Microstructure Regulation Through W⁶⁺ Doping to Boost Cycling Stability of LiNi_0.9Co_0.1O₂ Ni-Rich Cathode Materials

The applications such as electric vehicles require a high energy density in lithium-ion batteries. LiNi_0.9Co_0.1O₂ has attracted much attention, which has a potential to be next-generation cathode material due to its high specific capacity and reasonable cost. However, some related issues such as Li/Ni mixing, microcracks and surface side reactions caused by H2–H3 phase transformation result in a poor cycling stability for LiNi_0.9Co_0.1O₂. In this paper, the microstructures of LiNi_0.9Co_0.1O₂ by W⁶⁺ doping were regulated by an effective method to adjust the surface energy of the primary particles and transform the disordered and irregular-shape primary particles into the well-ordered radially-aligned elongated shape particles. This microstructure feature can suppress the stress accumulation and the formation of micro-cracks in LiNi_0.9Co_0.1O₂, and provide abundant diffusion channels for Li⁺, thus improving the cycling stability and rate performance of LiNi_0.9Co_0.1O₂ cathode materials. The discharge capacities of 1% (in mole fraction) W-doped LiNi_0.9Co_0.1O₂ are 231.2 mA·h/g at 0.1 C and 213.3 mA·h/g at 0.5 C, respectively, with a high capacity retention of 93% after 150 cycles. This microstructure regulation strategy provides an effective approach for improving the cycling stability of LiNi_0.9Co_0.1O₂ Ni-rich cathode materials.