N-doped porous hollow carbon nanofibers fabricated using electrospun polymer templates and their sodium storage properties

N-doped hollow porous carbon nanofibers (P-HCNFs) were prepared through pyrolyzation of hollowpolypyrrole (PPy) nanofibers fabricated using electrospun polycaprolactone (PCL) nanofibers as a sacrificial template. When used as anode material for NIBs, P-HCNFs exhibit a reversible capacity of 160 mA h g(-1) after 100 cycles at a current density of 0.05 A g(-1). An improved rate capability is also obtained at even higher charge-discharge rates. When cycled at a current density of 2 A g (1), the electrode can still showa reversible capacity of 80mA h g(-1). The N-doped sites, one-dimensional nanotube structure, and functionalized surface of P-HCNFs are capable of rapidly and reversibly accommodating sodium ions through surface adsorption and redox reactions. Therefore, P-HCNF is a promising anode material for next-generation NIBs.