Synthesis of Li Conductive Polymer Layer on 3D Structured S Cathode by Photo-Polymerization for Li–S Batteries

Abstract

The dissolution of lithium polysulfide (Li2Sx, 4 ≤ x ≤ 8, LiPS) during charge/discharge testing is a critical issue hindering the practical application of lithium-sulfur batteries (LSBs). To suppress LiPS dissolution, we propose a facile method to fabricate a Li-ion-conductive polymer layer by photopolymerization. The electrochemical performance of LSBs was investigated by preparing small pouch cells containing a three-dimensional (3D) structured sulfur-based cathode that either was or was not layered with the new polymer. Analysis of the electrolyte in the LSB pouch cell by UV-Vis spectroscopy revealed that a 3D S cathode with polymer layer shows a good discharge capacity of 535 mA h g−1 and a coulombic efficiency (CE) of over 96% after 40 cycles. In comparison, the 3D S cathode without a polymer layer has a poor discharge capacity of 389 mA h g−1 and a CE of over 22% after 40 cycles. The dissolution suppressing ability of our new polymer layer demonstrates promise for the practical application of LSBs.