material, lead-free piezoelectric ceramics are being studied as their replacements. (K0.5Na0.5)NbO3-based ceramic materials have been found to be one of the most promising candidates to replace PZT. In this work, 0.95(K0.5Na0.5)NbO3-0.05(Bi0.5Na0.5) (Zr0.85Sn0.15)O3 and 0.99(K0.5Na0.5)NbO3-0.01(Bi0.5Na0.5)(Zr0.85Sn0.15)O3 single crystals were grown by solid state crystal growth and the simple low-cost seed-free solid state crystal growth methods. Li2CO3 and Bi2O3 were used in small amounts as sintering aids. Ceramics powders were produced by the solid state reaction method. To verify the single-phase perovskite structure of the powders, XRD analysis was performed. For the SSCG method, <110> KTaO3 seed crystals was buried in the center of the powders and pressed into pellets, then the pellets were sintered at 1150oC for 1h, 3h, 5h,10h and 20h. A single crystal grew onto the seed. The amount of Li2CO3 and Bi2O3 sintering aid addition had a strong effect on the single crystal growth rate. The effect of sintering time was less pronounced. For the SFSSCG method, the pellets were made without seed crystal followed by the sintering process. For both methods, the effect of amount of sintering additions was evaluated. In addition to this, the effect of sintering temperature and time was studied on the second method.
|Eugenie Uwiragiye, John Gerard Fisher||Ph. D. course|
|3-11||4:45:00 PM||Meng MENG|
Growth of 0.96(K0.48Na0.52)(Nb0.95Sb0.05)O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 lead-free piezoelectric single crystals by solid state single crystal growth
Ceramics based on (K0.5Na0.5)NbO3 with a merged rhombohedral-tetragonal phase transition are receiving extensive study as lead-free replacements for Pb(Zr,Ti)O3 piezoceramics [1,2]. It is expected that the piezoelectrical properties can be improved further by using single crystals; however, these materials tend to have complex compositions, making growth of single crystals difficult. In this work, the growth of single crystals of 0.96(K0.48Na0.52)(Nb0.95Sb0.05)O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 using the solid state single crystal growth technique is described. In this technique, ceramic powders are prepared by the mixed oxide method. Seed crystals of KTaO3 are buried in the powders and pressed into pellets. The pellets are sintered and single crystals of the ceramic powder composition grow onto the seed crystals. This technique is suitable for the growth of single crystals of complex composition because it does not involve melting and resolidification of the batch materials.
The microstructure of the grown single crystals and surrounding matrix grains is examined using scanning electron microscopy. Chemical composition is examined using energy dispersive spectroscopy. The structure and phase transitions of the single crystals is studied using microRaman scattering. The dielectric and ferroelectric properties are also measured.
|M. Meng, T. L. Pham, J. S. Lee and J. G. Fisher||Master course|
|4-1||5:00:00 PM||Byeonghoon LEE||Investigations on the CuZnSn(S,Se) absorb layer during sulfo-selenization|
In this work, earth-abundant CZTSSe thin film solar cells were fabricated by sulfo-selenization of the Mo/Zn/Sn/Cu metallic precursors. The CZTSSe qualities are vital aspects and factors that would greatly decide the photovoltaic performance of CZTSSe solar cells. However, due to inhomogeneous CZTSSe grain growth during selenization, void defects and secondary phases would emerge at the CZTSSe/Mo interfaces. The influences of forming absorption layer were investigated by tuning temperature during sulfo-selenization process and the crystal structure and phase of sulfo-selenized absorbers were analyzed by X-ray diffraction(XRD). The phases were also confirmed by a Raman spectrometer. The surface and cross-sectional morphologies of films were observed using a Scanning electron microscope(SEM). Lastly, the chemical compositions were measured by X-ray fluorescence spectroscopy (XRF). Through these results, we discuss how to be formed CZTSSe grain growth and to prevent growing defects and secondary phases during sulfo-selenization process. At the end, the schematic of CZTSSe forming process was presented in accordance with changing of temperature from 100℃ to 600℃.
|Byeonghoon Lee, Jinhyeok Kim||Master course|
|4-2||5:04:30 PM||Jun Sung JANG||Influence of working pressure on the properties of In-doped SnO2 (ITO) thin films for Cu2ZnSn(S, Se)4 thin film solar cells|
Cu2ZnSn(S,Se)4(CZTSSe) has been emerged as an attractive candidate to replace CdTe, CIGS, silicon based thin film solar cells (TFSCs). In a present study, In doped SnO2 (ITO) thin films as a window layer in CZTSSe TFSCs were optimized to improve a device efficiency. ITO thin films are deposited on soda lime glass (SLG) substrate by radio frequency (RF) magnetron sputtering by varying the working pressure during the deposition. The influence of different working pressure on the morphological, optical and electrical properties of ITO thin films as well as on the CZTSSe TFSCs efficiency were investigated. All the deposited thin films showed a uniform microstructure with transmittance of over 83% in visible region though it possesses comparable band gap and resistivity differences. Especially, ITO thin film deposited at 1mTorr showed improved electrical properties having lowest resistivity of 4.59 x 10-4 Ωcm, higher carrier concentration of 3.94 x 1020 cm-3, high mobility of 34.3 cm2v-1s-1 and lower sheet resistance of 15.2 Ω/SQ respectively.
