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ENGINEERING CHEMISTRY

(24CH101)

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Table of Contents

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Table of Contents

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COURSE OBJECTIVES

Objectives:

• To gain a comprehensive knowledge on polymers utilized in various industrial sectors.

• To acquire knowledge on the fundamental principles of energy storage devices.

• To gain insights into the basic concepts and applications of chemical sensors and cheminformatics.

• To identify the different types of smart materials and explore their applications in Engineering and Technology.

• To assimilate the preparation, properties and applications of nanomaterials in various fields.

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Pre-requisites�

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UNIT II ENERGY STORAGE DEVICES AND GREEN FUEL 9

• Introduction to Electrochemical cell and its terminology - electrochemical series and its applications.
• Batteries: classification - construction and working principle -primary alkaline battery - secondary battery - Pb-acid battery.
• Green fuel – Hydrogen - production (Photo electrocatalytic and photo catalytic water splitting), construction, working principle and applications in H₂- O₂ fuel cells.
• Batteries used in E-Vehicle: Ni-metal hydride battery, Li-ion Battery - recycling of Li-ion batteries by direct cycling method; environmental effects of different energy storage devices.

------------------------------------------------------------------LAB EXPERIMENTS: 6

1. Construction of electrochemical cell.

2. Determination of discharging state of Pb-acid battery by estimating the strength of the acid correlates with specific gravity.

3. Study of performance of a battery using battery analyzing module.

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24CH101-ENGINEERING CHEMISTRY L T P C 3 0 2 4

COURSE OUTCOMES

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Program Outcomes (POs)

PO1: Engineering Knowledge: Apply knowledge of mathematics, natural science, computing, engineering fundamentals and an engineering specialization as specified in WK1 to WK4 respectively to develop to the solution of complex engineering problems.

PO2: Problem Analysis: Identify, formulate, review research literature and analyse complex engineering problems reaching substantiated conclusions with consideration for sustainable development. (WK1 to WK4)

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PO3: Design/Development of Solutions: Design creative solutions for complex engineering problems and design/develop systems/components/processes to meet identified needs with consideration for the public health and safety, whole-life cost, net zero carbon, culture, society and environment as required. (WK5)

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PO4: Conduct Investigations of Complex Problems: Conduct investigations of complex engineering problems using research-based knowledge including design of experiments, modelling, analysis & interpretation of data to provide valid conclusions. (WK8).

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PO5: Engineering Tool Usage: Create, select and apply appropriate techniques, resources and modern engineering & IT tools, including prediction and modelling recognizing their limitations to solve complex engineering problems. (WK2 and WK6)

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PO6: The Engineer and The World: Analyse and evaluate societal and environmental aspects while solving complex engineering problems for its impact on sustainability with reference to economy, health, safety, legal framework, culture and environment. (WK1, WK5, and WK7).

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PO7: Ethics: Apply ethical principles and commit to professional ethics, human values, diversity and inclusion; adhere to national & international laws. (WK9)

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PO8: Individual and Collaborative Team work: Function effectively as an individual, and as a member or leader in diverse/multi-disciplinary teams.

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PO9: Communication: Communicate effectively and inclusively within the engineering community and society at large, such as being able to comprehend and write effective reports and design documentation, make effective presentations considering cultural, language, and learning differences

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PO10: Project Management and Finance: Apply knowledge and understanding of engineering management principles and economic decision-making and apply these to one’s own work, as a member and leader in a team, and to manage projects and in multidisciplinary environments.

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PO11: Life-Long Learning: Recognize the need for, and have the preparation and ability for i) independent and life-long learning ii) adaptability to new and emerging technologies and iii) critical thinking in the broadest context of technological change. (WK8)

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Knowledge and Attitude Profile (WK)

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WK1 : A systematic, theory-based understanding of the natural sciences applicable to the

discipline and awareness of relevant social sciences.

WK2 : Conceptually-based mathematics, numerical analysis, data analysis, statistics and formal aspects of computer and information science to support detailed analysis and modelling

applicable to the discipline.

WK3 : A systematic, theory-based formulation of engineering fundamentals required in the

engineering discipline.

WK4 : Engineering specialist knowledge that provides theoretical frameworks and bodies of

knowledge for the accepted practice areas in the engineering discipline; much is at the

forefront of the discipline.

WK5 : Knowledge, including efficient resource use, environmental impacts, whole-life cost, re-use of resources, net zero carbon, and similar concepts, that supports engineering design and

operations in a practice area.

WK6 : Knowledge of engineering practice (technology) in the practice areas in the engineering

discipline.

WK7 : Knowledge of the role of engineering in society and identified issues in engineering practice in the discipline, such as the professional responsibility of an engineer to public safety and sustainable development.

WK8 : Engagement with selected knowledge in the current research literature of the discipline,

awareness of the power of critical thinking and creative approaches to evaluate emerging

issues.

WK9 : Ethics, inclusive behavior and conduct. Knowledge of professional ethics, responsibilities, and norms of engineering practice. Awareness of the need for diversity by reason of ethnicity, gender, age, physical ability etc. with mutual understanding and respect, and of inclusive attitudes.

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Course Outcome mapping with POs / PSOs �

LECTURE PLAN

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LECTURE PLAN

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Activity Based Learning

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Concept

a) Series Connection

How: Positive terminal of one battery connects to the negative terminal of the next.

Effect: Voltages add up, capacity (mAh) stays the same as one cell.

Formula:

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Example: Two 1.5 V AA batteries in series → total voltage = 3 V.

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b) Parallel Connection

How: Positive terminals are connected together, negative terminals are connected together.

Effect: Voltage stays the same, capacities add up.

Formula:

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Example: Two 1.5 V AA batteries in parallel → total voltage = 1.5 V, capacity doubles.

Activity Demonstration

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Series vs Parallel Connection – Demonstrate how connecting batteries in series increases voltage, while parallel increases capacity.

UNIT – II�ENERGY STORAGE DEVICES �AND �GREEN FUEL�

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2.1 Introduction

The branch of science which deals with the relationship between chemical energy and electrical energy is called electrochemistry. It deals with chemical reactions that involve an exchange of electric charges between two substances. These reactions are called as electrochemical reactions. During the electrochemical reactions, either the chemical change generates electric current or the passage of electricity triggers chemical reactions. Thus, these electrochemical reactions undergo oxidation-reduction during the conversion.

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2.2 Terminology

2.2.1 Electrical Conductance: Electrical conductance is just the opposite of resistance, while resistance measures the opposition of the flow of electrons through it by a material. The electrical conductance is the measure of the property of a material by which it allows the electrons or electricity to pass through it. Substances behave differently in the presence of an electric current. All the substances do not conduct electric current.

2.2.2 Conductors: The substances which allow the passage of electric current are known as conductors. E.g. Metals, acids and bases. The capacity of a material to conduct current is known as conductance.

2.2.3 Insulators: The substances which do not allow the passage of electric current through them are known as insulators. E.g. Rubber, wood and plastic.

Types of conductors: The conductors are broadly classified into two types.

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2.2.4 Metallic conductors:

These are metallic substances which allow the electricity to pass through them without undergoing any chemical change. E.g. copper, silver, etc. The flow of electric current through a metallic conductor is due to the flow of electrons in the metal atoms.

2.2.5 Electrolytic conductors:

• The substances which allow electricity to pass through them in their molten state or in the form of their aqueous solutions are called as electrolytic conductors. During the passage of current, they undergo chemical decomposition. The conduction through electrolytes is due to the movement of ions.
• ELECTROLYTES: It is a substance that produces an electrically conducting solution, when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent. Electrically, such a solution is neutral. E.g. Acids, bases and salts are electrolytes.

