Facile and friendly preparation of N/S Co-doped graphene-like carbon nanosheets with hierarchical pore by molten salt for all-solid-state supercapacitor

Two-dimensional carbon nanosheets have aroused extensive interest in the fields of electrochemical energy storage and conversion. In this work, a facile and friendly method was applied to fabricate nitrogen/sulfur co-doped graphene-like carbon nanosheets with hierarchical pore structure and large specific area (1753.01 m² g⁻¹) under the assistance of molten salt possessing the effects of template and activation. The typical morphology could provide abundant ion transport channels to enhance their diffusion and expose more accessibly active sites after doping heteroatoms simultaneously, which enabled the electrode to manifest a specific capacitance of 262.43 F g⁻¹ under 1 A g⁻¹, better capacitance retention of 78.05% after increasing current density to 20 A g⁻¹ and superior cycle stability (96.28% after 10 000 cycles under 10 A g⁻¹) in 6 M KOH. More importantly, the assembled all-solid-state supercapacitor with the as-obtained product as electrodes delivered higher energy densities of 22.26 Wh kg⁻¹ and power density of 12 312.42 W kg⁻¹ (1 M Na₂SO₄ electrolyte). This investigation may provide a strategy towards the simple and environmental preparation of carbon materials utilized in energy storage.