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Multiphase Magnesium Rare Earth Nickel Hydrogen Storage Alloy and Its Application

A hydrogen storage alloy, nickel-based technology, applied in the field of hydrogen storage materials, can solve the problems of mismatched expansion ratio, unsatisfactory cycle performance, and increased alloy cost, and achieve good activity performance, good cycle stability, and ease of internal stress. Effect

Active Publication Date: 2017-11-14
HENAN POLYTECHNIC UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] China Invention Patent Application No. 200910163893.0 discloses a La-Mg-Ni negative electrode hydrogen storage material for Ni-MH batteries with ultra-low self-discharge and long-term storage performance, and its atomic ratio composition is La 0.65-x- y Nd x Dy y Ce 0.1 Mg 0.25 Ni 3.27 Al 0.13 , where 0.1≤x≤0.3, 0.01≤y≤0.05, the La-Mg-Ni type negative electrode hydrogen storage material is a compound with a multiphase structure, and its phase composition is mainly composed of two structures of A with different space groups 5 B 19 type compounds together, one of which is the space group P6 3 / mmc's Pr 5 co 19 structure, the other is Ce with space group R-3m 5 co 19 structure compound, the ratio of the two compounds is about 6:4, and there is also a small amount of Ce 2 Ni 7 and PuNi 3 type structure compound, the La-Mg-Ni type negative electrode hydrogen storage material can be used as a negative electrode material to prepare nickel-metal hydride batteries with ultra-low self-discharge and long-term storage performance. Ce 5 co 19 The phase ratio is difficult to control, and the maximum discharge capacity of the alloy is not ideal
The inventive product substitutes Ag, Sr, Ge, Au, etc. for B-side elements, and optimizes the alloy composition and annealing process, and adjusts the AB in the product 5 Phase and A 2 B 7 Compared with the value, the discharge capacity and cycle life of the hydrogen storage alloy are improved, and its self-discharge and low-temperature performance are improved. The disadvantages are: Ag, Sr, Ge, Au and other precious metals increase the cost of the alloy, which is not conducive to industrialization, and AB 5 Phase and A 2 B 7 During the charging process, the expansion ratio does not match, and the alloy is easy to pulverize, resulting in poor cycle stability
According to the analysis, the heating and heat preservation process plays a certain role in improving the uniformity of the phase structure of the hydrogen storage alloy, while the rapid cooling process plays a crucial role in improving the comprehensive performance of the hydrogen storage alloy. The disadvantage is that although the alloy has a high Discharge capacity, but cycle performance is not ideal
[0006] The above-mentioned patents disclose the elemental composition and preparation method of the rare earth-magnesium-nickel hydrogen storage alloy, but how to control the specific multiphase structure of the alloy, and the influence of the alloy phase composition and phase abundance on the hydrogen storage performance of the alloy No report

Method used

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  • Multiphase Magnesium Rare Earth Nickel Hydrogen Storage Alloy and Its Application
  • Multiphase Magnesium Rare Earth Nickel Hydrogen Storage Alloy and Its Application
  • Multiphase Magnesium Rare Earth Nickel Hydrogen Storage Alloy and Its Application

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Effect test

Embodiment 1

[0036] According to the designed chemical composition formula La 4 MgNi 17 Carry out batching, consider the loss of Mg, Mg excess 15wt%, take the La, Mg and Ni metal that purity is 99.9%, adopt medium-frequency induction melting of argon protection to prepare alloy, the alloy obtained is heat treated at 950 ℃ under argon protection, when When the temperature is lower than 500°C, the heating rate is 5°C / min, and then heated to 950°C at a heating rate of 2°C / min, and kept for 24 hours. The above-mentioned heat-treated alloy is naturally cooled in a protective atmosphere. Samples were subjected to X-ray analysis and Rietica software was used for refinement.

[0037] To measure the electrochemical performance of the alloy, the sample used for the test is the internal sample of the block alloy. The above-mentioned hydrogen storage alloy is mechanically pulverized, sieved with a sieve, and 0.15 grams of 200-400 mesh alloy powder and 0.75 grams of carbonyl nickel powder are taken. A...

Embodiment 2

[0042] Embodiment 2: chemical composition formula is La 3 SmMgNi 17.5 , the preparation method is the same as in Example 1.