2.2.6 Differences between Metallic conduction and Electrolytic conduction

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2.2.7 Cell terminology

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2.2.7 Conductance of electrolytes:

• Conductance is a property of electrolytic solutions which indicates how well an electrolyte can conduct electricity. It is defined as the conducting power of all the ions present in the electrolytic solution. Its value is numerically equal to the reciprocal of the resistance to the flow of electricity through the solution. i.e. C = 1/R.
• The unit of conductance is S (Seimen) or Ω^-1(ohm^-1) or mho. The conductance of an electrolyte is directly proportional to the surface area, a, of the electrodes, and inversely proportional to the distance between the electrodes, ℓ. i.e.
• C α a/ℓ ;
• C = k a/ℓ ,
• where k (Kappa) is called specific conductance (or conductivity).

2.3 Types of cells:

• A cell is a device consisting of two half cells. Each half cell consists of an electrode dipped in an electrolytic solution. The two types of cells are,

1. Electrolytic cells

2. Electrochemical cells (or) voltaic cells (or) galvanic cells

2.3.1 Electrolytic cell: It is a device that is used to convert electrical energy into chemical energy. In an electrolytic cell, a non-spontaneous redox reaction is made to take place through the application of electrical energy. Eg. Hydrolysis of water, electro refining, etc,.

2.3.2 Electrochemical cell (or) galvanic cell:

It is a device that is used to convert chemical energy into electrical energy. Certain chemical reactions take place spontaneously and produce electricity at appropriate operating conditions.

E.g. Daniel cell, dry cell etc.

Construction of Daniel cell:

• It consists of a Zn electrode dipped in 1M ZnSO₄ (anodic half cell) solution and a Cu electrode dipped in 1M CuSO₄ (cathodic half cell) solution. Both the half-cells are connected by a salt bridge.

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Reactions occurring in the cell:

• At anode: Oxidation takes place on the zinc electrode
• At cathode: Reduction takes place on the copper electrode

At anode – oxidation reaction (i.e)

At cathode – reduction reaction (i.e)

The net reaction is

Cell is representation: Zn_(s) / Zn²⁺_(aq) // Cu²⁺_(aq) / Cu_(s)

• The electrons released at anode flow through the external wire and are consumed by the copper ions at the cathode.

Salt bridge:

It consists of a U-tube containing saturated solution of KCl or NH₄NO₃ in agar-agar gel. It connects the two half cells of the galvanic cells. It maintains electrical neutrality within the internal circuit. If no salt bridge were present, the solution in one-half cell would accumulate a negative charge and the other half-cell would accumulate a positive charge as the reaction proceeds, quickly preventing further reaction.

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Functions of the salt bridge:

• Its main function is to prevent the potential difference that arises between the two solutions when they are in contact with each other. This potential difference is called liquid junction potential.
• It maintains electrical continuity of the solutions in the two half cells.
• It prevents the diffusion of solutions from one half cell to the other.
• It completes the electrical circuit by connecting the electrolytes in the two half cells.

2.3.1.3 Differences between electrolytic cells and electrochemical cells:

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The series of few elements are given in the table:

2.4 Electrochemical series and its significances:

The standard electrode potential (reduction) of a number of electrodes in salt solutions are given in table. These values are determined potentiometrically by combining the electrodes with the standard electrode, whose electrode potential is zero.

Definition:

• The arrangement of various electrodes in the increasing order of their standard reduction potential (using SHE as reference electrode) is known as emf (or) electrochemical series.

Applications of emf series (or) significances of

Electrochemical series:

The electrochemical series is an important tool in electrochemistry used for understanding and predicting the behavior of different elements and compounds in redox reactions, electrochemical cells, corrosion processes, and many other applications. Here’s how the electrochemical series is used in various aspects of electrochemistry:

1. Standard EMF of a cell (E^o):

The standard emf of a cell can be calculated, if the standard electrode potential values are known using the following relation.

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2. Relative ease of oxidation (or) reduction:

• Metals at the top of the series undergo easy oxidation; metals at the bottom of the series undergo easy reduction.
• a. The fluorine has (+2.87 V) higher positive value standard reduction potential and shows higher tendency towards reduction.
• b. The lithium has (-3.01 V) higher tendency towards oxidation.

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3. Anodic (or) cathodic behavior of metal:

• Metals lying higher in the series are anodic (more prone to corrosion) and metals lying lower in the series are cathodic (noble metals).

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4. Hydrogen displacement behavior:

• Metals with negative reduction potential will displace H₂ from an acid solution.

E.g. (E^o _Zn = -0.76 V)

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• Metal with positive reduction potential will not displace the H₂ from an acid solution. (E^o_Ag = +0.80 V)

5. Replacement tendency of one element by another:

• The metals that have a higher position in emf series can displace the metals which have a lower position in the emf series from their solution.

E.g. Zn(s) + CuSO₄ ZnSO₄ + Cu (s)

• Since zinc is placed above copper in emf series, zinc can replace copper from the copper solution.

6. Predicting the spontaneity (or) feasibility of a redox reaction:

• If the net emf E^o of the cell is positive, the reaction is feasible (or) spontaneous (ΔG^o = -ve). But if the net E^o of the cell is negative, the reaction is not feasible (or) non spontaneous (ΔG ^o= +ve).

E.g. For Daniel cell

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Therefore the reaction is feasible.

7. Determination of standard free energy (ΔG^o) and equilibrium constant for the reaction:

• EMF series is used to determine the standard free energy change (ΔG^o) and equilibrium constant (K) for the reaction. We know that, from the value of E^o, the equilibrium constant for the cell reaction can be calculated.

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2.5 Energy storage devices

2.5.1. Introduction:

Energy storage devices, such as batteries, supercapacitors, and fuel cells, are essential components of modern technology and are directly related to electrochemistry. Electrochemistry deals with the interconversion of chemical energy and electrical energy through redox (reduction-oxidation) reactions, which are fundamental to the operation of these devices. Here's an overview of how different types of energy storage devices function and their role in electrochemistry:

Energy storage is the capture of energy produced at one time and can be used later. A device that stores energy is generally called as an accumulator or battery. Energy comes in multiple forms including radiation, chemical, gravitational potential, electrical potential, electricity, elevated temperature, latent heat and kinetic. Various types of energy storage devices are fuel cells, batteries, capacitors, flywheels, compressed air, pumped hydro, super magnets, hydrogen, etc. 

2.5.2 History of battery:

Batteries have been with us for a long time. In 1938, the Director of the Baghdad Museum found the “Baghdad Battery” in the basement of the museum. During its analysis, it is dated around 250 BC and it is of Mesopotamian origin.

American scientist and inventor Benjamin Franklin first used the term "battery" in 1749 when he was doing experiments with electricity using a set of linked capacitors.

The first true battery was invented by the Italian physicist Alessandro Volta in 1800. Volta stacked discs of copper (Cu) and zinc (Zn) separated by cloth soaked in salty water.

Some of the first practical batteries used are:

• Daniel cell
• Bird’s cell
• Porous pot cell
• Gravity cell
• Poggendorff cell
• Grove cell
• Dun cell

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One of the most enduring batteries, the lead-acid battery, was invented in 1859 and is still the technology used to start most internal combustion engine cars today. It is the oldest example of rechargeable battery. Later scientists found so many rechargeable batteries such as Nickel-cadmium battery, lithium and lithium-ion batteries etc.,

Electrochemical Cell is a device that converts chemical energy into electrical energy. Wherever energy is needed, chemical reactions can be made to occur in the cell.

