Sustainable sulfur hosts from durian shells-derived porous carbon for enhanced cycling stability in lithium‑sulfur batteries

Abstract

This study investigates the impact of porous carbon derived from waste durian shells on the performance of electrochemical lithium‑sulfur (LiS) batteries. Two different preparation methods were employed to synthesize porous carbon: a one-step KOH activation via hydrothermal carbonization (PDRH) and a two-step process involving biochar activation followed by carbonization (PDRB). The synthesized porous carbons were characterized using BET, SEM, TEM, XRD, Raman, and TGA to determine their chemical and physical properties. Despite similar surface areas, the two samples exhibited different pore volumes and pore size distributions. PDR-B primarily displayed mesopores (2–30 nm) after activation, whereas PDR-H showed a combination of micro/mesopores (1.5–8 nm). PDR/S composites were prepared by melt-diffusion method with a 7:3 mass ratio of sulfur to carbon. Electrochemical performance testing indicated that the PDR-H/S composite exhibited superior cycling stability, retaining 50 % of its capacity after 400 cycles at 0.2C, and delivered a higher discharge capacity of 583.7 mAhg⁻¹ at 0.1C compared to the PDR-B/S composite, which achieved 477 mAhg⁻¹.The improved long-term cycling stability of PDR-H/S is attributed to better sulfur confinement within its varied pore structure (micro/mesopores). The presence micro/mesopores in PDR-H appears to be more effective for sulfur confinement and thus leads to better battery performance. Additionally, the study highlights that, beyond surface area and pore volume, the pore size distribution plays a crucial role in determining the electrochemical performance of the PDR/S composites.