Electrochemical properties of free-standing polypyrrole/graphene oxide/zinc oxide flexible supercapacitor

We report the preparation of a polypyrrole/graphene oxide/zinc oxide nanocomposite on a nickel foam using a simple and rapid single-step electrochemical deposition process under ambient conditions. A free-standing flexible supercapacitor was fabricated by sandwiching a polyvinyl alcohol hydrogel polymer electrolyte between two layers of the as-prepared ternary nanocomposite electrodes. The electrochemical properties of the free-standing supercapacitor were analyzed using a two-electrode system. The supercapacitor achieved a specific capacitance of 123.8F/g at 1A/g, which was greater than its single (39.1F/g) and binary (81.3F/g) counterparts. This suggests that ZnO acts as a spacer and support that hinders the ternary structure from collapsing and subsequently enhances the diffusion of ions within the matrix. The flexible supercapacitor exhibited remarkable electrochemical stability when subjected to bending at various angles. The cycling stability of the ternary nanocomposite showed a favorable specific capacitance retention of more than 90% after 1000cycles for mild alkaline electrolytes compared with strong alkali electrolytes. The presence of glycerin in the polymer electrolyte enabled the supercapacitor to perform better under the vigorous cycling condition. The potential of the as-fabricated supercapacitor for real applications was manifested by its ability to light up a light-emitting diode after being charged. Copyright (c) 2014 John Wiley & Sons, Ltd.