Electron‐Donating Effect Derived Stable Homogeneous Electrode/Electrolyte Interface for Ultra‐High Voltage Stable Lithium Metal Batteries

Abstract The development of highly stable electrolytes capable of withstanding elevated cut‐off voltages is crucial for advancing the energy density of lithium‐metal batteries (LMBs). Current limitations stem from irreversible reactions like unstable electrode/electrolyte interfaces and lattice oxygen release under high‐voltage conditions. Herein, a pioneering electron‐donating electrolyte design strategy featuring compressed solvated shells is proposed to address the high‐voltage cyclic instability challenges. Through systematic investigation of solvents and interface evolutions induced by polarization effects, the fundamental mechanisms governing high‐voltage performance enhancement are clearly elucidated. Crucially, this approach also increases the proportion of high charge‐density components, effectively mitigating charge deficiency and suppressing lattice oxygen oxidation at high potentials. The optimized electrolyte facilitates formation of a stable, homogeneous cathode/electrolyte interface, significantly reducing electrolyte decomposition while enabling balanced complex‐ion transport kinetics. When implemented in LiNi 0.6 Co 0.2 Mn 0.2 O 2 ‖Li‐metal cells, the system demonstrates an exceptional initial capacity of 225.1 mAh g −1 at ultrahigh voltage of 4.8 V, with 87.1% capacity retention after 150 cycles at 1C. Full‐cell configurations still maintain stable operation for over 400 cycles at 4.7 V, establishing a practical pathway for ultrahigh‐voltage LMB, which is also confirmed by applying LiNi 0.5 Mn 1.5 O 4 , LiCoO 2 , and NCM811 cathode. This insight provides implementable electrolyte modification principles for advancing high‐energy‐density battery systems.