Dual-Modified Electrospun Fiber Membrane as Separator with Excellent Safety Performance and High Operating Temperature for Lithium-Ion Batteries.

Abstract

Polyacrylonitrile/Boric acid/Melamine/the delaminated BN nanosheets electrospun fiber membrane (PB3N1BN) with excellent mechanical property, high thermal stability, superior flame-retardant performance, and good wettability are fabricated by electrospinning PAN/DMF/H3BO3/C3H6N6/ the delaminated BN nanosheets (BNNSs) homogeneous viscous suspension and followed by a heating treatment. BNNSs are obtained by delaminating the bulk h-BN in isopropyl alcohol (IPA) with an assistance of Polyvinylpyrrolidone (PVP). Benefiting from the cross-linked pore structure and high-temperature stability of BNNSs, PB3N1BN electrospun fiber membrane delivers high thermal dimensional stability (almost no size contraction at 200°C), excellent mechanical property (19.1MPa), good electrolyte wettability (contact angle about 0°), and excellent flame retardancy (minimum total heat release of 3.2MJm-2). Moreover, the assembled LiFePO4/PB3N1BN/Li asymmetrical battery using LiFePO4 as the cathode and Li as the anode has a high capacity (169mAhg-1 at 0.5C), exceptional rate capability (129mAh g-1 at 5C), the prominent cycling stability without obvious decay after 400 cycles, and a good discharge capacity of 152mAh g-1 at a high temperature of 80°C. This work offers a new structural design strategy toward separators with excellent mechanical performance, good wettability, and high thermal stability for lithium-ion batteries.