共查询到20条相似文献,搜索用时 15 毫秒
1.
Influences of heat treatment on electrochemical characteristics of La0.75Mg0.25Ni2.8Co0.5 hydrogen storage electrode alloy 总被引:1,自引:3,他引:1
1 INTRODUCTIONDuringthelastdecade ,thedemandforthenickel/metal hydride (Ni/MH )secondarybatterieshasbeengrowingrapidlybecauseoftheirhighenergydensity ,highHRD ,longcharge dischargecyclelifeandfriendlyenvi ronmentalproperties[14 ] .Hydrogenstoragealloys ,astheneg… 相似文献
2.
The present work focuses on the structural stability upon hydrogenation of three typical La–Mg–Ni-based alloys:La_(2-)Mg Ni_9,La_3Mg Ni_(14)and La_4Mg Ni_(19).Structural changes during gaseous and electrochemical cycles were characterized,and the influence of the structure distortion on the hydrogen storage properties was concerned.Hydrogen-induced amorphization(HIA)and disproportionation of the three alloys have occurred during both the gaseous and electrochemical cycles.Structural stability of the phase structures in the La–Mg–Ni system is found to follow the order:La Ni_(5-)[(La,Mg)_5Ni_(19)[(La,Mg)_2Ni_7[(La,Mg)Ni_3[(La,Mg)Ni_2.HIA increases thermal stability of the metal hydrides and difficulty to dehydrogenation and leads to degradation of both the gaseous and electrochemical capacities.Interestingly,La_2Mg Ni_9with poor stability presents elevated discharge capability even at 60°C which can be attributed to increase in the hydrogen desorption capability and inhibition of the self-discharge induced by severe HIA at higher temperatures.In addition,HIA in the electrochemical reactions is obviously weaker than the extent during the gaseous cycles,which is mainly due to the slower hydrogenation speed.The development of HIA in the gaseous and electrochemical process is considered to follow the direct and gradual modes,respectively. 相似文献
3.
The Mg0.9Ti0.1Ni1-xPdx (x= 0, 0.05, 0.1, 0.15) hydrogen storage electrode alloys were prepared by mechanical alloying. The main phases of the alloys were determined as amorphous by X-ray diffraction(XRD). The corrosion potentials of the alloys were measured by open circuit potential measurements and the values are -0.478, -0.473, -0.473 and -0.471 V (vs Hg/HgO electrode) for x=0, 0.05, 0.1, 0.15, respectively. The corrosion currents of the studied alloys were obtained by non-linear fitting of the anodic polarization curve using Bulter-Volmer equation and Levenberg-Marquardt algorithm, which were obtained after different cycles. The initial corrosion currents of the alloys are decreased with the increasing of Pd content. The increasing of Pd content in the alloys inhibits the corrosion rates of the electrode alloys with the progress of cycle number. The electrochemical impedance spectroscopy(EIS) was conducted after open circuit potential of the alloys stabilizing. The impedance data fit well with the theoretical values obtained by the proposed equivalent circuit model. The corrosion resistances and the thickness of surface passive film of the alloys, which were deduced by the analyses of EIS, are enhanced with the increasing of Pd content in the alloys, which are consistent with the results of corrosion rates obtained from anodic polarization measurements. 相似文献
4.
In this paper, the Co-free hydrogen storage alloys with the nominal compositions of La0.75R0.05Mg0.20Ni3.40Al0.10(R = La, Nd and Sm) were prepared by induction melting, and then the phase structure and electrochemical properties of these alloys were comparatively investigated. It is found that the alloys mainly consist of(La, Mg)2Ni7phase, La Ni5 phase and(La, Mg)5Ni19phase.Refinement results further show that Nd substitution for La remarkably promotes the formation of La Ni5 phase, while Sm is beneficial for the formation of(La, Mg)5Ni19phase.At discharge current density of 1,875 m A g-1, the highrate dischargeability(HRD) of alloy electrodes increases by 13.9 % and 6.5 % with La substituted by Nd and Sm,respectively. The electrochemical kinetic measurements reveal that the exchange current density(I0), charge transfer resistance(R) and hydrogen diffusion coefficient(D) for the alloy electrode are all facilitated with Nd and Sm partial substitution for La. Subsequently, a linear correlation between the HRD1875 and the corresponding I0/D is found. 相似文献
5.
