Li Electrodeposition Modeling for Analyzing the Effect of Li+ Redistribution in Li Metal Secondary Batteries

Abstract

To meet the high-energy-density requirement of Li secondary batteries for EV applications, Li metal is still being re-examined extensively beyond conventional carbon-based anode active materials. However, unlike intercalation mechanism-based anodes, Li metal anodes (LMAs), suffering from significant surface morphology changes during electroplating and stripping, can accompany several issues such as Li dendrite growth and continuous side reactions, thereby leading to the poor electrochemical performance and cycle stability. Among various reasons of the Li dendrite formation, inhomogeneous and slow Li+ transport to the LMAs are representatively known, accelerating irregular electrodeposition and rapid Li+ depletion on the LMA surface.In this study, we attempted to simulate Li dendrite growth under practical current conditions by developing a 2D Li electrodeposition model. Based on this model, we analyzed the geometric-electrochemical characteristics of Li metal interface depending on Li+ concentration distribution in the electrolyte and SEI. Furthermore, in order to verify a nanomaterial-based micro-convection effect in the electrolyte for improving mass transfer, the Li+ concentration change nearby the interface was calculated while simulating the Li dendritic growth. Also, real 2D morphologies of the Li dendrites were reconstructed and analyzed together in a similar way. As a result, the micro-convection enables relatively uniform Li+ distribution at the LMA interface and enhances the mass transport in the electrolyte, which can suppress the Li dendrite growth even at 5.0 mA cm-2.