Preparation And Electrochemical Performance Of Carbon Coated SnO₂ Nanospheres

SnO₂, as a n-type wide band gap semiconductor material, has excellent properties of optical, electrochemical, catalytic, and gas sensing etc., It is promising to be a potential anode materials for Li-ion batteries, due to its high theoretical capacity、rich reserves in nature etc. however, as an anode material, due to the huge volume change （over 200%） of electrode material during the process of Li-Sn alloying/dealloying, leading to pulverization、 collapse of electrode, resulted in the degradation of the cycle performance. The addition of elastic matrix-carbon material into SnO₂ nanomaterials, accelerating the transport of Li and electronic, at the same time, SnO₂ hollow structure with large specific surface area, can buffer volume change in the process of electrochemical. First, we successfully synthesized SnO₂/C nanosphere by one-pot hydrothermal method; second, we synthesized SnO₂ hollow nanosphere, then we used D-glucose as Carbon resource, synthesized the Carbon coated SnO₂ hollow nanosphere. Finally, the electrochemical performance of two nanomaterials with different method and the comparision of the result were investigated, Including:1. Synthesis and electrochemical properties of SnO₂/C naospheres.We synthesized SnO₂/C nanospheres by one-pot hydrothermal method by SnCl₂ as the source of tin and D-glucose as the source of carbon, the diameter of carbon is about 600 nm. With a series of electrochemical test, we find that a capacity of 401.55 mAh/g can be obtained after 50 cycles at a current density of 0.5C, due to the elastic feature of carbon material, buffering the volume change during the charge /discharge, promoting the cycle life.2. Preparation and electrochemical properties of carbon coated SnO₂ hollow nanospheres.First, we successfully prepared the SnO₂ hollow nanospheres through hydrothermal method; Then, Carbon coated SnO₂ hollow nanosphere was synthesized by hydrothermal-calcining, the thickness of carbon is 0-20 nm. It found that the concentration of D-glucose and time of hydrothermal play an important role in the thickness of carbon. The electrochemical tests show a very stable capacity of about 418 mAh/g after 50 cycles at a current density of 0.5C. Carbon coated SnO₂ hollow nanosphere composites promote its cycle performance.