LiCoO2中锂离子固相扩散系数随循环次数的变化

The solid diffusion coefficient of lithium-ion in LiCoO₂ cathode material has been investigated by the capacity intermittent titration technique (CITT) at different voltages and at different charge/discharge cycles. By SEM, XRD and FTIR techniques, the structure of LiCoO₂ was studied before and after charge-discharge cycles, and the relationship between solid diffusion coefficient and crystal structure was further discussed. CITT results show that the value of Li⁺ solid diffusion coefficient of LiCoO₂ is about 10^-12 cm²·s^-1. During the whole charge-discharge cycles, the Li⁺ solid diffusion coefficient decreased within the voltage of 4.0～4.3 V, which is attributed to the change of the structure of LiCoO₂.     

共沉淀法制备负热膨胀性ZrW2O8粉体及其粒径控制初探

Negative thermal expansion (NTE) material ZrW₂O₈ powders were synthesized using co-precipitation route. The precursor of ZrW₂O₈ was studied by Thermogravimetric and differential scanning calorimetry (TG-DSC). The structure and morphology of the resulting powders were characterized by Powder X-ray diffraction (XRD) and Scanning electron microscopy (SEM), respectively. The results showed that the samples were single phase of α-ZrW₂O₈ with regular shape. High temperature X-ray diffraction measurement indicated that the thermal expansion coefficient of ZrW₂O₈ was -10.35 × 10^-6 K^-1 in the temperature range from room temperature to 150 ℃, -3.08 ×10^-6 K^-1 from 200 ℃ to 600 ℃ and the average value was -5.38 × 10^-6 K^-1. At the same time, polyethylene glycol (PEG) was used as dispersant to primary control the size of ZrW₂O₈.     

新型阴极材料Ba0.5Sr0.5Co0.8Fe0.2O3-σ制备与性能研究

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-σ(BSCF), a new cathode material for solid oxide fuel cell (SOFC), was synthesized by polyacrylicacid (PAA) method. The lattice structures of samples calcined at different temperatures were characte-rized by XRD. Shrinkage, porosity and pore size of the porous BSCF as a function of sintering temperature were investigated. It was found that the cubic perovskite structure could be formed after calcination at 800 ℃ for 2 h, but not well crystallized as seen from some unknown phases, and the pure cubic perovskite structure was formed after calcination at 1 150 ℃ for 2 h. The particle size of BSCF was less than 1～2 μm. The shrinkage of the porous BSCF increased with sintering temperature, but the opposite was true for the porosity. After sintering at 1 100 ℃ for 4 h, the porous BSCF was still in an appropriate structure, with porosity of 29% and electrical conductivity above 400 S·cm^-1.     

纳米SrTiO3对高铁酸盐电化学性能影响研究

Two ferrates, K₂FeO₄ and BaFeO₄, had been prepared and characterized by XRD, IR and SEM. The electrochemical tests of the samples were carried out in the voltage range of 0.8～2.0 V and current density of 0.5～3.0 mA·cm^-2. The results indicated that performance of Zn-BaFeO₄ battery was superior to that of Zn-MnO₂ and Zn-K₂FeO₄ batteries. Nanometer SrTiO₃ prepared by Sol-gel methode with different ratio was added to the BaFeO₄ cathode in order to improve the discharge performance. The discharge capacity of the BaFeO₄ cathode was increased from 224 mAh·g^-1 to 246 mAh·g^-1 by addition of 5% nanometer SrTiO₃. The reason of enhancing BaFeO₄ electrochemical performance was discussed.     

预氧化固气法合成LiNiO2的研究

LiNiO₂ was prepared by reaction of stoichiometric amounts of thoroughly-mixed LiOH·H₂O and preoxidation nanometer-scale Ni₃O₂(OH)₄ powders in O₂ at the temperature of 700℃ for 6h. The products were tested by XRD， XPS， SEM and electrochemistry methods. It was shown that product was LiNiO₂ single-phase， and the valence of nickel was +3; the average size of it was 40nm; its initial charge specific capacity is 168mAh·g^-1 and the coulomb efficiency is 90%; the second charge specific capacity is 160mAh·g^-1 and the coulomb efficiency is 96%.     

