Flexible Nb<sub>2</sub>O<sub>5</sub>/MoS<sub>2</sub>/Carbon Nanofiber Paper Anodes for Sodium-Ion Batteries

The\ndesign and fabrication of flexible anodes are crucial for advancing\nflexible sodium-ion batteries (SIBs). Electrospun carbon nanofiber\n(CNFs) composite electrodes are expected to be an effective solution.\nHere, by beneficial introduction of appropriate amount of Nb<sub>2</sub>O<sub>5</sub> nanoparticles into pure CNFs, the problem of brittle\nstress concentration in CNFs has been significantly mitigated, providing\ngood flexible mechanical stability. However, both Nb<sub>2</sub>O<sub>5</sub> and pure CNFs face the issue of relatively low theoretical\ncapacity, which limits their application in SIBs. In order to address\nthis issue, a cattail-like flexible fiber paper anode composed of\nNb<sub>2</sub>O<sub>5</sub>/MoS<sub>2</sub>/C CNFs is developed and\nfabricated in this study. With the aid of synergetic effects, it delivers\na specific capacity of 302.68 mA h g<sup>–1</sup> at 0.1 A\ng<sup>–1</sup> higher than that of Nb<sub>2</sub>O<sub>5</sub> CNFs (156.14 mA h g<sup>–1</sup>). Additionally, it shows\nthe highest reversible specific capacity of 266.43 mA h g<sup>–1</sup> after 100 cycles at 0.1 A g<sup>–1</sup> higher than the\ncontrasted Nb<sub>2</sub>O<sub>5</sub> (154.09 mA h g<sup>–1</sup>) and MoS<sub>2</sub> (127.37 mA h g<sup>–1</sup>) anodes.\nThe relevant kinetic mechanism was revealed by analyzing the pseudocapacitive\nsodium storage behavior and theoretical calculations. This work offers\nan effective strategy for developing a high-performance flexible SIB\nanode.