Polydopamine modification electrospun polyacrylonitrile fibrous membrane with decreased pore size and dendrite mitigation for lithium ion battery

Large pore size of fibrous membrane (FM) deteriorates the cycle lifetime and rate capabilities, and the way of obtaining FM with improved electrolyte wettability and decreased pore size is still challenging. Herein, we report a facile method for the fabrication of the polydopamine modification polyacrylonitrile (PDA@PAN) FM via the combination of the spin coating and electrospinning techniques. The PDA coating increases the fiber diameter and the surface roughness of the PAN fibers, thus decreasing the pore size and mitigating the lithium dendrite formation by uniformly distributing Li-ion flux. Meanwhile, PDA modification not only improves the affinity for electrolyte and enhances the ion conductivity (1.39 mS cm −1 ), but also doubles the stress strength (13.92 MPa) because of the formation of more adhesion structure. Consequently, both the Li/LiFePO 4 and Li/Li 4 Ti 5 O 12 cells involving PDA@PAN FM demonstrate more stable cycle life and better rate capability compared with those of cells based on PAN FM and Celgard membrane. The work also provides a promising separator fabrication strategy for other energy storage systems.