Electrospun PAN membrane encapsulated in PEO as a polymer electrolyte for lithium metal batteries

Abstract

The novel two-step fabrication method of polymer electrolyte membrane was proposed. In the first step, the polyacrylonitrile nano fibrous membrane was prepared with the help of electrospinning. In the second step, the polyethylene oxide solution was prepared along with lithium salt and plasticizers. The solution was poured on the electrospun polyacrylonitrile to get polymer electrolyte membrane in the form of PAN membrane encapsulated in PEO. The polymer electrolyte membrane was boosted by the liquid LiPF₆ before assembled in the lithium metal batteries. The polymer electrolyte membrane was compared with the commercial Celgard separator when assembled in coin cell for the application of lithium metal batteries. The polymer electrolyte membrane outperformed and exhibited a good ultimate tensile strength of 20 MPa and the better thermal stability of 97 % at 305 °C. Moreover, the polymer electrolyte membrane also exhibited excellent ionic conductivity of 1.2 mS cm⁻¹, good lithium-ion transference number of 0.57 and uniform lithium plating/stripping cycles for up to 500 cycles without internal short circuiting. The polymer electrolyte membrane represented outstanding rate capability and exhibited the good discharge capacity of 141 mA h g⁻¹ after 100 cycles at 0.5 C rate.