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

Abstract

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 (S₈) and Li₂S₂, catalyzed by a bifunctional carbon host/catalyst. The overall catalytic redox reaction at the sulfur cathode is represented as $S_8+{8Li}^{+}+8e\rightleftharpoons {4Li}_2{S}_2$. 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 Li₂S₂ within the cathode matrix. As a result, the adverse chemical interaction between dissolved polysulfides and the Li anode is mitigated.