CN105274374A - A kind of preparation method of Mg2Ni0.9Co0.1H4 based hydrogen storage material - Google Patents

Abstract

The invention discloses a preparation method of a Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material, belonging to the technical field of hydrogen storage materials. In this method, Ni(Co) solid solution powder is obtained by wet ball milling; according to the composition of master alloy Mg ₂ Ni _1-x Co _x (x=0.1～0.2), a certain amount of solid solution and Mg powder are vacuum sintered to obtain master alloy, master alloy The chemical composition range of the alloy is: the atomic percentage of Mg is 65-70%, Ni+Co accounts for the remaining percentage of the alloy, and the atomic percentage of Co in Ni+Co is 10-20%; then the sintered alloy is hydrogenated in a hydrogenation furnace The target hydrogen storage material is obtained, which is composed of 85-90wt% Mg ₂ Ni _0.9 Co _0.1 H ₄ matrix phase, 6-7wt% MgH ₂ and 4-8wt% MgNi ₃ Co phase. The hydrogen storage material has high hydrogen storage capacity (greater than 3.5 wt%), low initial hydrogen desorption temperature (220° C.) and excellent hydrogen desorption kinetics. The preparation method of the invention has the remarkable characteristics of simple process, high efficiency, high yield and no pollution.

Description

A kind of preparation method of Mg2Ni0.9Co0.1H4 based hydrogen storage material

technical field

The invention relates to the technical field of hydrogen storage materials, in particular to a method for preparing a Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material.

Background technique

Among metallic hydrogen storage materials, metallic Mg is considered to be the most promising hydrogen storage material due to its low price, low weight density, and high hydrogen storage capacity (7.6wt% by weight). However, the slow hydrogen absorption and desorption kinetics and high thermodynamic stability limit its further application. People introduce transition metals (TM) into Mg and form Mg-TM-H hydrides by changing the phase structure, which can improve the thermodynamic and kinetic properties of magnesium-based alloys for hydrogen storage. This pathway includes two cases: one is the preparation of stable intermetallic compound Mg ₂ Ni by common methods such as smelting and sintering, and then direct hydrogenation to form Mg ₂ NiH ₄ hydride; the other is that although there is no stable Mg-TM (TM=Co, Fe, Cr, Mn, etc.) intermetallic compounds, but hydrides such as Mg ₂ FeH ₆ , Mg ₂ CoH ₅ , Mg ₃ CrH _～6 and Mg ₃ MnH _～6 can be prepared by high pressure reactive ball milling. Since the latter type of hydrides are generally prepared by unconventional means (requiring hydrogen pressure up to ~GPa and long-time reactive ball milling), their large-scale application is actually very difficult.

Mg ₂ NiH ₄ has two different structure hydrides, namely high temperature cubic structure (LT) and low temperature monoclinic structure (HT). In order to further improve the hydrogen storage performance of Mg ₂ NiH ₄ , people try to develop a new system of Mg-Ni-Co-H quaternary materials. Nanocrystalline and amorphous Mg ₂ Ni _1-x Co _x (x=0-0.4) alloys can be prepared by melt blowing; although nanocrystalline and amorphous can improve the hydrogen storage performance of the alloy, Co cannot be combined with other The beneficial effect of Co on the hydrogen storage performance has not been effectively exerted [YH Zhang, BW Li, HP Ren, et al., Journal of Alloys and Compounds, 509(2011), 2808.]. In addition, meltblown equipment has a large investment and low yield, which is not suitable for the needs of industrial production. Recently, people have discovered two new hydrides, Mg ₂ Ni _0.5 Co _0.5 H _4.4 and Mg ₂ Ni _0.9 Co _0.1 H ₄ , whose structures are completely different from LT and HT type Mg ₂ NiH ₄ . Among them, Mg, Ni, and Co powders were ball-milled for a long time under a hydrogen pressure greater than 7 MPa and a milling speed of 400-800 rpm to obtain Mg ₂ Ni _0.5 Co _0.5 H _4.4 hydride [Yu.Verbovytskyy, J. Zhang, F. Cuevas, et al., Journal of Alloys and Compounds, http://dx.doi.org/10.1016/j.jallcom.2014.12092.]. Although a small amount of Mg ₂ Ni _0.9 Co _0.1 H ₄ hydride was found in the hydrogenated samples of Mg ₆₀ Ni ₃₀ La _10-x Co _x (x=2,4) alloy prepared by the two-step method of rapid quenching and mechanical alloying[ Lu Peng, Guilin: Guilin University of Electronic Science and Technology, 2014.] However, from the perspective of large-scale hydrogen storage applications of Mg ₂ Ni _0.9 Co _0.1 H ₄ hydrides, new hydrogen storage based on Mg ₂ Ni _0.9 Co _0.1 H ₄ Further breakthroughs are required in materials and new preparation methods.

