From：CTECHI GROUP Limited Release time：2020-07-01
Overview：After the lithium battery has been used for a certain period of time, the battery can be used continuously for a shorter period of time. In fact, this is caused by the loss of capacity of the lithium battery. What is the reason for the loss of lithium battery capacity?
After the lithium battery has been used for a certain period of time, the battery can be used continuously for a shorter period of time. In fact, this is caused by the loss of capacity of the lithium battery. What is the reason for the loss of lithium battery capacity?
(1) The deposited lithium is coated on the surface of the negative electrode, blocking the intercalation of lithium, and the amount of recyclable lithium is reduced, resulting in a decrease in discharge efficiency and a loss in capacity.
(2) Metallic lithium is usually formed between the negative electrode and the separator, which may block the pores of the separator to increase the internal resistance of the battery. Fast charging, current density is too large, the negative electrode is heavily polarized, and lithium deposition is more pronounced.
(3) The generation of electrochemically inert substances destroys the capacity balance between the electrodes, resulting in capacity loss, and the capacity loss is irreversible.
(4) Self-discharge. Self-discharge refers to the phenomenon that the battery naturally loses its capacity when it is not in use. Lithium-ion battery self-discharge leads to capacity loss in two cases: one is reversible capacity loss; the other is irreversible capacity loss. Reversible capacity loss means that the lost capacity can be recovered during charging, while the irreversible capacity loss is reversed. The positive electrode and the solvent may act as micro-cells to generate self-discharge resulting in irreversible capacity loss.
(5) Electrode instability. When the positive electrode active material is in a charged state, the oxidizing electrolyte is decomposed to cause a capacity loss. In addition, factors affecting the dissolution of the positive electrode material are structural defects of the positive electrode active material, a high charging potential, and a carbon black content in the positive electrode material. The structural change of the electrode during the charge and discharge cycle is the most important factor.