pH effect upon sol–gel processing of titanium butoxide and lithium acetate precursors on the characteristics of Li4Ti5O12 as an anode for lithium-ion batteries

This research investigates the effect of different precursor’s pH values on the fabrication of lithium titanate (Li4Ti5O12) via sol–gel processing and its characteristics as an anode for lithium-ion batteries. The precursor solution of lithium acetate was dropped into titanium butoxide at various initial pH values of 0.14, 0.39 and 0.69. The study of synthesis of Li4Ti5O12 in the extreme acid environment is rarely investigated. Thermogravimetry-differential thermal analyzer was used to examine the thermal profile of the dried Li4Ti5O12 precursor to determine the required sintering temperature, while the crystal structure and morphology of the sintered samples were characterized using an X-ray diffractometer and scanning electron microscope. The thermal analysis shows that the precursor should be sintered at 850°C to acquire pure spinel Li4Ti5O12 crystal. An investigation of the crystal structure shows that a higher purity of Li4Ti5O12 phase with smaller crystallite is obtainable in a more acidic condition. The resultant products contain an agglomerated and irregular morphology with non-uniform size distribution. These results show that the sample with the highest purity of Li4Ti5O12 provides the best electrochemical performance, with a specific capacity of 100 mAh g−1 at 0.1 C scanning rate and fast charging characteristics up to 10 C scanning rate.