A Free Volume-Based Viscoplastic Model for Amorphous Silicon Electrode of Lithium-Ion Battery
A Free Volume-Based Viscoplastic Model for Amorphous Silicon Electrode of Lithium-Ion Battery
复制标题
锂离子电池非晶硅电极基于自由体积的粘塑性模型
DOI：
10.1149/1945-7111/ab75c0
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发表时间：
2020
影响因子：
3.9
通讯作者：
Fuqian Yang
中科院分区：
文献类型：
--
作者：
Yong Li;Wenya Mao;Qi Zhang;Kai Zhang;Fuqian Yang
硅从晶相到非晶相的相变，在前几次循环后形成Li12Si7，Li7Si3，Li13Si4和Li22Si5等亚稳非晶结构，表明硅基锂离子电池中硅主要以非晶相存在。本文将广泛应用于大块金属玻璃变形分析的自由体积理论推广到非晶Si电极在电化学循环过程中的循环诱导粘塑性变形，并建立了锂化Si中塑性流动的自由体积流动单元本构关系。锂化硅中的塑性流动伴随着自由体积的产生和湮灭。使用本构关系，并纳入锂化硅的浓度依赖性的机械性能，我们研究了循环引起的演化的柯西应力和自由体积在非晶，薄膜硅电极。数值计算结果与文献报道的实验结果雅阁较好，验证了非晶薄膜Si电极循环形变分析中所采用的近似方法。
The phase transition of Si from crystalline phase to amorphous phase with the formation of metastable amorphous structures of Li 12 Si 7, Li 7 Si 3, Li 13 Si 4 and Li 22 Si 5 after the first few cycles suggests that the Si in Si-based lithium-ion battery is mainly present in amorphous phase. In this work, we extend the free volume theory, which has been widely used in the deformation analysis of bulk metallic glass, to describe the cycling-induced visco-plastic deformation in amorphous Si-electrode during electrochemical cycling and establish a constitutive relationship with the flow unit of free volume for the plastic flow in lithiated Si. The plastic flow in lithiated Si is accompanied with the creation and annihilation of free volume. Using the constitutive relationship and incorporating the concentration-dependent mechanical properties of lithiated Si, we study the cycling-induced evolution of Cauchy stress and free volume in amorphous, thin-film Si-electrodes. The numerical results are in good accord with the experimental results reported in literature, which validates the approximation used in the analysis of the cycling-induced deformation of the amorphous, thin-film Si-electrodes.