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.

中文翻译：

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固态电解质的阻抗建模：接触式空间电荷层的影响

理解固态电解质和电极之间的界面阻抗是固态电池设计的关键问题。我们提出了一种新的等效电路模型，该模型不仅将接口视为电容器，还包括空间电荷层电阻和所得极化电阻。此外，电路模型的元素是根据最近提出的改进的普朗克-能斯特-泊松（MPNP）模型通过物理量来量化的，其中包括空位规则晶格位点（空位）在电扩散问题中的影响以及考虑到离子和电子的贡献。我们为空间电荷层电容提供了一种新的分析解决方案。比较数值结果表明，我们提出的带有附加极化电阻的模型可以很好地解释纯电容器界面模型失效的低频区域的实际阻抗尾巴。针对LiPON的实验阻抗谱验证了该模型。