Abstract
NaxMeyOz oxides have attracted wide attention as promising cathode materials for sodium-ion batteries because of their potential high capacity and rate capability (1). The stable cycling performance, usually obtained within a low voltage range, drastically decrease when cycled at high voltage range despite the large initial charge capacity. Thus, it has been suggested that besides storing charge on the transition metal ions, oxygen ions can also participate in the charge compensation mechanisms at high voltage which induces an oxygen loss from the lattice when charging which is the reason behind the poor cycling stability (2).
In this work, the aim is to investigate the anionic redox reactions of Na2Mn3O7 cathode material, within the voltage window of 1.5 – 4.5 V using combined soft X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) which allow us to study the electronic structure of this material.
Keywords: Energy, Storage, Sodium-ion, Cathode, layered oxide, anionic redox, oxygen activity.
References:
Delmas, C., Braconnier, J.-J., Fouassier, C. & Hagenmuller, P. Electrochemical intercalation of sodium in NaxCoO2 bronzes. Solid State Ionics. 3/4, 165–169 (1981)
Assat, G. & Tarascon, J. Fundamental understanding and practical challenges of anionic redox activity in Li-ion batteries. Energy3, 373–386 (2018).
Acknowledgements: The Swedish Research Council (VR) financially supported this work via project 2017-05466