Research On Synthesis Of Li₄Ti₅O₁₂ For Anode Material By Spray Drying

Carbon anode materials, widely used in commercial lithium ion batteries, could result in lithium plating on the surface of anode and the decomposition of electrolyte during overcharge of lithium ion batteries because of their lower lithium-intercalation potential, and could make lithium ion batteries, especially power lithium ion batteries, unsafe, and therefore impede their applications. Due to higher lithium-intercalation potential than that of carbon and excellent cycle performance resulting from zero-strain lithium intercalation, spinel lithium titanate(LTO) has been considered as one of the promising anode materials. However, the poor conductivity of LTO degrades the high rates electrochemical performance and impedes its commercial applications. In order to improve the electrochemical performance by enhancing the conductivity of LTO, the LTO and LTO/C composite were prepared by modified synthesis methods and the electrochemical performance of the prepared-anode materials was studied in details.Nanoporous and spherical LTO anode materials were successfully synthesized through spraydrying. LTO, formed after calcining the spray-dried amorphous precursor at approximately 350 °C, and well-crystallized LTO, was obtained in a single phase at 750°C.Porous and spherical LTO particles consisting of polyhedral particles assembled from 20–35 nm grains. The sample obtained at 750°C had initial discharge capacities of 218.11 and 211.06 mA?g-1 at1 C and 2C rates, respectively. After 50 cycles, the as-prepared LTO, retained 99.90% and 99.67% of its initial discharge capacities at 1C and 2C rates, respectively.The coating modification of LTO was also studied. Sugar was chosen as carbon source. The optimal amount of carbon source was determined by comparing structure and properties. Structure, morphology and electrochemical performances of LTO/C using as Sugar carbon source were investigated in detail and the coating mechanism was studied considering the high carbon content, consumption, no pollution of Sugar. Taking Sugar as carbon resource, Before the spray mixing carbon,the initial discharge capacities of 170.62 and 153.63 mA?g-1 at1 C and 2C rates, respectively. Carbon-covering, the initial discharge capacities of 102.08 and91.63 mA?g-1 at1 C and 2C rates, respectively. Compared with the pure LTO, the doped LTO has low first discharge specific capacity, low charge-discharge efficiency, high charge transfer resistances, high capacity attenuation, pianissmo reversibility, cyclic stability and low rate capability.