AUTHOR=Gorbunov Mikhail V. , Carocci Salvatore , Gonzalez Martinez Ignacio G. , Baran Volodymyr , Mikhailova Daria 

TITLE=Studies of Li2Fe0.9M0.1SO Antiperovskite Materials for Lithium–Ion Batteries: The Role of Partial Fe2+ to M2+ Substitution

JOURNAL=Frontiers in Energy Research

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2021.657962

DOI=10.3389/fenrg.2021.657962

ISSN=2296-598X

ABSTRACT=<p>Cubic Li<sub>2</sub>Fe<sub>0.9</sub>M<sub>0.1</sub>SO antiperovskites with M–Co<sup>2+</sup>, or Mn<sup>2+</sup> were successfully synthesized by a solid-state technique, and studied as cathode materials in Li-batteries. The influence of the Co, and Mn cation substitution of Fe in Li<sub>2</sub>FeSO on the resulting electrochemical performance was evaluated by galvanostatic cycling, while the reaction mechanism was explored by applying <italic>operando</italic> X-ray absorption and X-ray diffraction techniques using synchrotron radiation facilities. Even 10% Fe-substitution by these metals completely changes the structural behavior of the material upon Li-removal and insertion, in comparison to Li<sub>2</sub>FeSO. The Co-substitution significantly improves cyclability of the material at high current densities in comparison to the non-substituted material, reaching a specific capacity of 250 mAh/g at 1C current density. In contrast, the Mn-substitution leads to deterioration of the electrochemical performance because of the impeded kinetics, which may be caused by the appearance of a second isostructural phase due to formation of Jahn-Teller Mn<sup>3+</sup> cations upon delithiation.</p>