Sulfonated graphene oxide/nafion composite membrane for vanadium redox flow battery

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Nafion is a widely used membrane material in vanadium redox flow batteries (VRFBs) due to its high proton conductivity and stability.
• However, Nafion's inherent porous structure leads to poor barrier properties, resulting in high vanadium ion permeability.
• This limitation hinders the efficiency and performance of VRFBs.

Purpose of the Study:

• To develop novel composite membranes based on Nafion with enhanced barrier properties for VRFB applications.
• To investigate the synthesis and characterization of graphene oxide (GO) derivatives, specifically sulfonated GO (sGO), and their modified forms (isGO, iGO).
• To evaluate the performance of these modified Nafion composite membranes in terms of proton conductivity, vanadium permeability, and selectivity.

Main Methods:

• Graphene oxide (GO) was sulfonated to prepare sGO.
• Both sGO and GO were reacted with phenyl isocyanate to create isGO and iGO, respectively, to improve miscibility with Nafion.
• Composite membranes were fabricated by incorporating these modified GO derivatives into a Nafion matrix.
• Proton conductivity and vanadium permeability were measured to assess membrane performance for VRFBs.

Main Results:

• The isGO/Nafion and iGO/Nafion composite membranes demonstrated reduced temperature sensitivity in proton conductivity compared to pristine Nafion.
• Both modified membranes exhibited significantly lower vanadium permeability at room temperature.
• The isGO/Nafion membrane showed the highest selectivity, outperforming pristine Nafion and iGO/Nafion membranes.

Conclusions:

• Modified graphene oxide derivatives effectively enhance the barrier properties of Nafion composite membranes.
• The developed isGO/Nafion and iGO/Nafion membranes offer improved performance for vanadium redox flow battery applications.
• These findings suggest a promising pathway for creating advanced membranes with superior selectivity and stability for energy storage systems.