MnO_2/NiCo_2O_4的静电自组装合成及其电化学性能

通过带负电荷的MnO2纳米片与带正电荷的Co-Ni层状双氢氧化物(LDHs)纳米片的静电自组装外加后续热处理合成了异质层状结构的MnO2/NiCo2O4复合物.采用X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、拉曼光谱、原子吸收光谱(AAS)、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对其结构和形貌进行了表征.用循环伏安(CV)、恒流充放电和电化学交流阻抗技术对其电化学性能进行了测试.研究结果表明,该方法制得的异质复合物具有多孔层状堆垛结构,这种特殊的结构不仅增大了电解液离子的接触面积,而且还为其嵌入-脱出提供了有效途径.该复合物在1 A·g-1电流密度时,-0.6-0.45 V电位窗口内的比电容达482 F·g-1,优于纯组分MnO2和NiCo2O4的电容性能.     

LaF_3表面修饰LiMn_2O_4的合成方法及电化学性能的研究(英文)

通过高温固相法制得尖晶石LiMn2O4,然后在通过简单易行的无水乙醇蒸干法包覆LaF3来修饰LiMn2O4。利用XRD,SEM来表征LaF3修饰的LiMn2O4的结构和形貌特征,并通过电化学测试研究LaF3修饰LiMn2O4的高温和常温下的电化学性能,另外结合电化学阻抗谱(EIS)和循环伏安(CV)考察表面修饰的锰酸锂的循环阻抗和循环可逆性。结果显示:经LaF3修饰过的LiMn2O4仍具有尖晶石结构,并且具有良好的电学性能。其中,以3wt%的修饰效果最好,常温循环100次和高温循环50次的循环保持率分别是91%和90%;而且,EIS和CV分别表明经LaF3修饰的LiMn2O4的电荷传递阻抗明显减小,其循环可逆性也明显提高。     

改性LiMn_2O_4的高温电化学性能

采用高温固相反应法制备改性的LiMn2O4锂离子电池正极材料.利用SEM、XRD等方法表征产物的结构特性.结果表明:所得产物均具尖晶石型LiMn2O4结构,该样品经Li2CO3改性后用作锂离子电池正极,于常温和高温下的循环性能均得到明显改善.     

Al掺杂及Al_2O_3表面包覆改性尖晶石LiMn_2O_4的电化学性能

合成了含1.5（wt）%Al2O3表面包覆的LiMn2O4和不同摩尔量Al体相掺杂的LiAlxMn2-xO4（x=0.1,0.2,0.3,0.4）电极材料。利用XRD和FSEM对制备材料的物相和形貌进行表征。结果表明,表面包覆和体相掺杂没有改变尖晶石LiMn2O4的晶体结构,所有衍射峰都归属于Fd3m空间群,但其衍射峰...     

钒酸盐化合物NaV_2O_5的水热合成及电化学性质

应用水热合成法制备NaV2O5晶体,XRD、SEM、拉曼光谱和XPS分析测试及电化学表明,该材料属正交晶系,空间群为Pmmn,呈纯相的棒状结构,长度约有20μm,宽度大约200 nm.该材料的V离子均价为+4.5价.首次放电容量达到120 mAh/g,放电平台为2.0 V.经过20个循环,容量保持率98 mAh/g,表现了良好的循环性能.     

正尖晶石LiMn_2O_4电化学性能研究

采用高温固相反应合成了尖晶石LiMn2 O4 锂离子电池正极材料 ,并对其性能进行研究 .综合考察了影响材料电化学性能的主要因素 ,诸如原材料的选择、合成温度、Li/Mn比以及添加金属元素Co等 .研究了材料在高温下的电化学性能和影响因素 ,并分析了LiMn2 O4 在电解质中的溶解和引起容量衰减的原因     

锂离子电池负极复合材料Al-Co3O4的合成及其电化学性能

采用流变相反应与热处理相结合的方法合成了锂离子电池用Al-Co3O4负极复合材料;利用充放电循环试验测定了复合材料的电化学性能;利用X射线衍射仪、扫描电镜及粒度分布仪分析了复合材料的微结构,考察了Co3O4含量、热处理温度及循环电压范围对复合材料电化学性能的影响;同时探讨了Co3O4纳米微粒在复合材料充放电过程中的作用机理.结果表明,在Al-Co3O4复合材料中,铝基体表面被Co3O4纳米颗粒所包覆;不同组成的复合材料电极的充放电循环性能均优于纯铝电极.     

