PVDF/TiO₂/graphene oxide composite nanofiber membranes serving as separators in lithium‐ion batteries

Abstract

Improving the electrochemical properties of membranes in lithium‐ion batteries (LIBs) is very important. Many attempts have been made to optimize ionic conductivity of membranes. The aim of this study was fabricating composite nanofiber membranes of poly(vinylidene fluoride) (PVDF), containing titanium dioxide (TiO2) and graphene oxide (GO) nanoparticles to use in LIBs as separators. The morphology, crystallinity, porosity, pore size, electrolyte uptake, ionic conductivity, and electrochemical stability of the membranes were investigated using scanning electron microscopy, wide‐angle X‐ray diffraction, Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy, and linear sweep voltammetry. The electrolyte uptake and ionic conductivity of the PVDF/TiO2/GO composite nanofiber membranes containing 2 wt % GO were 494% and 4.87 mS cm−1, respectively, which were higher than those of the other fabricated membranes as well as the commercial Celgard membrane. This could be attributed to the increased porosity, larger surface area, and higher amorphous regions of the PVDF/TiO2/GO composite nanofiber membranes as a result of the synergistic effects of the nanoparticles. In this work, suitable optimized membranes with greater electrochemical stability compared with the other membranes were presented. Also, it was demonstrated that the incorporation of the TiO2 and GO nanoparticles into the PVDF nanofiber membranes led to a porous structure where the electrolyte uptake enhanced. These properties made these membranes promising candidates for being used as separators in LIBs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48775.

Polymers for advanced lithium-ion batteries: State of the art and future needs on polymers for the different battery components

“…A discharge capacity of 95 mA•h• g -1 was observed at 8C, which contrast with the 67 mA•h• g -1 obtained using a commercial PP separator [295]. PVDF composites with TiO2/graphene oxide [296] and LiSnZr(PO4)3 [297] were developed as battery separators with the objective to increase the ionic conductivity. SiO2, ZrO2 and TiO2 particles have been also incorporated into microporous PVDF-HFP membranes via phase inversion method using deionized water as a non-solvent and acetone as solvent.…”

Safer Lithium‐Ion Batteries from the Separator Aspect: Development and Future Perspectives

“…GO has been employed as inorganic fillers by a phase inversion method or electrospinning to improve the thermal stability, mechanical strength, and ionic conductivity of separators. [ 93‐96 ] For instance, Choi et al. [ 92 ] incorporated GO nanosheets into the PVDF‐HFP skeleton during the pore generation process by phase inversion ( Figure a).…”

Recent Advances on Materials for Lithium-Ion Batteries

“…The ionic conduction of the separators is a direct consequence of their wettability and uptake, as the electrolyte plays a key role on the electrochemical properties of the system. In this regard, composite separators are intensively used, and different combinations of polymer matrix and specific fillers are being developed, such as, boehmite/polyacrylonitrile (BM/PAN) [219], 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) into polyacrylonitrile (PAN) [220], PVDF containing titanium dioxide (TiO 2 ) and graphene oxide (GO) [189], PVDF with 13X zeolite [195] and PVDF with modacrylic and SiO 2 [221], polyacrylonitrile (PAN)/helical carbon nanofibers(HCNFs)@PVDF/UiO-66 composite [222], cellulose/Poly (vinylidene fluoride-hexafluoropropylene) membrane with titania nanoparticles [202], polyimide (PI) with ZSM-5 zeolite as filler [190] and PVDF with titanium hydroxide (Ti(OH) x ) [223], polyethylene terephthalate (PET) combined with inorganic zirconia (ZrO 2 ) [224], silica-coated expanded polytetrafluoroethylene separator [225], poly(vinyl alcohol) (PVA) with ZrO 2 nanoparticles [226], poly(vinyl alcohol) (PVA) with submicron spindle-shaped CaCO 3 [227], poly(vinyl alcohol)/melamine composite nanofiber membrane containing LATP nanocrystals [228], and poly(m-phenylene isophthalamide) (PMIA) with SiO 2 nanoparticles [229], among others, mainly with the main focus on improving the electrochemical properties. In particular, separators based on PVDF coated with ZnO have been developed with higher ionic conductivity (2.261 mS•cm −1 ), high porosity (85.1%), favorable electrolyte wettability (352%), and lower interfacial impedance (220 Ω) [198].…”