Ning Jinfeng, Zhang Tianyu, He Ying, Jia Congpu, Saha Petr, Cheng Qilin
Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China.
Centre of Polymer Systems, Tomas Bata University in Zlin, nam. T. G. Masaryka 5555, Zlin 760 01, Czech Republic.
Materials (Basel). 2017 Jun 1;10(6):608. doi: 10.3390/ma10060608.
In this work, a two-step electrodeposition strategy is developed for the synthesis of core-shell Co₃O₄@CoS nanosheet arrays on carbon cloth (CC) for supercapacitor applications. Porous Co₃O₄ nanosheet arrays are first directly grown on CC by electrodeposition, followed by the coating of a thin layer of CoS on the surface of Co₃O₄ nanosheets via the secondary electrodeposition. The morphology control of the ternary composites can be easily achieved by altering the number of cyclic voltammetry (CV) cycles of CoS deposition. Electrochemical performance of the composite electrodes was evaluated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques. The results demonstrate that the Co₃O₄@CoS/CC with 4 CV cycles of CoS deposition possesses the largest specific capacitance 887.5 F·g at a scan rate of 10 mV·s (764.2 F·g at a current density of 1.0 A·g), and excellent cycling stability (78.1% capacitance retention) at high current density of 5.0 A·g after 5000 cycles. The porous nanostructures on CC not only provide large accessible surface area for fast ions diffusion, electron transport and efficient utilization of active CoS and Co₃O₄, but also reduce the internal resistance of electrodes, which leads to superior electrochemical performance of Co₃O₄@CoS/CC composite at 4 cycles of CoS deposition.
在这项工作中，开发了一种两步电沉积策略，用于在碳布（CC）上合成核壳结构的Co₃O₄@CoS纳米片阵列，用于超级电容器应用。首先通过电沉积在CC上直接生长多孔Co₃O₄纳米片阵列，然后通过二次电沉积在Co₃O₄纳米片表面包覆一层薄薄的CoS。通过改变CoS沉积的循环伏安（CV）循环次数，可以轻松实现三元复合材料的形貌控制。采用循环伏安法、恒电流充放电法和电化学阻抗谱技术对复合电极的电化学性能进行了评估。结果表明，CoS沉积4个CV循环的Co₃O₄@CoS/CC在扫描速率为10 mV·s⁻¹时具有最大比电容887.5 F·g⁻¹（在电流密度为1.0 A·g⁻¹时为764.2 F·g⁻¹），并且在5000次循环后，在5.0 A·g⁻¹的高电流密度下具有优异的循环稳定性（电容保持率为78.1%）。CC上的多孔纳米结构不仅为快速离子扩散、电子传输以及活性CoS和Co₃O₄的有效利用提供了大的可及表面积，还降低了电极的内阻，这使得Co₃O₄@CoS/CC复合材料在CoS沉积4个循环时具有优异的电化学性能。
