Copper-doped Li sub(4)Ti sub(5)O sub(12)/carbon nanofiber composites as anode for high-performance sodium-ion batteries

Lithium titanium oxide (Li sub(4)Ti sub(5)O sub(12 )) is a promising anode material, owing to its superior safety and reliability. However, the main challenge of Li sub(4)Ti sub(5)O sub(12) is the low material conductivity which restricts its electrochemical performance. In order to use Li sub(4)Ti sub(5)O sub(12) in practical sodium-ion batteries, copper-doped Li sub(4)Ti sub(5)O sub(12) (Li sub(4-x)Cu sub(x)Ti sub(5)O sub(12), x = 0, 0.05, 0.1) nanoparticles were prepared to enhance the electronic conductivity. Copper-doped Li sub(4)Ti sub(5)O sub(12) nanoparticles were then embedded in continuous carbon nanofibers (CNFs), which gave rise to fast electron transfer along the fiber direction. After copper-doping and CNF embedding, the resultant copper-doped Li sub(4)Ti sub(5)O sub(12)/CNFs achieved excellent reversible capacity (158.1 mAh g super(-1)) at 30 mA g super(-1), high coulombic efficiency (99.87%), and good capacity retention (91%) after 150 cycles. In addition, copper-doped Li sub(4)Ti sub(5)O sub(12)/CNFs also exhibited good rate capability. It is, therefore, demonstrated that copper-doped Li sub(4)Ti sub(5)O sub(12)/CNFs are promising anode candidate.