Kinetics of Li intercalation and de-intercalation in tantalum chalcogenide single crystals

钽硫族化物单晶中锂嵌入和脱嵌动力学

• 批准号: 167039484
• 负责人: Professor Dr. Harald Behrens
• 金额: --
• 依托单位: Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/167039484?language=en
• 关键词: Kinetics; Li; intercalation; de; tantalum

The kinetics of lithium intercalation in layered materials is poorly understood and will be systematically investigated in TP using chalcogenides as examples. Several steps are involved in the intercalation process and it is not known a priori which of them controls the rate of intercalation. In the first period of the project we have studied chemical intercalation of lithium in titanium chalcogenide single crystals. Major findings were that the insertion of lithium in these layered crystals is inhomogeneous, and local stress plays an important role. In the second period we want to study insertion of lithium in tantalum sulfides. In contrary to titanium chalcogenides, this compound is a good electrical conductor already before incorporation of lithium. Thus, both chemical and electrochemical intercalation can be studied on the same material, giving new insights to the mechanisms of processes relevant for charge and discharge of Li-batteries. Chemical intercalation will be performed by surrounding single crystals with a solution of n-buthyl lithium in hexane or heptane. For electrochemical intercalation experiments the set up will be modified using lithium metal as a second electrode and anhydrous lithium compounds as electrolytes. Depending on applied voltage lithium will be either inserted or removed from the crystals. After the experiments lithium profiles will be measured using laser ablation combined with mass spectrometry. Diffusion perpendicular to the layers will be studied using SIMS (secondary ion mass spectrometry). Distribution of lithium within layers can be observed using ToF-SIMS (time of flight - secondary ion mass spectrometry). Findings of our first studies have demonstrated that pressure has major influence on the kinetics of Li-intercalation. Chemical intercalation under hydrostatic pressure will be studied in gas pressure vessels after sealing of the sample assemblage in gold capsules. Both chemical and electrochemical intercalation will be studied under axial pressures of several kbars up to several tenths of kbar in a new cell developed during the first period of TP6. Additional parameters to be varied are temperature (20 - 80 °C), lithium concentration in the solutions and, in the case of electrochemical intercalation, voltage. Since different polymorphs of TaS2 can be synthesized by gas transport reactions and subsequent annealing or quenching, the influence of order of layers can be investigated as well.

锂嵌入层状材料中的动力学知之甚少，将在TP中以硫属化合物为例进行系统研究。在嵌入过程中涉及几个步骤，并且先验地不知道它们中的哪一个控制嵌入速率。在项目的第一阶段，我们研究了锂在钛硫族化合物单晶中的化学嵌入。主要的发现是，锂在这些层状晶体中的嵌入是不均匀的，局部应力起着重要的作用。在第二阶段，我们要研究锂在钽硫化物中的嵌入。与钛硫属化物相反，该化合物在掺入锂之前就已经是良好的电导体。因此，可以在同一材料上研究化学和电化学插层，为锂电池充电和放电相关过程的机制提供新的见解。化学嵌入将通过用正丁基锂的己烷或庚烷溶液包围单晶来进行。对于电化学嵌入实验，将使用锂金属作为第二电极和无水锂化合物作为电解质来修改设置。根据所施加的电压，锂将被插入晶体或从晶体中移除。在实验之后，将使用激光烧蚀结合质谱法测量锂分布。将使用西姆斯（二次离子质谱法）研究垂直于层的扩散。可以使用ToF-SIMS（飞行时间-二次离子质谱法）观察层内锂的分布。我们的第一个研究结果表明，压力对锂嵌入动力学有重大影响。将样品组合密封在金胶囊中后，将在气体压力容器中研究静水压力下的化学插层。在TP 6的第一阶段开发的新电池中，将在几千巴至几十千巴的轴向压力下研究化学和电化学嵌入。待改变的另外的参数是温度（20 - 80 °C）、溶液中的锂浓度以及在电化学嵌入的情况下的电压。由于TaS 2的不同多晶型可以通过气体传输反应和随后的退火或淬火来合成，因此也可以研究层的顺序的影响。