Electrophoretic deposition and hydroplastic foaming synthesis of three-dimensional graphene-based supercapacitor electrodes with high performance and stability

Abstract

Supercapacitors (SC) are electrochemical devices that can store and deliver high power quickly and without degradation after a large number of cycles. Graphene has a wide range of applications in supercapacitors. However, its excellent performance is limited by the stacking of graphene, which reduces the electron/ion transport rate and electrochemical active sites. Three-dimensional graphene can reduce graphene stacking, which not only has more electron/ion transport channels but also increases the specific surface area and provides more electrochemically active sites. Graphene-based supercapacitor electrodes are prepared by a two-step process and do not use any conductive agents or polymeric binders. The first step is to deposit graphene oxide (GO) onto the skeleton of nickel foam (NF) using electrophoretic deposition (EPD) to obtain the precursor GO-NF. The second step is to use the hydroplastic foaming (HPF) method to stretch the graphene sheets to prepare HRGO-NF electrodes. NF provides a stable three-dimensional skeleton and GO can be stabilized on the skeleton by EPD, which improves the stability and structure of the electrode. GO is reduced to RGO by HPF and porous structures are generated between the layers. The layered porous structure effectively provides abundant ion transport channels and considerable electrochemically active sites. The capacitance value is 195 F g− 1 when the current density is 0.5 A/g. When the scan rate is 100 mv/s have 10,000 cycles, the specific capacitance value is maintained at about 98% compared with the initial capacitance, which has good cycling stability. In this work, the simple preparation process of the 3D graphene material constructed has high specific capacitance and high stability, which provides a new idea for the design and preparation of carbon electrode materials for high-performance supercapacitors.