Facile activation of flower-like polyimide-based carbon electrodes for high-performance supercapacitors

In this work, the flower-like polyimide (PI) particles were prepared via a solvothermal method using poly(amic acid) (PAA) solution derived from 4,4′-oxydianiline (ODA) and cyclobutane-1,2,3,4-tetracarboxylicdianhydride (CBDA). Then, the corresponding carbon materials were obtained by further pyrolysis. The effects of the concentration of PAA solution and carbonization temperature on the properties of carbon materials were investigated. Moreover, in order to increase the electrochemical performance, the flower-like carbon particles were further activated by KOH, and the amount of KOH was optimized. The structures and properties of the final flower-like carbon particles were characterized by FTIR, SEM, XPS, XRD, Raman, nitrogen adsorption-desorption and electrochemical tests. When the mass ratio of carbon materials to KOH was 1:3, the activated flower-like carbon particles A-PI ODA -1/3 showed a high specific surface area of 1498 m 2 g −1 , a specific capacitance of 313.4 F g −1 at 0.5 A g −1 and a high-rate capability of 230.0 F g −1 at 10 A g −1 . The assembled symmetrical supercapacitor (SC) showed a maximum energy density of 28.08 Wh kg −1 , coupled with a power density of 500.0 W kg −1 . After 20,000 cycles at a current density of 1 A g −1 , the SC exhibited an excellent cycling stability with a 99.6 % capacitance retention rate. Therefore, the activated flower-like carbon particles can be simply prepared, which could be expected to be used as a preferable electrode material for energy storage applications. • The flower-like polyimide particles were prepared via solvothermal method. • The carbon microflowers activated by KOH showed rich porous structure, large surface area and high specific capacitances. • The assembled supercapacitors exhibited excellent electrochemical properties.