Abstract
Internal short circuits and thermal runaway in lithium-ion batteries (LIBs) are mainly caused by deformation-induced failures in their internal components. Understanding the mechanisms of mechanical failure in the internal materials is of much importance for the design of LIB pack safety. In this work, the constitutive behaviors and deformation-induced failures of these component materials were tested and simulated. The stress-strain constitutive models of the anode/cathode and the separator under uniaxial tensile and compressive loads were proposed, and maximum tensile strain failure criteria were used to simulate the failure behaviors on these materials under the biaxial indentations. In order to understand the deformation failure mechanisms of ultrathin and multilayer materials within the prismatic cell, a mesoscale layer element model (LEM) with a separator-cathode-separator-anode structure was constructed. The deformation failure of LEM under spherical punches of different sizes was analyzed in detail, and the results were experimentally verified. Furthermore, the n-layer LEM stacked structure numerical model was constructed to calculate the progressive failure mechanisms of cathodes and anodes under punches. The results of test and simulation show the fracture failure of the cathodes under local indentation will trigger the failure of adjacent layers successively, and the internal short circuits are ultimately caused by separator failure owing to fractures and slips in the electrodes. The results improve the understanding of the failure behavior of the component materials in prismatic lithium-ion batteries, and provide some safety suggestions for the battery structure design in the future.
Highlights
If an electric vehicle was involved in an accident or might run continuously on rough road surfaces, its lithium-ion batteries (LIBs) would be subjected to complex external mechanical loads, which could lead to some degree of deformation
According to the recent studies [1,2,3], different mechanical failure conditions of LIBs resulted in significantly different electrical-thermal responses, for example, Cannarella et al [4,5] found that the LIBs manufactured with higher levels of stack pressure exhibited shorter cycle lives, because the higher levels of mechanical stress led to higher rates of chemical degradation, which affected the state of health (SOH) and state of charge (SOC) of the LIBs
The results showed that the external mechanical loading enlarged stresses and deformation generated in the electrode materials, which led to the premature mechanical failure of LIBs after certain cycles
Summary
If an electric vehicle was involved in an accident or might run continuously on rough road surfaces, its lithium-ion batteries (LIBs) would be subjected to complex external mechanical loads, which could lead to some degree of deformation. Wierzbicki et al [23] proposed a method for modeling 18,650 cylindrical lithium-ion cells based on representative volume elements (RVEs), which allows the stress-strain relationship of cells under local indentation to be obtained by analyzing the mechanical properties of the RVE. These model-based approaches are capable of predicting the mechanical behaviors of LIBs under mechanical loads, but unable to characterize their internal failure modes accurately. The layered structure model of the n-layer LEM stacked was constructed, and the progressive failure mechanisms of cathodes and anodes under spherical punch were studied
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
