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The cold crucible levitation melting prepared LaNi3.2-xMn03Cox (x = 0.2 ∼ 0.8) series alloys, the system of Co substitution of Ni on the alloy structure, hydrogen storage performance and electrochemical properties. XRD analysis showed that the cast alloy by the La2Ni7 phase, LaNi5 phase and LaNi3 phase composition; PCT test shows that with the Co s...
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... (x = 0.2 ~ 0.8) series alloys in the discharge current of 80mAh / g activated under the conditions shown in Figure 3, the activation frequency (Na) and the maximum discharge capacity (Cmax) in Table 3 shown. Figure 3 and Table 3 shows that all alloys after 3 to 4 times you can charge and discharge cycles to reach its maximum discharge capacity, showing good activation performance. ...
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... = 0.2 ~ 0.8) series alloys in the discharge current of 80mAh / g activated under the conditions shown in Figure 3, the activation frequency (Na) and the maximum discharge capacity (Cmax) in Table 3 shown. Figure 3 and Table 3 shows that all alloys after 3 to 4 times you can charge and discharge cycles to reach its maximum discharge capacity, showing good activation performance. With the Co content increases, the alloy by the maximum discharge capacity 320.5mAh / g (x = 0.2) gradually reduced to 286.6mAh / g (x = 0.8), the maximum discharge capacity of alloy electrode with Co content of the relationship shown in Figure 4. Table 3 The Na and Cmax of the LaNi3.2-xMn0.3Cox（x=0.2~0.8）alloy ...
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Citations
... The substitution of La by Mm contributes most to the price of the final product without compromising the electrochemical characteristics, while partial substitution of Ni in the crystal lattice was shown to significantly improve the performance of the alloy [5]. Co, Al and Mn are known to increase the cell volume, decrease the volume expansion upon hydriding and decrease the corrosion rate, thus leading to higher electrochemical capacity and improved cycle life [6,7]. These elements are the most commonly used ones for substitution of Ni in commercial alloys for Ni-MH batteries [8]. ...
Hydriding/dehydriding properties of a series of LaNi5 based alloys were compared by applying both hydrogen gas phase and electrochemical hydrogen charge/discharge methods. The highest hydrogen absorption capacity of 1.4 wt.% H2 was found for LaNi4.3Co0.4Al0.3, although LaNi4.8Sn0.2 also reveals comparable hydrogen capacity (>1.3%). A significant difference in the hydriding kinetics was observed for all studied alloys before and after activation. The activated alloys (5 cycles at 65 °C, 40 atm. H2) reach their maximum capacities after less than a minute, whereas the pure LaNi5 alloy needs several minutes for complete hydriding. The electrochemical hydriding/dehydriding behavior of the alloys reveals superior performance of LaNi4.3Co0.4Al0.3 and LaNi4.8Sn0.2 compared to the other compositions studied, as the capacity of LaNi4.8Sn0.2 decreases by only 10% for 60 charge/discharge cycles at a current density of 100 mA/g. Good agreement between the hydrogen sorption kinetics of the alloys obtained electrochemically and from hydrogen gas phase has also been observed.
... (x = 0,2 ~ 0,8) hidrojen depolama alaşımını üretmişler, x=0,2 olan alaşımın maksimum deşarj kapasitesini 320,5 mA sa g -1 olarak bulmuşlardır. Ancak alaşım içerisindeki Co miktarının artırılması ile döngü kararlılığının artığı belirtilmiştir [52]. Hibrid elektrik araçları için çevrim yöntemi ve kısa D-boyutlu kapalı hücrenin güç verimi deneyleri ile Mm0,96Mg0,04Ni4,175Co0,325Mn0,4Al0,3 alaşımının, 25000 çevrim sonra başlangıç güç ve deşarj kapasitesi değerlerinin %80'ini koruduğu bulunmuştur. ...
Hidrojen depolama alaşımları şarj edilebilir Ni-MH pillerinin pratik uygulamaları için son zamanların çok geniş araştırma konusunu oluşturmaktadır. Bu derleme çalışmasında şarj edilebilir Ni-MH pilleri için AB5-tip, AB2-tip, TiV esaslı, R-Mg-Ni esaslı ve Mg-Ni esaslı hidrojen depolama alaşımlarının son yıllardaki gelişmeleri detaylı olarak anlatılmıştır. Son yıllarda gerçekleşen gelişmelere bağlı olarak var olan problemler ve ilgili sonuçlar sistematik olarak değerlendirilmiştir. Hidrojen depolama alaşımlarının, alaşım kompozisyonları, kristal yapıları ve elektrokimyasal özellikleri arasındaki bağlantı her bir alaşım çeşidi için tanımlanmış ve güç pilleri üzerinden analiz edilmiştir. Gelişen elektrikli araçlarda kullanımları için Ni-MH pillerindeki zorluklar bu çalışmada tartışılmıştır.
