Seaweed-derived hierarchical porous carbon for high-rate performance supercapacitors

Abstract

To address the issues of slow ion transport and insufficient rate performance in commercial activated carbon (AC) due to its micropore-dominated structure, this work successfully constructed a porous carbon material (SPC) featuring an interconnected hierarchical pore network of macropores, mesopores, and micropores. This was achieved using renewable seaweed as the precursor and environmentally friendly NaHCO₃ as the activator through high-temperature chemical activation. This unique structure enables a synergistic mechanism of macroporous rapid diversion, mesoporous directional guidance, and microporous efficient storage, fundamentally optimizing ion transport kinetics. Benefiting from this design, the SPC electrode exhibited outstanding rate performance, maintaining a capacitance retention of 70.2% (191 F g⁻¹) at a high current density of 250 A g⁻¹, significantly outperforming AC (29.0%, 82 F g⁻¹). Symmetrical supercapacitors assembled with SPC achieved an energy density of 27.1 Wh kg⁻¹ and a power density of 47 450 W kg⁻¹ in organic electrolytes. This work not only provides a novel design approach for developing high-rate performance supercapacitor electrode materials but also demonstrates a green and sustainable preparation pathway.