Enhanced performance and reduced pumping loss in vanadium flow battery enabled by a leaf-vein-inspired flow field design

All-vanadium redox flow batteries hold promising potentials in large-scale energy storage. Flow field designs are effective ways to enhance their performance for operation at high power density. However, traditional intuitionbased designs remain limitations due to the insufficient mass transport and flow resistance in porous electrode. Inspired by the advantages of nature leaf in species transport and hydraulic characteristics, we conceived a novel leaf-vein flow field to simultaneously improve electrochemical performance and pumping loss. The new design significantly boosts the reactant mass transfer and lowers the pressure drop, which are attributed to the reduced distance of the electrolyte transport, the excellent spreading of the electrolyte caused by the bifurcated structure, and the reduced flow resistance. Moving outlet channels to the membrane side enables more uniform delivery of reactant and prevents localized reactant depletion. The new design also inherits strong survival competitiveness of nature leaf with a higher hydraulic conductivity, ensuring efficient water supply throughout the flow field without dead zones at relatively low hydraulic resistance. This work provides a potential way to regulate reactant distribution and diffusion distance by bionic flow field design, enabling both improvement in energy efficiency and pumping loss.