According to researchers from Harvard John A. Paulson School of Engineering and Applied Sciences/SEAS, it is now possible to make flow batteries more practical.
It is worth noting that flow batteries can store energy in liquid-filled tanks, but the only problem that was being experienced previously was that after a few charge-discharge cycles the batteries started suffering from rapid degradation of their storage capacity.
This hurdle was addressed by the researchers in their latest experiment.
The results of their experiment were quite promising and the team disclosed it in a press release.
The researchers managed to modify the molecular structure in the flow batteries’ solution to enhance their water solubility.
This enabled the electrolytes to get dissolved quickly in neutral water and generated a battery that lost just 1% of its storage capacity with the passage of every 1000 cycles.
Now the battery could run for at least ten years with minimum upkeep requirements.
It was also revealed that the solution is different from other battery liquids as it is not just non-toxic but non-corrosive as well.
That is, even if it touches skin or is spilled onto the floor, no damage will be incurred.
This indeed is a breath of fresh air in a world where identifying new ways to switch to renewable energy and make it sustainable has become the foremost target of every research-based institution.
The innovation in energy storage would help renewable energy become a valuable and viable source of power.
As stated by Imre Gyuk from the US Department of Energy that “efficient, long duration flow batteries will become standard as part of the infrastructure of the electric grid,” since these can store energy for lower than $100 per kWh and thus, would most likely generate energy from sources like wind and sun.
This would be a great option considering that it will lessen the demand on a grid station during peak usage durations.
Many such innovations are the need of the day so that the use of fossil fuels could be undermined and dependence upon environmentally harmful power generation sources could be decreased on the whole.
This would be a great option considering that it will lessen the demand on a grid station during peak usage durations.
Many such innovations are the need of the day so that the use of fossil fuels could be undermined and dependence upon environmentally harmful power generation sources could be decreased on the whole.
The research, published in ACS Energy Letters, was led by Michael Aziz, the Gene and Tracy Sykes Professor of Materials and Energy Technologies and Roy Gordon, the Thomas Dudley Cabot Professor of Chemistry and Professor of Materials Science.
“Lithium ion batteries don’t even survive 1000 complete charge/discharge cycles,” said Aziz.
“Because we were able to dissolve the electrolytes in neutral water, this is a long-lasting battery that you could put in your basement,” said Gordon.
“If it spilled on the floor, it wouldn’t eat the concrete and since the medium is noncorrosive, you can use cheaper materials to build the components of the batteries, like the tanks and pumps.”
This reduction of cost is important.
The Department of Energy (DOE) has set a goal of building a battery that can store energy for less than $100 per kilowatt-hour, which would make stored wind and solar energy competitive to energy produced from traditional power plants.
“If you can get anywhere near this cost target then you change the world,” said Aziz. “It becomes cost effective to put batteries in so many places. This research puts us one step closer to reaching that target.”
“This work on aqueous soluble organic electrolytes is of high significance in pointing the way towards future batteries with vastly improved cycle life and considerably lower cost,” said Imre Gyuk, Director of Energy Storage Research at the Office of Electricity of the DOE. “I expect that efficient, long duration flow batteries will become standard as part of the infrastructure of the electric grid.”
The key to designing the battery was to first figure out why previous molecules were degrading so quickly in neutral solutions, said Eugene Beh, a postdoctoral fellow and first author of the paper.
By first identifying how the molecule viologen in the negative electrolyte was decomposing, Beh was able to modify its molecular structure to make it more resilient.
Next, the team turned to ferrocene, a molecule well known for its electrochemical properties, for the positive electrolyte.
“Ferrocene is great for storing charge but is completely insoluble in water,” said Beh. “It has been used in other batteries with organic solvents, which are flammable and expensive.”
But by functionalizing ferrocene molecules in the same way as with the viologen, the team was able to turn an insoluble molecule into a highly soluble one that could also be cycled stably.
“Aqueous soluble ferrocenes represent a whole new class of molecules for flow batteries,” said Aziz.
The neutral pH should be especially helpful in lowering the cost of the ion-selective membrane that separates the two sides of the battery. Most flow batteries today use expensive polymers that can withstand the aggressive chemistry inside the battery. They can account for up to one third of the total cost of the device. With essentially salt water on both sides of the membrane, expensive polymers can be replaced by cheap hydrocarbons.
This research was coauthored by Diana De Porcellinis, Rebecca Gracia, and Kay Xia. It was supported by the Office of Electricity Delivery and Energy Reliability of the DOE and by the DOE’s Advanced Research Projects Agency-Energy.
With assistance from Harvard’s Office of Technology Development (OTD), the researchers are working with several companies to scale up the technology for industrial applications and to optimize the interactions between the membrane and the electrolyte. Harvard OTD has filed a portfolio of pending patents on innovations in flow battery technology.
