A High-Performance Symmetric Supercapacitor from Porous Activated Carbon under Compression

The realization of biomass-derived supercapacitors of high performance is of practical importance for the manufacturing of supercapacitors from green and renewable sources. Herein, the feasibility of constructing high-performance supercapacitors from potato-derived activated carbon (AC) is demonstrated. The potato-derived AC is produced from potato mash through hydrothermal treatment and high-temperature activation with KOH as agent. The supercapacitors with aqueous electrolyte of 6 m KOH and a mass loading of 5 mg per electrode achieve a specific gravimetric capacitance of 333.7 F g⁻¹ per electrode and a specific energy of 11.75 W h g⁻¹ at a specific power of 197.6 W kg⁻¹ at a current density of 0.4 A g⁻¹ under a nominal compressive stress of 7.96 MPa. The supercapacitors with a mass loading of 10 mg per electrode achieve the maximum specific gravimetric capacitance of 340.6 F g⁻¹ and a specific energy of 11.75 W h g⁻¹ at a specific power of 194.2 W kg⁻¹ at a current density of 0.4 A g⁻¹ under a nominal compressive stress of 7.96 MPa. Increasing the compaction of electrode materials under compressive stress has the potential to increase the electrochemical performance of supercapacitors.