Study on the Theoretical Capacity of Spinel Lithium Titanate Induced by Low-Potential Intercalation

The view that the theoretical capacity of spinel Li4Ti5O12 is limited by the number of available octahedral sites to accommodate lithium ions is debated. Combining the electrochemical and XRD results with the crystal structure of Li4Ti5O12, we demonstrate the corresponding reaction mechanism of the low-potential intercalation behavior of Li4Ti5O12 and modify the classical viewpoint on the theoretical capacity of Li4Ti5O12. The theoretical capacity of Li4Ti5O12 is limited by the number of tetravalent titanium ions, but not the octahedral or tetrahedral sites to accommodate lithium ions in the voltage range of 2.5 to 0.01 V, corresponding to 293 mAhg(-1), but not 175 mAhg(-1).