Large-scale synthesis of highly porous carbon nanosheets for supercapacitor electrodes

• 2D porous carbon nanosheets with the thickness of <100 nm were obtained.
• The specific surface area is up to 2266.6 m2 g−1.
• The specific capacitance reaches 384 F g−1 at 0.1 A g−1.
• The capacity retention is 96.1% after 3000 charging-discharging cycles.

Two-dimensional (2D) porous carbon nanosheets were synthesized by a facile, low-cost, and scalable method. In this method, glucose was used as a carbon precursor and sodium chloride was employed as a water soluble template. The highly porous carbon nanosheets were prepared by the carbonization of glucose and sodium chloride and the following KOH chemical activation. The as-prepared carbon nanosheets (ACs-NaCl) have a thickness of less than 100 nm. The porous microstructure shows that the porosity of ACs-NaCl consists of essentially micropores with average pore size of ∼0.8 nm. In addition, they possess a large specific surface area up to 2266.6 m2 g−1, which is much higher than that of activated carbons (ACs) obtained without adding NaCl (1036.77 m2 g−1). The ACs-NaCl electrode exhibits a high specific capacitance of 384 F g−1 at the current density of 0.1 A g−1, excellent rate capability and good cycling durability in 6 M of KOH electrolyte. The enhanced capacitive performance of the ACs-NaCl electrode can be attributed to its unique structure that allows the short diffusion paths of electrolyte ions.