Effects of low-temperature pre-cycling on high-temperature cycle life of lithium-ion cells

Here we report an interesting phenomenon that lithium plating from pre-cycling of Li-ion cells at low temperature could reduce degradation and extend cycle life at high temperature. This study confirmed the phenomenon in both single-layer cells and multi-layer cells. It revealed that compression of the multi-layer cells must be maintained during cycling for the phenomenon to be observed. Without compression, low-temperature pre-cycling would accelerate high-temperature degradation of the multi-layer cells. This finding helped to clarify the contradictions in previous studies on the effects of low-temperature pre-cycling. A comparison between low-temperature pre-cycling with 1C charging and 0.2C charging confirmed that lithium plating from low-temperature pre-cycling is necessary for the observed benefits. Furthermore, post-mortem analysis of single-layer cells showed a thick deposition layer on the anode of pre-cycled cells, which could be attributed to reactions from lithium plating and the electrolyte.