Tungsten Boride Stabilized Single-Crystal LiNi0.83Co0.07Mn0.1O2 Cathode for High Energy Density Lithium-Ion Batteries: Performance and Mechanisms

Abstract

Transition metal doped LiNiO2 layered compounds have attracted significant interest as cathode materials for lithium-ion batteries (LIBs) in recent years due to their high energy density. However, a critical issue of LiNiO2-based cathodes is caused particularly at highly delithiated state by irreversible phase transition, initiation/propagation of cracks, and extensive reactions with electrolyte. Herein, a tungsten boride (WB)-doped single-crystalline LiNi0.83Co0.07Mn0.1O2 (SNCM) cathode is reported that affectively addresses these drawbacks. In situ/ex situ microscopic and spectroscopic evidence that B3+ enters the bulk of the SNCM, enlarging the interlayer spacing, thus facilitating Li+ diffusion, while W3+ forms an amorphous surface layer consisting of LixWyOz (LWO) and LixByOz (LBO), which aids the construction of a robust cathode-electrolyte interphase (CEI) film, are shown. It is also shown that WB doping is effective in controlling the degree of the c-axis contraction and release of oxygen-containing gases at high voltages. The best doping concentration of WB is 0.6 wt.%, at which the capacity retention rate of the SNCM reaches 93.2% after 200 cycles at 2.7–4.3 V, while the morphology and structure of the material remain largely unchanged. The presented modification strategy offers a new way for the design of new stable SNCM cathodes for high-energy-density LIBs.