Hierarchical flaky porous carbon derived from waste polyimide film for high-performance aqueous supercapacitor electrodes

The development of electric vehicles is increasing the demand for supercapacitors, for which carbon materials can make excellent electrodes. In this study, waste scraps of polyimide (PI) film were used to fabricate several flaky porous carbon materials for use as supercapacitor electrodes. The pore structure and functional groups of the porous carbons were tailored by KOH activation. The relationships between pore structure, the carbon matrix, functional groups, and electrochemical performance were investigated via N-2 adsorption, XRD, Raman spectroscopy, FT-IR, XPS, and electrochemical measurements. The flaky porous carbon materials have a graded distribution of hierarchical pore structures and are rich in O/N functional groups. They have an outstanding capacitance retention rate and a high specific capacitance of 482 F g(-1), which is higher than those of PI film-based porous carbons prepared by physical activation and of commercial activated carbon electrodes. Their flaky structure endows them with lower impedance than commercial AC. The materials were used to fabricate electrodes for symmetrical supercapacitors, which displayed high energy densities and excellent cycling stability. This work provides an environmentally benign strategy for the re-use of waste PI film.

Automated summary

This study utilized waste PI film to fabricate flaky porous carbon materials with tailored pore structure and functional groups through KOH activation, achieving excellent electrochemical performance. The materials showed high specific capacitance, good capacitance retention rate, and low impedance, making them promising electrode materials for supercapacitors.