Synergistically Enhance the Mechanical and Electrochemical Properties of Fiber Batteries by Designing Aramid Fiber Skeletons

ABSTRACT The practical applications of fiber lithium‐ion batteries (FLIBs) remain constrained by the insufficient mechanical robustness in terms of modulus and tensile strength due to the use of ultrathin (200 µm) metal wire skeletons, which are incompatible with textile manufacturing processes and challenging to implement in real‐world applications. Herein, we developed a mechanically reinforced FLIBs architecture employing a metal‐foil‐wrapped aramid fiber composite skeleton to address the mechanical strength issue. The rational composite skeleton achieves an exceptional modulus of 35 GPa and a tensile strength of 800 MPa, thereby effectively resolving the long‐standing modulus mismatch issue within the FLIBs during manufacturing and continuous deformation. Meanwhile, the unique wrapped architecture not only sustains 74.31% capacity retention after 300 cycles under 40 N tensile loading but also demonstrates unprecedented bending durability attributed to the stress redistribution, maintaining 92.93% capacity retention following 10 000 dynamic bending tests. Furthermore, using a lightweight AF skeleton leads to an effective increase in the active material mass fraction to 48.1%, resulting in a substantial 36% energy density boost from 109.2 to 149.2 Wh/kg. This work provides a feasible approach to addressing the synergistic relationship between the mechanical properties and electrochemical properties of fibrous electronic devices.