Abstract:
Carbon fiber–aluminum structural battery composites have attracted widespread attention owing to their integrated structural load-bearing and battery capabilities. However, existing configurations generally rely on active coatings to provide electrochemical activity, which not only introduce additional mass but also create weak interfaces. To address these issues, this study proposes a novel intrinsic-electrode-based carbon fiber–aluminum structural battery composite configuration. It was found that the high-modulus pitch-based carbon fiber HM70, due to its unique microstructure, can serve directly as the cathode in an aluminum battery system without surface modification. Based on this finding, a carbon fiber–aluminum structural battery composite was fabricated via an integrated vacuum infusion process using HM70 carbon fiber as the intrinsic cathode, together with glass fiber fabric as the separator, aluminum mesh as the anode, and porous resin as the structural electrolyte. The results show that, when used as an intrinsic cathode, HM70 delivers a specific discharge capacity of 57.75 mAh·g
−1 at 50 mA·g
−1, with a capacity retention of 73.7% after 200 cycles, achieving approximately 84% of the aluminum-storage performance of a graphite cathode. GITT results indicate that the diffusion coefficient of AlCl
4− in HM70 carbon fiber lies in the range of 10
−8-10
−11 cm
2·s
−1, demonstrating favorable ion diffusion kinetics. The fabricated composite exhibits a specific discharge capacity of 31.7 mAh·g
−1 at 100 mA·g
−1 and maintains stable capacity output after 500 cycles. Its tensile strength, flexural strength, and flexural modulus reach 754 MPa, 237 MPa, and 93 GPa, respectively, indicating that both its mechanical and electrochemical performances are at a leading level. These results demonstrate that high-modulus pitch-based carbon fiber can serve as an intrinsic cathode in aluminum-based systems to construct structural battery composites with both excellent load-bearing capability and battery performance, providing a new strategy for the design of intrinsic-electrode-based structural battery composites.