A robust polymeric binder based on complementary multiple hydrogen bonds in lithium-sulfur batteries

Abstract

The practical application of sulfur cathodes in traditional lithium–sulfur batteries has been hindered by the substantial deterioration of the sulfur electrode due to the polysulfide shuttling effect and the large volume expansion of the electrode during charge/discharge cycling. The resolving of this issue demands for a robust binder to hold the polysulfide/sulfur particles, but without causing severe disintegration of the electrode. A polar polymeric binder with high mechanical strength was designed and synthesized for use in high-performance sulfur cathodes. The complementary multiple hydrogen bonds formed in the polymeric binder significantly enhanced the adhesive strength of the binder, and buffered the dramatic volume expansion of the sulfur cathode during cycling. The strong physical and chemical interactions between the functional groups (e.g. carboxyl and tertiary amine groups) of the binder and the polysulfides effectively mitigated the shuttling effect in the Li–S batteries. As a consequence, the sulfur cathode exhibited excellent electrochemical performance at a high sulfur loading, yielding an initial discharge capacity of 627.8 mA h g−1 with sulfur loading up to 9.610 mg cm−2 at a rate of 0.2C, corresponding to an aerial capacity of 6.03 mA h cm−1. The present work opens a new avenue for constructing a high-performance Li–S battery using a simple and effective binder.