In-Situ Detection of Lithium Plating Using High Precision Coulometry

Plating of metallic lithium on the negative electrode in lithium-ion batteries can dramatically reduce cell lifetime, impact cell safety and must be avoided during normal cell operation. Due to the low efficiency of the lithium plating/stripping process relative to the intercalation/deintercalation of lithium from graphite, small amounts of lithium plating can be detected through high accuracy measurements of coulombic efficiency. In this study, coulombic efficiency versus charging rate was measured at different temperatures and for two cell types. Small changes to the coulombic efficiency during cycling resulting from small amounts of lithium plating during the charging process were detected using a high precision charger. Cells were disassembled and examined to confirm the presence of lithium plating at the rates predicted to cause plating. This work shows how high precision coulometry can be used to maximize the performance of the cell through battery management by varying the maximum charge rate as a function of temperature to avoid lithium plating.