Towards Low Cost and Long Duration Iron-Air Flow Batteries

Abstract

The electrification of the energy economy necessitates the development of low cost and large scale energy storage technologies that can integrate intermittent renewables (e.g. solar and wind). Among the various technological options (e.g. lithium ion batteries, vanadium redox flow batteries), metal-air batteries are promising alternatives owing to their high energy density, safety, and use of abundant raw materials. Moreover, when combined with the principles of redox flow batteries, mass transfer is enhanced, which results in a more uniform metal deposition and a reduction in the metal electrode passivation [2]. Furthermore, metal-air flow batteries could enable decoupling of power and energy, while retaining the scalability advantages of redox flow batteries. Additionally, they are more compact than conventional redox flow batteries since only one electrolyte tank is needed.Several metal-air flow battery systems have been investigated such as vanadium-air [3], lithium-air [4] and zinc-air batteries [5]. However, they suffer from limitations which challenge their scalability. Specifically, vanadium is costly and only available in certain regions, lithium requires the use of organic solvents which compromises the battery safety, and zinc forms dendrites leading to a lower performance and safety issues. In this context, iron-based batteries are a promising alternative due to their high specific capacity, low cost, large availability, safety, non-toxicity, and recyclability. Compared to zinc, iron is also less prone to dendrite formation during cycling in aqueous electrolytes since iron deposition kinetics is slower[6]. Despite these advantages, the performance of the iron anode is limited by electrode degradation during cycling due to phase transformations, hydrogen evolution, and low utilization of the activate material [6], which motivates fundamental research to advance the performance and durability of the system.In this poster presentation, we will discuss the main goals of our new project FAIR-RFB [7]. Our overall aim is to develop a low cost and durable iron-air flow battery system and, to this goal, we will investigate, (i) the role of porous electrode microstructure in defining the performance of iron-air flow batteries, (ii) the influence of electrode surface properties in determining transport phenomena, kinetics, selectivity and durability, and (iii) new electrochemical reactor architectures for high power iron-air redox flow batteries.