3D poly(vinylidene fluoride–hexafluoropropylen) nanofiber-reinforced PEO-based composite polymer electrolyte for high-voltage lithium metal batteries

• PEO-based 3D CPE-5 was prepared by reinforcing with PVDF-HFP nanofibers and LATP particles. • The thickness of 3D CPE-5 is only 50 μm with excellent mechanical strength. • 3D CPE-5 displays high electrochemical window (5.21 V) and lithium transference number (0.49). • 3D CPE-5 shows excellent stability to Li-metal and effective lithium dendrite inhibition. • High-voltage Li/3D CPE-5/NCM811 battery shows excellent cycling stability at 0.1 and 0.5 c. Solid-state lithium metal batteries (SSLMBs) are considered as a promising energy storage technology due to their high energy density and safety. However, the relatively low conductivity of solid-state electrolytes and the high electrolyte–electrode interfacial resistance seriously limited the development of SSLMBs. In this work, the high-performance PEO-based composite polymer electrolyte (3D CPE-5) was successfully prepared by reinforcing with polyvinylidene fluoride–hexafluoropropylene nanofibers and Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) particles. The thickness of 3D CPE-5 is only 50 μm with high electrochemical window (5.21 V) and lithium transference number (0.49) at 60 ℃. In addition, the 3D CPE-5 shows excellent stability to Li–metal, so that Li–Li symmetric cells can run stably for more than 300 h under 0.1 mA cm −2 with low voltage polarization value (15 mV) and effective lithium dendrite inhibition. Finally, the high-voltage Li/3D CPE-5/NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) solid-state battery demonstrates excellent cycling stability at 0.1 and 0.5 C (60 ℃). The excellent safety performance of 3D CPE-5 highlights its remarkable advantages over liquid electrolytes and provide an effective design strategy of high-performance polymer electrolytes for SSLMBs.