Architecting versatile NiFe2O4 coating for enhancing structural stability and rate capability of layered Ni-rich cathodes

Nickel-rich layered oxides are considered one of the most promising cathode materials for efficient lithium-ion batteries due to their high energy density and reasonable cost. However, at high cut-off voltage, the interfacial instability and structural degradation lead to severe capacity attenuation and poor thermal stability, which greatly hinder their large-scale applications. Herein, a multifunctional antispinel NiFe2O4 coated LiNi0.6Co0.2Mn0.2O2 (NCM@NFO) material is in-situ induced by co-precipitation and subsequent sintering, boosting the cycling stability of Ni-rich materials. Coupling in-depth characterizations (in-situ X-ray diffraction, etc.) with density functional theory calculations, the versatility of the NFO coating has been revealed. Including suppressing the transition metal dissolution, preventing the unwanted phase transition, inhibiting the oxygen vacancy generation, and stabilizing the crystal structure of the NCM by forming an M-O-N bonding network. More importantly, attributing to the high ion/electron conductivity of the NFO layer, the Li+ transport kinetics between NCM@NFO particles have been facilitated. Benefitting from the collaborative effect of the protective NFO coating, the optimized 2 wt% NFO@NCM (NCM@NFO-2) sample achieves higher capacity retention (81.25 vs 67.88% after 200 cycles) at high voltages (2.75 ∼ 4.5 [email protected]) and more excellent rate capabilities (109.86 vs 49.52 mAh·g−1 at 10C), as well as impressive capacity retention of 81.72% after 100 cycles (at 60 °C@1C). Constructing a versatile bimetallic oxide protective layer at the secondary particle surface of layered oxides provides an effective strategy for Ni-rich cathodes towards high-energy, long-duration, and safe lithium ion batteries.