Researchers at the Department of Energy’s Pacific Northwest National Laboratory have performed a pioneering experiment that could alter the course of large-scale energy storage by increasing the capacity and lifespan of a flow battery by 60% using a starch-derived addition, -cyclodextrin.
In this grid energy resilience design, a sugar addition plays an unexpected function by increasing the capacity and lifespan of the flow batteries.
Pacific Northwest National Laboratory (PNNL) scientists have developed a new type of flow battery that uses a common food and pharmaceutical component called -cyclodextrin, which is generated from starch. After more than a year of continuous cycling, the flow battery retained its ability to store and release energy, according to a study published in the journal Joule.
In a world-first experiment, scientists were able to double the capacity and lifespan of a next-generation flow battery design by using a common food and medication additive.
The flow battery, developed by scientists at the Department of Energy’s Pacific Northwest National Laboratory, has been shown to retain its ability to store and release energy after being continuously charged and discharged for over a year.
Ruozhu Feng, a researcher in the field of flow batteries, poses with the components of a durable grid energy battery. Pacific Northwest National Laboratory; Andrea Starr
New research published in the journal Joule describes the first application of a simple sugar solution containing a derivative of starch called -cyclodextrin to increase battery life and energy storage. The scientists ran a battery of tests to find the optimal chemical mix that would yield the desired result of 60 percent increased peak power. Then they repeatedly cycled the battery for nearly a year, stopping only when the plastic tubing broke. Even after being dormant for so long, the flow battery retained almost all of its ability to store energy. More than a year of nonstop use with minimal capacity loss was reported, making this the first laboratory-scale flow battery experiment of its kind.
When added to a flow battery, -cyclodextrin speeds up the electrochemical reaction that stores and releases the energy in the battery through a process known as homogeneous catalysis. This means that the sugar is active while in solution, rather than when it is applied as a solid on a surface.
“This is a brand new approach to developing flow battery electrolyte,” said Wei Wang, the study’s senior investigator and a veteran PNNL battery expert. We proved that a novel kind of catalyst optimized for speeding up the energy conversion is viable. Furthermore, it is dissolved in the liquid electrolyte, so there is no solid to dislodge and foul the system.
Especially for grid reliability, flow batteries offer durable, rechargeable energy storage. Flow batteries, in contrast to solid-state batteries, store energy in a liquid electrolyte, represented here by the yellow and blue fluids. Using a pink sugar derivative called -cyclodextrin (purple) to speed up the chemical reaction that converts energy stored in chemical bonds (purple to orange), PNNL researchers developed a low-cost and efficient new flow battery. During charge and discharge, the positive and negative charges are balanced via a parallel reversible process (red-green) in the positive catholyte solution. Sara Levine, Pacific Northwest National Laboratory, is credited for her animation.
What is a flow battery?
Flow batteries, as their name implies, are made up of two separate containers filled with different liquids. Electrochemical reactions while charging store energy in the batteries. They store energy and then release it into an external circuit, which can be used to power electronics. Unlike traditional, solid-state batteries, flow batteries contain two external tanks of liquid supplying the electrolyte, which acts as the “blood supply” for the device. The capacity of a flow battery is proportional to the volume of its electrolyte supply tank.
Flow batteries, if built to the size of a football field or larger, might be used as emergency power for the electrical grid. To store energy from renewable energy sources, flow batteries are an integral part of any decarbonization strategy. One benefit is that they may be constructed on any scale, from the benchtop used in the PNNL study to a whole city block.
Why do we need new kinds of flow batteries?
The ability to store energy on a massive scale can be thought of as insurance against problems with the power infrastructure. Energy stored in large-scale flow battery facilities can assist prevent disruptions or restore service when severe weather or excessive demand hinder the ability to supply electricity to households and businesses. Since renewable energy sources like wind, solar, and hydroelectric power are becoming more commonplace, the demand for these flow battery facilities is only likely to rise. To meet customer demand, intermittent power sources like these need a place to store energy until it is needed.
Existing commercial facilities rely on mined minerals like as vanadium that are expensive and difficult to extract, despite the fact that there are various flow battery designs and some commercial installations. That’s why scientists are always on the lookout for safe and reliable alternatives to current technology that can be made from everyday items.
The electrolyte for a flow battery experiment that has showed promising results in the lab is being prepared. Pacific Northwest National Laboratory; Andrea Starr
An official from the Department of Energy’s Office of Electricity stated, “We cannot always dig the Earth for new materials,” which was a verbatim quote from Imre Gyuk, director of energy storage research. Just like the pharmaceutical and food sectors, we need to design a sustainable method using compounds that can be synthesized in big quantities.
The inauguration of PNNL’s Grid Storage Launchpad in 2024 will speed the lab’s extensive program to develop and test innovative technologies for grid-scale energy storage, including the work on flow batteries.
A benign ‘sugar water’ sweetens the pot for an effective flow battery
The new battery design was developed by a team of PNNL scientists with expertise in organic and chemical synthesis. These abilities proved useful when the team decided to use materials that had not previously been studied in battery research but were already manufactured for other industrial applications.
To paraphrase the lead author of the current work, “we were looking for a simple way to dissolve more fluorenol in our water-based electrolyte,” Ruozhu Feng. “The -cyclodextrin helped with that; it was only a little bit, but the real benefit was this unexpected catalytic ability.”
After that, they collaborated with Sharon Hammes-Schiffer of Yale University, a foremost expert on the chemical mechanism behind the catalytic boost, to write up their findings.
According to the study, the sugar component takes in protons, allowing the flow of electrons to remain balanced as the battery empties.