Contents of the invention

In order to overcome the deficiencies of the prior art, the present invention provides a method for preparing Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage materials with simple process, high efficiency, high yield and no pollution.

The method for preparing Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage materials in the present invention specifically includes the following steps:

(1) Co powder and Ni powder are weighed according to the ratio that the atomic percentage of Co in Ni+Co is 10% to 20%, and the remainder is Ni;

(2) Pour Co powder and Ni powder into a stainless steel ball mill tank, add stainless steel balls according to the ball-to-material ratio of 20:1, pour industrial alcohol to submerge the powder and stainless steel balls, seal the tank lid, and place the stainless steel ball mill tank in Wet ball milling in ball mill;

(3) After the ball milling is finished, dry and remove industrial alcohol in an oven to obtain Ni(Co) solid solution powder;

(4) Weigh the Mg powder with 65-70% atomic percentage and the Ni(Co) solid solution powder with the remaining atomic percentage for ball milling and mixing, and the ball-to-material ratio is 20:1 during ball milling and mixing;

(5) placing the alloy powder mixed in step (4) in a stainless steel sintering boat, and vacuum sintering in a vacuum sintering furnace to obtain Mg ₂ Ni _1-x Co _x sintered alloy, wherein x=0.1～0.2;

(6) The sintered Mg ₂ Ni _1-x Co _x alloy was hydrogenated in a hydrogenation furnace to obtain a Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material.

In the step (1), the particle size of Co powder and Ni powder is not lower than 200 mesh, and the purity is not lower than 99.5%.

In the step (2), the time for wet ball milling is 30-50 hours, and the rotational speed of the ball mill is 150-250 rpm.

In the step (3), the industrial alcohol is dried in an oven at 30-50° C. for 0.5-1 hour to remove it.

In the step (4), the Mg powder has a particle size of not less than 200 mesh and a purity of not less than 99.5%;

In the step (4), the rotational speed of the ball mill is 100-300 rpm, and the ball milling time is 0.5-1.5 h.

In the step (5), the vacuum sintering is carried out in a vacuum sintering furnace at 550° C., and the vacuum sintering time is 15-25 hours.

In the step (6), the hydrogen pressure in the hydrogenation furnace is 3-5 MPa, the temperature is 300° C., and the hydrogenation time is 2 hours.

The Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material obtained by the preparation method of the present invention is composed of 85-90 wt % Mg ₂ Ni _0.9 Co _0.1 H ₄ matrix phase, 6-7 wt % MgH ₂ and 4-8 wt % MgNi ₃ Co phase composition.

Compared with prior art, the beneficial effect of the present invention is:

1. This invention successfully prepared a Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material system for the first time. The Mg ₂ Ni _0.9 Co _0.1 H ₄ matrix phase content in the material is greater than 85wt%, so that the material has a high Hydrogen storage capacity (greater than 3.5 wt%).

2. The master alloy is prepared by sintering Mg powder and Ni(Co) solid solution of wet ball milling. The master alloy contains a small amount of MgNi ₃ Co phase, which is a new phase that has not been discovered (reported), and this new phase has The characteristics of transition metals have a good catalytic effect on the hydrogen storage performance of the alloy. Combined with the high activity of the Mg ₂ Ni _0.9 Co _0.1 H ₄ matrix itself, the material system has a low initial hydrogen desorption temperature (220 ° C) and excellent Hydrogen release kinetics.

