Huang Zeya, Chen Linhui, Huang Bing, Xu Biyi, Shao Gang, Wang Hailong, Li Yutao, Wang Chang-An
State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China.
Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States.
ACS Appl Mater Interfaces. 2020 Dec 16;12(50):56118-56125. doi: 10.1021/acsami.0c18674. Epub 2020 Dec 1.
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 LiLaZrTaO (LLZTO) pellets with different particle sizes (nano/micro) and grain boundary additive (with/without AlO) 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 LiAlO-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 AlO sintering additive, the hot-pressing sintered LLZTO solid electrolytes can reach up to 1.01 × 10 S cm in Li conductivity and 0.29 eV in activation energy. LLZTO with nanosized grain and LiAlO-modified grain boundary showed the highest critical current density, which is 0.6 mA cm at room temperature and 1.7 mA cm at 60 °C. This study offers a useful guideline for preparing a high-performance LLZTO solid electrolyte.
锂离子导电石榴石电解质的应用面临着挑战，即它们与金属锂负极之间存在较大的界面电阻，以及锂枝晶使电池短路时相对较小的临界电流密度。这两个挑战都与石榴石膜的形态和结构密切相关。在此，我们制备了四种具有不同粒径（纳米/微米）和晶界添加剂（有/无AlO）的多晶石榴石LiLaZrTaO（LLZTO）颗粒，以研究粒径、晶界组成和颗粒的机械强度对颗粒的总锂离子传导、Li/石榴石界面转移以及全固态锂金属电池中锂枝晶生长的影响。结果表明，用纳米颗粒和与LiAlO相关的晶界相制备的石榴石颗粒由于晶界电阻增加而使总锂离子电导率降低；然而，这些颗粒表现出更高的机械强度，并在高电流密度下具有更好的抑制锂枝晶生长的能力。通过控制粒径并使用AlO烧结添加剂优化晶界，热压烧结的LLZTO固体电解质的锂电导率可达1.01×10 S cm，活化能为0.29 eV。具有纳米尺寸晶粒和LiAlO改性晶界的LLZTO表现出最高的临界电流密度，室温下为0.6 mA cm，60℃时为1.7 mA cm。本研究为制备高性能LLZTO固体电解质提供了有用的指导。
