Crash Simulation Analysis for Optimization of the Carbon Fiber Polymer Composite Pultruded Battery Separators

Abstract The design of battery packs has become a key factor influencing vehicle performance and safety. Current studies emphasize the role of Lithium-ion battery (LIB) separators in Electric Vehicles (EVs) and highlight the increasing occurrence of battery failures in vehicle crash conditions. The separators, positioned between the mounted battery packs attached to the vehicle floor, ensure structural stability and help mitigate potential hazards in crash scenarios. Additionally, they function as thermal and electrical insulators, preventing interactions between neighboring battery modules. At the same time, battery separators must remain lightweight to optimize energy efficiency. This paper focuses on predicting the loads on battery separators during simulated crash tests to determine the design boundary conditions for separators made of carbon fiber reinforced polymer composites (CFRP) and their manufacturing using pultrusion. The study includes numerical simulations to evaluate the bending and energy characteristics of various geometry profiles such as T-shape and hollow rectangle shape of the separators in a high-speed impact scenario such as crash. The preliminary design phase involves mechanical property testing and material validation using three-point bending and finite element simulations of rigid side-pole crash tests to predict bulk material behavior under different conditions. By comparing the performance of models with LIB-integrated separators, the study aims to incorporate simulation results for material selection, design, and the manufacturing of pultruded separators. T-shaped and hollow rectangular separators assembled into battery modules were investigated. For the same weight, the hollow rectangular separator absorbed 0.23 kJ more energy than the T-shaped separator. The bending behavior of the horizontal hollow rectangular separator was evaluated through a three-point bending test, revealing that a thickness of 4 mm provided better bending stiffness while maintaining a lightweight structure. Ultimately, this research focuses on analyzing a pultruded bulk separator that offers cost efficiency and effective mechanical properties, particularly in the context of rigid side-pole impact scenarios in EV crashes. It also explores optimization of wall thickness and web thickness.