A battery is basically an electrochemical cell which is an arrangement of several electrochemical cells connected in series. These are devices that give direct current, maintaining a constant voltage. The battery's voltage is equal to the voltage of one cell multiplied by the number of such cells connected in series. In the battery the cells are arranged in such a way that the anode of one cell is connected to the cathode of the other cell.

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2.5.3 Requirements of a battery:

• The voltage of the battery should not vary appreciably during its use.
• It should be light and compact for easy transport.
• It should have long life both when it is in use and not in use.
• High overall efficiency.
• Very low self-discharge.
• Low maintenance cost.
• Easy installation and operation.

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2.6 Types of batteries:

Primary batteries:

In primary batteries, the electrode reaction cannot be reversed by passing an external electrical energy. The reactions occur only once and after use they become dead. Therefore they are not chargeable. Based on the standard size and capacity, they are classified as shown in figure below. E.g. Daniel cell, Dry or Leclanche cell.

2. Secondary batteries:

In this the electrode reactions can be reversed by passing an external electrical energy. Therefore they can be recharged by passing electric current and used again and again E.g. Pb-H₂SO₄ battery, Ni-Cad battery

3. Reserve battery or fuel cell:

Fuel cells are cells producing electrical energy from chemical energy produced out of the chemical reactions of different fuels. E.g. H2-O2 fuel cells.

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2.7. Primary Alkaline Batteries :

An Alkaline battery is an improved form of the dry cell in which the electrolyte NH₄Cl is replaced by KOH, which is having more positive potential. This fact led to the development of many alkaline batteries. Commercial Duracell batteries are examples of alkaline batteries.

Specifications of Alkaline Batteries:

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Construction and Working:

Alkaline battery is an improved form of the dry cell, in which the electrolyte NH₄Cl is replaced by KOH. Alkaline battery consists of a zinc cylinder filled with an electrolyte consist of powdered KOH and MnO₂ (active cathodic material) in the form of paste using starch and water. A carbon rod (cathode) is immersed in the electrolyte in the centre of the cell for electrical contact for the flow of electrons. The outer cylindrical zinc body acts as anode.

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Cell reaction:

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The emf of the cell is 1.5V.

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At anode : Zn_(s)+2OH^-_(aq) ⎯→ Zn(OH)_2(s)+2e^-

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At cathode : 2MnO_2(s)+H₂O_(l)+2e^- ⎯→ Mn₂O_3(s)+2OH^-_aq

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 Overall cell reaction:

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Zn_(s)+ 2MnO_2(s)+H₂O_(l) ⎯→ Zn(OH)_2(s)+ Mn₂O_3(s)

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Advantages of Alkaline batteries:

The main advantages of alkaline cell over dry cell are:

• There is no leakage, since Zn does not dissolve readily in a basic medium.
• The shelf life of alkaline battery is longer than the dry battery, because there is no corrosion of Zn. An alkaline battery is expected to power a device for a period of two to four months (except in a few low-drain applications).
• Alkaline battery maintains its constant voltage, as the current is drawn from it.
• Alkaline batteries are environment-friendly, which can be disposed as trash and do not require active collection and recycling.
• The Wide choice of batteries offered by the manufacturers according to the applications (low-drain, medium-drain and high-drain batteries) makes it more advantageous.

Uses:

• Applications of low-drain alkaline batteries include flashlights, portable radios, alarm clocks, remote controls, and toys etc.
• Medical applications use alkaline batteries as power source in specific types of infusion pumps, pulse oximeters, blood pressure monitors, electronic thermometers and the like.
• Industrial applications of alkaline batteries involve usage in smoke alarms, portable transmitters, scanners, digital voltmeters, door locks, remote controls and laser pointers.
• Military and defense application include usage of alkaline batteries in SINCGARS, man pack radios and also in GPS systems.

[Note: Single Channel Ground and Airborne Radio System (SINCGARS) is a Combat Net Radio (CNR) currently used by U.S. and allied military forces]

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2.8. Secondary batteries:

In this the electrode reactions can be reversed by passing an external electrical energy. Therefore they can be recharged by passing electric current and used again and again.

E.g. Pb-acid battery, Ni-cad battery

2.8.1. Lead-Acid Storage Batteries:

The lead-acid battery represents the oldest rechargeable battery technology. Lead-acid batteries can be found in a wide variety of applications, including small-scale power storage such as UPS systems, starting, lighting, and ignition power sources for automobiles, along with large, grid-scale power systems. Recently, significant improvements in the cycle life of lead-acid batteries have been achieved through the incorporation of carbon into the negative plate. Carbon modification has provided new life to ageing lead-acid battery technology, enabling its use in hybrid vehicles as well as stationary storage.

A lead-acid storage cell is a secondary battery, which can operate both as a voltaic cell and as an electrolytic cell. This is the most commonly used battery in all automobiles to give power to the Ignition circuit.

Specifications of Lead-Acid Storage Batteries:

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Description:

A lead-acid storage battery consists of a number of voltaic cells (3-6) connected in series. In each cell the anode is made of lead. The cathode is made of lead dioxide PbO₂ or a grid made of lead, packed with lead dioxide. A number of lead plates (anodes) are connected in parallel and a number of PbO₂ plates (cathodes) are also connected in parallel. The plates are separated by an insulator made up of rubber, wood or fiberglass. The entire combination is then immersed in dilute H₂SO₄ (38% by mass).

The cell may be represented as:

Pb/PbSO₄ // H₂SO₄(aq) // PbO₂ / PbSO₄

Cell reactions: Discharging

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At anode: Lead is oxidized to Pb²⁺ ions, which further combines with SO₄^2- forms insoluble PbSO₄.

Pb_(s) ↔ Pb²⁺_(aq) + 2e⁻

Pb²⁺_(aq)+SO₄²⁻_(eq) ↔ PbSO₄

Over all anode reaction: Pb_(s) + SO₄²⁻ ↔ PbSO_4(s) + 2e⁻

At cathode: PbO₂ is reduced to Pb²⁺ ions, which further combines with SO₄^2- forms insoluble PbSO₄.

PbO_2(s) + 2e⁻ + 4H⁺_(aq) ↔ Pb²⁺_(aq) + 2H₂O_(l)

Pb²⁺_(aq) +SO₄²⁻_(aq) ↔ PbSO_4(s)

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Over all cathode reaction: PbO_2(s) + 2e⁻ + 4H⁺_(aq) + SO₄²⁻_(aq) ↔ PbSO_4(s) + 2H₂O_(l)

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Overall cell reaction:

Pb_(s) + PbO_2(s) + 2H₂SO_4(aq) ↔ 2PbSO_4(s) + 2H₂O_(l)

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From the above cell reactions it is clear that PbSO₄ is precipitated at both the electrodes and H₂SO₄ is used up. As a result, the concentration of H₂SO₄ decreases so the battery needs recharging and also needs water, to compensate evaporation loss.

Recharging the battery:

The cell can be charged by passing electric current in opposite direction. The electrode reaction gets reversed. As a result Pb is deposited on anode and PbO₂ on the cathode. The density of H₂SO₄ also increases.

The net reaction during charging is

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Net cell reaction during both charging and discharging is

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Advantages:

• Inexpensive and simple to manufacture. 
• Mature, reliable and well-understood technology - when used correctly, lead-acid is durable and provides dependable service.
• The self-discharge is among the lowest of rechargeable battery systems.
• It produces very high current (Capable of high discharge rates).
• It acts effectively at low temperatures.

