Structural and Electronic Origins Enabling Chlorine Anion Redox in Halide Cathodes

ABSTRACT

Anion redox has been shown to increase specific capacity in oxide and sulfide cathodes; however, its existence in chloride‐based systems remains an open question. Using Li ₂ FeCl ₄ as the role model, this work investigates potential chlorine anion redox by meticulous structural analysis combined with computational electronic evidence. pDOS and COHP reveal filled nonbonding orbital localization on anion. Electron extraction leads to [FeCl ₆ ] ⁿ⁻ octahedra distortions as evidenced by pre‐edge analysis and theoretical structural optimizations. The observed reductive coupling between iron and chlorine reflects their electronic interaction and charge compensation mechanism. Extending beyond current studies focused on chalcogens, these findings have broadened the scope for the future of anion redox into the chloride family.