High-efficiency mapping of resonant inelastic x-ray scattering of sodium-ion battery cathodes

High degree of reversibility [1] of the oxygen redox reactions in sodium-ion batteries (NIBs) makes them attractive candidates for large-scale energy storage solutions, provided that the oxygen activity can be optimized to significantly boost their capacity. High-efficiency mapping of resonant inelastic x-ray scattering (mRIXS) is a powerful tool for investigating the chemistry of NIBs [2, 3]. Tracking the energy of the emitted photons across an absorption edge introduces an extra dimension of information relative to the conventional x-ray absorption spectroscopy (XAS) studies, allowing for an unambiguous access to different decay channels, including unconventional oxidation states of oxygen and the transition metal, as well as the hybridization between them. Here, we demonstrate the oxygen K-edge RIXS maps of a model solid-state battery cathode system, NaNiO₂, as well as discuss perspectives for future in-operando measurements.



[1] C. Fang, Y. Huang, W. Zhang, J. Han, Z. Deng, Y. Cao, et al., Routes to high energy cathodes of sodium-ion batteries. Adv. Energy Mater. 6:1501727. (2016)

[2] W. Yang, and T. Devereaux, Anionic and cationic redox and interfaces in batteries: Advances from soft X- ray absorption spectroscopy to resonant inelastic scattering, J. Pow. Sour. 389, 188-197 (2018)

[3] J. Wu, Z.-X. Shen, and W. Yang, Redox mechanism in Na-ion battery cathodes probed by advanced soft X-ray spectroscopy. Front. Chem. 8:816 (2020)