Cathode-supported solid polymer electrolyte with solvate ionic liquid and polysulfide modification towards rechargeable lithium metal batteries

Abstract

Aimed at the application bottlenecks of the poly(ethylene oxide) (PEO)-based solid polymer electrolyte (SPE) relating to low ionic conductivity and unstable interface chemistry on both electrodes, Li+-conductive solvate ionic liquid (SIL) and soluble long-chain polysulfide (Li2S6) were introduced into the SPE as liquid plasticizer and functional additive, respectively, meanwhile a integrated structure characterized by cathode-supported SPE was adopted for enhancing the interface contact. The reformative PEO-based SPE exhibits excellent comprehensive properties in the ionic conductivity, Li ion transfer number, oxidation potential and Li metal compatibility. Especially, the moderate addition of Li2S6 is found to not only decrease the PEO crystallinity by strong interaction and uniform dispersion, but also effectively stabilize the Li surface and suppress dendrite growth by chemical reduction. The synergistic effect of the two functional agents and the integrated design endow the Li metal battery with high reversible capacity and superior cycle stability operating at room temperature.