微波合成锂离子电池正极材料LiCoO2的研究

为了研究锂离子电池的正极材料LiCoO2的新型制备方法,考查了反应原料配比、微波输出功率、微波合成温度和微波加热时间对LiCoO2结构和性能的影响.以LiOH·H2O和Co2O3为反应原料的最佳合成条件:Li/Co摩尔比为1.05∶1,微波输出功率为360W,反应时间为14min,合成温度为800℃.所合成LiCoO2样品均采用XRD和SEM进行表征,结果表明,采用微波合成的LiCoO2样品为单一相层状结构且晶体结构发育良好;样品的充放电循环性能良好,首次循环放电容量为130mAh/g.     

新型锂离子电池正极材料LiFePO4

橄榄石结构的LiFePO4工作电压3.4V,理论容量170mAh/g,充放电结构稳定,循环性能好,成本低,安全无毒,成为当前研究的热点.本文在介绍该材料的结构与性能的关系、充放电机理基础上,综述了近年来对该材料的研究进展,并提出了进一步发展的方向.     

锂离子电池负极材料的制备及应用进展

锂离子电池作为最具开发应用前景的新型储能材料,不仅具有安全、高效、对环境无污染的优点,而且具备相对质量轻、工作电压高、能量密度大、循环寿命长等一系列优势,已成为新型能源领域的研究热点。综述了锂离子电池负极材料中碳基负极材料、硅基负极材料、锡基负极材料和金属锂负极材料的合成、性质,以及在材料的结构设计、制备工艺等方面的研究进展。     

氢化TiO2包覆核壳C/Fe3O4@rGO锂离子电池阳极材料

通过一种简便的方法制备氧空位缺陷的氢化TiO₂包覆核壳结构C/Fe₃O₄@rGO(H-TiO₂/C/Fe₃O₄@rGO)复合材料，作为锂离子电池(lithium-ion batteris, LIBs)高性能阳极材料。TiO₂在Li⁺脱嵌过程中体积膨胀系数约为4%,可缓解Fe₃O₄在充放电过程中的体积膨胀，提高阳极材料结构的稳定性。同时，通过氢化处理改善TiO₂较低的电导率(约1×10^-12 S·m^-1)。H-TiO₂/C/Fe₃O₄@rGO在0.3 A·g^-1的电流密度下循环200周次后比容量为867 mAh·g^-1,在1 A·g^-1的电流密度下循环700周次的比容量为505...     

用于锂离子电池的Fe3O4/C纳米结构的可控制备（英文）

采用溶剂热反应并经在氮气中煅烧的方法制备出不同形貌的Fe3O4/C纳米复合物。无需表面活性剂或模板剂,仅通过调控反应物的浓度,合成出花状、纳米片状、空心球形结构3种纳米结构,并对不同形貌的形成机理进行探讨。此外,三种不同形貌样品的电化学结果表明,花状样品的电化学综合性能显著优于另外两种形貌,在5 C的充放电电流下,其可逆比容量能达到227mAh/g,而空心球形、纳米片状结构样品的容量则分别为45、10mAh/g。     

碳包覆空心Fe3O4纳米粒子作为锂离子电池负极材料的电化学性能研究

以二茂铁为铁源,石油渣油为碳源,通过加压热解和空气氧化制备了碳包覆空心Fe3O4纳米粒子。采用X射线衍射(XRD)、透射电镜(TEM)以及高倍透射电镜(HRTEM)等测试方法对样品的形貌和结构进行表征。采用恒流充放电和交流阻抗方法测试碳包覆空心Fe3O4纳米粒子作为锂离子电池负极材料的电化学性能。在电流密度为0.2mA/cm2时,首次放电比容量高达1294.7mAh/g,30次循环之后其放电比容量为392.1mAh/g;电流密度为1mA/cm2时,首次放电比容量为216.3mAh/g,30次循环之后其放电比容量为113mAh/g。     

