State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China.
ACS Appl Mater Interfaces. 2013 Aug 28;5(16):8044-52. doi: 10.1021/am402127u. Epub 2013 Aug 19.
This study reports a simple synthesis of amorphous nickel tungstate (NiWO4) nanostructure and its application as a novel cathode material for supercapacitors. The effect of reaction temperature on the electrochemical properties of the NiWO4 electrode was studied, and results demonstrate that the material synthesized at 70 °C (NiW-70) has shown the highest specific capacitance of 586.2 F g(-1) at 0.5 A g(-1) in a three-electrode system. To achieve a high energy density, a NiW-70//activated carbon asymmetric supercapacitor is successfully assembled by use of NiW-70 and activated carbon as the cathode and anode, respectively, and then, its electrochemical performance is characterized by cyclic voltammetry and galvanostatic charge-discharge measurements. The results show that the assembled asymmetric supercapacitor can be cycled reversibly between 0 and 1.6 V with a high specific capacitance of 71.1 F g(-1) at 0.25 A g(-1), which can deliver a maximum energy density of 25.3 Wh kg(-1) at a power density of 200 W kg(-1). Furthermore, this asymmetric supercapacitor also presented an excellent, long cycle life along with 91.4% specific capacitance being retained after 5000 consecutive times of cycling.
本研究报告了一种简单的无定形氧化镍钨（NiWO4）纳米结构的合成及其作为超级电容器新型阴极材料的应用。研究了反应温度对 NiWO4 电极电化学性能的影响，结果表明，在 70°C 下合成的材料（NiW-70）在三电极系统中以 0.5 A g-1 的电流密度具有最高的比电容 586.2 F g-1。为了获得高能量密度，采用 NiW-70 和活性炭分别作为阴极和阳极，成功组装了 NiW-70//活性炭不对称超级电容器，并通过循环伏安法和恒流充放电测量对其电化学性能进行了表征。结果表明，组装的不对称超级电容器可以在 0 和 1.6 V 之间可逆循环，在 0.25 A g-1 的电流密度下具有 71.1 F g-1 的高比电容，在 200 W kg-1 的功率密度下可以提供最大 25.3 Wh kg-1 的能量密度。此外，该不对称超级电容器还表现出优异的长循环寿命，经过 5000 次连续循环后，比电容保持率为 91.4%。
