Degradation Evaluation on the Mechanical Properties of Composite Electrode Through an Integrated Phase Field and Continuum Simulation

Abstract

The electrochemical degradation phenomena in lithium-ion batteries imply that the mechanical properties of a composite electrode may deteriorate during cycling, however, there are still lack of detail information on their direct correlations. Here, we proposed an integrated phase field-continuum simulation method to track the process of mechanical degradation. Based on scanning electron microscope images of a composite electrode, a representative volume element microstructural model was constructed and the onset of damage and its evaluation caused by lithiation and delithiation were estimated though the phase-field method. Then a subsequent continuum mechanical model was performed on meso-structures with damage to evaluate their mechanical properties. The results show that damage primarily occurs during the initial cycle, and decreasing particle sizes and the cycling rate can effectively mitigate damage. This work bridges the relationship between the particle damage and mechanical properties of composite electrodes, and thus, provides important insights on their stress evaluation and optimal design in service.

Keywords: Degradation evaluation, mechanical properties, phase field method, composite electrode, lithium-ion batteries