Iowa State University researchers work to build new batteries for energy storage

As new technologies consume more power and alternative energy sources become increasingly necessary to fuel Iowans’ lives, Iowa State University researchers are working to create new batteries from accessible materials to store power from variable sources.

Steve Martin and Patrick Johnson, both materials science and engineering professors at ISU, have earned a nearly $459,000 grant from the Iowa Energy Center to develop batteries using sodium, waste glass, biochar and sulfur — materials they’ve already tested and found viable.

Building on a previous grant from the center, the researchers hope to create batteries that are both safer and cheaper than their lithium-ion peers.

“We’re always evolving our research, and of course, materials are evolving with us,” Martin said. “We’re also evolving, at the same time, what you might consider the assembly of the battery as well.”

Martin, who has 40 years of experience researching batteries, said there’s been a recent push to develop more battery production in the U.S. In 2019, he and a team earned a grant from the Iowa Energy Center to work on a “sodium stationary battery,” with his focus on the separator between the anode and cathode of the battery.

The initial project led Martin to develop a “glassy, solid electrolyte as a separator” that is highly conductive and easily processable, leading him to team up with Johnson for what he called the “second phase” to create working batteries.

Most of the materials the team is using to make these batteries are accessible in Iowa — sodium to replace lithium, waste glass for the separator, and biochar for the anode. Sulfur, which will be used for the cathode, can’t be purchased from anywhere in Iowa, Martin said, but the petroleum industry byproduct is low-cost and easy to acquire.

Building batteries, filling reservoirs of energy

Sodium ions move between the anode and cathode of the battery, Martin said, like water in a reservoir. “Just like water flowing through a dam generates power,” he said the sodium ions will flow across the “high voltage, or high elevation” anode to create the same effect. Martin’s group will create a sodium sulfide product in order to “fill the reservoir.”

These batteries will be built backward compared to the construction of a reservoir, however, where water fills the reservoir first and then discharges. Martin said they’re building the reservoir — “the low voltage part” — on the bottom, then charging the sodium back to the reservoir at the top when the battery is connected and charging.

“If you build the battery with sodium in the cathode … you might say it’s already reacted, it’s lost its potential energy, like the analogy of the reservoir, and so it doesn’t have any reactivity, as much,” Martin said. “And so then you can build the battery, seal it all up, protect it from everything, and then you can charge the sodium back up the hill, you might say.”

Johnson provided another analogy for his part in this work, comparing the graphite used in other batteries with the hard carbon he is focusing on for the new technology. He said to think about graphite as a tightly stacked pile of papers, with gaps big enough for lithium to pass through but not sodium.

The gaps in hard carbon are large enough for sodium to get inside, Johnson said, like when a stack of papers is dropped then shuffled back together.

“Our group is working on the separator … and the cathode, and Professor Johnson’s group is working on the anode — how to create that reservoir, you might say, to catch as much sodium as possible, and how to release that sodium as fast as possible, so that the battery operates very well,” Martin said.

Helping Iowa’s wind energy economy

While the new batteries will operate similarly to lithium-ion batteries, Martin said their voltage will be lower, requiring more batteries stacked together to reach the lithium voltage. Johnson added these batteries will be pouch cells, which are used commercially.

When it’s time to actually put together the battery’s parts and test it, they’ll be able to do so at a battery fabrication and testing center now up and running at ISU. Once the team has reached the point where they have assembled batteries with performance data gathered, Martin said they will explore the potentials of launching their own startup company or licensing the technology to another battery company.

Martin said the biggest impact he expects to see from this work is to “provide energy storage systems to help level out the supply-demand curves for wind turbines here in Iowa,” allowing the storage of energy when winds are high but need isn’t rising to match it. That way, whenever energy is needed but the wind isn’t blowing, saved power is still available.

Johnson said there is also the safety benefit to consider, as other batteries have fire risks and “solid-state batteries” have a much lower risk.

Wind energy, and the additional energy storage these batteries could provide, will become increasingly more important in the future as technology like data centers powering artificial intelligence spread across the U.S. and in Iowa.

“This stable energy source allows more stability in the network, in the grid, and I think it makes the overall electric portfolio in our state more robust,” Martin said.

As engineers, Martin said this work and the changes it could bring is “really what it’s all about” — asking questions of how to move society forward and make Iowans’ lifestyles more sustainable, productive, fruitful and enjoyable and finding the answers.

However, both Martin and Johnson said their number one priority is training and teaching students. Martin said “if you’re not developing and standing still, you’re losing,” and in order for Iowa to advance and remain on the cutting edge, advanced education and research need to stay at the forefront of university operations.

“It’s always fulfilling to see our former students out in the workforce and doing great things,” Johnson said. “So that opportunity to be able to work on these cutting edge projects brings in curious and enthusiastic students, and then they go out and continue working in these areas, and bring that knowledge and experience they have.”