Power-efficient energy storage is important for the successful integration of renewables into the electrical grid, and one promising storage device is the redox flow battery. In this presentation, we discuss the design of the flow field component of a redox flow battery using topology optimization. The flow field is a flow manifold that distributes and guides fluid with reactant both into and out of the reactive porous electrode. The popular two-dimensional interdigitated flow field, where a series of interlocking flow channels force fluid into the electrode, is a design that is commonly used in the lab, and we perform our optimization to improve upon this design. Specifically, we aim to minimize the electrical and flow pressure power losses, and we find that different operating conditions, i.e., flow rate and current density, lead to different optimal designs. We observe fully three-dimensional features in our optimized designs, where primary flow channels appear along with smaller branching channels that guide fluid to the electrode. This provides evidence that three-dimensional structures can provide improvement over conventional two-dimensional designs. While high power efficiency can certainly be attained using a traditional interdigitated flow field, the dimensions of the fluid channels and solid lands need to be carefully chosen for the desired operating conditions. In this presentation, we show that our method can computationally guide this design process.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL release number: LLNL-ABS-830167.