Numerical optimization of the spatial conductivity distribution within cathode microstructures of lithium‐ion batteries considering the cell performance
Numerical optimization of the spatial conductivity distribution within cathode microstructures of lithium‐ion batteries considering the cell performance
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DOI：
10.1002/er.3794
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发表时间：
2017-11
影响因子：
4.6
通讯作者：
M. Kespe;M. Gleiß;Simon Hammerich;H. Nirschl
中科院分区：
文献类型：
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作者：
M. Kespe;M. Gleiß;Simon Hammerich;H. Nirschl
提出了一种优化锂离子电池三维电极微结构内空间电导率分布的数值方法。它的方法是基于锂离子电池半电池在颗粒尺度上的空间分辨三维电化学模型。尽管该方法独立于下面的电极微结构，但是该方法被示例性地应用于由光滑球形颗粒组成的计算机生成的周期性电极结构。在第一步中，通过改变参数来研究电导率对模拟的半电池性能的影响。模拟表明，低电导值的性能限制效应可以归因于局部插层磁通密度的穿透平面方向的不均匀。此外，研究还表明，如果达到均匀的表面嵌入通量密度，进一步增加空间均匀的电导率并不会导致更好的半电池性能。在第二步中，确定的最佳空间均匀电导率值作为空间优化方法的基础。由此得到的电极内的导电结构显示出垂直于电极表面的类似梯度的行为，而最高的电导值预计在靠近集电体的区域内。因此，建议采用多层涂层作为一种实用的制造方法。由于所提出的两阶段优化方法，所得到的导电结构在不改变宏观电池性能的情况下显示出了导电节约的潜力。
A numerical approach targeting the optimization of the spatial conductivity distribution within a three‐dimensional electrode microstructure of lithium‐ion batteries is presented. Its methodology is based on a spatially resolved three‐dimensional electrochemical model of a lithium‐ion battery half cell on the particle scale. Although being independent of the underlying electrode microstructure, the method is exemplarily applied on a computer‐generated periodic electrode structure consisting of smooth spherical particles. In the first step, parameter variations are performed to investigate the influence of the electrical conductivity on the simulated half‐cell performance. The simulations show that the performance‐limiting effect of low electrical conductivity values can be attributed to a through‐plane directed inhomogeneity of the local intercalation flux density. Furthermore, it is shown that if a homogenous surface intercalation flux density is reached, a further increase of the spatially uniform conductivity would not result in better half‐cell performance. In the second step, the determined optimum spatially uniform conductivity value is taken as a basis for the spatial optimization approach. The resulting conductive structure within the electrode shows gradient‐like behavior directed perpendicular to the electrode surface, while highest conductivity values are to be expected in the region close to the current collector. Therefore, multiple layer coating is suggested as a suitable practical manufacturing approach. Due to the proposed two‐stage optimization approach, the resulting conductive structure reveals conductivity saving potential without altering the macroscopic cell performance.