3. The preparation method has the remarkable characteristics of simple process, high efficiency, high yield and no pollution.

Description of drawings

Fig. 1 is the X-ray diffraction pattern of Ni(Co) solid solution powder prepared in the present invention.

Fig. 2 is an X-ray diffraction pattern of the Mg ₂ Ni _1-x Co _x (x=0.1-0.2) sintered alloy prepared in the present invention.

Fig. 3 is an X-ray diffraction pattern of the Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material prepared in the present invention.

Fig. 4 is the hydrogen desorption curve of the Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material prepared by the present invention.

detailed description

The present invention is described in detail below in conjunction with specific examples, but the present invention is not limited to the following examples.

Example 1

According to the composition of Ni _0.9 Co _0.1 , Ni powder (particle size: 200 mesh, purity 99.5%) and Co powder (particle size: 200 mesh, purity 99.5%) were weighed, 50 grams of Ni powder and Co powder in total. Put the weighed Ni powder and Co powder into a stainless steel ball mill tank, add stainless steel balls according to the ball-to-material ratio of 20:1, then pour industrial alcohol to submerge the balls and materials, and seal the ball mill tank cover. The ball mill jar was placed in a ball mill for wet ball milling for 40 hours, and the rotational speed of the ball mill was 200 rpm. After ball milling, dry in an oven at 40°C for 0.5h to remove industrial alcohol, and obtain Ni _0.9 Cu _0.1 solid solution powder with high chemical stability. The powder is composed of a single Ni(Co) solid solution phase (see Figure 1: Ni(Co ) solid solution powder X-ray diffraction pattern). According to the composition of Mg ₂ Ni _0.9 Co _0.1 , 80 grams of Mg powder (particle size 200 mesh, purity 99.5%) and Ni _0.9 Co _0.1 solid solution powder were weighed respectively, and put into a stainless steel ball mill jar for ball milling and mixing. The ball-to-material ratio is 20:1 during ball milling, the rotational speed of the ball mill is 200rpm, and the ball milling time is 0.5h. The mixed alloy powder was placed in a stainless steel sintering boat, and vacuum sintered in a vacuum sintering furnace at 550°C for 20 hours to obtain the Mg ₂ Ni _0.9 Co _0.1 alloy. The sintered alloy was composed of Mg ₂ Ni _0.9 Co _0.1 and a small amount of Mg and MgNi ₃ Co phases ( See Figure 2: X-ray diffraction pattern of Mg ₂ Ni _1-x Co _x (x=0.1-0.2) sintered alloy). Finally, the sintered alloy was placed in a hydrogenation furnace, hydrogenated at 3MPa hydrogen pressure and 300°C for 2h to obtain a Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material; calculated by X-ray diffraction Rietveld method, it was composed of 90wt% Mg ₂ Ni _0.9 Co _0.1 H ₄ matrix phase, 6 wt% MgH ₂ and 4 wt% MgNi ₃ Co phase composition (see Figure 3: X-ray diffraction pattern of Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage materials). The Mg ₂ Ni _0.9 Co _0.1 H ₄ based hydrogen storage material starts to release hydrogen from 220°C, and the hydrogen release is basically completed at 320°C, with a hydrogen release rate of 3.72wt% (Fig. 4: Mg ₂ Ni _0.9 Co _0.1 H ₄ based hydrogen storage material Heating hydrogen desorption curve). The phase composition of the hydrogen-discharged sample is the same as that of the master alloy, indicating that the prepared hydrogen storage material has good reversibility.

