Effect of support salts on apparent performance of Li metal anode in Ethylene carbonate/Ethyl methyl carbonate solvent and dynamic mechanism analysis

Abstract

Lithium metal batteries (LMB) have received widespread attention due to their high energy density and potential commercial value. The relationship between the rate performance, cycling performance, microstructure of the deposition layer, and SEI of lithium anodes has not yet been elucidated. Here, we investigated the cycling performance and rate characteristics of metal lithium anodes in classic carbonate electrolytes containing different supporting salts. And the microstructure and chemical information of the lithium anode surface were analyzed. In addition, microelectrode technology was used to study the dynamic behavior and reaction of electroplating/stripping lithium process under different polarization conditions (current density), revealing the apparent performance, microscopic visual information, and dynamic causes and mechanisms of SEI. The results indicate that in carbonate electrolytes containing LiBOB and LiPF6, the cycling performance of lithium anodes, the microstructure of the deposition layer, and SEI can be significantly improved. Microelectrode research has revealed a close causal relationship between the stability and coordination of each basic step, including lithium ion mass transfer, interface charge transfer, and surface crystallization kinetics parameters, and the apparent performance of lithium anodes. This correlation can serve as a dynamic evaluation basis for future selection and optimization of operating and manufacturing conditions.