|Jun Sung Jang, Jin Hyeok Kim||Ph. D. course|
|4-3||5:09:00 PM||In Jae LEE||Effect of annealing pressure on Cu2SnS3(CTS) thin film solar cells|
Cu2SnS3(CTS) is one of the interesting absorber compound owing to the presence of earth-abundant and nontoxic elements. In the present work, Cu2SnS3(CTS) thin film solar cells have been fabricated using sputtered deposited Cu/Sn metallic precursors on Mo-coated soda lime glass(Mo-SLG) substrate. The metallic precursor thin films are sulfurized in a graphite box containing S powder using rapid thermal annealing (RTA) furnace. The influence of varied sulfurization parameter (pressure 300~500torr) on the CTS thin film properties and its solar cell performance are studied. The morphological, structural and electrical properties of the CTS absorber layer are studied using field-emission transmission electron microscopy (FE-TEM), Fluorescence Spectrometer (XRF), X-ray diffraction (XRD) and J-V. The best power conversion efficiency of 2.80 % with a short circuit current density of 28.1 mA/cm2, an open circuit voltage of 207.5mV, and fill factor of 48% is obtained.
|In Jae Lee, Jin Hyeok Kim||Master course|
|4-4||5:13:30 PM||Eunae JO||8% flexible CZTSSe solar cell on Mo foils|
A typical advantage of the thin film solar cell (TFSC) is that it is a low manufacturing cost due to use of a small amount of raw material. Currently, kesterite-based TFSCs have been studied mainly on the glass substrate. However, when thinner and lighter flexible substrates are used instead of conventional glass substrates, it is more advantageous in the roll-to-roll process application, thereby achieving higher productivity and reducing manufacturing cost. Metal foils have several distinct advantages over polyimide as well as heat resistance. And Mo foil is suitable considering to heat expansion coefficient. In addition, high purity Mo foils do not require a barrier layer in the cell structure, while other substrates such as stainless steel contain deep levels of impurities such as Fe, which adversely affect the electronic properties of the absorber. In this work, we have reported an approach to manufacturing Cu2ZnSn(S,Se)4 (CZTSSe) films on commercial Mo foils by sputtering deposition. The sputtering method is an advantageous method for large area production in the future. Among the worldwide groups using flexible substrates, alkali elements doping was applied to groups that gained more than 6% efficiency, but we proceeded without doping with alkali elements. After the CZTSSe device was completed with Mo foil/CZTSSe/CdS/ZnO/Al:ZnO/Al structure, efficiency of 7.995% was achieved at 0.27 cm2 of device area.
|Eunae Jo, Jin Hyeok Kim||Ph. D. course|
|4-5||5:18:00 PM||Myeng Gil GANG||Fabrication and characterization of Cu2ZnSn(SxSe1-x)4 (CZTSSe) thin film solar cells based on sputtering process|
Cu2ZnSn(S,Se)4 thin film solar cells have been fabricated using sputtered Cu/Sn/Zn metallic precursors on Mo-coated soda lime glass substrates without using a toxic H2Se and H2S atmosphere. The as-deposited metallic precursors were sulfo-selenized in a graphite box containing S and Se powder using a rapid thermal annealing (RTA) furnace. Thin film solar cells were fabricated after sulfo-selenization process using 25 nm CdS buffer layer, a 100 nm intrinsic ZnO, a 600 nm of Al-doped ZnO, with Al/Ni as a top metal contact. The Effect of absorber composition ratio, annealing process condition and CdS buffer layer thickness on the morphological, structural and electrical properties have been studied using field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, I-V and quantum efficiency measurement system, and time-resolved photoluminescence spectroscopy, respectively. The fabricated Cu2ZnSn(S,Se)4 thin film solar cell shows the best conversion efficiency of 11.80% (Voc : 484.6mV, Jsc : 37.50mA/cm2, FF : 64.91%, and active area: 0.3 cm2).
|Myeng Gil Gang, Jin Hyeok Kim||Post-doctoral researcher|
|4-6||5:22:30 PM||Vijay KARADE||Impact of Sn content and compositional ratio on the power coversion efficiency|
In the present wok, earth-abundant element based CZTSSe thin film solar cell device were fabricated using vacuum deposition method. The metallic Cu, Zn and Sn precursors were deposited sequentially by sputtering method on the Molybdenum coted soda lime glass as Mo/Zn/Sn/Cu respectively. The deposition time of Sn precursor were varied and the effect of Sn content on compositional ratio along with power conversion efficiency were analyzed. The phase purity and corresponding crystal structure of sulfo-selenized absorbers were examined using X-ray diffraction(XRD) and the cross-sectional morphologies of prepared thin films were observed using a Scanning electron microscope(SEM). To conclude, the elemental compositional ratio were measured by X-ray fluorescence spectroscopy (XRF). Based on this study, it was observed that the increasing Sn content suppressed the voids formation but formation secondary phases significantly reduced the device efficiency. The device with optimal deposition time and compositional ratio have 11.03 power conversion efficiency with Voc of 0.49 mV, Jsc- 34.83 mA/cm2 and FF-64 %.