Disadvantages:

• Low energy density - poor weight-to-energy ratio limits use to stationary and wheeled applications.
• Cannot be stored in a discharged condition - the cell voltage should never drop below 2.10V.
• Allows only a limited number of full discharge cycles - well suited for standby applications that require only occasional deep discharges.
• Lead content and electrolyte make the battery environmentally unfriendly. 
• Transportation restrictions on lead acid batteries as there are environmental concerns regarding spillage.
• Thermal runaway can occur if improperly charged.
• It is too heavy for handling and also leaks at times

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Applications:

1. The cell is used for automobile starting, lighting and ignition batteries.

2. It is used in large backup power supplies for telephone and computer centers, grid energy and off-grid household electric power systems.

3. They are used in backup power supplies for computer systems.

4. They are used as fuel in electric scooters, electric wheel chairs, electrified bicycles, marine applications, battery electric vehicles or micro hybrid vehicles, and motorcycles.

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2.9 Green fuel

A green fuel is a type of fuel that is produced from renewable sources and has a low impact on the environment. It is designed to reduce greenhouse gas emissions and other pollutants compared to conventional fossil fuels. Green fuels are essential for mitigating climate change and promoting sustainability.

Examples of Green Fuels: Hydrogen, Biofuels, Methanol, Renewable Natural Gas or Biomethane

Characteristics of Green Fuels

• Low Emissions:

Significantly lower greenhouse gas emissions compared to fossil fuels.

Reduced air pollutants such as nitrogen oxides (NO_x), sulfur oxides (SO_x), and particulate matter.

• Renewable Sources:

Derived from renewable resources that can be replenished naturally, such as plants, organic waste, sunlight, and wind.

• Sustainability:

Promotes sustainable practices by reducing dependency on finite fossil fuel resources and minimizing environmental impact.

• Carbon Neutrality:

Green fuels, particularly biofuels, can achieve carbon neutrality by balancing the carbon dioxide (CO₂) released during combustion with the CO₂ absorbed during the growth of the biomass feedstock.

• Energy Efficiency:

Many green fuels have high energy efficiency, making them viable alternatives to traditional fossil fuels.

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2.10 Hydrogen as fuel

Hydrogen is a green fuel due to its potential for sustainable production and its environmentally friendly combustion, producing only water as a byproduct. It can play a critical role in reducing greenhouse gas emissions and transitioning to a clean energy future.

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Characteristics of Hydrogen as a Fuel

a) Zero Emissions:

When used in fuel cells or burned, hydrogen produces water vapour (H₂O) as the only emission, with no carbon dioxide (CO₂) or other pollutants.

b) High Energy Density:

Hydrogen has a high energy content per unit mass, making it an efficient energy carrier.

c) Versatility:

Hydrogen can be used in various applications, including transportation, power generation, and industrial processes.

d) Renewable Production Potential:

Hydrogen can be produced using renewable energy sources, making it a sustainable alternative to fossil fuels.

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Need for Renewable Pathways in Energy

Reduce Pollution: Renewable energy sources like solar, wind, hydro, and biomass produce little to no harmful emissions, improving air quality and public health.

Save Natural Resources: Unlike coal, oil, and natural gas, renewable sources are abundant and naturally replenished, ensuring long-term energy availability.

Enhance Energy Security: Using locally available renewable resources reduces dependence on imported fuels, making countries less vulnerable to supply disruptions and price fluctuations.

Fight Climate Change: Switching to renewables significantly lowers greenhouse gas emissions, helping slow global warming and meet international climate targets.

Support Sustainable Growth: Renewable energy promotes eco-friendly development that balances economic growth with environmental protection for future generations.

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Advantages of PEC Hydrogen Production

1. It Utilizes abundant solar energy and water as inputs, making it an environmentally friendly method.

2. The Potential for high solar-to-hydrogen conversion efficiency with advancements in materials and system designs.

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2.10.2 Photocatalytic Water Splitting Process:

This process splits the water into hydrogen and oxygen in the presence of catalyst and natural light(sunlight). In this process, photocatalyst plays a crucial role. The semiconducting material Titania (TiO₂) with Nitrogen(N) dopant has been widely used as a photocatalyst and Pt (deposit on surface) as a co-catalyst in photocatalytic water splitting process.

In photocatalytic water splitting, a semiconductor photocatalyst absorbs light energy to generate electron-hole pairs. These charge carriers then drive the redox reactions needed to split water molecules into hydrogen and oxygen.

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Mechanism:

There are three important steps involved in semiconductor photocatalysis are as follows,

1. Photon absorption: semiconductor photocatalyst material absorbs photons of energy greater 1.23eV. Electrons are photo excited and move from VB to CB creating electron hole pair.

2. Separation and Migration of Charge Carriers: Charge separation and migration of the photogenerated electron and hole separate and move to the surface.

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Photocatalyst TiO₂ / ZnO + hᵞ e^- + h⁺

Oxidation : H₂O + 2h⁺ 2H⁺ + ½ O₂

Reduction : 2H⁺ + 2e^- H₂

Overall reaction : H₂O + 1.23 eV H₂ + ½ O₂

The efficiency of the catalyst can be enhanced by including dopants or co-catalysts that include metal or metal oxides such as Pt, NiO and RUO₂ which can act as the active sites._. The dopant enhances the bandgap greater than 1.23 eV, or else the electrons will not have enough energy to start the reaction.

Advantages:

1. The set up is simple which contains a single photocatalyst material.

2. Both reduction and oxidation occur on the same photocatalyst surface.

3. The efficiency is limited by the recombination of electrons and holes.

3. Redox Reactions: Adsorbed water on the surface is reduced and oxidised by electrons and holes. The oxidation of water into O₂ and H⁺ occurs at photoanode by photo holes and at cathode the photogenerated electrons reduce H⁺ into H₂.

4. Redox Reactions:

The possible redox reactions on the surface of the photocatalyst are described by the following equations,

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2.10.1 Hydrogen Production through Photoelectrocatalytic (PEC) Method:

The concept of photo-electrocatalysis was first discovered by Fujishima – Honda dio in 1972, wherein they achieved water splitting utilizing a single crystal TiO_2. The photo-electrocatalytic (PEC) method of hydrogen production utilizes light energy to drive the water-splitting reaction, producing hydrogen and oxygen. This process involves the use of photoelectrodes that absorb sunlight and generate electron-hole pairs, which then facilitate the redox reactions needed for water splitting.

Experimental setup: Component

Electrode: Photoanode is made of semiconducting material (e.g., TiO₂, Fe₂O₃, WO₃) deposited on a conductive substrate like fluorine-doped tin oxide (FTO) glass. Counter Electrode is made of platinum (Pt) due to its excellent catalytic properties for hydrogen evolution.

Electrolyte Solution: Aqueous solution, commonly used electrolytes include potassium hydroxide ( 1M KOH) or sulfuric acid (0.5M H₂SO₄) are taken in glass or quartz container to allow light penetration. The choice of electrolyte depends on the stability and compatibility with the photoanode material.

Light Source: Solar simulator to mimic sunlight or direct sunlight.

Gas Collection System: These gases are collected using gas collection tubes or water displacement methods. The volumes of hydrogen and oxygen gases produced are measured to determine the efficiency of the process.

Working: The overall photocatalytic dissociation of water consists of mainly three steps and a side reaction:

(1) electron–hole pair’s generation by using the absorption of a photon,

(2) electron–hole separation and migration of electrons to the conduction band,

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(3) reactions between surface species and electron

(4) Recombination of hole and electron (side reaction)

Oxidation Reaction at Photoanode:

On absorbing photons semiconductor produces electron hole pair. Holes at the photoanode oxidize water to produce oxygen gas (O₂), protons (H⁺), and electrons.

n type semiconductor + 4hᵞ n type semiconductor (4e^-+4h⁺)

2H₂O +4hᵞ(VB) O₂​+4H⁺+4e⁻

Reduction Reaction at Photocathode:

The electrons travel through an external circuit to the counter electrode (platinum). The protons (H⁺) produced at the photoanode migrate through the electrolyte to the counter electrode. Hydrogen gas (H₂) is produced at the counter electrode.

