Nitrogen-doped mesoporous carbon thin film for binder-free supercapacitor

•Crystal growth induced mesopores were realized in gelatin/HKUST-1 mesoporous films.•The mesoporous gelatin/HKUST-1 thin film was carbonized to free-standing nitrogen-doped mesoporous carbon thin film.•The resulted nitrogen-doped mesoporous carbon thin film demonstrates high capacity and long cycling stability for binder-free supercapacitor.

Free-standing nitrogen-doped mesoporous carbon films were successfully prepared by carbonizing gelatin/HKUST-1 composite films, which converted from gelatin/copper hydroxide nanostrands composite films. Gelatin provides the sources of both carbon and nitrogen. The formation of HKUST-1 crystals expanded the gelatin matrix and produced porous structures which were reserved during the carbonization process. The mesoporous structures of the prepared carbon film were easily wetted by electrolytes and more suitable for rapid ionic migration. This mesoporous nitrogen-doped carbon film was explored as a binder-free electrode for supercapacitor, which exhibited highest specific energy of 28.1 W h kg−1, specific capacity of 316 F g−1 at a current density of 0.5 A g−1, 168 F g−1 at a current density of 5 A g−1, and high capacitance retention of 92.9% with degrading of 0.00064% after charging/discharging 11,000 cycles.

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