Preparation and properties of irradiated modified polyacrylonitrile/thermoplastic polyurethane lithium-ion battery separator

Polyacrylonitrile (PAN) separator has excellent electrochemical performance, and has been widely concerned as a lithium ion battery separator material, but its mechanical strength and heat resistance are still insufficient problems. In this paper, polymeric thermoplastic polyurethane (TPU) composed of soft segment and hard segment was blended with PAN, and the prepared fiber film was modified by ⁶⁰Co γ to prepare a new type of lithium-ion battery separator. Through FTIR, it was found that the irradiation-modified PAN/TPU membrane had cyclization reaction among PAN molecules, and C=N—N bond crosslinking appeared between PAN and TPU molecules. The introduction of ring and crosslinking structures both improved the mechanical and heat resistance properties of the membrane. In addition, the membrane modified by 100 kGy had excellent electrochemical properties. It has a high electrolyte uptake (552%) and porosity (68.2%), an electrochemical stability window of 5.42 V, an interface impedance of 149.44 Ω, and an ionic conductivity of 1.68×10⁻³ S/cm, all of which are better than the separator before irradiation. After cycling 100 at 1 C, the discharge capacity retention rate is 96.53%. It also shows excellent magnification performance in cyclic test.