High well‐matched energy gravimetric–volumetric symmetric super‐capacitor derived from hollow paper stack‐like biomass‐based functional carbon.

BACKGROUND: Two‐ and three‐dimensional porous activated carbon (C)‐based symmetrical supercapacitors show great potential for extraordinary gravimetric performance as sustainable energy storage. However, the applications of portable and microdimensional supercapacitors are limited by their low volumetric performance stemming from reduced density resulting from increased porosity and high fabrication costs. This study aimed to demonstrate the high gravimetric–volumetric performance of symmetrical supercapacitors from biomass‐based porous carbon‐sources materials through an environmentally benign development method. Unique porous C sourced from TENERA‐type palm oil stick waste was prepared using potassium hydroxide (KOH) as an activating agent. The electrode set resembled a solid plate with an encapsulation density of ≈1.40 g cm−3. RESULT: The study used superior gravimetric–volumetric electrode materials, including an adjusted specific surface area of 934 m2 g−1, single‐doped optimization, and a hollow paper‐stack‐like morphological structure with a high C content of 91%. The results showed that the best electrode in the 1 mol L−1 H2SO4 electrolytes exhibited a high gravimetric capacitance of 233 F g−1 and an extraordinary volumetric capacitance of 326 F cm−3 at 1 A g−1. Furthermore, their coulombic efficiency was ≈99.1% at 10 A g−1. The symmetrical electrode device performed a high gravimetric–volumetric energy density of 19.03 Wh kg−1 and 26.6 Wh L−1 at a maximum output power density of 1.7 kW kg−1 and 1.9 kW L−1, respectively. CONCLUSION: These results indicate that the applied method development and the C‐biomass‐based electrode material design could achieve a high, well‐matched gravimetric–volumetric performance balance in symmetric supercapacitor devices. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]