Small-Scale, Low-Cost Flow Cell Platform for Rapid Characterization of Redox Flow Battery Materials

Economic considerations are a primary driver to the adoption of redox flow battery (RFB) technology for grid storage. 1 Minimizing area-specific resistance of flow cells is critical to enabling efficient operation at high power, motivating research into redox electrolytes and cell designs. 2,3 The ability to effectively test small quantities of materials is essential, as early prototypes will likely require down-selection and refinement to meet desired performance. Further, identifying the causes of device failure can be challenging as they may be related to either materials degradation (e.g., instability, insolubility, incompatibility) or shortcomings in cell design (e.g., crossover, membrane degradation, high resistance). While established methods exist for quantifying electrochemical and transport properties under well-defined conditions and in isolation, translating this knowledge to laboratory-scale flow cells (and beyond) is nontrivial as experimental conditions are complex and results are often convoluted by other processes within the system. To this end, decoupling molecular discovery and engineering science is key: demonstrations of new active materials and design improvements require dedicated toolkits and testing protocols that enable robust comparative evaluations. 4 Thus, the development of broadly accessible research platforms, both hardware and software, may help advance scientific understanding and, ultimately, quicken technology growth. Here, we describe efforts to develop a small-scale (2.55 cm 2 ), low-cost flow cell for screening of RFB component materials. Modeled on and validated against state-of-the-art vanadium RFB designs, the small volumes and chemical resistance of the prototype enables evaluation of a wide range of chemistries with minimal materials requirements (e.g., active materials, membranes). In this presentation, we will discuss the key features of this platform, highlight its utility via representative materials design campaigns, and propose future applications of potential scientific and technological value. Ultimately, the aim of this flow cell is to accelerate progress by enabling rapid turnaround (i.e., fail fast) and easing entry into the field of a diverse set of researchers with key subdomain expertise. In this spirit, detailed flow cell designs, bills of material, standard operating procedures, and validation sets are made freely available to the research community to enable internal assessment and potential adop