Synthesis Buy Liquid Method And Modification Of Lithium Titanate Anode Material For Lithium Ion Battery

During the lithium insertion and deinsertion processes, spinel Li₄Ti₅O₁₂ hasa small volume change rate of less than 1%, which makes the material has goodcycle stability and guarantees a long life. In addition, Li₄Ti₅O₁₂ shows a highenergy utilization, stable platform, high security, etc, thus it is considered to bean excellent electrode materials for lithium-ion battery, and an ideal alternativeto carbon anode materials. Despite of this, the poor electronic conductive ofspinel Li₄Ti₅O₁₂ hinders its commercial application. In this paper, in order toincrease the conductivity of lithium titanate to improve its electrochemicalperformance, some measures were introduced, such as optimizing the synthesisprocess, modifying the surface of the materials and combining with other anodematerials. Then TG-DTA, XRD, SEM, TEM, CV, EIS, charge-discharge test etc.are employed to investigate the structure/morphology and electrochemicalproperties of target products.Lithium titanate was synthesized by liquid method and lithium hydroxidewas used as raw materials. During the synthesis process, the value of n(Li)/n(Ti),the calcination temperature and calcination time were investigated. Theexperiment results show that when the molar ratio of Li/Ti is 0.85 and thelithium titanate was heat-treated at 750℃for 8 h, we can get the target productwhich shows the best electrochemical performances. The prepared productowned a reversible capacity of 150 mAh/g.Since the lithium titanate is poor conductive materials, so we selectedactivated carbon, carbon black and polyvinyl alcohol (PVA) as the carbon sourceto synthesize the Li₄Ti₅O₁₂/C composite. Comparative results showed that PVAwas the best one, and the addition of PVA with a amount of 5% and 10% whouldsignificantly improved the cycle stability and rate performance of Li₄Ti₅O₁₂.When charged at 5 C, both of the samples could maintain a reversible capacity ofabout 123 mAh/g and 125 mAh/g after 60 cycles.Selecting lithium titanate as the base material,the composite electrodematerials of Li₄Ti₅O₁₂/TiO₂, Li₄Ti₅O₁₂/CuO and Li₄Ti₅O₁₂/Fe2O3 weresynthesized and their electrochemical properties were studied. Researchesindicated that the combination of lithium titanate and titanium dioxide was agood choice. When the concentration of titanium dioxide was 10%, the batteryfabricated using Li₄Ti₅O₁₂/TiO₂ displayed a high reversible capacity. Charged at0.5 / 1 /2 / 5 C, its discharge capacity was 168 / 163 / 155 / 139 mAh/g,respectively. In addition, the composite with a concentration of titanium dioxide at 5% possessed a smaller charge transfer resistance, which meant the excellentelectrochemical performance at high current density. Furthermore, at differentrates, the coulomb efficiencies held almost always 100%.