The influence of the addition of Cu(OH)2 to 6 mol/L KOH alkaline electrolyte on the electrochemical properties of La2Mg0.9Al0.1Ni7.5Co1.5 hydrogen storage alloy electrode was investigated by electron probe X-ray microanalysis(EPMA), X-ray diffraction(XRD) and electrochemical measurements. EPMA micrographs and XRD patterns show that the surface of the hydride electrode is plated by metal copper film. The thickness and compactness of Cu film increase with the increment of charge-discharge cycle number. The copper film of the hydride electrode surface can keep the hydrogen storage alloy particle in the electrode interior from oxidizing availably. The addition of Cu(OH)2 to alkaline electrolyte lowers the activation property and the high rate dischargeability of the La2Mg0.9Al0.1Ni7.5Co1.5 hydride electrode, but has no negative effect on the maximum discharge capacity of the hydride electrode. Moreover, it is effective to improve the cyclic stability of the hydride electrode utilizing electrodeposit Cu film on theLa2Mg0.9Al0.1Ni7.5Co1.5 hydride electrodes surface. 相似文献
6.
Yang-huan ZHANG Long-wen LI Dian-chen FENG Peng-fei GONG Hong-wei SHANG Shi-hai GUO 《中国有色金属学会会刊》2017,27(3):551-561
Nanocrystalline and amorphous LaMg11Ni+x% Ni (x=100, 200, mass fraction) alloys were synthesized by mechanical milling. The electrochemical hydrogen storage properties of the as-milled alloys were tested by an automatic galvanostatic system. The gaseous hydrogen absorption and desorption properties were investigated by Sievert's apparatus and differential scanning calorimeter (DSC) connected with a H2 detector. The results indicated that increasing Ni content significantly improves the gaseous and electrochemical hydrogen storage performances of the as-milled alloys. The gaseous hydrogen absorption capacities and absorption rates of the as-milled alloys have the maximum values with the variation of the milling time. But the hydrogen desorption kinetics of the alloys always increases with the extending of milling time. In addition, the electrochemical discharge capacity and high rate discharge (HRD) ability of the as-milled alloys both increase first and then decrease with milling time prolonging. 相似文献
7.
Sheng-Long Lee Fu-Kai Hsu Wen-Chi Chen Chih-Kuang Lin Jing-Chie Lin 《Intermetallics》2011,19(12):1953-1958
A novel method to improve the cycling capacity degradation of Mg2Ni-based hydrogen storage alloy by means of composite materials has been proposed. The new composites Mg2Ni-x mol% Mg3AlNi2 (x = 0, 15, 30, 60, 100) were prepared by means of combining electric resistance melting with isothermal evaporation casting process (IECP). Phase analysis and microstructure were investigated by SEM and TEM observations. Results showed that the cycling stability of the alloy with Mg3AlNi2 was superior to that of Mg2Ni. XPS analysis revealed that the formation of an Al oxide film during cycling could enhance the anti-corrosion of the surface of the composites. Among the obtained capacity retaining rates, Mg2Ni-15 mol% Mg3AlNi2 composite had the best anti-corrosion performance. This composite has kept 76% of its maximum discharge capacity (50 mA hg?1) at 25th cycle compared to 20% for Mg2Ni. The enhancement of the cycling stability of the electrode alloy with 15 mol% Mg3AlNi2 can be ascribed to the decrease in the rate of pulverization of the alloy during cycling, which is considered as the factor in the improvement of the electrochemical properties of the Mg3AlNi2-containing alloys. 相似文献
8.
1 INTRODUCTIONPresently ,therearetwokindsofhydrogenstor agealloys (AB5andAB2 )usedinnickel metalhy dride (Ni/MH)battery .AB2 typehydrogenstoragealloyhasworseactivationperformanceandlowerini tialcapacitythoughitscapacityishigherandlifeislongerthanAB5alloy .Atthesametime ,AB2 typehydrogenstoragealloyismoreexpensivethanAB5typehydrogenstoragealloy .AlltheaboveaspectsembarrasstheactualapplicationofAB2 typehydrogenstoragealloy .PropertiesofAB2 typehydrogenstor agealloy ,suchascapacity ,… 相似文献
9.
