Developing flexible and safety-reinforced 3D polymer electrolytes based on polyethylene oxide for solid-state lithium metal batteries

Poly (ethylene oxide) (PEO) is a potential material for solid-state lithium batteries . However, the present polymer electrolyte is hampered by its low ionic conductivity at room temperature and poor mechanical properties, which are significant barriers to its practical application. Herein, we designed a high-performance composite solid electrolyte (PLSP) by incorporating PEO, LiTFSI, and the solid plasticizer butanedinitrile into a 3D polyethylene terephthalate (PET) nonwoven framework with excellent mechanical properties. The PLSP achieved an impressive ionic conductivity of 5.45 × 10 −4 S cm −1 , nearly 100 times higher than the original PEO electrolyte (6.1 × 10 −6  S cm −1 ) at room temperature. Additionally, the optimized composite electrolyte exhibited an extended electrochemical window of up to 5.2 V vs. Li + /Li and a remarkable tensile strength exceeding 8.55 MPa. The stability of the lithium symmetrical battery's charge and discharge voltage platform after 400 h of cycling indicated favorable interfacial compatibility between the PLSP and lithium metal. Furthermore, the assembled Li/PLSP/LFP configuration displayed a discharge specific capacity of 131.4 mA h g −1 and a capacity retention of 93.8 % after 100 cycles at 1C at room temperature, highlighting the promising potential of the composite electrolyte for solid-state lithium batteries.