Enhanced Performance of High Energy Density Lithium Metal Battery with PVDF-HFP/LAGP Composite Separator
Tian Liang, Wei‐Hua Liang, Jianhua Cao, Dayong Wu
Abstract
The development of high energy density lithium ion batteries puts forward requirements for separators. In this article, poly(vinylidene fluoride-hexafluoropropylene)/Li1.5Al0.5Ge1.5(PO4)3 composite membrane (PL) has been fabricated by electrospinning and with use of the dip-coating method as the separator of the lithium ion battery. With reference to the physical properties, PL has better mechanical strength than does its base membrane electrospun poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), and thermal stability and electrolyte uptake (215%) higher than those of the PP separator; with reference to the electrochemistry parameters, 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 a longer cycle life (144.7 mAh g–1 after 500 cycles at 0.2 C), a lower interfacial resistance change (71.19 Ω), and a higher rate capability as compared to the batteries that use the PP and electrospun PVDF-HFP separator. The above results reveal that the PL separator is an ideal choice for high energy density lithium batteries.