Battery performance and life testing is an ongoing program at Argonne National Laboratory. Batteries from U. S. Advanced Battery Consortium and U. S. Department of Energy projects are objectively evaluated according to well defined protocols [1]. Testing provides useful information about battery performance changes with time and, combined with statistical analysis and accelerated aging test conditions, allows forecasting performance over the expected lifetime of the devices [2]. This approach, however powerful, does not provide insight into the physicochemical causes of device degradation at the materials level. To address this issue, we have established a post-test analysis facility to elucidate physicochemical changes in Lithium-ion batteries responsible for performance degradation.Electrochemical performance is often limited by surface and interfacial reactions at the electrodes. However, routine handling of samples can alter the very surfaces that are the object of study. Our approach combines standardized testing of batteries with sample harvesting under controlled conditions. Cells of different formats are disassembled inside an argon-atmosphere glove box, with controlled water and oxygen concentrations below 1 ppm. Cell components are characterized under these conditions to guarantee that observed changes in physicochemical state are due to electrochemical operation, rather than sample manipulation.We employ a complementary set of spectroscopic, microscopic, electrochemical and metallographic methods to obtain a complete picture of cell degradation mechanisms. The resulting information about observed degradation mechanisms is provided to battery developers, both academic and industrial, to suggest new strategies and to accelerate the research and development cycle of Li-ion and related technologies.This work was performed under the auspices of the U.S. Department of Energy, Office of Vehicle Technologies, Hybrid and Electric Systems, under Contract No. DE-AC02-06CH11357.[1] USABC test manuals can be downloaded from http://www.uscar.org/guest/article_view.php?articles_id=86[2] �Statistical methodology for predicting the life of lithium-ion cells via accelerated degradation testing�. E. Thomas, I. Bloom, J. Christophersen, and V. Battaglia. J. Power Sources. 184  (2008) 312-317.

Argonne National Laboratory's post-test facility for analysis of lithium-ion battery materials

247th National Meeting (2014)

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