That would depend on the type of battery, and probably also on the ambient temperature.
what type of energy is stored in batteries
You should never store batteries in equipment for too long a period as they may leak and destroy the equipment they are powering. This is especially true if the environment they are stored is hot and humid. In a cooler, drier area they might last a bit longer.
electricity is stored in batteries
Batteries are stored energy devices.
Chemically
Batteries are a good example.
it is the energy stored in batteries
Electrical energy can be stored in batteries. Water energy can be stored behind dams.
it is the energy stored in batteries
Yes that's what batteries do.
Chemical Energy.
chemical energy