A battery refers to a portion of a cup, trough or other container or composite container containing an electrolyte solution and a metal electrode to generate electrical current. As technology advances, batteries are broadly referred to as small devices that generate electrical energy. Such as solar cells. The performance parameters of the battery mainly include electromotive force, capacity, specific energy and resistance. (1) Open circuit voltage of the battery (2) Internal resistance of the battery (3) Operating voltage of the battery (4) Charging voltage The charging voltage refers to the voltage applied to the two ends of the battery when the secondary battery is being charged. The basic methods of charging are constant current charging and constant voltage charging. Constant current charging is generally used, which is characterized by constant charging current during charging. As the charging progresses, the active material is recovered, the electrode reaction area is continuously reduced, and the polarization of the motor is gradually increased. (5) Battery capacity Battery capacity refers to the amount of electricity that is obtained from the battery. It is usually expressed by C, and the unit is usually expressed by Ah or mAh. Capacity is an important indicator of battery electrical performance. The capacity of a battery is usually divided into theoretical capacity, actual capacity, and rated capacity.The battery capacity is determined by the capacity of the electrodes. If the capacity of the electrodes is not equal, the capacity of the battery depends on the electrode with a small capacity, but it is never the sum of the positive and negative electrodes. (6) Battery storage performance and life One of the main features of a chemical power source is the ability to discharge electrical energy when in use and to store electrical energy when not in use. The storage performance is a charge retention capability for a secondary battery. For secondary batteries, an important parameter to measure battery performance over the life of the battery. The secondary battery is charged and discharged once, and is called a cycle (or one cycle). Under a certain charge and discharge system, the number of charge and discharge cycles that the battery can withstand before the battery capacity reaches a certain value is called the use cycle of the secondary battery.