The insertion of Li-ions within cathode materials during the discharging of a battery oftentimes brings about one or more structural transformations. The spatiodynamic propagation of phase transformations within a matrix of particles is determined by highly localized intercalation phenomena rather than the global voltage profile. Multiscale inhomogeneities resulting from variations in electrode reactions strongly influence the proportion of actively intercalating electrode materials, define local “hot-spots” wherein the current is greatly amplified during charge/discharge processes, and consequently dictate localized energy dissipation profiles. Multiphasic domains further give rise to localized stress gradients that can induce electrode degradation. However, a clear picture of chemical and stress inhomogeneities remains to be developed for most cathode materials. Here we demonstrate compositional striping modulations between Li-rich and Li-poor domains along the edges of individual nanowires of Li-ion-intercalated V₂O₅ based on analysis of hyperspectral X-ray microscopy data. Analysis of scanning transmission X-ray microscopy data using singular value decomposition and principal component analysis provides a means to map compositional inhomogenieties across individual nanowires and ensembles of nanowires alike. The compositional maps are further transformed to stress and strain maps, which depict the localization of tensile stress and strain within individual nanowires of Li_xV₂O₅. The core–shell and compositional striping modulations manifested here and the resulting strain gradients point to the need to design cathode materials and electrode architectures to mitigate such pronounced local inhomoegeneities in Li-ion intercalation and diffusion.

中文翻译：

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锂化过程中阴极材料单个颗粒内的条带调制和应变梯度†

在电池放电期间，锂离子在阴极材料中的插入经常引起一种或多种结构转变。粒子矩阵内相变的时空传播是由高度局部的插层现象而不是全局电压分布决定的。由电极反应变化引起的多尺度不均匀性会强烈影响有源插层电极材料的比例，定义局部“热点”，其中在充电/放电过程中电流会大大放大，因此决定了局部能量消散曲线。多相域进一步引起局部应力梯度，该局部应力梯度可引起电极退化。然而，对于大多数阴极材料来说，化学和应力不均匀性的清晰图景尚待开发。在这里，我们展示了富锂域和贫锂域之间沿着锂离子嵌入V的单个纳米线的边缘的成分条带调制₂ O ₅基于对高光谱X射线显微镜数据的分析。使用奇异值分解和主成分分析对扫描透射X射线显微镜数据进行分析，提供了一种手段，可以绘制跨单个纳米线和纳米线集合体的成分不均一性。成分图进一步转换为应力图和应变图，该图描述了Li _x V ₂ O _5的各个纳米线内的拉伸应力和应变的定位。。此处显示的核-壳和成分条纹调制以及由此产生的应变梯度表明，需要设计阴极材料和电极体系结构，以减轻锂离子嵌入和扩散中这种明显的局部不均匀性。