Spray pyrolysis feasibility of tungsten substitution for cobalt in nickel-rich cathode materials

Cobalt plays an indispensable role in stabilizing the lattice structure of high-capacity Ni-rich cathode materials. However, the extravagant price and toxicity still limit its development. Generally, it is feasible for the use of transition metal substitution to reduce the Co content. Whereas the conventional co-precipitation method could not meet the requirements of multi-element co-precipitation and uniform distribution of elements due to the differences between element concentration and deposition rate. Herein, spray pyrolysis is introduced to prepare LiNi_0.9Co_0.1-xW_xO₂ (LNCW). Particularly, the pyrolysis behavior of ammonium metatungstate is studied together with the W substitution for Co. With the feasibility of spray pyrolysis, the Ni-Co-W contained oxide precursor shows a homogeneous distribution of metal elements, which is beneficial to uniform substituting of W in the final materials. It is found that with W substitution, the size of primary particles shows a decreasing trend from 338.06 nm to 71.76 nm and the cation disordering is low to 3.34%. As a result, the prepared LNCW shows significantly improved electrochemical performance. In the optimal conditions, the lithium-ion battery assembled with the LiNi_0.9Co_0.025W_0.075O₂ (LNCW-0.75%) sample exhibits enhanced capacity retention of 82.7% after 200 cycles, which provides insight into the development of Ni-rich and low-cobalt materials. The results show that W can compensate for the loss caused by Co deficiency to a certain extent.