Thin film batteries based on electrical-induced interface reactions

一种新型的锂离子薄膜电池将被研究，它显示出一种新颖的，自形成的反应层，而不是传统的电极。电池将通过反应离子束溅射法制备，使用一层超薄的众所周知的网络玻璃立磷酸盐(Lithium Pylous OxyNide)作为固体电解液。对于电极的沉积，将采用一种新的、另一种概念：在LiPon与传统金属的界面上，通过固相反应形成电化学活性界面相。该相作为阴极侧的活性物质，因此不再需要传统的插层阴极沉积。目前，对这种界面相的生长过程和性质的研究还很少。然而，最近的文献和自己的工作结果表明，它具有新颖的电化学性质，有助于提高薄膜电池的能量密度和循环稳定性。因此，在项目的第一步，应该从基本的角度研究这种电化学活性相的生长过程和性质，在模型体系为铂-立邦-银的情况下。应调查发生哪些界面反应以及这些反应以何种方式影响电池的存储容量和循环稳定性。为此，将使用透射电子显微镜、循环伏安法和阻抗谱来详细研究界面反应。在这些基础研究的基础上，提出了提高新型薄膜电池的能量密度和循环稳定性的概念。为此，将对新材料进行测试。在阴极一侧，计划使用例如铁、钴、镁或钒，这可能导致能量密度增加。相反，在负极一侧将使用一层薄薄的锂钛氧化物，这可能会增强电池的循环稳定性。

A new class of lithium ion thin film batteries will be studied, which exhibits a novel, self-forming reaction layer instead of conventional electrodes. The batteries will be prepared by reactive ion-beam sputtering, using an ultra-thin layer of the well-known network glass LIPON (Lithium Phosphorous Oxynitride) as a solid electrolyte. For deposition of the electrodes a novel, alternative concept will be applied: At the interface between LIPON and a conventional metal, an electrochemical-active interface phase is formed by solid state reaction. This phase serves as an active material on the cathode side, so the deposition of a conventional intercalation cathode is not necessary any more.Currently, the growth process and the properties of this interface phase are only poorly investigated. Nevertheless, recent results of literature and of own work show that it exhibits novel electrochemical properties and that it may help to increase the energy density and the cycle stability of the thin film batteries. Therefore, in a first step of the project, the growth process and the properties of this electrochemical-active phase shall be studied from a fundamental point of view, in case of the model system Pt-LIPON-Ag. It shall be investigated which interface reactions occur and in which way these reactions influence the storage capacity and the cycle stability of the batteries. For this purpose, transmission electron microscopy, cyclic voltammetry, and impedance spectroscopy will be used to investigate the interface reactions in detail. Based on these fundamental studies, a concept shall be developed, to improve the energy density and the cycle stability of the new thin film batteries. For this purpose, new materials will be tested. On the side of the cathode, the use of e.g. Fe, Co, Mg, or V is planed, which may result in an increased energy density. Instead, on the side of the anode, a thin layer of lithium titanium oxide will be used, which may enhance the cycle stability of the batteries.