Fabrication Of SnO₂-based Anode And Sulfur Cathode Materials And Their Electrochemical Lithium Storage Performances

Lithium-ion batteries（LIBs） have become the predominant energy storage system in recent years. The electrochemical performance of LIBs are mostly dependent on the lithium storage capacity of the electrode materials. As an anode material, tin dioxide（SnO₂） has attracted a wide spread attention due to its high theoretical storage capacity, whcih is two to three times more than the graphite anode material. Meanwhile, lithium sulfur batteries have been considered as one of the most promising energy storage system of high energy density of next generation., which is attributed to their high specific capacity, low cost, abundant resources and environmently friendliness. However, since the sulfur and its discharge products have poor electroconductivity, the polysulfides are easily soluble in the eletrolyte,causing the shuffle effect, which has a big impact on the practical capacity and the cycling performance. In this paper, we adopted microwave-assissted method to synthesis tin dioxide/carbon nanotube（SnO₂/CNT） hybrids as anode materials for lithium ion batteries and characterized their morphorlogy, structure and analized thier electrochemical performance. And then, we prepared sulfur/acetylene black and sulfur/graphite composite as cathod material for lithium sulfur batteries and conpared their electrochemical performances. The main works are as listed follows:1. We synthesized SnO₂/CNT composites by microwave-assissted method. This method has high efficiency, short reaction time and can be operated under atmospheric condition,which shows more advantages over traditional hydrothermal method. After 80 cycles, the reversible capacity of the material is as high as 710.4 mAh g-1, which has a big improvement compared with the pure SnO₂. The high mechanical flexibility of CNTs can act as a buffer to evade the volume expansion and contraction of SnO₂ nanosheets during Li+ insertion and extraction, which would direct to desirable cycle capability of SnO₂/carbon nanotube hybrids.2. By using ball milling method, we prepared sulfur/acetylene black and sulfur/graphite composite with different sulfur/graphite proportion. Under the condition of100 mA g-1, the first discharge capacity of the sulfur/acetylene black composite is 1173.1mAh g-1, after 100 cycles, the discharge capacity was stable around 495.0 mAh g-1, the capacity retention is 42.2%. The first discharge capacity of the sulfur/ graphite composite was 1051.2 mAh g-1, after 100 cycles, the discharge capacity is stable around 588.5 mAh g-1, the capacity retention is 56.0%, which exhibits favorable cycling stability.