Extended Chemical Flexibility of Cubic Anti-Perovskite Lithium Battery Cathode Materials

Abstract

Novel bichalcogenides with the general composition (Li₂TM)ChO (TM = Mn, Co; Ch = S, Se) were synthesized by single-step solid-state reactions. These compounds possess cubic anti-perovskite crystal structure with Pm3̅ m symmetry; TM and Li are disordered on the crystallographic site 3c. According to Goldschmidt tolerance factor calculations, the available space at the 3c site is too large for Li⁺ and TM²⁺ ions. As cathode materials, all title compounds perform less prominent in lithium-ion battery setups in comparison to the already known TM = Fe homologue; e.g., (Li₂Co)SO has a charge density of about 70 mAh g^-1 at a low charge rate. Nevertheless, the title compounds extend the chemical flexibility of the anti-perovskites, revealing their outstanding chemical optimization potential as lithium battery cathode material.