Phosphorus-doped tin oxides/carbon nanofibers webs as lithium-ion battery anodes with enhanced reversible capacity

• P-doped SnOx/CNFs were prepared by electrospinning and thermal treatments.
• The P-SnOx/CNFs with P:Sn = 0.25:1 shows a greatly enhanced reversible capacity.
• P-doping can facilitate Li+ diffusion into SnOx/CNFs anode.
• P-doping can change the band structure of SnO2.
• The electrochemical performance of P-SnOx/CNFs depends on the amount of P-doping.

Phosphorus-doped tin oxides/carbon nanofibers (P-SnOx/CNFs) composite materials are prepared via electrospinning of a mixed solution composed of polyacrylonitrile (PAN), N,N-dimethyl formamide (DMF), tin tetrachloride, ethylene glycol and phosphoric acid as well as subsequent thermal treatments. The P-SnOx/CNFs samples with tunable P-doping contents are directly used as anodes for lithium-ion batteries without any binders and conductors, exhibiting enhanced reversible capacities and cycling stabilities in comparison with pristine undoped SnOx/CNFs (0P-SnOx/CNFs). In a controlled experiment, the 0.25P-SnOx/CNFs anode with the atomic ratio of P:Sn = 0.25:1 shows the highest specific reversible capacity of 676 mA h g−1 at 200 mA g−1 after 100 cycles. Even at a higher current density of 2000 mA g−1, it still maintains a superior specific reversible capacity of 288 mA h g−1. The improved electrochemical performances are attributed to the P-doping effects such as inducement of a stable structural protection for tin particles, and enhancement of lithium ion diffusion coefficient and electron kinetics of electrode materials.