Carbon-Intercalated Montmorillonite as Efficient Polysulfide Mediator for Enhancing the Performance of Lithium–Sulfur Batteries

Abstract

The traditional separator plays a significant role in rechargeable lithium-ion batteries due to the customized features that allow ions to transfer freely with low energy barriers. However, in the lithium–sulfur battery, the commercial separator shows feeble ability for promoting the conversion of accumulated long-chain polysulfides to the short-chain polysulfides on the surface of the cathode. In this work, a carbon-intercalated montmorillonite is designed to release the imprisoned capacity of the sulfur cathode by activating the accumulated long-chain polysulfides on the surface of the cathode. Benefiting from the advantages of carbon-intercalated montmorillonite, the lithium–sulfur battery achieves a high discharge capacity of 818 mAh g–1 over 300 cycles at a current density of 1 mA cm–2 with a sulfur loading of 2.6 mg cm–2. The systematic analyses by cyclic voltammetry and AC impedance reveal that the regulation of redox environment on the cathode surface by reducing the accumulated long-chain polysulfides to short-chain sulfides is a scalable solution for constructing the actual lithium–sulfur batteries.