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

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.