锂离子电池正极材料LiMnBO3的研究现状

简要概括了硼酸盐类正极材料LiMBO3的国内外研究现状。对LiMnBO3的结构、性能、改性及合成方法以及LiMnBO3在上述各方面存在的不足进行了归纳总结。     

锂离子电池正极材料LiNi0.5Mn1.5O4的制备及性能研究

以Li(CH3COO).2H2O、Ni(CH3COO)2.4H2O、Mn(CH3COO)2.4H2O和H2C2O4.2H2O为原料,聚乙二醇20000为分散剂,采用化学合成法制备了具有立方尖晶石结构的锂离子电池正极材料LiNi0.5Mn1.5O4。通过XRD、SEM和充放电测试对样品进行表征。850℃下焙烧制备的LiNi0.5Mn1.5O4样品电化学性能最佳,在3.5～4.9V电压范围内以0.2、0.5、1、2和5C充放电,其首次放电比容量分别为132.9、117.3、111.2、104.8和91mAh/g,20次循环后容量保持率分别为93.2%、98.9%、97.4%、97.3%和95.5%。     

锂离子电池正极材料LiV3O8的低温合成研究

以LiNO3和NH4VO3的原料，通过溶胶－凝胶法制备了层状锂钒氧化物LiV3O8锂离子电池正极材料，通过TG－DTG、XRD等考察了合成条件对产物首次放电比容量的影响，实验结果表明，在450℃左右热分解20h可能得到单一相产物LiV3O8，其层状结构较为完整，电化学性能好，首次放电比容量可达350mAh.g^-1，作为高能锂离子电池正极材料较为理想。     

钛酸锂——新型锂离子电池负极材料

近20年来,随着交通、通讯和信息产业的迅猛发展,电动汽车、电脑、移动通讯工具等产品对发展新型化学电源提出了更高且十分迫切的要求。在新的发展需求下应运而生的锂离子二次电池,具有能量密度和功率密度高、工作电压高、自放电率低、无记忆效应、循环寿命长、无污染等独特优势,迅速发展     

Stabilizing Co3O4 nanorods/N-doped graphene as advanced anode for lithium-ion batteries

Tricobalt tetroxide (Co₃O₄) is one of the promising anodes for lithium-ion batteries (LIBs) due to its high theoretical capacity. However, the poor electrical conductivity and the rapid capacity decay hamper its practical application. In this work, we design and fabricate a hierarchical Co₃O₄ nanorods/N-doped graphene (Co₃O₄/NG) material by a facile hydrothermal method. The nitrogen-doped graphene layers could buffer the volume change of Co₃O₄ nanorods during the delithium/lithium process, increase the electrical conductivity, and profit the diffusion of ions. As an anode, the Co₃O₄/NG material reveals high specific capacities of 1873.8 mA·h·g⁻¹ after 120 cycles at 0.1 A·g⁻¹ as well as 1299.5 mA·h·g⁻¹ after 400 cycles at 0.5 A·g⁻¹. Such superior electrochemical performances indicate that this work may provide an effective method for the design and synthesis of other metal oxide/N-doped graphene electrode materials.     

Controllable synthesis and magnetic properties of Fe3O4 and Fe3O4@SiO2 microspheres

We present a systematic study on the preparation, microstructure, and magnetic properties of Fe₃O₄ microspheres and Fe₃O₄@SiO₂ microspheres. Results showed that Fe₃O₄ microspheres’ diameter can be tuned by Fe³⁺ concentration, whereas their average grain size can be tuned by polyethylene glycol (PEG) 2000 dosage or PEG molecular weight. The magnetic saturation value of Fe₃O₄ microspheres was observed to be dependent on their average grain size, but not the sphere diameter. Fe₃O₄@SiO₂ microspheres with different magnetic saturation values were achieved by adjusting shell thickness. Furthermore, the synthesized Fe₃O₄ and Fe₃O₄@SiO₂ microspheres with high and controllable magnetic saturation value endow them with great application potentials.     