硬脂酸法制备超细K2La2Ti3O10及其酸交换性质研究

A new stearic acid method(SAM) has been used to prepare ultrafine K₂La₂Ti₃O₁₀ nanocrystalline. Each state of synthesis process was followed by the use of FT-IR analysis. The resulting materials have been characterized by means of XRD， TEM， BET surface area analysis. The acid-exchanging property of the obtained product was also studied. The experimental results showed that comparing with the product of traditional solid-state reaction， the particle size of the K₂La₂Ti₃O₁₀ synthesized by SAM is greatly reduced， BET surface area is high(more than 11.83m²·g^-1) and has different acid-exchanging properties. It can be easily exfoliated in 2mol·L^-1 HNO₃ so-lution.     

CexPr1-xO2-δ复合氧化物的XRD和Raman表征

A series of Ce_xPr_1-xO_2-δ mixed oxides were synthesized by sol-gel method and characterized by Raman and XRD techniques. When x value was changed from 1.0 to 0.5, only a cubic phase CeO₂ was observed. The samples were very well crystallized on decreasing x from 0.50 to 0.99. For Ce_xPr_1-xO_2-δ samples 465 cm^-1 and 1 150 cm^-1 Raman peaks are attributed to the Raman active F_2g mode of CeO₂. The broad peak at about 570 cm^-1 in the region of 0.3 ≤x≤ 0.99 can be linked to lattice defects resulting in oxygen vacancies. The new band at about 195 cm^-1 may be attributed to the asymmetric vibration caused by the formation of oxygen vacancies. Calcination temperatures had great effect on the peak intensity for CeO₂ but less effect on Ce_0.8Pr_0.2O_2-δ in Raman spectra. It might be due to the transformation of the colors for the mixed oxides, the insertion of Pr atom into the ceria lattice could enhance the sintering resistance and thermal stability of the mixed oxides.     

由镁、铝醇盐配合物合成纳米粒子MgAl2O4尖晶石

Mg and Al alkoxide complex was synthesized in a cell without battery separator by electrochemical dissolution of aluminum for 6 h and magnesium for 1.8 h at 45 ℃ in ethanol solution of 0.04 mol·dm^-3 (Bu₄N)Br with a current density of 100 mA·cm^-2. IR and Raman spectroscopy were used to characterize the structure of the precursor of MgAl₂O₄. The results show that the current efficiency attains 98.4% and the precursor is MgAl₂(OCH₂CH₃)₅(acac)₃. The acac^- group-containing precursor could prevent it from agglomeration. The xerogel was obtained by drying in vacuum for 24 h and hydrolysis under pH≈8.5 of the precursor, which was heated at 350 ℃ for 2 h to obtain the nano-MgAl₂O₄ powder. XRD and TEM were used to investigate the structure of nano-MgAl₂O₄. The result suggests that the xerogel with an average particle size of 10 nm and the Nano-sized Spinel MgAl₂O₄ Particle of 12 nm thus obtained are with high purity.     

H2在非晶态合金Ni40Fe40P20表面的吸附行为

With the level of B3LYP/Lanl2dz of density functional theory and advisable adsorption models designed, the adsorption properties of the most stable cluster of Ni₂Fe₂P were calculated, and four stable configurations with the adsorption of hydrogen were gained. The geometries and HOMO contributions of 3d orbital of metal atoms and energy level properties of adsorption configurations were concerned and their Infrared Spectrum were simulated and predicted. The bond lengths and bond orders and vibration frequencies concerned synthetically, the adsorption mechanisms of hydrogen molecular on amorphous alloys Ni₄₀Fe₄₀P₂₀ surfaces were discussed in the microcosmic aspect. The hydrogen molecules adsorbing on the clusters were dissociated. In the clusters′ Infrared Spectrums of hydrogen adsorption, there were the vibration peaks with the frequency less than 500 cm^-1 caused by metal atoms and other vibration peaks with the frequency more than 500 cm^-1 caused by hydrogen atoms. Compared with the energy level DOS of the clusters before and after adsorption, it was found, that the new adsorption activity sites generated after the adsorption of hydrogen, as well as easy way for metal atoms providing electrons and participating subsequence reactions were gained.     

