Flower-like nickel-cobalt hydroxides converted from phosphites for high rate performance hybrid supercapacitor electrode materials
Flower-like nickel-cobalt hydroxides converted from phosphites for high rate performance hybrid supercapacitor electrode materials
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DOI：
10.1016/j.electacta.2016.05.213
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发表时间：
2016-08-20
影响因子：
6.6
通讯作者：
Liu, Chenguang
中科院分区：
文献类型：
--
作者：
Gou, Jianxia;Xie, Shengli;Liu, Chenguang
Ni-Co氢氧化物作为混合超级电容器的电极材料已被广泛研究。在这项工作中，我们报告了一种有效的方法来显着提高镍钴氢氧化物的倍率性能，通过工程的双通道结构和调整钴的价态，这是通过一个简单的在适合的化学处理亚磷酸盐实现。在20 A g（-1）时，得到的花状Ni-Co氢氧化物电极的比电容为1425 F g（-1），是1 A g（-1）时1698 F g（-1）的83.9%。在10A·g ~（-1）电流密度下循环4000次后，其效率为80.6%。此外，在组装的水性不对称超级电容器中，使用Ni-Co氢氧化物作为正极材料和活性炭作为负极材料，在801.2W kg（-1）的功率密度下实现了40.1Wh kg（-1）的能量密度。我们的研究表明，化学处理引起形态和相变，并诱导部分Co-2转化为更导电的Co 3+状态。而其电化学性能与钴的微观结构和价态有着密切的关系。(C)2016爱思唯尔有限公司版权所有
Ni-Co hydroxides have been extensively studied as electrode materials for hybrid supercapacitors. In this work, we report an effective method to significantly improve the rate performance of Ni-Co hydroxides through engineering the dual-channel structure and tuning the valence state of Cobalt, which is realized through a facile in suit chemical treatment of phosphites. The specific capacitance of the obtained flower-like Ni-Co hydroxide electrode is 1425 F g(-1) at 20 A g(-1), which is 83.9% of 1698 F g(-1) at 1 A g(-1). Simultaneously, a moderate cycling stability with an efficiency of 80.6% after cycling 4000 times at a current density of 10 A g(-1) is obtained. Moreover, an energy density of 40.1 Wh kg(-1) at a power density of 801.2 W kg(-1) has been achieved in an assembled aqueous asymmetric supercapacitor, using Ni-Co hydroxide as positive electrode material and activated carbon as negative electrode material. Our study shows that the chemical treatment evokes morphology and phase transformation and induces partial Co-2 conversion to a more conductive Co3+ state. And the electrochemical performance has a significant relationship with the microstructure and valence state of Cobalt. (C) 2016 Elsevier Ltd. All rights reserved.