Lithium batteries commonly experience self-discharge. What is self-discharge? Simply put, it refers to the phenomenon where a battery with a certain initial charge gradually loses its stored electrical energy after being left in an open-circuit state for a period of time, due to various internal factors. A battery’s ability to retain its charge in this state is known as charge retention capability, and the self-discharge rate is usually expressed as the ratio of remaining capacity to initial capacity.
The causes of self-discharge can be understood through the battery’s own inherent characteristics. Even when a battery is not connected to any external load, two main types of processes may still occur internally: first, irreversible side reactions between electrode materials and the electrolyte lead to a loss of active materials—this part of the loss is permanent, reduces the battery’s total capacity, and cannot be restored through recharging; second, tiny local short circuits or leakage within the battery create micro-current paths that directly consume charge, but this loss is physically reversible and does not cause permanent capacity decay.
Typical self-discharge rates for different battery types