Preventing lithium plating under extremes: an untold tale of two electrodes

Fast charging of lithium-ion cells is key to alleviate range anxiety and improve the commercial viability of electric vehicles, which is, however, limited by the propensity of lithium plating. The plated lithium can grow dendritically and may cause internal short and increase the risk of thermal runaway. In this study, a novel anode potential control strategy using a battery management system (BMS) has been demonstrated to enable fast charging in commercial pouch cells without lithium plating. Operando anode potential measurement using a 3-electrode configuration allows monitoring the occurrence of lithium plating. A novel 3-electrode cell analytics was developed to delineate the irreversible and irretrievable contributions to the total capacity loss and identify electrode-specific degradation mechanisms. The BMS algorithm dictates the charging current to maintain a positive anode potential and prevents lithium plating on the anode but fails to sufficiently control the cathode operating potential leading to irretrievable capacity loss. Operating the cell in conditions favorable to the anode may contrarily lead to cathode degradation and subsequent cell failure. Morphological and electrochemical characterizations reveal minimal anode degradation and a 2× higher cathode-capacity loss in the BMS-controlled cells. The baseline cell, not enabled with the BMS anode potential control strategy, exhibits extensive lithium deposition in the anode resulting in 7× higher anode-capacity loss. This study discovers the role of cathode-induced cell failure even when the anode-centric lithium plating is prevented and suggests pathways toward future BMS algorithm development enabling Li-ion cell operation under extremes. Fast charging of lithium-ion cells is key to alleviate range anxiety and improve the commercial viability of electric vehicles, which is, however, limited by the propensity of lithium plating.