Rapid Discovery and Optimization of Unitized Reversible Fuel Cell Catalysts

Long-duration energy storage technologies are required to overcome intermittency challenges with the increasingly renewable grid. Reversible fuel cells, which store energy in the form of hydrogen via water electrolysis, and produce energy from hydrogen fuel, present an attractive solution to the long-term energy storage problem; unitized eversible fuel cells, which combine a fuel cell and an electrolyzer into one system that can operate in both charging (electrolyzer) and discharging (fuel cell) modes, minimize capital costs and footprint, yet are currently lacking in overall efficiency. This project is focused on the development and optimization of catalyst materials for unitized reversible fuel cells, which are the largest contributors to the lack of efficiency within unitized reversible fuel cells. Using Mattiqĺs end-to-end catalyst development pipeline, which has been demonstrated in the context of water splitting catalyst development, optimal bi-functional cathode and anode catalysts will be discovered using ultrahigh-throughput catalyst discovery technologies, and then scaled and validated in prototype-scale reversible fuel cells. More specifically, in Phase I Mattiq developed the capabilities to screen catalyst libraries for their bi-functionality in the context of unitized reversible fuel cell cathode catalysts at highthroughput. Leveraging these capabilities, Mattiq will complete Phase I by performing a broad search for the most active and durable cathode catalysts with minimal precious metal content. In Phase II, Mattiq will accomplish the following: (1) perform a similar broad search for optimal anode catalysts using the methodologies developed in Phase I, (2) scale-up the most promising cathode catalysts identified in Phase I and compare their performance relative to state-of-the-art catalyst materials, (3) scale-up the most promising anode catalysts identified in Phase II and compare their performance relative to state-of-the-art catalyst materials, and (4) combine the optimized cathode and anode catalyst materials for long-duration testing, with the aim of reaching Department of Energy 2030 performance targets for low-temperature reversible fuel cells (>55% roundtrip efficiency, <1 mg of precious metals per cm2, and <0.25% loss per 1,000 hrs). If successful, this project can lead to new products within the burgeoning ĹHydrogen Economy.ĺ Efficient unitized reversible fuel cells present an intriguing low capital cost alternative to discrete reversible fuel cells (separate fuel cell + electrolyzer) that performs comparably to each component individually. Further scale-up, manufacturing optimization, and field validation in Phase III would ultimately lead to a unitized reversible fuel cell that can efficiently store excess renewable energy over long durations.