A battery is basically a mini-power plant, converting a chemical reaction into electrical energy. Dry cell (alkaline) batteries can differ in several ways, but they all have the same basic components.
A steel casing that houses the cathode components.
This is a mixture of manganese dioxide and carbon. Cathodes are the electrodes that are reduced by the electrochemical reaction.
The separator is a non-woven, fibrous fabric that keeps the electrodes apart.
A powdered zinc metal. Whilst the cathodes are reduced, the anodes are the electrodes that are oxidised in the reaction.
These are where the electrochemical reaction takes place.
This is a potassium hydroxide solution in water and acts as the medium for the movement of ions within the cell. It also carries the ionic current inside the battery.
A simple brass pin in the middle of the cell that conducts electricity to the outer circuit.