Substrate effects on Li+ electrodeposition in Li secondary batteries with a competitive kinetics model

Abstract

A Li₂₂Sn₅ alloy was prepared as a novel substrate of the metallic Li anode of rechargeable Li batteries for Li⁺ deposition. The performance of this alloy substrate was compared with those of Li, Cu, and Sn substrates. The deposition–stripping cycling performance of Li on the substrates was studied through the galvanostatic charge–discharge method and cyclic voltammetry. The morphologies of the substrates before and after Li⁺ deposition were investigated through scanning electron microscopy and digital video microscopy. The electrochemical kinetics of Li⁺ electrodeposition on the different substrates was studied through the galvanostatic pulse method and linear sweep voltammetry. The solid electrolyte interface films of Li deposits on the substrates were characterized through electrochemical impedance spectroscopy. Results show that Li₂₂Sn₅ is an excellent substrate for metallic Li electrodes. “The competitive kinetics model” was proposed as a novel mechanistic model to explain the electrodeposition behavior of Li⁺ on general substrates based on electrochemical kinetic principles.