Enhanced Performance of Li6.4La3Zr1.4Ta0.6O12 Solid Electrolyte by the Regulation of Grain and Grain Boundary Phases

Zeya Huang; Linhui Chen; Bing Huang; Biyi Xu; Gang Shao; Hailong Wang; Yutao Li; Chang-An Wang

doi:10.1021/acsami.0c18674

Enhanced Performance of Li_6.4La₃Zr_1.4Ta_0.6O₁₂ Solid Electrolyte by the Regulation of Grain and Grain Boundary Phases

ACS Appl Mater Interfaces. 2020 Dec 16;12(50):56118-56125. doi: 10.1021/acsami.0c18674. Epub 2020 Dec 1.

Authors

Zeya Huang¹, Linhui Chen¹, Bing Huang¹, Biyi Xu², Gang Shao³, Hailong Wang³, Yutao Li², Chang-An Wang¹

Affiliations

¹ State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
² Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States.
³ School of Materials Science and Engineering, Zhengzhou University, Henan 450001, P. R. China.

PMID: 33259183
DOI: 10.1021/acsami.0c18674

Abstract

The application of Li-ion conducting garnet electrolytes is challenged by their large interfacial resistance with the metallic lithium anode and the relative small critical current density at which the lithium dendrites short-circuit the battery. Both of these challenges are closely related to the morphology and the structure of the garnet membranes. Here, we prepared four polycrystalline garnet Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) pellets with different particle sizes (nano/micro) and grain boundary additive (with/without Al₂O₃) to investigate the influence of grain size, the composition of the grain boundary, and the mechanical strength of the pellet on the total Li-ion conduction of the pellet, Li/garnet interfacial transfer, and lithium dendrite growth in all-solid-state Li-metal cells. The results showed that the garnet pellets prepared with nanoparticles and LiAlO₂-related grain boundary phase had decreased total Li-ion conductivity because of the increased resistance of the grain boundary; however, these pellets showed higher mechanical strength and improved capability to suppress lithium dendrite growth at high current densities. By controlling the grain size and optimizing the grain boundary with Al₂O₃ sintering additive, the hot-pressing sintered LLZTO solid electrolytes can reach up to 1.01 × 10^-3 S cm^-1 in Li⁺ conductivity and 0.29 eV in activation energy. LLZTO with nanosized grain and LiAlO₂-modified grain boundary showed the highest critical current density, which is 0.6 mA cm^-2 at room temperature and 1.7 mA cm^-2 at 60 °C. This study offers a useful guideline for preparing a high-performance LLZTO solid electrolyte.

Keywords: critical current density; garnet; grain boundary; hot pressing; solid electrolyte.