Evaluation of Self-Field Distributions for Bi2223 Tapes With Oxide Barriers Carrying DC Transport Current

For AC loss reduction in Bi2223 tapes subjected toan AC external magnetic field, twisting the superconductingfilaments and/or introducing oxide layers as highly resistivebarriers around each filament are required. However, thestructure of barrier tape becomes very complex and longitudinaluniformity of both transport property and tape structure could beeasily deteriorated. To improve the current transport capabilityand its longitudinal uniformity for barrier tape for AC use, simpleand non-destructive techniques to characterize them should beindispensable. In this paper, we examined the self-fielddistributions for Bi2223 tapes with oxide barriers carrying DCtransport current by a scanning Hall-probe microscopy (SHM).Non-twisted and twisted 19-filamentary tapes with SrZrO3 +Bi2212 barriers were prepared by powder-in-tube process. Thedistributions of self-field in perpendicular to the broader face of atape carrying DC current below critical current Ic was measuredat 77 K by SHM with an active area of 50 μm × 50 μm, at 0.5 mmaway from the tape surface. Based on the measured self-fielddistributions, longitudinal non-uniformity of transport propertiesand the presence of local defects to obstruct the current transportin barrier tapes were investigated

Some Effects of Co on the Electrochromic Properties of NiO xH y Film

本文利用阴极化电沉积法在抛光镍板及ＩＴＯ玻璃表面制备了含Ｃｏ量为１６．２％的ＮｉＯｘＨｙ薄膜，薄膜厚度分别为４２ｎｍ、２１ｎｍ，采用透射光谱以及线性电位扫描、交流阻抗和阳极稳态极化曲线等测试技术，考察了Ｃｏ对ＮｉＯｘＨｙ薄膜电致变色性能的影响，光谱测试范围为３００～２５００ｎｍ．结果发现：Ｃｏ能降低薄膜着色态在可见光区及部分近红外区的透过率，通过电压调节不仅可以调光而且可望能够控温；同时Ｃｏ还能降低ＮｉＯｘＨｙ薄膜电致变色电位，升高薄膜氧化着色过程中的氧析出过电位，对薄膜的电致变色性能有改进作用，但降低了着色过程中质子的扩散系数．Some effects of Co addition upon the electrochromic characteristics of a nic_kel hydroxide film were studied. The films were electrodeposited on both polished Ni plate and conductive ITO glass. The electrochemical behaviors were investigated using the film on Ni plate by linear potential sweep, a.c. impedance, and anodic polarization curves for OER(oxygen evolution reaction). It was found that Co can lower the working voltage and raise the oxygen overpotential, but has little effect on the reaction kinetics. It was also found that the Co can improve the optical properties of the electrochromic film.作者联系地址：南开大学新能源材料化学研究所Author's Address: Inst. of New Energy Material Chem. Nankai Univ., Tianjin 30007

The Effect of Co on the Proton Diffusion Coefficient for the Ni(OH)2 Electrodes

本文采用恒电位阶跃、循环伏安及恒电流放电法，考察含Ｃｏ量０％～５３％的Ｎｉ（ｏＨ）_２电极充放电过程中质子的扩散系数：充电过程该值为１０－９～１０－１０ｃｍ２／ｓ，放电过程则为１０（－１１）ｃｍ２／ｓ．数据处理时对文献中有关公式进行了修正．The diffusion coefficients of protons moving in the Ni(OH)2 electrodes have being investigated by constant current,cyclic voltammetry and potential step technineques.The electrodes were prepared by cathodic deposition and their active material contained 0～53% cobalt.It was found that the diffusion coefficients are about 10(-9)～10(-10) cm2/s during charging and about 10(-11) cm2/s during discharging.Moreover the value increases with the increacing content of Co in the electrodes.During the calculation,the relevant fomulars were modified especially the wrong fomular for constant current methode.作者联系地址：南开大学新能源材料化学研究所Author's Address: Institute of New Energy Material Chemistry,Nankai University,Tianjin 30007

