Impacts of lean electrolyte on cycle life for rechargeable Li metal batteries

Strong demand for higher energy batteries for extended range electric vehicles has driven battery technology development toward Li metal batteries. One limitation of Li metal batteries is cycle life. At odds are the amount of electrolyte to fulfill high energy and the amount needed to achieve long cycle life. Here we employ an electrochemical model and design of experiment to understand impacts on cycle life and failure as electrolyte content is reduced to levels needed to achieve reasonably high specific energy. With lean electrolyte, a gap exists in achieving long cycle life with a reduction by a factor of 6.5 when electrolyte amount is reduced from 37.0 g Ah−1 to 6.0 g Ah−1. Two primary failure routes are identified with differences between lean and high electrolyte quantities. The results suggest that reporting and performing experiments for high energy cell designs requires that amount of electrolyte be considered a critical parameter. •High specific energy rechargeable Li metal batteries require limited electrolyte.•Lean electrolyte changes failure mode.•Lean electrolyte increases variability.•Appropriate conditions need to be used for experimental design.