I’m looking for a shorter answer too. Like 1-2 paragraphs. Freshman level.
A battery is a device that stores chemical energy and converts it to electrical energy.
The chemical reactions in a battery involve the flow of electrons from one material (electrode) to another, through an external circuit.
The flow of electrons provides an electric current that can be used to do work.
To balance the flow of electrons, charged ions also flow through an electrolyte solution that is in contact with both electrodes.
Different electrodes and electrolytes produce different chemical reactions that affect how the battery works, how much energy it can store and its voltage.