High-Energy Li-Ion Batteries: Full Cell and Electrode Monitoring for Evaluating Cycling and Impedance Performance of Layered Oxide//Si-Graphite Cells
We have previously used reference electrode measurements for the successful distinction and evaluation of positive and negative electrode contributions to the full cell impedance in aging studies [4, 5]. In the present work, full cell cycling and impedance behavior of a silicon-graphite and layered oxide system is explored in detail by simultaneous monitoring of the positive and negative electrodes. The negative electrode is a mixed silicon-graphite electrode (15 wt% Si, NanoAmor, 73 wt% graphite, Hitachi MAGE, 2wt% carbon, C45 Timcal), and the positive electrode has 90 wt% Li1.03 (Ni0.5Co0.2Mn0.3)0.97O2 (Toda NCM523). Both were obtained from the Cell Analysis, Modeling, and Prototyping (CAMP) Facility, Argonne National Laboratory. A new cell set-up is used that combines both a Li metal reference electrode to examine cycling behavior and a Li~4.4Sn micro-reference electrode for impedance measurements at different SOC, in order to account for electrode utilization and impedance in relation to cell performance.
The effect of various system variables on performance and aging are explored and will be discussed in the presentation, including the effect of cut-off potentials and electrolyte compositions. Our results provide insight into the performance and characteristics of electrode materials that are being considered for high energy and high voltage cells, and contribute to the development of strategies for their utilization when combined.
Acknowledgements: Financial support from the Gålö Foundation, the Swedish Royal Academy of Engineering Sciences (IVA), and the U.S. Department of Energy’s Office of Vehicle Technologies is gratefully acknowledged.
 W.J. Zhang, J. Power Sources, 196 (2011) 13-24.  M.N. Obrovac, L. Christensen, Electrochem. Solid -State Lett., 7 (2004) A93-A96.  Y. Li, M. Bettge, B. Polzin, Y. Zhu, M. Balasubramanian, D.P. Abraham, J. Electrochem. Soc., 160 (2013) A3006-A3019.  D.P. Abraham, S.D. Poppen, A.N. Jansen, J. Liu, D.W. Dees, Electrochim. Acta, 49 (2004) 4763-4775.  M. Klett, T.G. Zavalis, M.H. Kjell, R.W. Lindstrom, M. Behm, G. Lindbergh, Electrochim. Acta, 141 (2014) 173-181.