Understanding How Carbon Fiber Structure Controls Mechano-Electrochemical Properties of Multifunctional Composites

This award supports fundamental research aimed at advancing structural composites that simultaneously provide mechanical load-bearing capability and electrical energy storage. Replacing conventional structural components with energy-storing structural composites could reduce the mass and volume devoted to separate battery packs, thereby extending the flight endurance and operational range of drones, aircraft, and spacecraft while improving the energy efficiency of electric vehicles and other transportation systems. However, their practical development is currently constrained by limited energy density and progressive loss of mechanical integrity during repeated charging and discharging. This project will investigate how changes in carbon fiber structure and interfacial behavior during manufacturing and operation influence energy storage, strength, durability, and resistance to fracture. The knowledge generated will contribute to the development of lighter, more energy-efficient, and more reliable transportation and defense systems. The project will also support education and workforce development through teacher training, research experiences for high school and undergraduate students, curriculum development, mentoring, and public engagement. Part 2: The research will establish a fundamental understanding of the design and manufacturing of energy-storing structural composites that combine mechanical load bearing with electrical energy storage. Although these multifunctional materials could reduce the system-level mass of electric vehicles, aircraft, and spacecraft, their development is limited by low energy density and poor cycling durability. The central hypothesis is that carbon-fiber expansion, fiber microstructure, and long-term interfacial chemical degradation jointly govern electrochemical and mechanical performance. The research will address three knowledge gaps: insufficient accommodation of radial fiber expansion during lithiation, limited understanding of microstructural barriers to lithium-ion transport and storage, and loss of interfacial shear strength and fracture toughness during cycling and thermal aging. The project will determine how pre-lithiation-induced expansion affects coupled electrochemical and mechanical behavior, how radial, onion-skin, and turbostratic fiber structures control ion transport and capacity retention, and how cycling-induced interfacial transformations contribute to strength loss and crack propagation. The resulting knowledge will guide the manufacturing of high-capacity, fracture-resistant structural energy-storage composites. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.