Understanding how chemical energy transforms into electrical energy using redox reactions.
What Is a Battery?
Batteries are electrochemical devices that convert chemical energy into electrical energy. This is achieved through redox (reduction-oxidation) reactions involving the transfer of electrons between two electrodes.
Basic Components of a Battery
| Component | Function |
|---|---|
| Anode | Undergoes oxidation (loses electrons) |
| Cathode | Undergoes reduction (gains electrons) |
| Electrolyte | Allows ion flow between electrodes |
| Separator | Prevents contact between anode and cathode |
1. Primary Batteries (Single-use)
These are non-rechargeable batteries. Once the chemical reactions are complete, they cannot be reversed.
- Dry Cell: Zinc (anode), MnO₂ (cathode), NH₄Cl paste (electrolyte)
- Alkaline Battery: Uses KOH electrolyte; longer life than dry cells
Applications: Remote controls, toys, flashlights
2. Secondary Batteries (Rechargeable)
These batteries allow the reversal of chemical reactions through charging.
- Lead-Acid Battery: Common in cars. Uses lead and lead dioxide in sulfuric acid.
- Nickel-Cadmium (Ni-Cd): Rechargeable, long life, but environmentally hazardous.
- Lithium-Ion: High energy density; used in smartphones, laptops, and EVs.
Applications: Electric vehicles, mobile devices, UPS systems
3. Fuel Cells
Fuel cells generate electricity through the continuous supply of fuel (typically hydrogen) and oxygen.
Reaction: H₂ + O₂ → H₂O + Electricity
Applications: Spacecraft, hydrogen-powered vehicles, power backups
How Does a Battery Work?
- Oxidation occurs at the anode, releasing electrons.
- Electrons flow through the external circuit, generating electric current.
- Reduction occurs at the cathode, where electrons are accepted.
- Ions in the electrolyte flow to maintain charge balance.
Key Electrochemistry Terms
- Voltage (V): The potential difference between two electrodes
- Capacity (mAh): How much charge the battery can store
- Cycle Life: Number of complete charge-discharge cycles before degradation
The Future of Battery Technology
- Solid-state Batteries: Safer, more compact, longer life
- Graphene Batteries: Extremely fast charging and high capacity
- Sodium-ion Batteries: Low-cost alternative to lithium-ion batteries
Summary: Battery Types at a Glance
| Type | Rechargeable | Energy Density | Common Uses |
|---|---|---|---|
| Primary Battery | ❌ No | Moderate | Remotes, clocks |
| Secondary Battery | ✅ Yes | High | Mobiles, EVs |
| Fuel Cell | ✅ Yes | Very High | EVs, backup power |
Batteries are the powerful bridge between chemistry and the digital world.
