晶界
微晶
材料科学
锂(药物)
离子
扩散
无定形固体
化学物理
快离子导体
电解质
密度泛函理论
晶界扩散系数
结晶学
化学
热力学
计算化学
物理化学
微观结构
冶金
物理
医学
有机化学
电极
内分泌学
作者
Jiahao Cui,Lingchen Meng,Shan Jiang,Kangping Wang,Jingyu Qian,Xiyang Wang
摘要
Lithium-ion diffusion ability in solid electrolytes is crucial for the performance and safety of lithium-ion batteries. However, the lithium-ion diffusion coefficient of Li6.75La3Zr1.5Ta0.5O12 (LLZTO) measured experimentally is much lower than that simulated theoretically because LLZTO exists widely in the polycrystalline form rather than in the single-crystal form. Herein, we focus on the construction of grain boundaries in polycrystalline materials to address this key issue. An amorphous structure is created by randomly throwing atoms into a virtual box, where the chemical bonds are broken and rearranged through continuous heating and annealing operations, resulting in a stable framework structure. The lithium-ion diffusion coefficients of polycrystalline LLZTO and single-crystal LLZTO calculated via Ab initio molecular dynamics (AIMD) are consistent with the experimental data in trend. Furthermore, the analysis of the grain boundary composed of the secondary phase in polycrystalline LLZTO reveals that the continuous -O-M-O- metal oxide grid with low formation energy per atom restricts the lithium-ion migration. The lithium-ion migration barriers calculated utilizing density functional theory (DFT) also demonstrate the obstacle of the grain boundary from another perspective.
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