Tracking lithium plating-induced health degradation based on battery dynamics

Abstract

Accurate online diagnostics of Li plating-induced degradation are essential to maximize lifespan of batteries and ensure safe operation of electric vehicles. This study proposes a diagnostic tool for tracking Li plating-induced degradation of Li-ion batteries, based on dynamic current responses to voltage perturbations. A unique health indicator (Δα), which can effectively distinguish Li plating-induced degradation from interphase growth and active material loss, is extracted from current trajectories at intermittent check-up stages. The feasibility of the proposed method is experimentally validated using cylindrical [graphite || LiNi<inf>0.6</inf>Co<inf>0.2</inf>Mn<inf>0.2</inf>O<inf>2</inf>] batteries. The batteries suffering from Li plating during fast-charging exhibit a distinctive two-stage behavior of Δα with capacity loss. Computational simulations reveal that a highly tortuous Li layer plated on top of the negative electrode impedes electrolyte mass transfer process and causes rapid depletion of Li ions in the vicinity of the graphite particles, thereby producing characteristic current trajectories for Li plating-induced degradation.