Experimental and theoretical advances of high-efficiency RIXS for energy storage materials*

Electrodes based on transition-metal (TM) oxides have dominated the electrochemical devices as both cathodes in batteries and electrocatalyst in fuel cells. However, the demand towards high-energy performance of energy storage devices has driven the TM oxide system into unconventional conditions in both the cationic and anionic redox states. Recent demonstrations have shown that high-efficiency mapping of RIXS (mRIXS) is a powerful technique to reveal both the TM and O redox states in battery electrodes. This presentation will discuss the recent findings on the surface and bulk activities of Li₂MnO₃ system in both Mn and O, which naturally leads to a further analysis of the critical RIXS features through theoretical calculations. Our results show that many of our fundamental understandings of TM oxide based electrode are questionable, and a new model on how to understand the novel states in oxide electrodes under high potential will be proposed.