Recent understanding on pore scale mass transfer phenomena of flow batteries: Theoretical simulation and experimental visualization

The performance of flow batteries is critically influenced by mass, ion, and electron transport processes and electrochemical reactions within the heterogenous porous electrodes. Understanding these processes at the pore scale is essential because it is at this level that the fundamental mechanisms governing transport and reaction dynamics occur. However, investigating pore scale mass transfer phenomena presents significant challenges, including the complexity of resolving intricate pore geometries of electrodes and the opaque nature of the flow cells, which hinders in-operando visualization. This mini review aims to summarize recent advances in numerical modeling and experimental visualization of pore scale mass transfer phenomena in flow batteries. By highlighting the importance of pore scale insights, we provide key findings and propose future research directions that focus on advancing pore scale modeling and developing innovative experimental methods to achieve a deeper understanding of pore scale transport phenomena, which are vital for next-generation electrode designs.