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An analytic model for effective mechanical properties and local contact stresses in lithium-ion porous electrodes
Extreme Mechanics Letters ( IF 4.7 ) Pub Date : 2020-10-20 , DOI: 10.1016/j.eml.2020.101067
Peter Gudmundson , Per-Lennart Larsson

Explicit expressions for stress–strain relationships and swelling strains are derived for porous lithium-ion electrodes. Local contact stresses between neighboring electrode particles are also predicted. The analytical model is based on similar microstructural averaging techniques that previously have been applied to simulations of powder compaction. Both direct particle–particle and particle–binder–particlecontacts are considered. The model gives explicit dependencies of constituent material properties and parameters describing the microstructure geometry. Examples are presented for electrodes that have particle–particle contacts below the percolation limit. The prediction of the E-modulus shows good agreement with experimental results. Constrained swelling resulting from intercalation of lithium-ions has also been simulated. The resulting electrode stress state compares well with numerical predictions by the finite element and the discrete element method. Local particle–particle contact stresses of the order 1–6 GPa have as well been predicted. A simplified model using a model for rigid-plastic deformation of particles have shown that the stress–strain behavior during the first charging cycle may substantially differ from subsequent cycles, a phenomenon that also has been experimentally observed.



中文翻译:

锂离子多孔电极有效力学性能和局部接触应力的解析模型

得出了多孔锂离子电极应力-应变关系和溶胀应变的显式表达式。还可以预测相邻电极颗粒之间的局部接触应力。该分析模型基于类似的微结构平均技术,该技术先前已应用于粉末压实模拟。直接粒子间和粒子间的接触都被考虑了。该模型给出了组成材料属性和描述微观结构几何形状的参数的明确依赖性。给出了具有低于渗滤极限的颗粒间接触的电极的示例。E模量的预测与实验结果吻合良好。还模拟了由于嵌入锂离子而产生的约束膨胀。所得的电极应力状态与有限元法和离散元法的数值预测结果很好地比较。局部颗粒间的接触应力约为1-6 GPa。使用颗粒的刚塑性变形模型的简化模型表明,在第一个充电周期中的应力-应变行为可能与随后的充电周期有很大的不同,这种现象也已通过实验观察到。

更新日期:2020-12-02
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