Study on AB2-type Ti-Mn-based hydrogen storage alloy for metal hydride hydrogen compressor Guo Xiumei, Wang Shumao, Liu Xiaopeng, Li Zhinian, Lu Fang, Hao Lei, Mi Jing, Jiang Lijun (Institute of Energy Materials and Technology, Beijing Research Institute of Nonferrous Metals, Beijing 100088, China) Zr-Mn-CrV-Fe series hydrogen compression materials, the effects of V-Fe, Mn/Cr ratio and Zr content on the hydrogen absorption and desorption platform characteristics and thermodynamic properties of the alloy were studied, and the excellent comprehensive hydrogen storage performance was optimized. Hydrogen compression material Mn.4Cr035V0.2Fe. 05 alloy. The alloy has a low hydrogen absorption and desorption platform pressure, a small pressure hysteresis and a flat platform characteristic, and the hydrogen evolution reaction has a large transformation. It is an alloy material with a high hydrogen compression ratio and can be used in an oil bath. A very high hydrogen pressurization is achieved by the action of the heat source medium.
With the rapid development of hydrogen-fueled fuel cells and electric vehicles, the research and construction of on-board hydrogen storage technology and hydrogen energy infrastructure has attracted widespread attention in various countries, but the traditional mechanical hydrogen compressor There are shortcomings such as large volume, heavy weight, high power consumption, high water consumption, low energy efficiency, etc., and it is difficult to meet the requirements of high-efficiency on-board hydrogen storage technology. The development of high-pressure and light-weight new hydrogen storage pressure vessels is an important trend in the international stage to solve high-efficiency on-board hydrogen storage. Metal hydride 1 has a low hydrogen absorption pressure at low temperature and a high hydrogen pressure at high temperature. This feature of metal hydride can be used to pressurize hydrogen instead of mechanical hydrogen compressor to achieve very high target hydrogen pressure. One technique is known as metal hydride hydrogen compression technology.
The key link in metal hydride hydrogen compression technology is the development of hydrogen compression materials. For metal hydride materials for hydrogen compressors, the following requirements are generally met: (1) large hydrogen storage capacity; (2) flat platform pressure; (3) small pressure hysteresis; (4) large hydride Produces heat, high compression ratio; (5) good kinetic performance; (6) long cycle life, good resistance to poisoning and aging. To this end, scientists from various countries have conducted extensive research work to find metal hydride hydrogen compression materials with excellent properties. Commonly used metal hydride hydrogen compression materials are divided into AB511-61 and AB26~9. For the entire AB5 type hydrogen compression material system, the pressure of the hydrogen absorption and desorption platform is low, and only a low hydrogen pressure can be achieved under mild pressure. Moreover, the AB5 type hydrogen compression material has a very small amount of hydrogen absorption at room temperature (1%), which is very disadvantageous for hydrogen compression materials. In contrast, the AB2 type Laves phase hydrogen compression alloy has a large amount of hydrogen absorption (8wt%), and the pressure range of the hydrogen absorption and desorption platform is also wide. It is possible to achieve a wide hydrogen pressurization range by selecting different systems.
A large amount, but its hydrogen release rate is very low, it is generally required to multi-alloy to increase its hydrogen release. In this study, the hydrogen storage alloys of Ti-Zi-Mn-Ci-V-Fe series were designed. The hydrogen absorption and desorption platform characteristics and thermodynamic properties were measured. The effects of different components on the hydrogen storage performance of the alloy were studied. A metal hydride hydrogen compression material with excellent properties. The alloy material can achieve higher hydrogen pressurization by chemical thermal compression under a lower hydrogen pressure of the raw material.
1. With the increase of Zi content in the alloy, the pressure of hydrogen absorption and desorption platform at room temperature decreases from 412 MPa and 205 MPa to 205 MPa and 112 MPa, respectively. The platform slope coefficient Sf decreases from 0 81 to 0.76. The degree of pressure hysteresis in the process is also reduced. The pressure hysteresis coefficient Hf decreases from 0 68 to 0.47. The hydrogen absorption capacity of the alloy increases with the increase of Zi content to the radius of H/fu=306.Zi atom (216A). It is slightly larger than Ti atom (20A). The addition of Zi atom increases the unit cell volume of the alloy, so that the hydrogen atom in the alloy can be hydrogen. The thermodynamic performance of the alloy is based on the pressure of the hydrogen release platform of the alloy at different temperatures. The van'tHoff curve is fitted to the curve by the "least squares method". The argon change AH ​​of the hydrogen evolution reaction of the alloy is calculated according to the slope of the fitted straight line. The hydrogen discharge platform pressure and the room temperature hydrogen absorption at 100 °C The ratio of platform pressure is defined as the hydrogen compression coefficient of the alloy, that is, the hydrogen evolution coefficient of the hydrogen evolution reaction of all alloys at 7310/Pa (293K) is IAH1 and the hydrogen compression coefficient at 100 °C are listed in Table 1. It can be seen from the table. , the addition of V-Fe alloy While the characteristics of the alloy platform are reduced, the hydrogen evolution reaction of the alloy is reduced, and the hydrogen compression coefficient Rp of the alloy is decreased. The increase of the Mn/Cr ratio makes the values ​​of the alloys IAH1 and Rp further decrease. The increase of Zr content in the alloy can greatly improve the IAHI and Rp values ​​of the alloy while improving the properties of the alloy. Among the alloys studied, Ti09ZrniMm4Cm35V02Fe005 has the largest dehydrogenation reaction enthalpy (IAH=27.64k (mol.1) ―1H2) and the maximum hydrogen compression coefficient (Rp=7 1), the hydrogen release pressure of the alloy at 130 ° C can reach 20 MPa and can produce 40 MPa hydrogen pressure at 167 ° C. Compare 4 alloy materials found , Titi95Z1.005Mn0sCrti95V (i2Fen05 alloy can achieve the highest pressure of the hydrogen release platform at the same temperature, the temperature required to reach the hydrogen pressure of 20MPa and 40MPa is only 79 ° C and 114 but the alloy is sucked at room temperature The pressure of the hydrogen release platform is relatively high, so the hydrogen of the raw material with high pressure (~ 10 MPa) is required to saturate the hydrogen absorption. The pressure of the hydrogen absorption platform of the 921-01 River 4035V02Fen05 alloy is lower at room temperature, and the hydrogen is 4 MPa. Under the hydrogen absorption to achieve saturation, and the alloy also shows better platform characteristics, is a good performance of hydrogen compression materials, the alloy to achieve hydrogen pressure of products above 20MPa requires the use of oil bath as a heat source medium.
4 Conclusions Hydrogen compression materials have been studied for the effects of V-Fe, Mn/Cr ratio and Zi element on hydrogen storage properties and thermodynamic properties of the alloy. The addition of V-Fe alloy increases the pressure of the hydrogen absorption and desorption platform of the alloy, and the platform characteristics are significantly improved. The increase of Mn/Cr ratio causes the platform pressure of the alloy to increase slightly, and the platform inclination and pressure hysteresis increase significantly. The increase of Zr content in the alloy greatly improves the overall hydrogen storage performance of the alloy. In the alloy series studied, Ti09Zm1Mm4Cr.35Va2Fe005 alloy is optimized. The alloy has a low hydrogen absorption and desorption platform pressure at room temperature, the platform area is relatively flat, the pressure hysteresis is also small, and its effective hydrogen storage capacity is large. Both the enthalpy change and the hydrogen compression coefficient of the hydrogen reaction are large. If the oil bath is used as the heat source medium, the 4 MPa raw material hydrogen gas can be compressed to 20 MPa or more.
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