New insights into designation of single-ion conducting gel polymer electrolyte for high-performance lithium metal batteries

Abstract

Single-ion conducting polymer electrolytes (SIPEs) are promising separator/electrolyte materials in lithium metal batteries (LMBs) owing to their high lithium-ion transference numbers. However, the low ion conductivity and poor interfacial compatibility limit their practical application. The effective structural design and the highly porous membrane preparation are of significance for surmounting above issues. Here, a high-performance fire-resistant phosphine based SIPE with semi-interpenetrating polymer network is designed and its highly porous electrospun nanofiber membrane ( nf -sIPN-PECB) is subsequently prepared. After interpenetrated by 1 M LiPF 6 in EC/PC electrolyte, the nf -sIPN-PECB/1M LiPF 6 in EC/DMC electrolyte delivers ultrahigh ion conductivity of 2.5 mS cm −1 and excellent interfacial compatibility for achieving LiFePO 4 cathode LMB with a high discharge capacity of 166 mA h g −1 at 0.1C and 110 mA h g −1 at 6.0C. Moreover, the nf -sIPN-PECB/1M LiPF 6 in EC/DMC electrolyte demonstrates a high lithium-ion transference number of 0.64, endowing LMBs with excellent inhabitation of lithium dendrite growth. Therefore, ultra-long lifespan of 1000 cycles for the LMBs with ignorable capacity decay was successfully achieved. Furthermore, the good fire-retardant, high thermal dimensional stability and excellent flexibility drag LMBs out of severe safety hazards. A high-performance fire-resistant phosphine based SIPE (Li-PECB) with semi-interpenetrating polymer network is well-designed for simultaneously achieving the excellent fire-retardancy, good mechanical strength and enhanced ionic conductivity of the highly porous electrospun nanofiber membrane ( nf -sIPN-PECB). The molecular-scale mixture between PVDF-HFP binder and Li-PECB is successfully approached during in-situ polymerization process. • 3D IPNs of highly porous electrospun nanofiber membrane was prepared. • The porous electrospun nanofiber membrane displays enhanced mechanical strength due to 3D IPNs. • The nf -sIPN-PECB display uniform morphology and molecular level dispersion of components. • The enhanced lithium ion transference number was obtained for suppress lithium dendrite growth. • The promising elevated temperature cell performance with high coulombic efficiency was successfully obtained.