ABSTRACT Multifunctional carbon fiber structural batteries simultaneously provide mechanical load‐bearing and energy storage capabilities, offering significant potential to replace conventional structural components, thereby enhancing the overall energy density of the system. However, achieving high multifunctional efficiency remains challenging, as lithium‐ion transport in carbon fibers is restricted at high current densities, resulting in poor rate capability and significantly decreased reversible capacity. To solve this problem, this work develops an integrated structural anode of carbon/carbon composite (C/C) for both structural support and energy storage. Atomic force microscopy combined with in situ characterization techniques, including in situ Fiber Bragg Grating sensing, in situ electrochemical impedance spectroscopy, and Operando Raman spectroscopy, reveals that the unique “onion‐skin” buffering structure in C/C significantly enhances the mechano‐electrochemical properties of the electrode through a synergistic “shielding‐channeling” mechanism. The all‐fiber structural lithium‐ion battery with commercial organic electrolyte demonstrates a high energy density of 60 Wh kg −1 with excellent power density (65 W kg −1 ) and cycling stability. Remarkably, it achieves a record‐high near‐unity multifunctional efficiency (0.96), while maintaining remarkable electrochemical stability under tensile, bending and out‐of‐plane compressive conditions, demonstrating great potential for applications in aerospace systems, intelligent transportation, and next‐generation lightweight structural energy storage technologies.
Liu et al. (2026) studied this question.