Sugarcane waste-derived activated carbon for lithium-sulfur batteries with enhanced performance by thiourea doping

In this work, bio-renewable sugarcane bagasse and leaf were utilized for the preparation of activated carbon (BAC and LAC), which was then employed as the host material in lithium-sulfur (Li-S) batteries. The activated carbon, for the first time, was doped with nitrogen and sulfur via the addition of thiourea during the synthesis of carbon char via a simple, one-step hydrothermal method. The activated carbon was used to fabricate the cathodes of the CR2032 coin cells. The amount of added thiourea was found to influence the nitrogen/sulfur content, porosity, amorphous/graphitic structure, and performance of the activated carbon. At 0.2C, BAC2 (4.15 wt% thiourea doping) gave the highest specific capacity of 478 mAh⸳g-1 among the bagasse-derived activated carbon, while LAC3 (8.3 wt% thiourea doping) yielded the highest specific capacity of 521 mAh⸳g-1 among the leaf-derived activated carbon. They also demonstrated an excellent capacity retention of 72% and 83%, respectively, after 100 cycles. Furthermore, thiourea doping also improved the rate performance, by providing fast interfacial processes. Based on these results, the obtained activated carbon demonstrates the potential for the fabrication of high-performance Li-S batteries. Also, this work highlights the practical utilization of both sugarcane wastes for these emerging energy storage devices.