A comparative study of bulk and surface W-doped high-Ni cathode materials for lithium-ion batteries†

Abstract

This study explores the influence of tungsten (W) doping on the structural and electrochemical performance of high-nickel LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode materials, aiming to enhance lithium-ion battery high rate and long-term cycling stability. Tungsten was incorporated through two distinct approaches: bulk doping via a wet-chemical co-precipitation method and surface doping via solid-state processing during calcination. Comprehensive characterization, including X-ray diffraction, scanning electron microscopy, and micro-cavity electrode electrochemical measurements was conducted to elucidate the effect of W doping on the morphology, crystallinity, and lithium-ion transport properties. Results indicate that W doping enhances charge transfer kinetics and stabilizes the NCM811 microstructure, effectively reducing capacity fade. Notably, surface-doped samples (s-LNCMW) demonstrated superior cycling stability, with 92% capacity retention after 500 cycles, attributed to the formation of a protective Li_xWO_y layer. This study provides insights into the optimization of doped NCM cathodes, underscoring the potential of surface tungsten doping as a strategic approach for developing high-energy-density cathodes with improved cycle life for next-generation lithium-ion batteries.