Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.
ACS Nano. 2013 May 28;7(5):4042-9. doi: 10.1021/nn4000836. Epub 2013 Apr 11.
Flexible solid-state supercapacitors are of considerable interest as mobile power supply for future flexible electronics. Graphene or carbon nanotubes based thin films have been used to fabricate flexible solid-state supercapacitors with high gravimetric specific capacitances (80-200 F/g), but usually with a rather low overall or areal specific capacitance (3-50 mF/cm(2)) due to the ultrasmall electrode thickness (typically a few micrometers) and ultralow mass loading, which is not desirable for practical applications. Here we report the exploration of a three-dimensional (3D) graphene hydrogel for the fabrication of high-performance solid-state flexible supercapacitors. With a highly interconnected 3D network structure, graphene hydrogel exhibits exceptional electrical conductivity and mechanical robustness to make it an excellent material for flexible energy storage devices. Our studies demonstrate that flexible supercapacitors with a 120 μm thick graphene hydrogel thin film can exhibit excellent capacitive characteristics, including a high gravimetric specific capacitance of 186 F/g (up to 196 F/g for a 42 μm thick electrode), an unprecedented areal specific capacitance of 372 mF/cm(2) (up to 402 mF/cm(2) for a 185 μm thick electrode), low leakage current (10.6 μA), excellent cycling stability, and extraordinary mechanical flexibility. This study demonstrates the exciting potential of 3D graphene macrostructures for high-performance flexible energy storage devices.
柔性固态超级电容器作为未来柔性电子产品的移动电源具有很大的吸引力。基于石墨烯或碳纳米管的薄膜已被用于制造具有高重量比电容（80-200 F/g）的柔性固态超级电容器，但由于电极厚度非常小（通常为数微米）和质量负载非常低，通常整体或面比电容（3-50 mF/cm(2)）较低，这对于实际应用来说是不理想的。在这里，我们报告了一种三维（3D）石墨烯水凝胶在制备高性能固态柔性超级电容器方面的探索。由于具有高度互联的 3D 网络结构，石墨烯水凝胶具有出色的导电性和机械强度，使其成为柔性储能器件的理想材料。我们的研究表明，具有 120 μm 厚石墨烯水凝胶薄膜的柔性超级电容器可以表现出优异的电容特性，包括 186 F/g 的高重量比电容（对于 42 μm 厚的电极，可达 196 F/g）、前所未有的面比电容 372 mF/cm(2)（对于 185 μm 厚的电极，可达 402 mF/cm(2)）、低泄漏电流（10.6 μA）、优异的循环稳定性和出色的机械灵活性。本研究展示了 3D 石墨烯宏观结构在高性能柔性储能器件中的令人兴奋的潜力。