4H⁺+4e⁻ (CB) 2H₂​

Overall water-splitting Reaction:

2H₂​O+4hᵞ 2H₂​+O₂​​

Significance of Photoelectrocatalytic (PEC) Hydrogen Production

1. Clean Energy Production: This process produces zero emission. Utilizes abundant and renewable resources—solar energy and water

2. It helps in sustainable hydrogen economy

3. Reduces Fossil Fuel Dependence.

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Difference between Photocatalytic and Photo-electrocatalytic Water Splitting

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2.11. Fuel cells:

Fuel cell is a device that converts the chemical energy of a fuel directly into electricity by electrochemical reactions. A fuel cell resembles a battery in many respects, but it can supply electrical energy over a much longer period of time, because a fuel cell is continuously supplied with fuel and air (or oxygen) from an external source. Hence, fuel cells have been used for decades in space probes, satellites, and manned spacecraft. Around the world thousands of stationary fuel cell systems have been installed in utility power plants, hospitals, schools, hotels, and office buildings for both primary and backup power; many waste-treatment plants use fuel cell technology to generate power from the methane gas produced by decomposing garbage.

Fuel + oxygen → oxidation products + Electricity

Different types of fuel cells are

• Polymer electrolyte membrane fuel cells
• Direct methanol fuel cells
• Alkaline fuel cells
• Phosphoric acid fuel cells
• Molten carbonate fuel cells
• Solid oxide fuel cells
• Reversible fuel cells

2.11.1. Hydrogen – Oxygen Fuel Cell:

Hydrogen-oxygen fuel cell is the simplest and most successful fuel, which uses the fuel hydrogen and the oxidizer-oxygen with the electrolyte. Other fuels include hydrocarbons and alcohols. Other oxidants include chlorine and chlorine dioxide. The cell releases the energy from hydrogen by reacting with oxygen, not as heat as in normal combustion with air, but as useful electrical energy i.e. a practical electricity supply.

Specifications of H₂- O₂ Fuel Cell:

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Construction:

The cell has two porous electrodes, anode and cathode. The electrodes are made of compressed carbon containing a small amount of catalyst (Pt,Pd,Ag) impregnated in it. In between the two electrodes an electrolyte solution such as 25% KOH or NaOH is filled. The two electrodes are connected through the voltmeter.

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Working of the cell:

The fuel hydrogen is bubbled through the anode compartment, where it is oxidized. The oxidizer oxygen is bubbled through the cathode compartment, where it is reduced.

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At Cathode: The electrons, produced at the anode, pass through the external wire to the cathode where it is absorbed by oxygen and water to produce hydroxide ions.

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Overall cell reaction:

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The emf of the cell = 1.0 V

Fuel Battery:

When a large number of fuel cells are connected in series, it forms a fuel battery.

Advantages of fuel cells:

• Fuel cells are efficient (75%) and take less time for operation.
• It is pollution and noise free technique.
• It produces electric current directly from the reaction of fuel and an oxidizer.
• It produces drinking water.

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Cell Reactions :

• At anode: Hydrogen gas, passed through the anode, is oxidized with the liberation of electrons which then combine with hydroxide ions to form water.

5. Hydrogen-oxygen fuel cells are much efficient than conventional power stations or batteries (e.g. zinc-carbon) because the electrical energy is directly generated from the chemical reaction between the oxidant and the fuel - there are no complications like turbines and generators.

6. With a fuel cell there are fewer stages in producing the useful energy, so there is less opportunity to lose potentially useful energy i.e., like wastage of heat, friction from moving parts etc.

7. They are highly efficient in energy conversion and instant in operation.

8. Fuel cell holds promises in the energy scenario, replacing to some extend fossil fuel.

Disadvantages:

1. Fuel cells cannot store electric energy as other cells do.

2. Electrodes are expensive and short lived.

3. Storage and handling of hydrogen gas is dangerous.

4. High initial cost.

5. Large weight and volume of H₂ and O₂ gas storage.

6. Porous electrodes are affected by CO₂ hence gases should be free from CO₂.

7. H₂ should be pure.

Applications:

• H₂- O₂ fuel cells are used as auxiliary energy source in space vehicles like Apollo space program and also in submarines.
• The product water is proved to be a valuable source of fresh water by the astronauts.

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3. Currently, extensive research is being conducted in order to manufacture a cost efficient automobile which is powered by a fuel cell.

4. Fuel cell electric vehicles use clean fuels and are therefore more eco-friendly than internal combustion engine-based vehicles.

5. Generally, the byproducts produced from these cells are heat and water.

6. The portability of some fuel cells is extremely useful in some military applications.

7. These electrochemical cells can also be used to power several electronic devices.

8. Fuel cells are also used as primary or backup sources of electricity in many remote areas.

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2.12 E- Vehicles

The major air pollution specifically in cities are caused by passenger vehicles. They let out tail pipe pollutants like carbon monoxide, nitrogen oxides and other pollution. In addition the transport sector is responsible for about 28% of the total carbon dioxide (CO₂) , a green house gas emissions as per European union report, On the other hand limited oil reservoirs pressurises research and government to take an alternative steps to address the problems. The alternative solution provided by researcher and action taken by government is to shifting towards e vehicle. The advantages of e-vehicle are

1. Zero emissions: The combustion product like CO₂ and NO₂ is eliminated from vehicles. The chemical reaction in batteries doesn’t lead to any emission of gases.

2. Simple Engine Design: The engines design is simple as neither need of a cooling circuit, nor for incorporation, clutch , gearshift, or elements to reduce the engine noise.

3. Increase in reliability: Simple engine technology hence fewer breakdowns.

4. Maintenance Cost: The maintenance cost much lower for EVs than conventional vehicle.

5. Comfort: The traveling in Evs is comfortable, due to the absence of vibrations or engine noise.

6. Efficiency: EVs fed by renewable energy show an higher overall efficiency up to 70% but EVs fed by a natural gas power plant show a the overall well to wheel WTW efficiency that ranges from 13% to 31.

E- Vehicle challenges and the area of improvement required:

1. Driving range is limited from 200 to 350 km with a full charge, although this issue is being continually improved. The Tesla Model S has shown a driving range greater than 500 km.

2. Full charging the battery pack can take 4 to 8 h. Even a “fast charge” to 80% capacity can takes 30 min. For example, Tesla super chargers can charge the Model S up to 50% in only 20 min, or 80% in half an hour.

3. Large battery packs are expensive and are heavy 200 kg and take up considerable vehicle space

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2.12.1. Nickel metal hydride battery (NiMH or Ni–MH):

It is a type of rechargeable battery. Stanford Ovshinsky is the inventor of NiMH battery. In view of the environmental fears about Nickel Cadmium batteries and cells, Nickel Metal Hydride technology has taken over. The first consumer-grade NiMH cells became commercially available in 1989. In 2008, more than two million hybrid cars worldwide were manufactured with NiMH batteries.

Specifications of Nickel metal hydride battery:

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Batteries used in E- vehicle

Description:

In this battery anode is porous nickel grid pasted with hydrides of metals like VH₂, ZrH₂ and TiH₂ with a hydrogen storage metal alloy such as TiN₂ or LaNi₅ (ie) hydrogen absorbing alloy is used as anode and cathode is nickel grid pasted with NiO(OH). The electrolyte is 28% KOH solution.

