Due to recent rapid advancements in high-energy storage batteries such as lithium-ion (Li-ion) batteries, electric vehicles are receiving more and more attention in both automotive and aviation industries. However, those high-energy batteries are often susceptible to mechanical intrusion and deformation, along with thermal runaway. Typical battery packs are therefore compounded by layer upon layer of vehicle level mechanical enclosures and protection systems to guard the cells and provide mechanical stability while maintaining intimate contact between the functional components. In addition, there is a lack of reliable prediction methods for battery state of health (SOH) and remaining service life (RSL) which leads to significant conservation in battery energy capacity design. These overhead components significantly reduce both the packing factor and the system-level energy density. For example, in state-of-the-art EVs, the weight and volume of the complete energy storage ‘system’, including protection systems and enclosures, can be as much as twice those of the cells alone. Additionally, the advantages of high-energy cells are also largely offset by the complexity and cost of the more demanding system-level engineering requirements.
In this presentation, we introduce a new multifunctional energy storage composite (MESC) for the design of battery-power electrical vehicles. MESC is made of high-strength carbon-fiber composites embedded with lithium-ion battery materials and built-in piezoelectric sensors. A novel interlocking fabrication technique is developed to seamlessly integrate lithium-ion batteries in composites without sacrificing the structural integrity of the host while maintaining the energy capacity and electrical performance of the original battery materials. At the same time, the SOH of the integrated batteries can be monitored accurately simultaneously using the built-in sensor networks in the composites. Prototypes of the multifunctional energy-storage composites have been fabricated and demonstrated the feasibility of potentially providing up to 40% weight savings on the combined battery and structural weight of existing commercial electric vehicles.
Fu-Kuo Chang is a Professor in the Department of Aeronautics and Astronautics at Stanford University. is primary research interest is in the areas of multi-functional materials and intelligent structures with particular emphases on structural health monitoring, self-sensing diagnostics, intelligent sensor networks, and multifunctional energy storage composites for transportation vehicles as well safety-critical assets. He is a recipient of the SHM Lifetime Achievement Award (2004), SPIE NDE Lifetime Achievement Award (2010), and the PHM lifetime Achievement Award Structural Health Monitoring. He is also a Fellow of AIAA and ASME.