Li prepared by mechanical ball milling3AlH6Material and method thereof
阅读说明：本技术 一种通过机械球磨制备的Li3AlH6材料及其方法 (Li prepared by mechanical ball milling3AlH6Material and method thereof ) 是由 李芸 何俊 张玉贤 陈立新 于 2020-12-03 设计创作，主要内容包括：本发明公开了一种通过机械球磨制备的Li-3AlH-6材料及其方法,制备方法具体如下：将LiH和LiAlH-4在惰性气氛下混合均匀并研磨粉碎,得到混合样品；将混合样品放入装有研磨球的球磨罐中,将球磨罐抽真空后并充入惰性气体；将充入惰性气体的球磨罐装入球磨机中,进行间歇式球磨至少50h,得到Li-3AlH-6材料。本发明通过研究合成Li-3AlH-6过程中的原料配比、球料比、球磨气氛等参数,尤其是强调了球磨中的冷却周期,从而实现了能够通过简单的机械球磨方法合成高纯度的Li-3AlH-6材料。本发明的方法操作简单,仅需要使用常规的球磨机,配合相应球磨参数和方法,即可实现高纯度Li-3AlH-6材料的制备。(The invention discloses Li prepared by mechanical ball milling 3 AlH 6 The material and the method thereof have the following specific preparation method: mixing LiH and LiAlH 4 Uniformly mixing and grinding the mixture in an inert atmosphere to obtain a mixed sample; putting the mixed sample into a ball milling tank filled with grinding balls, vacuumizing the ball milling tank and filling inert gas into the ball milling tank; filling the ball mill tank filled with inert gas into a ball mill, and performing intermittent ball milling for at least 50h to obtain Li 3 AlH 6 A material. The invention synthesizes Li by research 3 AlH 6 The parameters of the raw material proportion, the ball-material ratio, the ball-milling atmosphere and the like in the process particularly emphasize the cooling period in the ball milling, thereby realizing the synthesis of high-purity Li by a simple mechanical ball milling method 3 AlH 6 A material. The method of the invention has simple operation, only needs to use the conventional ball mill, and is matched with the corresponding ball milling parameters and methodCan realize high-purity Li 3 AlH 6 And (4) preparing the material.)
1. Preparation of Li by mechanical ball milling3AlH6The method of the material is characterized by comprising the following steps:
s1: mixing LiH and LiAlH4Uniformly mixing and grinding the mixture in an inert atmosphere to obtain a mixed sample;
s2: putting the mixed sample into a ball milling tank filled with grinding balls, vacuumizing the ball milling tank and filling inert gas into the ball milling tank;
s3: filling the ball mill tank filled with inert gas into a ball mill, and performing intermittent ball milling for at least 50h to obtain Li3AlH6A material.
2. Preparation of Li by mechanical ball milling according to claim 13AlH6A method for producing a material, characterized in that in S1, LiH and LiAlH4The mixing molar ratio of (1) to (2).
3. Preparation of Li by mechanical ball milling according to claim 13AlH6The method for preparing the material is characterized in that in the S1, the inert atmosphere is argon.
4. Preparation of Li by mechanical ball milling according to claim 13AlH6A method for producing a material, characterized in that in S1, LiH and LiAlH are added4Mix in a glove box and grind with a mortar for 10 minutes.
5. Preparation of Li by mechanical ball milling according to claim 13AlH6The method for preparing the material is characterized in that in the step S2, the grinding balls are made of stainless steel; the grinding balls comprise first grinding balls with the diameter of 10mm and second grinding balls with the diameter of 5mm, and the number ratio of the first grinding balls to the second grinding balls in the ball-milling tank is 1: 3.
6. Preparation of Li by mechanical ball milling according to claim 13AlH6The method for preparing the material is characterized in that in the S2, the mass ratio of the mixed sample to the grinding balls is 1: 25.
7. Preparation of Li by mechanical ball milling according to claim 13AlH6The method for preparing the material is characterized in that in the step S2, inert gas is filled into a ball milling tank, so that the ball milling tank has 5 atmospheres of pressure and 99.999 mass percent of argon.
