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1.
The pure Cr2O3 coated Li4Ti5O12 microspheres were prepared by a facile and cheap solutionbased method with basic chromium(III) nitrate solution (pH=11.9). And their Li-storage properties were investigated as anode materials for lithium rechargeable batteries. The pure Cr2O3 works as an adhesive interface to strengthen the connections between Li4Ti5O12 particles, providing more electric conduction channels, and reduce the inter-particle resistance. Moreover, LixCr2O3, formed by the lithiation of Cr2O3, can further stabilize Li7Ti5O12 with high electric conductivity on the surface of particles. While in the acid chromium solution (pH=3.2) modification, besides Cr2O3, Li2CrO4 and TiO2 phases were also found in the final product. Li2CrO4 is toxic and the presence of TiO2 is not welcome to improve the electrochemical performance of Li4Ti5O12 microspheres. The reversible capacity of 1% Cr2O3-coated sample with the basic chromium solution modification was 180 mAh/g at 0.1 C, and 134 mAh/g at 10 C. Moreover, it was even as high as 127 mAh/g at 5 C after 600 cycles. At-20℃, its reversible specific capacity was still as high as 118 mAh/g. 相似文献
2.
通过热聚合法成功制备出纳米级Li3V2(PO4)3/C正极材料,中间产物和最终材料的Li3V2(PO4)3/C颗粒均小于200 nm,无定形碳的含量为4.6%,处于Li3V2(PO4)3颗粒表面和颗粒与颗粒之间.该材料在3.0sim4.3 V和0.1 C电流下放电比容量为124 mAh/g,100次循环之后无衰减,表现出较好的循环性能.其倍率性能优异,在3.0sim4.3 V和20 C的条件下放电比容量达到80 mAh/g,在3.0sim4.8 V和10 C的条件下放电比容量达到100 mAh/g. 相似文献
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制备了Bi7Ti4NbO21,Bi4Ti3O12及Nb掺杂Bi4Ti3O12(Nb-Bi4Ti3O12)层状结构铁电陶瓷材料.结合Nb-Bi 4Ti3O12的介电温谱和 退极化实验结果,研究了Bi7Ti4NbO21的晶体结构 对其介电、压电性能的影响 .高分辨透射电镜结果表明,在Bi7Ti4NbO21中, 沿着c轴方向,(Bi2Ti3O10)2-和(BiTiNbO7)2-两个类钙钛矿层分别 与(Bi2O2)2+层叠加堆积而成.这种晶体结构决定了Bi7Ti4NbO21的 介电温谱在668℃和845℃出现介 电双峰.结合极化样品的退化实验分析,说明材料在这两个温度附近发生了铁电—铁电相变 、铁电—顺电相变,分别是(Bi2Ti3O10)2-< /sup>和(BiTiNbO7)2-层状 结构发生微观结构相变的结果.在退极化过程中,由于受热时钙钛矿层内空位引起的缺陷偶 极子的定向排列受到破坏,引起材料部分退极化,表现为300℃热处理后Bi7Ti 4NbO 21的压电活性降低了10%,显示了室温下材料的压电性能来源于自发极化的固有电 偶极子和缺陷偶极子的共同贡献. 相似文献
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用衍射仪和Guinier聚焦相机收集了含秘层状结构铁电体PbBi4Ti4O15SrBi4Ti4O15的X射线粉末衍射图谱(Cu Ka),给出了d值大1.13?的88和76条衍射线的衍射数据和指标。它们都属正交晶系,空间群Bb21m(C2v12),点阵常数和X射线理论密度为PbBi4Ti4O15α=5.431?,b=5.459?,c=41.36?; z=4;Dx=7.986g/cm3.SrBi4Ti4O15:α=5.428?,b=5.438?,c=40.94?;Z=4;Dx=7.447g/cm3. 相似文献
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本文研究了在真空、空气和氧气中烧结制备的三种 CaCu3Ti4O12陶瓷材料的介电特性. 交流阻抗测量结果表明在10—300 K温度范围, 三种样品的介电温谱中均出现三个平台, 其电阻实部和电容虚部在相应温度出现损耗峰, 真空条件烧结的样品具有较高的介电平台和较明显的电阻实部与电容虚部峰值, 表明氧含量和氧空位对CaCu3Ti4O12的介电性质具有重要影响, 介电温谱出现的三个平台分别源于晶粒、晶界及氧空位陷阱.温谱分析表明晶粒的激活能与烧结气氛有较大关系,氧空位引起的电子短程跳跃及跳跃产生的极化子是晶粒电导和电容的主要起源.氧空位陷阱的激活能基本与烧结气氛无关,约为0.46 eV. 氧空位对载流子的陷阱作用是CaCu3Ti4O12 低频高介电常数的重要起源. 相似文献
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分别采用LiOH·H2O, NH4VO3, HNO3, C2H5OH作为原料在没有PVP和有PVP存在下合成了棒状和棒束状两种相貌的γ-LiV2O5. 棒状γ-LiV2O5材料中棒的直径为500~800 nm,而棒束状的γ-LiV2O5材料则是直径为100~600 nm的棒组成的,形貌比较均匀. 同时研究了此体系中γ-LiV2O5的合成机制. 将合成的材料进行电化学测试,棒束状的γ-LiV2O5 的电化学性能更好,在电流密度为30 mA/g时的初始放电比容量为269.3 mAh/g,循环20次之后容量仍保持在228 mAh/g. 相似文献
8.
