Hierarchical nanoarchitectonics of ZnCO3-templated porous carbon derived from lignite alkali extract for supercapacitor applications

Three-dimension (3D) hierarchically porous carbon (HZCP) was prepared through embedding zinc carbonate particles in the carbon skeleton followed by high-temperature activation and the decomposition of zinc carbonate. Under optimal experimental conditions of a carbon source-to-template mass ratio of 1:5, an activation temperature of 700 °C, and an activation time of an hour, the three-dimensional porous carbon HZCP-5 exhibited a specific surface area of 1865.8 m² g⁻¹, with micropores accounting for 90.83 %. Used as the supercapacitor electrodes, HZCP achieved a specific capacitance of 367.63 F g⁻¹ at a current density of 1 A g⁻¹ in a three-electrode system, maintaining 270.44 F g⁻¹ at 10 A g⁻¹ with a capacitance retention rate of 73.56 %. Additionally, these advantages could enable the devised capacitor to exhibit a capacitance retention of 95.45 % after 20,000 cycles at 1 A g⁻¹.