We first present a model coupling the electrochemical reaction with strain gradient plasticity for a spherical electrode, which aims to analyze the evolutions and distributions of electrochemical-reaction dislocations and diffusion-induced stress during lithiation process. Several critical features viewed by in-situ TEM are incorporated into this model, such as the two-phase boundary and high-density dislocations at the reaction front. It is shown that the microstructure evolution can impact the mechanical properties and electrochemical performances of electrode materials. The results obtained by a finite difference method indicate that, as lithiation proceeds, the circumferential stress on the surface of the lithiated shell changes from compression to tensile stress, which may cause fracture of the active materials. Especially, the electrochemical-reaction dislocation zone results in fairly large stresses at the front of the interface. Furthermore, the lithiation reaction displays a strong size effect, and the movement rate of reaction front reduces as the size of the particles decreases. This work provides a framework for large-capacity, multi-scale research on high-capacity lithium-ion battery electrodes.

我们首先提出了一种将球形电极的电化学反应与应变梯度可塑性耦合的模型，旨在分析锂化过程中电化学反应位错和扩散诱发应力的演变和分布。原位观察的几个关键特征TEM被纳入该模型中，例如两相边界和反应前沿的高密度位错。结果表明，微观结构的演变会影响电极材料的力学性能和电化学性能。通过有限差分法获得的结果表明，随着锂化的进行，锂化壳表面上的周向应力从压缩应力变为拉伸应力，这可能导致活性材料破裂。特别地，电化学反应位错区在界面的前部产生相当大的应力。此外，锂化反应显示出强的尺寸效应，并且随着颗粒尺寸的减小，反应前沿的移动速率降低。这项工作为大容量提供了一个框架，