Spinel lithium titanate (Li4Ti5O12) as novel anode material for room-temperature sodium-ion battery 下载免费PDF全文
This is the first time that a novel anode material, spinel Li4Ti5O12 which is well known as a “zero-strain” anode material for lithium storage, has been introduced for sodium-ion battery. The Li4Ti5O12 shows an average Na storage voltage of about 1.0 V and a reversible capacity of about 145 mAh/g, thereby making it a promising anode for sodium-ion battery. Ex-situ X-ray diffraction (XRD) is used to investigate the structure change in the Na insertion/deinsertion process. Based on this, a possible Na storage mechanism is proposed. 相似文献
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本文通过凝胶热聚合路线合成了层状的O3相正极材料Na1-xCr1-xTixO2(x=0, 0.03, 0.05),采用X射线衍射、扫描电子显微镜来分析其晶体结构和微观形貌. 研究发现,适量的钛掺杂有助于形成更均匀的颗粒并且会改变样品的颜色. 作为钠离子电池正极材料,Na//Na0.97Cr0.97Ti0.03O2具有非常高的库伦效率(首次高于96%),并且在2.0-3.6 V的电化学窗口下,用0.2 C的倍率循环100次,只有4%的容量衰减;在32 C倍率下有110 mAh/g的比容量. 相似文献
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Significant effect of electron transfer between current collector and active material on high rate performance of Li4Ti5O12 下载免费PDF全文
The rate and cycling performances of the electrode materials are affected by many factors in a practical complicated electrode process. Learning about the limiting step in a practical electrochemical reaction is very important to effectively improve the electrochemical performances of the electrode materials. Li4Ti5O12, as a zero-strain material, has been considered as a promising anode material for long life Li-ion batteries. In this study, our results show that the Li4Ti5O12 pasted on Cu or graphite felt current collector exhibits unexpectedly higher rate performance than on Al current collector. For Li4Ti5O12, the electron transfer between current collector and active material is the critical factor that affects its rate and cycling performances. 相似文献
12.
Seo Hee Ju 《Journal of Physics and Chemistry of Solids》2009,70(1):40-67
Spherical-shaped Li4Ti5O12 anode powders with a mean size of 1.5 μm were prepared by spray pyrolysis. The precursor powders obtained by spray pyrolysis had no peaks of crystal structure of Li4Ti5O12. The powders post-treated at temperatures of 800 and 900 °C had the single phase of spinel Li4Ti5O12. The powders post-treated at a temperature of 1000 °C had main peaks of the Li4Ti5O12 phase and small impurity peaks of Li2Ti3O7. The spherical shape of the precursor powders was maintained after post-treatment at temperatures below 800 °C. The Brunauer-Emmett-Teller (BET) surface areas of the Li4Ti5O12 anode powders post-treated at temperatures of 700, 800 and 900 °C were 4.9, 1.6 and 1.5 m2/g, respectively. The initial discharge capacities of Li4Ti5O12 powders were changed from 108 to 175 mAh/g when the post-treatment temperatures were changed from 700 to 1000 °C. The maximum initial discharge capacity of the Li4Ti5O12 powders was obtained at a post-treatment temperature of 800 °C, which had good cycle properties below current densities of 0.7 C. 相似文献
13.
Y. Yu 《Solid State Communications》2005,135(8):485-489
Spinel Li4Ti5O12 thin films are important for the fabrication of rechargeable lithium microbatteries. Porous thin films of Li4Ti5O12 were prepared by electrostatic spray deposition (ESD) technique with lithium acetate and titanium butoxide as the precursors. The structures of these films were analyzed by scanning electron microscopy and X-ray diffraction. Coin-type cells with a liquid electrolyte were made with the Li4Ti5O12 films against metallic lithium. Their electrochemical performance was investigated by means of galvanostatic cell cycling, cyclic voltammetry and Ac impedance spectroscopy. It was found that pure spinel phase of Li4Ti5O12 was obtained. After annealing at the optimal temperature of 700 °C, the films can deliver a reversible specific capacity of about 150 mAh/g with excellent capacity retention after 70 cycles. Their electrochemical characteristics were quite comparable with those of the Li4Ti5O12 laminate electrodes containing carbon black additive. 相似文献
14.
