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Energy Storage R&D Showcased at Advanced Battery Conference

June 29, 2009

Researchers from NREL's Energy Storage Team presented results of several cutting-edge research projects at the premier Advanced Automotive Battery & EC Capacitor Conference held in mid-June in Long Beach, California. The first-of-its-kind conference provided a networking forum for attendees to learn about advances in battery and ultracapacitor research and development (R&D) and where the technology is heading. NREL's R&D in advanced batteries is sponsored by the U.S. Department of Energy's (DOE) Vehicle Technologies Office.

"Energy storage systems, such as batteries and ultracapacitors, are getting a lot of attention these days because of the role they play in making vehicles consume less petroleum through hybridization or electrification of transportation," said Ahmad Pesaran, principal engineer at NREL. "Energy storage systems are also expected to play a critical role in making the future electricity grid more energy efficient, and to enable market penetration of solar and wind electricity beyond 15%-20%. The conference provided us an opportunity to showcase research that can lead to new collaborations with industry."

Dr. Pesaran presented "Impact of the 3Cs of Batteries on PHEV Value Proposition: Cost, Calendar Life, and Cycle Life." His presentation demonstrated that, with careful consideration of battery depth of discharge, end-of-charge voltage design factors, and real-world usage (e.g., number of cycles per day and temperature exposure), cost, cycle life, and calendar life are all critical in making commercially viable plug-in hybrid electric vehicle (PHEV) batteries.

Another presentation, "Lithium-Ion Battery Safety Study Using Multi-Physics Internal Short-Circuit Model", given by Gi-Heon Kim, highlighted the results of linking and integrating NREL's electrochemical, electrothermal, and abuse reaction kinetics models to characterize an internal short and its evolution over time. The electrical, thermal, and electrochemical responses of a shorted cell change significantly for different types of internal shorts.

"Modeling of Nonuniform Degradation in Large-Format Li-ion Batteries" was presented by Kandler Smith. His presentation demonstrated that a one-dimensional lumped thermal model is inadequate, and specific regions of the battery change performance. His colleague Matt Keyser presented "Thermal Characterization of a Lithium-Ion Capacitor." This presentation offered important test results concluding that, under a 100-ampere discharge, the cell temperature increased only 7°C and no areas of thermal concern were identified during infrared cell testing.

Last but not least, Jeff Gonder presented "Fuel Economy and Performance of Mild Hybrids with Ultracapacitors". He showed that, through testing and modeling, the performance of a mild HEV with ultracapacitors is at least equal to or better than that of the Saturn Vue BAS HEV platform with its stock NiMH battery.

For more, see the Energy Storage Publications page.