A simple strategy to prepare a hybrid of nanocomposites of anatase TiO2/graphene nanosheets （GNS） as anode materials for lithium-ion batteries was reported.The morphology and crystal structure were studied by X-ray ...A simple strategy to prepare a hybrid of nanocomposites of anatase TiO2/graphene nanosheets （GNS） as anode materials for lithium-ion batteries was reported.The morphology and crystal structure were studied by X-ray diffraction （XRD）,field emission scanning electron microscopy （FE-SEM） and transmission electron microscopy （TEM）.The electrochemical performance was evaluated by galvanostatic charge-lischarge tests and alternating current （AC） impedance spectroscopy.The results show that the TiO2/GNS electrode exhibit higher electrochemical performance than that of TiO2 electrode regardless of the rate.Even at 500 mA/g,the capacity of TiO2/GNS is 120.3 mAh/g,which is higher than that of TiO2 61.6 mAh/g.The high performance is attributed to the addition of graphene to improve electrical conductivity and reduce polarization.展开更多
TiO2-B was synthesized by solid-state reaction. The structures, surface morphologies and electrochemical performances of TiO2-B were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） ...TiO2-B was synthesized by solid-state reaction. The structures, surface morphologies and electrochemical performances of TiO2-B were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） and electrochemical measurement, respectively. The effects of calcining temperature, molar ratio of K2O to TiO2 and calcining time on the characteristics of TiO2-B were investigated. The results show that the calcining time exerts a significant influence on the electrochemical performances of TiO2-B. The TiO2-B is obtained with good crystal structure and suitable size by using K2Ti4O9, which is prepared at 950 ℃for 24 h under the condition of x（K2O）/x（TiO2）=1：3.5. The TiO2-B delivers all initial discharge capacity of 231.6 mA.h/g. And the rate caoacitv is 73.2 mA-h/g at 1 675 mA/g, which suggests that TiO2-B is a promising anode material for the lithium ion batteries.展开更多
通过机械混合法将Si和TiO2复合合成锂离子电池复合负极材料。采用XRD、SEM和电化学测试等手段对复合材料进行一系列表征和测试,考察了不同TiO2复合量对Si负极材料性能的影响。结果表明:复合后材料的首次库仑效率明显提高,循环性能也有...通过机械混合法将Si和TiO2复合合成锂离子电池复合负极材料。采用XRD、SEM和电化学测试等手段对复合材料进行一系列表征和测试,考察了不同TiO2复合量对Si负极材料性能的影响。结果表明:复合后材料的首次库仑效率明显提高,循环性能也有明显的改善。当Si与TiO2质量比为1∶1时,电极材料的首次放电比容量为2 099.0m Ah/g,首次库仑效率为78.7%,0.5 A/g电流密度下首次放电比容量为1 112.1 m Ah/g,循环50次后比容量保持在480.4 m Ah/g。展开更多
The crystalline structure and surface morphology of TiO2 semiconductor coating play an important role in the conversion efficiency of dye-sensitized solar cells. In order to obtain TiO2 coating with controllable morph...The crystalline structure and surface morphology of TiO2 semiconductor coating play an important role in the conversion efficiency of dye-sensitized solar cells. In order to obtain TiO2 coating with controllable morphology and high porosity, nanoporous TiO2 films were fabricated on conducting glass （FTO） substrates, Ti thin films （1.5-2 gin） were deposited on conducting glass （FTO） substrates via the DC sputtering method, and then electrochemically anodized in NH4F/ethylene glycol solution. The crystalline structure and surface morphology of the samples were characterized by X-ray diffraction （XRD） and field emission scanning electron microscopy （FESEM）, respectively. The influences of anodizing potential, electrolyte composition, and pH value on the surface morphology of nanoporous TiO2 films were extensively studied. The growth mechanism of nanoporous TiO2 films was discussed by current density variations with anodizing time. The results demonstrate that nanoporous TiO2 films with high porosity and three-dimensional （3D） networks are observed at 30 V, when the NH4F concentration in ethylene glycol solution is 0.3% （mass fraction） and the electrolyte pH value is 5.0.展开更多
