PVDF/Graphene Composite Nanoporous Membranes for Vanadium Flow Batteries

Abstract

The development of chemically stable and high conductive membranes is one of the most important issues to improve the performance of vanadium flow batteries (VFBs). Herein, poly(vinylidene fluoride) (PVDF)/graphene composite nanoporous membranes were easily fabricated by manipulating crystallization processes. The graphene was used to enhance membrane selectivity and conductivity. In the nanoscale channels of the membranes, the graphene nanosheets reduced the apertures among the crystal grains, thus restraining vanadium ions crossover due to the size exclusion effect. Moreover, the oxygen groups on the graphene improved the surface hydrophilicity and formed hydrogen bonds with the PVDF polymer chains, which facilitated the proton transport. The composite membranes, with a 0.15 wt % graphene loading, showed a selectivity of 38.2 and conductivity of 37.1 mS/cm. The single cell exhibited a coulomb efficiency of 94.7%, a voltage efficiency of 88.5%, and an energy efficiency of 83.8%, which was 13% higher than that of the pristine PVDF membranes. The composite membranes showed excellent stability during 100 charge-discharge cycles. All these results indicate that the PVDF/graphene composite membrane is a promising candidate for VFB applications.

Free-Standing PVDF/Reduced Graphene Oxide Film for All-Solid-State Flexible Supercapacitors towards Self-Powered Systems

“…The energy-dispersive X-ray spectroscopy (EDS) spectrum reveals the reduced graphene oxide contains C:O in the ratio of 84.2:15.8 which is in agreement with the previous reports [43]. The FESEM micrograph shown in Figure 3C,D shows the low and high-resolution micrograph of the PVDF/reduced graphene oxide composite film with the uniform distribution of the reduced graphene oxide in the PVDF composite [44]. Besides, the elemental mapping analysis provided in Figure 3E-H also confirms the presence of carbon, oxygen, fluorine in the PVDF/reduced graphene oxide composite film.…”

Computational analysis of atomic binding energy for organosilicon‐ low‐density polyethylene‐coated silica embedded in polyvinylidene fluoride composite membrane for membrane gas absorption

“…After completing the modification of SiNP, these LDPE/f‐SiNP are added as inorganic additives to the membrane dope. As we all know, PVDF is stable, so its chain is unlikely to break, but there is evidence that it can form hydrogen bonds with surrounding molecules 39,40 . Therefore, to study the possibility of hydrogen bonding between PVDF and LDPE/f‐SiNPs, a HyperChem simulation was performed using PVDF in a periodic box containing water and ethanol.…”

Ion separations with membranes

“…That research inspired investigation of nanoporous membranes in VRFBs instead of cation-exchange membranes. [128][129][130][131][132][133][134][135] Particularly, a number of studies examined poly(benzimidazole) (PBI) membranes [136][137][138][139][140] and even advocated the use of PBI membranes for all VRFBs. [141] Pristine PBI membranes are nonporous and have low ionic conductivities.…”