Example 2

According to the composition of Ni _0.85 Co _0.15 , Ni powder (200 mesh particle size, 99.5% purity) and Co powder (200 mesh particle size, 99.5% purity) were weighed respectively, 50 grams of Ni powder and Co powder in total. Put the weighed Ni powder and Co powder into a stainless steel ball mill tank, add stainless steel balls according to the ball-to-material ratio of 20:1, then pour industrial alcohol to submerge the balls and materials, and seal the ball mill tank cover. The ball mill pot was placed in a ball mill for wet ball milling for 40 hours, and the rotational speed of the ball mill was 200 rpm. After ball milling, dry in an oven at 40°C for 0.5h to remove industrial alcohol, and obtain Ni _0.9 Cu _0.1 solid solution powder with high chemical stability. The powder is composed of a single Ni(Co) solid solution phase (see Figure 1: Ni(Co ) solid solution powder X-ray diffraction pattern). According to the composition of Mg ₂ Ni _0.85 Co _0.15 , 80 grams of Mg powder (particle size 200 mesh, purity 99.5%) and Ni _0.85 Co _0.15 solid solution powder were weighed respectively, and put into a stainless steel ball mill jar for ball milling and mixing. The ball-to-material ratio is 20:1 during ball milling, the rotational speed of the ball mill is 200rpm, and the ball milling time is 0.5h. The mixed alloy powder was placed in a stainless steel sintering boat, and vacuum sintered in a vacuum sintering furnace at 550°C for 20 hours to obtain a Mg ₂ Ni _0.85 Co _0.15 alloy. The sintered alloy was composed of Mg ₂ Ni _0.9 Co _0.1 and a small amount of Mg and MgNi ₃ Co phases ( See Figure 2: X-ray diffraction pattern of Mg ₂ Ni _1-x Co _x (x=0.1-0.2) sintered alloy). Finally, the sintered alloy was placed in a hydrogenation furnace, hydrogenated at 3MPa hydrogen pressure and 300°C for 2h to obtain a Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material; calculated by X-ray diffraction Rietveld method, it was composed of 88wt% Mg ₂ Ni _0.9 Co _0.1 H ₄ matrix phase, 6 wt% MgH ₂ and 6 wt% MgNi ₃ Co phase composition (see Figure 3: X-ray diffraction pattern of Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material). The Mg ₂ Ni _0.9 Co _0.1 H ₄ based hydrogen storage material starts to release hydrogen from 220°C, and the hydrogen release is basically completed at 320°C, with a hydrogen release rate of 3.65wt% (Fig. 4: Mg ₂ Ni _0.9 Co _0.1 H ₄ based hydrogen storage material Heating hydrogen desorption curve). The phase composition of the hydrogen-discharged sample is consistent with that of the master alloy, indicating that the prepared hydrogen storage material has good reversibility.

Example 3

According to the composition of Ni _0.8 Co _0.2 , Ni powder (200 mesh particle size, 99.5% purity) and Co powder (200 mesh particle size, 99.5% purity) were weighed respectively, 50 grams of Ni powder and Co powder in total. Put the weighed Ni powder and Co powder into a stainless steel ball mill tank, add stainless steel balls according to the ball-to-material ratio of 20:1, then pour industrial alcohol to submerge the balls and materials, and seal the ball mill tank cover. The ball mill pot was placed in a ball mill for wet ball milling for 40 hours, and the rotational speed of the ball mill was 200 rpm. After ball milling, dry in an oven at 40°C for 0.5h to remove industrial alcohol and obtain Ni _0.8 Cu _0.2 solid solution powder with high chemical stability. The powder is composed of a single Ni(Co) solid solution phase (see Figure 1: Ni(Co ) solid solution powder X-ray diffraction pattern). According to the composition of Mg ₂ Ni _0.8 Co _0.2 , 80 grams of Mg powder (particle size 200 mesh, purity 99.5%) and Ni _0.8 Co _0.2 solid solution powder were weighed respectively, and put into a stainless steel ball mill jar for ball milling and mixing. The ball-to-material ratio is 20:1 during ball milling, the rotational speed of the ball mill is 200rpm, and the ball milling time is 0.5h. The mixed alloy powder was placed in a stainless steel sintering boat, and vacuum sintered in a vacuum sintering furnace at 550°C for 20 hours to obtain a Mg ₂ Ni _0.8 Co _0.2 alloy. The sintered alloy was composed of Mg ₂ Ni _0.9 Co _0.1 and a small amount of Mg and MgNi ₃ Co phases ( See Figure 2: X-ray diffraction pattern of Mg ₂ Ni _1-x Co _x (x=0.1-0.2) sintered alloy). Finally, the sintered alloy was placed in a hydrogenation furnace, hydrogenated at 3MPa hydrogen pressure and 300°C for 2h to obtain a Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material; calculated by X-ray diffraction Rietveld method, it was composed of 85wt% Mg ₂ Ni _0.9 Co _0.1 H ₄ matrix phase, 7 wt% MgH ₂ and 8 wt% MgNi ₃ Co phase composition (see Figure 3: X-ray diffraction pattern of Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage materials). The Mg ₂ Ni _0.9 Co _0.1 H ₄ based hydrogen storage material starts to release hydrogen at 220°C, and the hydrogen release is basically completed at 320°C, with a hydrogen release rate of 3.56wt% (Fig. 4: Mg ₂ Ni _0.9 Co _0.1 H ₄ based hydrogen storage material Heating hydrogen desorption curve). The phase composition of the hydrogen-discharged sample is consistent with that of the master alloy, indicating that the prepared hydrogen storage material has good reversibility.

