A secondary battery, often called a rechargeable battery, works by converting chemical energy into electrical energy through a reversible electrochemical reaction. This allows the battery to be repeatedly used, discharged, and restored to its initial charged state.
The Basic Mechanism of a Secondary Battery
Here's a simplified breakdown of how a secondary battery functions:
- Discharge:
- When a device is powered, the battery undergoes a chemical reaction that releases electrons.
- These electrons flow through an external circuit, providing electrical power.
- This process converts chemical energy into electrical energy.
- Charging:
- The battery is recharged by applying an external electrical current.
- This forces the chemical reaction to reverse, storing energy back into the battery.
- The process restores the battery to its original charged condition.
- Reversible Process: The key characteristic of a secondary battery is this reversibility of the chemical reaction, allowing for multiple charge and discharge cycles.
Key Differences from Primary Batteries
Unlike primary batteries, which are designed for single use and cannot be recharged, secondary batteries can be used many times because their chemical processes are reversible.
| Feature | Secondary Battery (Rechargeable) | Primary Battery (Non-Rechargeable) |
|---|---|---|
| Rechargeable | Yes | No |
| Use | Multiple Uses | Single Use |
| Chemical Process | Reversible | Irreversible |
Practical Applications of Secondary Batteries
Secondary batteries are ubiquitous in our modern lives:
- Portable Devices: They power personal digital assistants, mobile telephones, and notebook computers.
- Automotive: They are used to start vehicles and power electric cars.
- Power Tools: They provide power for various cordless tools.
- Energy Storage: They are increasingly used in grid-scale energy storage to integrate renewable energy sources.
Charging Process Explained
Charging a secondary battery involves reversing the current flow. Here's what happens:
- External Source: An external power source is used, like an outlet or charger.
- Reversed Flow: The charger forces electrical current into the battery, reversing the direction of electron flow during discharge.
- Chemical Restoration: This current forces the chemicals in the battery to return to their charged state.
- Energy Storage: The chemical energy is now stored in the battery and ready to be used again.
As described by the provided reference, "Secondary batteries, often called rechargeable batteries, can be used, discharged, and then restored to their original condition by reversing the current flow (charging)."
