Designed synthesis of graphene-TiO2-SnO2 ternary nanocomposites as lithium-ion anode materials

Well-designed graphene-TiO2-SnO2 ternary nanocomposites, in which the nanometer-sized TiO2 and SnO2 nanoparticles formed in situ uniformly anchored on the surface of reduced graphene oxide sheets, are synthesized by a solvothermal method combined with a hydrothermal two-step method. Although the contribution of anatase TiO2 to the total specific capacity of obtained ternary nanocomposites is limited by its low theoretical specific capacity, the small amount of TiO2 nanoparticles can form more clearance space to accommodate the electrode volume change and act as stable barriers to effectively prevent the agglomeration of SnO2 nanoparticles during the charge-discharge process. Additionally, the good combination and synergistic effects among uniformly distributed TiO2 nanoparticles, high-capacity SnO2 and conductive graphene sheets work together to tackle the aggregation of nanoparticles while keeping the overall electrode sturdy and highly active in the lithium storage process. Therefore, when evaluated as anode materials in lithium-ion batteries, the as-synthesized ternary nanocomposites deliver improved cycling performance (537 mA h g(-1) at 50 mA g(-1) accompanied by coulombic efficiency of 97% after 50 cycles) and good reversible capacities (250 mA h g(-1) even at the current density 1000 mA g(-1)) in the voltage range of 0.01 to 3.00 V. By limiting the voltage window in the range of 0.01 to 1.00 V, which is the optimum voltage range for the alloying-dealloying reaction between lithium and Sn, ternary nanocomposites exhibit a more stable cycling performance (more than 70% of initial reversible capacity being retained).