Public Release: 

DOE names INEEL battery electrolyte best consumer product

DOE/Idaho National Laboratory

A team of chemists at the Department of Energy's Idaho National Engineering and Environmental Laboratory has been honored by the DOE for technology that demonstrates the DOE's commitment to save money and improve the quality of life for consumers.

The INEEL's lithium battery solid electrolyte topped a list of over 100 technologies nominated by the DOE laboratories nationwide for two special awards. Chemist Mason K. Harrup and colleagues received first place in both the Energy@23 and Bright Light categories.

Energy@23 Awards highlight innovations since the DOE was first established as a Cabinet agency in 1977, 23 years ago. Bright Light Awards honor developments within the last two years. The DOE assembled a team of citizen judges to choose among the technologies for those with the most consumer impact or future potential.

"I'm glad the DOE recognized the Idaho lab for the good work we do here," said electrolyte development team member Fred Stewart. "I'm exceedingly happy and surprised," said Harrup. "I realized we had a good technical program, but we're only in our fourth year. And the typical development horizon for these things is 10 years."

The team has submitted three patents and received one since 1998 on the electrolyte technology and is pursuing development collaborations with the space and satellite industry. According to Harrup, their initial target is for batteries to be used in space or heart pacemakers -- situations where a low-power battery needs to last a long time or work in very cold conditions.

The award-winning lithium battery solid electrolyte under development at the INEEL promises safer, more versatile and longer-lasting rechargeable batteries. Electrolytes are the key to creating a battery's electrical current by separating the positive and negative electrodes. Positive ions such as lithium can move through the electrolyte, but negatively charged electrons can't, so electrons travel out of the battery and through the device being powered, creating a current on their way. Conventional electrolytes are made of toxic salt solutions within a liquid or gel base, such as a car battery's water-based electrolyte.

Lithium batteries made with the experimental solid electrolyte last about 50% longer than competing electrolytes, offering substantial savings. The INEEL electrolyte is also safer and more environmentally friendly to produce than others. The waste products are essentially glass, phosphate and nitrogen compounds, which can be converted to fertilizer.

"Our biggest scientific breakthrough so far has been in understanding how the lithium ions move along the polymers," said Harrup. The team will be publishing several papers in the peer-reviewed scientific literature in the coming year.

The INEEL solid electrolyte is a mix of a liquid polymer and a ceramic powder that turns into a clear, non-toxic flexible membrane when properly blended. Other researchers have long studied similar polymers, known as polyphosphazenes, for use as a battery electrolyte. Much effort has gone into stiffening the liquid polymer.

The INEEL team developed a novel way to get the liquid polymer to hold shape without interfering with its ability to transport lithium ions. They discovered that the ceramic creates a stable scaffold and the liquid polymers weave through it like ribbons. Most importantly, this particular way of stabilizing the polymer interferes with lithium transport 20 times less than the most common stabilization method developed at other research institutions.

In addition, the researchers analyzed the electrolyte to determine how lithium ions traveled within the composite and if they would interact with the ceramic, a problem that could reduce ion movement. Using analytical chemistry methods, they determined that the lithium ions travel along the highly conductive polymer and virtually ignore the ceramic.

The electrolyte structure does have its drawbacks, Harrup explained. Since the polymers take ponderous routes through the ceramic scaffold, the traveling lithium ions take longer than they could. Also, the ions are limited to traveling single-file along the polymer paths, unlike in a liquid where ions simultaneously move across the electrolyte at once, like an army marching over a field. This limitation is optimal for low-power, slow-release applications such as pacemakers, but needs improvement for higher-power applications such as portable CD players. "This is not the next battery that's going in your Walkman," he said, pointing out years of development work are still needed.

"We're very pleased to receive this recognition," said Dave Miller, director of chemistry and geosciences at the INEEL. "We take this as an indication of the significance of the work we do at the lab."

Miller also pointed out that the composite owed some of its discovery to the multi-program nature of the INEEL. According to Miller, "The work comes from trying to understand the fundamental question of ion transport in harsh chemical environments. Some INEEL researchers were looking to use the polymers for environmental cleanup activities, and separately, some were developing batteries for the DOE's energy mission. People working on both were able to see the crossover."

Laboratory Director Bill Shipp was proud of the development group. "We're pleased that the DOE has recognized the value of the research at our lab. The expertise of INEEL membrane chemists goes back more than a decade. While most of their work addresses problems in environmental remediation, this is a great example of the broad applicability of membrane technology."

Other INEEL chemists who contributed to the solid electrolyte development are Joe Delmastro, who performed electrochemical testing; Alan Wertsching, who formulated the composite; Frederick F. Stewart, who developed the additives; Eric Peterson, who contributed expertise on polyphosphazene polymers; and Thomas A. Luther, who helped determine how the lithium ions are transported through the electrolyte.

The INEEL solid polymer electrolyte development program focuses on three elements: understanding how lithium ions move through the polymer, stabilizing the liquid polymer within a ceramic scaffold, and finding the best additives to improve performance of the electrolyte. The work was funded by the INEEL's Environmental Systems Research Candidates Program and the DOE's Office of Nonproliferation.

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The INEEL is a science-based, applied engineering national laboratory dedicated to supporting the U.S. Department of Energy's missions in national security, environment, energy and science. The INEEL is operated for the DOE by Bechtel BWXT Idaho, LLC, in partnership with the Inland Northwest Research Alliance.

Deborah Hill, 208-526-4723, dahill@inel.gov

Visit out website at http://www.inel.gov

Note to editors: A full listing of DOE Energy@23 and Bright Light awards can be found at the URL http://www.ma.doe.gov/energy100/. Photos of the electrolyte are available from the media contact below. Mason K. Harrup can be reached at 208-526-1356 or harrmk@inel.gov.

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