Post-Test Analysis of Battery Materials:  Another Part of the Question

Thursday, May 15, 2014: 16:00
Bonnet Creek Ballroom I, Lobby Level (Hilton Orlando Bonnet Creek)
I. Bloom, N. D. Rago, A. N. Jansen, B. J. Polzin (Argonne National Laboratory), S. E. Trask (Chemical Sciences and Engineering Division, Argonne National Laboratory), and J. Bareno (Argonne National Laboratory)
Battery testing is an on-going program at Argonne.  Here, battery deliverables from DOE[1] and USABC[2]projects are evaluated in terms of initial performance and how that performance changes using standard sets of test protocols under a given set of conditions.  These test data provide a lot of information regarding how the battery performs and how performance changes.  The data are often used to infer what physical and/or chemical changes occurred in the battery, but they cannot definitively determine the exact cause of performance decline.  Post-test diagnostics can provide this missing information by using physical, spectroscopic, metallographic, and electrochemical tests.  Like battery testing, these methods are used in a standardized manner to make comparisons of failure modes within a given technology, and, perhaps, across technologies, easier.

As an example, small cells containing 5-V spinel cathodes and graphite anodes were cycled.  Upon disassembly, an unexpected “zebra” staining pattern was seen on the separator facing the anode and on the anode itself (see Fig. 1).  Further characterization of the separator by energy-dispersive spectroscopy (EDS) showed that lighter-colored areas had significantly more fluorine than did the dark-colored areas, as shown in Fig. 2.

This talk will describe Argonne’s Post-Test Facility, with an emphasis on capabilities and opportunities for collaboration. Cell disassembly, sample harvesting procedures and recent results will be discussed. In particular, SEM and XPS characterization of Li- and Mn-rich NMC and Li-Ni-Mn spinel cathodes, both pristine and aged in graphite-anode cells, reveal changes in chemical composition of evolved surface films.

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] US Department of Energy

[2] US Advanced Battery Consortium.  The USABC consists of representatives from the US DOE and from the three major automakers in the US, GM, Ford and Chyrsler.