Improvement in the Electrochemical Properties of Lithium Metal by Heat Treatment: Changes in the Chemical Composition of Native and Solid Electrolyte Interphase Films

Abstract

This study aims to improve the electrochemical properties of lithium metal for application as a negative electrode in high-energy-density batteries. Lithium metal was heat-treated at varying temperatures to modify the native and solid electrolyte interphase (SEI) films, which decreased the interfacial resistance between the lithium electrode and electrolyte, thereby improving the cycling performance. Moreover, the influence of the native and SEI films on lithium metals depended on the heat-treatment temperature. Accordingly, X-ray photoelectron spectroscopy (XPS) was performed to investigate the chemical composition of the native and SEI films on the heat-treated lithium metals before and after immersion in an organic electrolyte solution. The XPS results revealed the high dependence of the chemical composition of the outer layer of the native and SEI films on the heat-treatment temperature, implying that the native and SEI films can be effectively modified by heat treatment.

Current Status and Future Perspective on Lithium Metal Anode Production Methods

“…This layer is composed of various lithium compounds such as Li 2 O, Li 2 CO 3 , and LiOH, which are commonly formed on lithium metal even in an inert atmosphere. The performance of native and SEI films on lithium metal could be significantly enhanced through appropriate heat treatment during extrusion of the lithium ingot, [ 90 ] by flattering the topography of the electrodes by roll‐press technique, [ 91 ] by modifying the surface of the chemistry of the native layer [ 92 ] or by removing it. [ 93 ] Other approaches have employed structured (either pillars or pyramids) to force the deposition of the Li alongside these wall structures [ 94 ] or have tuned the mechanical methods for the obtention of lithium electrodes with {110} texturing.…”

Enhancing Electrochemical Characteristics of Li‐Metal Electrodes: The Impact of Pre‐Treatment via CO2 Gas Reaction

“…This native film, comprising inorganic compounds such as Li 2 CO 3 , LiOH, and Li 2 O, significantly affected the properties of the SEI film formed during the electrochemical reactions [23,24] . The migration characteristics of Li ions in these compounds have been the subject of intensive study through theoretical methods, such as molecular dynamics simulations and in particular, facilitates rapid Li‐ion diffusion through knock‐off mechanisms in inorganic material‐based SEI layers, thereby serving as an exemplary migration medium for Li ions at potentials close to those of Li metal redox reactions [24–27] …”

“…[23,24] The migration characteristics of Li ions in these compounds have been the subject of intensive study through theoretical methods, such as molecular dynamics simulations and in particular, facilitates rapid Li-ion diffusion through knock-off mechanisms in inorganic material-based SEI layers, thereby serving as an exemplary migration medium for Li ions at potentials close to those of Li metal redox reactions. [24][25][26][27] In this context, this study proposes a straightforward yet effective method to enhance the electrochemical plating/ stripping mechanisms of Li metal by fostering the formation of Li 2 CO 3 on its surface through CO 2 gas pre-treatment. This approach not only promotes Li 2 CO 3 as a key component of the native film, but also offers significant commercial advantages owning to its simplicity, minimal pollution, and waste.…”