三维花状Fe_2(MoO_4)_3微米球的水热制备及电化学性能

以Fe Cl3·7H2O和Na2Mo O4为原料,采用水热合成法制备三维花状Fe2(Mo O4)3微米球。探讨不同合成温度对样品形貌的影响,利用XRD、SEM和EDS等分析技术对样品的结构、形貌进行了表征,对该材料的电化学性能进行了测试。结果表明:Fe2(Mo O4)3微米球是由二维纳米片自组装而成的花状结构,合成温度为160℃时,制备的样品具有良好的电化学性能,当电流密度为100 m A·g-1,首次放电比容量为1 431 m Ah·g-1;并具有较好的循环性能和倍率性能。并对160℃合成样品表现较好电化学性能的原因进行了探讨。     

花状NH4V4O10微纳米结构的水热制备及电化学嵌锂性能

通过水热法制备了花状NH4V4O10微纳米结构. 采用XRD,SEM,TEM,XPS等测试手段对样品结构、形貌和组成进行了表征. 实验结果表明,所制得的NH4V4O10花状结构是由直径约100 nm,长度为几微米的纳米带团簇而形成. 研究了反应体系中温度、时间等因素对NH4V4O10产物形貌的影响. 将制备的NH4V4O10组装成锂模拟扣式电池,考察了其电化学嵌锂性能. 研究结果显示,所制备的花状NH4V4O10具有较高的比容量（307 mAh?g-1）,有望作为锂离子电池的新型正极材料.     

Heterostructural NiCo2O4 Nanocomposites for Nonenzymatic Electrochemical Glucose Sensing

Hierarchical nanocomposites consisting of NiCo₂O₄ nanorods and NiCo₂O₄ nanoparticles through a straightforward two-step hydrothermal process was employed as a working electrode to examine the electrochemical behavior of glucose. The NiCo₂O₄@NiCo₂O₄ heterostructures was confirmed by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffractometer (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemistry analysis. Results indicated that glucose is electrochemically oxidized with improved sensitivity at the NiCo₂O₄@NiCo₂O₄ sensor, compared to NiCo₂O₄ sensors. Analytical parameters such as the optimal potential (0.45 V), linear range from 0.4 μM to 5.2 mM, limit of detection (1.1 μΜ) (S/N=3), stability and repeatability (2.7 %) demonstrate the suitability of the prepared sensor for glucose analysis. Moreover, the proposed sensor could be used for actual samples analysis in complex matrices.     

Facile Green Synthesis of NiO/NiCo2O4 Nanocomposite as an Efficient Electrochemical Platform for Determination of Dopamine

The synthesis of NiO/NiCo₂O₄ nanoparticles by an eco-friendly, fast, simple and cost-effective approach employing Urtica extract is reported in this study. The NiO/NiCo₂O₄ nanocomposite were characterized using VSM, FTIR, XRD, and SEM techniques. Moreover, to construct a modified carbon paste electrode, NiO/NiCo₂O₄ were employed and this sensor was used for dopamine (DA) detection. Using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques, the electrochemical behavior of dopamine at the NiO/NiCo₂O₄/CPE was investigated. Analysis of dopamine, with a limit of detection (LOD) equal to 0.04 μM, in the concentration range of 0.1–100.0 μM, was facilitated by NiO/NiCo₂O₄/CPE. Moreover, the satisfactory selectivity for DA determination in the presence of uric acid (UA) and ascorbic acid (AA), was obtained. The suggested new sensor displayed a good reproducibility, sensitivity, and stability for determination of DA in drug and biological samples.     

Hydrothermal Synthesis of Na0.28V2O5 Nanobelts and their Electrochemical Behavior in Lithium Batteries

A simple low temperature hydrothermal method was found to yield Na_0.28V₂O₅ nanobelts after two days at 130 °C in acidic medium (H₂SO₄) without using any surfactant. The obtained products were characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), and Raman spectroscopy. Their morphology was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Additionally, their electrochemical behavior in a lithium battery was investigated. The XRD pattern shows that the product is composed of monoclinic Na_0.28V₂O₅ nanobelts. From the FTIR spectrum, the band centered at 961 cm^–1 is assigned to V=O stretching vibration, which is sensitive to intercalation and suggests that Na⁺ ions are inserted between the vanadium oxide layers. SEM/TEM analyses reveal that the products consist of a large quantity of nanobelts which have a thickness of 60–150 nm and a length of several tens of micrometers. The electrochemical results show that the nanobelts exhibit an initial discharge specific capacity of 390 mAh · g^–1, and its stabilized capacity still remained around 200 mAh · g^–1 after the 18th cycle.     

NiCo2O4 纳米线对H2O2电还原的催化性能

以无模板生长法制备了泡沫镍载NiCo2O4纳米线正极材料, XRD和SEM表征结果表明, 所得材料为NiCo2O4纳米线, 以循环伏安法和计时电流法研究了泡沫镍载NiCo2O4纳米线对H2O2电还原的催化性能. 结果显示, 在0.4 mol/L H2O2 和 3.0 mol/L NaOH 溶液中, 当电压为-0.4 V(vs. Ag/AgCl)时, 循环伏安的电流密度达到125 mA/cm2; 当电压为-0.2, -0.3和 -0.4 V 时, 在30 min 的测试时间内, 计时电流密度几乎均为一常数, 表明以泡沫镍载NiCo2O4纳米线为催化剂电还原H2O2具有很高的活性和很好的稳定性.     

