Abstract
We report a method for promoting electrochemical stability in garnet Li6.4La3Zr1.4Ta0.6O12 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 Li6.4La3Zr1.4Ta0.6O12 lattice. Density functional theory (DFT) calculations identify a thermodynamically favourable reaction path and show how substituting Ta5+ at Zr4+ 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 Li6.4La3Zr1.4Ta0.6O12 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.
| Original language | English |
|---|---|
| Journal | Nature Materials |
| DOIs | |
| State | Accepted/In press - 2025 |
Funding
Y.W., H.F., P.J., M.F. and Y.Q. were supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the US Department of Energy (DOE) through the Advanced Battery Materials Research Program (Battery500 Consortium, contract number 674882). V.R., K.G.N., B.S.V., P.P.M. and D.M. were supported by the Mechano-Chemical Understanding of Solid Ion Conductors, an Energy Frontier Research Center funded by the US DOE, Office of Science, Office of Basic Energy Science, contract number DE-SC0023438. S.K.’s research at Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the US DOE under contract number DE-AC05-00OR22725, was supported by the US DOE’s Office of Energy Efficiency and Renewable Energy for the Vehicle Technologies Office’s Advanced Battery Materials Research Program. H.F. acknowledges the Office of Advanced Research Computing (OARC) at Rutgers, The State University of New Jersey for providing access to the Amarel cluster and associated research computing resources that have contributed to the results reported here. H.F. and P.J. acknowledge resources from the National Renewable Energy Laboratory High-Performance Computing Facilities (with Kestrel and Swift computing systems). The acquisition of the VersaProbe-IV XPS was supported by the National Science Foundation Major Research Instrumentation program (grant number 2117623). This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated by the US DOE’s Office of Science. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is managed by Triad National Security, LLC, for the US DOE’s National Nuclear Security Administration (NNSA), under contract number 89233218CNA000001. This research used the hard X-ray nanoprobe beamline at 3-ID of the National Synchrotron Light Source II, US DOE, Office of Science User Facility, operated for the DOE’s Office of Science by Brookhaven National Laboratory under contract number DESC0012704. This work was supported by The Welch Foundation (F-2206). Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC (NTESS), a wholly owned subsidiary of Honeywell International Inc., for DOE/NNSA under contract number DE-NA0003525. This written work is authored by an employee of NTESS. The employee, not NTESS, owns the right, title and interest in and to the written work and is responsible for its contents. Any subjective views or opinions that might be expressed in the written work do not necessarily represent the views of the US government. The publisher acknowledges that the US government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this written work or allow others to do so, for US government purposes. The DOE will provide public access to results of federally sponsored research in accordance with the DOE Public Access Plan.