High-density spherical Li 4Ti 5O 12/C anode material with good rate capability for lithium ion batteries

Abstract

Li 4Ti 5O 12 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 Li 4Ti 5O 12/C composite. The spherical precursor containing carbon black is prepared via an “outer gel” method, using TiOCl 2, C and NH 3 as the raw material. Spherical Li 4Ti 5O 12/C powders are synthesized by sintering the mixture of spherical precursor and Li 2CO 3 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 Li 4Ti 5O 12/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 Li 4Ti 5O 12/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 Li 4Ti 5O 12. 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.