Stable cycling of Li–S batteries by simultaneously suppressing Li-dendrite growth and polysulfide shuttling enabled by a bioinspired separator

Abstract

Lithium–sulfur (Li–S) batteries are very promising candidates for next-generation high-energy-storage devices. However, the uncontrollable Li dendrite growth and notorious polysulfide shuttling severely hinder their real-world applications. Herein, we report a bioinspired separator to simultaneously address these issues. The separator was prepared by the successive deposition of silicone nanofilaments and polydopamine on the Celgard®2400 separator. The separator has a 3D cross-linked network with abundant O, N-containing groups and Si–O groups, which can redistribute the Li⁺ in the electrolyte at the molecular level to realize fast Li⁺ diffusion and uniform Li⁺ flux. Thus, long-term stable Li stripping/plating is achieved even at a high current density of 10 mA cm⁻². Meanwhile, these polar groups can act as lithiophilic sites to effectively suppress polysulfide shuttling by forming Li–O and Li–N bonds with polysulfides. Consequently, the separator enables the stable cycling of the Li–S battery with high S loading CNTs/S cathode (4.3 mg cm⁻²). The battery features slow capacity decay (0.018% per cycle over 1000 cycles at 1.0C), high specific energy density (569.2 W h kg⁻¹) and high average coulombic efficiency (98.71%). This study demonstrates the potential of advanced separators for high-performance Li–S batteries by realizing stable electrochemical interfaces at the anode and cathode.