Rational construction of yolk-shell CoP/N,P co-doped mesoporous carbon nanowires as anodes for ultralong cycle life sodium-ion batteries.

Owing to the natural abundance and low-cost of sodium, sodium-ion batteries offer advantages for next-generation portable electronic devices and smart grids. However, the development of anode materials with long cycle life and high reversible capacity is still a great challenge. Herein, we report a yolk-shell structure composed of N,P co-doped carbon as the shell and CoP nanowires as the yolk (YS-CoP@NPC) for a hierarchically nanoarchitectured anode for improved sodium storage performance. Benefitting from the 1D hollow structure, the YS-CoP@NPC electrode exhibits an excellent cycling stability with a reversibly capacity of 211.5 mA h g -1 at 2 A g -1 after 1000 cycles for sodium storage. In-depth characterization by ex situ X-ray photoelectron spectroscopy and work function analysis revealed that the enhanced sodium storage property of YS-CoP@NPC might be attributed to the stable solid electrolyte interphase film, high electronic conductivity and better Na + diffusion kinetics.