Polypyrrole shell@3D-Ni metal core structured electrodes for high-performance supercapacitors

Abstract

Three-dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high-performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D-Ni-core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as-prepared material exhibits a high specific capacitance (726 F g⁻¹ at a charge/discharge rate of 1 A g⁻¹), good rate capability (a decay of 33 % in Csp with charge/discharge rates increasing from 1 to 20 A g⁻¹), and high cycle stability (only a small decrease of 4.2 % in Csp after 1000 cycles at a scan rate of 100 mV s⁻¹. Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as-prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg⁻¹) and superior long-term cycle ability (only 4.4 % and 18.6 % loss in Csp after 2000 and 5000 cycles, respectively).