A polyolefin separator reinforced inorganic/organic composite electrolyte for quasi-solid-state Lithium-sulfur batteries with high cycle stability and long lifespan

Abstract

Lithium-sulfur (Li-S) batteries are considered a promising next-generation energy storage system due to the high energy density and the low cost. However, the severe shuttle effect of polysulfide and the security issue caused by organic liquid electrolyte and lithium metal anode have hindered their commercial application. Herein we achieved a polyolefin commercial separator reinforced inorganic/organic composite electrolyte (denoted as Com-LATP) via coating the polypropylene (PP) separator with the composite of polymethyl methacrylate/poly(vinylidene fluoride) (PMMA/PVDF) modified with Li1.3Al0.3Ti1.7(PO4)3 (LATP). The Com-LATP electrolyte (thickness: ∼30 um) exhibits remarkable tensile strength of 103 MPa, an ionic conductivity of 0.47·mS cm-1 with the Li+ transfer number of 0.45, which is beneficial for the uniform Li+ flux and the stable striping and plating of Li metal. The Li symmetrical batteries equipped with this Com-LATP exhibited stable cycling for over 350 h. Meanwhile, the Com-LATP electrolyte with the special dense structure can hinder the polysulfide diffusion. The developed quasi-solid-state lithium-sulfur batteries have demonstrated impressive cycling stability with an initial specific capacity of 1184.8 mA h g-1 at a discharge rate of 0.2 C, maintaining performance over 200 cycles. Additionally, they exhibited outstanding rate capability, retaining a reversible capacity of 710.4 mA h g-1 even at a higher discharge rate of 2 C. This research introduces an innovative structural design approach for high-performance quasi-solid-state Li-S batteries, which holds significant promise for advancing the commercialization of lithium-sulfur battery technology.