8. Preparation of Li by mechanical ball milling according to claim 13AlH6The method for preparing the material is characterized in that in the S3, the ball mill is a planetary ball mill, and the rotating speed is 300 rpm.
9. Preparation of Li by mechanical ball milling according to claim 13AlH6The method for preparing the material is characterized in that in S3, the batch ball milling is specifically as follows:
and stopping the ball mill for 6min every 24min of operation of the ball mill, and performing ball milling on the mixed sample by adopting an alternate operation mode.
10. Li prepared by the method of any one of claims 1 to 93AlH6A material.
Technical Field
The invention belongs to the field of material preparation, and particularly relates to Li prepared by mechanical ball milling3AlH6Materials and methods therefor.
Background
Lithium aluminum hydride (Li)3AlH6) The hydrogen storage tank can be used for industries such as hydrogen storage and the like. Compared with the traditional energy, the hydrogen energy has the outstanding advantages of high energy density, renewability, environmental friendliness and the like, and is an ideal green energy. In recent years, the novel metal complex hydride becomes a new research hotspot of hydrogen storage materials at home and abroad due to the high weight and volume hydrogen storage density.
Wherein Li3AlH6The theoretical hydrogen storage amount of the material reaches 11 percent, and the material is a hydrogen storage functional material with great potential. Li3AlH6Is LiAlH4The intermediate product of the thermal decomposition has active and easy chemical properties and is difficult to synthesize, and the finished product is difficult to purchase through the market.
Therefore, it is highly desirable to provide a method for simply synthesizing high-purity Li3AlH6A method of making a material.
Disclosure of Invention
The object of the present invention is to overcome the drawbacks of the prior art and to provide a Li prepared by mechanical ball milling3AlH6Materials and methods therefor.
The invention adopts the following specific technical scheme:
the invention provides a method for preparing Li by mechanical ball milling3AlH6The method of the material comprises the following specific steps:
s1: mixing LiH and LiAlH4Uniformly mixing and grinding the mixture in an inert atmosphere to obtain a mixed sample;
s2: putting the mixed sample into a ball milling tank filled with grinding balls, vacuumizing the ball milling tank and filling inert gas into the ball milling tank;
s3: filling the ball mill tank filled with inert gas into a ball mill, and performing intermittent ball milling for at least 50h to obtain Li3AlH6A material.
Preferably, in S1, LiH and LiAlH4The mixing molar ratio of (1) to (2).
Preferably, in S1, the inert gas atmosphere is argon.
Preferably, in S1, LiH and LiAlH are used4Mix in a glove box and grind with a mortar for 10 minutes.
Preferably, in S2, the grinding balls are made of stainless steel; the grinding balls comprise first grinding balls with the diameter of 10mm and second grinding balls with the diameter of 5mm, and the number ratio of the first grinding balls to the second grinding balls in the ball-milling tank is 1: 3.
Preferably, in S2, the mass ratio of the mixed sample to the grinding balls is 1: 25.
Preferably, in S2, in S2, the ball milling tank is filled with an inert gas so that the ball milling tank has argon gas at a concentration of 99.999% by mass and at 5 atmospheres.
Preferably, in S3, the ball mill is a planetary ball mill, and the rotation speed is 300 rpm.
Preferably, in S3, the batch ball mill is specifically as follows:
and stopping the ball mill for 6min every 24min of operation of the ball mill, and performing ball milling on the mixed sample by adopting an alternate operation mode.
It is another object of the present invention to provide Li prepared by any one of the above-mentioned methods3AlH6A material.
Compared with the prior art, the invention has the following beneficial effects:
the invention synthesizes Li by adjusting3AlH6The parameters such as raw material proportion, ball-to-material ratio, ball-milling atmosphere and the like in the process especially research the influence on Li3AlH6The intermittent ball milling and ball milling time of the final synthesis effect of the material can realize the synthesis of high-purity Li by a simple mechanical ball milling method3AlH6A material. Li obtained by the process3AlH6The particle size is 1-3 mu m, and the powder material is in dispersion distribution. The method of the invention has simple operation, only needs to use the conventional ball mill and is matched with the corresponding ball milling referenceThe method can realize high-purity micro-nano Li3AlH6And (4) preparing the material.
