Evaluation method for mechanical fatigue damage of anode material of lithium-ion battery

Abstract

Lithium-ion battery (LIB) is widely used for mechanical structures such as electric vehicle. However, LIB easily leads to serious incidents because of its high energy density. Understanding mechanical properties of electrode materials is important in order to improve the safety of the LIB. On the other hand, little study has been done to fatigue test about electrode materials. This study has proposed a fatigue testing method for electrode materials by applying bending deformation repeatedly. The bending fatigue test was performed by using the anode material of the LIB that is carbon powder solidified with binder resin. Number of cycles to crack initiation at surface of anode material was defined as the fatigue life. Since it is difficult to measure directly the strain of the anode material, the strain model of specimen was proposed for evaluation the strain range under the bending fatigue test. The results of fatigue test and estimated strain range were summarized in S-N curve. The strain range of the anode material monotonically decreased against the number of cycles until the crack initiation.