Design of an Ultra-Highly Stable Lithium-Sulfur Battery by Regulating the Redox Activity of Electrocatalyst and the Growth of Lithium Dendrite through Localized Electric Field.

Abstract

Polysulfide shuttling and dendrite growth are two primary challenges that significantly limit the practical applications of lithium-sulfur batteries (LSBs). Herein, a three-in-one strategy for a separator based on a localized electrostatic field is demonstrated to simultaneously achieve shuttle inhibition of polysulfides, catalytic activation of the Li-S reaction, and dendrite-free plating of lithium ions. Specifically, an interlayer of polyacrylonitrile nanofiber (PNF) incorporating poled BaTiO₃ (PBTO) particles and coating with a layer of MoS₂ (PBTO@PNF-MoS₂) is developed on the PP separator. Theoretical calculations and experimental work show that the electric field generated at the membrane facilitates the fast and uniform transport of Li⁺ ions, thereby inhibiting dendrite growth. Additionally, the generated electric field promotes the MoS₂ catalytic activity toward the Li-S redox reactions, particularly by reducing the reaction barriers for both the solid-liquid and solid-solid conversions. As a result, symmetrical Li//PBTO@PNF/PP/PBTO@PNF//Li cells demonstrate remarkable stability over 1200 h, and LSBs with a PP/PBTO@PNF-MoS₂ composite separator maintain a specific capacity of 318.3 mA h g^-1 after 4000 cycles at 2C, with an ultralow capacity decay rate of 0.015%. In addition, the PBTO@PNF membrane also enhances the mechanical flexibility and thermal stability of the composite separator.