Electrochemical Performance Of Sn_xTi_1-xO₂ Solid Solution For Lithiumion Batteries

With the approach of the environmental crisis, the creation and applications of new resources have become the subject of many scientific researches. Lithium ion batteries are the most reputable, being widely used in many electrical appliances such as handphones, laptops, digital cameras as well as handheld electronic devices. The theoretical capacity of SnO2 material reaches 781 mAh·g-1, double that of carbon. This makes it a good subject of research on its suitability as a material of the anode of a new generation of lithium ion batteries. As a reason of that, this essay will provide an in-depth research and discussion on the suitability of tin-based oxide as a material for lithium battery anodes.In this paper, SnO2 nanoparticles are synthesized through hydrothermal method. Experiments have shown that SnO2 has a high initial capacity, but declines steeply as it undergoes cycles. In 30 cycles, the capacity decreases from 891 mAh·g-1 to 314 mAh·g-1. This is because its crystalline structure experiences a volume change up to 259% during the charge/discharge cycle. This expansion and contraction easily make the microscopic tin particles clump together, direct drop of mechanismus and the breakdown of crystal structure. Meanwhile, TiO2 nano-particles show the high cycle stability, though a low capacity. Thus further doping is done to SnO2 by mixing Ti with SnO2. Ti plays a role of non-activated matrix, that can control the volume extended and enhance the cycle performance.The paper successfully synthesized nano-scaled SnxTi1-xO2 solid solution using hydrothermal method. XRD,TEM,SEM and EDX measurements are used to detect the structure and the composition of the tin-based material, which proved that SnxTi1-xO2 is a substitutional type solid solution with Ti as the substitute atom. The CV curves of pure SnO2 and SnxTi1-xO2 electrodes are very similar, suggesting that the mechanisms of lithium stored in SnO2 and SnxTi1-xO2 are almost the same. Furthermore, SnxTi1-xO2 solid solutions are heat treated at different temperatures to investigate the influence of crystalline on cycle performance.The results show that reversible capacity increases as Sn increases in SnxTi1-xO2 solid solutions (x=0.34,0.43,0.6,0.73,0.76). The reversible capacity has increased as the heat temperature gets higher, peaking at 550℃(the largest first cycle capacity around from 400 to 800mAh·g-1 as Sn added changes). The samples heated at 300℃show a good cycle performance with a high capacity. The Sn0.76Ti0.24O2 electrode exhibits a capacity of 496 mAh·g-1 after 30 cycles, while the number is around 350 to 490 mAh-g"1 for the other electrodes with less Sn added. This is significantly better than that of SnO2 anode.