| 초록 |
Solid solution Li4Ti5O12-y samples were synthesized by one step solid state carbon thermal reduction reaction using Li2CO3, anatase and carbon black under nitrogen atmosphere. An underlying formation mechanism is proposed which directs us well to prepare solid solution Li4Ti5O12-y. The formation mechanism of solid solution Li4Ti5O12-y was investigated by in situ variable temperature X-Ray diffraction (VT-XRD) and thermal gravimetric analysis/differential scanning calorimetry system (TGA-DSC). Firstly, partial Ti4+ turn to Ti3+ (TiO2-TiO2-x) due to the existence of carbon black. Secondly, Li2CO3 reacts with TiO2-x (anatase) to form Li2TiO3. Thirdly, Li2TiO3 reacts with TiO2-x to form solid solution Li4Ti5O12-y, anatase starts to transform into rutile at the same time. Rutile reacts with Li2TiO3 to form Li4Ti5O12-y at higher temperature. As a result, the as-prepared material exhibits good rate capability and cycling stability with 99.3% capacity retention after 200 cycles. |
