Low‐Temperature‐Resilient and High‐Rate Polypyrrole‐Vanadium Oxide Carbon Fiber Structural Supercapacitors with Superior Mechanical‐Electrochemical Synergy

The rapid expansion of the low‐altitude economy—particularly the development of unmanned aerial vehicles (UAVs) and electric aircraft—has intensified the trade‐off between flight endurance and payload capacity. Carbon fiber structural supercapacitors (CF‐SSCs) offer a promising solution by integrating energy storage into load‐bearing components; however, the inherent chemical inertness of carbon fibers restricts device capacitance, and their low‐temperature electrochemical behavior remains largely unexplored. Here, we construct an H 2 V 3 O 8 @PPy composite electrode via in situ low‐temperature oxidative polymerization. The uniform PPy coating facilitates rapid interfacial kinetics, provides reversible pseudocapacitance, and buffers the volume expansion of the H 2 V 3 O 8 nanorods. The assembled H 2 V 3 O 8 @PPy@CF‐SSC achieves a high specific capacitance of 1082.4 mF g −1 and an energy density of 573.6 mWh kg −1 . Crucially, the device maintains 42.1% capacitance retention at −10°C, delivering an energy density of 165 mWh kg −1 surpasses the performance of most previously reported CF‐SSCs. Furthermore, the device demonstrates robust mechanical properties, featuring a tensile strength of 126.5 MPa and a tensile modulus of 6.92 GPa. This work fills the gap in low‐temperature CF‐SSC research and provides guidance for the design of high‐energy‐density structural energy‐storage devices for extreme environments.