Fabrication and characterization of graphene coated nickel electrodes with internally stacked double layer supercapacitors

Abstract

Supercapacitors are getting a lot of attention as high-performance energy storage devices that can find applications in multiple fields including high-power military devices and wearable or portable electronics. For a better supercapacitor device electrode plays a vital role and graphene is being widely studied as an efficient material for electrodes due to its large specific surface area of 2630 m2/g. However, the disordered alignment and the severe aggregation hinder the maximum utilization of its surface area. In this work nickel nitrate and chloroform treatments were used to improve the deposition of graphene on the current collector and to improve the substrate surface quality, respectively. In addition, the stacking technique is used to improve the overall energy storage capability of the device. The electrophoretic deposition (EPD) coating method was used to deposit graphene on the current collector. The important optimization was also performed in a KOH-based 3-electrode system and the chloroform treated and graphene-coated electrode showed an improved capacitance of 151 F/g at scan rate 0.01 V/sec as compared to the 126 F/g of the untreated sample. The graphene-coated electrode showed good cyclic stability with capacitance fading of ∼4.4 × 10−6%/cycle and a higher operating voltage up to 6 V has been achieved by utilizing the stacking method.

Keywords

• Electrochemical double layer capacitors
• Graphene
• Stacked-configurations
• Electrophoretic deposition