High-Performance Flow Battery with Inexpensive Inorganic Reactants

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East Hartford, Connecticut
Project Term:
01/23/2019 - 05/31/2022

Critical Need:

Stationary electrical energy storage plays several important roles in the U.S. electricity system, and these are expected to grow as the grid continues to evolve. Long-duration energy storage systems address grid needs beyond those covered by daily cycling. Such systems could provide backup power for several days, improving grid resiliency, or allow for the integration of even larger amounts of intermittent renewable sources like wind and solar. In the near term, such systems could help shape the output from individual wind and solar installations, improving the reliability of these resources and thus greatly increasing their value to the grid.

Project Innovation + Advantages:

The United Technologies Research Center team will develop an energy storage system based on a new flow battery chemistry using inexpensive and readily available sulfur and manganese based active materials. The team will employ innovative strategies to overcome challenges of system control and unwanted crossover of active materials through the membrane. The affordable reactants, paired with the unique requirements for long-duration electricity discharge, present the opportunity for very low cost energy storage.

Potential Impact:

If successful, DAYS projects will provide new forms of long-duration stationary electricity storage systems that enhance grid resiliency, provide low-cost energy capacity, support grid infrastructure, and enable a greater share of intermittent renewable resources in the generation mix.


Long-duration storage can help prevent blackouts and smooth overall grid operation, improving resilience and enhancing grid security.


New, extended storage options could enable greater integration of intermittent renewable energy sources, greatly reducing emissions from the power sector.


Energy storage technologies could help improve grid efficiency and promote the growth of domestic renewable energy sources.


ARPA-E Program Director:
Dr. Halle Cheeseman
Project Contact:
James Saraidaridis
Press and General Inquiries Email:
Project Contact Email:


University of Colorado, Boulder
Lawrence Berkeley National Laboratory
Massachusetts Institute of Technology
Pennsylvania State University

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