Regulating Molecular Interactions in Polybenzimidazole Membrane for Efficient Vanadium Redox Flow Battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Polybenzimidazole (PBI) membranes exhibit poor proton conductivity due to their rigid structure, limiting their application in cost-effective vanadium redox flow batteries (VRFBs).
• A strategy is needed to relax the PBI membrane structure, enhancing proton conductivity while maintaining structural integrity.

Purpose of the Study:

• To propose a novel strategy for regulating molecular interactions within PBI membranes.
• To significantly enhance proton conductivity and improve the performance of PBI membranes in VRFBs.

Main Methods:

• Sequential treatment of PBI membranes with DMSO/water and acid solutions to alter molecular interactions.
• Characterization of membrane properties and performance evaluation in VRFB.

Main Results:

• Proton conductivity of the PBI membrane was enhanced by 3850% (from 1.9 to 76.3 mS/cm).
• The VRFB utilizing the enhanced PBI membrane achieved a high energy efficiency of 80.5% at 200 mA/cm².
• The study elucidated the structure-property relationship and the mechanism for enhanced proton conductivity.

Conclusions:

• The proposed strategy effectively loosens the PBI membrane structure, dramatically improving proton conductivity.
• The enhanced PBI membrane shows outstanding performance for VRFB applications.
• This work provides significant insights into PBI membrane development for advanced VRFB systems.