Hydrophobic asymmetric ultrafiltration PVDF membranes: an alternative separator for VFB with excellent stability

Abstract

Polyvinylidene fluoride (PVDF) ultrafiltration membranes were investigated for the first time in vanadium redox flow battery (VFB) applications. Surprisingly, PVDF ultrafiltration membranes with hydrophobic pore walls and relatively large pore sizes of several tens of nanometers proved able to separate vanadium ions and protons efficiently, thus being suitable as a VFB separator. The ion selectivity of this new type of VFB membrane could be tuned readily by controlling the membrane morphology via changes in the composition of the membrane casting solution, and the casting thickness. The results showed that the PVDF membranes offered good performances and excellent stability in VFB applications, where it could, performance-wise, truly substitute Nafion in VFB applications, but at a much lower cost.

Effect of the graphitization degree for electrospun carbon nanofibers on their electrochemical activity towards VO2+/VO2+ redox couple

“…Just because of the specific characteristics of VRFB, the electrolytes, membrane, electrode in addition to the cell structure influence the battery performance jointly, especially for the former two determine the battery cost to a great extent [2]. Up to know, plenty of researchers devote themselves to the improvement in the membrane and electrolytes [3][4][5][6], and some of achievements have been successfully generalized in the engineering application of VRFB. However, as the continuous improvements in the membrane and electrolyte of VRFB, it is found that the relatively poor electrochemical activity of CF or GF seriously limited the electrochemical performance of VRFB, and the improvement in the electrochemical activity of electrode becomes an important problem worried to be solved [7][8].…”

Synthesis of nanoporous PVDF membranes by controllable crystallization for selective proton permeation

“…A few researchers have reported primary investigations into the use of porous membranes to separate protons and vanadium ions for VFB applications [10][11][12][13]. The pore structures of these porous membranes were mainly irregular finger-like or spongy micropores that were formed through conventional phase-inversion processes.…”

Pulsating electrolyte flow in a full vanadium redox battery

“…One of the major advantages VRBs offer over other flow batteries with different chemistries is their resistance to electrolyte cross-contamination, giving them a theoretically infinite lifespan. First pioneered by Skyllas-Kazacos at the University of New South Wales [1e3], research has mainly focused on electrode [4e9], electrolyte [10e12] and membrane treatment [13,14] in order to achieve high energy efficiencies.…”