Sun Yifei, Gorobstov Oleg, Mu Linqin, Weinstock Daniel, Bouck Ryan, Cha Wonsuk, Bouklas Nikolaos, Lin Feng, Singer Andrej
Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14850, United States.
Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.
Nano Lett. 2021 Jun 9;21(11):4570-4576. doi: 10.1021/acs.nanolett.1c00315. Epub 2021 Apr 29.
All-solid-state lithium batteries promise significant improvements in energy density and safety over traditional liquid electrolyte batteries. The Al-doped LiLaZrO (LLZO) solid-state electrolyte shows excellent potential given its high ionic conductivity and good thermal, chemical, and electrochemical stability. Nevertheless, further improvements on electrochemical and mechanical properties of LLZO call for an in-depth understanding of its local microstructure. Here, we employ Bragg coherent diffractive imaging to investigate the atomic displacements inside single grains of LLZO with various Al-doping concentrations, resulting in cubic, tetragonal, and cubic-tetragonal mixed structures. We observe coexisting domains of different crystallographic orientations in the tetragonal structure. We further show that Al doping leads to crystal defects such as dislocations and phase boundaries in the mixed- and cubic-phase grain. This study addresses the effect of Al doping on the nanoscale structure within individual grains of LLZO, which is informative for the future development of solid-state batteries.
全固态锂电池有望在能量密度和安全性方面比传统液体电解质电池有显著提升。铝掺杂的锂镧锆氧化物（LLZO）固态电解质因其高离子电导率以及良好的热稳定性、化学稳定性和电化学稳定性而展现出优异的潜力。然而，要进一步改善LLZO的电化学和力学性能，需要深入了解其局部微观结构。在此，我们采用布拉格相干衍射成像技术来研究不同铝掺杂浓度的LLZO单晶粒内部的原子位移，结果得到了立方结构、四方结构以及立方 - 四方混合结构。我们在四方结构中观察到了不同晶体取向的共存畴。我们还进一步表明，铝掺杂会导致混合相和立方相晶粒中出现诸如位错和相界等晶体缺陷。本研究阐述了铝掺杂对LLZO单个晶粒内纳米级结构的影响，这对固态电池的未来发展具有参考价值。
