Silver Doped Lithium Metal Thin Films for Solid-State Batteries

Potential use of lithium metal anode is a primary factor behind the high-energy density promise of solid-state batteries. However, large anodic loads lead to void formation and contact loss at the lithium/solid electrolyte interface which, in turn, lead to much higher effective local current densities during the subsequent lithium plating, causing dendrite formation and cell shorting.1, 2 This is due to the slow self-diffusion of Li atoms/vacancies, which is an inherent limitation of lithium metal.3 Modifying the bulk physiochemical properties of lithium metal via doping/alloying (<10 at% dopant) is an attractive approach, as such a small concentration of dopants can alter lithium metal’s bulk properties, without lowering its energy density. As an example, pore formation was effectively eliminated by alloying Li with 10 at% Mg, although chemical diffusion of Li within the alloy still restricted its rate performance.4 In this work, we report the effects of Ag as a dopant on the morphological stability and rate capability of Li-Ag alloy anodes during electrochemical cycling, as its concentration is varied in Li from 0-10 at.%. The alloy samples are prepared as 10 μm thick films, a practical form factor for solid-state batteries, via a combination of sputtering and thermal evaporation. Comparison of performance as a function of Ag content will be presented for both polymeric and inorganic solid-state electrolytes. Structural characterization of the alloy anodes via complementary techniques will also be presented. This research was sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory (ORNL). This abstract has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). References Kasemchainan, J.; Zekoll, S.; Spencer Jolly, D.; Ning, Z.; Hartley, G. O.; Marrow, J.; Bruce, P. G., Critical stripping current leads to dendrite formation on plating in lithium anode solid electrolyte cells. Nature Materials 2019, 18 (10), 1105-1111. Krauskopf, T.; Hartmann, H.; Zeier, W. G.; Janek, J., Toward a Fundamental Understanding of the Lithium Metal Anode in Solid-State Batteries—An Electrochemo-Mechanical Study on the Garnet-Type Solid Electrolyte Li6.25Al0.25La3Zr2O12. ACS Applied Materials & Interfaces 2019, 11 (15), 14463-14477. Jow, T. R.; Liang, C. C., Interface Between Solid Electrode and Solid Electrolyte—A Study of the Li / LiI ( Al2 O 3 ) Solid‐Electrolyte System. Journal of The Electrochemical Society 1983, 130 (4), 737-740. Krauskopf, T.; Mogwitz, B.; Rosenbach, C.; Zeier, W. G.; Janek, J., Diffusion Limitation of Lithium Metal and Li–Mg Alloy Anodes on LLZO Type Solid Electrolytes as a Function of Temperature and Pressure. Advanced Energy Materials 2019, 9 (44), 1902568.