Generally in-situ studies of batteries employ a custom-made research cell that is designed with “windows” in the casing that are x-ray transparent. Such cells typically employ a simple coin-cell-type design where two discs of electrode material are pressed together in an air-tight assembly[2, 3]. While these types of cells are very useful and convenient for most materials research, they cannot exactly replicate the conditions present in many common commercial cells, and they are not generally suitable for long-term studies on ageing and degradation.
The work presented here demonstrates several examples of how synchrotron techniques can be used to analyze unmodified commercial pouch cells. With high brilliance and tunability of incident wavelength, synchrotron light can be used to penetrate commercial cell casings and analyze active electrode material in-operando. At the Canadian Light Source, SR-XRD was used to analyze the crystal structure and phase changes in an operating commercial nickel-manganese-cobalt-oxide/graphite pouch cell. Transmission SR-XRD was also used to map structural inhomogeneities in cell components with high spatial resolution. In-operando XAS was also successfully carried out on an unmodified commercial pouch cell, which will provide a simple means of monitoring changes in structure and redox chemistry as commercial batteries undergo long-term ageing, cycling, and stress testing.
[1] Yoon W-S, Grey CP, Balasubramanian M, Yang X-Q, Fischer DA, McBreen J. Electrochem Solid-State Lett., 2014, 13, 1051-1061.
[2] De Marco R, Veder JP. Trends in Analytical Chem., 2010, 29, 6.
[3] Herklotz M, Scheiba F, Hinterstein M, Nikolowski K, Knapp M, Dippel AC, Giebeler L, Eckert J, Ehrenberg H. J. Appl. Cryst., 2013, 46, 1117-1127.