Mechanical Damage Analysis of Prismatic Lithium-Ion Batteries Under the Coupling Effect of Loading Orientation and Electrical Aging

Abstract

The new energy vehicle (NEV) industry is expanding globally, yet safety accidents induced by collisions have become a major challenge to its high-quality development. In addition, the risks associated with battery state variations from fast-charging cycling cannot be ignored. To investigate the coupled effects of electrochemical degradation and mechanical loading on battery safety, a series of cross-factor-controlled mechanical experiments has been proposed based on 12 prismatic lithium-ion batteries across three aging states and two loading directions. The results indicate that the difference in loading orientation affects the mechanical safety responses. Under horizontal loading, interlayer slip dissipates the impact energy, and damage is concentrated in a localized area. In contrast, vertical loading is prone to inducing penetration-type damage to the structure, characterized by large-scale interlayer slip and multi-point separator damage. Moreover, once thermal runaway is triggered under vertical loading, the peak surface temperature is significantly higher. Loading orientation exerts an influence on the load-bearing capacity under mechanical damage, while electrochemical aging further reduces the safety margin of the batteries. The coupling effect of these two factors exacerbates the risk of impact failure. Consequently, if testing is based solely on fresh batteries, it tends to overestimate the safety boundary of in-service batteries. These results provide theoretical and data support for optimizing the structural design of battery systems, which is of great significance for the high-quality advancement of the NEV industry.