Coulombic Efficiency of Lithium Deposition and Stripping on Lithium Metal: A New Method for Measuring

Abstract Rechargeable lithium metal batteries (RLMBs) have been extensively investigated as a next‐generation battery for electric vehicles because of their two times higher specific energy density than conventional lithium‐ion batteries. However, RLMBs have not been commercialized yet, because of the low coulombic efficiency (CE) of the lithium deposition and stripping process and lithium dendrite formation. CEs measured by a conventional method with a Li/electrolyte/Cu were considerably lower than those measured using full cells of Li/electrolyte/oxide cathode. The discrepancy is considered to be due to the non‐reversibility of the Cu electrode for the lithium deposition and stripping process. Here, we propose a new method to determine the CE of lithium deposition and stripping on lithium metal from the loss of electrolyte using a Li/electrolyte/Li cell with a limited amount of electrolyte.