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1.
采用三角波电位扫描、X射线衍射及恒流充放电曲线法研究了在氢氧化镍电极中添加Co( OH) 2 和 Ni粉后对电极性能的影响 .结果表明 ,氢氧化镍电极中加入质量分数为 8% Co( OH) 2和 13% Ni粉时 ,电极的放电容量最高 ,电极在充放电循环过程中的膨胀最小 .  相似文献   

2.
采用微乳法制备纳米Ni(OH)2,用X射线衍射、扫描电子显微镜、透射电子显微镜、恒流充放电、循环伏安、交流阻抗等测试技术研究了纳米Ni(OH)2的微观结构、表面形貌和电化学性能. 结果表明,140 ℃水热和微乳/水热2种方式处理得到的纳米Ni(OH)2具有不同形貌特征. 水热和微乳/水热处理虽然不影响纳米Ni(OH)2的活化性能,但对纳米Ni(OH)2的放电比容量影响很大,采用140 ℃水热和微乳/水热处理比单纯的微乳法制备得到的纳米Ni(OH)2的放电比容量分别提高了24.6和74.8 mA·h/g. 处理后的纳米Ni(OH)2的循环伏安峰电流增大、电荷转移电阻由2.633 Ω分别降至2.464和1.679 Ω.  相似文献   

3.
以多孔氧化铝为模板, 在不同溶液浓度下, 用化学沉积法制备了氢氧化镍纳米管. 采用XRD, SEM, TEM和HRTEM等手段, 对产物的物相、表面形貌及微结构进行了表征. 结果表明所得产物是高纯度的氢氧化镍纳米管, 外径约为180~220 nm, 管壁厚20~30 nm. 将所制备的氢氧化镍纳米管制成电极, 其电化学性能测试表明, Ni(OH)2纳米管的中空结构特点, 能够有效地提高镍电极的充电效率、放电比容量、高倍率及高温放电性能. 机理分析表明中空结构的Ni(OH)2纳米管对于提高碱性二次电池的综合性能有着极为重要的意义.  相似文献   

4.
采用共沉淀法在一定温度、pH值和搅拌速度下合成了掺锰氢氧化镍活性材料。对合成产品进行了X射线衍射分析和电化学性能分析。XRD分析表明,掺锰氢氧化镍形成了α和β混合相的晶体结构。通过对其进行充放电测试,结果表明,氢氧化镍活性材料中添加适量的锰有利于提高镍电极的电化学性能。研究结果表明,当锰摩尔分数为10%时,镍电极的充电平台最低,析氧平台提高;放电平台较高,在1.2V以上,放电态电阻较小,放电比容量达到243.21mA·h/g;由于添加锰元素可能形成了部分α-Ni(OH)2,使摩尔镍电子转移数较大,接近1。对添加锰的镍电极进行多次循环测试表明其循环性能较好,容量稳定。  相似文献   

5.
Ni(OH)2纳米管的制备、表征及电化学性能   总被引:3,自引:2,他引:3  
以多孔氧化铝为模板, 在不同溶液浓度下, 用化学沉积法制备了氢氧化镍纳米管. 采用XRD, SEM, TEM和HRTEM等手段, 对产物的物相、表面形貌及微结构进行了表征. 结果表明所得产物是高纯度的氢氧化镍纳米管, 外径约为180~220 nm, 管壁厚20~30 nm. 将所制备的氢氧化镍纳米管制成电极, 其电化学性能测试表明, Ni(OH)2纳米管的中空结构特点, 能够有效地提高镍电极的充电效率、放电比容量、高倍率及高温放电性能. 机理分析表明中空结构的Ni(OH)2纳米管对于提高碱性二次电池的综合性能有着极为重要的意义.  相似文献   

6.
外掺Y2O3对镍氢电池正极高温性能的影响   总被引:10,自引:2,他引:8  
研究了外掺Y2O3对镍氢电池镍正极高温性能的影响. 通常镍正极在高温下放电比容量会骤然降低, 为了提高其高温性能, 进行了球型Ni(OH)2外掺不同比例Y2O3的实验, 对压制的镍电极在不同温度下的充放电情况进行了细致的研究. 研究发现外掺Y2O3的球型Ni(OH)2电极比普通球型Ni(OH)2电极的放电比容量在高温下要高出很多, 在0.2 C充放电情况下外掺1%是最佳比例, 它比普通球型Ni(OH)2电极的放电比容量要高出35%以上, 在1 C充放电情况下外掺0.2%是最佳比例, 它比普通球型Ni(OH)2电极的放电比容量要高出15%以上. 同时对外掺Y2O3提高镍正极放电比容量的原因也进行了初步探讨.  相似文献   

