Sun Chao, Sun Li, Fan Kaifeng, Shi Yan, Gu Jialin, Lin Yifan, Hu Jingjing, Zhang Yihe
Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing, 100083, PR China.
Dalton Trans. 2021 Jul 6;50(26):9283-9292. doi: 10.1039/d1dt01217g.
Co9S8 and transition metal hydroxides are both potential pseudo-capacitance electrode materials for supercapacitors. Co9S8 has a large specific capacitance and electrochemical activity, and transition metal hydroxides have the advantages of high capacitance and redox activity due to their multiple valence metals and open layered structure. In this study, Co9S8 and NiCoLDH are used to form a Co9S8-aCNT-NiCoLDH composite electrode material by twining acidified carbon nanotubes (aCNTs) around hollow Co9S8 rods and then compounding nickel cobalt hydroxide (NiCoLDH) on the outside. aCNTs provide more electronic channels, which bring more active electrochemical reactions and absorb the volume expansion of Co9S8. The hollow Co9S8 rods and flower-like NiCoLDH structures ensure that the electrode has a highly open structure, which increases the contact area with the electrolyte and is beneficial for ion transport. The outer NiCoLDH can also reduce the volume expansion of Co9S8. These advantages ensure the high specific capacitance and rate performance of the Co9S8-aCNT-NiCoLDH electrode material. Co9S8-aCNT-NiCoLDH was used as the positive material to fabricate asymmetric supercapacitors with attractive energy density and power density, which further proved its excellent electrochemical performance.
Co9S8和过渡金属氢氧化物都是超级电容器潜在的赝电容电极材料。Co9S8具有较大的比电容和电化学活性，而过渡金属氢氧化物由于其多价金属和开放的层状结构，具有高电容和氧化还原活性的优点。在本研究中，通过将酸化碳纳米管（aCNTs）缠绕在中空的Co9S8棒周围，然后在外部复合镍钴氢氧化物（NiCoLDH），使Co9S8和NiCoLDH形成Co9S8-aCNT-NiCoLDH复合电极材料。aCNTs提供了更多的电子通道，带来更多的活性电化学反应并吸收Co9S8的体积膨胀。中空的Co9S8棒和花状的NiCoLDH结构确保电极具有高度开放的结构，增加了与电解质的接触面积，有利于离子传输。外部的NiCoLDH也可以减少Co9S8的体积膨胀。这些优点确保了Co9S8-aCNT-NiCoLDH电极材料具有高比电容和倍率性能。Co9S8-aCNT-NiCoLDH被用作正极材料来制备具有吸引人的能量密度和功率密度的不对称超级电容器，这进一步证明了其优异的电化学性能。
