Lithiated metallic anodes (LixSn1-x) with internal Ga-rich liquid matrix for rechargeable lithium ion batteries

新一代锂离子电池具有比目前技术水平的电池所表现出的明显更高的电荷密度和循环稳定性，这主要受到缺乏合适的可逆负电极材料的阻碍。与使用商业碳负极相比，通过使用基于例如，Sb、Si和Sn。虽然这些材料表现出明显更高的充电容量，但它们在电化学循环期间遭受大的体积摆动，这导致电极材料的分解，并因此失去活性颗粒之间的电接触。高度关注最近发表的研究，其中纯Ga作为阳极材料的常规自愈效应被证明可以同时治愈膨胀引起的裂纹。当前提议的动机是设计具有低熔点富Ga相作为内部基质的第一异质Sn基阳极材料。除了通常耗时和昂贵的原型电极材料的评估，战略将采用直接相关的热化学性质，平衡图和电化学使用的CALPHAD方法，这是迄今为止最先进的方法热力学建模和优化的复杂的非均相系统。GaxSn 1-x阳极材料的精心设计将通过基于合适的关键实验的Ga-Li-Sn系统的热力学描述的同时改进来补充。重点将是根据晶体学现有信息，基于定义良好的亚晶格模型的非化学计量化合物的准确描述。对实际嵌入材料的晶格内的缺陷机制和位置占据的可靠描述也将提高对其他金属间化合物材料中的锂化过程的理解，并且可能启发用于Li离子电池的新反应机制的设计。在整个工作过程中，将设计具有良好宏观性能的适当阳极材料，并对锂化机理进行精确预测。GaxSn 1-x电极的电化学循环测试将用于验证先前的计算预测，并通过迭代数据生成和评估过程提供有关建模改进的信息。所提出的方法将允许扩展到任何感兴趣的金属间阳极材料，以实现基础材料研究和先进材料应用之间的更紧密联系。

The new generation of lithium ion batteries with distinctly higher charge densities and cycling stabilities than exhibited by todays state of the art cells is predominantly hindered by the lack of suitable reversible negative electrode materials. A new approach compared to the use of commercial carbon negative electrodes has been established rather early by the use of intermetallic anode materials based on e.g., Sb, Si and Sn. While these materials express significant higher charge capacities they suffer from large volume swings during electrochemical cycling which cause disintegration of the electrode material and hence loss of electrical contacts between active particles. High attention was given to a recently published study where a regular self-healing effect of pure Ga as anode material was demonstrated which can simultaneously heal the expansion induced cracks. The motivation of the current proposal is to design the first heterogeneous Sn based anode material with a low melting Ga-rich phase as an internal matrix. Apart from usually time-consuming and expensive evaluations of prototype electrode materials, strategies will be employed to directly correlate thermochemical properties, equilibrium diagrams and electrochemistry by using the CALPHAD method which is up to now the most advanced method for thermodynamic modeling and optimization of complex heterogeneous systems. A careful design of GaxSn1-x anode materials will be supplemented by a simultaneous improvement of the thermodynamic description of the Ga-Li-Sn system based on suitable key experiments. In focus will be the accurate description of non-stoichiometric compounds based on well-defined sublattice models according to crystallographical available information. The reliable description of defect mechanisms and site occupations within the crystal lattice of the actual insertion materials will improve also the understanding of the lithiation process in other intermetallic materials and may inspire the design of new reaction mechanisms for Li ion batteries. Throughout the work, proper anode materials with well-defined macroscopic properties will be designed and exact predictions of the lithiation mechanism will be made. Electrochemical cycling tests of GaxSn1-x electrodes will be used for verifying previous predictions from the calculations as well as provide information on modeling improvements through an iterative data generation and evaluation process. The proposed approach will allow the extension to any intermetallic anode material of interest to achieve a closer connection between basic materials research and advanced materials application.