Highly crystalline Prussian blue anchored on electrospun carbon nanofibers as flexible electrode for high power sodium-ion batteries

Flexible electrode is an important part of wearable electronics. Herein, flexible Prussian blue@Carbon nanofibers electrode is fabricated using electrospun carbon nanofiber as electron-donating agents and carbon skeletons. Cubic-shaped Prussian blue with an edge length of 140 nm is in situ deposited on the surface of carbon nanofibers by slow co-precipitation process. The unique design not only obtains the core-shell structure, which is efficient to shorten the diffusion path of sodium ions and improve the electronic conductivity, but also effectively improves the crystallinity of Prussian blue, which is conducive to the improvement of specific capacity and cyclic life. The flexible electrode exhibits superior sodium storage properties including excellent cycling stability (89 mAh g-1 after 2000 cycles at 10C with a considerable capacity retention of 92%) and exceptional rate capability (a capacity up to 90.2 mAh g -1 even at an ultrahigh current density of 50 C). In addition, the self-supporting structure effectively improves the overall energy density of the battery. The strategy using the electron-donating properties of carbon nanofibers open new perspectives to construct other flexible electrodes.