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

ACS Nano. 2024 Dec 20. doi: 10.1021/acsnano.4c12217. Online ahead of print.

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.

Keywords: ferroelectric engineering; interlayer; lithium dendrite; lithium−sulfur battery; sulfur reduction process.