Next generation lithium-ion batteries (LIBs) cathodes are composed of polycrystalline microstructures where spatial heterogeneity such as grain size is often comparable to the geometric dimension of the cathodes. Incorporating the influence of the aforementioned heterogeneity in a chemo-mechanical continuum description is necessary to address the diffusion induced stress field during electrochemical cycling. Therefore, in the present study, the micro-structural size-dependent characteristic length of the cathode is embedded through a non-classical continuum mechanics approach known as the strain gradient elasticity (SGE) theory. Accordingly, a thermodynamically consistent multi-physics framework is developed where nonlinear diffusion kinetics is included along with the energetic interaction between the lithium-ions and host lattice of the electrode. The coupled governing equations are derived for the spherical cathode, and the generalized differential quadrature (GDQ) method is utilized to build the numerical procedure. The role of material heterogeneity length scale is addressed for strongly coupled chemo-mechanical process. Subsequently, the growth of potential surface flaws is examined under multiple length scales, particle size, and charge rate conditions. Ultimately, a comprehensive fracture map is established to illustrate the regime of flaw insensitivity, partial breakage and complete disintegration. Thus, the present findings can provide a suitable design perspective for fail-safe particulate type composite cathodes.

下一代锂离子电池（LIB）阴极由多晶微结构组成，其中空间异质性（例如晶粒尺寸）通常可与阴极的几何尺寸相媲美。为了解决电化学循环过程中由扩散引起的应力场，必须在化学机械连续描述中纳入上述异质性的影响。因此，在本研究中，通过一种称为应变梯度弹性（SGE）理论的非经典连续介质力学方法来嵌入阴极的与微观结构有关的特征长度。因此，建立了一个热力学一致的多物理框架，其中包括非线性扩散动力学以及锂离子和电极主体晶格之间的能量相互作用。导出了球形阴极的耦合控制方程，并利用广义微分正交（GDQ）方法建立了数值程序。解决了材料异质性长度尺度在化学机械过程中的强耦合问题。随后，在多个长度尺度，粒度和荷电率条件下检查了潜在的表面缺陷的生长。最终，建立了全面的断裂图以说明缺陷敏感性，局部断裂和完全崩解的状态。因此，