Synthesis of Capsule-like Porous Hollow Nanonickel Cobalt Sulfides via Cation Exchange Based on the Kirkendall Effect for High-Performance Supercapacitors

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• 作者：Yongfu Tang ; Shunji Chen ; Shichun Mu ; Teng Chen ; Yuqing Qiao ; Shengxue Yu ; Faming Gao
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：April 20, 2016
• 年：2016
• 卷：8
• 期：15
• 页码：9721-9732
• 全文大小：938K
• 年卷期：0
• ISSN：1944-8252

文摘

To construct a suitable three-dimensional structure for ionic transport on the surface of the active materials for a supercapacitor, porous hollow nickel cobalt sulfides are successfully synthesized via a facile and efficient cation-exchange reaction in a hydrothermal process involving the Kirkendall effect with γ-MnS nanorods as a sacrificial template. The formation mechanism of the hollow nickel cobalt sulfides is carefully illustrated via the tuning reaction time and reaction temperature during the cation-exchange process. Due to the ingenious porous hollow structure that offers a high surface area for electrochemical reaction and suitable paths for ionic transport, porous hollow nickel cobalt sulfide electrodes exhibit high electrochemical performance. The Ni_1.77Co_1.23S₄ electrode delivers a high specific capacity of 224.5 mAh g^–1 at a current density of 0.25 A g^–1 and a high capacity retention of 87.0% at 10 A g^–1. An all-solid-state asymmetric supercapacitor, assembled with a Ni_1.77Co_1.23S₄ electrode as the positive electrode and a homemade activated carbon electrode as the negative electrode (denoted as NCS//HMC), exhibits a high energy density of 42.7 Wh kg^–1 at a power density of 190.8 W kg^–1 and even 29.4 Wh kg^–1 at 3.6 kW kg^–1. The fully charged as-prepared asymmetric supercapacitor can light up a light emitting diode (LED) indicator for more than 1 h, indicating promising practical applications of the hollow nickel cobalt sulfides and the NCS//HMC asymmetric supercapacitor.