Preparation and electrochemical properties of LiMn1.95M0.05O4 （M=Cr, Ni）

The preparation process and electrochemical properties of LiMn2O4 and LiMnl.95M0.05O4 （M = Cr, Ni） were studied. The results show that the decomposition temperature range of xerogel prepared with lithium acetate and manganese acetate as raw rnaterials is large and the decomposition speed is slow. Oxygen consumed is apt to get a prompt supplement during the preparation of LiMn2O4, and carbonization of the organic matter can be reduced or avoided, which is favorable to the combination of lithium and manganese. Using lithium acetate, manganese acetate, chromium nitrate, and nickel nitrate as raw materials and adopting the citric acid complexing method, it has been found that the prepared powders have high purity, high quality stability, and even doping characters. With the increase of sintering temperature, the particle size and crystal lattice constant of LiMn1.95M0.05O4 （M = Cr, Ni） enhance. However, the purity of the product is relatively high and has no obvious change, which is advantageous to the control of the quality of LiMn1.95M0.0504 （M = Cr, Ni）. Doping with a small amount of Cr3. and Ni^2＋ can stabilize the spinel structure of LiMn2O4, suppress the Jahn-Teller effect, and improve the cycling properties but reduce the initial capacity.     

阴极保护用阳极

介绍了牺牲阳极材料中镁基、锌基、铝基阳极的化学成分和性能特点，以及多种外加电流阴极保护用阳极材料的特点。通过对石墨阳极、高硅铸铁阳极和铅银合金阳极、镀铂阳极和混合金属氧化物阳极的性能比较，认为混合金属氧化物阳极是最为理想和最有前途的辅助阳极材料。     

Q235-304L电偶对在Na2S溶液中的电偶腐蚀行为研究

用电化学法和浸泡法研究了Q235-304L电偶对在3种不同浓度的Na2S溶液中的电偶腐蚀行为,用SEM观察试样的表面形貌.结果表明:在3种溶液中Q235钢的阳极过程均为混合控制,而304L的阴阳极过程均为电化学控制;偶接后Q235钢表面阳极金属的溶解过程与阴极过程同时进行,其阳极溶解电流大于电偶电流值;电偶腐蚀效应随阴阳极面积比的增大而增大;随着S2-浓度的升高,电偶对中Q235钢的腐蚀速率减小,电偶腐蚀效应也随之降低.     

Synthesis and characterization of LiNi0.45Co0.10Mn0.45O2 cathode for lithium ion batteries

1INTRODUCTIONAdvanced rechargeable lithium ion batteriesare attractive for use in consumer electronic andelectric vehicle(EV)application because of a fa-vorable combination of voltage,energy density,cycling performance,and have been developed rap-idly worldwide during the past decade[1,2].LiCoO2has been widely used as a cathode material in com-mercial lithiumion battery because it is reasonableeasy to synthesize and shows a stable discharge ca-pacity[3].But due to its high cost and toxic…     

Preparation and characterization of biomorphic SiC hollow fibers from wood by chemical vapor infiltration

Biomorphic SiC hollow fibers were prepared by the reactive infiltration of SiO vapor into basswood-derived charcoal. Gaseous SiO was produced from a SiO₂/Si powder mixture in Ar at elevated temperatures. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform-infrared spectroscopy were employed to characterize the structural morphology and phase compositions of the final products. The results show that the tubular cells in bulk charcoal are converted into lots of SiC hollow fibers with pore diameters of 10–50 μm and lengths ranging from hundreds of μm to several mm. Resulting SiC hollow fibers consist of β-SiC with a minute amount of α-SiC. The formation mechanism of SiC hollow fibers is based on the gas–solid reaction between SiO and carbon.     

