Synthesis And Performance Of TiO₂/rGO Anode Material For Lithium Ion Battery

Lithium-ion battery have attracted many reserchers due to its high voltage and energy density,almost no self-discharge memory effect,non-pollution and so on.Compared with other batteries,such as zinc/alkaline manganese,lead,nickel chromium/hydrogen,solar energy storage batteries.In addition,lithium-ion battery is used to make electronic products lightweight.Above the all advantages of the lithium-ion battery,it has been widely used in various types of electronic products.Titanium dioxide?TiO₂?has been well investigated as anode of LIBs due to its strong redox ability,relative non-toxicity,good stability,low cost,abundance and so on.But current electrochemical property,such as cycling performance and rate capability restrict its further application.Therefore,the way how to improve the reversible rate capacity and cycling performance of titanium dioxide electrode materials attracted people's attention.In this paper,we successfully synthesized TiO₂/rGO hybrids from tetrabutyl titanate?TBT?by a one-pot hydrothermal method.The properties and mechanism of the products doping with different heteroatomic are investigated.?1?TiO₂/rGO anode material for LIBs has been synthesized by a facile direct-hydrothermal route.The morphological and structural results demonstrate that the TiO₂ nanoparticles can be homogeneously anchored on the surface of rGO.As a result,the TiO₂/rGO material exhibited a desirable discharge capacity of 142 mAh g^-11 with almost 100%capacity retention after 2000 cycling life at a current density of 0.5 A g^-1,with greatly improved rate performance at different rates of 0.1–5A g^-1,which are much superior to the TiO₂ microspheres.By analyzing the charge/discharge mechanism of lithium-ion battery,we found that the addition of GO not only restricts the growth of TiO₂ particle but also provide fast channel for Li-ions.Therefore,it will accelerate the embedding/stripping reaction process between the electrode material and the electrolyte,thus enhancing the electrochemical stability.?2?N-doped TiO₂/rGO nanoparticles were synthesized by one step hydrothermal method byusing Tetrabutyl titanate as titanium source,urea and thiourea as N source.The morphology of prepared powders has been characterized by scanning electron microscope?SEM?and transmission electron microscope?TEM?;X-ray diffractometer?XRD?was used to identify the crystal structure;X-ray diffraction fluorescence spectrometer?XPS?to study the chemical composition;Raman spectroscopy?Raman?was used to identify the structure of GO.The electrochemical performances of cells with TiO₂ and TiO₂/rGO cathodes were investigated by cyclic voltammetry?CV?,galvanostatic charge/discharge test,and electrochemicalimpedance spectroscopy,rate performance test.The N-TiO₂/rGO composite with urea as N source owns better electrochemical performances than the composite which been used thiourea as N source.It was further found that the electrochemical performance of N-TiO₂/rGO was the best when adding 0.8 g of thiourea by changing the amount of thiourea.Even under the high current density of 5 A g^-1,the sample exhibited a high discharge capacity of about 117 mAh g^-1.?3?We choose stannous chloride hydrate as the source of SnO₂,and etrabutyl titanate?Ti?OBu?₄,TBT?as the titanium source,under the temperature of 180?,finally prepared SnO₂ and TiO₂/rGO composite materials.Under the current density of 0.1 A g^-1,the composite hydrids possess a high discharge capacity of 257 mAh g^-1.The coulomb efficiency of the first charge/discharge cycle reached 86%,and the coulomb efficiency was almost reached 100%after10 laps.The results of electrochemical test showed that,with the increased addition of Sn source,the charge/discharge capacity of SnO₂ and TiO₂/rGO composites increased,but their stability decreased.We consider that in the process of lithium-ion insertion/extraction,the volume of SnO₂ microspheres varies greatly,and the dendrites of some crystals leads to the attenuation of capacity.By changing the heating time of precursor,we found that when the water heat reaction was 12 hours,the SnO₂ and TiO₂ particles were fully formed and the electrode shows the best electrochemical performance.At last,it was concluded that the composite showed the best electrochemical capability when the water thermal reaction time was 12 h and the amount of tin chloride was 0.04g.Also,the structural characterization of the synthesised sample was the best,and the electrochemical performance of the electrode was the most stable.