Binder-Free Electrode from Hemp-Derived Porous Carbon for Li-Sulfur Battery

Abstract This study explores a process to prepare porous carbon - based electrode from hemp (Cannabis Sativa L.), a biomass source, without using binder. Hemp-bast fibers were obtained from three retting processes: water, bacteria, or chemicals. These retted fibers were processed into uniform composite fiberboard with a thickness of less than 0.5 mm, and then carbonized and activated to obtain the carbon boards with surface area greater than 500 m2/g. This bio-based carbon board is used directly as the carbon host material without using binder for lithium-sulfur (Li-S) batteries and is called binder-free bio-based carbon electrode. The certain flexibility with minimum mechanical strength enables the binder-free bio-based carbon electrode to be handled without breaking during electrode processing. Li-S batteries fabricated from the binder-free bio-based carbon electrode show a stable cycling performance with a specific capacity of 833 mAh g-1 after 80 cycles. Compared with the electrodes made from carbon powders with polyvinylidene fluoride binder, the binder-free bio-based carbon electrode showed a 60% increase in capacitance. This binder-free bio-based carbon electrode is made solely from biomass without using polymer binders. It not only enhances the performance of the Li-S batteries but also reduces their environmental impact due to the use of bio-based carbon with no polymer binder.