Parasitic hydrogen bubble evolution in vanadium redox flow batteries: A lattice Boltzmann study

Vanadium redox flow batteries (VRFBs) are a promising technology to capture and store energy from renewable sources, reducing the reliance on fossil fuels for energy generation. However, during the charging process, the parasitic hydrogen evolution reaction at the negative electrode affects the performance and durability of VFRBs. The evolution of hydrogen bubbles causes the loss of effective reaction area and blocks the transport of reactants. We employ the lattice Boltzmann method to investigate the two-phase flow transport in the negative electrode of VRFBs. Systematic parametric analyses reveal that increased gas production leads to uneven gas removal from the electrode, while an optimal flow rate can effectively remove bubbles and reduce external pumping energy. Additionally, increasing the compression ratio hinders gas removal but enhances electrode electrical conductivity. Overall, the present study provides valuable mechanistic insights into bubble generation at the negative electrode of VRFBs and offers a theoretical reference for designing and optimizing VRFBs.