Porous structured SnO₂ nanofibers and nanotubes as anode materials for sodium-ion batteries

Sodium has similar electrochemical properties compared to lithium besides its abundance on earth. Sodium-ion batteries are promising and cost-effective alternatives to lithium-ion batteries for large scale applications where weight and energy densities are of minor importance. However, poor cycling stability and lower energy density of current sodium-ion batteries hinder their practical applications. Due to its excellent sodium ion storing capability, tin dioxide (SnO₂) has emerged as a good candidate anode material for sodium-ion batteries but large volume expansions upon cycling and subsequent pulverization of the active material is a great concern. In this study, novel tin dioxide porous nanofibers and nanotubes (Sn0₂ PNFs and Sn0₂ PNTs) were synthesized by electrospinning and subsequent heat treatment of precursors containing different amounts of mineral oil. Results indicated that porous nanofibers led to higher capacity and improved cycling stability when compared to high surface area nanotubes. Electrochemical performance tests revealed that porous nature of SnO₂ PNFs and SnO₂ PNTs anodes was the cause for good electrochemical performance, including relatively high capacity (311.8 mAhg^-1 and 225 mAhg^-1), large Coulombic efficiency (93.1% and 83.62%) and good capacity retention (79.2% and 79.47%) after 25th cycle, respectively.