Jackfruit waste derived oxygen-self-doped porous carbon for aqueous Zn-ion supercapacitors

Abstract

To fully harness the benefits of high energy density, strategic fabrication of hierarchical porous carbon (PC) materials is essential and highly impactful. In this study, oxygen-self-doped PC materials are synthesized from jackfruit waste (JK) through pyrolysis combined with chemical activation. The resulting material (JKPC-4) features abundant interfacial active sites and a short ions/electrons transfer distance, enhancing the ion adsorption capacity and kinetic behavior of the cathode. Additionally, the oxygen-rich functional groups contribute to increased pseudocapacitance and enhance the wettability and conductivity of the material. Consequently, the assembled JKPC-4//JKPC-4 symmetric supercapacitor in 2M Na₂SO₄ electrolyte exhibits a high energy density of 36.06 Wh kg⁻¹ at 647.94 W kg⁻¹. Furthermore, the JKPC-4//Zn device demonstrates a notable capacity of 225 mAh g⁻¹ at 0.1 A g⁻¹, exceptional rate capability (93 mAh g⁻¹ at 10 A g⁻¹), high energy density (154 Wh kg⁻¹), and impressive cycle stability, retaining 97 % of its capacity after 10,000 cycles at 10 A g⁻¹. The electrochemical process is studied using ex-situ characterization. Mechanistic studies have shown that the outstanding energy storage capability and charge-transfer processes of JKPC-4 stem from the synergistic interplay between oxygen heteroatoms and suitable pore structure.