Free-standing N-doped hollow carbon fibers as high-performance anode for potassium ion batteries

A novel hierarchical architecture—N-doped hollow carbon fibers decorated with N-doped carbon clusters (NHCF@NCC)—was synthesized for high-performance anode material of potassium ion batteries (PIBs). The material is formulated with porous N-doped hollow carbon fibers as the backbone, which effectively shortens the diffusion length of potassium ion and increases the interface between the electrode and electrolyte. In addition, the N-doped carbon clusters attached on the hollow carbon fibers can provide abundant reactive sites. Specially, NHCF@NCC could form a freestanding electrode with a three dimensional interconnected conductive network owing to the ultrahigh aspect ratio. In this way, NHCF@NCC delivers an excellent electrochemical performance as free-standing anode materials of PIBs, exhibiting a high reversible capacity of 310 mA h g −1 at a current density of 100 mA g −1 , a long cycling stability of 1000 cycles with negligible degradation, and a superior rate performance of 153 mA h g −1 at a large current density of 2000 mA g −1 .