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Steve Martin has been working for decades to find better materials for safer, more powerful batteries. By using certain sulfide glasses, he’s been able to demonstrate that glassy solids can be a low-cost, high-performance, safe, and stable electrolyte for lithium-ion batteries. (Christopher Gannon)

Glassy breakthrough for battery performance

Steve Martin, an Anson Marston Distinguished Professor in Engineering at Iowa State University and an associate of the U.S. Department of Energy's Ames Laboratory, has researched battery materials for nearly 40 years. Specifically, he has been studying and measuring the basic properties of glassy solids: How do ions move through them, how mechanically robust are they, and how is their thermal and chemical stability?

Martin has long thought that using glassy solids as the electrolytes in batteries would make for safer, more powerful batteries. But there was limited research funding for battery studies and most of that was directed toward liquid-electrolyte batteries that have had problems with fires and energy capacity.

So as he tells it, he worked hard for any support that allowed him to study fundamental properties of materials with potential for improving battery performance. That work was all about laying a foundation that would enable Martin and his research group to develop new, "all-solid-state" batteries whenever research funding was available.

Fast forward to today, when as it so happens, millions, if not billions, of people around the world rely on battery-powered phones, not to mention transportation systems. Asian countries currently dominate the entire battery industry, and as such much of the U.S. government's research agenda has started to allocate for research and development of battery technology toward the goal of a domestic battery industry.

Martin and his team, in fact, has been awarded a three-year, $2.5 million grant from the DOE’s Advanced Research Projects Agency–Energy and its new Integration and Optimization of Novel Ion-Conducting Solids (IONICS) program. There’s additional, cost-share funding from Iowa State and the Iowa Energy Center.

“This is my dream-come-true project,” Martin said. “This is what I’ve been working on for 36 years.”

[Note: In September 2016, ARPA-E announced it had awarded $37 million in funding for 16 new projects as part of its IONICS program, which is focused on technologies that have promise in overcoming the limitations of current battery and fuel-cell products. Details on all 16 of the IONICS projects can be found by clicking here.]

Since his undergraduate days, which he says coincided with the energy crisis of the 1970s, Martin has thought there must be a better way to power the country than fossil fuels and internal combustion. But alternatives such as electric vehicles came with many limitations, including battery cost and performance.

When he began his doctoral studies in 1980 at Purdue University, Martin began looking for new materials that could improve battery performance. He eventually settled on using glass as a solid electrolyte in batteries.

Battery electrolytes allow ions—atoms that have lost or gained electrons and are therefore positively or negatively charged—to flow back and forth between a battery’s electron-accepting cathode and electron-losing anode. The resulting electrochemical reactions produce electricity.

Commonly used organic liquid electrolytes in lithium-ion batteries are a problem, Martin said. They’re as chemically reactive as gasoline and so they can—and do—catch on fire. Batteries based on them can also leak the flammable liquid. To make them safer, manufacturers slash the energy levels of the batteries.

“It works,” Martin said. “But it operates at a fraction of its theoretical maximum energy density.”

Martin thought using a stable, solid electrolyte would be a better, safer way to build batteries. But it can be a challenge to move ions through solids, one of the reasons it has taken decades for Martin and his research group to understand the movement of ions through glass.

By using certain sulfide glasses, he’s been able to accelerate that movement, or conductivity. The new grant will allow Martin to demonstrate that glassy solids can be a low-cost, high-performance, safe, and stable electrolyte for lithium-ion batteries.

“And so maybe you’re recharging your device every week instead of daily,” Martin said. “Or maybe an electric vehicle that can now go 40 miles on a charge will be able to go 200 miles.”

The grant will help Martin purchase equipment to scale up his lab’s glass production. If the production and studies go well, Martin said the grant encourages technology transfer to a spin-off company or to industry.

“Our goal is not just to make safer batteries, but also to increase energy capacity. We think we can increase capacity by a factor of 10,” he said.

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