Highly multiscale structural Poly(vinylidene fluoridehexafluoropropylene) / poly-m-phenyleneisophthalamide separator with enhanced interface compatibility and uniform lithium-ion flux distribution for dendrite-proof lithium-metal batteries

Abstract

In this paper, a novel multiscale structural poly(vinylidene fluoridehExafluoropropyl-ene) (PVDF-HFP)/poly-m-phenyleneisophthalamide (PMIA)-based gel polymer electrolyte (GPE) including tetrabutylammonium hexafluorophosphate (TBAHP) was prepared for lithium-metal batteries via electrospinning technology. Under the synergistic regulation of PVDF-HFP and TBAHP, the TBAHP/PVDF-HFP-PMIA (T/F-P) membrane was yielded distinct multiscale structure accompanied by extremely high porosity, reduced aperture and well-distributed pore structure, leading to exceedingly good electrolyte affinity and enhanced interfacial compatibility. Especially, the homogeneous lithium-ions flux distribution above lithium electrodes from the multiscale structure confinement could account for the uniform lithium nucleation and nondendrite growth. Meanwhile, the as-fabricated T/F-P separator exhibited admirable thermal stability and ultra-strong tensile strength, which also contributed to the inhibition of lithium dendrites and guarantee of battery safety. More significantly, the lithium/LCO (Li/LCO) cell with T/F-P separator obtained a pronounced improvement in cycle stability and rate capability thanks to the outstanding ionic conductivity, inferior interface impedance and reduced polarization. Moreover, the T/F-P-based lithium-sulfur (Li–S) battery also delivered the superior cycle performance due to prominent anti-self-discharge capability and forceful adsorption or captured ability to dissolved polysulfide species. Consequently, the highly multiscale structural T/F-P separator can be identified as a dependable candidate for the enhanced safety and electrochemical performance of lithium-metal cells.