Electrolyte-Induced Interfacial/Bulk Dual Regulation Enables Negligible Capacity Decay in Li-Rich Cathodes.

Abstract

Lithium-rich manganese-based oxides (LRMO) suffer from rapid capacity decay, mainly driven by interfacial instability and bulk structural degradation associated with Jahn-Teller (J-T) distortion in Mn3+-rich regions. Such distortion accelerates surface oxygen activity, triggers nonuniform cathode electrolyte interphase (CEI) formation along with promoted parasitic reactions. Herein, we develop an electrolyte‑induced interfacial/bulk dual regulation strategy that enables negligible capacity decay in Li‑rich cathodes via coordinated interfacial/bulk regulation. In situ characterizations combined with interfacial compositional analyses confirm the dynamic formation of a thin, uniform, and robust LiF/LiBO2-rich CEI, which stabilizes surface oxygen species and suppresses interfacial side reactions. Meanwhile, local structural analyses combined with theoretical calculations reveal that fluorinated molecules regulate Mn into a low-spin configuration, thereby alleviating J-T distortion and preventing bulk structural degradation. Benefiting from this dual induced interfacial-bulk stabilization effect, LRMO||Li cells deliver an initial capacity of 219.6 mAh g-1 and retain 97.6% of their capacity after 400 cycles. This work provides a new pathway toward electrolyte-mediated dual stabilization and demonstrates the feasibility of mitigating capacity decay in Li-rich cathodes via electrolyte-induced interfacial/bulk regulation.