The operation of a Li-ion battery involves a concerted sequence of mass and charge transport processes, which are underpinned by alternating dilation/contraction of the active electrode materials. Several Li-ion battery failure mechanisms can be directly traced to lattice-mismatch strain arising from local compositional heterogeneities. The mechanisms of chemo-mechanical coupling that effect phase separation and the resulting complex evolution of internal stress fields remain inadequately understood. This work employs X-ray microscopy techniques to image the evolution of composition and stress across individual bent V₂O₅ particles. Experimental findings show that lattice strain imposed by the deformation of an individual cathode particle profoundly modifies phase separation patterns, yielding striated Li-rich domains ensconced within a Li-poor matrix. Particle-level inhomogeneities compound across scales resulting in fracture and capacity fade. Coupled phase field modeling of the evolution of domains reveals that the observed patterns minimize the energetic costs incurred by the geometrically imposed strain gradients during lithiation of the material and illustrate that phase separation motifs depend sensitively on the particle geometry, dimensions, interfacial energetics, and lattice incommensurability. Sharp differences in phase separation patterns are observed between lithiation and delithiation. This work demonstrates the promise of strain-engineering and particle geometry to deterministically control phase separation motifs such as to minimize accumulated stresses and mitigate important degradation mechanisms.

中文翻译：

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弯曲的好拍打坏的：锂化和脱锂时单个阴极颗粒的相分离模式

锂离子电池的操作涉及质量和电荷传输过程的协调顺序，这些过程通过交替扩展/收缩活性电极材料来加强。几种锂离子电池失效机制可以直接追溯到局部组成异质性引起的晶格失配应变。尚未充分了解影响相分离的化学机械耦合机理以及内部应力场的复杂演变。这项工作采用X射线显微镜技术来成像各个弯曲的V ₂ O ₅的成分和应力的演变粒子。实验结果表明，由单个阴极粒子变形引起的晶格应变会深刻地改变相分离模式，从而产生条纹状的富含锂的畴，该畴聚集在贫锂的基质中。各个尺度上的颗粒级不均匀性会导致断裂和容量衰减。区域演化的耦合相场建模表明，观察到的模式使材料在锂化过程中因几何施加的应变梯度而产生的能量成本最小化，并说明了相分离图案敏感地取决于粒子的几何形状，尺寸，界面能学和晶格不可通约性。在锂化和脱锂之间观察到相分离图案的尖锐差异。