APPLICATIONS OF TECHNOLOGY:
- Multi-hour power delivery for grid scale energy storage
- Renewable energy storage in buildings
- Backup power for critical infrastructure in locations with poor grid reliability
- Energy storage for nano and microgrids powering off-grid sites
- Long cycle life
- Low cost
- Improved rate capability
A team of researchers at Berkeley Lab led by Brett A. Helms developed a technology optimizing all-organic redox flow batteries by pairing redox-active oligomeric organic molecules and size-selective porous polymer membranes that block the crossover of active molecules and allow the movement of supporting ions in solution. The Berkeley Lab technology also uses small (relative to polymers) molecules that keep the solution viscosity and electron transfer kinetics low and fast.
All organic redox-flow batteries are well positioned to offer low cost, multiple hour electrochemical energy storage at large scale in line with targets for grid modernization and areas with poor grid reliability. However, most redox-flow batteries are plagued by the crossover of active materials, which leads to decreased cell efficiency and cycle life. Some previous attempts to remedy this issue led to decreased membrane ionic conductivity, reducing the rate capability of the cell. Other remedies, such as the use of large polymeric charge storage molecules, resulted in improved crossover performance but increased solution viscosity (which increases pumping losses) and decreased electron transfer kinetics. The Berkeley Lab technology overcomes these limitations for lower cost, more efficient energy storage devices with better rates capability and longer cycle life.
The technology provides an important counter to single component electrodes paired with ceramic membranes, which are expensive and difficult to scale; thick macroporous separators paired with mixed electrode formulations, which lead to Coulombic and voltage inefficiencies; and mesoporous separators paired with redox-active polymers, which can be difficult to pump through electrochemical cells at high molecular weight and at all states of charge.
FOR MORE INFORMATION:
Doris, S., Ward, A., Baskin, A., Frischmann, P., Gavvalapalli, N., Chenard, E., Sevov, C., Prendergast, D., Moore, J., Helms, B. “Macromolecular Design Strategies for Preventing Active-Material Crossover in Non-Aqueous All-organic Redox-Flow Batteries,” Angew. Chem. Int. Ed. 2017, 56, 1595-1599.
DEVELOPMENT STAGE: Proven principle. Sample materials had more than 100 times slower crossover of oligomer through selective membrane than with existing commercial membranes.
STATUS: Published U. S. Patent Application 15/606,961 (Publication US2017-0346104). Available for licensing or collaborative research.
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