7.
采用缓冲溶液法制备复合掺杂Mn、Mg的正极材料Ni0.82Mn0.18-xMgx(OH)2(x=0.06、0.09、0.12)。采用XRD、XPS和SEM等测试表征材料的晶体结构、锰价态和形貌,采用循环伏安和恒流充放电测试研究Mn、Mg不同掺杂比例对氢氧化镍电化学性能的影响。结果表明,Mn、Mg掺杂样品均为β相,晶粒细化;Ni0.82Mn0.09Mg0.09(OH)2样品具有优异的电极反应可逆性和充放电性能,100 mA·g^-1电流密度下的放电比容量(290.6 mAh·g^-1)优于商用β-Ni(OH)2(281.1 mAh·g^-1);且500 mA·g^-1电流密度下循环30圈后,Ni0.82Mn0.09Mg0.09(OH)2的放电比容量未见衰减,其循环稳定性优于商用β-Ni(OH)2。  相似文献   

8.
化学共沉淀法合成氢氧化镍,并在表面用"梯度共晶法"复合包覆Co(OH)x+Yb(OH)3。XRD,XPS,SEM表征结果表明:制备的样品为六方球形β-N i(OH)2,表面包覆了Co(OH)x+Yb(OH)3,Co的存在形式应该主要为Co2+及少量的Co3+。65℃下0.2C,1C和3C恒电流充放电时,复合包覆Co(OH)x+2%Yb(OH)3的氢氧化镍的放电比容量和放电效率最大。大倍率充放电和循环稳定性等性能也得到改善。  相似文献   

9.
以NiCl2、Co(NO3)2、Na2CO3为主要原料,采用超声波辅助沉淀法制备了混合相纳米Ni(OH)2,研究了Co掺杂比例、缓冲剂Na2CO3用量及反应物Ni2+浓度对Ni(OH)2的晶相结构、形貌、粒径及电化学性能的影响。结果表明,混合相结构的α-Ni(OH)2成分随Co掺杂比例增大而增加。较高的CO32-和Ni2+浓度有利于α-Ni(OH)2的生成。TEM测试表明,样品晶粒呈针状形态,其长径比随着Na2CO3用量增加而减小,平均粒度在60~90 nm之间。将纳米样品以8wt%与工业用微米级β球镍混合制成复合电极,其电极的放电比容量随Na2CO3用量的增加先增大后减小。当Ni2+浓度为0.4 mol.L-1、Na2CO3用量为0.5 g时,其电极(Co含量1.02wt%)的充电效率最高,放电比容量最大,0.5C倍率下高达306.9 mAh.g-1,比纯球镍电极提高30%。探讨了复合电极能较大幅度提高放电比容量的机理,提出纳米α-Ni(OH)2同时充当活化中心起催化作用的观点。  相似文献   

10.
为了改善Ni(OH)2的电化学性质,提高锌镍电池的充放电性能,用化学共沉淀法合成了混合铝镍氢氧化物Ni/Al(OH)x.用XRD和FTIR表征了Ni/Al(OH)x样品的晶体结构及IR光谱特征;测试了用Ni/Al(OH)x为正极活性物质的Zn/Ni实验电池的充放电性能.研究结果表明:所合成的Ni/Al(OH)x具有α-Ni(OH)2的晶体结构;Ni/Al(OH)x活性物质在充放电过程中主要为γ/α循环,以Ni/Al(OH)x作为正极活性物质的Zn/Ni试验电池具有优良的循环性能,其最高放电比容量为379mA·h/g.  相似文献   

11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.  相似文献   

12.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。  相似文献   

13.
翟宗玺  刘树深  夏树屏 《化学学报》1990,48(10):946-950
用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。  相似文献   

14.
Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.  相似文献   

15.

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

  相似文献   

16.
Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.  相似文献   

17.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.  相似文献   

18.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

19.
20.
The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe2O3. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

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