Glass Microfiber Interlayer for Polysulfide Retention in Lithium-sulfur Cathodes

Abstract

In this study, a glass microfibers interlayer (GMI) was used at the interface of the cathode and electrolyte in lithium-sulfur batteries to prevent polysulfides loss from the cathode which contributes to capacity and coulombic efficiency fades during cycling. The interlayer's performance was evaluated using full-cell studies and various visual experiments at commercially relevant sulfur areal loadings. Cells with sulfur loading of 4 mg cm⁻² consistently had initial capacities exceeding 1200 mAh g⁻¹ and reached a stable performance at around 900 mAh g⁻¹ after 2 cycles at 2.23 mA cm⁻². After 200 cycles the capacity retention remained robust at 95 %, marking an average decay rate of only 0.016 % per cycle. Cathodes with 2.8 mg cm⁻² at 1.57 mA cm⁻² rate and cathodes with 2 mg cm⁻² at 3.3 mA cm⁻² high rate exhibit improved rate capability and excellent stability over 400 cycles and 500 cycles respectively with 20 % more capacity retention than non-GMI cells. Post-failure analyses of the cell components revealed the GMI's role in controlling the concentration of soluble polysulfides at the anode and a suitable candidate that can be used alone or in tandem with other approaches to help overcome one of the major problems in lithium-sulfur batteries.