Topochemical fluorination reactions in the context of fluoride ion batteries, tailored properties and for the modification of thin films

氟离子电池、定制特性和薄膜改性中的拓扑化学氟化反应

• 批准号: 285249272
• 负责人: Professor Dr. Oliver Clemens
• 金额: --
• 依托单位: Abteilung Chemische Materialsynthese
• 依托单位国家: 德国
• 项目类别: Independent Junior Research Groups
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/285249272?language=en
• 关键词: Topochemical; fluorination; reactions; context; fluoride

The project aims to investigate topochemical fluorination reactions of oxides within the perovskite type and similar structures (AxByOz, A = alkali or alkali earth, B = transition metal). This reaction type is of special interest in the fields of fluoride ion batteries, tailored material properties as well as thin film technologies. According to this, the project is structured in three subprojects. New electrochemical fluorination reactions are under concern in part (a). We aim to find and characterize new compounds which are capable for this type of reaction (e. g. SrFeO2--> SrFeO2F or LaSrMnO4 --> LaSrMnO4F2-d). To prove fluoride incorporation we aim to use Mössbauer as well as X-ray absorption spectroscopy in addition to XRD experiments. In contrast to chemical fluorination methods (XeF2, F2), electrochemical fluorination reactions can be expected to have the potential to adjust fluorine contents and average transition metal oxidation states (which play a crucial role on properties such as magnetism, conductivity, superconductivity) precisely. A special interest is located in the identification of compounds which are capable for reversible fluorine intercalation and deintercalation, which would facilitate building completely intercalation based fluoride ion batteries. In relation to part (a), chemical defluorination methods will be investigated in part (b) using reductive chemical agents (e. g. metal organic compounds, alkali metals) with oxyfluoride compounds. We target to invest the fluorination behavior of further materials, among them Bi1-xAxFeO3-y and La1 xSrxMnO3, where a strong change of material properties (magnetism, conductivity, ferroelectric properties) is to be expected and investigated. If fluorination of the latter systems will show to be reversible, the project will be additionally expanded towards electrochemically adjustable material properties. Investigation of ferroelectric properties requires the preparation of dense thin film oxyfluoride films. This is explained due to the fact that oxyfluorides are thermodynamically unstable and therefore cannot be sintered. We aim to investigate the fluorination and subsequent characterisation of thin perovskite films prepared by pulsed laser deposition in subproject (c). We will study the interplay between substrate strain and chemical strain due to fluorination on structure and properties of epitaxial grown films. In addition, thin porous fluorinated films will be investigated regarding their properties which are relevant for solid oxide fuel cell technologies (stability, conductivity, polarization resistances). Finally, we strive for theoretical validation of experimental results by means of DFT based calculations for all three subprojects.

该项目旨在研究钙钛矿型和类似结构（AxByOz，A =碱金属或碱土金属，B =过渡金属）内氧化物的局部化学反应。这种反应类型在氟离子电池、定制材料特性以及薄膜技术领域中具有特殊意义。据此，该项目分为三个分项目。在（a）部分中关注新的电化学氧化反应。我们的目标是发现和表征能够进行这种反应的新化合物（例如，G. SrFeO 2--> SrFeO 2F或LaSrMnO 4--> LaSrMnO 4F 2-d）。为了证明氟化物的掺入，我们的目标是使用穆斯堡尔以及X射线吸收光谱除了XRD实验。与化学还原方法（XeF 2，F2）相比，电化学还原反应有望精确调节氟含量和平均过渡金属氧化态（对磁性，导电性，超导性等性能起关键作用）。一个特别的兴趣是位于能够可逆的氟嵌入和脱嵌，这将有助于建立完全嵌入为基础的氟离子电池的化合物的鉴定。关于第（a）部分，将在第（B）部分中使用还原性化学试剂（e. G.金属有机化合物、碱金属）与氟氧化物化合物。我们的目标是投资进一步的材料，其中Bi 1-xAxFeO 3-y和La 1-xSrxMnO 3，其中材料性质（磁性，导电性，铁电性质）的强烈变化是预期和研究的超导行为。如果后者的系统将被证明是可逆的，该项目将进一步扩展到电化学可调材料性能。铁电性能的研究需要制备致密的氟氧化物薄膜。这是由于氟氧化物在化学上不稳定，因此不能烧结。我们的目标是研究子项目（c）中脉冲激光沉积制备的钙钛矿薄膜的沉积和后续表征。我们将研究由于异质结结构和外延生长薄膜的性质引起的衬底应变和化学应变之间的相互作用。此外，薄的多孔氟化膜将研究其性能，这是相关的固体氧化物燃料电池技术（稳定性，导电性，极化电阻）。最后，我们努力通过DFT为基础的计算为所有三个子项目的实验结果的理论验证。