Final answer:
A battery stores chemical potential energy, which is a form of potential energy that can be transformed into electrical energy when the battery is used.
Step-by-step explanation:
The type of energy stored inside a battery is chemical potential energy. This energy is a form of potential energy which the battery contains and can release in the form of electrical energy through a chemical reaction. The chemical reaction within the battery drives electrons through a circuit, converting the stored chemical potential energy into electrical energy, which can then be transformed into other forms of energy such as light and heat in various devices. When a battery is in use, its capacity to do work on charge to move it around a closed circuit represents its potential energy, which decreases over time as the chemical reactants are used up.