The cell representation is MH₂/M/KOH// NiO(OH)/Ni(OH)₂

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Working (Discharging):

When the NiMH battery operates the following reactions occur. NIMH system requires 10 series cells to reach potential of 12 V.

At Anode:

Metal hydride is oxidized with the liberation of electrons which then combine with hydroxide ion to form water.

MH_{2 (s)}+2OH^-_(aq) → M_(s) + 2 H₂O _(l)+2 e^-

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At Cathode:

Nickel oxyhydroxide is reduced to Ni²⁺ which further combine with H₂O to form Ni(OH)₂.

2 NiO(OH)_(s)+ 2 H₂O_(l)+ 2 e^- ↔ 2 Ni(OH)_2(l)+ 2 OH^-_(aq)

Overall cell reaction during use (discharging):

MH_{2 (s)} + 2 NiO(OH)_(s) ↔ M_(s)+ 2 Ni(OH)_2(l)

 Recharging the battery:

The cell can be charged by passing electric current in opposite direction. The electrode reaction gets reversed. As a result MH₂ is deposited on anode and NiO(OH) on the cathode. The density of KOH also increases.

2 Ni(OH)_{2 (l)} + M_(s) ↔ 2 NiO(OH)_(s) + MH_{2 (s)}

Advantages:

1. NiMH has less toxins and it is environment friendly.

2. It can be recycled.

3. It can be used in wide temperature range.

4. It has 30 – 40 percent higher capacity and energy density over a standard Ni-Cd battery.

5. It is much safer than lithium batteries.

6. It has less memory effects than nicad

Disadvantages:

1. More complex charge algorithm needed-NiMH generates more heat during charge.

2. This battery deteriorates during long time storage.

3. Deep discharge reduces the life cycle and produces heat when it is fast charged and high load discharge.

4. Self-discharge is more compared to other batteries.

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5. High maintenance is required, it should be often fully discharged to prevent crystalline formation.

6. Expensive than Ni-Cad battery.

Applications:

It is used in

• Low cost consumer applications.
• Electric vehicles.
• Space crafts.
• High power static applications.
• Commercial and industrial portable products.
• Medical instruments and equipment.
• Toys, cameras, mobile phones etc.,

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2.12.2. Lithium Batteries:

Chemists worked on the idea for the lithium battery in 1912, but first commercial Li battery was available only in 1970 and these batteries were not rechargeable. The chemical instability of lithium metal made rechargeable lithium batteries too difficult to develop. In 1991, scientists used more stable lithium compounds to create a battery. This lithium ion battery was rechargeable and lighter in weight than other rechargeable battery technologies available at the time.

There are two types of Lithium based batteries:

1. Lithium-Batteries:

Li-batteries are primary batteries that have metallic lithium as an anode and a reductive material as cathode . These types of batteries are also referred to as lithium-metal batteries.

ii) Lithium-ion batteries:

Li-ion batteries are secondary batteries that have Lithium compounds are used as cathode. Lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. Because of this reason, the lithium ion batteries are called Rocking chair, Swing cells.

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Comparison of Li and Li-ion batteries:

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1. Lithium batteries are a primary cell and lithium ion batteries are secondary cells.
2. Lithium batteries are not easily and safely rechargeable; this problem led to the invention of lithium ion batteries. They can be charged several times before becoming ineffective. 
3. Li batteries have a higher energy density than lithium ion batteries.
4. Lithium batteries use lithium metal as their anode unlike lithium ion batteries that use a number of other materials to form their anode.
5. Both types of batteries offer a lot of power for their size. They can be used in any number of devices from flashlights to compact disc players.
6. Their recharge ability makes them ideal power sources in consumer electronics.
7. Lithium batteries are the battery of choice when it comes to powering artificial pacemakers because of their long life and the amount of energy they offer.
8. Lithium batteries work well as long-term power sources in devices that are out of reach, such as smoke detectors and computer motherboards.

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Lithium - ion battery:

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The cell specification is as follows:

Construction:

Lithium ion secondary battery depends on an “intercalation” mechanism. This involves the insertion of lithium ions into the crystalline lattice of the host electrode without changing its crystal structure. Lithium ion batteries consist of a Lithium Metal Oxide positive electrode (cathode) with thin aluminum foil as current collector, graphite negative electrode (anode) and electrolyte of a lithium salt in alkyl carbonate solution.

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The cathode is made of transition metals oxides or phosphates as active material such as:

• Lithium Cobalt Oxide – LiCoO₂
• Lithium Iron Phosphate – LiFePO₄
• Lithium Manganese Oxide – LiMnO₂
• Lithium Nickel Manganese Cobalt Oxide – LiNi_xMn_yCo_zO₂

Li-ion cell has a four-layer structure. Cathode and anode are separated by a membrane made of polypropylene or polyethylene filled with electrolyte which contains lithium salts (i.e. LiPF₆) in ethylene or propylene carbonate at different ratio. The separator prevents the electrical contact between the electrodes and at the same time, it allows the diffusion of Li-ions from cathode to anode during the charging and the reverse discharging process.

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Working:

During discharge Li ions are dissociated from the anode (negative plate) and migrate across the electrolyte and are inserted into the crystal structure of the host compound of cathode.

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For example in Lithium Cobalt Oxide (LiCoO₂) the discharge mechanism is as follows:

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Advantages:

1. They produce high voltage about 4 V as compared with other batteries.
2. They have high energy density than other rechargeable batteries. ( 7g of Lithium produces one faraday of current)
3. Available in various shapes and sizes and lighter in weight.
4. There is no requirement for priming like in nickel batteries.
5. Do not suffer from memory effect.
6. They possess low self discharge rate (5–10% per month).
7. They are lighter than other battery types.

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8. No liquid electrolyte (i.e., they are immune from leaking)

9. Low maintenance cost.

Disadvantages:

1. They are expensive.
2. The capacity diminishes with charging and ageing.
3. Internal resistance increases with charging and ageing.
4. Undergo explosion when contacts with air/moisture.

Applications:

Lithium batteries have a long list of real-world applications, They are

1. Emergency Power Backup Or UPS (Uninterruptible Power Supply):

Emergency power backup systems benefit critical equipment, computers, communication technology and medical technology.

2. Solar Power Storage:

Lithium batteries used for solar power storage.

3. Dependable Electric And Recreational Vehicle Power:

With a lifespan of over ten years, lithium batteries provide power for long journeys. Lightweight lithium batteries power electric vehicles with increased efficiency due to reduced weight and size as compared to lead acid batteries.

4. Reliable And Lightweight Marine Performance:

Long-lasting rechargeable lithium battery power a small trolling motor or power all of the conveniences of home on a yacht.

5. Mobility Equipment:

Lightweight lithium batteries are the ideal choice for mobility equipment, from electric wheelchairs to stair lifts. They offer size customization, a longer life span, fast charging, a low self-discharge rate and extended run time.

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6. Portable Power Packs:

Rechargeable lithium batteries are well-known for powering our phones and the latest lightweight laptop computers. They tolerate movement and temperature changes, as well as maintain their power delivery during use.

7. The Li-ion batteries are used in cameras, calculators.
8. They are used in cardiac pacemakers and other implantable device.

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2.13 Direct Recycling Method for Lithium-Ion Batteries

Direct recycling methods for lithium-ion batteries and other types of batteries typically involve several key steps. The aim is to efficiently restore and reuse battery components while minimizing processing and preserving material quality

steps involved in direct recycling:

1. Collection and Sorting

Gather used batteries from various sources, including consumer electronics, electric vehicles, and industrial applications. Separate batteries based on type, chemistry, and condition to ensure appropriate recycling methods are applied.