钴酸锂的再生及其电化学性能

采用提取的含少量Co3O4的LiCoO2为原料,在不同温度下合成正极材料LiCoO2,烧结时间为12 h,并采用XRD和SEM技术研究合成的LiCoO2的晶相结构与微观形貌。结果发现:烧结温度对LiCoO2的晶体结构影响较大,烧结温度越高,LiCoO2的层状结构发育越完整。循环伏安曲线很好地反映了再生LiCoO2的脱/嵌锂行为。将LiCoO2样品做成电池进行电化学检测,结果发现,烧结温度为850℃的样品首次放电容量为151mA.h/g,30次循环之后,放电容量仍有141mA.h/g,表现出良好的电化学性能。     

Gd0.8Sr0.2CoO3阴极的甘氨酸-硝酸盐法制备及性能研究

为探索适于中温条件下使用的固体氧化物燃料电池的阴极材料,用甘氨酸-硝酸盐法(GNP法)制备了Gd0.8Sr0.2CoO3(GSC)阴极粉体,用X-ray衍射考察了GSC的成相温度.采用丝网印刷法将GSC沉积在(Sm2O3)0.2(CeO2)0.8(SDC)圆片上,制成对称阴极,在不同温度下烧结.用交流阻抗谱从500℃到750℃测量了GSC阴极和SDC电解质之间的界面电阻.结果表明,用甘氨酸-硝酸盐法制备的GSC粉体的成相温度比传统固相法降低了400℃～500℃;700℃时,GSC阴极的界面电阻仅为0.26 Ω·cm2.     

导流槽阴极导杆安装方式对阴极表面电流分布的影响

将某厂现有的160kA Hall—Heroult铝电解槽改造成导流槽后，在阴极上表面和阳极底面呈斜坡状的条件下，计算了采用不同阴极导杆安装方式时阴极的电位和电流分布，即通过建立导流槽内部从阳极到阴极的一个半切片电热场模型，用有限元法分别对水平和平行于阴极斜坡两种不同导流槽阴极导杆的安装方式下阴极电位和表面电流密度分布进行了计算。结果表明，不同的阴极导杆安装方法对导流槽阴极的总电位降大小没有明显影响，但是水平阴极导杆安装更有利于阴极表面电流密度的均匀分布。     

高密度锂离子电池正极复合材料LiFePO4/C

以FeC2O4-2H2O、NH4H2PO4、Li2CO3和乙炔黑为原料,采用两步固相反应法制备了高密度LiFePO4/C正极复合材料.利用差热(DSC),热重(TGA)和X射线衍射(XRD)等分析手段具体探讨了第一步固相反应中可能存在的反应过程和中间产物.利用扫描电镜表征了复合材料LiFePO4/C中LiFePO4微粒形貌和接触状态.结果表明,乙炔黑的含量是影响LiFePO4微粒尺寸和微粒间接触界面的重要因素.在一次热处理的基础上,二次球磨和烧结有利于第二次固相反应过程中反应物质的接触和传质,较一步固相法提高了生成的LiFePO4的振实密度.当乙炔黑的含量(质量分数)为0.1%～1.5%时,两步固相法所制正极材料LiFePO4/C的振实密度可达到1.7 g/cm3,初次放电容量达到105 mA.h/g.     

Synthesis and characterization of La0.8Sr0.2MO3−δ (M=Mn, Fe, or Co) cathode materials by induction plasma technology

In this work, nanopowders of perovskite cathode materials (La_0.8Sr_0.2MnO_3−δ, La_0.8Sr_0.2FeO_3−δ, and La_0.8Sr_0.2CoO_3−δ), for use in solid oxide fuel cells (SOFC), were successfully synthesized, using induction plasma techniques. Their compositions, structures, morphology, particle size distributions, and BET specific surface areas were determined for comparison with their counterparts prepared by the Pechini method and by the glycine-nitrate combustion (GNC) technique. The particle sizes of the plasma-synthesized powders are mostly around 63 nm. These plasma-synthesized powders are generally globular, their BET specific surface areas being about 26 m²g⁻¹, approximately twice those of powders prepared by the GNC and Pechini methods. These plasma-synthesized powders are readily reproducible and are not agglomerated. Their individual particle sizes and distributions are very independent of their composition.