基金Project(Y4110230)supported by Natural Science Foundation of Zhejiang Province,ChinaProject(51204146,51101140)supported by the National Natural Science Foundation of ChinaProject(2012M521197)supported by Postdoctoral Science Foundation of China
文摘A simple strategy to prepare a hybrid of nanocomposites of anatase TiO2/graphene nanosheets （GNS） as anode materials for lithium-ion batteries was reported.The morphology and crystal structure were studied by X-ray diffraction （XRD）,field emission scanning electron microscopy （FE-SEM） and transmission electron microscopy （TEM）.The electrochemical performance was evaluated by galvanostatic charge-lischarge tests and alternating current （AC） impedance spectroscopy.The results show that the TiO2/GNS electrode exhibit higher electrochemical performance than that of TiO2 electrode regardless of the rate.Even at 500 mA/g,the capacity of TiO2/GNS is 120.3 mAh/g,which is higher than that of TiO2 61.6 mAh/g.The high performance is attributed to the addition of graphene to improve electrical conductivity and reduce polarization.
基金Project(2007BAE12B01) supported by the National Key Technology R&D Program of China
文摘TiO2-B was synthesized by solid-state reaction. The structures, surface morphologies and electrochemical performances of TiO2-B were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） and electrochemical measurement, respectively. The effects of calcining temperature, molar ratio of K2O to TiO2 and calcining time on the characteristics of TiO2-B were investigated. The results show that the calcining time exerts a significant influence on the electrochemical performances of TiO2-B. The TiO2-B is obtained with good crystal structure and suitable size by using K2Ti4O9, which is prepared at 950 ℃for 24 h under the condition of x（K2O）/x（TiO2）=1：3.5. The TiO2-B delivers all initial discharge capacity of 231.6 mA.h/g. And the rate caoacitv is 73.2 mA-h/g at 1 675 mA/g, which suggests that TiO2-B is a promising anode material for the lithium ion batteries.
文摘通过机械混合法将Si和TiO2复合合成锂离子电池复合负极材料。采用XRD、SEM和电化学测试等手段对复合材料进行一系列表征和测试,考察了不同TiO2复合量对Si负极材料性能的影响。结果表明:复合后材料的首次库仑效率明显提高,循环性能也有明显的改善。当Si与TiO2质量比为1∶1时,电极材料的首次放电比容量为2 099.0m Ah/g,首次库仑效率为78.7%,0.5 A/g电流密度下首次放电比容量为1 112.1 m Ah/g,循环50次后比容量保持在480.4 m Ah/g。
基金Projects(21171027,50872014) supported by the National Natural Science Foundation of ChinaProject(K1001020-11)supported by the Science and Technology Key Project of Changsha City,China
文摘The crystalline structure and surface morphology of TiO2 semiconductor coating play an important role in the conversion efficiency of dye-sensitized solar cells. In order to obtain TiO2 coating with controllable morphology and high porosity, nanoporous TiO2 films were fabricated on conducting glass （FTO） substrates, Ti thin films （1.5-2 gin） were deposited on conducting glass （FTO） substrates via the DC sputtering method, and then electrochemically anodized in NH4F/ethylene glycol solution. The crystalline structure and surface morphology of the samples were characterized by X-ray diffraction （XRD） and field emission scanning electron microscopy （FESEM）, respectively. The influences of anodizing potential, electrolyte composition, and pH value on the surface morphology of nanoporous TiO2 films were extensively studied. The growth mechanism of nanoporous TiO2 films was discussed by current density variations with anodizing time. The results demonstrate that nanoporous TiO2 films with high porosity and three-dimensional （3D） networks are observed at 30 V, when the NH4F concentration in ethylene glycol solution is 0.3% （mass fraction） and the electrolyte pH value is 5.0.
