Screen-Printed Carbon Nanotube Polymer Composites for Impact Sensing in Electric Vehicle Batteries

Abstract

Under-floor impacts are a major cause of thermal-runaway in EV battery packs, yet existing metal or MEMS sensors are heavy, costly, and cover only limited areas, leaving significant portions of the battery unmonitored. We introduce an ultralight, flexible, screen-printed carbon-nanotube (CNT)/epoxy patch sensor that detects impacts through piezoresistive resistance shifts. Conductivity increases with CNT loading, but impact sensitivity peaks at an intermediate CNT fraction and smaller print diameters, defining an optimal window of CNT content, print passes, and sensor footprint. Mounted on a prismatic 8 kWh module, the patches detected impacts ranging from 5–20 J within 20 ms, showcasing over tenfold improvement in strain sensitivity compared to conventional sensors, with negligible added mass. Furthermore, these sensors offer exceptional flexibility and adaptability, enabling their application across various complex battery pack geometries. These results demonstrate a scalable, practical route to comprehensive pack-level impact monitoring. Ongoing research will extend detection capabilities to impacts below 5 J and integrate artificial intelligence (AI) algorithms for mapping resistance signals to impact energy, precise location, and damage severity, paving the way for self-reporting battery-management systems capable of proactively preventing catastrophic failures. This advancement significantly enhances the safety, reliability, and operational efficiency of electric vehicles, promoting broader adoption and consumer confidence in EV technologies.