2. Discharge and Safety Handling

Discharge lithium-ion batteries by safely draining their charge using controlled discharging equipment, and handle with care to prevent leaks or short circuits, using protective gear and proper containment.

3. Dismantling and Component Removal

Open and dismantle battery packs or cells to access individual components such as electrodes, separators, and electrolyte materials.

4. Cleaning and Preparation

Remove contaminants from the electrodes by washing with solvents or using ultrasonic cleaning and they are dry and free from residues.

5. Direct Recycling of Process:

1. Direct Recycling of Cathodes

a. Thermal Regeneration Process: It is carried out by the following techniques:

Hydrothermal Treatment: Utilizes high-temperature steam under pressure to clean and rejuvenate cathode materials. This method can help in restoring the crystal structure of the cathode material.

Calcination: Involves heating the cathode material in the presence of air or oxygen to remove organic impurities and residues. This process helps in stabilizing the crystal structure of the active material.

Advantages: Preserves the integrity of the cathode material, potentially improving performance.

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b. Chemical Treatments

It is carried out by the following techniques:

• Acid Leaching: Utilizes acids (e.g., sulfuric acid, hydrochloric acid) to dissolve and remove contaminants and recover valuable metals like cobalt, nickel, and lithium from the cathode material.
• Solvent Extraction: Employs organic solvents to selectively extract and purify metals from the cathode material. This process can also help in separating and recovering different metals.

Advantages: Effective in purifying and recovering valuable metals, and can be tailored to specific battery chemistries.

c. Electrochemical Methods

1. Electrochemical Reduction: This method targets the restoration of oxidized cathode materials. During the process, an electrochemical current is applied to reduce metal ions in the cathode back to their original, more active state. For example, lithium cobalt oxide can be converted back to its reduced form, improving its electrochemical properties and performance.

2. Electrochemical Re-deposition: In this technique, metal ions like nickel, cobalt, or lithium are deposited back onto the electrode surfaces from a solution. This process helps in regenerating the active materials on the electrodes, allowing for their reuse in new battery cells. By re-depositing these metals, the process not only recovers valuable materials but also restores the electrode's functionality.

3. Electrolyte Treatment: Electrochemical methods can also be applied to rejuvenate electrolytes. By treating used electrolytes through electrochemical processes, their conductivity and stability can be improved, making them suitable for reuse.

Advantages: Can directly restore the electrochemical properties of the cathode material.

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Direct Recycling of Anodes

a. Thermal Regeneration

It is carried out by the Graphitization techniques. It Involves heating the graphite anode material to very high temperatures to enhance its graphitic structure, which is crucial for battery performance.

Advantages: Preserves the essential graphitic structure, crucial for maintaining high performance.

b. Mechanical Treatment

Anodes are crushed into smaller pieces, then ground into fine powders. Sieving sorts these powders by size to isolate valuable components like lithium, cobalt, and graphite for further processing.

c. Chemical Reconditioning

Acid Wash: This method employs diluted acids to effectively dissolve and eliminate impurities from the anode material, thereby enhancing its purity.

Solvent Wash: Organic solvents are used to clean the anode material, targeting and removing organic residues and contaminants.

6. Reassemble Cells: For reusable electrodes and components, reassemble them into new battery cells or packs. This may involve integrating restored electrodes with new electrolyte and separators.

Direct recycling systematically recovers and reuses battery components, emphasizing material restoration and waste reduction to improve recycling efficiency and sustainability.

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2.14 Environmental effects of different energy storage devices

Practice Quiz

Unit II:

https://docs.google.com/forms/d/e/1FAIpQLSeEuHNFieDTRs06kZBihm9Vuf2jRB9DwHNctdfWXwTxdGoYIg/viewform?usp=sf_link

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2.1 Assignment

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2.2 Assignment

2.3 Assignment

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2.4 Assignment

2.5 Assignment

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Part-A Question and Answer

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Part-A Question and Answer

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Part-B Questions

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Supportive online certification courses

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1. Hydrogen Energy Production, Storage, Transportation and Safety, IIT Bombay, Prof.Pratibha sharma

https://nptel.ac.in/courses/103101215

2. NOC : Electrochemical Energy Storage, IIT Kharagpur,Prof SubhasishBasu Majumdhar https://archive.nptel.ac.in/courses/113/105/113105102/

3. Energy Storage Technologies - From Chemistry to Engineering

https://www.udemy.com/course/energy-storage/

4. Introduction to battery-management systems, Gregory Plett

https://www.coursera.org/learn/battery-management-systems

5. Batteries, fuel cells, and their role in modern society, Dmitry Pelegov. Ural Federal University

https://learning.edx.org/course/course-v1:UrFUx+BATFUELC2017+1T2021

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Energy storage devices �Real-time application�

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� Real time Applications in day to day life and to Industry

1. Are Electric Vehicles India’s future?

https://youtu.be/7AneenfIDik?si=gPOA8Sai02nBMg1L

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2. What are the different types of hybrid vehicles?

https://youtu.be/Jh7YZfOH7gk?si=8QlqguReacVckd98

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3. The Battery Basics: Understanding Lithium-Ion, Lead-Acid And More

https://youtu.be/nrxmQhbZUTc?si=NctTm280Jv8iBOIu

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4. Toyota Prius lithium-ion and nickel metal hydride batteries and Toyota Mirai fuel cell hydrogen.

https://youtu.be/-yfPpIZYEjI

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5. How Do Electric Vehicles Work?

https://www.youtube.com/watch?v=GHGXy_sjbgQ

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6. Types of Electric Vehicles

https://www.youtube.com/watch?v=h5ysddrlXLw

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Self learning/Enrichment Topics

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1. Ni-Cad Battery

It is rechargeable secondary cell. It consists of cadmium anode and a highly oxidized nickel cathode that is usually described as the nickel(III) oxo-hydroxide, NiO(OH).

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Because the products of the discharge half-reactions are solids that adhere to the electrodes [Cd(OH)₂ and 2Ni(OH)₂], the overall reaction is readily reversed when the cell is recharged. Although NiCad cells are lightweight, rechargeable, and high capacity, they have certain disadvantages. For example, they tend to lose capacity quickly if not allowed to discharge fully before recharging, they do not store well for long periods when fully charged, and they present significant environmental and disposal problems because of the toxicity of cadmium.

Advantages:

• The Nickel-Cadmium cell has small size and high rate charge/discharge capacity, which makes it very useful.
• It has also very low internal resistance and wide temperature range (up to 70ºC)
• It produces a potential about 1.4 volt and has longer life than lead storage cell.

https://youtu.be/GMV_4U4wQfE

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Uses:

• These are used in electronic calculators, electronic flash units, transistors etc.
• Ni-Cd cells are widely used in medical instrumentation and in emergency lighting, toys etc.

Eco-friendly fuel cells in automobiles

Fuel cell vehicles use hydrogen gas to power an electric motor. Unlike conventional vehicles which run on gasoline or diesel, fuel cell cars and trucks combine hydrogen and oxygen to produce electricity, which runs a motor. Since they’re powered entirely by electricity, fuel cell vehicles are also considered as electric vehicles (“EVs”).

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1. Hydrogen gas from the tank feeds down a pipe to the positive terminal.
2. Oxygen from the air comes down a second pipe to the negative terminal.
3. The positive terminal is made of platinum. When hydrogen gas reach the catalyst, they split up into hydrogen ions and electrons.
4. The protons, being positively charged, are attracted to the negative terminal and travel through the electrolyte towards it. The electrolyte is a thin membrane made of a special polymer film and only the protons can pass through it.
5. The electrons, meanwhile, flow through the outer circuit.
6. As they do so, they power the electric motor that drives the car's wheels. Eventually, they arrive at the negative terminal too.
7. At the negative terminal, the protons and electrons recombine with oxygen from the air in a chemical reaction that produces water.
8. The water is given off from the exhaust pipe as water vapor or steam.