Electrochemical hydrogen storage properties of La0.95Mg2.05Ni9 alloy prepared by mechanical alloying
1 INTRODUCTIONTheMg basedhydrogenstoragealloysastheac tivematerialsofmetalhydrideelectrodeshaveattract edattentionbecauseofhighertheoreticalcapacitiesforhydrogenabsorption/desorption ,andthelowerpricecomparedwiththeotherhydrides[17] .Recent ly ,thecharge dischargepropertiesofMg basedalloysatroomtemperaturehavebeengreatlyimprovedbysomeresearchers[813] .Inparticular ,theMg Ni REsystemalloyisoneofthemost promisinghydrides[14 16 ] .Tanakaetal[15] reportedthatthenanocrystallineMg Ni RE(R… 相似文献
10.
Structure and electrochemical properties of La-Mg-Ni system hydrogen storage alloys with different Co contents 总被引:1,自引:0,他引:1
1 INTRODUCTIONTo increase the discharge capacity of nickel/metal-hydride ( Ni/ MH) batteries , new types ofhydrogen storage alloys with higher energy densityhave been paid considerable attention by research-ers . Particularly , recent investigations on theR-Mg-Ni (R=rare earth or Ca element) systemhydrogen storage alloys have led to a newseries ofternary alloys with a high hydrogen storage capaci-ty[1 3]. Kohno et al[4]found that the maxi mumdis-charge capacity of the La0 .7Mg0 .3Ni2 … 相似文献
11.
12.
《Intermetallics》2016
A simple method was developed for improving the hydrogen storage properties through adding nano Ni–Al compounds using as a stable catalyst to the La2Mg17 alloys by a PVD method. With the trace addition of the catalyst, hydrogen absorption and desorption rate are all substantially improved for the La–Mg based alloys. The alloys formation process has been determined, and the activity energy of the hydride dehydrogenation reaction before and after Ni–Al nanocrystalline addition was also calculated. 相似文献
13.
《中国有色金属学会会刊》2015,(6)
采用合金熔炼及退火处理的方法制备La-Mg-Ni系A2B7型La0.8+xMg0.2–xNi3.5(x=0-0.05)电极合金,并研究不同的化学计量比La/Mg对该合金的相结构和电化学性能的影响。通过X射线衍射(XRD)和扫描电子显微镜(SEM)对合金进行表征。结果表明:合金包含(La,Mg)2Ni7和La Ni5两个主相以及一些残余相La Ni3。随着La/Mg比率的增大,合金中的(La,Mg)2Ni7相含量降低,而La Ni5和La Ni3相的含量升高。La/Mg比的变化也使得合金电极的电化学性能发生显著变化。随着La/Mg比率的增加,铸态及退火态合金的放电容量降低,而循环稳定性明显改善。此外,合金电极的高倍率放电性能(HRD)、电化学阻抗谱(EIS)、Tafel极化曲线以及电势阶跃的测量均表明La/Mg比率的增加提高了合金的电化学动力学性能。 相似文献
14.
ZHOU Liu LU Dongsheng LI Weishan HU Shejun CAI Yuepeng TANG Renheng XIAO Fangming 《稀有金属(英文版)》2005,24(4):336-340
1 Introduction AB5-type rare-earth-based hydrogen storage al- loys have widely been used as negative electrode materials for nickel-metal hydride batteries due to their inherent advantages, especially high hydrogen storage capacity, easy activation and lo… 相似文献
15.
16.
In order to improve the electrochemical performances of La-Mg-Ni based electrode alloys with PuNi3-type structure, a trace of boron was added in La0.7Mg0.3Ni2.55Co0.45 alloy. The La0.7Mg0.3Ni2.55Co0.45Bx(a=0, 0.05, 0.1, 0.15 and 0.2) alloys were prepared by casting and rapid quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were investigated. The effects of rapid quenching on the microstructures and electrochemical performances of the above alloys were investigated. The results show that the as-cast and quenched alloys are composed of (La, Mg)Ni3 phase, LaNi5 phase and LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloys containing boron, and the Ni2B phase in the B-contained alloys nearly disappears after rapid quenching. Rapid quenching increases the amount of the LaNi2 phase in the B-free alloy, but it decreases the amount of the LaNi2 phase in the boron-containing alloys. The effects of rapid quenching on the capacities of the boron-containing and boron-free alloys are different. The capacity of the B-free alloy monotonously decreases with increasing quenching rate, whereas the capacities of the B-contained alloys have a maximum value with the change of the quenching rate. The rapid quenching can improve the stability of La-Mg-Ni based electrode alloy but lowers the discharge plateau voltage and decreases the plateau length. The effect of rapid quenching on the activation capabilities of the alloys was complicated. 相似文献
17.
