Abstract
Despite the broad interest in Al-doped lithium lanthanum zirconium oxide (LLZO), the wide range of reported ionic conductivities suggests that the effect of processing parameters on the resulting phase purity and bulk conductivity is not well-understood. Here, we synthesized six separate series of LLZO with variations in Al concentration, Li excess, Li addition order, Li source, densification method, and mother powder to determine the effect on the composition, phase purity, density, and bulk conductivity. We found that a wider range of compositions (6.08-7.61 mol of Li and 0.06-0.23 mol of Al) than previously reported can result in cubic phase stability and that nearly all elements (Li, Al, Zr, and La) are lost to the MgO crucible during calcination and sintering. The manner in which different elements are lost is affected by the processing parameters. We observed that Al-doped LLZO shows great compositional flexibility in stabilizing the cubic phase, offering an explanation for the range of electrochemical performance metrics reported in the literature.
| Original language | English |
|---|---|
| Pages (from-to) | 3003-3019 |
| Number of pages | 17 |
| Journal | ACS Applied Energy Materials |
| Volume | 8 |
| Issue number | 5 |
| DOIs | |
| State | Published - Mar 10 2025 |
Funding
A.C.M. would like to thank Jeffrey Einkauf and Diana Stamberga in Oak Ridge National Laboratory’s Chemical Separations Group for repeated access to the ICP used in this work. This material is based on work supported by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education for the DOE under contract number DE-SC0014664. A.C.M. would like to thank the Rackham Graduate School at the University of Michigan for support through the Rackham Pre-Doctoral Fellowship. A portion of this work (materials synthesis, ICP, EIS, XRD, and data analysis) was performed at the Oak Ridge National Laboratory (G.M.V., R.L.S., A.L.M., and A.C.M.) and supported by the U.S. Department of Energy’s Vehicle Technologies Office under the US-Germany Consortium Project, directed by Tien Duong. This manuscript has been authored in part by UT-Battelle, LLC, under contract DEAC05-00OR22725 with the U.S. Department of Energy (DOE). The publisher, by accepting the article for publication, acknowledges that the U.S. 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 U.S. government purposes. The DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doepublic-accessplan).
Keywords
- Al loss
- Li loss
- conductivity
- crucible
- lithium lanthanum zirconium oxide
- synthesis