Mechanistic underpinnings of thermal gradient induced inhomogeneity in lithium plating

Abstract In the pursuit to enable the rapid charging of lithium-ion batteries, lithium plating at the anode poses one of the most significant challenges. Additionally, the heat generation that accompanies high rate battery operation in conjunction with non-uniform cooling and localized heating at tabs is known to result in thermal inhomogeneity. Such thermal anomalies in the absence of proper thermal management can instigate accelerated degradation in the cell. In this work, a physics-based interrogation of the link between thermal gradient induced inhomogeneity and lithium plating during charging is presented. The relative importance of in-plane vs. through-plane (inter-electrode) thermal gradients to charging performance and cell degradation is necessary to intelligently design packaging and cooling systems for large-format cells. While in-plane thermal gradients strongly influence active material utilization, the lithium plating severity was found to be very similar to an isothermal case at the same mean temperature. By contrast, interelectrode thermal gradients cause a shifting on the solid phase potential at each electrode during charging, related to the increase or decrease in overpotential due to local temperature variation. When the cathode temperature exceeds the anode temperature, lithium plating is exacerbated, and accelerated degradation occurs.