| MH / Ni battery was considered as"Green Battery"because it has notable advantages as high specific capacity, easy to be recharged, no memory effect, low pollution and long cycle life. Nickel hydroxide is the main material of its positive electrode.Nanoβ-Ni(OH)2 doped with cobalt and nanoα-Ni(OH)2 doped with aluminum were prepared by co-precipitation method. Effects of doping amount and the dispersant type on the material's physicochemical and electrochemical properties were investigated. The nano-materials were characterized by means of atomic absorption, UV-visible spectrophotometry, IR absorption, X-ray diffraction, transmission electron microscopy etc. Using voltammetry, chronoamperometry and electrochemical impedance spectroscopy testing methods, the influence of cobalt and aluminum doping volume on electrochemical and discharge performance was studied. The charge/discharge performance and the cycle life of the multiplex Ni(OH)2 electrode and the pure Ni(OH)2 electrode in an open cell system were inspected.The results showed that theoretical doping volumn could replace the actual content of Co or Al when the amount was minor,β-Ni(OH)2 orα-Ni(OH)2 were obtained while the dopant was Co or Al. It's very hard to wipe off the dispersant in the washing process. More and more H2O and anions entered the crystal lattice while the Al doping volumn increased. TEM results showed that the grain has sheet and granular shape when using Co as dopant and the needle shape was obtained while using Al dopant.Contrasting to micro-spherical Ni(OH)2, the reversibility became better when Co was doped, and it would become worse when Al was doped; however, when Co and Al were both doped, the reversibility improved again. The biggest proton diffusion coefficient reached 4.294×10-10 cm2·s-1 while the doping amount of Co was 5 mass%.Electrochemical impedance spectroscopy test results showed that the Rr of the open cell made the sample doped with 5 mass% Co was smaller sharply than that of the one made by the sample doped with 5 mass% Al. Electrochemical reaction resistance decreased obviously after activation. The surface of the reunion particles was oxidized first, the interior of the granule began to be oxidized when SOC=80%.The discharge platform of Co doped multiplex nano Ni(OH)2 battery was higher than that of micro spherical Ni(OH)2 battery. The discharge performance increased as the c value increased or the cystallinity on (101) decreased. When the amont of Co was 5 mass%, the 0.2 C dischargecapacity reached 271 mAh·g-1, increased by 7% and 11% compared with the non-doped sample and the micro spherical Ni(OH)2 sample. Nevertheless, Al doping contributed nothing to the capacity, the more was the doping volumn, the less was the capacity. The discharge platform improved and the capacity decreased while Co and Al was doped simultaneously instead of doing Al only. The discharge capacities of all the samples in 1 C rate were reduced. Tween 80 was superior to other dispersants considering the discgarge capacity.The capacity of each multiplex nano Ni(OH)2 open cell reduced gradually in the first 20 cycles, and it increased slowly later, and then decreased gradually again after 80 cycles. The 0.2 C discharge capacity of the doping Co 5 mass% sample reached 274.3 mAh·g-1 in the 81st cycle. Conparing to multiplex nano Ni(OH)2 open cell, the capacity pure nano Ni(OH)2 open cell pyramided in the first 10 cycles. After the first 10 cycles, the capacity of open cells made byβ-Ni(OH)2 reduced slowly, while the capacity kept stable made byα-Ni(OH)2, However, the capacity of all the saples fell down hastily after 60 cycles.
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