Mussel stimulated modification of flexible Janus PAN/PVDF-HFP nanofiber hybrid membrane for advanced lithium-ion batteries separator

Bicomponent polyacrylonitrile/Poly(vinylidene fluoride-co-hexafluoropropylene) (PAN/PVDF-HFP) Janus nanofibers based hybrid membrane was successfully prepared by parallel electrospinning technology. Subsequently, modified PAN/PVDF-HFP hybrid membrane (M-PAN/PVDF-HFP) was further fabricated via mimicking the adhesive of mussel by coating dopamine alternative through polymerization of catechol and tetraethylenepentamine (TEPA) in weakly alkali solution. M-PAN/PVDF-HFP maintains the abundant pore structure of the electrospun hybrid membrane and further provides excellent electrolyte infiltration with high porosity (82.09%) and outstanding electrolyte retention (553.23%). Simultaneously, the mechanical strength of the separator was significantly improved (14.36 MPa). Electrochemical studies displayed that the M-PAN/PVDF-HFP composite membrane delivered superior ion conductivity (2.81 mS/cm) and wide electrochemical stability window (∼5.25 V). The cell assembled by M-PAN/PVDF-HFP separator presented outstanding rate capability with high specific capacity of 147 mAh/g at 1 C and excellent cycle stability with discharge capacity of 120 mAh/g at 1 C after 600 cycles. Furthermore, M-PAN/PVDF-HFP separator exhibited ultra-flexibility with remarkable electrochemical performance after repeated bending for 500 to 1000 time. This work provides new insights into polyamine modified hybrid membranes for the potential practical applications in lithium-ion batteries separator.