School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457.
ACS Appl Mater Interfaces. 2012 May;4(5):2801-10. doi: 10.1021/am300455d. Epub 2012 May 4.
We have successfully fabricated an asymmetric supercapacitor with high energy and power densities using graphene hydrogel (GH) with 3D interconnected pores as the negative electrode and vertically aligned MnO(2) nanoplates on nickel foam (MnO(2)-NF) as the positive electrode in a neutral aqueous Na(2)SO(4) electrolyte. Because of the desirable porous structure, high specific capacitance and rate capability of GH and MnO(2)-NF, complementary potential window of the two electrodes, and the elimination of polymer binders and conducting additives, the asymmetric supercapacitor can be cycled reversibly in a wide potential window of 0-2.0 V and exhibits an energy density of 23.2 Wh kg(-1) with a power density of 1.0 kW kg(-1). Energy density of the asymmetric supercapacitor is significantly improved in comparison with those of symmetric supercapacitors based on GH (5.5 Wh kg(-1)) and MnO(2)-NF (6.7 Wh kg(-1)). Even at a high power density of 10.0 kW kg(-1), the asymmetric supercapacitor can deliver a high energy density of 14.9 Wh kg(-1). The asymmetric supercapacitor also presents stable cycling performance with 83.4% capacitance retention after 5000 cycles.
我们成功地制造了一种具有高能量和功率密度的不对称超级电容器，该超级电容器的负极为具有 3D 相互连通孔的石墨烯水凝胶（GH），正极为垂直排列在泡沫镍上的 MnO2 纳米板（MnO2-NF），在中性水溶液 Na2SO4 电解质中使用。由于 GH 和 MnO2-NF 的理想多孔结构、高比电容和倍率性能、两个电极的互补电位窗口以及消除了聚合物粘结剂和导电添加剂，因此不对称超级电容器可以在 0-2.0 V 的宽电位窗口内可逆循环，并具有 23.2 Wh kg-1 的能量密度和 1.0 kW kg-1 的功率密度。与基于 GH（5.5 Wh kg-1）和 MnO2-NF（6.7 Wh kg-1）的对称超级电容器相比，不对称超级电容器的能量密度有了显著提高。即使在 10.0 kW kg-1 的高功率密度下，不对称超级电容器也可以提供 14.9 Wh kg-1 的高能量密度。不对称超级电容器还具有稳定的循环性能，在 5000 次循环后电容保持率为 83.4%。
