Controllable synthesis of rod-like SnO2 nanoparticles with tunable length anchored onto graphene nanosheets for improved lithium storage capability

In our work, rod-like SnO2 nanoparticles with tunable length have been successfully anchored onto graphene nanosheets through a simple and in situ hydrothermal strategy under acidic conditions. The SEM and TEM images demonstrate that the unique rod-like SnO2 nanoparticles with a diameter of 10-15 nm and length of 18-34 nm are uniformly anchored onto the surface of graphene nanosheets. Moreover, the particle sizes of rod-like SnO2 nanoparticles can be readily adjusted by simply varying the reaction temperature. Interestingly, with the increase of reaction temperature from 120 to 160 degrees C, the rod length of SnO2 nanoparticles significantly increased. More importantly, the SnO2@graphene products exhibit a very high specific surface area, which played a key role in maintaining the structural stability against the irreversible volume change during Li+ insertion/extraction. The nanocomposites show an extremely high lithium storage capability and an excellent cycling performance. The initial discharge capacities are 1284 mA h g(-1) at current densities of 200 mA g(-1). After 100 cycles, the discharge capacity still remains as high as 981 mA h g(-1), indicating a superior retention capacity.