(Invited) Important Factors Affecting Calendar Life of Lithium Metal Batteries

With the growing maturity of lithium (Li) ion battery technologies, Li metal battery (LMB) is being revitalized in recent years to achieve high energy density. Great progress has been made in understanding the Li utilization and extending the cycle life of LMBs. However, the study of calendar life of LMBs is still limited, although the calendar life of the battery is also critical for application of LMBs. Therefore, there is an urgent need to investigate the calendar life of LMBs systematically and extend their calendar life. In this work, we will report our recent works on investigation of the calendar life of LMBs based on Li||NMC811 cells using advanced localized high concentration electrolyte, which has already demonstrated excellent cycling stability. Two key criteria, self-discharge rate (percentage of capacity loss per day at open circuit) and recoverable capacity after long-term storage, are used to quantify the calendar aging at different states of charge (SOCs) and temperatures. Together with the postern mortem analysis of Li metal anode and NMC811 cathode retrieved from the long-term stored cells, this work provided an in depth understanding on the important factors affecting calendar aging of LMBs. These findings can guide the storage of LMBs and shed light on the further development of LMBs. Figure 1