Low‐Concentration Highly Aggregated Solvation Structure Design for Stabilizing Ni‐Rich Single‐Crystal Cathodes

ABSTRACT Ni‐rich single‐crystal layered oxides are promising cathodes for high‐energy lithium batteries. However, under high‐voltage operating (>4.3 V), they often suffer from severe structural degradation, leading to impedance buildup and rapid capacity fading. In this study, we design a low‐concentration yet highly aggregated electrolyte that enables the formation of a thin, uniform, and inorganic‐rich cathode electrolyte interphase (CEI), thereby mitigating high‐voltage‐induced surface reconstruction of single‐crystal NMC83. Benefiting from the contact ion pair/aggregate (CIP/AGG)‐dominated solvation environment, with 90.6% anion‐associated Li + species confirmed by molecular dynamics simulations, Li||NMC83 cells deliver 215.4 mAh g −1 at 4.5 V and retain 85.0% capacity after 200 cycles, outperforming EC/EMC‐based counterparts by nearly 40%. Notably, the electrolyte maintains stable operation from −20 to 45°C, further highlighting its capability for high‐voltage cathode interfacial stabilization. This work offers new insight into stabilizing high‐voltage single‐crystal cathodes through solvent–anion coordination chemistry.