New research on redox flow batteries has identified improvements that can increase their capacity store wind and solar energy. Image Credit: Flickr user Gerry Machen
As the threat of climate change increases, interest in renewable energy technologies like solar power and wind power are on the rise. However, the growth of these renewable sources has been continually hampered by one fundamental problem: How to store the energy when the sun is not shining or the wind is not blowing. Right now, after renewable energy is generated, it must be used immediately, sold back to the grid or stored in a battery. But the most commonly used batteries on the market—deep-cycle lead batteries and lithium ion batteries—are not always compatible with the grid. They tend to work better for small, off-grid systems,1 which are not feasible or affordable for most energy users in the United States.
Enter redox batteries, which utilize more grid-compatible technology and have the potential to greatly expand renewable energy accessibility in the future, especially with recent developments in computational software. Although these are beset by their own problems, researchers at the University of Utah, the University of Michigan and the U.S. Department of Energy recently teamed up to start looking for ways to improve the technology. The results of their project, which were published in the Journal of the American Chemical Society in February 2017, present a preliminary solution and lay the groundwork for further research in the field.
Understanding the Benefits and Challenges of Using Redox Flow Batteries to Store Energy
The setup of redox flow batteries is different from that of traditional batteries. Redox flow batteries consist of two tanks of electrolytes: anolytes, which store negative charge, and catholytes, which store positive charge. They are separated by a set of inert electrodes. The electrolytes in the tanks hold the charge when electricity is not being used, and when it is time to release energy, they are pumped through the cell and the battery is discharged.2
However, the fundamental properties of vanadium, the molecule that is currently used to store charge, have kept redox flow batteries on the fringes of the renewable energy market. These hurdles include:
- Cost. Vanadium is expensive. For success on the market, the electrolytes used for redox flow batteries need to be low-cost so that they will be accessible for a wide range of consumers.
- Safety. Due to its potential toxicity, vanadium needs to be handled carefully. Not only is this inconvenient, but it also increases costs associated with renewable energy.
- Stability. Perhaps the most important factor slowing redox flow batteries’ entry into the mainstream renewables market is that it decomposes and loses charge rapidly, so it is insufficient for long-term energy storage.3
Identifying New Molecules for Use in Redox Flow Batteries
Given the problems associated with vanadium, the researchers at Utah, Michigan and the DOE set out to find a better molecule in order to improve redox batteries. Their first step was identifying compounds that were more stable than vanadium. To solve this problem, they used a computational method to screen libraries of compounds to identify the top candidates for further study. Using this method, they were able to identify less costly, less toxic anloyte candidates like pyridinium, which could be modified to increase their stability.4
Their findings set the stage for further research in this area. For instance, specialty chemicals developers can look for anolytes that last even longer and cost even less. In addition, it will be necessary to identify similar catholytes that can be used to make redox flow batteries more marketable. In order to develop such chemicals, researchers can use modern software that allows them to study candidate electrolytes in silico and make the molecular tweaks necessary to prevent interactions, in order to increase their stability.
Balancing Stability With Redox Potential
It is important to note that pyridinium was not the longest-lasting molecule that the researchers identified. While they were able to find more stable alternatives, these candidates had relatively low redox potential. This means that, when specialty chemicals researchers start looking for new anolytes and catholytes, they need to find a balance between molecular stability and redox potential. With the predictive capabilities of modern software, they can run simulations on candidate compounds as they tweak them, which can help them optimize these two essential properties.
Supporting Collaborations in Different Scientific Fields
The researchers at Utah, Michigan and the DOE attribute the success of their search for ways to improve redox flow batteries to speed the transfer of information between chemists and engineers. Altering the structure of molecules to tailor their properties for specific purposes is commonly used by pharmaceutical chemists, but its is only just gaining traction in the field of materials engineering. Today’s software technologies support these essential scientific collaborations by streamlining sustainable innovation and minimizing the number of physical experiments a researcher has to do. That way, specialty chemical companies can more efficiently develop the best possible electrolytes to use in redox flow batteries, which could finally make widespread use of solar energy and wind energy a reality.
BIOVIA Materials Studio is a modeling and simulation environment that researchers can use to investigate molecular and atomic structures and predict their properties. It also supports collaborative science, allowing researchers to easily share their results. Contact us today for more information about how this software and our other offerings can help your research organization develop technologies that have the potential to revolutionize the renewable energy industry.
- “Lithium-Ion Batteries for Off-Grid Systems,” February 2013, https://www.homepower.com/articles/solar-electricity/equipment-products/lithium-ion-batteries-grid-systems?v=print ↩
- “Redox Flow Batteries,” 2017, http://energystorage.org/energy-storage/technologies/redox-flow-batteries ↩
- “Stabilizing Energy Storage,” February 21, 2017, https://www.sciencedaily.com/releases/2017/02/170221102034.htm ↩
- “Physical Organic Approach to Persistent, Cyclable, Low-Potential Electrolytes for Flow Battery Applications,” February 21, 2017, http://pubs.acs.org/doi/abs/10.1021/jacs.7b00147 ↩