Unlocking low-temperature stable cycling of ultrahigh-nickel LiNi_0.91Co_0.06Mn_0.03O₂ cathodes by modulating interfacial chemistry through coordination environment

Ultrahigh‑nickel layered oxides (NCM, Ni ≥ 0.9) are considered promising next-generation cathodes because of their high energy density. However, their performance at sub-zero temperatures is severely limited by the high Li⁺ desolvation barrier at the cathode surface and interfacial structural instability. Herein, a dual-additive strategy utilizing ethyl vinyl sulfone (EVS) and difluoroethylene carbonate (DFEC) is employed to reconstruct the cathode-electrolyte interphase (CEI) via solvation structure modulation, thereby enhancing the cyclability of LiNi_0.91Co0.06Mn_0.03O₂. The synergistic interaction of EVS and DFEC optimizes the solvation sheath by reducing coordinated solvent molecules and free PF₆⁻. Consequently, an in situ derived bilayer CEI is formed, which facilitates interfacial Li⁺ transport kinetics and effectively suppresses parasitic reactions by continuously scavenging lattice oxygen. With this tailored electrolyte, NCM||Li half-cells exhibit 74.7% capacity retention after 500 cycles at 25 °C and maintain 93% capacity under −20 °C cycling conditions. Furthermore, 1.4 Ah NCM||Graphite pouch cells demonstrate 82.5% capacity retention after 500 cycles. These findings provide a robust strategy for achieving long-term stability of ultrahigh nickel cathodes in low-temperature applications.