Study on the theoretical capacity of spinel lithium titanate induced by low-potential intercalation

The view that the theoretical capacity of spinel Li₄Ti ₅O₁₂ 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 Li₄Ti₅O ₁₂, we demonstrate the corresponding reaction mechanism of the low-potential intercalation behavior of Li₄Ti₅O ₁₂ and modify the classical viewpoint on the theoretical capacity of Li₄Ti₅O₁₂. The theoretical capacity of Li ₄Ti₅O₁₂ 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.