Flexible Nb₂O₅/MoS₂/Carbon Nanofiber Paper Anodes for Sodium-Ion Batteries

The design and fabrication of flexible anodes are crucial for advancing flexible sodium-ion batteries (SIBs). Electrospun carbon nanofiber (CNFs) composite electrodes are expected to be an effective solution. Here, by beneficial introduction of appropriate amount of Nb2O5 nanoparticles into pure CNFs, the problem of brittle stress concentration in CNFs has been significantly mitigated, providing good flexible mechanical stability. However, both Nb2O5 and pure CNFs face the issue of relatively low theoretical capacity, which limits their application in SIBs. In order to address this issue, a cattail-like flexible fiber paper anode composed of Nb2O5/MoS2/C CNFs is developed and fabricated in this study. With the aid of synergetic effects, it delivers a specific capacity of 302.68 mA h g–1 at 0.1 A g–1 higher than that of Nb2O5 CNFs (156.14 mA h g–1). Additionally, it shows the highest reversible specific capacity of 266.43 mA h g–1 after 100 cycles at 0.1 A g–1 higher than the contrasted Nb2O5 (154.09 mA h g–1) and MoS2 (127.37 mA h g–1) anodes. The relevant kinetic mechanism was revealed by analyzing the pseudocapacitive sodium storage behavior and theoretical calculations. This work offers an effective strategy for developing a high-performance flexible SIB anode.