Remediation of shuttle effect in a Li-sulfur battery via a catalytic pseudo-8-electron redox reaction at the sulfur cathode

• A novel catalytic process for the disproportionation of dissolved polysulfides was discovered. • A pseudo-8-electron sulfur redox reaction mechanism was postulated. • The presence of dissolved polysulfides in the electrolyte was significantly reduced. • Efforts to mitigate the polysulfide shuttle phenomenon were successful. A catalytic pseudo-8-electron redox reaction of sulfur is achieved by facilitating the disproportionation of high-order polysulfide ions in a Li-Sulfur battery. Electrochemically generated polysulfide ions (S x 2- , where 3 < x < 7) undergo rapid disproportionation into elemental sulfur (S 8 ) and Li 2 S 2 , catalyzed by a bifunctional carbon host/catalyst. The overall catalytic redox reaction at the sulfur cathode is represented as S 8 + 8 L i + + 8 e ⇌ 4 L i 2 S 2 . In contrast to physical or chemical confinement methods for polysulfide ions, this approach remediates the shuttle effect by swiftly converting soluble polysulfides in the electrolyte to elemental sulfur and insoluble Li 2 S 2 within the cathode matrix. As a result, the adverse chemical interaction between dissolved polysulfides and the Li anode is mitigated.