An Economical Composite Membrane with High Ion Selectivity for Vanadium Flow Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Nafion membranes, standard in vanadium flow batteries (VFBs), are expensive and allow high vanadium ion permeability.
• These limitations hinder the widespread commercialization and efficiency of VFBs.

Purpose of the Study:

• To develop a cost-effective composite membrane for VFBs.
• To enhance ion selectivity and reduce vanadium ion penetration.

Main Methods:

• Fabrication of a thin composite membrane using a low-cost microporous polyethylene (PE) substrate and perfluorosulfonic acid (PFSA) resin.
• Evaluation of the membrane's performance in a VFB, including coulombic efficiency and energy efficiency over cycling.

Main Results:

• The PE/PFSA composite membrane demonstrated superior ion selectivity compared to commercial Nafion212.
• VFBs utilizing the PE/PFSA membrane achieved high coulombic efficiency (approximately 96.8%) at 200 mA cm⁻².
• The membrane maintained stable energy efficiency over 200 cycles with minimal decay.

Conclusions:

• The developed PE/PFSA composite membrane offers a promising, low-cost solution for VFB applications.
• Its high ion selectivity and stable performance address key limitations of current VFB membranes.
• This membrane is an ideal candidate for advancing VFB technology.