泡沫镍负载的NiCo2O4纳米线阵列电极的超级电容性能

采用无模板自然生长法制备了泡沫镍支撑的NiCo₂O₄纳米线阵列电极, 利用扫描电镜(SEM)和透射电镜(TEM)观测了纳米线的表面形貌, 利用X射线衍射(XRD)分析了纳米线的结构, 通过循环伏安、恒流充放电和交流阻抗测试了电极的超级电容性能. 结果表明: NiCo₂O₄纳米线直径约为500-1000 nm、长度约为10 μm, 垂直且密集地生长在泡沫镍骨架上. 纳米线阵列电极的放电比容量高达741 F·g^-1, 循环420次后比容量仍保持在655 F·g^-1, 电化学阻抗测试其电荷传递电阻仅为0.33 Ω, 420次循环后电荷传递电阻仅增加0.06 Ω.     

钴酸镍纳米花/活性炭纤维复合物的制备和表征及其超级电容器性能

利用简单的水热法以及后续热处理, 将钴酸镍纳米花成功生长在活性炭纤维支架上. 场发射扫描电镜(FESEM)及透射电镜(TEM)结果表明, 纳米花是由纳米针自组装而成, 而纳米针呈多孔结构. 这种三维复合多级结构非常有利于电解质离子的渗透和电子的传输. 将该多孔钴酸镍纳米花/活性炭纤维布作为工作电极, 表现出优良的电容性能. 在1 A·g^-1时, 比电容高达1626 F·g^-1; 在10 A·g^-1时, 电容保持率为65%, 具有超高的电容值和优异的倍率特性.     

纳米铁酸锌的水热合成

利用水热合成法制备纳米铁酸锌粉体，使用XRD、TEM研究了铁酸锌晶相组成、粒度大小和形貌，并对影响合成工艺的因素如反应前驱物的pH、反应温度、反应时间与产物的关系进行系统的考察研究。结果表明：前驱物的最佳pH为11－12，反应温度为448K，反应时间为360min，可制得结晶良好、纯度高、分散性好、粒度为纳米级的ZnFe2O4粉体。     

基于NiCo2O4纳米片电极的非对称混合电容器

The looming global energy crisis and ever-increasing energy demands have catalyzed the development of renewable energy storage systems. In this regard, supercapacitors (SCs) have attracted widespread attention because of their advantageous attributes such as high power density, excellent cycle stability, and environmental friendliness. However, SCs exhibit low energy density and it is important to optimize electrode materials to improve the overall performance of these devices. Among the various electrode materials available, spinel nickel cobaltate (NiCo₂O₄) is particularly interesting because of its excellent theoretical capacitance. Based on the understanding that the performances of the electrode materials strongly depend on their morphologies and structures, in this study, we successfully synthesized NiCo₂O₄ nanosheets on Ni foam via a simple hydrothermal route followed by calcination. The structures and morphologies of the as-synthesized products were characterized by X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller (BET) surface area analysis, and the results showed that they were uniformly distributed on the Ni foam support. The surface chemical states of the elements in the samples were identified by X-ray photoelectron spectroscopy. The as-synthesized NiCo₂O₄ products were then tested as cathode materials for supercapacitors in a traditional three-electrode system. The electrochemical performances of the NiCo₂O₄ electrode materials were studied and the area capacitance was found to be 1.26 C·cm^-2 at a current density of 1 mA·cm^-2. Furthermore, outstanding cycling stability with 97.6% retention of the initial discharge capacitance after 10000 cycles and excellent rate performance (67.5% capacitance retention with the current density from 1 to 14 mA·cm^-2) were achieved. It was found that the Ni foam supporting the NiCo₂O₄ nanosheets increased the conductivity of the electrode materials. However, it is worth noting that the contribution of nickel foam to the areal capacitance of the electrode materials was almost zero during the charge and discharge processes. To further investigate the practical application of the as-synthesized NiCo₂O₄ nanosheets-based electrode, a device was assembled with the as-prepared samples as the positive electrode and active carbon (AC) as the negative electrode. The assembled supercapacitor showed energy densities of 0.14 and 0.09 Wh·cm^-3 at 1.56 and 4.5 W·cm^-3, respectively. Furthermore, it was able to maintain 95% of its initial specific capacitance after 10000 cycles. The excellent electrochemical performance of the NiCo₂O₄ nanosheets could be ascribed to their unique spatial structure composed of interconnected ultrathin nanosheets, which facilitated electron transportation and ion penetration, suggesting their potential applications as electrode materials for high performance supercapacitors. The present synthetic route can be extended to other ternary transition metal oxides/sulfides for future energy storage devices and systems.     

合成条件对尖晶石LiMn_2O_4的电化学性能的影响

以Li2 CO3、LiOH、LiNO3以及电解MnO2 (EMD)作原料 ,用固相反应法合成了尖晶石LiMn2 O4 .结果表明 ,反应物种类及合成条件对LiMn2 O4 的电化学性质有很大的影响 .其中以LiNO3和EMD为合成原料制得的LiMn2 O4 性能最佳 .其制备条件分两步 :先在 2 80℃加热 6h ,使熔融的LiNO3渗入EMD微孔 ,然后在 75 0℃下焙烧合成