Lithium Battery Cycle Life and Capacity Fade

The service life of lithium batteries is usually measured by the number of charge-discharge cycles and years of use. Consumer-grade lithium-ion batteries have a service life of approximately 3-5 years and a cycle life of about 500-1000 cycles. When the number of cycles reaches its upper limit, the effective capacity of the battery will drop to less than 70% of its initial capacity. The main mechanisms of capacity fade include: structural changes in positive and negative electrode materials that reduce the deintercalation efficiency of active substances, thickening of the SEI film that increases electronic impedance, and electrolyte decomposition and lithium dendrite formation, which may cause internal short circuits. Studies have shown that if a full charge-discharge cycle is performed every day, the capacity fade will become relatively obvious after about 1.5-3 years.