Understanding and quantifying capacity loss in storage aging of Ah-level Li metal pouch cells

Promoting industry applications of high-energy Li metal batteries (LMBs) is of vital importance for accelerating the electrification and decarbonization of our society. Unfortunately, the time-dependent storage aging of Ah-level Li metal pouch cells, a ubiquitous but crucial practical indicator, has not yet been revealed. Herein, we first report the storage behaviors and multilateral synergistic aging mechanism of Ah-level NCM811||Li pouch cells during the 120-day long-term storage under various conditions. Contrary to the conventional belief of Li-ion batteries with graphite intercalation anodes, the significant available capacity loss of 32.8% on average originates from the major electrolyte-sensitive anode corrosion and partial superimposed cathode degradation, and the irreversible capacity loss of 13.3% is essentially attributed to the unrecoverable interface/structure deterioration of NCM with further hindrance of the aged Li. Moreover, principles of alleviating aging have been proposed. This work bridges academia and industry and enriches the fundamental epistemology of storage aging of LMBs, shedding light on realistic applications of high-energy batteries. (Figure presented.).