Conformal porous carbon coating on carbon fiber cloth/NiS2 composites by molecular layer deposition for durable supercapacitor electrodes

To solve the poor cyclability of faradic supercapacitors (SCs), the authors reported a unique porous carbon (PC) coating with "gap shell" structure on carbon fiber cloth (CFC)/NiS2 materials. This gap shell PC coating was fabricated by combining atomic layer deposition (ALD) Al2O3 and molecular layer deposition alucone, followed by carbonization and etching. The as-prepared CFC/NiS2/PC composites were directly used as binder-free electrodes for SCs. Benefited from its novel nanostructure, the CFC/NiS2/PC electrode shows a large specific capacitance of 1034.6 F/g at 1 A/g and considerable rate capability of 67% capacitance, retaining ratio within 1-20 A/g. The cyclability of the CFC/NiS2/PC electrode is enhanced by 50% relative to the mere CFC/NiS2 after 2000 cycles, which is attributed to the gap and electrically conductive PC coating. Hence, this work provides a promising approach to design gap shell layer for improved cyclability of faradic SCs and other practical applications in energy storage electronics.