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Clean energy solutions

Core Innovation

The Vanadium Redox Flow Battery (VFRB) was invented in 1986 by Dr. Maria Skyllas-Kazacos at UNSW in Australia. VRFB technology is considered the ultimate energy storage method available with the highest lifetime efficiency. VRFB’s are modular and can be customized to build capacities ranging from 20-kilowatt hour to several megawatt-hour. XRG’s vanadium redox battery system stores energy in liquid vanadium electrolyte (both the anolyte and catholyte) that never degrades. Hardware can be recycled and the vanadium electrolyte (up to 80% of the VRFB) can be reused indefinitely compared to lead-acid, lithium-ion, and other battery systems.

XRG’s ultimate goal is to become a leading provider of sustainable energy storage technology. The ability to reutilize the vanadium catholyte and anolyte in subsequent VRFB installations allow the potential for installed vanadium capacity to grow and costs to decrease further.

VRFB 101

The VRFB is a type of rechargeable flow battery where rechargeability is provided by vanadium electrolyte (VE) dissolved in solution. The two tanks of Vanadium, one side containing V2+ and V3+ ions, the other side containing V4+ and V5+ ions, are separated by a thin proton exchange membrane.  VRFBs consists of two tanks of vanadium electrolyte that flow adjacent to each other past a membrane and generate a charge by moving electrons back and forth during charging and discharging. This battery offers unlimited energy capacity simply by using larger electrolyte storage tanks. It can be left completely charged for long periods without losing power and maintenance is much simpler than other batteries. Pumps on both sides circulate the electrolyte.

The electron differential between the two cells generates electric power. Most batteries use two chemicals that change valence (or charge or redox state) and cross-contaminate and thus degrade over time. VRFBs utilize multiple valence states of vanadium as a single element to store and release charge. The VRFB has no cross-contamination like most batteries. The electrolyte in the catholyte and the anolyte consists of 100% vanadium ions. The ion-sensitive membrane separating both sides of the electrolyte tank allows only protons to pass. VRFBs are containerized, long duration, non-flammable, compact, reusable over infinite cycles and last more than 20 years. 

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