Primary and secondary batteries, fuel cells

1. Introduction to Batteries

1. A battery is an electrochemical device that converts chemical energy into electrical energy.
2. Batteries are classified as primary (non-rechargeable) or secondary (rechargeable).
3. They consist of two electrodes (anode and cathode) and an electrolyte for ionic conduction.

2. Primary Batteries

1. Primary batteries are designed for single-use and cannot be recharged.
2. Examples include:
   • Dry cell: Used in flashlights, remote controls, and toys.
   • Alkaline battery: Provides a longer lifespan than dry cells.
3. Advantages:
   • Low cost and easy availability.
   • Suitable for portable devices.
4. Disadvantages:
   • Non-rechargeable; contributes to electronic waste.

3. Secondary Batteries

1. Secondary batteries can be recharged and used multiple times.
2. Examples include:
   • Lead-acid battery: Used in automobiles and inverters.
   • Nickel-Cadmium (Ni-Cd) battery: Used in emergency lighting and portable electronics.
   • Lithium-ion (Li-ion) battery: Widely used in smartphones, laptops, and electric vehicles.
3. Advantages:
   • Rechargeable and cost-effective over time.
   • High energy density in modern batteries like Li-ion.
4. Disadvantages:
   • Higher initial cost.
   • Requires proper disposal to prevent environmental harm.

4. Fuel Cells

1. Fuel cells are electrochemical cells that convert the chemical energy of a fuel (e.g., hydrogen) directly into electrical energy.
2. Components include:
   • Anode: Oxidation of the fuel occurs.
   • Cathode: Reduction of oxygen occurs.
   • Electrolyte: Conducts ions between electrodes.
3. Common types:
   • Proton Exchange Membrane (PEM) Fuel Cell: Used in vehicles and portable devices.
   • Solid Oxide Fuel Cell (SOFC): Operates at high temperatures, suitable for power generation.
4. Advantages:
   • High efficiency compared to traditional combustion methods.
   • Environmentally friendly when using clean fuels like hydrogen.
5. Disadvantages:
   • High initial cost and complex infrastructure requirements.

5. Key Points for Competitive Exams

1. Batteries are categorized as primary (single-use) and secondary (rechargeable).
2. Lead-acid batteries are commonly used in automobiles, while Lithium-ion batteries dominate portable electronics.
3. Fuel cells offer a clean and efficient energy source but require high investment.
4. Faraday's laws apply to battery operation, governing the relationship between current and chemical reactions.
5. The Lithium-ion battery is preferred for electric vehicles due to its high energy density and long lifespan.
6. Hydrogen fuel cells are promising for renewable energy but face challenges in fuel storage and distribution.
7. Alkaline batteries are commonly used in household appliances due to their reliability.