Bulk/Interfacial Structure Design of Li-Rich Mn-Based Cathodes for All-Solid-State Lithium Batteries

Li-rich Mn-based cathode materials (LRMO) are promising for enhancing energy density of all-solid-state batteries (ASSBs). Nonetheless, the development of efficient Li⁺/e^- pathways is hindered by the poor electrical conductivity of LRMO cathodes and their incompatible interfaces with solid electrolytes (SEs). Herein, we propose a strategy of <i>in</i>-<i>situ</i> bulk/interfacial structure design to construct fast and stable Li⁺/e^- pathways by introducing Li₂WO₄, which reduces the energy barrier for Li⁺ migration and enhances the stability of the surface oxygen structure. The reversibility of oxygen redox was improved, and the voltage decay of the LRMO cathode was addressed significantly. As a result, the bulk structure of the LRMO cathodes and the high-voltage solid-solid interfacial stability are improved. Therefore, the ASSBs achieve a high areal capacity (∼3.15 mAh/cm²) and outstanding cycle stability of ≥1200 cycles with 84.1% capacity retention at 1 C at 25 °C. This study offers new insights into LRMO cathode design strategies for ASSBs, focusing on ultrastable high-voltage interfaces and high-loading composite electrodes.