Investigation of mechanical property of cylindrical lithium-ion batteries under dynamic loadings

Abstract

Understanding of mechanical property of lithium-ion batteries is the key to unlock complicated and coupled behaviors of thermal runaway, which is triggered during electric vehicle collision. In this study, mechanical behaviors of cylindrical lithium-ion batteries under dynamic loadings are investigated. Two types of 18650 lithium-ion batteries, namely LiNiCoAlO2 and LiNiCoMnO2, are chosen to perform compression tests at various dynamic loadings. Experimental results indicate that these two types of 18650 lithium-ion batteries exhibit strain rate hardening behaviors, namely their resistances to deformation enhance as loading rate increases. LiNiCoMnO2 batteries show obvious strain rate hardening behaviors at low loading rates while LiNiCoAlO2 batteries can only show strain rate hardening behaviors until the loading rate increases to a certain value. The constitutive model of the jellyroll of lithium-ion batteries is proposed to describe these mechanical behaviors under dynamic loadings and it is validated by a finite element model of lithium-ion batteries. The proposed constitutive model can be utilized to evaluate the crashworthiness of lithium-ion batteries in the case of impact accidents and provide valuable guidance for the structure design of battery packs in electric vehicles.