Rate-Dependent Failure Mechanisms and Mitigating Strategies of Anode-Free Lithium Metal Batteries

Anode-free lithium (Li) metal batteries (AFLMBs) could provide a specific energy over 500 Wh/kg, but their cycle life requires improvement. In this work, we propose a new method to calculate the real Coulombic efficiency (CE) of the Li metal during the cycling of AFLMBs. Through this approach, we find low rate discharging unfavorable for Li CE, which is mitigated through electrolyte optimization. In contrast, high rate discharging boosts Li reversibility, indicating AFLMBs to be intrinsically suited for high power use cases. However, AFLMBs still fail rapidly, due to the Li stripping overpotential buildup, which is mitigated by a zinc coating that enables a better electron/ion transferring network. We believe well-targeted strategies need to be better developed to synergize with the intrinsic features of AFLMBs to enable their commercialization in the future.