[0043] Such as figure 1 Shown, the alloy La prepared in embodiment 2 3 SmMgNi 17.5 Middle A 5 B 19 Phase abundance is 8.34%, A 2 B 7 The phase abundance is 91.66%.

[0044] Such as figure 2 As shown, the La-Mg-Ni alloy prepared in Example 2 has good activation performance, and the maximum discharge capacity is 410.10mAh / g.

[0045] Such as image 3 Shown, the La-Mg-Ni series alloy that embodiment 2 prepares has the characteristic of high power, HRD 1500 (High-rate discharge performance at a discharge current density of 1500 mA / g) was 58.45%.

[0046] Such as Figure 4 Shown, the cycle stability of the La-Mg-Ni series alloy prepared in embodiment 2 is very good, S 200 (The capacity retention rate at 200 cycles of charge and discharge) was 95.00%, and the charge retention rate CR(36h)=93.2%.

Embodiment 3

[0047] Embodiment 3: chemical composition formula is La 4 MgNi 16.5 Co, the sample was kept at 900° C. for 24 hours after it came out of the furnace, and the rest were the same as in Example 1.

[0048] Such as figure 1 Shown, the alloy La prepared in embodiment 3 4 MgNi 16.5 A in Co 5 B 19 Phase abundance is 6.78%, A 2 B 7 The phase abundance is 93.22%.

[0049] Such as figure 2 As shown, the La-Mg-Ni alloy prepared in Example 3 has good activation performance, and the maximum discharge capacity is 412.48mAh / g.

[0050] Such as image 3 Shown, the La-Mg-Ni system A prepared in embodiment 3 2 B 7 type two-phase alloys are characterized by high power, HRD 1500 (High-rate discharge performance at a discharge current density of 1500 mA / g) was 60.10%.

[0051] Such as Figure 4 Shown, the cycle stability of the La-Mg-Ni series alloy prepared in embodiment 3 is very good, S 200 (The capacity retention rate at 200 cycles of charge and discharge) was 95.71%, and the ...

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Abstract

The invention discloses a multi-phase magnesium rare earth nickel based hydrogen storage alloy and an application thereof. The double-phase hydrogen storage alloy disclosed by the invention is combined by a phase A2B7 and a phase A5B19, is liable to activate, is high in discharge capacity and high in cycling stability. The composition of the alloy is La(4-x)RExMgNi(y-z)Bz, wherein RE is one or two elements of La, Ce, Pr, Nd, Gd, Sm and Y; B is one element of Cu, Al, Mn, Fe, Zn, Sn and Si; x is greater than or equal to 0 and smaller than or equal to 2, y is greater than or equal to 16 and smaller than or equal to 18, and z is greater than or equal to 0 and smaller than or equal to 5. When used as a negative electrode material of a nickel-hydrogen battery, the alloy disclosed by the invention has the characteristics of being liable to activate, high in capacity and good in cycling stability, and has a capacity retention ratio greater than 90% while cycling 1C charging / discharging by 200 weeks. And moreover, the alloy is low in cost, a preparation method is simple, and large-scale industrial production is easily realized.

Description

technical field [0001] The invention relates to the field of hydrogen storage materials, and in particular provides an A 2 B 7 (2H, 3R) and A 5 B 19 (2H, 3R) phase hydrogen storage alloys and their applications. Background technique [0002] Actively developing hydrogen storage materials with high specific capacity, low self-discharge, and long life, and developing high-capacity, high-stability hydrogen storage alloys for electric vehicles have always been one of the important topics in the research of new materials. In the secondary battery market, although lithium-ion batteries have developed rapidly in recent years, nickel / metal hydride (Ni / MH) batteries still occupy a large market share, and even have broad potential in some applications. market. In the development of Ni / MH batteries, the use and progress of anode materials has been one of the most anticipated key technologies. The La-Mg-Ni-based alloy with a special super-stacking structure developed at the beginn...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/38C22C1/02C22C29/00
CPCC22C1/02C22C29/00H01M4/383Y02E60/10
Inventor 刘宝忠范燕平陈强尚显光张宝庆
Owner HENAN POLYTECHNIC UNIV
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