Claims (9)

1. A preparation method of Mg ₂ Ni _0.9 Co _0.1 H ₄ based hydrogen storage material, characterized in that, comprising the steps: (1) Co powder and Ni powder are weighed according to the ratio that the atomic percentage of Co in Ni+Co is 10% to 20%, and the remainder is Ni; (2) Pour Co powder and Ni powder into a stainless steel ball mill tank, add stainless steel balls according to the ball-to-material ratio of 20:1, pour industrial alcohol to submerge the powder and stainless steel balls, seal the tank lid, and place the stainless steel ball mill tank in Wet ball milling in ball mill; (3) After the ball milling is finished, dry and remove industrial alcohol in an oven to obtain Ni(Co) solid solution powder; (4) Weigh the Mg powder with 65-70% atomic percentage and the Ni(Co) solid solution powder with the remaining atomic percentage for ball milling and mixing, and the ball-to-material ratio is 20:1 during ball milling and mixing; (5) placing the alloy powder mixed in step (4) in a stainless steel sintering boat, and vacuum sintering in a vacuum sintering furnace to obtain Mg ₂ Ni _1-x Co _x sintered alloy, wherein x=0.1～0.2; (6) The sintered Mg ₂ Ni _1-x Co _x alloy was hydrogenated in a hydrogenation furnace to obtain a Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material. 2. The preparation method of Mg ₂ Ni _0.9 Co _0.1 H ₄ base hydrogen storage material as claimed in claim 1, it is characterized in that, in step (1), the particle size of Co powder and Ni powder is not less than 200 orders, and purity is not less than 200 meshes. Less than 99.5%. 3. The preparation method of Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material as claimed in claim 1, characterized in that, in step (2), the wet ball milling time is 30-50 hours, and the ball mill speed is 150- 250rpm. 4. The method for preparing Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material according to claim 1, characterized in that, in step (3), industrial alcohol is dried in an oven at 30-50°C for 0.5-1h to remove . 5. The preparation method of Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material as claimed in claim 1, characterized in that, in step (4), the particle size of Mg powder is not less than 200 mesh, and the purity is not less than 99.5 %. 6 . The preparation method of Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material according to claim 1 , characterized in that, in step (4), the rotational speed of the ball mill is 100-300 rpm, and the ball milling time is 0.5-1.5 h. 7. The preparation method of Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material as claimed in claim 1, characterized in that, in step (5), vacuum sintering is carried out in a vacuum sintering furnace at 550°C, and the vacuum sintering time is 15～25h. 8. The method for preparing Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material according to claim 1, characterized in that in step (6), the hydrogen pressure in the hydrogenation furnace is 3-5 MPa, and the temperature is 300°C , The hydrogenation time is 2h. 9. A Mg ₂ Ni _0.9 Co _0.1 H ₄ -based hydrogen storage material obtained by the preparation method according to any one of claims 1-8.