Oral Presentation Royal Australian Chemical Institute National Congress 2026

Lithium-carbon dioxide (Li-CO₂) batteries are promising next-generation energy storage systems with high theoretical energy density and potential for CO₂ capture and conversion. However, their practical application is hindered by sluggish CO₂ redox kinetics and unstable electrolyte/electrode interfaces. This presentation outlines comprehensive electrolyte engineering strategies to address these challenges. Unlike conventional lithium-ion batteries, Li-CO₂ cells utilize porous cathodes that can breathe CO₂. However, the lack of systematic studies on electrolyte design leaves several unresolved issues, such as the formation mechanism of the solid electrolyte interphase (SEI) and solvent selection principles. We first investigated solvents with different donor numbers and varying salt concentrations to examine their influence on SEI composition, solvation structures, and electrochemical performance.¹ Beyond conventional fluorinated SEIs, we uncovered a catalytic role of in-situ formed C-N species in the SEI on the cathode, which act as bidirectional charge transfer bridges, accelerating Li₂CO₃ formation/decomposition and improving reversibility.² Furthermore, we propose a decoupled electrolyte strategy by introducing TEGDME as a co-solvent in a DMF matrix. By regulating the electrostatic potential distribution of solvated Li⁺ clusters, selective interfacial adsorption of TEGDME was achieved, creating a chemically inert, stable environment at the cathode that suppresses DMF-related side reactions.³ These findings offer new design principles for high-performance electrolytes in Li-CO₂ batteries and pave the way for future applications in metal-gas batteries.