The Effects of Temperature and Cell Parameters on Lithium-Ion Battery Fast Charging Protocols: A Model-Driven Investigation

Abstract

The risk of lithium plating is a key barrier to lithium-ion battery fast charging. Among other strategies, many alternative charging protocols have been proposed to reduce the plating propensity compared to the conventional constant current-constant voltage (CC-CV) protocol. However, conflicting results have been reported on their impacts on battery lifetime. This work investigates the performance of CC-CV and a boost charging protocol using an electrochemical-thermal model which accounts for nonlinear diffusion and reversible lithium plating. The relative performance of the protocols is found to ultimately depend on the solid phase and ion diffusion timescales. Boost charging is beneficial when both these timescales are short, i.e. in power cells in general or in energy cells at sufficiently high temperatures. The high concentration gradients that develop during the boost stage can sufficiently relax in the subsequent lower current stage to reduce the plating propensity in these cases. When the diffusion timescales are long, boost charging leads to increased plating heterogeneity (driven by the ion diffusion limitations) and slightly increased plating propensity (driven by the solid phase diffusion limitations). Our findings highlight the need to study alternative charging protocols at a wide range of conditions and on different cells before practical deployment.