Drawings
FIG. 1 shows pure LiH samples (a) and pure LiAlH obtained in example 24Sample (b) and 2LiH-LiAlH4XRD pattern of the synthesized product (c) after ball milling for 20 h;
FIG. 2 is an XRD pattern of the synthesized product of example 2 at different ball milling times;
FIG. 3 is the pure LiAlH of example 34Sample (a) and 2LiH-LiAlH4Infrared IR spectrum of the synthesized product (b) after ball milling for 50 h.
Detailed Description
The invention will be further elucidated and described with reference to the drawings and the detailed description. The technical features of the embodiments of the present invention can be combined correspondingly without mutual conflict.
Example 1
Due to Li required in the experiment3AlH6The powder is very active and is difficult to buy finished products on the market, and Li is prepared by a mechanical ball milling method in the embodiment3AlH6The material is as follows:
firstly, pure LiH and pure LiAlH4Mixing in a 2:1 mixing molar ratio in a glove box with an argon atmosphere, and grinding with a mortar for 10 minutes to obtain LiH and LiAlH4Fully crushing and uniformly mixing to obtain a mixed sample.
And then putting the mixed sample into a ball milling tank filled with grinding balls, wherein the mass ratio of the mixed sample to the grinding balls is 1: 25. The ball milling tank is vacuumized and then filled with high-purity argon, so that the ball milling tank has argon with the concentration of 99.999 percent by mass and the pressure of 5 atmospheres. And taking out the glove box after screwing the ball, and fixing the glove box on a ball mill to start ball milling.
In the implementation, the grinding balls are made of stainless steel, in order to enable grinding to be more sufficient, the grinding balls adopt two specifications, namely a first grinding ball with the diameter of 10mm and a second grinding ball with the diameter of 5mm, and the first grinding ball and the second grinding ball are added into a ball grinding tank according to the quantity ratio of 1: 3.
Finally, filling the ball mill pot filled with inert gas into a planetary ball mill, and carrying out intermittent ball milling for at least 50h to obtain Li3AlH6A material. The intermittent ball milling means that: and stopping the ball mill for 6min every 24min of operation of the ball mill, namely, one period is 30min, and performing ball milling on the mixed sample by adopting a periodic operation mode of alternate operation.
In the ball milling process, the ball mill is not suitable to adopt too high rotating speed so as to avoid Li caused by the temperature rise of the ball milling tank3AlH6And (4) decomposing the product. In this embodiment, the rotation speed of the ball mill is 300rpm, which is ensured in the case of LiH and LiAlH4Fully react to obtain Li3AlH6While avoiding the formation of Li3AlH6And (5) further decomposing.
Comparative example
This comparative example prepared Li in the same manner as in example 13AlH6Synthetic materials, but after the ball mill pot was filled in a planetary ball mill, continuous ball milling was used for at least 50 hours instead of batch ball milling. As a result, it was found that high temperatures were generated during the continuous ball milling process, and the high temperatures resulted in the synthesis of Li3AlH6The material is decomposed at high temperature, which affects the purity of the final product.
Therefore, the invention adopts the running mode of the batch ball milling to avoid the high temperature generated in the ball milling process to ensure that the synthesized Li is not easy to be oxidized3AlH6Pyrolysis, so after 24min of operation, 6min is stopped to cool the device, avoiding Li3AlH6Is lost by decomposition.