|Vijay Karade, Jin Hyeok Kim||Ph. D. course|
|4-7||5:27:00 PM||Dongmin LEE|
Influence of Zn ratio on the properties of Cu2ZnSn(SxSe1-x)4 (CZTSSe) thin film solar cells by high pressure annealing process
Cu2ZnSn(S,Se)4 is a good material substituted for Si as a absorber layer of solar cell. It has proper absorption coefficients, band gap energy and most of all it is abundant material and Non-toxic elements. Cu, Zn, Sn thin film metallic precursor were prepared by sputtering on Mo/glass . The precursor thin films were annealed as a absorber layer using Rapid Thermal Annealing(RTA) system in a graphite box with S and Se powder. And deposits Cadnium Sulfide (CdS) as a buffer layer by Chemical Bath Deposition(CBD) method. i-ZnO and Al-doped ZnO window layers were deposited using the Rf-sputter and the aluminum electrode was formed by a DC sputtering process. We studies how to optimize the composition ratio in High pressure RTA system.
|Dongmin Lee, Jin Hyeok Kim||Undergraduate RA|
|4-8||5:31:30 PM||Hiji JEONG||Formation of Zn(O,S) buffer layers by atomic layer deposition for Cu2ZnSn(S,Se)4 thin film solar cells|
To fabricate high performance thin film solar cells (TFSCs), CdS is widely used as an n-type buffer layer for various types of absorbers. CdS has a band gap of 2.4 eV that leads to a loss in the blue region of the solar spectrum, which could be potentially recovered by a more transparent layer. However, due to the toxicity of Cd, alternative buffer layer materials are needed. Zn(O,S) is a promising alternative buffer layer to CdS in Cu2ZnSn(S,Se)4 (CZTSSe) based solar cell due to its large bandgap and nontoxic elements. On the other hand, atomic layer deposition (ALD) technique is a great tool for the conformal deposition of a thin film with a precise thickness and desired stoichiometry.
In this study, we controlled the Zn(O,S)-ALD conditions such as growth temperature and O/(O+S) ratio. The highest efficiency of 8.99% (Voc = 458 mV, Jsc = 36.85 mA/cm2, and FF = 53.2%) was obtained at a growth temperature of 90 ºC with an O/(O+S) ratio of 0.67. The efficiency of the standard CdS-based cell was 9.26% (Voc = 467 mV, Jsc = 36.96 mA/cm2, and FF = 53.7%). Our cell efficiency is the highest efficiency ever reported so far among Zn(O,S)-buffer-based CZTSSe TFSCs to our best knowledge. More detailed analyses focusing on the materials properties as well as device performance will be discussed.
|Hiji Jeong, Jaeyeong Heo||Master course|
|4-9||5:36:00 PM||Dajeong LEE||Improved efficiency of Sb2Se3/CdS thin film solar cells : The effect of pre-annealing of absorbers|
Sb2Se3 is one of the alternative absorber materials for thin-film solar cells (TFSCs) comprising non-toxic and low-cost elements. It has an appropriate bandgap of 1.0 - 1.2 eV and high absorption coefficient (> 105cm-1). But till date, the efficiencies obtained from the Sb2Se3-based solar cells are relatively low compared to its theoretical limit of ~ 25%. In order to improve the efficiency, one of the requirements is to improve the crystallinity of Sb2Se3 absorber layer. In our study, the effect of pre-annealing duration at 100 °C prior to rapid thermal annealing (RTA) have been studied. The duration of pre-annealing influences the final morphology, crystallinity, and preferred orientation of thermally evaporated Sb2Se3. We confirmed that the morphology of the Sb2Se3 thin film changed as the duration of pre-annealing increases from 0 min to 100 min. Also, We fabricated the cells with a change in the duration of pre-annealing of absorber layer and compared the performance of the solar cells. Further detailed analyses using X-ray diffraction, Raman spectroscopy and cell parameters will be dealt in our presentation.
|Dajeong Lee, Jaeyeong Heo||Master course|
|4-10||5:40:30 PM||Jae Yu CHO||Growth of SnS thin Films by vapor transport deposition for thin-film solar cell application|
The broad use of photovoltaic energy as an infinite source of clean energy is still limited because of the high cost of power generation. Tin monosulfide (SnS) has been researched widely as a good candidate for earth-abundant photovoltaic absorber. SnS has a direct band with the bandgap of 1.2~1.5 eV and high optical absorption coefficient over 104 cm-1, which is nearly optimum for photovoltaic solar energy conversion. Even though SnS has many advantages, it is difficult to grow pure-phase SnS because of easy formation of secondary phases such as SnS2 and Sn2S3. In this work, SnS films were deposited by vapor transport deposition using SnS powder in a horizontal furnace. We changed pressure and temperature of SnS powders and substrates. We tried to find the optimal condition to obtain phase-pure SnS thin films. It was found that the substrate temperature and pressure influence the final phase of the deposited sulfides. Device structure of fabricated cells is glass/Mo/SnS/CdS/ZnO/AZO/Ni/Ag. More details on structural, optical, and electrical properties will be discussed in this presentation.
|Jae Yu Cho, Jaeyeong Heo||Ph. D. course|
|4-11||5:45:00 PM||Pravin PAWAR|
Deposition of Zn1-xCdxS Buffer Layer Using Successive Ionic Layer Adsorption and Reaction (SILAR) Method for SnS Solar Cell
Successive ionic layer adsorption and reaction (SILAR) deposited Zn1-xCdxS buffer layer have shown great improvement in efficiency and overall performance for CZTS and CIGS thin film solar cells. In this work, we have implemented SILAR deposited Zn1-xCdxS buffer layer for SnS thin film based solar cell. Here, SnS absorber layer was deposited on Mo-coated soda lime glass by using vapor transport deposition (VTD) method. To deposit Zn1-xCdxS buffer layer Zinc acetate, Cadmium acetate and Sodium sulfide were used as a source of Zn+2, Cd+2 and S-2 ions respectively. It is observed that the efficiency of SnS/Zn1-XCdXS based solar cell was increased with increase in Cd+2 concentration in the Zn1-xCdxS buffer layer. The thickness of Zn1-xCdxS buffer layer was measured by using SEM cross-section image. 30 SILAR cycles were performed at room temperature to deposit ~60 nm thick buffer layer. The highest Voc value was obtained for SnS/Zn0.2Cd0.8S and SnS/Zn0.4Cd0.6S cells comparing to the SnS/CBD-CdS reference cell.
