Mesoporous Li₄Ti₅O₁₂/carbon nanofibers for high-rate lithium-ion batteries

Mesoporous Li₄Ti₅O₁₂/carbon nanofibers (LTO/C NFs) are prepared by a facile electrospinning method combined with soft-template self-assembly. The morphology and structure are characterized by field-emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The diameter of as-prepared LTO/C NFs is approximately 400 nm with highly crystallinity LTO nanoparticle completely embedded in carbon framework. Nitrogen adsorption-desorption isotherms and corresponding pore size distribution reveal that the mesoporous LTO/C NFs exhibite high specific surface area (212.1 m²/g^-1) and large pore volume. Compared with the regular LTO/C NFs, the mesoporous LTO/C NFs show much higher rate capability and better capacity retention. At a current rate of 5 C, the reversible capacity of the mesoporous LTO/C NFs electrode is up to 127.4 mA h g ^-1 and still remains at 122.7 mA h g^-1 after 100 cycles. The excellent electrochemical performances are closedly related to well-defined one-dimensional (1D) mesoporous nanostructure with LTO nanoparticles embedded in the carbon framework, which efficiently shortened the path length of Li ⁺ diffusion, enhanced electrolyte-active material contact area and facilitated rapid electron transfer.