采用Sol-Gel工艺低温制备了Si基Bi3.25La0.75Ti3O12铁电薄膜.研究了退火温度对薄膜微观结构、介电特性与铁电性能的影响.500℃退火处理的Bi3.25La0.75Ti3O12薄膜未能充分晶化,晶粒细小且有非晶团聚,介电与铁电性能均较差.高于550℃退火处理的Bi3.25La0.75
关键词:
铁电薄膜
3.25La0.75Ti3O12')" href="#">Bi3.25La0.75Ti3O12
Sol-Gel工艺 相似文献
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采用sol-gel工艺, 在分层快速退火的工艺条件下成功地制备了高质量Si基Bi4Ti3O12铁电薄膜. 研究了Si基Bi4Ti3O12薄膜的生长行为、铁电性能、C-V特性和疲劳特性. 研究表明: Si基Bi4Ti3O12薄膜具有随退火温度升高沿c轴择优生长的趋势; 退火温度通过影响薄膜的晶粒尺寸、生长取向和薄膜中载流子的浓度来改变Si基Bi关键词:
sol-gel法
铁电薄膜
4Ti3O12')" href="#">Bi4Ti3O12
C-V特性 相似文献
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在溶胶-凝胶工艺获得高质量Bi4Ti3O12薄膜的基础上 ,制备了Ag/Bi4Ti3O12栅n沟道铁电场效应晶体管. 研 究了Si基Bi4Ti3O12薄膜的生长特性及其对铁电薄膜/ 硅的界面状态和铁电场效应晶体管存储特性的影响. 研究表明,在合理的工艺条件下可以获 得具有较高c-轴择优取向的纯钙钛矿相Si基Bi4Ti3O12 铁电薄膜并有利于改善Bi4Ti3O12/Si之间的界面特性; 顺时针回滞的C-V特性曲线和C-T曲线表明Ag/Bi4Ti3O12栅n沟道铁电场效应晶体管具有极化存储效应和一定的极化电荷保持能力; 器件的转移(I< sub>sd-VG)特性曲线显示Ag/Bi4Ti3O12 sub>栅n沟道铁电场效应晶体管具有明显的栅极化调制效应.
关键词:
铁电场效应晶体管
4Ti3O12')" href="#">Bi4Ti3O12
存储 特性
溶胶-凝胶工艺 相似文献
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Spinel Li4Ti5O12/C powders were synthesized successfully by a simple rheological phase method using polyvinylbutyral (PVB) as both template and carbon source. The structure and morphology characteristics of the composite were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy and transmission electron microscopy. The XRD results showed that the composite had a good crystallinity. Its average particle size was about 2.1 μm with a narrow size distribution as a result of homogeneous mixing of the precursors. The in situ carbon coating produced by decomposition of PVB played an important role in improving electrical conductivity, thereby enhancing the rate capacity of Li4Ti5O12 as anode material in Li-ion batteries. The Li4Ti5O12/C composite, synthesized at 800 °C for 15 h under argon, containing 0.98 wt% of carbon, exhibited better electrochemical properties in comparison with the pristine Li4Ti5O12, which could be attributed to the enhanced electrical conductive network of the carbon coating on the particle surface. 相似文献
19.
Lithium insertion into spinel Li4Ti5O12 incorporated with rutile TiO2 was investigated in order to clarify the redox mechanism responsible for the first plateau at 1.5 V vs. Li/Li+. Spherical Li4Ti5O12 powders with an average diameter of 2-3 μm can be achieved by spray drying followed by sintering process. The Li/Ti molar ratio in the precursor is selected as the factor for preparing spinel Li4Ti5O12 powders with different concentrations of rutile TiO2. The specific capacity from the first plateau at 1.5 V contributes to the major portion in the overall capacity. The rutile TiO2 in spinel Li4Ti5O12 anodes tends to improve the specific capacity at the first plateau. This can be attributed to two possible reasons: (i) rutile TiO2 provides an additional number of sites (i.e., oxygen octahedral vacancy in rutile TiO2) for the Li insertion, and (ii) less amount of residual Li oxides results in high electronic conductivity. The Li4Ti5O12 anodes display high rate capability with low irreversible capacity, indicating good reversibility of insertion/de-insertion of Li ions. The results presented in this work show unambiguously that the presence of rutile TiO2 in spinel Li4Ti5O12 has a positive effect on the performance promotion of Li4Ti5O12 anodes. 相似文献