Liu Yao, Bai Yang, Jaegermann Wolfram, Hausbrand René, Xu Bai-Xiang
Mechanics of Functional Materials Division, Department of Materials Science, TU Darmstadt, Otto-Berndt-Straße 3, 64287 Darmstadt, Germany.
Surface Science Division, Department of Materials Science, TU Darmstadt, Otto-Berndt-Straße 3, 64287 Darmstadt, Germany.
ACS Appl Mater Interfaces. 2021 Feb 3;13(4):5895-5906. doi: 10.1021/acsami.0c22986. Epub 2021 Jan 22.
Understanding the interfacial impedance between the solid electrolyte and the electrode is a critical issue for the design of solid-state batteries. We propose a new equivalent circuit model that treats the interface not only as a capacitor but also includes the space charge layer resistance and the resultant polarization resistance. Moreover, the elements of the circuit model are quantified by the physical quantities based on the recently proposed modified Planck-Nernst-Poisson (MPNP) model, which includes the effect of the unoccupied regular lattice sites (vacancies) in the electro-diffusion problem and takes both the ion and electron contributions into the account. We provide a new analytical solution for the space charge layer capacitance. Comparative numerical results demonstrate that our proposed model with additional polarization resistance can explain well the real impedance tail at the low-frequency region, for which the pure capacitor interface model fails. The model is verified against the experimental impedance spectra of LiPON.
理解固体电解质与电极之间的界面阻抗是固态电池设计中的一个关键问题。我们提出了一种新的等效电路模型，该模型不仅将界面视为一个电容器，还包括空间电荷层电阻和由此产生的极化电阻。此外，基于最近提出的修正普朗克 - 能斯特 - 泊松（MPNP）模型，通过物理量对电路模型的元件进行了量化，该模型在电扩散问题中考虑了未占据的规则晶格位点（空位）的影响，并兼顾了离子和电子的贡献。我们给出了空间电荷层电容的一种新的解析解。对比数值结果表明，我们提出的具有附加极化电阻的模型能够很好地解释低频区域的实际阻抗尾，而纯电容器界面模型在此处失效。该模型通过磷酸锂镧钽氧（LiPON）的实验阻抗谱得到了验证。
