Alvaro Masias1 2 Jeff Sakamoto2 3

1, Ford Motor Company, Dearborn, Michigan, United States
2, University of Michigan, Ann Arbor, Michigan, United States
3, University of Michigan, Ann Arbor, Michigan, United States

The recent resurgence of electrified vehicle product introductions seen in recent years has been enabled by meaningful advances in lithium ion batteries. This technology’s specific energy (Wh/kg) has improved steadily at nearly 8% per year. The achievement and maintenance of this specific energy growth rate has been the result of large, long term investment in improved battery research, development and manufacturing. However, to significantly promote the displacement of petroleum fuels from the transportation sector, a step increase in battery performance is necessary.

Solid state (SS) batteries are one of the most versatile and promising approaches of the various technologies under development for next generation energy storage. By enabling the use of high energy lithium metal anodes, SS batteries can enable major improvements in energy density. An approximately 50% gain in cell energy density is possible if SS electrolytes of comparable thickness to incumbent polyolefin separators could be developed to use metallic lithium anodes [1]. However, despite research efforts for more than 50 years, the mechanical properties of lithium metal are not well known.

A SS electrolyte material must fulfil various physical and chemical requirements to perform successfully in the battery environment. For example, some SS electrolytes have shown a tendency to allow for lithium dendrites to penetrate its structure once a critical charge density (CCD) has been reached [2]. Main of these requirements are driven by the need to conduct and contain lithium metal anodes and yet relatively little is known of the physical properties of this metal. A review of previous efforts to characterize the mechanical elastic constants, elastic and plastic deformation limits of metallic will be shown and compared to new bulk empirical results [3]. Additionally, the particular mechanical requirements of the battery environment will be discussed and future mechanical targets introduced.

[1] McCloskey, B. et al. J Phys. Chem. Lett. 6 (2015) 4581-4588.
[2] Sharafi, A. et al. J. Power Sources, 302 (2016) 135-139.
[3] Masias, A et al. ECS Fall Conf. (2017) Abs #205.