What type of energy is stored in a battery?

A battery stores potential energy. This form of energy is associated with the position of charged particles within the battery. When a battery is charged, chemical energy is converted and stored as potential energy due to the separation of positive and negative charges.

When the battery is connected in a circuit, this potential energy is transformed into electrical energy, which can then be used to power devices. The key aspect of potential energy in this context is that it is energy that has the potential to be converted into another form of energy (in this case, electrical energy) when the conditions allow it, such as during discharge.

Kinetic energy relates to the energy of motion, which does not apply to the energy stored in a battery. Mechanical energy encompasses both kinetic and potential energy in a mechanical system but is not specific to the stored energy in a battery. Thermal energy pertains to the energy related to the temperature of a system, which is not the primary function of a battery's energy storage. Therefore, potential energy is the correct and most relevant term to describe the energy stored in a battery.