Sbir phase II: flow battery electrolyte purification: unlocking 24-hour storage potential

Otoro Energy Inc. received a $1.21M Phase II Cooperative Agreement from the National Science Foundation (NSF) under the Technology, Innovation, and Partnerships program (CFDA 47.084), effective September 1, 2025, through August 31, 2027. The award supports the development and full-scale deployment of a novel purification apparatus for a proprietary metal chelate flow battery (MCFB) system designed to enable cost-effective, long-duration energy storage for electric grid applications. The core deliverable is a reusable, low-cost purification process that removes trace metal impurities from liquid electrolytes, thereby mitigating catalyzed side reactions that compromise battery efficiency and performance. The technology utilizes non-toxic, non-flammable, and non-corrosive materials, enabling safer deployment near critical infrastructure and in fire-prone regions.

The project is being performed in Boulder, Colorado, and builds upon Otoro Energy's prior Phase I SBIR award ($275K, January 2024) focused on battery chemistry development using domestically sourced minerals. Under this Phase II cooperative agreement, the company will advance a battery system targeting over 80% round-trip efficiency with a 10- to 24-hour storage duration. Complementary work conducted through a sub-grant with the University of Colorado includes parallel scaling of metal chelate flow battery electrolyte manufacturing, with specific objectives of producing 500 liters of electrolyte and testing a 5 kilowatt/20 kilowatt-hour grid-connected system. These deliverables directly address the Department of Energy's forecasted need for 460 gigawatts of long-duration energy storage capacity by 2050, representing significant commercial potential for electric utilities and industrial users such as data centers.

Abstract

The broader/commercial impact of this small business innovation research (SBIR) phase II project is to enable cost-effective, long-duration energy storage, which is critical to ensuring a reliable electric grid. As demand for electricity is expected to soar in the coming years, grid operators require storage systems that can operate for 10 to 24+ hours to balance the supply and demand for power and ensure resiliency. The department of energy forecasts that the united states' grid may need 460 gigawatts (GWS) of long-duration energy storage capacity by 2050, representing $330 billion in cumulative capital. This investment would result in $20 billion in annualized savings in operating costs and avoided capital expenditures. The innovation supported by this project has the potential to serve a significant portion of this market, particularly among electric utilities and industrial users such as data centers. The technology is based on non-toxic, non-flammable, and non-corrosive materials, which allow for safer deployment near critical infrastructure and in fire-prone regions?enhancing energy access and resilience while avoiding the safety and environmental risks associated with current storage systems. In addition to economic and environmental benefits, the project may contribute to broader societal impacts by supporting domestic manufacturing and supply chains and increasing public confidence in energy infrastructure. The intellectual merit of this project centers on the development of a full-scale purification apparatus for a proprietary low-cost, high efficiency, non-flammable, scalable flow battery system. In metal chelate flow batteries (MCFBS), trace metal impurities within the liquid electrolytes can catalyze side reactions that compromise battery efficiency and long-term performance. This project proposes a novel, reusable, and low-cost purification process that removes these impurities, enabling the use of lower-grade input materials without sacrificing stability. The phase II objectives include: (1) validating the purification process at 24-hour discharge durations, (2) constructing a full-scale purification system, (3) building a grid-scale mcfb unit to test the electrolyte purified by this system, and (4) demonstrating 24-hour discharge battery performance using the integrated purification enhanced system. The outcomes of this project will advance the commercial readiness of the mcfb platform by enabling cost-effective electrolyte purification and enhancing system longevity?key enablers for widespread deployment of long-duration energy storage. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the foundation's intellectual merit and broader impacts review criteria.- subawards are not planned for this award.