|Pravin Pawar, Jaeyeong Heo||Ph. D. course|
Neerugatti Krishna Rao ESWAR
|Trapping of thermodynamically meta-stable π-SnS during vapor transport deposition for energy applications|
Often optical devices seek nanocrystals with a lack of center of symmetry such that their properties can be varied as a function of direction/orientation. Considering this advantage, we are developing π-SnS which is a recently much focused highly meta stable compound from tin sulfides group with cubic structure. Theoretical studies and very few experiments show that π-SnS possess a Eg of 1.7 eV with forbidden transitions unlike orthorhombic SnS having a direct Eg between 1.2 – 1.5 eV. Stabilizing the phase of tin sulfide with cubic structure is an uphill task where wet chemical methods do not offer freedom to tune the thermodynamics of the material for thin film deposition. Hence, we are approaching π-SnS with vapor transport deposition such that optimizing pressure, temperature may trap and stabilize the growth of SnS at cubic phase for solar cell applications. Further, orientation of growing SnS can be tweaked to retrieve interesting properties. Having only rotation or screw symmetry allows π-SnS to show non-linear optical properties that may expand the scope of this material beyond solar cell applications. This work emphasizes on growing π-SnS thin films on different substrates by optimizing the growth and fabricating solar cells with choices of seed and buffer layers. Also, this investigation may shed light on some interesting characteristics of cubic SnS that could be a fundamental study for future works on this material.
|N K R Eswar and Jaeyeong Heo||Post-doctoral researcher|
|5-1||7:00:00 PM||Hyo Seok LEE||Study on the removal of silver, copper and copper oxide using supercritical CO2|
Since solar modules have a life span of about 20 years, a large amount of waste modules will be discharged in the future and how to handle them is a problem. Most of the metal in the solar module is dependent on imports. Especially, if imported metals and silicon recovery technologies are developed from solar cells, which are in increasing demand, import substitution is expected, which is essential technology for strengthening competitiveness in renewable energy sector. In this study, supercritical CO2 was used for the recovery of valuable metals and silicon. Supercritical fluid is defined when the temperature and pressure above the critical point are applied, the characteristics of gas and liquid are mixed. Its density or solubility of a supercritical fluid is close to that of a liquid, and its viscosity, diffusivity and thermal conductivity are similar to those of a gas. CO2 has various advantages as a supercritical fluid solvent such as low critical point, high density, eco-friendly, harmless, and non-inflammable. In this work, an experiment was conducted to remove silver, aluminum, and copper thin films deposited on a silicon substrate with a change in the temperature, pressure, and flow rate using supercritical CO2. Finally we compared the efficiency of the removal, and studied the influence of temperature, pressure, and flow rate on metal removal.
|Hyo Seok Lee, Jae Yu Cho, Jaeyeong Heo||Master course|
|5-2||7:04:30 PM||Yong Tae KIM||Fabrication of AlOx/TiOx bilayer anti-reflective structures for silicon optical coupling lens|
We investigated the possibility of using an AlOx/TiOx bilayer as AR structures for Si, focusing on the wavelengths of 1270–1330 nm. The thicknesses of each layer were optimized by simulations using the Essential Macleod software. For experimental demonstration, atomic layer deposition (ALD) was used for the growth of AlOx and TiOx. The AR structure lowered the reflectance, close to 0%, at the wavelength band of 1270–1330 nm, which enabled an increase of the transmittance by approximately 40%, compared with bare Si. Despite the low reflectance close to 0%, transmittance of ~88%, which is slightly lower than expected, was obtained. An additional air annealing at 300 °C for 2 h led to a crystallization of the amorphous TiOx into anatase phase, which yielded an improved transmittance of ~99%.
|Yong Tae Kim, Jaeyeong Heo||Master course|
|5-3||7:09:00 PM||Vijay PATIL||Morphological, structural, optical and electrical properties of the beta gallium oxide thin films|
There has been surge in the research study of Ga2O3 thin films owing to its potential use in power electronics, phtoresistors, photodiodes and gas sensors. Ga2O3 is an ultra wide band gap material ( 5 eV ) which is the prime reason for investigating the suitability for the range of applications from high temperature electronics, phosphorous luminescence to solar cells. The research of Ga2O3 thin films and subsequent application is in initial stage. The prime reason is the lack of in depth analysis of optical, structural and electrical properties of material. The detailed investigation of the properties of materials requires the high quality thin films. Therefore, this importance of high quality thin film development requires the thorough examination of the growth factors on the formation of thin films. In the present work, we have investigated the effect of variable growth factors on the optical and structural properties of the beta phase Ga2O3 thin films. The growth factor variables provides insight about the appropriate and suitable growth variables for desired thin film according to application. The growth factors such as temperature, RF power, gas pressure ambient gas ratio will be studied for their effect on beta phase gallium oxide thin film. Also, the effect of doping will be investigated for the study of electrical properties of the material.
