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Advanced Flow Battery Electrodes

Primus Power
ARPA-E Award: 
Hayward, CA
Project Term: 
09/01/2010 to 12/31/2012
Project Status: 
Technical Categories: 
Graphic of Primus Power's technology
Critical Need: 
Our national electric grid has limited ability to store excess energy, so electricity must constantly be over-generated to assure reliable supply. Though wind and solar power are promising clean alternatives to fossil fuels, their natural unpredictability and intermittency present major challenges to delivery of the consistent power that is necessary to operate today's grid. The U.S. needs technologies that can store renewable energy for future grid-use at any location. Flexible, large-scale storage would create a stronger and more robust electric grid by enabling renewables to contribute to reliable power generation.
Project Innovation + Advantages: 
Primus Power is developing zinc-based, rechargeable liquid flow batteries that could produce substantially more energy at lower cost than conventional batteries. A flow battery is similar to a conventional battery, except instead of storing its energy inside the cell it stores that energy for future use in chemicals that are kept in tanks that sit outside the cell. One of the most costly components in a flow battery is the electrode, where the electrochemical reactions actually occur. Primus Power is investigating and developing mixed-metal materials for their electrodes that could ultimately reduce the lifetime cost of flow batteries because they are more durable and long-lasting than electrodes found in traditional batteries. Using these electrodes, Primus Power's flow batteries can be grouped together into robust, containerized storage pods for use by utilities, renewable energy developers, businesses, and campuses.
Potential Impact: 
If successful, Primus Power's highly durable advanced metal electrodes would reduce the cost of flow batteries while providing greater lifetime and energy density than current-generation technologies, enabling rapid deployment of stored energy to the electric grid.
A more efficient and reliable grid would be more resilient to potential disruptions.
Electricity generation accounts for over 40% of U.S. carbon dioxide (CO2) emissions. Enabling large-scale contributions of wind and solar power for our electricity generation would result in a substantial decrease in CO2 emissions.
Increases in the availability of wind and solar power would reduce fossil fuel demand, resulting in reduced fuel prices and more stable electricity rates.
Innovation Update: 
(As of May 2016)
Leveraging its innovative, long-life electrode, Primus Power has developed a commercially available flow battery that comes in a modular 25 kW / 125 kWh system for grid-level storage. As of 2016, Primus has delivered about 20 battery systems, and in September 2015, the company announced that a major Asian utility has ordered 1,250 batteries. A Primus battery is also an integral part of a microgrid in testing at the U.S. Marine Corps Air Station in Miramar, California. Additionally, a California-based industrial facility uses the Primus battery to manage electricity costs (i.e. the system stores power when electricity rates are low and discharges it when rates are high). In total, Primus has raised more than $60M in private funding since 2009 to help advance it’s commercial and technical development. 
During the team’s ARPA-E award, Primus’ core objective was to develop an electrode that could extend system lifetime and reduce costs for flow batteries. The team replaced the standard carbon-base for electrodes with a new structure based on a metal substrate and structured mixed-metal catalyst, which enhanced the electrode’s resiliency and electrical conductivity. The team then experimented with various flow-battery chemistries and ultimately determined that a Zinc-Bromine (Zn-Br) chemistry worked best with its electrode. The resulting flow cell delivers 5x higher stack power than previous commercial Zn-Br flow batteries and its cycle life is 8x longer. 
For a detailed assessment of the Primus team's project and impact, please click here.

ARPA-E Program Director: 
Dr. Mark Johnson
Project Contact: 
Mr. Rick Winter
Release Date: