2000 character limit reached
Evidence for bond-disproportionation in LiNiO2 from x-ray absorption spectroscopy (2011.06441v1)
Published 12 Nov 2020 in cond-mat.str-el and cond-mat.mtrl-sci
Abstract: The electronic structure of LiNiO$_2$, 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 LiNiO$_2$ and the related compound NaNiO$_2$ 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 NaNiO$_2$ and a bond disproportionated state in LiNiO$_2$, supporting a theory of a high-entropy, glassy disproportionated state that stabilizes charging cycles in LiNiO$_2$.