Sandwich-Structured PEO-Based Composite Solid-State Electrolyte for Lithium-Sulfur Batteries

Abstract

Solid-state lithium-sulfur batteries (SSLSBs) employing poly(ethylene oxide)(PEO)-based electrolytes have garnered significant attention as a promising energy storage system due to their high specific energy, straightforward manufacturability and cost-effectiveness. However, the inherently low ionic conductivity of PEO-based electrolyte at room temperature and sluggish conversion kinetics of dissolved lithium polysulfides (LiPS) result in significant active material depletion through irreversible LiPS accumulation, ultimately hindering their practical application. Therefore, composite solid-state electrolyte by incorporating inorganic fillers into the PEO matrix has been proposed to address these challenges. In this work, PEO-TiO2 composite solid-state electrolytes with sandwich-structure containing inorganic oxide filler have been prepared for lithium-sulfur batteries by a simple and efficient solution casting method. The incorporating of TiO2 inhibits the shuttle effect of Li2Sx species, reduces the glass transition temperature of PEO and increases the amount of amorphous portion, thus improving the ionic conductivity and mechanical strength. The ionic conductivity of the CSE-5 electrolyte is 5.04×10-4 S cm-1 at 60 °C, the Li//CSE-5//Li cell could be stably cycled for 2400 h at a current density of 0.1 mA cm-2. The initial discharge specific capacity of the Li//CSE-5//S@C solid-state cell is 1054 mAh g-1 at 0.1 C, and it still can remain at 703 mAh g-1 after 100 cycles.