离子层气相反应法(ILGAR)制备CuInS2薄膜的研究

CuInS₂ thin films have been prepared by ion layer gas reaction (ILGAR) using C₂H₅OH as solvent, CuCl and InCl₃ as reagents and H₂S gas as sulfuration source. The effects of cationic concentrations and numbers of cycle on the properties of CuInS₂ film were investigated. The chemical composition, crystalline structure, surface topography, deposited rate, optical and electronic properties of the films were characterized by X-ray diffractrometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), ultraviolet-visible spectrometry (UV-Vis) and Hall System. The results show that the crystalline of CuInS₂ thin films and the deposition rate have been improved with the increase of cationic concentration, while CuxS segregation phases appear with further increasing cationic concentration. The deposition rate is close to constant as cationic concentration is fixed. CuInS₂ thin film derived form lower cationic concentration is uniform, compact and good in adhesion to the substrates. The absorption coefficient of CuInS₂ thin films is larger than 10⁴ cm^-1, and the band gap E_g is in the range of 1.30～1.40 eV. The dark resisitivity of the thin film decreases from 50 to 10 Ω·cm and the carrier concentration ranges are over 10¹⁶ cm^-3.     

Mn2+浓度对钒液流电池正极液的电化学性能影响

电解液中金属离子会影响钒液流电池的电化学性能。本文采用循环伏安法和电化学阻抗谱研究了正极液中Mn2+浓度对V髨/V(Ⅳ)电对的氧化还原过程影响规律,发现Mn2+在正极液中没有发生副反应,但严重影响V髨/V(Ⅳ)的反应活性、电极反应可逆性、离子扩散与电荷转移反应等电化学性能。循环伏安测试结果表明Mn2+浓度为0.04-0.13 g.L-1时,V髨/V(Ⅳ)电对电极反应可逆性和反应活性较高,钒离子扩散系数由参照溶液中的8.89×10-7-1.098×10-6增大至1.302×10-6-1.800×10-6 cm2.s-1,提高了-60%;电化学阻抗测试结果表明Mn2+浓度为0-0.04 g.L-1时,V髨/V(Ⅳ)电对电极反应阻抗和界面阻抗均较参照溶液中的增加不明显,但当Mn2+浓度增至0.07 g.L-1时,上述阻抗值较参照溶液增大了25%-28%。基于二者结果,Mn2+对电极反应有不同程度的负面影响,但是适当的Mn2+浓度有利于钒离子的扩散。     

钴掺杂二氧化硅膜的制备、表征及氢气分离性能

采用正硅酸乙酯(TEOS)和Co(NO3)2.6H2O为前驱体通过溶胶-凝胶法制备掺钴微孔二氧化硅膜,研究钴在二氧化硅膜材料中的存在状态、膜材料孔结构以及膜材料的气体渗透和分离性能。结果表明钴元素以Si-O-Co的形式存在于SiO2骨架之中,掺杂Co 10%的微孔SiO2膜具有典型的微孔结构,其孔体积为0.119 cm3·g-1,平均孔径在0.52 nm左右且孔径主要分布在0.4～0.55 nm之间。氢气在膜材料中的输运低温下遵循Knudsen扩散机理,高于100℃时遵循活化扩散机理,300℃时膜材料的H2渗透率达到6.41×10-7 mol.m-2.s-1.Pa-1,H2/CO2分离系数达到6.61,高于Knudsen扩散的理想分离系数。     

