Modulating Redox Pathways in Manganese-Based Disordered Rocksalt Cathodes via Molybdenum Incorporation

Abstract Cation-disordered rocksalt oxides offer broad compositional flexibility and high theoretical capacities, but their electrochemical performance is often limited by uncontrolled competition between transition metal and oxygen redox processes. In particular, controlling the balance between Mn and O redox activities remains a key challenge in Mn-based disordered oxides. Here, a previously unexplored compositional space in the Li−Mn−Mo−O system is investigated, revealing that Mo incorporation systematically alters the electronic structure and redox behavior of Mn-based disordered rocksalt oxides. Mo doping lowers the average Mn oxidation state, thereby stabilizing a Mn-dominated charge-compensation mechanism. Combined spectroscopic characterization and first-principles calculations reveal a shift in charge compensation from oxygen-centered to Mn-centered redox processes with Mo doping. As a result, Li1.25Mn0.5Mo0.25O2 delivers a reversible capacity exceeding 300 mAh g−1 with enhanced electrochemical stability. These findings demonstrate that targeted compositional and electronic structure modulation enables effective control of redox pathways in cation-disordered oxides and offers design principles for stable, high-capacity Mn-based cathode materials.