WO3 coating improves the cyclic stability of LiNi0.9Co0.05Mn0.05 as cathode materials for lithium-ion batteries.

In this paper, WO 3 uniformly coated LiNi 0.9 Co 0.05 Mn 0.05 O 2 cathode materials are prepared by wet coating method using ammonium metatungstate as tungsten source. The XRD, SEM, and XPS tests show that the cladding process introduced W ions into the NCM lattice, increasing the layer spacing and improving the lithium diffusion rate. The charge/discharge test results indicate that a moderate amount of WO 3 coating can enhance the rate-discharge performance and increase the long cycle life. After 100 cycles at 1C (180 mAh g−1), the reversible capacity of the material containing 0.5wt% WO 3 coating is 157.9 mAh g−1, while that of the original material is only 130.9 mAh g−1, which indicates that the WO 3 coating protects the cathode material from HF corrosion, thus improving the stability of the structure. DFT calculations show that the dangling bonds of O on the NCM surface are highly susceptible to binding with W, which reduces the possibility of WO 3 coating exfoliation.WO 3 and NCM are p-type semiconductors and semi-metallic materials, respectively, which form ohmic contacts at heterogeneous interfaces thereby increasing the electronic conductivity of the materials, and due to the synergistic effect, the diffusion barrier of Li near the heterogeneous interfaces is lower than that of the pristine materials. [ABSTRACT FROM AUTHOR]