Evaluation of Mechanical Integrity of Electrode Material in Lithium-ion Battery (LiB)

Abstract

Electrode sheet of lithium-ion battery (LiB) has a layered structure consisting of an active material layer (composite of binder and active material) and a current-collecting layer (metallic foil). One of the problems against mechanical loading is cracking in binder due to a manufacturing process and charge-discharge cycle. This leads to shorten battery life and reduce electrical capacity. In addition, exfoliation from a current-collecting layer is also critical issue during charge-discharge cycle. This study first investigated that microcrack occurs around particle of active material due to the stress concentration. For the microstructural design of the active material layer, finite element method (FEM) was carried out. In this study, the damage criterion was employed to FEM in order to simulate crack propagation in binder with particles of active material. Due to non-linear plastic deformation of binder, this criterion is established based on accumulative strain increment. We simulated microcrack propagation in active material layer subjected to uni-axial tension. The validity of the crack simulation was conducted by comparison of actual experiment. This kind of mechanical integrity evaluation may be useful for electrode design for material and integrity of aged electrode after charge-discharge cycle.