The Iron-Age of Storage Batteries: Techno-Economic Promises and Challenges

In this article, we explore the techno-economic promises and challenges related to iron electrode systems, specifically in the iron-air system. We study the discharge-charge products of an iron-air system in an aqueous electrolyte using an iron-water Pourbaix diagram. Using the discharge-charge products from the Pourbaix analysis, we construct a proposed baseline iron-air cell to estimate the basic voltage and capacity of the cell. This cell is then assembled into a battery pack to analyze the unit cost of a 150-hour iron-air system using a process-based cost model developed from the BatPaC model. With the appropriate choice of materials for an iron-air system, we estimate the total battery pack system cost for iron-air to be about US$25/kWh where the cell material costs are around US$5/kWh. The pack hardware costs, air delivery system, and manufacturing costs together account for over US$20/kWh. Through further engineering improvements, better catalysts, and cell chemistry improvements, the battery pack costs may be reduced further, which is promising for long-duration storage applications.