|Vijay Patil, Byung-Teak Lee||Ph. D. course|
|5-4||7:13:30 PM||Chandra KUMAR||340nm UV-emission on a full 2-inch AlGaN/GaN wafer by cathodoluminescence|
A demonstration of UV-emission at ~340nm over a full 2-inch AlGaN/GaN wafer on sapphire achieved by electron-beam source and this emission is termed as cathodoluminescence (CL). By optimizing AlGaN/GaN quantum well, led us to choose 20-multi quantum wells (MQWs) as the optimum number with a maximum efficiency for this design combination. The CL spectra was recorded, at a beam energy of 7keV with duty of 1% and a repetition frequency of 1kHz. The MQW emission peaks at Wavelength =340nm with a FWHM of about 20nm was determined by the Gaussian fit. To understand further about the UV-absorption, Monte-Carlo simulations by CASINO were performed at different incident e-beam energies EB and the best Pout was obtained at EB =7keV. The results from Monte Carlo simulations (CASINO) correlate between the experimental and simulation data.
|C. M. Manoj Kumar, Wael Z. Tawfik and June Key Lee||Ph. D. course|
|5-5||7:18:00 PM||Wael Zakaria TAWFIK|
Facile synthesis of sputtered p-Cu2O/ZnO photocatalyst on a metallic titanium substrate to boost the performance of photoelectrochemical water splitting
Earth-abundant Cu2O-based photocatalysts are promising light absorbing materials for highly efficient solar hydrogen production through a photoelectrochemical (PEC) water splitting system. However, growth of these structures over incompatible and low conductive substrates hinders the interfacial charge transport kinetics of photo-generated carriers, which severely reduces PEC performance. Herein, we report a Cu2O photocathode directly grown on a metallic Ti coated on Mo-glass substrate with a ZnO protective nanolayer, to reduce the interfacial transport resistance of photo-generated charge carriers (holes) at the electrode–substrate interface, as well as to improve the separation and extraction efficiency at the electrode–electolyte interface, compared to that grown on a conventional FTO substrate.
|Wael Z. Tawfik, June Key Lee||Post-doctoral researcher|
|5-6||7:22:30 PM||Thi Lan TRAN|
Impedance modeling of deep Levels in ZnO: Applications to ZnO bicrystalline intefaces and ZnO single crystalline photoanodes
AC response of deep levels in ZnO can be modeled as the series connection of the Gerischer impedance and the ideal capacitor, which can be compared to ideal resistor element in the Debye model. The modeling was applied to admittance spectroscopy for the Schottky depletion layers at ZnO bicrystalline interfaces and ZnO/electrolyte interface of ZnO photoanodes in photoelectrochemical cells (PEC). The parallel connection of the capacitance functions with different relaxation times can describe properly the admittance response of ZnO bicrystalline interfaces. For the PEC impedance Bisquert transmission line model with interfacial Warburg impedance, which was recently suggested as generic electrochemical impedance model, was connected in parallel to the Schottky capacitance represented by Gerischer model.
|Thi Lan Tran, Hung Tai Nguyen, Dang Thanh Nguyen, Eui-Chol Shin, J. Maier, Jong-Sook Lee||Master course|
|Cancelled||5-7||7:27:00 PM||Mahesh SURYAWANSHI|
A facile, one-step electroless deposition of NiFeOOH nanosheets onto photoanodes for highly durable and efficient solar water oxidation
A low-cost, highly efficient and durable photoelectrochemical (PEC) water-splitting system can be realized through designing a hierarchical core/shell nanostructured photoanode entirely composed of Earth-abundant elements. Herein, we report the rational design of a core/shell nanostructured photoanode with a TiO2 nanorod (NR) array as the core and a highly active Earth-abundant NiFe oxyhydroxide ((Ni1−xFex)OOH, NiFeOOH) oxygen evolution catalyst (OEC) as the shell for PEC water oxidation. Specifically, the NiFeOOH nanosheets were prepared via a facile, one-step electroless deposition method for a short reaction time of 10 min at room temperature. The TiO2/NiFeOOH core/shell nanostructured photoanode exhibits an unprecedented enhancement in photocurrent density (3.85 mA cm−2 at 1.23 V vs. a reversible hydrogen electrode, (RHE)), no decay in photocurrent density over 24 h, and an obvious cathodic onset potential shift of 133 mV compared to the TiO2 NRs (0.73 mA cm−2 at 1.23 V vs. RHE). The electron transfer mechanism is discussed through electrochemical impedance spectroscopy studies and calculated band alignments via ultraviolet photoelectron spectroscopy characterization. This work not only suggests a simple, room temperature electroless strategy for integrating Earth-abundant catalysts with photoanodes, but also accelerates the development of rationally designed core/shell photoanodes for efficient and durable solar water oxidation.
|Mahesh P. Suryawanshi, Jin Hyeok Kim||Post-doctoral researcher|
|5-8||7:31:30 PM||Umesh SURYAWANSHI||Spinel structured NiCo2O4 nanowire arrays supported on Ni-foam as an efficient electrocatalyst for water splitting|
Developing efficient and earth-abundant electrocatalyst for water splitting is of great importance with increasing clean energy demand. Herein, we report the development of a 3D hierarchical spinal structured NiCo2O4 nanowire arrays decorated on nickel foam as scaffold support, enabling superior catalytic activity towards water-splitting reaction in alkaline media. This 3D hierarchical structure is binder-free which enhances the charge transfer and strong chemical coupling at the interface. Serving as an electrode catalyst, the fabricated hierarchical structure catalyzes the HER with an overpotential of 264 mV to deliver the current density of 10 mA cm-2, indicating the utilization of the material as an efficient electrocatalyst towards water splitting.
