A perspective on the design and scale up of a novel redox flow battery

Abstract Government funding is critical for testing concepts and ideas of technical approaches to demonstrate their value to attract attention for commercial development. In the US for energy projects, this funding often comes from ARPA-E, but similar types of funding agencies exist in other countries as well. However, independent of the funding sources, government or private, often unanticipated challenges arise that require pivots and flexibility, and leap-frogging scale-up levels can hinder achieving the knowledge needed for technology development. By incorporating a conducting carbon slurry in the negative electrolyte of an all iron flow battery, the decoupling of power from energy design becomes possible for this normally hybrid flow battery system. This approach offers the potential for very low cost large-scale energy storage with safe and sustainable materials. Government funding of this project allowed the demonstration of the concept during the seedling stage, but with the use of carbon nanotubes that would not meet cost targets. The second phase of the project demonstrated that low cost carbons with certain properties could also be used effectively. The third phase of the project then sought to scale-up the lab cells to a full-size stack. This paper summarizes some of the technical challenges encountered and pivots in approach that were taken. This project was sponsored by a commercialization-focused government agency (US ARPA-E in this case) and we point out some constraints and expectations of attracting commercial funding sources that hindered the development, or complicated solving the necessary design and materials issues to make the technology interesting for further investment. The lessons learned here will be applicable to other commercialization driven projects sponsored by government agencies in the US and elsewhere. Graphical abstract