Chaku Seed‐Derived Hierarchical Porous Bio‐Carbon for High‐Performance Supercapacitors and Efficient Iodine Host in Zinc‐Iodine Batteries

ABSTRACT

In light of the dual carbon goals, transforming waste biomass into high‐value‐added carbon materials has emerged as a research hotspot in electrochemical energy storage. In this study, a multistep process was developed to convert biomass Chaku seed waste into hierarchical porous nitrogen‐doped carbon (CKB) using a ball‐milling‐assisted method followed by high‐temperature pyrolysis. Due to the pseudocapacitive contribution from CKB's substantial nitrogen doping, it exhibits a high specific capacitance of 294.0 F g ⁻¹ (at 2.0 A g ⁻¹ ) in supercapacitor electrode materials and maintains a high rate performance of 251.0 F g ⁻¹ (85.4%) even at a high current density of 20.0 A g ⁻¹ . Meanwhile, based on a rational micro/mesoporous structure design—an ultra‐high specific surface area of 2671 m ² g ^{− 1} —the optimal sample exhibits outstanding iodine adsorption capacity. The assembled zinc–iodine battery exhibits a high specific capacity of 139.5 mA h g ^{− 1} at 0.1 C (95.8 mA h g ⁻¹ at 1.0 C), with a capacity retention rate of 94.0% after 10,000 charge/discharge cycles. These results indicate that Chaku‐based biomass‐derived carbon has potential for high‐performance electrochemical energy storage, particularly in supercapacitors and zinc–iodine batteries.