Nucleophilic Oxygen‐Engineering Dual‐Gradient Cathode‐Electrolyte‐Interphase for High‐Voltage Lithium‐Rich Manganese Oxide Cathodes

The high-voltage stability of lithium-rich manganese-based layered oxide (LRMO), particularly at voltages approaching 4.8 V, is governed by the structure of the cathode electrolyte interphase (CEI), the oxidative stability of the electrolyte, and lattice degradation caused by transition metals dissolution. In this work, a molecular engineering strategy is employed to design nucleophilic oxygen-functionalized additives that construct a dual-gradient inorganic CEI, effectively modulate interfacial redox reactions, and stabilize the lattice Mn dissolution of the LRMO cathode. Driven by the strong electron-donating characteristics of the nucleophilic species, the engineered CEI exhibits a robust and zipper-like architecture composed of an inner lithium borates-rich layer and an outer lithium phosphates-dominated layer, promoting fast Li⁺ transport and enhancing interfacial kinetics. The nucleophilic oxygen-driven electrolyte mitigates oxidative degradation and suppresses Mn dissolution, enabling LRMO cathodes to exhibit a reversible capacity retention of 80% after 580 cycles at a high-voltage of 4.8 V-class. This work provides the efficiency of nucleophilic oxygen-mediated interfacial engineering in enabling durable high-voltage operation of LRMO cathodes.