Entropic electrolyte engineering for stabilizing the cathode-electrolyte interphase in high-voltage lithium-rich cathodes

The application of lithium-rich manganese-based layered oxides (LRMOs) in high-energy lithium-ion batteries is limited by severe interfacial degradation and structural instability under high-voltage operation. Guided by theoretical calculations, a high-voltage-tolerant high-entropy (HTHE) electrolyte is designed to enable the formation of a chemically robust and functionally integrated cathode-electrolyte interphase (CEI). The electrolyte system incorporates multiple components containing fluorine, boron, sulfur, and nitrogen, which synergistically participate in interphase construction and interfacial stabilization. The CEI formed under the HTHE environment effectively mitigates oxygen release, transition metal dissolution, and irreversible phase transitions. Combined evidence from in-situ and ex-situ characterizations across multiple scales confirms that the CEI maintains the layered structure, enhances redox reversibility, and suppresses harmful phase transformation during prolonged cycling. As a result, the electrochemical performance of the LRMOs is significantly improved, with the capacity retention increasing from 73.87% in the conventional electrolyte to 85.82% in the HTHE system after 100 cycles at a cutoff voltage of 4.8 V. These findings highlight the importance of electrolyte-driven interphase engineering in stabilizing high-voltage cathodes. The proposed entropic formulation strategy provides a rational and broadly applicable approach for constructing functional CEIs and offers valuable guidance for the development of next-generation lithium-ion batteries with enhanced durability and energy density.