Improvement of electrochemical performance of LiNi0.8Co0.1Mn0.1O2 cathode material via Li2.09W0.9Nb0.1O4 Li-ion conductive coating layer

Recently, niobium tungsten oxide has garnered considerable attention owing to its excellent Li-ion diffusion rate and prominent structural stability during charge–discharge cycles. Here, a cathode material (LiNi 0.8 Co 0.1 Mn 0.1 O 2 , NCM811) for Li-ion batteries is successfully coated with Li-ion conductive Li 2.09 W 0.9 Nb 0.1 O 4 using a simple wet-chemical coating method followed by high-temperature sintering. A physicochemical phase analysis reveals that a 4–5-nm-thick coating with a Li 2.09 W 0.9 Nb 0.1 O 4 crystal structure is evenly distributed on the surface of the cathode particles. Among cathodes coated with different amounts of material, the one coated with 0.5 wt% Li 2.09 W 0.9 Nb 0.1 O 4 yielded the best overall performance, with a high discharge capacity of 136.8 mAh g −1 at 10 C and long-term cycling stability with a capacity retention of 91.7% after 100 cycles at 1 C. This excellent electrochemical performance can be attributed to the coating’s ability to prevent the impedance from increasing and the Li-ion diffusion coefficient from decaying. In addition, it protects the cathode from side reactions and stabilizes the structure during cycling.