(1) The process of charging
The process of charging a capacitor (storing charge and electrical energy) is called charging. Connect one electrode of the capacitor to the positive pole of the power supply and the other electrode to the negative pole of the power supply, and the two electrodes will each carry an equal amount of dissimilar charges. After charging, there is an electric field between the two plates of the capacitor, and the charging process stores the electrical energy obtained from the power source in the capacitor.
(2) The process of discharge
The process of causing a charged capacitor to lose charge (releasing charge and electrical energy) is called discharge. For example, by connecting the two poles of a capacitor with a wire, the charges on both poles will neutralize each other, and the capacitor will release both charges and electrical energy. After discharge, the electric field between the two plates of the capacitor disappears, and the electrical energy is converted into other forms of energy.
Battery self discharge refers to the ability of a battery to retain stored charge in an open circuit state. The self discharge types of lithium-ion batteries can be divided into physical self discharge and chemical self discharge. Battery cells are assembled into modules through series and parallel connections. If the self discharge consistency of the cells in the module is poor, it can lead to inconsistent internal cell terminal voltages after storage for a period of time. This can result in some cells reaching the target voltage while others remain at higher or lower voltages during the charging and discharging process, leading to overcharging or overdischarging of the cells and even safety issues. This is also a challenge to the voltage balancing ability of the module. Self discharge is an important performance indicator of lithium-ion capacitors.
