Hierarchical Porous Nitrogen-Doped Carbon Constructed of Crumpled and Interconnected Graphene-Like Nanosheets for Sodium-Ion Batteries and All-Solid-State Symmetric Supercapacitors

Hierarchical porous N-doped carbon constructed of interconnected and crumpled graphene-like nanosheets (designated as HGOCN-A) is prepared by combining NaCl templating with KOH activation through the solid-state pyrolysis of a urea and glucose complex. The self-assembled soluble NaCl/KOH crystals serve as an insitu template and support for the production of carbon nanosheets with 3D hierarchical porous structure, and chemical activation from KOH benefits the formation of abundant mesopores between 2 and 50 nm in size. Owing to the synergistic effect associated with the 2D morphology, the high BET surface area, enriched nitrogen doping, as well as a more appropriate pore-size distribution, the HGOCN-A demonstrates excellent electrochemical behaviors as electrode materials for sodium-ion batteries (SIBs) and all-solid-state symmetric supercapacitors. For SIBs, the HGOCN-A anode exhibits a high capacity of 195 mAhg(-1) at 0.1 Ag-1 after 200 cycles, a long cycling stability with a capacity of 164 mAhg(-1) after 400 cycles at 0 .5 Ag-1, and an excellent rate performance with a capacity of 108 mAhg(-1) at 10 Ag-1. For all-solid-state symmetric supercapacitors, the fabricated device possesses a superior capacitive property of 212 Fg(-1) at 0.5 Ag-1, a high capacitance retention with 142 Fg(-1) at 10 Ag-1, and outstanding cycling stability with 98% capacitance retention after 2000 cycles at 1 Ag-1. HGOCN-A has great potential in future applications for high-performance electrochemical energy storage devices.