Electrospun Hierarchical Li4Ti4.95Nb0.05O12/Carbon Composite Nanofibers for High Rate Lithium Ion Batteries

One-dimensional (1D) Li4Ti5O12/C and Li4Ti4.95Nb0.05O12/C composite nanofibers with diameter of approximately 200 nm and length up to several micrometers were synthesized by using electrospinning method combined with thermal treatment in argon. Field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis were performed to characterize their morphologies and structures. The results revealed that the Li4Ti4.95Nb0.05O12/C nanofibers consisted of many nano-sized particles with the diameter of 30 similar to 40 nm. Both the transition of a certain amount of Ti4+ to Ti3+ as charge compensation with the doping of niobium, uniform carbon coating on the surface and throughout the interior of each secondary nanoparticles, give rise to excellent electronic conductivity for Li4Ti4.95Nb0.05O12/C and hence greatly improve its rate capability. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.066204jes] All rights reserved.