Studies of Li2Fe0.9M0.1SO Antiperovskite Materials for Lithium–Ion Batteries: The Role of Partial Fe2+ to M2+ Substitution
Mikhail V. Gorbunov, Salvatore Carocci, Ignacio Guillermo Gonzalez Martinez, Volodymyr Baran, Daria Mikhailova
Abstract
Cubic Li 2 Fe 0.9 M 0.1 SO antiperovskites with M–Co 2+ , or Mn 2+ 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 2 FeSO on the resulting electrochemical performance was evaluated by galvanostatic cycling, while the reaction mechanism was explored by applying operando 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 2 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 3+ cations upon delithiation.