Nature-inspired self-activation method for the controllable synthesis of highly porous carbons for high-performance supercapacitors

The specific surface area (SSA) and pore structure are two critical factors that determine the energy storage performance of carbon-based supercapacitors. However, for biobased carbon electrodes, it is difficult to simultaneously control the pore structures and achieve high SSA. Herein, highly porous carbons (HPCs) with ultrahigh SSA and controllable pore structures are produced through hydrogel-controlled carbonization and activation process for glucose. Polyacrylamide (PAM) is used as the pore-forming agent, and pore structures can be regulated by controlling the content of PAM. The highest SSA of the HPCs reaches 3381 m² g⁻¹ with a 60% PAM content. Compared with the sample without PAM, the specific capacitance of HPCs-60 shows a 63% increase, reaching 441 F g⁻¹ at a current density of 0.25 A g⁻¹. Moreover, a KOH/PVA symmetric supercapacitor assembled from HPCs-60 not only exhibits an excellent energy density (10.9 Wh kg⁻¹ at a power density of 125 W kg⁻¹) but also has high cycling stability (∼10% loss over 20,000 cycles) and good flexibility. The as-prepared supercapacitors can provide stable power supplies for multiple electronic devices, indicating that the HPCs have enormous potential for use in high-performance electrochemical energy storage devices.