Argonne's Lithium-Ion Battery Technology Offers Reliability, Greater Safety

Researcher Michael Thackeray holds a model of the molecular structure associated with Argonne's advanced cathode material, a key element of the material licensed to NanoeXa.

Argonne's an internationally recognized leader in the development of lithium-battery technology. "Our success reflects a combined effort with a materials group and a technology group to exploit the concept to tackle key safety and energy problems associated with conventional technology," said Argonne's Michael Thackeray.

Recently, Argonne announced a licensing agreement with NanoeXa (see Transforum Vol. 7, No. 2, Summer 2007), a partnership that will introduce lithium-ion batteries with increased power output, storage capacity, safety, and lifetime. This partnership comes at a key time in the evolution of lithium-battery technology, especially as automakers eye these batteries as power sources for high-tech automotive applications. Successful application and public acceptance of the technology, however, depends on reliability, performance, and safety — the highest priority.

"What we're trying to do is to make the materials [used in lithium-ion batteries] safer for transportation applications," explained Thackeray. In fact, the safety issues associated with lithium-ion batteries grow as the cell size increases beyond what is currently used for consumer electronics — especially to the sizes needed for electric vehicle and hybrid electric vehicle applications.

To improve safety, Thackeray's colleagues in Argonne's Battery Technology Department are studying the thermal properties of lithium-ion cells and the mechanisms that control thermal runaway in conventional lithium-ion cell chemistries. Thermal runaway is a safety issue widely acknowledged and reported. To illustrate, in summer 2006, the media reported lithium-ion battery fires that were caused, at least in part, by thermal events. The result was massive battery recalls, forcing battery manufacturers to face significant financial losses.

Argonne has addressed that problem successfully by developing structurally integrated composite cathodes for lithium-ion batteries. "We have found," said Thackeray, "that our composite cathodes are less likely to cause thermal runaway compared to conventional layered lithium-metal-oxide electrodes such as LiCoO₂" Thackeray and his colleagues have developed stabilized lithium-manganese-nickel-oxide cathode materials that can tolerate high charging potentials. This approach cuts material costs by nearly half, extends life, and — importantly — improves safety.

"Our strategy is to use integrated materials to make electrode structures safer. In addition, we're improving safety by preconditioning the electrodes prior to use," explained Thackeray. "Also, colleagues of mine in our department have been successful in developing new electrolyte additives, which form more stable passivation films on the electrodes, thereby extending battery life and enhancing inherent safety."

In its continuing R&D efforts, Argonne is tailoring the composition of these structurally integrated "layered-layered" electrodes to achieve very high capacities. Argonne's strategy has proven highly successful. Said Thackeray, "We have demonstrated that our composite electrode structures have significant advantages over conventional lithium-ion battery electrodes in terms of their structural, electrochemical, and thermal properties."

These advantages translate into benefits to the lithium-ion battery industry and, ultimately, consumers who use products powered by these batteries. With further development, Argonne's battery technology can be used in applications in which rechargeable batteries with high energy and high power are needed while maintaining a high standard for safety. Ultimately, they could be used in transportation applications, where the need for power, long life, and reliability are essential.

As the science advances, the need to attract industry interest becomes more important. Increased visibility helps ensure that successful science done in the laboratory reaches those who can best put it to use. On February 23, 2007, Thackeray — by invitation from the White House — met with President Bush and participated in a round-table discussion on the role of lithium-ion batteries for transportation, including plug-in hybrid electric vehicles. Through this discussion, Thackeray had the opportunity to provide an overview on advanced batteries, address the challenges of advanced battery research and development, and talk about the path forward to achieving commercially viable lithium-ion battery-powered vehicles.

The future for Argonne's technology is promising. "Our technology is precisely what is needed to enable a timelier switch from a fossil-fuel economy to an economy that relies on alternative energy sources." Argonne's composite cathode invention offers the lithium-ion battery industry increased energy, power, and lifetime, with improved safety at a reduced cost. The attributes and advantages of Argonne's materials hold considerable promise for further improvements in the next generation of lithium-ion batteries.

January 25, 2008