One-step gas-phase construction of carbon-coated Fe3O4 nanoparticle/carbon nanotube composite with enhanced electrochemical energy storage

Carbon nanotubes (CNTs) as superior support materials for functional nanoparticles (NPs) have been widely demonstrated. Nevertheless, the homogeneous loading of these NPs is still frustrated due to the inert surface of CNTs. In this work, a facile gas-phase pyrolysis strategy that the mixture of ferrocene and CNTs are confined in an isolated reactor with rising temperature is developed to fabricate a carbon-coated Fe₃O₄ nanoparticle/carbon nanotube (Fe₃O₄@C/CNT) composite. It is found the ultra-small Fe₃O₄ NPs (<10 nm) enclosed in a thin carbon layer are uniformly anchored on the surface of CNTs. These structural benefits result in the excellent lithium-ion storage performances of the Fe₃O₄@C/CNT composite. It delivers a stable reversible capacity of 861 mA·h·g⁻¹ at the current density of 100 mA·g⁻¹ after 100 cycles. The capacity retention reaches as high as 54.5% even at 6000 mA·g⁻¹. The kinetic analysis indicates that the featured structural modification improves the surface condition of the CNT matrix, and contributes to greatly decreased interface impendence and faster charge transfer. In addition, the post-morphology observation of the tested sample further confirms the robustness of the Fe₃O₄@C/CNT configuration.     

Fe3O4/MnO2磁性复合氧化物催化剂的制备及性能

具有磁性的非均相催化剂价格低廉、低污染、高能效、容易从溶液中分离出来。经过水热合成法合成的Fe₃O₄/MnO₂磁性复合氧化物催化剂在活化过一硫酸盐（2KHSO₅·KHSO₄·K₂SO₄）产生硫酸根自由基（SO₄-）降解水中有机污染物表现出了优良的性能。把不同质量的磁性Fe₃O₄微球与线状的MnO₂负载到一起,合成三种Fe₃O₄:MnO₂质量比分别为1:3、2:3、1:1的Fe₃O₄/MnO₂催化剂,经过XRD、SEM和TEM表征,表明这两种金属氧化物负载到一起。对比不同Fe₃O₄:MnO₂质量比的Fe₃O₄/MnO₂磁性复合氧化物催化剂活化2KHSO₅·KHSO₄·K₂SO₄的活性,发现Fe₃O₄/MnO₂（2:3）催化剂催化活性最高。通过考察不同因素对Fe₃O₄/MnO₂（2:3）催化活性的影响得出,水中罗丹明B（Rh B）降解的最佳条件为10 mg/L Rh B、0.4 g/L Fe₃O₄/MnO₂催化剂、0.3 g/L 2KHSO₅·KHSO₄·K₂SO₄、pH=8。Fe₃O₄/MnO₂（2:3）磁性复合氧化物催化剂经过3次循环利用后,催化活性没有明显下降。SO₄-在降解水中Rh B起主要作用。      

Li3SbO4: A new high rate anode material for lithium-ion batteries

Electrochemical properties of Li₃SbO₄ have been investigated as an anode in lithium-ion coin cells. X-ray powder diffraction of the material, synthesized by the conventional solid state technique with thermal treatment at 800 °C in air, confirmed a monoclinic structure with lattice parameters of a = 5.159 Å, b = 6.048 Å, c = 5.144 Å and β = 109°. Electrochemical measurements in 2032 type coin cells show that Li insertion and extraction in this material take place at 0.72 and 1.05 V vs Li/Li⁺ respectively. Although the material shows a low average reversible capacity of 81 mAhg⁻¹ at a current density of 0.05 mAcm⁻² (C/5), an excellent rate performance with nearly 100% Coulombic efficiency has been observed. Continuous cycling up to 200 cycles at current densities of 0.05, 4.0 and 8.0 mAcm⁻² shows that by increasing the current rate from C/5 to 43 C i.e. 215 times, the average reversible capacity decreases only 10%. Thus, the material might be very useful for applications requiring high rate of charge and discharge.     