Example 2
In order to further explore the ball milling time for the prepared Li3AlH6On the basis of the preparation method of example 1, in this example, after 20 hours of ball milling, each 10 hours of ball milling, the ball milling jar was taken down, and the sample adhered to the wall of the ball milling jar was scraped off in the glove box, i.e., XRD analysis was performed on the samples with the ball milling time periods of 20 hours, 30 hours, 40 hours, and 50 hours, and the results were as follows:
as shown in FIG. 1, the sample is pure LiH, pure LiAlH4Sample and 2LiH-LiAlH4After ball milling for 20h, a sample (i.e. Li) was synthesized3AlH6) XRD pattern of (a). As can be seen from the figure, LiH samples and LiAlH4The XRD pattern of the sample only has a single LiH phase and LiAlH4Phase, it is demonstrated that the purity of the sample is very high and that it is not oxidized and does not absorb water. 2LiH-LiAlH4In a synthetic sample after ball milling for 20 hours, most diffraction peaks are LiAlH4A few very weak peaks are characteristic peaks of LiH, diffraction peaks of some newly generated phases are near 22 degrees, 32 degrees and 39 degrees, and the characteristic peaks are Li compared with standard cards3AlH6Characteristic peak of (2).
The experimental results show that LiH and LiAlH are obtained by ball milling4Can produce Li3AlH6The sample has the defects that the ball milling time of 20h is too short, and the synthesis reaction is incomplete.
In order to obtain Li with higher purity3AlH6And (5) continuing to prolong the ball milling time of the sample, similarly taking out the sample every 10 hours, tamping the sample, and taking a small amount of sample for XRD analysis. The XRD patterns of the synthesized products at different ball milling times are shown in fig. 2. As can be seen from the figure, most of diffraction peaks of the synthesized product after ball milling for 30h are Li3AlH6Wherein the doublet located in the vicinity of 22 DEG and 23 DEG is considered to be Li3AlH6The unique peak shape of the phase indicates that the synthesis reaction has been substantially completed. However, LiH phase and LiAlH still exist near 26 degrees, 45 degrees and 66 degrees4And (4) phase(s). From pure LiAlH4The sample can be found in an XRD pattern of LiAlH4The "three strong peaks" of the sample are located around 23 °, 26 ° and 27 °. The synthesized product after 40h of ball milling still has a protrusion diffraction peak near 27 degrees, and a LiH phase diffraction peak near 46 degrees, so the synthesis reaction is still incomplete. All the synthetic products after ball milling for 50h are Li3AlH6Diffraction characteristic peak of phase, LiAlH4The "three strong peaks" of the sample disappeared and it was considered that the synthesis had proceeded to completion. And the ball milling time is prolonged on the basis of ball milling for 50h, so that the properties of the obtained synthetic sample are not changed, and in order to save cost and time, the ball milling time is selected to be 50h as the optimal ball milling time.
Example 3
In this example, pure LiAlH was used4Sample (a) and 2LiH-LiAlH in example 24The infrared IR spectrum analysis of the synthesized product (b) after ball milling for 50h was performed, and the result is shown in fig. 3.
In LiAlH4In the sample, the stretching vibration of the Al-H bond is 1757cm－1And 1615cm－1The bending vibration of the Li-Al-H bond is located at 900cm－1And 830cm－1. In Li3AlH6In the sample, the stretching vibration of the Al-H bond was 1386cm－1And 1276cm－1The bending vibration of the Li-Al-H bond was located at 1000cm－1、950cm－1And 850cm－1. Pure LiAlH in the figure4The infrared spectrum of the sample is consistent with the reported results; and in 2LiH-LiAlH4The synthesized product after ball milling for 50 hours is positioned at 1757cm－1And 1615cm－1The stretching vibration of Al-H bond(s) disappears. This example further demonstrates LiAlH4After the reaction is finished, the generated products are all Li3AlH6。
The method has simple operation, and can realize high-purity Li by only using a conventional ball mill and matching with corresponding ball milling parameters and method3AlH6And (4) preparing the material.
The above-described embodiments are merely preferred embodiments of the present invention, which should not be construed as limiting the invention. Various changes and modifications may be made by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present invention. Therefore, the technical scheme obtained by adopting the mode of equivalent replacement or equivalent transformation is within the protection scope of the invention.
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