For several decades, one of the great challenges for constructing a high-energy supercapacitor has been designing electrode materials with high performance. Herein, we report for the first time to our knowledge a novel hybrid supercapacitor composed of battery-type nickel pyrophosphate one-dimensional (1D) nanorods and capacitive-type N-doped reduced graphene oxide as the cathode and anode, respectively, in an aqueous redox-added electrolyte. More importantly, ex situ microscopic images of the nickel pyrophosphate 1D nanorods revealed that the presence of the battery-type redox additive enhanced the charge storage capacity and cycling life as a result of the microstructure stability. The nickel pyrophosphate 1D nanorods exhibited their maximum specific capacitance (8120 mF cm-2 at 5 mV s-1) and energy density (0.22 mWh cm-2 at a power density of 1.375 mW cm-2) in 1 M KOH + 75 mg K3[Fe(CN)6] electrolyte. On the other side, the N-doped reduced graphene oxide delivered an excellent electrochemical performance, demonstrating that it was an appropriate anode. A hybrid supercapacitor showed a high specific capacitance (224 F g-1 at a current density of 1 A g-1) and high energy density (70 Wh kg-1 at a power density of 750 W kg-1), as well as a long cycle life (a Coulombic efficiency of 96% over 5000 cycles), which was a higher performance than most of those in recent reports. Our results suggested that the materials and redox additive in this novel design hold great promise for potential applications in a next-generation hybrid supercapacitor.
Bibliographical noteFunding Information:
This research was partially supported by the Nano.Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future Planning (NRF-2017M3A7B4041987); the Priority Research Centers Program through the National Research Foundation of Korea funded by the Ministry of Education, Science, and Technology (2009-0093823); and a National Research Foundation of Korea (NRF) grant funded by the Korean Government (MSIP) (no. 2015R1A5A1037668).
All Science Journal Classification (ASJC) codes
- Materials Science(all)