W-Doped LiNi1/3Co1/3Mn1/3O2 with Excellent High-Rate Performance Synthesized via Hydrothermal Lithiation

Abstract

High energy consumption and excess lithium are required for the preparation of transition metal layered oxide cathodes through high-temperature solid-phase sintering. Exploring new low-cost preparation methods can raise the cost competitiveness of commercial lithium-ion batteries. Herein, nanoscale LiNi1/3Co1/3Mn1/3O2(NCM111) was prepared via a hydrothermal lithiation process from transition metal sulfates. The dissolution-recrystallization mechanism during the low-temperature hydrothermal process enables the formation of nanoparticles. The nanoscale particle size shortens the diffusion channel of lithium ions, which can significantly boost the rate-performance of NCM111. The high concentration of Li+ in the solution hinders Ni2+ from occupying the 3a site of Li+ during the formation of the layered structure, inhibiting the cation mixing, and the unreacted lithium in the solution can be easily recycled. The conductivity of the material is improved by introducing the high valence ion W6+, while the strong W–O bond stabilizes the layered structure and further restrains cation mixing. The results show that the W-doped NCM111 has a specific capacity of 131.9 mAh g−1 at an ultra-high discharge rate of 20 C (3200 mA g−1).