Thin, Flexible, and High-Performance Solid-State Polymer Electrolyte Membranes for Li-O2 Batteries

A solid-state lithium-oxygen battery (SSLOB) has become more attractive as a next-generation energy storage device, with the expectation of long-term safe and wide applications with superior energy density. However, the development of a thin and flexible solid-state electrolyte having good interfacial and chemical stability toward lithium metal and/or oxygen has been a big challenge. Accordingly, a solid-state composite electrolyte membrane has been prepared by impregnating polyethylene glycol (PEG) and succinonitrile plastic crystals (SNPCs) along with lithium bromide redox mediator into a porous polytetrafluoroethylene (PTFE) substrate for application in a SSLOB. The prepared thin electrolyte membrane (23 mu m) displays a high ionic conductivity of 1.03 mS cm(-1), a tensile strength of 46.5 MPa, and elongation at a break of 100% with excellent flexibility. It also exhibits a wide electrochemical stability window (similar to 4.9 V) and low interfacial resistance of 80 Omega cm(2). The SSLOB cell assembled with the synthesized XPEG/SNPC@PTFE electrolyte membrane shows excellent electrochemical stability during 277 cycles, maintaining a 1000 mAh g-1 discharge capacity. The low terminal voltage difference between the charge and discharge processes of these polymer electrolyte membranes (similar to 0.65 V) compared to those of liquid or other polymer electrolytes (similar to 1.4 V) is also an advantageous characteristic for their application in high-performance SSLOBs.

Automated summary

A solid-state lithium-oxygen battery (SSLOB) is a promising energy storage device with long-term safety and wide applications. However, the development of a thin and flexible solid-state electrolyte with good stability towards lithium and oxygen has been challenging.