Cucumber-Shaped Construction Combining Bismuth Nanoparticles with Carbon Nanofiber Networks as a Binder-Free and Freestanding Anode for Li-Ion Batteries

Bismuth nanoparticles were synthesized in three-dimensional (3D) network carbon nanofibers by the electrospinning and carbonization method. The bionic structures with cucumber-shaped carbon nanofibers@Bi nanoparticles (CCNs@BiNs) have flexibility and a self-supporting backbone, which can directly be used as anode materials for lithium-ion batteries (LIBs). The carbon shells that wrap bismuth nanoparticles can effectively buffer the volume expansion during the lithiation process. Owing to the special structure and pseudocapacitive effect, the CCNs@BiNs electrodes can deliver a superb cycling capacity of 322 mAh g–1 at 0.25 A g–1 after 500 cycles. The rate capability with high recoverability demonstrates a capacity of 450 mAh g–1 when the current density returns to 0.1 A g–1. The binder-free and foldable CCNs@BiNs will have potential for use in energy storage devices with high demand and requirement of flexibility and long cycling.