Synthesis and Characterization of Spherical La-Doped Nanocrystalline Li[sub 4]Ti[sub 5]O[sub 12]/C Compound for Lithium-Ion Batteries

A spherical -doped composite with nanocrystalline morphology and high tap density was synthesized by an "outer gel" method and a sintering process. The crystal structure, morphology, and composition of the synthesized products were investigated by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectrometry, respectively. The investigation of Brunauer, Emmett, and Teller (BET) testing, tap density testing, ac impedance analyzing, and the determination of the electrochemical properties showed that La-doped exhibited a high tap density, a large BET area, and an excellent rate capability. In contrast to , the conductivity of La-doped was obviously improved. It was observed that the tap density of spherical La-doped powders (the mass content of C is 2.9% and the mole ratio ) was as high as , and the BET area was . Between 1.0 and 3.0 V vs Li, the initial discharge capacity of the La-doped compound was as high as at the 2.0C rate. After 100 cycles, the reversible capacity was still .