Facile Preparation and Boosted Electrochemical Properties of Carbon/Carbon Composite Electrodes for Supercapacitors

Herein, a kind of carbon/carbon composite electrode is prepared using polyimide (PI)/3D sphere‐like polyimide composite films as precursors, followed by carbonization. 2,2‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane and 4,4’‐(hexafluoroisopropylidene)diphthalic anhydride are polymerized and thermally imidized to form the matrix, and 3D sphere‐like PI particles synthesized by the solvothermal process are introduced via the in situ polymerization method. The electrochemical behaviors of C/C composites are examined in relation to the loading of the 3D sphere‐like PI crystals and carbonization temperatures. The C/C composite PI/5%3D‐PI‐800 demonstrates a specific capacitance maximum of 322.7 F g −1 at 0.5 A g −1 due to synergistic effects between different types of PIs. The specific capacitance decreases to 214 F g −1 with a retention rate of 66.3% as the current density increases to 10 A g −1 . Moreover, the symmetrical supercapacitor (SC) assembled by PI/5%3D‐PI‐800 shows a specific capacitance of 244.4 F g −1 at 0.5 A g −1 , with a high energy density of 33.94 Wh kg −1 and a power density of 500 W kg −1 . In addition, after 6 months of storage, the button SC is retested and still shows fantastic capacitance retention rate of above 99.5%. Thus, this work proposes a facile method to fabricate the C/C composite electrodes with outstanding electrochemical properties.