Role of Copper as Current Collectors in the Reductive Reactivity of Polymers for Anode-Free Lithium Metal Batteries - Insights from DFT and AIMD Studies

Abstract

Understanding the role of current collectors (CCs) in the reductive reactivity of polymers on Li metal and the resultant solid electrolyte interphase (SEI) formation is essential for improving the performance of anode-free lithium metal batteries (AFLMBs). In this study, we have examined the reactivity of three polymeric hosts: poly(ethylene oxide) (PEO), poly(ε-caprolactone) (PCL), and poly(trimethylene carbonate) (PTMC) at Li metal supported on Cu surfaces (Li/Cu) using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. In particular, the effect of copper (Cu) CCs on polymer stability, electronic structure, and their reduction reactions is investigated and compared to that of pure Li (100) surface. Through time-dependent Bader charge transfer analysis, electron transfer is identified as the triggering factor for polymer reduction. Based on the simulations, we find that the Cu CCs have a significant influence on the charge distribution of the Li metals, which increases electron transfer to the polymers and thereby accelerates polymers reduction. This thereby leads to different reaction mechanisms as compared to on Li-metal. The findings suggest that utilization of Cu CCs avoid production of CO molecules and improves the quality of the formed SEI layer. Figure 1