Ultra–thin ePTFE–enforced electrolyte and electrolyte–electrode(s) assembly for high–performance solid–state lithium batteries

Abstract

Challenges including low stability, excessive thickness, a low ionic conductivity of current solid–state electrolytes, and large interfacial resistance in solid–state lithium batteries (SSLBs) hinder their application. Herein, an ultra–thin electrolyte (∼20 μm) was prepared by using expanded porous polytetrafluoroethylene (ePTFE) as a framework and filling the pores with a hybrid electrolyte; it exhibited a high stability, mechanical strength, flexibility, and ionic conductivity (0.27 mS cm−1). A new mechanism for fast lithium-ion conduction in the composite electrolyte was creatively proposed, whereby the interface orients and concentrates lithium ions to accelerate ion transport. An electrolyte–electrode(s) assembly (EEA) was developed by directly spraying active material(s) with highly dispersed electrolytes on the electrolyte. EEA–based copper– and aluminum–free SSLBs with or without a low-dose liquid electrolyte achieved an excellent performance at room temperature. Furthermore, EEA–series–connected pouch batteries demonstrated high voltage, safety, and performance, making our ultra–thin electrolyte and EEA promising for the development of SSLBs.