Investigation into the Surface Chemistry of Li₄Ti₅O₁₂ Nanoparticles for Lithium Ion Batteries

Abstract

Elucidating surface chemistry of Li₄Ti₅O₁₂ anode material plays a critical role in solving gas evolution in Li₄Ti₅O₁₂-based lithium ion batteries. Herein, we propose a CO₂ cycloaddition reaction to study the surface chemistry of Li₄Ti₅O₁₂ nanoparticles. Through the reaction, bare Li₄Ti₅O₁₂ nanoparticles were demonstrated to have extensive Lewis-acid sites, that is, dangling Ti bonds or hydroxyl groups. Lewis-acid site is considered to be able to initiate the decomposition of electrolyte solvents and may also serve as one of the main reasons for gas evolution. TiN_x coating layer is used to cover up the Lewis-acid site and is able to decrease yield of the cycloaddition reaction to some extent. These findings may provide a simple yet very effective way to evaluate surface chemistry and gas evolution in other lithium ion batteries, not limited to Li₄Ti₅O₁₂-based batteries.