SnO ₂ Nanospheres Dispersed in the Framework of Activated Carbon and Graphene as a High Performance Anode Material for Lithium-Ion Batteries

Among known electrochemical batteries, Lithium-ion batteries are best suited for portable electronics and electric vehicles because of their highest gravimetric and volumetric energy density. The anode materials used so far in commercial lithium-ion batteries are still graphite, but its specific capacity has been unable to meet the market demand. SnO₂ is a promising alternative due to its high specific capacity with 782 mAh/g, but there are many bottlenecks when it is used as anode material solely, such as poor electrical conductivity, high volume change rate. In order to suppress these deficiencies, porous nano-sized SnO₂/graphene/activated carbon (CAC/GN/SnO₂) composites with high electrochemical performance are prepared via hydrothermal method followed by a facile calcination. The microstructures and morphology as well as electrochemical performance of the CAC/GN/SnO₂ composites were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and relevant electrochemical characterization. The results show that the SnO₂ nanospheres with a diameter of 5.68 nm are embedded in the framework of graphene and activated carbon, the mass ratios of SnO₂ to carbon have a significant effect on the properties of the composites. The sample with about 60% SnO₂ exhibiting a stable capacity of 875.2 mAh/g even after 100 cycles at a current density of 200 mA/g. After 60 cycles at different specific currents from 200 to 2000 mA/g, the reversible specific capacity was still maintained at 804.3 mAh/g at the current of 200 mA/g. Therefore, the CAC/GN/SnO₂ composites can be a desirable alternative anode material for lithium ion batteries.