High-density spherical Li4Ti5O12/C anode material with good rate capability for lithium ion batteries

Li4Ti5O12 is a very promising anode material for lithium secondary batteries. To improve the material's rate capability and pile density is considered as the important researching direction. One effective way is to prepare powders composed of spherical particles containing carbon black, A novel technique has been developed to prepare spherical Li4Ti5O12/C composite. The spherical precursor containing carbon black is prepared via an "outer gel" method, using TiOCl2, C and NH3 as the raw material. Spherical Li4Ti5O12/C powders are synthesized by sintering the mixture of spherical precursor and Li2CO3 in N-2. The investigation of TG/DSC, SEM, XRD, Brunauer-Emmett-Teller (BET) testing, laser particle size analysis, tap-density testing and the determination of the electrochemical properties show that the Li4Ti5O12/C composite prepared by this method are spherical, has high tap-density and excellent rate capability. It is observed that the tap-density of spherical Li4Ti5O12/C powders (the mass content of C is 4.8%) is as high as 1.71 g cm(-3), which is remarkably higher than the non-spherical Li4Ti5O12. Between 1.0 and 3.0 V versus Li, the initial discharge specific capacity of the sample is as high as 144.2 mAh g(-1), which is still 128.8 mAh g(-1) after 50 cycles at a current density of 1.6 mA cm(-2). (c) 2007 Elsevier B.V. All rights reserved.