Sustainable Hierarchical Porous Carbon Materials from Tannic Acid for Supercapacitors

Hierarchically porous carbon materials (HPCMs) with tailored multi-scale pore architectures are highly promising for high-performance supercapacitors due to their combined advantages in ion transport and charge storage.In this study, HPCMs were synthesized from renewable tannic acid (TA) and environmentally benign potassium citrate (PC) via a green strategy involving ice-templating followed by direct carbonization.The ice-templating process facilitated the formation of macroporous channels, while in-situ activation by PC generated abundant micro-and mesopores, resulting in a well-interconnected hierarchical porous network.As the PC content increased, the specific surface area and total pore volume of the resulting HPCMs improved markedly, reaching 1311.4 m 2 g -1 and 0.76 cm 3 g -1 , respectively, for the optimized C-TAPC10 sample.Electrochemical measurements revealed that C-TAPC10 delivered an outstanding specific capacitance of 311.66 F g -1 at 1 A g -1 in a three-electrode system using 6.0 M KOH electrolyte, along with moderate rate capability (retaining 39.90% at 50 A g -1 ), and low internal resistance.When assembled into a symmetric two-electrode device, the material achieved a high power density of 10.0 kW kg -1 and exhibited exceptional cycling durability, retaining nearly 100% of its initial capacitance after 20,000 charge-discharge cycles.These results demonstrate that the TAPC-derived HPCMs offer a sustainable, scalable, and cost-effective route to fabricating high-performance electrode materials.The integration of bioderived carbon precursors and mild activation conditions presents a viable pathway for the development of next-generation eco-friendly supercapacitors.