Microteaching in PPT-Topic batterie.pptx

Battery concept basics for studying material

1. Electrochemical Device: Battery (24CT101) By Dr. Y S L V Narayana Assistant Professor Department of Chemistry VFSTR, Vadlamudi

2. The interrelationship of ΔG°, E°cell, and K For a spontaneous redox reaction, Δ G < and E cell > 0. Δ G = - nFE cell n = mol of e - transferred F is the Faraday constant = 9.65x10 4 J/V·mol e - Under standard conditions, Δ G° = - nFE° cell and E ° cell nF = RT ln K or E ° cell = 0.0592 V log K n for T = 298.15 K

3. A. Any one of these thermodynamic parameters can be used to find the other two. B. The signs of G o and E o cell determine the reaction direction at standard-state conditions.

4. 4 Relating free energy and cell potential The Faraday: F = 96 485 C/mole Standard conditions (1 M, 1 atm , 25 °C) Free energy is extensive property so need to multiply by no of moles involved. But to convert to E we need to divide by no of electrons involved. E is an intensive property.

5. 5 The Nernst equation Working in nonstandard conditions

6. 6 Contents of topic Definition and Applications of Batteries Classification of Batteries Battery characteristics Construction and working and applications of lead-acid storage cell Lithium-ion battery Fuel cells-Classification Construction, working and applications H2-O2 fuel cell and solid oxide fuel cell Concept of Redox-flow batteries

7. Batteries (Electrochemical Cells)

8. Contents What is battery Components in battery Role of each component in battery Types of batteries Applications of batteries How a battery works

9. Batteries The cell is a single unit, so it is light and compact, whereas the battery is a collection of cells .  A container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power

10. Cell vs Battery

11. Components in Battery A battery, also known as a cell, is made up of three parts:  a cathode, an anode, and an electrolyte . Within the cell, a chemical process occurs, transferring electrons from one location to another and creating an electric current. Electrolyte and an anode are found in half of the cell An electrode is  a solid electric conductor that carries electric current In an electrochemical cell, reduction and oxidation reactions take place at the electrodes. The cathode is the positive electrode, where reduction (gain of electrons) occurs, while the anode is the negative electrode, where oxidation (loss of electrons) takes place. An electrolyte is  the battery component that transfers ions — charge-carrying particles — back and forth between the battery's two electrodes, causing the battery to charge and discharge

12. Basic structure of Battery

13. How a Battery Works A battery is a device that stores chemical energy and converts it to electrical energy. The chemical reactions in a battery involve the flow of electrons from one material (electrode) to another, through an external circuit.  The flow of electrons provides an electric current that can be used to do work To balance the flow of electrons, charged ions also flow through an electrolyte solution that is in contact with both electrodes Different electrodes and electrolytes produce different chemical reactions that affect how the battery works, how much energy it can store and its voltage. 

14. Classification of Batteries Primary batteries Secondary batteries Batteries were classified mainly as two types based on properties Primary batteries are “single use” and cannot be recharged. Dry cells and (most) alkaline batteries are examples of primary batteries. The second type is rechargeable and is called a secondary battery. Examples of secondary batteries include nickel-cadmium (NiCd), lead acid, and lithium-ion batteries Primary batteries Secondary batteries

15. Primary Cell Construction of Dry Cell: The Zinc vessel serves as anode. The cathode is a graphite rod in the center of the cell. Graphite rod is surrounded by the electrolyte which consists of a paste of NH 4 Cl, ZnCl 2 , MnO 2 and traces of acetylene black, graphite powder . Starch is added to make the mixture like a thick paste.

16. Primary Cell (Dry Cell) Cell representation of Dry Cell: Cell reactions involved: + Primary Cell

17. Primary Cell (Dry Cell) Cell reactions involved: The liberated NH 3 , reacts with Zn 2+ ions to form a complex [Zn(NH 3 ) 2 Cl 2 ] The cell is a primary cell and gives a voltage of 1.5 V. Gradually, the voltage drops due to anodic and cathodic reactions. Advantages: These cells are used in transistors, tape recorders, toys, portable electronic devices.

18. Primary Cell (Dry Cell) Disadvantages: These cells do not have long life because the acidic NH 4 Cl corrodes the container even when the cell is not in use. When the current is rapidly drawn from the cell, voltage drop takes place due to the building up of products at the electrodes.

19. Lead-acid Battery

20. Cell representation: Cell reactions involved: Lead-acid Battery