Critical current density of Li6PS5Cl powder pellets and processed films

Description

All-solid-state batteries are regarded as one of the more promising technologies to improve safety and performance of current energy storage solutions. Especially the envisioned use of a metallic lithium anode could increase the energy density significantly. Li dendrite formation and the corresponding risk of internally shorting the battery cell is expected to be fully inhibited by using a thin, solid electrolyte sheet with high shear modulus [1].
Sulfide-electrolytes, especially the argyrodite family (Li6PS5X, X = Cl, Br) have attracted much attention for use in all-solid-state lithium batteries due to their high ionic conductivity (> 1 mS cm-1, RT) and feasible processability [2]. Although they also offer high mechanical stability [3], lithium dendrite growth remains an issue for cells employing this material. Especially, thin sheets prepared by combination of the electrolyte powder with a suitable binder suffer from a decrease in the electrochemical and mechanical performance.
Thus, the practicality of sulfide-electrolytes for use in battery cells with relevant power output is still a matter of debate. One key parameter to evaluate this materials class in more detail is the critical current density, i.e. the maximum current that can be applied to a battery cell without excessive Li dendrite formation. It is frequently determined in literature, however, due to the non-standard evaluation, the obtained data often lacks comparability and meaning (e.g. too low areal capacities are used, limiting conditions are not clarified). Many parameters which have a significant impact on the obtained critical current density are not controlled or reported [4].
Therefore, we conducted a series of systematic investigations on the critical current density of pressed Li6PS5Cl powder pellets as well as processes films. First, the influences of the measurement procedure (step vs. continuous), cell setup (casing, Li source), and sample geometry (thickness, diameter) on the obtained critical current densities were determined. Then, powder pellets and films were tested using a set of optimized parameters. Thus, the practicality and limits of the Li6PS5Cl solid-electrolyte for use in battery cells has been evaluated.

References
[1] X. Ke, Y. Wang, G. Ren, Energy Storage Materials, 26, 313-324 (2020)
[2] C. Yu, F. Zhao, J. Luo, L. Zhang, X. Sun, Nano Energy, 83, 105858 (2021)
[3] D.K. Singh, A. Henss, B. Mogwitz, A. Gautam, J. Horn, T. Krauskopf, S. Burkhardt, J. Sann, F.H. Richter, J. Janek, Cell Reports Physical Science, 3, 101043 (2022)
[4] Y. Lu, C-Z. Zhao, H. Yuan, X-B. Cheng, J-Q. Huang, Q. Zhang, Adv. Funct. Mater., 31, 2009925 (2021)

Acknowledgments
This project has received funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 875028 (SUBLIME Project).

Period	9 Jul 2023
Event title	The 18th European Conference on Solid State Chemistry (ECSSC 2023)
Event type	Conference
Location	Prague, Czech RepublicShow on map
Degree of Recognition	International