锌掺杂提高LiNi1/3Co1/3Mn1/3O2正极材料的电化学稳定性

通过共沉淀法与固相法相结合制备了掺锌的高稳定性Li(Ni_1/3Co_1/3Mn_1/3)_1-xZn_xO₂ (x=0, 0.02, 0.05)正极材料. 循环伏安(CV)曲线表明Zn掺杂使氧化峰与还原峰的电势差减小到0.09 V, 电化学阻抗谱(EIS)曲线表明Zn掺杂使电极的阻抗从266 Ω减小到102 Ω. Li⁺嵌入扩散系数从1.20×10^-11 cm²·s^-1增大到 2.54×10^-11 cm²·s^-1. Li(Ni_1/3Co_1/3Mn_1/3)_0.98Zn_0.02O₂正极材料以0.3C充放电在较高的截止电压(4.6 V)下比其他两种材料的电化学循环性能更稳定, 其第二周的放电比容量为176.2 mAh·g^-1, 循环100周后容量几乎没衰减; 高温(55 °C)下充放电循环100周, 其放电比容量平均每周仅衰减0.20%, 远小于其他两种正极材料(LiNi_1/3Co_1/3Mn_1/3O₂平均每周衰减0.54%; Li(Ni_1/3Co_1/3Mn_1/3)_0.95Zn_0.05O₂平均每周衰减0.38%). Li(Ni_1/3Co_1/3Mn_1/3)_0.98Zn_0.02O₂正极材料以3C充放电时其放电比容量可达142 mAh·g^-1, 高于其他两种正极材料. 电化学稳定性的提高归因于Zn掺杂后减小了电极的极化和阻抗, 增大了锂离子扩散系数.     

吡虫啉电化学性能研究

应用循环伏安法研究了吡虫啉（IDP）在玻碳电极的电化学行为. 结果表明：IDP的还原反应是不可逆的,且受扩散控制,电子转移数4,扩散系数DR 2.44×10-6cm2?s-1,反应活化能Ed 9.33 kJ?mol-1.     

真空辅助法合成Fe_3(PO_4)_2·8H_2O及对LiFePO_4/C结构、形貌和电化学性能的影响(英文)

采用了一种真空辅助沉淀法制备Fe3(PO4)2·8H2O,并以此进一步合成粒径尺寸在400 nm左右LiFePO4颗粒.研究了Fe3(PO4)2·8H2O对于磷酸铁锂的形貌、结构、电化学性能的影响.X射线衍射(XRD)结果表明,真空辅助制备的Fe3(PO4)2·8H2O具有高纯度,以此制备的LiFePO4具有高结晶度和纯度.扫描电子显微镜(SEM)结果表明,真空辅助制备的Fe3(PO4)2·8H2O具有未完全发育的颗粒,以此制备的LiFePO4均匀无硬团聚.透射电子显微镜(TEM)结果显示真空辅助制备的LiFePO4包覆一层均匀的碳.真空制备的LiFePO4显示了优异的电化学性能,在1C、10C、20C倍率下的容量分别为140、113、100 mAh·g-1.真空制备的LiFePO4的循环伏安曲线显示了小的极化电压和尖锐的氧化峰.充放电平台曲线表明真空对LiFePO4高倍率性能起到重要作用.电化学阻抗谱(EIS)计算结果显示,真空和非真空制备的LiFePO4的锂离子扩散系数分别为1.42×10-13和4.22×10-14cm2·s-1,说明真空辅助能够提高LiFePO4的扩散系数.     

离子液体BMIMBF4中对甲氧基甲苯的电化学氧化

以离子液体1-丁基-3-甲基咪唑四氟硼酸盐(BMIMBF4)为电解质,采用循环伏安法(CV)、计时电流法(CP)、原位傅里叶变换红外光谱(in situ FTIRS)法等手段研究了对甲氧基甲苯(p-MT)在铂电极上的电氧化行为.实验结果表明:对甲氧基甲苯在离子液体中的电化学氧化反应是受扩散控制的四电子不可逆过程,估算了其扩散系数D=3.4×10-7cm2.s-1,主要电氧化产物为茴香醛,加入适量的水或适当提高温度有利于电氧化反应向生成相应醛的方向进行.     

