Effect Of The Co32-/Co2+/Ni2+ Concentration On The Physicochemical Properties Of Mixed Phase Nano-Ni(Oh)(2)

The mixed phase nanometer Ni(OH)(2) was prepared by ultrasonic-assisted precipitation method using NiCl2, Co(NO3)(2) and Na2CO3 as main materials. The crystal structure, morphology, particle size distribution and electrochemical performance affected by doping ratio, buffer and Ni2+ concentration were characterized. The results indicate that different Co-containing Ni(OH)(2) were co-existence with alpha and beta phase and the proportion of alpha-Ni(OH)(2) significantly increase with the increase of doping ratio. The higher CO32- and Ni2+ concentration is beneficial to form alpha-Ni(OH)(2). The transmission electron microscope (TEM) results show that all samples have the needle-like morphology, the length-diameter ratio decreased with the increase of Na2CO3 and the average particle size was between 60 similar to 90 nm. Composite electrodes were prepared by mixing 8wt% nickel hydroxides with commercial micro-size spherical nickel. The discharge capacities of electrodes increased initially and then decreased with the increase of Na2CO3. When Ni2+ is 0.4 mol.L-1 and Na2CO3 is 0.5 g, the electrode (the Co is 1.02w1%) has the largest discharge capacity, which reaches 306.9 mAh.g(-1) at 0.5C rate, and is 30% higher than that of spherical nickel electrode. The mechanism was investigated to explain the larger discharge capacity, proposing that nanometer alpha-Ni(OH)(2) act as activation center played a catalytic role.