|Umesh P. Suryawanshi, Jin Hyeok Kim||Integrated course|
|5-9||7:36:00 PM||Yelyn SIM||Graphene-derived low-dimensional catalysts for efficient (photo)electrochemical hydrogen production|
In the light of the current progress in renewable energy technologies, Hydrogen energy is one such promising strategy which is showing promising outcomes. Much of the research is devoted in focusing on hydrogen production through electrocatalytic reduction of water to molecular hydrogen through hydrogen evolution reaction (HER) which can provide the much sustainable energy supply needed for the future, but in terms of its commercial application is hampered by the use of noble precious metal catalysts. As there is an inadequate source of noble metal catalysts in order to gain a sustainable hydrogen production is rather important to find cost-effective alternatives to these precious catalysts with higher electrocatalytic activities and better stabilities. Despite the tremendous efforts put into developing non-noble catalysts, the main focus in largely lies in the direction of transition metals and their derivatives. Carbon-based materials and their derivatives have shown some promising insights owing to their tunable molecular structure, abundance and more importantly their strong tolerance towards acid/alkaline environments. Recent advances in low-dimensional carbon-based materials in metal-free catalysts have shown promising potential for the future in renewable energy-related electrocatalytic water splitting.
|Yelyn Sim, Uk Sim||Master course|
|5-10||7:40:30 PM||Tae-Yong AN|
Polydopamine-mediated carbon-Rich molybdenum carbide-phosphate nanohybrids as a progressive electrocatalyst for enhanced hydrogen evolution reaction
The development of dynamic electrocatalysts for hydrogen evolution reaction (HER) is essential for the large-scale progression of effective and low-cost electrochemical hydrogen production. Herein, we synthesized facile carbon-rich Mo2C-MoP nanohybrids via polydopamine-mediated thermal reduction and carbonization process as an effective HER electrocatalyst. The formation of mixed-phase nano-globular carbon-rich Mo2C-MoP nanohybrids was extensively analyzed. All the prepared Mo2C-MoP nanohybrid electrocatalysts were tested for HER electrocatalytic activity, and showed enhanced HER activity by demanding low overpotential of 147 mV to attain high current density of 20 mA cm-2, yielding a low Tafel value of 64.92 mV dec-1 in strongly alkaline KOH electrolyte. Therefore, these nature abundant and easy-to-synthesize Mo2C-MoP nanohybrid electrocatalysts with dynamic performance will have significant impact on electrocatalytic hydrogen evolution reactions.
|Tae-Yong An, Subramani Surendran, Jung Kyu Kim and Uk Sim||Integrated course|
|5-11||7:45:00 PM||Pravin BABAR||Cobalt iron hydroxide as a precious metal‐free bifunctional electrocatalyst for efficient overall water splitting|
Highly efficient and stable electrocatalysts from inexpensive and earth‐abundant elements are emerging materials in the overall water splitting process. Herein, cobalt iron hydroxide nanosheets are directly deposited on nickel foam by a simple and rapid electrodeposition method. The cobalt iron hydroxide (CoFe/NF) nanosheets not only allow good exposure of the highly active surface area but also facilitate the mass and charge transport capability. As an anode, the CoFe/NF electrocatalyst displays excellent oxygen evolution reaction catalytic activity with an overpotential of 220 mV at a current density of 10 mA cm−2. As a cathode, it exhibits good performance in the hydrogen evolution reaction with an overpotential of 110 mV, reaching a current density of 10 mA cm−2. When CoFe/NF electrodes are used as the anode and the cathode for water splitting, a low cell voltage of 1.64 V at 10 mA cm−2 and excellent stability for 50 h are observed. The present work demonstrates a possible pathway to develop a highly active and durable substitute for noble metal electrocatalysts for overall water splitting.
|Pravin Babar, Jin Hyeok Kim||Ph. D. course|
|6-1||8:00:00 PM||Dong-Kyu LEE||Nitrogen photoreduction|
Ammonia production has been paid attention to provide fertilizer for agriculture. Besides, ammonia is also considered as an essential source of energy in terms of internal combustion engine and hydrogen for fuel cell systems. Until now, Haber-Bosch process is exclusively used world-wide for the large-scale production of ammonia. But, this process needs lots of energy source and sophisticated instruments necessitating conditions of 150 atmospheric pressure and 500C to break the triple bond for converting nitrogen to ammonia. Further, it consumes 1-2% of current global energy production and relies on fossil fuels as an energy source, which paves way for emission of CO2 gas causing environment pollution. Owing to the above concerns, we aim to reduce the consumption of energy source to nitrogen reduction. This major issue can be resolved by the prospect of developing electrochemical process as an efficient tool to produce high pure ammonia. In this study, we have specifically researched the photocatalytic nitrogen reduction of transition metals at ambient conditions. The photocatalyst is well thought-out to be one of the efficient electrochemical catalysts that uses the solar energy to promote the catalytic activity. These photocatalysts have already proved its superiority in the hydrogen reduction reaction, and it has been found that they are also effectively suitable in term of nitrogen reduction reaction. However, there are still a lot of parts that are still being studied.
