Electrospun freestanding anodes for metal-ion batteries: structural design and application

With the rapid development of flexible electronic devices, flexible metal-ion batteries have attracted considerable interest. One-dimensional (1D) nanofiber materials fabricated through electrospinning are regarded as excellent candidates for flexible freestanding anodes due to their high specific surface area, short electron transport paths, and excellent flexibility. They demonstrate impressive application potential in meeting the demand for deformation and outstanding electrochemical performance. This comprehensive review delves into their structural design, such as porous, core-shell, hollow, and composite structures, with particular detail on the approaches, polymer combination, and post-treatment methods. We focus on the contribution of different structures to stability, reversible capacity, long-term cycling, and rate performance during the charge/discharge process of the freestanding nanofibrous anodes. We introduce the combination of commonly used silicon-based materials, alloys, metal oxides, and metal sulfides with multi-structure nanofibers used in anodes. The paper explains how this combination overcomes the difficulties encountered by active materials in different types of metal-ion batteries. Finally, the paper concludes and discusses the challenges and prospects of electrospinning for enhancing freestanding anode and flexible metal-ion batteries.