Sugar additive plays a surprise role, boosting flow battery capacity and longevity for this grid energy resilience design.
A team of researchers from the Department of Energy’s Pacific Northwest National Laboratory (PNNL) has made a significant breakthrough in flow battery design using a common food and medicine additive called β-cyclodextrin, derived from starch. The study, published in the journal Joule, reveals that the flow battery maintained its capacity for energy storage and release for over a year of constant cycling.
A common food and medicine additive has shown it can boost the capacity and longevity of a next-generation flow battery design in a record-setting experiment.
A research team from the Department of Energy’s Pacific Northwest National Laboratory reports that the flow battery, a design optimized for electrical grid energy storage, maintained its capacity to store and release energy for more than a year of continuous charge and discharge.
The study, just published in the journal Joule, details the first use of a dissolved simple sugar called β-cyclodextrin, a derivative of starch, to boost battery longevity and capacity. In a series of experiments, the scientists optimized the ratio of chemicals in the system until it achieved 60 percent more peak power. Then they cycled the battery over and over for more than a year, only stopping the experiment when the plastic tubing failed. During all that time, the flow battery barely lost any of its activity to recharge. This is the first laboratory-scale flow battery experiment to report more than a year of continuous use with minimal loss of capacity.
The β-cyclodextrin additive is also the first to speed the electrochemical reaction that stores and then releases the flow battery energy, in a process called homogeneous catalysis. This means the sugar does its work while dissolved in solution, rather than as a solid applied to a surface.
“This is a brand new approach to developing flow battery electrolyte,” said Wei Wang, a long-time PNNL battery researcher and the principal investigator of the study. “We showed that you can use a totally different type of catalyst designed to accelerate the energy conversion. And further, because it is dissolved in the liquid electrolyte it eliminates the possibility of a solid dislodging and fouling the system.”
What is a flow battery?
As their name suggests, flow batteries consist of two chambers, each filled with a different liquid. The batteries charge through an electrochemical reaction and store energy in chemical bonds. When connected to an external circuit, they release that energy, which can power electrical devices. Flow batteries differ from solid-state batteries in that they have two external supply tanks of liquid constantly circulating through them to supply the electrolyte, which is like the “blood supply” for the system. The larger the electrolyte supply tank, the more energy the flow battery can store.
