Capacitive performance and cycling stability of NixCo1-x(OH)2 xerogels |
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| Authors: | CHENG Jie LIU Hanmin WEN Yuehua CAO Gaoping |
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| Affiliation: | 1 Research Institute of Chemical Defense, Beijing 100191, China;
2 Zhangjiakou Wind & Solar Power Energy Demonstration Station Co., Ltd. State Grid, Zhangjiakou 075000, Hebei, China |
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| Abstract: | NixCo1-x(OH)2 xerogels were formed by sol-gel method under ambient pressure. The structure of these materials was characterized using N2 (77 K) adsorption, XPS and XRD. Their capacitive performance was evaluated by using galvanostatic technique. The results show that the NixCo1-x(OH)2 xerogels materials have a well-developed mesopore structure. The rate performance of the NixCo1-x(OH)2 xerogels materials was greatly improved by Co impregnate, and the optimal amount of Co was 24%. The crystal structure of NixCo1-x(OH)2 xerogels is the same as that of the β-Ni(OH)2. The crystallite size of the NixCo1-x(OH)2 xerogels will change largely except the amount of Co is above 20%. The electrochemical capacitor consisted with activated carbon and Ni0.76Co0.24(OH)2 was cycled at a current density of 20 mA/cm2, a coulombic efficiency above 95% and above 90% capacity retention after 100000 cycles were obtained. In the process long charge/discharge cycle, the crystallite size of the Ni0.76Co0.24(OH)2 xerogels changes little, but the lattice parameter of the Co0.24Ni0.76(OH)2 xerogels gradually shifts to the lattice parameters of the ideal β-Ni(OH)2 crystal. |
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| Keywords: | xerogel NixCo1-x(OH)2 xerogels electrochemical capacitor galvanostatic technique |
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