Thermodynamics and kinetics of lithiation and delithiation of high capacity anode materials at elevated temperatures

在当今的锂离子电池中，温度管理是昂贵且耗能的必需品。锂离子电池中的大多数有机溶剂和凝胶基电解质在60°C以上是不稳定的，并且具有固有的灾难风险，必须通过额外的技术特征来降低。最有前途的高容量阳极材料如硅和锡的容量超过石墨10倍，但锂化和脱锂过程的可逆性较差。由于热力学和动力学的限制，锂化和脱锂过程的顺利和均匀受到阻碍。（Clausthal Zellerfeld），Rettenmayr教授（耶拿），宋教授（北京），并通过他们与纽介堡（杜塞尔多夫），我们的目标是开发一种锂离子电池系统，其将在高温（60 ℃-200 ℃）下使用高容量阳极材料的锂化和脱锂。因此，通过改变温度和材料结构和组成，我们将能够用两种基本方法研究锂化过程中尚未理解的相变：1.核磁共振，这是目前唯一的方法来检测在散装材料中的锂的局部环境的变化。2.通过原子探针分析以允许以原子分辨率检测这些材料的组成。在此基础上，建立热力学和动力学模型，揭示锂化和脱锂过程中的相变。我们的最终目标是使用来自现实检查动力学和热力学模型的预测，开发一种高容量的阳极材料，而不受当前可逆性的限制。最终，我们将实现一种电池系统，该系统可以在高温下可靠地使用，并且不依赖于当今电动汽车应用电池中使用的复杂温度管理系统。

Temperature management is a costly and energy consuming necessity in today’s Liion batteries. The majority of organic solvent and gel based electrolytes in Li-ion batteries is instable above 60°C and carries an inh erent risk for disaster, which has to be reduced by additional technological features.The most promising high capacity anode materials like silicon and tin outperform graphite by a factor of 10 in capacity, but show rater poor reversibility of the lithiation and delithiation process. A smooth and uniform lithiation and delithiation is hindered by unfortunate thermodynamics and kinetic limitations.In close cooperation with the theory-oriented workgroups Prof. Schmid-Fetzer (Clausthal Zellerfeld), Prof. Rettenmayr (Jena), Prof. Song (Beijing) and through them also with Neugebauer (Düsseldorf), we aim to develop a Li-ion battery system, which will use lithiation and delithiation of high capacity anode materials at elevated temperatures (60°C-200°C). Thus, by variation of te mperature and material structure and composition, we will be able to investigate the yet not understood phase changes during the lithiation process with two essential methods: 1. by NMR, which is currently the only method to detect changes in the local environment of lithium in bulk materials. 2. by atomic probe analysis to allow detection of the composition of these materials with atomic resolution. On this base, thermodynamic and kinetic models will be built, to shed light on phase changes during lithiation and delithiation. Our final goal is to use the predictions, derived from the reality checked kinetic and thermodynamic modeling, to develop a high capacity anode material without the current limitations on reversibility. In the far end, we will reach a battery system that can be reliably used at elevated temperatures and would not rely on a complex temperature management system used in today’s batteries for electro mobility applications.