A Digital Blueprint for 3D-Printing Lab Scale Aqueous and Organic Redox-Flow Batteries

Abstract

With the ongoing development of renewable energy, the need for large-scale energy storage or energy buffer systems is increasing simultaneously. By separating capacity (i.e. concentration and tank size) and voltage (i.e. electrochemistry of the redox-active species), redox-flow batteries (RFBs) offer an exciting opportunity to address these challenges. Due to the wide range of synthetic possibilities in organic and inorganic chemistry, the number of potential novel RAS or membranes, as well as the optimization of existing ones is constantly increasing. However, the high financial cost of lab scale RFB systems for basic research poses an entry hurdle for small synthesis groups, so that this basic research can either only be carried out by specialized groups or only approximate systems (e.g. H-cell assemblies or active material adsorbed on carbon nanotubes in coin-cells) can be investigated. A simple and cost-efficient lab scale RFB setup would thus be an essential step forward in pushing fundamental RFB research forward.With its cost-efficient and precise nature, additive manufacturing (3D printing) is a promising technique to overcome these challenges, as it has already found application in several other areas of battery research.Using this technique, we were able to create a design proposal for a lab scale RFB setup, consisting of the RFB cell itself, the tank and pump system, and an inert gas container for about 220€. We tested the system with both an aqueous electrolyte system and an organic one to investigate its versatility. We tested the system with both an aqueous electrolyte system (K4[FeII(CN)6]/K3[FeIII(CN)6]) and an organic one (Fc/FcBF4) to guarantee its applicability to both electrolyte systems. The goal is to use this template for 3D-printed RFB cell to facilitate independent practical RFB research by small research groups.