3D nitrogen-doped graphene decorated CoNi2S4@polypyrrole electrode for pseudocapacitor with ultrahigh electrochemical performance

In this article, we report a novel hybrid electrode with hierarchical architecture were synthesized via a high-throughput hydrothermal approach under low temperature. The unique hierarchical nanostructured CoNi2S4@PPY/N-3DG (CoNi2S4@PPY hierarchical core/shell network on Nitrogen-doped graphene foam) exhibits significantly promoted electrochemical performance in pseudocapacitor. This hybrid electrode takes advantages of the electrochemical activity of CoNi2S4 and polypyrrole (PPY), hierarchical structure of CoNi2S4@PPY/N-3DG, and synergistic effect originated from CoNi2S4, PPY and N-doped 3DG. These design merits lead to the good ion transportation and electron conductivity, excellent long-cycling galvanostatic charging/discharging stability, and durable high-rate-capacitance of ca. 730 F g (1) at 10 A g (1). Moreover, the flexible, aqueous and solid-state asymmetric supercapacitor (ASC) was successfully fabricated with the CoNi2S4@PPY/N-3DG on Ni foam as cathode and activated carbon (AC) as anode. The electrochemical performance of the ASC device shows the high-energy density of 37.4 W h kg (1) at 1.6 kW kg (1) and the high-power density of 7.2 kW kg (1) at 15.1 W h kg (1), together with an excellent capacitance retention of ca. 82% after 5000 cycles. (C) 2017 Elsevier B.V. All rights reserved.