Phase field model coupling with strain gradient plasticity for fracture in lithium-ion battery electrodes

The fracture of the electrodes during the lithiation and delithiation is one of the primary reasons behind the short cycle life of the high-capacity lithium-ion batteries. In the present work, phase field method coupled with strain gradient plasticity is proposed to study the fracture of electrode particles used in lithium-ion batteries. The theoretical model is established by considering the effects of stress evolution, diffusion and crack growth. This approach is applied to electrode particles at the meso-micro scale. The results obtained from the MATLAB finite element analysis indicate that the equivalent plastic strain abruptly changes at the two-phase interface and accumulates at the crack tip. The crack becomes blunting and there is no obvious propagation trend. Due to these facts, the rate of lithiation declines. In addition, the shift of the two-phase interface towards the center decreases with the progression of lithiation. Further, the contribution of the strain gradient is found to be strengthened, which avoids the fracture and failure of the electrode particles.

Automated summary

In this study, the fracture of electrode particles in lithium-ion batteries was investigated using the phase field method and strain gradient plasticity model. The results showed that the crack becomes blunting, making it difficult to propagate, which leads to a decrease in the rate of lithiation. Meanwhile, the contribution of strain gradient helps to avoid fracture and failure.