Haarmann Lisette, Rohrer Jochen, Albe Karsten
Institut für Materialwissenschaft, Fachgebiet Materialmodellierung, Technische Universität Darmstadt, Otto-Berndt-Str. 3, Darmstadt D-64287, Germany.
ACS Appl Mater Interfaces. 2021 Nov 10;13(44):52629-52635. doi: 10.1021/acsami.1c15400. Epub 2021 Oct 28.
Understanding the nature of ion transfer at the interface between Li metal and solid electrolytes (SE) is essential for further optimization of all-solid-state Li-ion batteries. Thus, the Li transfer across the SE|Li metal interface is investigated by means of ab initio calculations based on density functional theory in this work. The aluminum-doped garnet LiAlLaZrO (LLZO) is considered as a model SE due to its practical stability against Li metal. A low-energy interface model in bicrystal geometry is constructed and investigated by nudged elastic band calculations as well as ab initio molecular dynamics (AIMD) simulations. In order to distinguish between interface and bulk transport in the AIMD simulations, a post-processing protocol is developed. We find that the activation energies and diffusivities of Li are comparable in bulk LLZO and across the interface, substantiating that the interface kinetics are not rate-limiting. Moreover, electronic structure analysis indicates that charge transfer occurs gradually. Finally, Al loss of LLZO at the interface rationalizes the experimentally observed phase transition from cubic to tetragonal observed close to Li metal contacts.
了解锂金属与固体电解质（SE）界面处离子转移的本质对于全固态锂离子电池的进一步优化至关重要。因此，在本工作中，基于密度泛函理论通过从头算计算研究了锂在SE|锂金属界面上的转移。由于铝掺杂石榴石LiAlLaZrO（LLZO）对锂金属具有实际稳定性，因此将其视为模型SE。通过推挤弹性带计算以及从头算分子动力学（AIMD）模拟构建并研究了双晶几何结构中的低能量界面模型。为了在AIMD模拟中区分界面传输和体相传输，开发了一种后处理协议。我们发现，锂在体相LLZO中和跨界面的活化能和扩散率相当，这证实了界面动力学不是速率限制因素。此外，电子结构分析表明电荷转移是逐渐发生的。最后，LLZO在界面处的铝损失解释了在接近锂金属接触处实验观察到的从立方相到四方相的相变。
