Achieving Excellent Electrochemical Stability of Li‐rich Mn‐Based Cathode by One‐Step Decanoic Acid Treatment Under Ambient Atmosphere

ABSTRACT High‐capacity layered Li‐rich Mn‐based oxides (LLMO) materials suffer irreversible lattice oxygen loss, voltage decay, and rapid capacity decay during the cycling process, which severely hinder their practical application. This study proposes a one‐step decanoic acid treatment strategy without further process (i.e., sintering, washing, etc.), to modify the near‐surface of Li‐rich Mn‐based materials (Li _1.2 Mn _0.54 Ni _0.13 Co _0.13 O ₂ ). The investigation reveals that decanoic acid preferentially neutralizes surface residual lithium and evenly adheres to the material surface. This subsequently participates in forming a thin and stable cathode electrolyte interphase (CEI) film and provides stable surface oxygen vacancies during cycling, effectively suppressing the electrode/electrolyte interfacial side reactions and improving the structural stability. Comparing with the pristine LLMO (270.6 mAh g ⁻¹ initial capacity at 0.1 C, 68% capacity retention after 200 cycles at 1 C), the prepared DA‐LLMO shows significantly enhanced discharge specific capacity and cycling stability (293.5 mAh g ⁻¹ initial capacity at 0.1 C, 93% capacity retention after 200 cycles at 1 C). Furthermore, experimental results demonstrate that this method exhibits a certain degree of general applicability for other cathodes (LiCoO ₂ and Ni‐rich oxide). This work establishes a novel approach for near‐surface design of high‐energy‐density lithium‐ion batteries.