Hybrid carbon matrices enable the suppression of polysulfide shuttle effect in Li-S batteries

Lithium-sulfur (Li-S) batteries offer high theoretical energy density but face critical challenges due to sulfur's poor conductivity and the polysulfide shuttle effect. Here we report a novel cathode design utilizing a hybrid carbon matrix derived from buckwheat biomass and single-walled carbon nanotubes (SWCNT) to overcome these issues. The buckwheat-derived hard carbon (HC), obtained at 1000 °C, provides hierarchical porosity to anchor polysulfides and buffer sulfur expansion, while SWCNT (optimized at 6%) creates a conductive network. As a result, S@SP/HC/SWCNT cathode delivers an initial discharge capacity of ~ 1250 mAh g^- 1 at 0.1 C and retains ~ 60% of this capacity after 100 cycles with ~ 100% Coulombic efficiency. Overall, this sustainable, low-cost, and scalable carbon-sulfur cathode architecture effectively addresses key Li-S challenges and demonstrates strong promise for practical high-energy, long-life Li-S batteries.