Electrolyte additive engineering for lithium-rich manganese-based oxide cathodes: Interfacial failure mechanisms and molecular design principles

Lithium-rich manganese-based oxide (LRMO) cathodes have emerged as promising candidates for lithium batteries with high energy density, but their severe high-voltage interfacial instability in conventional electrolytes limits their practical application. Electrolyte additives can mitigate these coupled degradation pathways at low concentrations, yet their LRMO-specific molecular design principles remain insufficiently clarified. This review critically summarizes the rational design of electrolyte additives for stabilizing LRMO cathodes. It discusses the electrochemical evolution of LRMO cathodes, the origins of interfacial degradation, and electrolyte failure from the perspectives of cathode–electrolyte interface (CEI) instability, oxygen-related parasitic reactions, and LiPF 6 -derived side reactions. Additives are categorized by function, including CEI construction, oxygen species regulation, LiPF 6 stabilization, and multifunctional control, with emphasis on design principles, synergistic roles in mitigating coupled interfacial degradation and voltage fade, and extension to polymer-based solid electrolytes. Future directions include operando characterization, quantitative descriptors, and mechanism-integrated design.