Thickly and densely sintered Li_3xLa_2/3−xTiO₃ electrodes for the anode of Li-ion batteries

Abstract

Thickly and densely sintered electrodes (TDSE) consisting of active materials can achieve highly capacitive Li-ion batteries and are one of the ideal electrode structures applicable for co-sintered-type solid-state batteries based on oxide-based solid electrolytes. This study focused on Li_3xLa_2/3−xTiO₃ (LLTO) as the TDSE for the anode. LLTO exhibits high Li-ion conductivity and a high capacity of 225 mAh g⁻¹ with an operation potential below 1 V (vs. Li⁺/Li). However, the electronic conductivity of LLTO is low (less than 10⁻⁸ S cm⁻¹), and the improved electronic conductivity seems necessary. In this paper, we investigated the electrochemical properties of LLTO sintered electrodes and improved the electronic conductivity of LLTO by Mn substitution for the Ti site. LLTO shows a huge overpotential during initial Li insertion due to low electronic conductivity of 1.1 × 10⁻⁹ S cm⁻¹, resulting in extremely low capacity. On the other hand, Mn substitution enhances the electronic conductivity, resulting in improved first-cycle charging properties.