SiO44-对Li3Sc2(PO4)3快离子导体的阴离子替代效果研究

Li3Sc2(PO4)3因具有有利的离子传导通道、低的电子电导率和高的稳定性而成为全固态锂离子电池用固体电解质最具竞争力的材料之一,然而这一化合物只有在245℃以上的γ相才具有快离子传导特性。人们主要采用Zr4+、Ti4+等阳离子部分取代其中的Sc3+以改善材料的室温电导率,有关该化合物PO43-阴离子替代的报道还很少。本研究试图利用机械研磨技术,通过向Li3Sc2(PO4)3原料混合物中加入适量SiO2,以期能够实现对该化合物的部分阴离子替代。研究结果表明:所制备的Li3+xSc2(PO4)3-x(SiO4)x(x=0~0.6)系列化合物在x=0.15时电导率达到最大值,σ298=9.55×10-4 S.m-1,离子传导激活能达到最小值45.06 kJ.mol-1。29Si MAS-NMR测试结果证实所加入的SiO2主要以[SiO4]四面体形式存在替代Li3Sc2(PO4)3中部分[PO4]四面体。     

Nafion基氧化还原聚合物在空气中的电荷传输性能

利用三明治电池和伏安法测试了不同制备条件的Nafion基氧化还原聚合物膜在空气中的电荷传输性能. 研究结果表明, 混合适量聚乙二醇(PEG)的Nafion基金属联吡啶配合物{Nafion[M(bpy)2+3, PEG](M=Ru, Fe)}膜的表观电荷传递扩散系数(Dct)达到10-6-10-7 cm2·s-1 , 电子或空穴迁移率(μ)达到10-4-10-5 cm2·V-1·s-1. 在导电玻璃(ITO)电极与Nafion基氧化还原聚合物膜界面引入一层导电聚苯胺(PANI)后, 降低了其接触电阻, 使氧化还原聚合物膜的Dct提高至10-5-10-6 cm2·s-1, μ提高至10-3-10-4 cm2·V-1·s-1, 且工作电流提高了近两个数量级. 该固态氧化还原聚合物膜的性能比较稳定, 在空气中放置30天后其Dct和μ降低得很少.     

有色金属冶炼废水处理二次污泥中银的硫氰酸铵浸出动力学

以硫氰酸铵作为浸银剂,从除砷提铜后的有色金属冶炼废水处理的二次污泥中提取银,研究了银的浸出过程动力学.结果表明,硫氰酸铵浸出银的过程符合收缩核动力学模型,浸出活化能Ea为14.87kJ·mol-1,扩散系数D′为2.3×10-5exp(-1 487/RT)cm0.5·mol 0.5·s-1.根据该模型可知,硫氰酸铵浸出银的决定步骤是固体膜扩散.     

尿酸在石墨烯修饰玻碳电极上的电化学行为及测定

以抗坏血酸为还原剂,采用微波水热法化学还原氧化石墨烯合成了石墨烯纳米片,制备了石墨烯修饰的玻碳电极(RGO/GCE),并采用循环伏安法、计时电量法、交流阻抗法等电化学技术研究了尿酸在该修饰电极上的电化学行为及其影响因素。结果表明,在PBS缓冲溶液中,尿酸(UA)在石墨烯修饰电极上的电极反应是一个受扩散控制的不可逆氧化过程。电极反应的转移电子数n=2,有效面积A=0.182 cm2,扩散系数D=1.51×10-6 cm2.s-1。UA的氧化峰电流与其浓度在5.0×10-6～1.5×10-4 mol/L范围内呈良好线性,r=0.995 7。利用该RGO/GCE修饰电极可以快速准确地测定UA,检出限为2.7×10-7 mol/L,加标回收率为98%～100%。