Controlled Synthesis And Lithium Storage Performance Of SnO₂/N-doped Graphene Nanocomposites

Metal oxides such as SnO₂ have been regarded as promising alternative anode materials for the next-generation lithium-ion batteries?LIBs?due to their high theoretical capacities.However,their practical applications are significantly hampered by their poor cycling stability and low rate performance resulted from their huge volume variation during charge and discharge processes.In this work,several kinds of nanocomposites based on SnO₂ and N-doped graphene?NG?have been successfully developed through various methods by combination of the lithium storage advantage of nanostructures and NG to improve the structural integrity and lithium storage performance of the electrode materials.?1?Composites consisting of SnO₂ Quantum dots and NG?SnO₂ QDs/NG?were prepared via a combination of solvothermal and calcination route using SnCl4·5H2O,GO,DMF,N2H4·H2O as the raw materials.Structural characterizations revealed that SnO₂ QDs with an average size of 4 nm were tightly anchored on the surface of N-doped graphene nanosheets.When used as the anode material for LIBs,SnO₂ QDs /NG delivered a high capacity of 1563 mAh g-1 at a current density of 100 mA g-1 over 200 cycles,and the capacity could remain at 1038 mAh g-1 at 1 A g-1 over 350 cycles and 495 mAh g-1 at 10 A g-1,respectively.?2?Composites of SnO₂ nanoparticles and NG?SnO₂ NPs/NG?were synthesized through solvothermal treatment of the mixture of SnC2O4,citric acid,GO and urea and followed by calcination.As an anode of LIBs,the SnO₂ NPs/NG composites exhibited a reversible capacity of 1238 mAh g-1 after 100 cycles at a current density of 100 mA g-1,932 mAh g-1 after 250 cycles at 1 A g-1,and 206 mAh g-1 at 8 A g-1.?3?Composites of SnO₂ nanocrystals and NG?SnO₂ NCs/NG?were prepared by freeze-drying and heating the mixture of SnCl4·5H2O,GO and urea.When used as the anode materials for LIBs,the as-prepared SnO₂ NCs/NG composites could deliver a capacity of 1145.6 mAh g-1 at 200 mA g-1 over 200 cycles,862.2 mAh g-1 at 2 A g-1 over 150 cycles and 549 mAh g-1 at 5 A g-1.