Li 2 O–B 2 O 3 –Li 2 SO 4 Fast‐Ion Conducting Coating Enables Stable Low‐Temperature Cycling of Ni‐Rich NCM622 via Interfacial Degradation Suppression

ABSTRACT Ni‐rich layered cathode delivers high capacity and superior energy density. However, it suffers from sluggish ion kinetics and interfacial degradation at low temperatures. Herein, a multifunctional Li 2 O‐B 2 O 3 ‐Li 2 SO 4 (LBLS) composite coating for LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) was designed to simultaneously enhance interface stability and ion transport at low temperatures. The LBLS coating forms a continuous, dense, and ultrathin (3–4 nm) amorphous protective layer on the surface of NCM622 particles, accompanied by gradient B 3+ doping near the surface induced during heat treatment. TOF‐SIMS depth profiling confirms the formation of a thinner and more ionically conductive cathode–electrolyte interphase, with markedly suppressed accumulation of organic fragments (C 2 HO − /C 2 H − ) and inorganic species (LiF − , NiF 2 − , CoF 2 − ). GITT analysis reveals that the coated cathode maintains higher Li + diffusion coefficients throughout extended cycling. DFT and AIMD show Li 2 SO 4 ‐rich phases enable better Li + transport than Li 2 O‐rich phases, with lower barriers and faster MSD growth. The LiNi 0.6 Co 0.2 Mn 0.2 O 2 @Li 2 O‐B 2 O 3 ‐Li 2 SO 4 (NCM@LBLS) cathode exhibits excellent stability at ‐20°C. After 500 cycles at 0.2 C, it still retains 91.14 mAhg −1 , and the capacity retention rate is 70.1%, which is significantly better than NCM622 (48.0%). This work provides an effective surface engineering method for the application of high energy density lithium‐ion batteries in the low temperature field.