Comparative study on flower-like polyimide-based carbon electrodes activated by KOH and HNO3

Abstract

Polyimide (PI)-based flower-like carbon superstructures have recently attracted extensive attention due to their relatively high specific surface area and abundant chemically active sites. However, their practical application for supercapacitor (SC) is still limited by lower specific capacitances. In this study, a kind of PI-based flower-like carbon (PC) materials is firstly prepared by hydrothermal process and further carbonization at 800 °C. Then, the activated PI-based carbon materials (APC) are separately obtained by using chemical activators KOH and HNO3. On the basis of optimizing the activation conditions respectively, the structures and electrochemical performances of the two preferred APC samples are compared. The experimental results show that the APC-1 activated by KOH and APC-2 treated by HNO3 exhibit extremely similar single electrode specific capacitance of 314.7 and 310.3 F g−1 at 0.5 A g−1. After being assembled into symmetrical supercapacitors, the two SC devices display energy densities of 20.28 and 19.54 Wh kg−1 at a power density of 260 W kg−1, respectively. Although the activation method and mechanism are different, the two optimized APCs exhibit similar electrochemical performance. Thus, in this work, we compare the two activation method and prepare a kind of valuable flower-like carbon electrode materials for SCs.