DOE OSTI · 3015585
Grain boundary zirconia-modified garnet solid-state electrolyte
Abstract
Here, we report a method for promoting electrochemical stability in garnet Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 solid-state electrolyte based on a composite two-phase oxide–oxide microstructure. Grain boundary precipitation of the controlled distribution of amorphous zirconium oxide microparticles is achieved through the addition of reactive tantalum carbide. During ambient-atmosphere sintering, the carbide decomposes through an in situ reaction, the ‘extra’ Ta substituting for Zr within the Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 lattice. Density functional theory (DFT) calculations identify a thermodynamically favourable reaction path and show how substituting Ta 5+ at Zr 4+ sites affects the crystal structure as well as bulk ionic and electronic conductivities. Quantitative stereology highlights that zirconia also acts as a sintering aid, reducing compact porosity. Cryogenic focused-ion-beam scanning electron microscopy and fractography analysis of cycled solid-state electrolytes illustrates that near-universally observed intergranular Li-metal dendrite propagation is suppressed by the two-phase microstructure, favouring transgranular dendrites instead. Importantly, DFT demonstrates that compared with the Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 surface, the zirconium oxide surface per se is less electronically conductive and does not trap excess electrons to reduce Li ions. This is a key reason for the substantial improvement in the electrochemical properties over the single-phase baseline.
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Raj, Vikalp [Univ. of Texas, Austin, TX (United States)] (ORCID:0000000158735446), Wang, Yixian [Univ. of Texas, Austin, TX (United States)] (ORCID:0000000161078352), Feng, Min [Brown Univ., Providence, RI (United States)], Naik, Kaustubh G. [Purdue Univ., West Lafayette, IN (United States)], Jain, Manish [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0000000318831382), Vishnugopi, Bairav S. [Purdue Univ., West Lafayette, IN (United States)] (ORCID:0009000263579358), Deng, Shimao [Univ. of Texas, Austin, TX (United States)], Schorr, Noah B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0000000215828594), Salazar, Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)], Heusser, Alexander M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)], Huang, Xiaojing [Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)] (ORCID:0000000160345893), Manning, Andrew Scott [Univ. of Texas, Austin, TX (United States)], Kalnaus, Sergiy [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000274653034), Liu, Yijin [Univ. of Texas, Austin, TX (United States)] (ORCID:0000000284172488), Watt, John [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)] (ORCID:0000000280129837), McBrayer, Josefine D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0000000222525786), Boyce, Brad L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0000000159941743), Fang, Hong [Rutgers University, Camden, NJ (United States)] (ORCID:0000000209688687), Jena, Puru [Virginia Commonwealth Univ., Richmond, VA (United States)] (ORCID:000000022316859X), Mukherjee, Partha P. [Purdue Univ., West Lafayette, IN (United States)], Qi, Yue [Brown Univ., Providence, RI (United States)] (ORCID:0000000153311193), Mitlin, David [Univ. of Texas, Austin, TX (United States)]. 2025-10-15. Grain boundary zirconia-modified garnet solid-state electrolyte. https://doi.org/10.1038/s41563-025-02374-9
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