Electrostatic Interactions Dominate the Surface Assembly of Silicon‐Based Nanospheres on Carbon Nanofibers for Flexible Lithium‐Ion Batteries

Abstract The construction of flexible freestanding silicon‐based electrodes eliminates the addition of inactive materials, improving the overall energy density, and effectively avoiding the disadvantage of active materials being easily separated from the collector due to the volume effect. However, many reports of flexible freestanding electrodes lack long‐term cycling stability. Here, 3 different silicon‐based freestanding electrodes are designed and find that the freestanding electrode with surface assembly dominated by electrostatic interactions can significantly improve long‐term cycling stability. Owing to better mechanical properties, this surface‐assembled electrode demonstrates unique flexibility. The conductive framework and unique void structure not only reveal the excellent lithium‐ion diffusion capability and charge‐transfer kinetics but also provide ample space for the volume expansion of the silicon‐based material, which endows electrodes with excellent electrochemical performance. With 2 folds, the capacity remains at 471 mA h g⁻¹ after 1000 cycles (0.5 A g⁻¹). In addition, the as‐prepared flexible pouch cell maintains high capacity and cycling stability after folding, with an average capacity degradation of only 0.01% per cycle during 1000 cycles, highlighting its considerable potential in the development of flexible devices. Remarkably, such interfacial assembly on the fiber surface also enables the modulation of multilayer assembly.