Behaviour of battery separator under different charge rates according to poroelastodynamic model

A separator can influence the performance of a battery in several ways, and determining the mechanical response of the separator can allow to unveil the underlying reasons. We use quasi-static and fully dynamic poroelastic governing equations to simulate the separator of a lithium-ion battery under different charge/compression rates to characterise the displacements and pore pressure. The viscoelastic effect is also considered by adjusting the separator Young's modulus. Error analysis and independent mesh tests are used to validate the simulations. The numerical results show a wave pattern in the stress-strain curve of the separator when using the fully dynamic model, whereas this phenomenon cannot be observed when using the quasi-static model. The distribution of properties in the separator shows that the maximum displacement and pore pressure in the separator increase with the compression rate, and the pore pressure fluctuates during compression when using the fully dynamic model. The two variables in the poroelastodynamic model, namely, displacement and pore pressure, can establish an alternative for analysing battery separators. The simulation results provide a new insight into the separator behaviours and help one understand the battery performance degradation caused by separators better.

Automated summary

This study investigates the mechanical response of a battery separator and its impact on battery performance. Simulating the displacement and pore pressure of the separator under different charge/compression rates, it is found that the stress-strain curve of the separator exhibits a wave pattern in the fully dynamic model, while this phenomenon is not observed in the quasi-static model. The maximum displacement and pore pressure increase with the compression rate, and the pore pressure fluctuates during compression in the fully dynamic model.