Reconstructing Inorganic‐Rich Interphases by Nonflammable Electrolytes for High‐Voltage and Low‐Temperature LiNi_0.5Mn_1.5O₄ Cathodes

Abstract Cobalt‐free and spinel LiNi_0.5Mn_1.5O₄ (LNMO) cathodes commonly suffer from undesirable solvent decomposition, serious transition‐metal dissolution, and unstable cathode electrolyte interphase (CEI) layers, incurring rapid capacity decay at high voltages and low temperatures. Herein, these issues are well addressed by utilizing fluorinated solvents with a low coordination number and ethyl propionate with a low melting point. A Li₂CO₃/LiF‐rich heterostructured CEI layer, which possesses good electron blocking capability of LiF, fast Li⁺ transport kinetics of Li₂CO₃ and good mechanical stability, is generated by the synergistic decomposition of hybrid solvents. The robust, homogeneous, and well‐balanced CEI layers subsequently prevent catalyzed parasitic side reactions, prohibit transition‐metal dissolution, and ensure fast interfacial reaction kinetics crossover to the LNMO cathode, thus improving its cycling stability. Consequently, the LNMO cathode delivers a high‐capacity retention of 95.8% over 500 cycles at 25 °C and 97.5% after 180 cycles at −20 °C. This work provides an encouraging alternative to design the high‐voltage and low‐temperature electrolyte for pushing the ongoing research to stabilize Co‐free LNMO materials toward practical applications.