Shape-controlled synthesis of porous carbons for flexible asymmetric supercapacitors.

N-Doped carbon nanomaterials have gained tremendous research interest in energy storage because of their high capacitance and chemical stability. Here, N-doped porous carbons (NPCs) with multiple shape-controlled and tunable morphologies are developed through a direct one-step pyrolysis/activation method. Typically, NPC-700-1, which is 5 nm thick and 6 μm wide, shows a high surface area (1591.5 m2 g-1) and hierarchical micro-, meso-, and macroporous architecture. The maximum specific capacitance of the as-prepared carbon nanosheets is 406 F g-1 at 1 A g-1 in KOH electrolyte. Moreover, flexible all-solid-state asymmetric supercapacitor devices assembled from NPCs and NiCo2O4 deliver a superior energy density of 42.7 W h kg-1 at 794.6 W kg-1, and good cycling ability (94% after 10 000 cycles). All the results suggest that NPCs have great potential for high performance wearable electronics and energy storage devices.