Spinel Li4Ti5O12 as a reversible anode material down to 0 V

The electrochemical behavior of Li1.33Ti1.67O4 was investigated as an anode material discharged to 0 V using X-ray diffraction (XRD), galvanostatic cell cycling and ac impedance spectroscopy. The XRD results indicate that the lattice framework of Li1.33Ti1.67O4 is almost unchanged even after it is discharged to 0 V. The Li1.33Ti1.67O4 electrode can be cycled in the voltage range between 0 and 3.0 V with excellent cyclability and a capacity of about 200 mAh/g. During the discharge process, a 0.75 V plateau is also observed in addition to the usual 1.5 V plateau. The capacity associated with the 0.75 V plateau varies with current density and temperature. The possible cause of this low potential plateau is discussed and attributed to a carbon-triggered-capacity (CTC) effect.