Flexible core-shell PAN/CNTs@PVDF-HFP/Uio-66-NH2 hybrid nanofibers membrane for advanced lithium-ion batteries separator

Flexible core-shell polyacrylonitrile (PAN)/carbon nanotubes (CNTs)@Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/Uio-66-NH2 (PC@PU) hybrid nanofiber membrane was prepared by coaxial electrospinning technology. PAN polymer and CNTs particles were used as core to improve the membrane structure stability for further ensuring the thermal stability of the separator. PVDF-HFP and Uio-66-NH2 nanoparticles were applied to reinforce the affinity of separator to electrolyte. The PC@PU composite membrane delivered high thermal stability and fantastic electrolyte affinity (545.76%). Furthermore, compared with Celgard 2325 commercial membrane, the PC@PU composite membrane exhibited higher porosity (80.22%) and higher Li+ conductivity (3.43 mS/cm), leading to superior rate performance and long-term cycle stability. The cell with the PC@PU hybrid membrane displayed high specific capacity of 143 mAh/g at 1C and only 0.0259% capacity attenuation of each cycle after 1000 cycles. In addition, the PC@PU composite membrane demonstrated remarkable flexibility, and the cells with bent separators exhibited outstanding electrochemical performance. Hence, the PC@PU hybrid nanofiber membrane can pave a way for the further application in the field of secondary batteries separator.