Introduction:
When two or more cells are joined together, they form a battery. A battery is a device that converts chemical energy into electrical energy to power various electronic devices.

Explanation:
When cells are connected together, their individual voltages add up, resulting in a higher voltage output. This allows the battery to provide a steady and reliable source of electrical energy.

Types of Batteries:
There are different types of batteries available, such as:

1. Primary Batteries: These batteries are disposable and cannot be recharged. They are commonly used in devices like remote controls, flashlights, and toys.

2. Secondary Batteries: Also known as rechargeable batteries, these batteries can be recharged multiple times. They are commonly used in laptops, smartphones, and electric vehicles.

Structure of a Battery:
A typical battery consists of the following components:

1. Positive Electrode (Cathode): It is the terminal of the battery where electrons flow out during discharge.

2. Negative Electrode (Anode): It is the terminal of the battery where electrons flow in during discharge.

3. Electrolyte: It is a chemical medium that allows the flow of ions between the positive and negative electrodes.

4. Separator: It is a material that prevents direct contact between the positive and negative electrodes, while allowing the flow of ions.

5. Container: It holds all the components of the battery together and provides protection.

6. Terminals: These are the external connections of the battery that allow it to be connected to an electronic device.

Working of a Battery:
When a battery is connected to a circuit, a chemical reaction occurs within the battery. This reaction causes a flow of electrons from the negative electrode to the positive electrode through the external circuit, creating an electrical current. Simultaneously, positive ions flow through the electrolyte from the negative electrode to the positive electrode to balance the flow of electrons.

Conclusion:
In conclusion, when two or more cells are joined together, they form a battery. A battery is a device that converts chemical energy into electrical energy. It consists of a positive electrode, negative electrode, electrolyte, separator, container, and terminals. By connecting a battery to a circuit, it provides a steady source of electrical energy to power various electronic devices.