... As an excellent hydrogen storage material, metal hydride plays an important role in promoting the exploitation and utilization of hydrogen energy. 1 Recently, the demand for La-Mg-Ni-based hydrogen storage alloys, wherein La and Mg occupy the A-side position and Ni occupies the B-side position, has been steadily increasing because of their higher hydrogen storage capacity. 2,3 However, studies on La-Mg-Ni-based hydrogen storage alloys are still at an exploratory stage. The poor cyclic durability and the unclear correspondence between macroscopic properties and microstructures have hindered their use in various practical applications. ...
The feasibility of substituting nickel for cobalt in La-Mg-Ni-based hydrogen storage alloys to reduce material costs and improve electrochemical properties is investigated. The series of alloys with the chemical formula La(0.75)Mg(0.25)Ni(2.7+x)Co(0.4-x)Mn(0.01)Al(0.)3 (x = 0-0.4) that reflects the gradual substitution of Ni for Co are prepared by chemical co-precipitation plus reduction method. The detailed synthesis process, structure, morphology, electrochemical performance, and kinetic properties of the resulting alloy electrodes are discussed in terms of the variation in substitution amount of Ni for Co. Results reveal that the hydrogen storage alloy substituted with x = 0.1 exhibits the best overall electrochemical performance among all investigated samples, whereas the complete substitution of Ni for Co has no significant effect on electrochemical performance. Based on these results, a mechanism underlying the effect of substituting Ni for Co on the electrochemical performance of the resulting alloy is discussed in detail and effectively verified by conducting three electrochemical kinetic experiments. Complete substitution of Ni for Co is found to be suitable for reducing material costs and improving the overall electrochemical performances of La-Mg-Ni-based hydrogen storage alloys.
L'objectif du projet est de faire émerger de nouveaux alliages de type A,MgBx pro metteurs en termes d'applications électrochimiques, notamment en substituant ou remplaçant le lanthane par d’autres terres rares comme le samarium, l'yttrium ou le gadolinium. En particulier, le projet se focalisera sur l'étude de leur comportement en corrosion en milieu fortement alcalin. Le comportement calendaire et en cyclage de ces matériaux sera analysé et l'influence du magnésium sur la corrosion de tels systèmes sera étudié. Les produits de corrosion seront identifiés conjointement par des techniques de caractérisation morphologique, élémentaire et structurale.
In this work we investigate the effect of Gd and Co substitutions on the electrochemical and electronic properties of La1.5Mg0.5Ni7 alloy. Two series of La1.5−xGdxMg0.5Ni7 (x = 0.0, 0.25, 1.0) and La1.5Mg0.5Ni7−yCoy (y = 0.0, 0.5, 1.5) alloys are produced using mechanical alloying technique. The X-ray diffraction indicates multi-phase character of the samples with majority of hexagonal Ce2Ni7-type and rhombohedral Gd2Co7-type structures of (La,Mg)2Ni7 phase. Partial substitutions of La by Gd or Ni by Co in La1.5Mg0.5Ni7 phase result in increase of cycle stability of the metal hydride (MHx) electrodes. All considered alloys reach the maximum discharge capacity after three charging-discharging cycles. Two optimal compositions, in respect of electrochemical properties, are subsequently investigated by the X-ray photoelectron spectroscopy (XPS). The experimental analysis of the valence band is further extended by the density functional theory (DFT) calculations. We also discuss the effects of alloying and site preference of dopants on the position of the van Hove-type singularity as observed in the electronic densities of states (DOS) in proximity of the Fermi level.
In this review article, the fundamentals of electrochemical reactions involving metal hydrides are explained, followed by a report of recent progress in hydrogen storage alloys for electrochemical applications. The status of various alloy systems, including AB(5), AB(2), A(2)B(7)-type, Ti-Ni-based, Mg-Ni-based, BCC, and Zr-Ni-based metal hydride alloys, for their most important electrochemical application, the nickel metal hydride battery, is summarized. Other electrochemical applications, such as Ni-hydrogen, fuel cell, Li-ion battery, air-metal hydride, and hybrid battery systems, also have been mentioned.
Fe-Ti alloys were prepared by applying a pulsed electric current through compacted mixtures of iron, manganese and titanium oxide (with carbon) or titanium hydride (without carbon). After ball milling the mixture into a fine powder, the mixture was heated up to 1373–1573 K in a carbon mold by applying a pulsed electric current, and the temperature was maintained for 3–10 min. When TiO2 was used as a starting material, TiC was formed. Fe was alloyed into FeTi and Fe2Ti, with Ti also observed. When the C content was lowered to 8.136 wt%, the remaining C content after pulsed current application decreased to 4.64 wt%. When using TiH2 as a starting material, Fe was alloyed into FeTi and Fe2Ti, and Ti, Mn, Fe, and FeMn2 were also observed. For a Fe-Ti alloy prepared using titanium hydride as a starting material, hydrogen content vs. absorption time curves were obtained at various numbers of cycles and temperatures.
