Organized macro-scale membrane size reduction in vanadium redox flow batteries: part 2. Flow-field-informed membrane coverage distribution

Abstract

Membranes are a critical component in flowing-electrolyte electrochemical systems like redox flow batteries (RFB), and as such, they contribute significantly to overall RFB stack cost which affects technology adoption. We explore flow-field-informed membrane coverage distribution in this part of the series. Where membrane coverage distribution is specifically informed by the relative positions of the ‘channel’ and ‘land’ in the adopted flow-field design – towards cell/stack cost reduction with minimal compromise in power and efficiency. Simulated performance comparison of a Vanadium RFB cell in 3D with membrane-electrode assemblies (MEA) having full membrane coverage and channel/land-adjacent membrane coverage reductions showed the promise of channel-adjacent membrane coverage reduction across all evaluated flow-field designs. We found that the membrane coverage can be reduced by up to 20% (adjacent to the flow-field channel), with simulations showing less than 1% compromise in power compared to full membrane coverage MEA. We also observed that the prevalent flow-field-informed membrane coverage distribution further influences the spatial variation of electrochemical activity within the cell, consequently being a potential tool to inform cell thermal management.