MA Zhihong QIU Jufeng CHEN Lixin and LEI YongquanBaotou Hengyitong Rare Earths Co. Ltd. Baotou ChinaBaotou Research Institute of Rare Earths Baotou ChinaDepartment of Materials Science Engineering Zhejiang University Hangzhou China 《稀有金属(英文版)》2005,(1)
The nonstoichiometric La-rich mischmetal (designated by Ml)-based hydrogen storage alloy with a composition of Ml(Ni0.64Co0.20Mn0.12Al0.04)4.76 was prepared by arc melting and annealed at 1173 K for 10 h to 相似文献
18.
AB5 hydrogen storage alloys La0.54Ce0.28Pr0.18Ni4-xCo0.6Mno35Alx (x=0.1, 0.2, 0.3) were prepared by arc melting method under an Ar atmosphere. The results show that the contents of Ni and Al have obvious influences on the microstructure and electrochemical properties of the alloys. Both the lattice parameters and the cell volumes decrease with decreasing x value. Moreover, the discharge capacity at different temperatures, the high rate discharge property, and the cycling life of the alloy electrode are also in close relationship with the x value. When x value increases from 0.1 to 0.3, the discharge capacities with a discharge current density of 60 mA/g slightly decreases at 25℃, but evidently deteriorates at -40℃, the high-rate property gravely decreases, and the cycle life of the alloy electrode is improved in some extent. Therefore, it is meaningful to control Al content for the AB5 hydrogen storage alloys used in Ni/MH batteries. 相似文献
19.
In the present study, corrosion-protective microarc oxidation (MAO) coatings were prepared on AZ31B, AZ80, and ZK60 cast magnesium alloy substrates in an alkaline silicate electrolyte. The corrosion performances of the uncoated and MAO-coated alloys were investigated using electrochemical and salt spray chamber corrosion tests. The microstructure characterization and experimental results show that among the three alloys studied, the ZK60 Mg alloy exhibited the best and AZ31B the least corrosion resistance under the salt spray conditions. The MAO coating provided robust corrosion protection of the Mg substrates and resulted in a significant decrease in the corrosion rate of the alloys by 3–4 orders of magnitude. The MAO coating on ZK60 alloy showed better corrosion protectiveness than that on the AZ series alloys due to the incorporation of different alloying elements in the coating, especially the Zn and Al elements, which are from the Mg substrate. The corrosion performances and mechanisms of the uncoated and MAO-coated Mg alloys are interpreted in terms of the microstructure and phase/chemical compositions of both the substrates and coatings. 相似文献
20.
MAZhihong QIUJufeng CHENLixin LEIYongquan 《稀有金属(英文版)》2005,24(1):65-70
The nonstoichiometric La-rich mischmetal (designated by Ml)-based hydrogen storage alloy with a composition of Ml(Ni0.64Co0.20Mn0.12Al0.04)4.76 was prepared by arc melting and annealed at 1173 K for 10 h to investigate the effect of annealing treatment on the microstructure and electrochemical characteristics of the alloy. X-ray diffraction analysis showed that annealing can cause a release of the crystal lattice strain and an increase in amounts of the La2Niγ-type second phase inMl(Ni0.64Co0.20Mn0.12Al0.04)4.76 alloy. Scanning electron microscopy and electron probe microanalysis examinations indicated that annealing leads to disappearance of the dendrite structure in the as-cast alloy, growth of crystal grain, and decrease of composition segregation. The annealing at 1173 K for 10 h flattened and extended the potential plateau and increased the maximum discharge capacity to 328 mA-h/g from 310 mA-h/g and the cycling life. The mechanism of the improvement in electrochemical characteristics was discussed based on the alloy microstructure change induced by annealing. 相似文献