What is the basic principle of lithium-ion battery charging and discharging?

　　We must first clarify two concepts:

　　1. The battery is a device that converts the chemical energy of the oxidation-reduction reaction into electrical energy. The typical feature is that the reactants on the electrode gain and lose electrons, which flow through the external circuit, and then generate an electric current. The charge transfer between the positive and negative electrodes is formed by the movement of anions and cations in the electrolyte.

　　2. The secondary battery refers to a battery that can be recharged and discharged multiple times, and the electrochemical reaction that occurs inside it is reversible. When the battery is discharged, the internal substance A becomes substance B, and the chemical energy becomes electric energy; while charging, the substance B can be changed back to substance A, and the electric energy becomes chemical energy storage.

　　After clarifying the basic concepts, let's look at the specific chemical reactions of lithium-ion batteries.

　　During charging, lithium ions are extracted from the crystal lattice of the positive electrode material and inserted into the negative electrode material layer through the electrolyte.

　　Lithium ions are extracted from the crystal lattice of the negative electrode material during discharge, and are inserted into the positive electrode material through the electrolyte.

　　Electrons pass through an external circuit to form an electric current.

　　The charging and discharging reaction process of lithium battery is:

　　In the above formula, Y is a transition metal. For ternary lithium batteries, it is NiCoMn in lithium nickel cobalt manganese oxide [Li(NiCoMn)O2], and for lithium iron phosphate (LiFePO4) batteries, it is FePO4.

　　In addition, the difference between the positive electrode and the negative electrode refers to the level of the voltage level, the higher one is the positive electrode, and the lower one is the negative electrode.

　　The cathode and the anode should be distinguished by the gain and loss of electrons. The reduction reaction that obtains electrons is the cathode, and the oxidation reaction that loses the electrons is the anode.

　　When charging and discharging, the positive and negative electrodes are unchanged, but the cathode and anode will be reversed.

　　The above is the basic principle of charging and discharging lithium-ion batteries.

　　Lithium-ion battery (LIB) has become the main energy storage solution in modern social life. Among them, lithium iron phosphate batteries are a perfect substitute for lead-acid batteries and are the first choice in the energy storage industry.