Answer:
The energy conversion does not fully occur due to various energy losses.
Explanation:
There are many different types of batteries, but all have three basic components: positive electrode (cathode, or "positive terminal"), negative electrode (anode or "negative terminal"), and electrolyte.
Charging a battery forces ions from cathode to anode; the battery reverses the flow. Over a period of time, this process wears out cathode, which results in reduced capacity.
Also there can be heat loss inside the system as well which is produced by the conversion from chemical energy.
Hence the chemical energy does not fully convert to electrical energy.