Theoretical understanding of oxygen redox feature observed on RIXS map of battery cathode materials*

High energy density rechargeable batteries are essential to meet the ever growing global energy demand. Recently, cathode materials which have redox activity of both transition metal and oxygen are found to be very promising in this regard. However, the exact mechanism for the oxygen redox is yet to be understood. Resonant inelastic x-ray scattering (RIXS) has been established as a reliable probe of the critical oxygen states involved in battery electrodes with oxygen redox activities. The interpretation of specific O -K RIXS features; however, has not yet been achieved. To this end, we have performed theoretical calculations using new algorithm we developed to understand the spectroscopic feature from first principle. We aim to shed light on the physics of cathode materials and suggest design schemes for cathodes with exceptional capacity.