Oxygen Evolution Behavour on Ni Electrode in KOH Solution

用恒电流法测试在２２～７０℃之间电解３０ｗｔ．％ＫＯＨ水溶液时Ｎｉ阳极的稳态极化曲线以及该过程的交换电流密度ｉ０，Ｔａｆｅｌ斜率ｂ，传递系数β和不同电流密度下的析氧过电位随电解温度的变化关系结果发现：４０℃是各参量随温度变化的一个突出变点，４０℃以下，高过电位区的Ｔａｆｅｌ斜率达１２０ｍＶ以上，低过电位区的反应活化能Ｅａ为７９．８８ｋＪ／ｍｏｌ，而４０℃以上时，上述两参数分别为６０～７０ｍＶ和５５．３２ｋＪ／ｍｏｌ．另外两温度区间的（η／Ｔ）１及其随ｌｇｉ的变化也有显著差别The steady_state polarization curves of oxygen evolution were measured at temperatures between 22～70 ℃ on Ni electrode in 30 wt.% KOH solution by galvanostat methode. The exchange current densities, Tafel slopes and transfer coefficients were studied. It was found that 40 ℃ is a special temperature, near which the kinetic parameters change abrupdy. The Tafel slopes for oxygen evolution reactions at higher overpotentials change from more than 120 mV to about 70 mV when the temperature raises to 40～70 ℃ from 22～35 ℃. Simultaneously, the heat of activation is changes from 79.88 kJ/mol to 55.32 kJ/mol. Moreover, the -(η/Τ) i and how it changes with lg i are quite different in the two temperature ranges: The slope of -(η/Τ) i vs. lg i is 4.63 at the lower temperatures, while at the higher temperatures it is only -0.455.作者联系地址：南开大学新能源材料化学研究所Author's Address: Inst. of New Energy Material Chem. Nankai Univ. Tianjin 30007

Corrosion Behavior of Mg_(2-x)La_xNi and Mg_(2-x)Ce_xNi Hydrogen Storage Alloy

应用电化学方法研究了Mg2-xLaxNi及Mg2-xCexNi储氢合金的腐蚀性能.恒电位极化和交流阻抗测试表明,经Ce或La取代后的合金,其前者腐蚀电流及电化学极化电阻均随Ce取代量增加而降低,而后者的腐蚀电流却随La取代量的增加而增加,但极化电阻则呈先降后升趋势.合金极化后SEM测试显示,经Ce取代后合金表面较平整,而用La取代的则明显有裂纹.作者认为这主要与La、Ce的氧化物的结构有关.The corrosion behavior of Mg-base hydrogen storage alloys has been investigated by potentiodynamic polarization and EIS. The results showed that the corrosion current density (i_(corr) ) and the electrochemical polarized resistance of Mg_(2-x)Ce_xNi alloys decreased with x increase, while i_(corr) of Mg_(2-x)La_xNi alloys increased and the electrochemical polarized resistance of Mg_(2-x)La_xNi alloys increased first, then decreased with x increase. SEM results showed that the surface of Mg_(1.85)Ce_(0.15)Ni alloy was relatively even while the surface of Mg_(2-x)La_xNi alloy had remarkedly cracks. The different behavior between Ce and La may be relevant to the structure of Ce, La oxides.作者联系地址：南开大学新能源材料化学研究所,南开大学新能源材料化学研究所,南开大学新能源材料化学研究所,南开大学新能源材料化学研究所 天津300071 ,天津300071 ,天津300071 ,天津300071Author's Address: College of Chemistry Institute of New Energy Material Chemistry,Nankai University,Tianjin 300071,Chin

Corrosion Behavior of Mg_(1.85)Mm_(0.15)Ni Hydrogen Storage Alloy Modified by Electroless Cu in CH_3OH·H_2O Solutions

　采用稳态极化曲线法和交流阻抗法研究了在甲醇 水不同含量镀液中化学镀铜的Mg1.85Mm0.15Ni(Mm∶富铈混合稀土)储氢合金于强碱性溶液中的抗腐蚀性能.结果表明,对甲醇＿水体系化学镀铜,合金的抗腐蚀性可进一步改善.其中以甲醇体积比含量为40%的镀液施镀的抗腐蚀效果最佳.稳态极化曲线测试给出,此时合金的腐蚀电流密度只有5.6mA·cm-2,相应的电化学反应阻抗为22.25Ω·cm2,而原粉的两者之值分别为11.7mA·cm-2和1.99Ω·cm2.The corrosion behavior of the Mg1.85Mm0.15Ni (Mm:Ce_rich mischmetal) alloy modified by electroless Cu coating in different CH3OH_H2O solutions has been investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. These results showed that the corrosion behavior was improved after electroless Cu. The potentiodynamic polarization and electrochemical impedance spectroscopy results showed that the alloy electrode had more promising anti_corrosion behavior after coated in a 40%CH3OH_H2O solution. The values of corrosion current density and electrode reaction resistance were 5.6 mA·cm-2(11.7 mA·cm-2 for uncoated alloy electrode) and 22.25 Ω·cm2 (1.99 Ω·cm2 for the uncoated alloy electrode), respectively.作者联系地址：南开大学能源材料化学研究所,南开大学能源材料化学研究所,南开大学能源材料化学研究所,南开大学能源材料化学研究所,南开大学能源材料化学研究所 天津300071 ,天津300071 ,天津300071 ,天津300071 ,天津300071Author's Address: College of Chemistry Institute of New Energy Material Chemistry, Nankai University, Tianjin 300071,Chin