|Dong-Kyu Lee, Jude John, Tae-Yong Ahn, Suren, Uk Sim||Undergraduate RA|
|6-2||8:04:30 PM||Yoon Gu LIM||Electrochemical reduction of CO2 to CO with transition metal and nitrogen co-doped porous carbon electrocatalyst|
The phenomenal existence of destructive carbon dioxide (CO2) in the atmosphere is considered as a global challenge. Reducing these excess CO2 in a constructive way has been a great issue for the environment. The electrochemical reduction of CO2 to hydrocarbons or carbon monoxide is an assuring technique to this concern. However, reduction of CO2 in aqueous electrolyte has been a challenge due to more positive reduction potential with protons, such as hydrogen evolution reaction. Therefore, the reduction of carbon dioxide requires higher overpotential compared to other competing reactions. Here, three-dimension porous transition metal and nitrogen co-doped carbon catalysts are prepared for the selective production of carbon monoxide from CO2. Nitrogen doped carbon catalysts are well known for their performance in oxygen reduction reaction, but they also have been investigated broadly for the activity of nitrogen sites for CO2 reduction reaction. In addition to nitrogen sites, transition metal atoms are co-doped into carbon structure as additional active sites to improve their efficiency. Yet the low solubility of CO2 in aqueous electrolyte limits the current density for the process. Therefore, electrolysis cell with a membrane electrode assembly is introduced to further increase the productivity by enhancing CO2 mass transport efficiency.
|Yoon Gu Lim, Do Hun Kim, Yelyn Sim, Uk Sim||Undergraduate RA|
|6-3||8:09:00 PM||Lakshya MATHUR||Phosphate-based intermediate temperature proton conducting fuel cell (ITFC)|
Sustainable growth of renewable energy resources required the formation of an appropriate material which can fulfill the final goal of the application area. In this view, fuel cell is one of the potential candidate that can fulfill different energy requirements without any harmful byproduct. The fuel cell can be broadly classified into two categories of application i.e. Stationary and mobile. For stationary applications such as in industries, they need a high temperature (800-100℃) operating fuel cells such as solid oxide fuel cells (SOFC). However, for mobile applications low temperature (<100℃) or intermediate temperature (150-600℃) operating fuel cells are suitable. Polymer-based fuel cells (PEMFC) are related to low-temperature fuel cells whereas, phosphate-based proton conducting fuel cells (PCFC) are associated with intermediate temperature fuel cells. Polymer-based fuel cells are also proton conducting in nature but they have temperature limitation up to 100℃. Ammonium polyphosphate, Pyrophosphate and solid acid electrolyte based fuel cells are commonly used for phosphate-based ITFC’s. Tetravalent metal Pyrophosphate’s based ITFC’s have significant proton conductivity in desired temperature range i.e. >10-2 S Cm-1 at 150-300℃. While working on pyrophosphate based ITFC’s we are trying to find issues related to their performance & stability and solutions for the same.
|Lakshya Mathur, Sun-Ju Song||Ph. D. course|
|6-4||8:13:30 PM||Aniket KUMAR||Novel multifunctional polymer electrolyte membrane for fuel cell application|
Till now, non-renewable fuels such as natural gas, oil and coal are extensively used energy sources. But due to their limited reserve it is predicted that in future its shortage leads to power failure, mainly in developing countries where demand is very high. In this fast devolving world, a clean alternative fuels with zero emission fuels are in demand. So, polymer electrolyte membrane fuel cell is one of the promising alternative renewable energy system which can fulfill the future energy demand and overcome power shortage. But, such system have major issues such as rapid degradation of electrolyte membrane and low proton conduction which decreases the overall polymer electrolyte fuel cell (PEFC) performance and durability. Due to this, PEMFCs are not in widespread commercial use and considerable research have been focused. Keeping this in mind, my research area is focussed on the development of multifunction polymer electrolyte membrane that can deal with the problem of chemical degradation and low proton conductivity. Such hybrid membrane will help to improve the overall efficiency and durability of polymer based fuel cells,
|Aniket Kumar and Sun-Ju Song||Post-doctoral researcher|
|Cancelled||6-5||8:18:00 PM||Aman BHARDWAJ||Mixed-potential NOx sensors|
The air pollution caused by the continued emission of toxic gases from automobile and industrial exhausts are well known for their severe adverse effects on nature and living organism. Among various gaseous pollutants, Nitrogen oxides (NOx) are the most hazardous and prominent air pollutant produced by means of an endothermic reaction among nitrogen and oxygen at high temperatures, mostly in the combustion processes. It results in a number of environmental and health issues like photochemical smog and acid rain along with several respiratory and cardiovascular diseases etc. Due to the rising concern about its high toxicity and environmental impact, researchers around the globe are contributing towards the development of reliable and highly stable sensing techniques for their real-time quantification and further improvement in the efficiency of the combustion processes. Among the various gas sensing techniques for NOx detection, the solid-state electrochemical sensors working on the mixed-potential sensing mechanism are considered most versatile and reliable due to their high stability under harsh environments. While studying the Mixed-Potential NOx sensors, our major emphasis is upon identifying the key issues limiting the sensor performance and developing possible solutions for the same.
