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.