Mesoporous Carbon-Coated Bismuth Nanorods as Anode for Potassium-Ion Batteries

A new type of a mesoporous carbon-coated bismuth (Bi@C) composite in the form of nanorods is fabricated and used as anode material in a potassiumion battery (KIB). The rod-like Bi core is composed of nanoparticles and confined by a shell of amorphous carbon. The KIB with such Bi@C anode exhibits a high storage capacity of 425 mAh g(-1) at 0.2 A g(-1). The mesoporous Bi@C, with a large surface area and an appropriate pore size is in close contact with the electrolyte and facilitates the diffusion of K thorn ions. The carbon shell soothes the mechanical stresses owing to the volumetric changes of the anode during charging and discharging of the battery, preventing the degradation of active material and delivering a cyclic stability of over 500 cycles. This superior performance demonstrates the importance of a structural design that can offer a new pathway to anode development in KIB as well as in other energy storage devices.