2020/11/12 by Green, R. J., Wadati, H., Regier, T. Z. +7 · 1 citation
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2011.06441
The electronic structure of LiNiO2, a promising Li-ion battery cathode material, has remained a challenge to understand due to its highly covalent yet correlated nature. Here we elucidate the electronic structure in LiNiO2 and the related compound NaNiO2 using x-ray absorption spectra (XAS) and quantum many-body calculations. Notably, we use inverse partial fluorescence yield to correctly measure the Ni L-edge XAS, which is inaccurate using conventional methods. We show that the XAS are indicative of a strong Jahn-Teller effect in NaNiO2 and a bond disproportionated state in LiNiO2, supporting a theory of a high-entropy, glassy disproportionated state that stabilizes charging cycles in LiNiO2.