Novel understanding of carbothermal reduction enhancing electronic and ionic conductivity of Li4Ti5O12 anode

Abstract

Spinel Li₄Ti₅O₁₂ performance highly depends on both the electronic and ionic conductivity, however, developing a low-cost strategy to improve its electronic and ionic conductivity still remains challenging. In this study, a facile cost-saving carbothermal reduction method is introduced to synthesize the microscaled spinel Li₄Ti₅O₁₂ particles with the surface modification of Ti(III) using anatase–TiO₂, Li₂CO₃, and acetylene black (AB) as precursors. Remarkably, this ingenious design can easily eliminate the influence of the residual carbon, and thus makes it possible to individually study the effect of the Ti(III) on the bulk Li₄Ti₅O₁₂. To reveal the role of the Ti(III), the electronic conductivity and lithium-ion diffusion coefficient of the as-prepared materials were measured using a direct volt-ampere method, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results indicate that the carbothermal reduction leads to the increased electronic and ionic conductivity of the spinel Li₄Ti₅O₁₂. As a result, the modified Li₄Ti₅O₁₂ exhibits an enhanced cyclic stability, improved rate capability, and high Coulombic efficiency. The carbothermal reduction mechanism discreetly clarified in this study is beneficial to improving Li₄Ti₅O₁₂ performance for further commercial applications.