One-step synthesis of Fe-phthalocyanine/Fe3O4 hybrid microspheres

Fe-phthalocyanine/Fe₃O₄ hybrid microspheres were synthesized from bis-phthalonitrile and FeCl₃·6H₂O through a simple and effective solvent-thermal route. The hybrids were monodispersed solid microspheres with diameter of ~ 400 nm. The ferromagnetic signature emerged with the saturated magnetization of ~ 55.7 emu g⁻¹, and the coercive force of ~ 93.7 Oe at 300 k. The addition of bis-phthalonitrile oligomer brought Fe₃O₄ nanoparticles novel dielectric property: a new dielectric loss peak appeared at ~ 8 GHz. Considering the microwave magnetic loss properties, two microwave magnetic loss peaks were presented at ~ 1.5 GHz and ~ 10 GHz, the former peak was attributed to the natural properties of the Fe₃O₄, and the latter originated from the interface effects between the bis-phthalonitrile oligomer and Fe₃O₄.     

以Fe2O3为原料通过水热–高温煅烧法合成LiFePO4/C纳米复合材料及其电化学性能研究（英文）

采用三氧化二铁(Fe2O3)为铁源,抗坏血酸作碳源,通过在200℃下水热反应并经煅烧后合成出LiFePO4/C纳米复合材料.抗坏血酸在水热反应体系中不但作为最终反应产物的碳源,而且还起到了限制LiFePO4颗粒生长的作用.抗坏血酸的用量对产物的形貌、结构、碳含量有重要影响,进而影响产物的电化学性能.当抗坏血酸用量为1 g时,制得的LiFePO4/C纳米复合材料的粒径在220～280 nm.该材料用作锂离子电池的正极材料时,在0.1C的电流密度下循环500次后其放电容量仍保持159 mAh/g,并且具有较好的倍率性能.     

Hydrothermal synthesis of Fe3O4 nanoparticles and its application in lithium ion battery

Well dispersed Fe₃O₄ nanoparticles with a mean diameter of about 160 nm were synthesized by a simple hydrothermal method in the presence of sodium sulfate. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectrum, and Fourier transform infrared spectra (FTIR). Electrochemical properties of the nanostructured Fe₃O₄ as cathode electrodes of lithium ion battery were studied by conventional charge/discharge tests, showing a high initial discharge capacity of 1267 mA h g^− 1 at a current density of 0.1 mA cm^− 2.     

Fe3O4 on ZnO: A spectroscopic study of film and interface properties

Magnetite (Fe₃O₄) thin films have been grown epitaxially on zinc oxide (ZnO) substrates, using reactive molecular beam epitaxy. The film quality was found to be strongly dependent on the oxygen partial pressure during growth. For a uniform Fe₃O₄ film a certain pressure variation was needed during growth. Structural, electronic, and magnetic properties were analyzed utilizing low energy electron diffraction, Hard X-ray Photoelectron Spectroscopy (HAXPES), Magneto-Optical Kerr Effect (MOKE), and X-ray Magnetic Circular Dichroism (XMCD). Diffraction patterns show clear indication for growth of Fe₃O₄ in the [111] direction on ZnO(0001). Non-destructive depth profiling by HAXPES revealed uniform magnetite thin films. Both, MOKE and XMCD measurements show easy in-plane magnetization. The dichroic spectra clearly support the formation of Fe₃O₄.     

Fe/Fe_(3)C/Fe_(3)O_(4)@C磁性微球的制备及吸波性能研究EI北大核心CSCD

薄、轻、宽、强是人们对高效电磁波吸收材料的追求。用食品级柠檬酸铁与蔗糖经过水热反应,高温煅烧制备Fe/Fe_(3)C/Fe_(3)O_(4)@C磁性微球,并通过改变柠檬酸铁与蔗糖的摩尔比,探究柠檬酸铁的含量对复合材料吸波性能的影响,有效地调控电磁参数,从而优化阻抗匹配。实验结果表明,当柠檬酸铁与蔗糖的摩尔比为5∶3时,具有较好的吸波性能:当厚度为2.5 mm时,最小反射损耗为-50.17 dB,小于-10 dB的有效吸收频宽为3.52 GHz,优异的电磁波吸收性能主要得益于微球丰富的界面、孔状结构和Fe/Fe_(3)C/Fe_(3)O_(4)磁学性能的协同作用。