Effect of Mg2+ substitution on the oxygen redox activity of Fe-Mn-based P2-layered oxides as cathode materials for Sodium-ion Batteries: a R

Sodium-ion batteries (SIBs) have emerged as a promising alternative to Lithium-ion batteries (LIBs) due to the widespread availability of sodium. P2-layered oxides are attractive cathode materials for SIBs, offering tunable electrochemical properties. However, their long-term stability is hindered by phase transitions occurring at high voltages (>4V), possibly due to oxygen redox activity, which can degrade performance. Introducing Mg²⁺ into P2-Na0.67Mn0.5Fe0.5-xMgxO2 has shown potential in enhancing structural stability by preventing the collapse of transition metal layers and regulating oxygen redox activity. Despite these benefits, the precise effects of Mg²⁺ remain unclear. This proposal aims at employing XAS and RIXS techniques to analyze electrodes at various charge states and Mg concentrations, providing deeper insights into its influence on redox behavior and structural evolution during cycling.