Enhancing the Integral Structural and Thermal Stability of Ultrahigh-Ni Cathodes via Morphology Refinement and In Situ Interfacial Engineering

Nickel-rich layered oxides are promising cathodes incommercialmaterials for lithium-ion batteries. However, the increase of thenickel content leads to the decay of cyclic performance and thermalstability. Herein, in situ surface-fluorinated W-doping LiNi0.90Co0.05Mn0.05O2 cathodes enhanceintegral lithium-ion migration (transfer in bulk and diffusion inthe interface) kinetics by synergistically solving the problems ofbulk and interface structural degradation. Owing to the introductionof tungsten, the growth of primary particles is regulated toward the(003) crystal plane and with the acicular structure, which furtherstabilizes the bulk structure during cycling. Moreover, the LiF coatinglayer on the cathode/electrolyte interface physically isolates theattack of the electrolyte on the surface cathodes and acceleratesthe lithium-ion diffusion rate, ultimately ameliorating the interfacialdynamics and structural stability. Dual-modified LiNi0.90Co0.05Mn0.05O2 exhibits superiorelectrochemical properties, especially more remarkable cyclic retention(88.16% vs 70.44%) after 100 cycles at 1 C and more outstanding highcurrent rate properties (173.31 mAh & BULL;g(-1) vs135.97 mAh & BULL;g(-1)) at 5 C than the pristine one.This work emphasizes the probability of an integrated optimizationstrategy for Ni-rich materials, which provides an innovative ideafor ameliorating (bulk and interfacial) structure degradation andpromoting the diffusion of lithium ions during cycling.