摘要
This work demonstrates a new synthesis method for NCM powder and surface modification at the same time. Cobalt manganese oxyhydroxide forms uniform precipitation on the surface of Ni(OH) 2 through redox reaction. KMnO 4 is used as a strong oxidant and the source of manganese. This is different from the conventional process that metal ions in the precursors have the same valence state as products. A slight amount of Ni 2+ is oxidized to Ni 3+ on the surface of Ni(OH) 2 . This surface oxidation process is proved to enhance the structural stability and the rate capacity of Ni-rich cathode materials. The reaction takes place spontaneously under a mild condition. The impurity-free LiNi 0.96 Co 0.03 Mn 0.01 O 2 (NMC-R) with high crystallinity is successfully fabricated. Uniform distribution of elements is formed after calcination. NMC-R exhibits low cation mixing degree and order surface structure. The material synthesized by redox-assisted deposition displays a high capacity of ~197 mAh g − 1 at the beginning and the capacity retention is about 93% after 100 cycles. It also provides 68 mAh g − 1 higher than the LiNiO 2 sample at a high rate of 10C. In summary, a novel solvent-based preparation method for cathode material with a stable structure is developed, which is very promising for practical industrial scale.