A multifunctional zipper-like sulfur electrode enables the stable operation of lithium-sulfur battery through self-healing chemistry

Abstract

Lithium-sulfur (Li-S) battery is a promising candidate for high-energy storage devices due to its high theoretical capacity and energy density. However, both structural change and drastic phase transfer arising from irreversible and unstable conversion between S/Li2S and polysulfides during cycling would lead rapid capacity decay and short cycle-life for lithium-sulfur battery. Herein, inspired by such principle of zippers, a self-healing zipper-like sulfur electrode was designed, which was fabricated by organo-polysulfide (-Sx-) polymer binder (PSPEG) and sulfur nanocomposite with organo-polysulfide (-Sx-) chains grafted on carbon host (CPS/S). The organo-polysulfide (-Sx-) chains on/in the carbon host or binder can not only function as redox mediator to control phase transfer between S/Li2S and polysulfides but also act as “zipper teeth” and “zipper sliders” respectively to repair the electrode spontaneously as the sulfur electrode suffered from mechanical damages and cracks. Owing to this unique zipper-like electrode design, the structural collapse and the agglomeration of S/Li2S were effectively suppressed. Consequently, the sulfur electrode exhibits both high capacity and excellent cycling stability, showing a specific capacity of 812 mA h g − 1 at 1.0 C after 300 cycles. Moreover, as the sulfur loading was increased to 7.6 mg cm−2, the CPS/S+PSPEG electrode can still deliver a high areal capacity of 6.47 mA h cm−2 with a low electrolyte/sulfur ratio (4.5:1, µL:mg) after 60 cycles, which verifies the feasibility of the zipper-like electrode design.