Reasons for the capacity decline of ternary lithium-ion (NCM) batteries

　　For traditional batteries, ternary lithium-ion (NCM) batteries have the advantages of long life, energy saving, environmental protection, no pollution, low maintenance costs, complete charge and discharge, and light weight.

　　In theory, the NCM lithium battery has a cycle life of 500-1000 cycles, but in the actual application process, it is far from reaching its theoretical life. So, what causes the capacity decline of the ternary lithium battery?

　　The lifespan of lithium-ion batteries largely depends on the stability of their charge-discharge cycles. Like other secondary batteries, the capacity degradation of lithium batteries during cycling is inevitable.

　　High-rate charging and discharging will also cause capacity loss of NCM lithium batteries. This is because the positive and negative electrodes will shrink and expand in volume during the charging and discharging process. The greater the charge and discharge current, the more severe the contraction and expansion, and the greater the stress, which is positive and negative. Extreme particles are more likely to rupture or peel off from the current collector during rapid changes in volume, resulting in faster cycle decay.

　　Too high temperature or too low temperature will cause the reduction of active lithium-ion content, thereby reducing the life of lithium battery. Temperature is definitely one of the key factors affecting the life of lithium batteries.

　　The essence that affects the capacity degradation of ternary lithium batteries is the decrease in the content of lithium ions that can be unembedded. The main factors are the decomposition of the electrolyte, the structural damage or deactivation of the positive and negative materials, and the abuse of lithium batteries.

　　The charging and discharging process of the battery is a complex electrochemical process, and the factors that cause the battery capacity attenuation are not single, and the deterioration of one aspect may cause other factors to jointly affect the battery capacity, cycle performance, energy density, etc.