电化学法原位合成Zn/Co-ZIF材料及电容性能

Electrochemical synthesis of Zn/Co-ZIF material and capacitive properties

  • 摘要: 采用电化学法原位合成双金属Zn/Co-类沸石类咪唑骨架材料(ZIF)。通过改变反应溶剂配比、电压大小、反应时间及金属钴盐添加量来探究材料的最佳合成条件。在N,N-二甲基甲酰胺(DMF)与乙醇(EtOH)的体积比为1∶4,外加电压为5 V,外加金属钴盐为0.08 g时,合成不规则层状颗粒结构的Zn/Co-ZIF。以Zn/Co-ZIF为活性物质制备电极用于超级电容器性能研究,并与同条件下电化学法原位合成的ZIF-8作对比。通过循环伏安(CV)、恒电流充放电(GCD)及交流阻抗(EIS)等测试手段探究其电容性能。结果表明,不同扫描速度下Zn/Co-ZIF电极材料的CV曲线有一对氧化还原峰,表现出明显的赝电容特性。在1 A/g的电流密度下,Zn/Co-ZIF电极材料的比电容为189 F/g,高于ZIF-8电极(72 F/g),2000次循环后,比电容值仍能保持初始值的90.5%。

     

    Abstract: In-situ synthesis of bimetallic Zn/Co-zeolitic imidazolate frameworks (ZIF) was successfully achieved by electrochemical method. The optimal synthesis conditions of the Zn/Co-ZIF were explored by changing the reaction solvent ratio, the applied voltage and the amount of metal cobalt salt added. The results show that Zn/Co-ZIF with irregular layered particle structure is obtained under the conditions of the volume ratio of N,N-dimethylformamide (DMF) to ethanol (EtOH) is 1∶4, the applied voltage is 5 V, and the added metal cobalt salt is 0.08 g. The electrode was prepared with Zn/Co-ZIF as the active material for the study of supercapacitor performance, and compared with ZIF-8 synthesized in situ by electrochemical method under the same conditions. Capacitance performance was explored through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The results show that the CV curves of Zn/Co-ZIF electrode materials at different scanning speeds have a pair of redox peaks, which show obvious pseudo-capacitance characteristics. At a current density of 1 A/g, the specific capacitance of the Zn/Co-ZIF electrode material is 189 F/g, which is higher than that of the ZIF-8 electrode (72 F/g). After 2000 cycles, the specific capacitance value is still can maintain 90.5% of the initial value.

     

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