Flow Battery Structures to Improve Performance and Reduce Manufacturing Cost

Redox flow batteries are a promising technology for electrical energy storage for renewable energy sources; however traditional redox flow batteries are limited in their use due to non-uniform pressure drops and mass transfer limitations, as well as high manufacturing costs related to the felt material costs for the electrode and component alignment challenges during manufacturing.General Statement of How this Problem is Being Addressed The program objective is to validate alpha/beta scale manufacturing of redox flow battery components with greater power/energy densities while substantially reducing stack components and associated manufacturing costs compared to current flow battery technology. By replacing the traditional felt electrode material with electrodes coupled with thin metallic bipolar plates that utilize specially engineered structures such as arrays of posts, pyramids and/or pillars, acceptable pressure drops can be realized while increasing reactant mass transfer rates, eliminating costs associated with the felt and component alignment.What was done in Phase I: Faraday and Case Western Reserve University utilized model electrode/bipolar plate structures to demonstrate manufacturing feasibility and simulation viability for a range of engineered feature sizes and limiting current densities in iron-iron flow battery tests. Flow battery bipolar plate structures that would yield a high limiting current density with acceptable pressure drop were identified, and will be fabricated in Phase II. Preliminary cost analyses showed that the electrode/bipolar plate components are cost-effective for a near-term low volume development market ($20-30 per plate) and a long-term high volume commercial market ($0.40 to $1.90 per plate).What is planned for the Phase II project: We will develop Design Rules and a Model for fabrication of electrode/bipolar plates for a range of flow battery chemistries and load leveling technologies. The initial test bed will be the Case iron hybrid battery, and subsequently we will work with a number of government and industrial collaborators for single-cell testing of their preferred chemistry, material and patterns. We will build an apparatus for limited rate initial production of plates for transition to Phase III commercial activities, and update our manufacturability/cost assessment. Commercial Applications and Other Benefits Improving the economics of redox flow batteries through reduced manufacturing costs could make them an attractive electrical energy storage system for traditional utilities, grid service providers and equipment suppliers. In addition, redox flow batteries can supplement renewable energy sources by storing power for delivery at peak demand. One potential specific market for economical redox flow batteries is in commercial buildings due to their large percentage of energy consumption.