Construction And Study On Nano-scale TiO₂-Graphene Electrode As Lithium Anode Material

As a prominent representative of lithium-ion battery anode material, Ti O2 has attracted significant interest due to its special features, such as high operating potential(1.3-1.8V vs.Li+/Li), small volume change(<4%) and no SEI film generation.Although it has the above advantages,the application of Ti O2 has been limited due to its fundamental flaw, such as the low theoretical capacity(335 m Ah/g), slow diffusion of ionic and low electrical conductivity. In this paper,we described a novel and simple strategy, which is based on the idea of space confinement, the synthesis of Titanium dioxide/graphene(Ti O2/G) composite materials via a water-in-oil(W/O) emulsion system or a hydrothermal method. Such composites that well-dispersed Ti O2nano-particle firmly anchored on the RGO can effectively inhibit Ti O2 aggregation and offer a direct short pathway for Li+diffusion. By designing and assembly a original electrode structure, we prepared a new electrode materials with unique micro structure.The composite materials were examined by SEM, TEM, XRD, BET, FTIR, TGA and other testing techniques. Then the electrochemical properties of the anodes were investigated by charge-discharge test, cyclic voltammetry test, ac impedance test.(1) Using a modified Hummers method, the prepared graphene oxide(GO) was used in the following experiment. To ensure uniform dispersion,we employed Ti Cl3 and highly dispersed graphene oxide solution as the raw material. A electrostatic effect was used to firmly fix(OH)-Ti+ on graphene oxide nanosheet. By One-step hydrothermal method to prepare a Ti O2/graphene nanocomposites.At a rate of 0.1 C, the capacity decreases to 119 m Ah/g after 100 cycles.(2) Graphene oxide contains pronounced hydrophilic lipophilic characteristics. It can be highly dispersed in a water/oil microemulsion. The hydrolysis reaction of Ti Cl3 was restricted in a fixed-size space,which assured the Ti O2 Nano-particle anchored firmly on the RGO. The composite that prepared by microemulsion method shows a good cycle performance and significantly rate performance. The discharge capacities of the Ti O2/RGO composite at 0.1 C, 0.5 C, 2 C, 10 C are reach to 238 m Ah/g, 207 m Ah/g,176 m Ah/g, 110 m Ah/g, respectively. The Ti O2/RGO composite shows an impressive rate cycling performance of 205 m Ah/g and 178 m Ah/g at 1 C,5 C after 100 cycles,respectively.(3) A three-dimensional Ti O2/RGO composite was prepared by microe-mulsion soft template.Early,we determined the amount of CTAB to 2.8 g/60 ml by a pre-experiment. We have successfully synthesized Ti O2/RGO tree-dimensional composite electrode. After calcination at argon atmosphere(600℃), Composite exhibits excellent electrochemical properties. At 10 C after 100 cycles, the capacity ratio can stillremain at 95 m Ah/g.