Synergistic effect of waste sisal fiber-derived carbon and graphene oxide for performance enhancement of sulfur-based thermally regenerative batteries

Sulfur-based thermally regenerative batteries (STRBs) offer a promising approach for low-grade waste heat recovery. To enhance their power output, we develop a sulfur electrode using a composite of sisal fiber-derived activated carbon (SFAC) with a porous structure and graphene oxide (GO) from waste biomass. The SFAC framework enhances the electrochemically active surface area while simultaneously reducing electron transport resistance, thereby boosting overall electrode performance. The incorporation of GO improves hydrophilicity and ion transport. The synergy between the two components significantly boosts power density and cycling stability. The STRB with the SFAC-GO@S electrode achieves a maximum power density of 56.9 W m−2, which is 57.6% higher than that of a bare carbon cloth-based sulfur electrode. The GO encapsulating effect on sulfur particles within SFAC pores yields a capacity retention of 89.6% after 30 cycles. An optimal GO concentration of 1.5 mg ml−1 gives the highest power density of 70.7 W m−2. Excessive GO causes agglomeration and blocks ion transport, degrading performance.