Abstract:Aiming at the shortcomings of traditional graphite negative electrode, such as low specific capacity, large volume expansion of charging, resulting in instability of electrode structure and poor rate performance, it is proposed to use nickel graphene nanosheet (Ni-Gns) composite coating as a cathode electrode material for lithium-ion battery. To verify the performance of this material, a new ultrasonic assisted jet electrodeposition experiment device is developed, and the Ni-Gns composite coating is prepared under different process conditions. Then, the battery negative electrode is fabricated based on such composite materials.. An orthogonal experimental method is employed to measure the discharge capacity of the electrode over 50 charge/discharge cycles, and the electrodeposition process parameters are optimized. The results show that the dominant electrodeposition parameters sequences: added amount of Gns m > coating thickness h > current density D>bath temperature T; optimized process parameters: m = 0.75 g·L-1, h = 30 μm, D = 33 A·dm-2, T= 35 ℃. The surface morphology and microstructure of the optimized coating are observed, which show the Ni -Gns composite coating has a compact structure and a good interface bonding. For transition metal-carbon composite materials, the mechanism model for the electrodeposition process of carbon nanofibers (whiskers) as reinforcement in this composite is proposed. The study suggests that the ultrasonic wave can improve the efficiency of electrodeposition and the structure of the coating. Under the synergistic action of power ultrasonic and electrodeposition, Ni (matrix) and Gns (reinforcing phase) connected by "nickel bridge" between the overlapping form dense and uniform distribution of "percolation conductive network". Combined with Gns's multilayer thin honeycomb lamella structure and its excellent mechanical and electrochemical properties, the material has excellent conductivity and stable structure, and is suitable for lithium ion battery cathode material.