|Aman Bhardwaj, Lakshya Mathur, In-ho Kim, Aniket Kumar, Sun-Ju Song||Ph. D. course|
|6-6||8:22:30 PM||Thuy Linh PHAM||Oxygen transport in GDC:LSCF composites for oxygen transport membranes application|
Ceramic membranes with high oxygen permeability have recently received increased attention since they can be a promising candidate to supply pure oxygen to oxy-fuel plants for CO2 capture. Dual-phase membranes of the percolating mixed-conducting oxides LSCF (La0.6Sr0.4Co0.2Fe0.8O3-δ) as an electronic conductor in GDC (Ce0.9Gd0.1O2-δ) as an oxygen ion conductor matrix are under active development. Electrical conductivity relaxations have been used for the determination of chemical diffusivity and surface reactivity which determines the kinetics for the high performance oxygen transport membranes. Unlike conventional bar-shape samples for 4-probe conductivity, van der Pauw method applied to the disk samples in this work allows the systematic investigation on the effects of catalytic surface layers such as La1-xSrxCoO3-δ. Conductivity relaxations were monitored upon change in the atmosphere between air and nitrogen. Chemical diffusion phenomena in the dual-phase composites are not yet clearly understood. Instead of applying the solutions of the diffusion equation for the single phase which have issues, it is suggested to examine the Laplace-Fourier transform of the relaxation in the time domain to the frequency domain. Modification of the diffusion equations represented by the transmission-line models can be much easily and comprehensively performed.
|Thuy Linh Pham, Ji Haeng Yu, Jong-Sook Lee||Integrated course|
|6-7||8:27:00 PM||Jong Hyeok BAK||Strength-toughness trade-off high-entropy titanium alloy development for biomedical application|
This presentation is about the development of titanium alloy for strength toughness control and entropy biomaterials. Currently, High Entropu Alloys research has been in continuous research since 2004 and most of them are in the introduction period to remain in the basic research, but it is likely to be used in various fields. It is also important to develop new alloys that complement the disadvantages of existing biomedical stent alloys have. In the use of metal stents for blood vessels, titanium must have strength and ductility that are opposite properties. The final target properties of the alloys are aimed at the development of alloys with a tensile strength (T.S.) ≧ 1 GPa, an elongation ≧ 40% and a pitting corrosion potential ≧ 1.0 Vssc. Current alloys develop non-equiatomic alloys by increasing the Ti content starting from the equiatiomic HEA of Ti, Cr, V, Mo and Zr. Alloys were prepared by vacuum arc melting and centrifugal casting, and the properties of alloys were evaluated by phase stability and mechanical properties tests through microstructure observation of alloys. Furthermore, the optimum process of calcination / heat treatment based on processing heat treatment is derived through dual phase and toughness enhancement mechanism, TRIP and TWIP effect in HEA.
|Jong Hyeok Bak, Kwangmin Lee||Undergraduate RA|
|6-8||8:31:30 PM||Sharif HAMZA||Nitriding of titanium surface by atmospheric plasma technique|
The aim of this study is to check whether titanium-nitride properties are improving with different parameters using atmospheric plasma technique. Recent research shows titanium nitride is widely using in different fields including medical implants. We are trying to produce titanium nitride thin layer on titanium surface at laboratory environment by using atmospheric plasma technique. The resultant treated sample than observed with X-Rays Photo electron spectroscopy (XPS). XPS analysis is used for further investigation of material identification (characterization). Later on we also have plan to check the required titanium nitride surface interactions with living cells.
|Sharif Hamza, Hoonsung Cho||Integrated course|
|6-9||8:36:00 PM||Alam KHURSHED||Synthesis of graphene oxide by atmospheric plasma and its effect on osteoblast bone regeneration|
We are synthesizing graphene oxide on bio-material substrate (titanium) on atmospheric plasma treatment. This technique is simple and direct as compared to CVD and graphite expoliation. Reason behind using titanium as a substrate is that it is non toxic, bioinert, corrosoin resistance, low density and has intrinsic bio-compatibility. It needs some surface treatment or coating to enhance its cells interaction, osteoblast bone regeneration. Graphene oxide is chosen as a coating material because It is easier and cheaper to synthesize as compared to graphene. Carbon nanotubes are not chosen as a coating material because they are not good for cells viability. By raman spectroscopy we are pretty sure that both graphene and graphene oxide are successfully synthesized and further we will check its effect on osteoblast bone regeneration and cells viabilty.
|Alam Khurshed, Hoonsung Cho||Master course|
|6-10||8:40:30 PM||Jinhui SER||Anticancer effects of tannic acid-protamine conjugation on cells|
Tannins are polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. Tannic acid is contained in the wine and is known to combine with the mucous membrane proteins present in the tongue to produce a tangy taste. And the efficacy of tannic acid is anticancer and antioxidant, antibacterial, antiperspirant. Sp, anticancer effect of tannic acid is made only in the cell membrane, and it binds with the protamine which can enter into the cell, so that it enters the cell together. Finally, the purpose of the study is to identify whether the TA-Pro compound can attached to cell nucleus by attaching a fluorescent dye and confirming the anticancer effect.
|Jinhui Ser, Hoonsung Cho||Master course|
|6-11||8:45:00 PM||Raveendran ATHIRA||Effects of protamine conjugated with zw800-1 on cancer cells|
A cell penetrating peptide protamine when conjugated with a fluorescent dye zw800-1[zwitterionic near infrared fluorescent dye] is introdued to both HT29 human colon cancer cells and l929 fibroblast cells to check the cytotoxicity of dye on both cancer cells and normal cells.
|Raveendran Athira, Hoonsung Cho||Integrated course|