Electrochemical Stability of PVA Alkaline Gel Polymer Electrolyte Membranes

应用溶解—铸膜法制备聚乙烯醇(polyvinylalcohol,PVA)碱性凝胶聚合物电解质(gelpolymerelectrolyte,GPE)薄膜.交流阻抗(EIS)测试表明,随着KOH含量的增加,该薄膜的离子电导率表现为先增大而后减小的变化趋势,当KOH含量为42%(bymass,下同)时,电导率达到最大值,为2.01×10-3S/cm.X射线衍射(XRD)结果表明,当膜中KOH含量大于20%时,晶态的PVA就逐渐转变为非晶态结构.又当KOH含量增加到一定值后,由于体系中未电离的非晶态KOH量的增多而导致离子电导率下降.循环伏安(CV)和拉曼光谱(Raman)结果表明,该薄膜具有很好的电化学稳定性,可应用于碱性二次电池.Polyvinyl alcohol (PVA) alkaline polymer gel electrolyte(GPE) membranes were successfully prepared by a solution-casting technique and their electrochemical stabilities were investigated. The electrochemical impedance spectrum (EIS) results showed that the ionic conductivity of the PVA alkaline GPE membranes first increased with the increase of KOH content, then decreased with the further increase of KOH. When the weight percentage of the KOH in the PVA alkaline GPE membrane approached to 42%, it exhibitedthe highest ionic conductivity of 2.01×10~(-3 ) S/cm at room temperature (R.T.). The X-ray diffraction (XRD) results revealed that with the increase of KOH the crystalline of the PVA was disrupted and converted into an amorphous phase. While the ionic conductivity decreased due to the increase of the amorphous unionized KOH in the membranes with the further increase of KOH. The cyclic voltammograms (CV) and Raman spectra indicated that the GPE membranes had promising electrochemical stabilities. It is suggested that the PVA alkalineGPE membranes could be used for practical applications in alkaline rechargeablebatteries.作者联系地址：南开大学新能源材料化学研究所,南开大学新能源材料化学研究所,南开大学新能源材料化学研究所,南开大学新能源材料化学研究所 天津300071 ,天津300071 ,天津300071 ,天津300071Author's Address: Institute of New Energy Material Chemistry, Nankai University, Tianjin 300071,Chin

The Study on the Synthesis and Electrochemical Property of K_2FeO_4

　本文主要研究了锂离子电池正极材料高铁酸钾的合成,表征和电化学性质.用次氯酸钾与硝酸铁于碱性介质中反应得到高铁酸钾粗品,重结晶后成纯度大于97%的产品,用XRD和FTIR等方法对高铁酸钾进行表征和分析.初步研究了K2FeO4/Li电池的充放电性能.The synthesis,characterization and electrochemical property of K2FeO4 for positive materal of lithium ion battery were studied. K2FeO4 with low purity was gained through the reaction of KCIO and Fe(NO3)3 in KOH solution and after recrystalization the purity of K2FeO4 reached 97%～98%. The methods of XRD and FTIR were used to measure the structure of K2FeO4 and its initial discharge performance was tested.作者联系地址：南开大学新能源材料化学研究所,南开大学新能源材料化学研究所,南开大学新能源材料化学研究所,南开大学新能源材料化学研究所,南开大学新能源材料化学研究所,南开大学新能源材料化学研究所,南开大学新能源材料化学研究所 天津300071 ,天津300071 ,天津300071 ,天津300071 ,天津300071 ,天津300071 ,天津300071Author's Address: Institute of New Energy Material Chemistry,Nankai University,Tianjin 300071,Chin