Enhanced\nPerformance of High Energy Density Lithium\nMetal Battery with PVDF-HFP/LAGP Composite Separator

Abstract

The\ndevelopment of high energy density lithium ion batteries puts\nforward requirements for separators. In this article, poly­(vinylidene\nfluoride-hexafluoropropylene)/Li_1.5Al_0.5Ge_1.5(PO₄)₃ composite membrane (PL) has\nbeen fabricated by electrospinning and with use of the dip-coating\nmethod as the separator of the lithium ion battery. With reference\nto the physical properties, PL has better mechanical strength than\ndoes its base membrane electrospun poly­(vinylidene fluoride-hexafluoropropylene)\n(PVDF-HFP), and thermal stability and electrolyte uptake (215%) higher\nthan those of the PP separator; with reference to the electrochemistry\nparameters, PL has an ionic conductivity of up to 3.18 mS cm^–1 at RT and a wide electrochemical window of 5.3 V (vs Li⁺/Li). The NCM811||Li battery that uses the PL separator exhibits\na longer cycle life (144.7 mAh g^–1 after 500 cycles\nat 0.2 C), a lower interfacial resistance change (71.19 Ω),\nand a higher rate capability as compared to the batteries that use\nthe PP and electrospun PVDF-HFP separator. The above results reveal\nthat the PL separator is an ideal choice for high energy density lithium\nbatteries.