The capacity of all three groups of Li-ion batteries decayed by more than 20%, and when the SOH of Li-ion batteries was below 80%, they reached the standard of retired batteries.
The degradation mechanism of lithium-ion batteries is complex and the main cause of performance degradation of lithium-ion batteries at low temperatures is lithium plating. During charging, lithium ions migrate from the cathode to the anode and become entrapped in the graphite layer.
Cycling degradation in lithium-ion batteries refers to the progressive deterioration in performance that occurs as the battery undergoes repeated charge and discharge cycles during its operational life . With each cycle, various physical and chemical processes contribute to the gradual degradation of the battery components .
Lithium-ion batteries unavoidably degrade over time, beginning from the very first charge and continuing thereafter. However, while lithium-ion battery degradation is unavoidable, it is not unalterable. Rather, the rate at which lithium-ion batteries degrade during each cycle can vary significantly depending on the operating conditions.
Stress One of the main factors contributing to lithium-ion battery degradation is mechanical stress at the anode . There is a number of negative consequences that might arise from mechanical stress on the anode.
Consumption of the cell’s lithium ions through SEI growth is one contributing factor to the degradation mode known as loss of lithium inventory (LLI). Because these reactions occur even when the cell is not in use, known as calendar aging, lithium-ion battery degradation is unavoidable.