Mechanical degradation analysis of a single electrode particle with multiple binder connections: A comparative study

Abstract

The binder constraint on the active particle is one of the reasons for the stress development at the electrode in Li-ion batteries. We systematically investigated the effect of the binder on the stress generation with three microstructure models featuring different numbers of binder connections. Using two-dimensional finite element simulations, we studied the effect of the number of binder connections on the evolution of the average state of charge (SOC) and the stress levels in the model systems during lithiation. The role of stress-concentration coupling was revealed for the lithium accumulation/deficiency and related stress development. The stress levels were further utilized for predicting the initiation of three potential failures: inner-particle fracture, binder yielding and particle-binder interface (PBI) debonding. The simulations revealed that particle-binder interfacial debonding and binder yielding are more likely to increase with more binder connections. The results provide fundamental insights that will support further optimization of the microstructures in the design of more robust electrodes for improved mechanical stability and performance.