Authors: Anton A. Nechaev, Gabriel Gonzalez, Prachi Verma, Vsevolod A. Peshkov, Anton Bannykh, Arsalan Hashemi, Jenna Hannonen, Andrea Hamza, Imre Pápai, Kari Laasonen, Pekka Peljo, & Petri M. Pihko
Journal: Chemistry: A European Journal
Year: 2024
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Vitamin B is commonly known as a nutrient that helps maintain a healthy immune system and a fully functioning metabolism. However, it can also play a surprising role in clean energy storage, a field of study which has become increasingly necessary as renewable energy sources like solar and wind become more technologically advanced and generate greater amounts of electrical energy. Key issues involved in using such technologies stem from the fact that they are intermittent energy sources, meaning they do not constantly and reliably produce power. For example, solar panels are only productive during the daytime and become less effective in cloudy conditions, and wind turbines are dependent on fluctuating and unpredictable wind speeds. As a result, renewable power sources may output too little energy during times of high demand (like in the evening when most people get home from work and turn on lights and appliances), or too much energy when demand is low.1 Such variability can be problematic for energy grid systems, as intermittent power delivery to a system can disrupt its stability and security.2
To address these issues of intermittency, electrochemical energy storage has been established as a way to support power grids. By storing surplus energy when renewable sources produce more power than needed and returning energy back into the power grid when renewable sources are unable to keep up with power needs, electrochemical energy storage helps balance the generation of and demand for electricity, allowing grid systems to operate more reliably.3 One of the most promising forms of such storage is the redox flow battery (Figure 1).
A redox flow battery (RFB) is a type of rechargeable battery that stores energy in liquid electrolytes, which are solutions of electrically conductive chemicals. These liquids are held in storage tanks and pumped through electrical conductors called electrodes. At these electrodes, the electrolytes engage in electron-transferring redox reactions that convert electrical energy to chemical energy to charge the battery, or vice versa to discharge it. A significant advantage of this design is that it can easily be scaled up for power grid applications—the power of the battery system can be boosted by increasing the size of the electrodes, and the storage capacity of the system can be improved by increasing the volume or concentration of electrolytes.4
Figure 1: Schematic of a redox flow battery. Reprinted with permission from Yang et al. Copyright © 2011, American Chemical Society.
RFBs have been successfully integrated into power grid systems, but not without some downsides. For example, vanadium redox flow batteries have been adopted at a commercial level due to their high durability, but the materials they use are expensive and toxic. Consequently, there has been a growing research interest in alternative RFBs that can use cheaper and safer materials. This rationale was reflected in a recently published paper by Nechaev et al., who explored the use of Vitamin B6 as redox-active molecules in aqueous electrolyte solutions.
The term Vitamin B6 actually refers to a set of six chemically related compounds called “vitamers”. Nechaev et al. reports that these B6 vitamers are soluble in water and likely very biodegradable, making them promising options for aqueous organic flow batteries, a subset of redox flow batteries that aim to use easily-accessible, water-based electroactive materials. The authors developed a synthetic strategy for producing several redox-active N-alkylated benzoyl pyridinium salts starting from pyridoxal hydrochloride, the oxidized form of vitamin B6. They then tested two of their salt products with a laboratory-scale flow battery using galvanostatic cycling, a method involving the application of a current to drive the redox reaction followed by the application of a reverse current to drive the reverse reaction. Nechaev et al. found that their compounds completely charged the battery but failed to discharge it. Using cyclic voltammetry as well as simulations that modeled electron transfer between the electrode and their redox-active pyridoxal derivative, they confirmed that their redox reaction involved a two-electron transfer process. They then analyzed this redox process with a computational study of the electrochemical reduction of one of their B6-based compounds, from which they concluded that the irreversibility observed in their battery test was likely due to an irreversible proton transfer step in the reduction process.
Although Nechaev et al. found negative results with their laboratory-scale flow battery testing, their study presented data which could be valuable for future studies of redox-active compounds and gave a promising demonstration of how creative chemical design may lead to the next generation of safer and more accessible RFB technology.
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References
(0) Nechaev, A. A., Gonzalez, G., Verma, P., Peshkov, V. A., Bannykh, A., Hashemi, A., Hannonen, J., Hamza, A., Pápai, I., Laasonen, K., Peljo, P., & Pihko, P. M. (2024). Exploration of vitamin B6-based redox-active pyridinium salts towards the application in aqueous organic flow batteries. Chemistry: A European Journal, e202400828. https://doi.org/10.1002/chem.202400828
(1) U.S. Energy Information Administration. (2020, February 21). Hourly electricity consumption varies throughout the day and across seasons. https://www.eia.gov/todayinenergy/detail.php?id=42915
(2) Ayodele, T. R., Jimoh, A., Munda, J. L., & Tehile, A. J. (2012). Challenges of grid integration of wind power on power system grid integrity: a review. International Journal of Renewable Energy Research, 2(4), 618-626.
(3) Yang, Z., Zhang, J., Kintner-Meyer, M. C. W., Lu, X., Choi, D., Lemmon, J., & Liu, J. (2011). Electrochemical energy storage for green grid. Chemical Reviews, 111(5), 3577-3613. https://doi.org/10.1021/cr100290v
(4) Weber, A. Z., Mench, M. M., Meyers, J. P., Ross, P. N., Gostick, J. T., & Liu, Q. (2011). Redox flow batteries: a review. Journal of Applied Electrochemistry, 41, 1137-1164. https://doi.org/10.1007/s10800-011-0348-2
Cover image by Red Zeppelin on Pexels.
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This is an unofficial adaptation of an article that appeared in a Chemistry Europe publication. Chemistry Europe has not endorsed the content of this adaptation or the context of its use.
