Hierarchical three dimensional polyaniline/N‐doped graphene nanocomposite hydrogel for energy storage applications

Abstract

AbstractWith the rapid development of portable, lightweight, and flexible electronics, the requirement for advanced energy storage systems has arisen that need to be flexible and cost‐effective with higher power/energy densities. In this context, a two‐step approach has been adopted to develop a binder‐free and flexible supercapacitor electrode on carbon cloth based on hierarchical three dimensional (3D) conducting polymer hydrogels. Firstly, nitrogen‐doped graphene (NGN) was synthesized using urea as a reducing as well as a doping agent. Subsequently, polyaniline (PAni) hydrogel has been grown on NGN nanosheets via insitu oxidative polymerization in the vicinity of carbon cloth and further utilized as an electrode for electrochemical measurements. Here, phytic acid was used as a gelatinizer and as a dopant resulting in the formation of a cross‐linked hydrogel structure. The direct deposition of PAni/NGN nanocomposite on carbon cloth strengthens the juncture involving the carbon cloth and electrode material, resulting in enhanced electron transmission. The 3D hydrogel architecture ascertains robust contact between electrolyte and electrode for an efficient charge storage system. For a two‐electrode symmetric arrangement, at 1 A/g, PAni/NGN nanocomposite hydrogel displayed a maximum specific capacitance of 808.7 F/g due to the pseudocapacitive reaction on/near the accessible surface area, as well as an outstanding rate capability and cyclic performance due to electric double layer capacitance (EDLC). The supercapacitor cell delivered maximum specific power and specific energy value of 0.44 kW/kg and 13.63 Wh/kg, respectively. Thus, the composite hydrogel has the benefit of being able to be utilized directly as binder‐free supercapacitor electrodes, leading to viable choice for high‐performance and cost‐effective energy storage devices.