Regulating the lithium metal growth by Li3BO3/Li2OHCl solid-state electrolyte for long-lasting lithium metal stripping-plating

Lithium-rich anti-perovskite materials, with their high theoretical Li+ conductivity and relatively low energy barrier for Li+ transport, are highly promising as an electrolyte contender in all-solid-state lithium-metal batteries. Their current performance is however compromised by the grain boundary to result in low Li+ conductivity and high activation energy. Herein, a composite electrolyte is prepared by introducing the glassy Li3BO3 into the Li2OHCl to serve as a bridge to connect the Li2OHCl grains together to lower the impact from the grain boundary. The Li + conductivity of Li2OHCl can be improved by the presence of 10 wt% Li3BO3, and its impact on the lithium metal growth behavior is also investigated. It is found that the lithium-metal battery with Li3BO3/Li2OHCl prefers the deposition of lithium metal particles with larger size than that in the battery with Li2OHCl. Consequently, the lithium-metal symmetric cell with 10 wt% Li3BO3/Li2OHCl is able to display excellent cycling for over 1800 h at 0.1 mA cm−2. The batteries with 10 wt% Li3BO3/Li2OHCl are also able to improve the cycle stability and rate performance. The results of this study provide the direct experimental proof of the effect of grain boundary in Li2OHCl on the battery performance.