From properties to performance: Understanding the multifunctional performance of carbon fiber cathodes for structural batteries

Structural batteries are multifunctional rechargeable batteries that can simultaneously store electrochemical energy and carry mechanical load. The cathode component of structural batteries is usually fabricated by functionalizing lightweight carbon fibers with cathode materials and regarded as carbon fiber cathodes (CFC). With a myriad of fabrication techniques, cathode active materials and types of carbon fibers readily available, endless variation of CFC can be produced, each with differing electrochemical and mechanical properties. Here, a fundamental study to systematically relate materials’ properties to resultant multifunctional performance of CFC were probed. Intrinsic physicochemical and mechanical properties of carbon fibers were first investigated before factors affecting the multifunctional performance of CFC were determined. Through this, a high-performing CFC with specific capacity of 155 mAh g⁻¹ and stiffness of 72 GPa was developed. Correlation studies between the multifunctional properties were also assessed to provide comprehensive understanding and serve as a guide for future fabrication of CFC.