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Tesla's primary EV battery 

The technology involved is NCA (based on nickel-cobalt-aluminum oxide chemistry). Tesla’s new batteries will rely on innovations such as low-cobalt and cobalt-free battery chemistries, and the use of chemical additives, materials and coatings that will reduce internal stress and enable batteries to store more energy for longer periods.

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Lamborgini uses supercapacitor for its most powerful car

In the Sián, the supercapacitor provides enough power to the e-motor to deliver an extra 34 horsepower. Lamborghini uses this to smooth out acceleration, bridging the gaps in power delivery that occur when the mechanical transmission changes gear.

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Self learning/Enrichment Topics

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TYPES OF E-VEHICLES

The types of electric vehicle involves for various purpose are as follows

1.  Battery Electric Vehicles (BEVs): These are powered by 100% electric power. BEVs do not have an internal combustion engine and hence no fossil fuel is required. A typical travelling BEV can make a travel of 160 to 250 km, although some of them can travel as far as 500 km with just one charge. Currently Nissan Leaf, of 62 kWh battery provides an autonomy of 360 km.

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2. Plug-In Hybrid Electric Vehicles (PHEVs):

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The vehicles are propelled by both combustible engine and an electric engine charged by a pluggable external electric source. PHEVs can reduce the fuel consumption significantly by partly using electric charge. This will reduce the travel range challenge in BEVs. The Mitsubishi Outlander PHEV provides a 12 kWh battery, which allows it to drive around 50 km just with the electric engine.

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Hybrid Electric Vehicles (HEVs): The hybrid vehicles are propelled by a combination of a conventional internal combustion engine and an electric engine. The energy that powers the batteries are gained through regenerative braking or while driving using the combustion engine. The Toyota Prius, in its hybrid model (4th generation), provided a 1.3 kWh battery that theoretically allowed it an autonomy as far as 25 km in its all-electric mode.

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Fuel Cell Electric Vehicles (FCEVs): The vehicle are powered by hydrogen oxygen fuel cell. In this the chemical reaction occurs without combustion with product as water. These provides zero emissions. It is worth highlighting that, although there is green hydrogen, most of the used hydrogen is extracted from natural gas. The Hyundai Nexo FCEV [28] is uses fuel cell being able to travel 650 km without refuelling.

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Extended-range electric vehicles: (ER-EVs) vehicles are very similar to those ones in the BEV

category. However, the ER-EVs are additionally provided with a supplementary combustion

engine, which charges the batteries and not connected to the wheels of the vehicle. An example of this type of vehicles is the BMW i3, which has a 42.2 kWh battery that results in a 260 km autonomy in electric mode, and an additional 130 km is benefitted from the extended-range mode.

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Types of Batteries used in automobiles

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Lead-acid batteries (Pb-PbO2): It is the oldest kind of rechargeable battery. It is initially used as SLI (starting lighting and igniting) battery in automobiles. It has also been used in electric vehicles. It has very low specific energy and energy density ratios as shown in below figure. The battery is formed by lead grid pasted with leadsulphate as eletrodes flooded with sulfuric acid. During the initial loading process, the lead sulfate is reduced to Pb in the negative plates, while, in the positives, lead oxide is formed (PbO2).The sulphuric acid density is 1.2g/cc indicates the fully charged state. For example the GM EV1 and the Toyota RAV4 EV, are vehicles that used this kind of batteries.

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Nickel-cadmium batteries (Ni-Cd). This technology was used in the 90s, as these batteries have a greater energy density, but they present high memory effect, low lifespan, and cadmium is a very expensive and polluting element. Hence these are substituted by nickel-metal-hydride (NiMH) batteries.

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Nickel-metal-hydride batteries (Ni-MH): Negative electrode is made up of spongy nickel alloyed with metal hydride replacing cadmium. It shows high energy density. They show higher level of self discharge than Nicad, these batteries are used by many hybrid vehicles, such as the Toyota Prius, the second version of the GM EV1 and the Toyota RAV4 EV.

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Sodium sulfur batteries (Na-S): which contain sodium liquid (Na) and sulfur (S). It possess high energy density, high loading and unloading efficiency of 90%, and a long life cycle. The functioning temperatures is between 300 and 350^oC . It was used in the Ford Ecostar, the model that was launched in 1992–1993.

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Zinc-bromine batteries (Zn-Br2): In these types of batteries use zinc-bromine solution stored in two tanks, and in which bromide turns into bromine in the positive electrode. This technology was used by a prototype, called ”T-Star”, in 1993.

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Lithium-ion batteries (Li-Ion). In this battery intercalated lithium ion in carbon layer swings between negative plate to positive while discharging and positive to negative plate while charging. The advantages are light weight, low internal resistance, with high cycle life. They must operate within a safe and reliable operation area, restricted by the temperature (<130^oC)and voltage windows, violating may lead to firing of battery.

This type of battery is the most used today by the majority of EVs and PHEVs.

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Charging Modes

The international standard for charging electrical vehicles. Four modes to charge the vehicles.

Mode 1 (Slow charging): It is domestic charging mode, with a maximum intensity of 16 A, and it uses a either single-phase or three-phase power outlet with phase(s), neutral, and protective earth conductors.

Mode 2 (Semi-fast charging): It can be used at home or in public areas, it has maximum intensity of 32 A, and rest similar to the previous mode.

Mode 3 (Fast charging): It supply an intensity between 32 and 250 A. It requires the use of an EV Supply Equipment (EVSE), which provides communication with the vehicles, monitors the charging process, incorporates protection systems, and stops the energy flow when the connection to the vehicle is not detected.

Mode 4 (Ultra-fast charging): A direct connection of the EV to the DC supply network with a power intensity of up to 400 A and a maximum voltage of 1000 V, which provides a maximum charging power up to 400 kW.

Do it yourself

Cut open the primary alkaline (Duracell), Mobile batteries (wasted - Li ion batteries)

Analyse the components

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Mini project/ Activity�Unit - II

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Assessment Schedule

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Prescribed Text Books & Reference Books

• Textbooks
• P. C. Jain and Monika Jain, “Engineering Chemistry”, 17^th edition, Dhanpat Rai Publishing Company Pvt. Ltd., New Delhi, 2018.
• Prasanta Rath, “Engineering Chemistry”, Cengage Learning India Pvt. Ltd., Delhi, 2015.
• References
• S. S. Dara and S. S. Umare, “A Textbook of Engineering Chemistry”, S. Chand & Company, New Delhi, 2015.
• Kirpal Singh, “Chemistry in everyday life”, 3^rd edition, -PHI Learning Pvt. Ltd., 2012.
• J.C. Kuriacose and J.Rajaram, “Chemistry in Engineering and Technology”, Volume-1 & Volume -2, Tata McGraw-Hill Education Pvt. Ltd., 2001.
• Geoffrey A Ozin, Andre C Arsenault “Nanochemistry: A Chemical Approach to Nanomaterials”, 2^nd edition, RSC publishers, 2005.
• Prasanna Chandrasekhar, “Conducting polymers, fundamentals and applications A Practical Approach”, 1^st edition, Springer Science Business Media New York, 1999.

E-Content:

Engineering Chemistry - Fundamentals and Applications - Shikha Agarwal

https://www.pdfdrive.com/engineering-chemistry-fundamentals-and-applications-2nd-edition-d191456798.html

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