Abstract Amorphous lithium metal alloys (Li x M, with M=Si, Ge, Sn, …) are attractive anode materials for lithium-ion batteries owing to their high energy-storage capacity and safety characteristics. However, repeated insertion of lithium often leads to chemo-mechanical degradation of the alloy, which can severely reduce the battery capacity and cycle life. Better understanding of the chemo-mechanical response of lithium alloys is needed to guide the design of damage-resistant anode microstructures. In this work, we propose a constitutive theory that couples large, viscoplastic deformations to the insertion and extraction of lithium in amorphous electrode materials. The theory relies on the concept of Shear Transformation Zone as carrier of plastic flow in the amorphous material, and accounts for microstructural evolution via an internal “free volume” variable. The model is used to gain insight into several features of the plasticity of amorphous alloys during lithiation, including rate-dependency, pressure-dependency, and structural evolution. Model predictions are also compared to experimental data for amorphous silicon.

中文翻译：

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锂离子电池非晶负极材料中锂嵌入和粘塑性流动的耦合理论

摘要 无定形锂金属合金（Li x M，其中 M=Si、Ge、Sn 等）由于其高储能容量和安全特性而成为极具吸引力的锂离子电池负极材料。然而，锂的反复插入往往会导致合金的化学机械降解，这会严重降低电池容量和循环寿命。需要更好地了解锂合金的化学机械响应，以指导抗损伤阳极微结构的设计。在这项工作中，我们提出了一种本构理论，该理论将大的粘塑性变形与非晶电极材料中锂的插入和脱嵌相结合。该理论依赖于剪切转变区的概念作为非晶材料中塑性流动的载体，并通过内部“自由体积”变量解释微观结构演变。该模型用于深入了解锂化过程中非晶合金塑性的几个特征，包括速率依赖性、压力依赖性和结构演化。模型预测也与非晶硅的实验数据进行了比较。