Binder-free electrode from hemp-derived porous carbon for lithium–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 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 a 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 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. This 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.