Novel sulfonated poly(ether ether ketone)/triphenylamine hybrid membrane for vanadium redox flow battery applications

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Sulfonated poly(ether ether ketone) (SPEEK) membranes are crucial for vanadium redox flow batteries (VRFBs).
• Enhancing ion selectivity and reducing vanadium permeability in SPEEK membranes remain key challenges for VRFB performance.

Purpose of the Study:

• To fabricate and characterize novel sulfonated poly(ether ether ketone)/triphenylamine (SPEEK/TPAM) hybrid membranes.
• To investigate the effect of varying triphenylamine (TPAM) loadings on membrane properties and VRFB performance.
• To evaluate the potential of these hybrid membranes as alternatives to conventional VRFB membranes like Nafion115.

Main Methods:

• Fabrication of SPEEK/TPAM hybrid membranes with 1%, 2%, and 5% TPAM loadings.
• Characterization of physicochemical properties, morphology, vanadium permeability, and proton conductivity.
• Performance evaluation of the optimized SPEEK/TPAM membrane in a VRFB single cell setup.

Main Results:

• The hybrid membranes exhibited lower vanadium permeability compared to pristine SPEEK membranes due to acid-base interactions.
• Triphenylamine incorporation improved proton conductivity by facilitating proton transfer through protonated nitrogen atoms.
• The SPEEK/TPAM-1% membrane demonstrated superior ion selectivity over SPEEK and Nafion115 membranes.
• A VRFB single cell using the SPEEK/TPAM-1% membrane showed enhanced performance compared to Nafion115 at 60 mA cm⁻².

Conclusions:

• The novel SPEEK/TPAM hybrid membranes offer a promising pathway to overcome limitations of conventional VRFB membranes.
• Optimized triphenylamine loading significantly enhances membrane properties for efficient VRFB operation.
• SPEEK/TPAM hybrid membranes show great potential for practical application in vanadium redox flow batteries.