MAGNESIUM-BASED SOLID HYDROGEN STORAGE MATERIAL WITH LIQUID PHASE REGULATION FUNCTION AND PREPARATION METHOD THEREOF

Abstract

A magnesium-based solid hydrogen storage material with liquid phase regulation function and a preparation method thereof and an application thereof in an all-solid-state battery are provided, belonging to the technical field of new energy. The magnesium-based solid hydrogen storage material with the liquid phase regulation function includes following raw materials in percentage by mass: 95% of magnesium hydride and 5% of lithium borohydride. Lithium borohydride as an ionic conductor is dispersed on a surface and matrix of magnesium hydride, which provides channels for the rapid hydrogen storage of the magnesium hydride-based materials.

Claims

1. A magnesium-based solid hydrogen storage material with a liquid phase regulation function, comprising following raw materials in percentage by mass: 95% of magnesium hydride and 5% of lithium borohydride.

2. A preparation method of the magnesium-based solid hydrogen storage material with a liquid phase regulation function according to claim 1, comprising following steps: mixing raw materials in an inert gas atmosphere according to the mass percentage, and performing ball milling to obtain the magnesium-based solid hydrogen storage material.

3. The preparation method of the magnesium-based solid hydrogen storage material with a liquid phase regulation function according to claim 2, wherein a ball-to-material ratio for the ball milling is 40.1.

4. The preparation method of the magnesium-based solid hydrogen storage material with the liquid phase regulation function according to claim 2, wherein a number of times of the ball milling is 20, and the duration of each ball milling is 30 minutes.

5. The preparation method of the magnesium-based solid hydrogen storage material with a liquid phase regulation function according to claim 2, wherein a diameter of a steel ball used in the ball milling is 5-7 millimeters; and a rotational speed of the ball milling is 400 revolutions per minute.

6. An application of the magnesium-based solid hydrogen storage material with a liquid phase regulation function according to claim 1 in preparing a hydrogen storage material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to explain the embodiments of the present application or the technical scheme in the prior art more clearly, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings may be obtained according to these drawings without creative work for ordinary people in the field.

[0024] FIG. 1 is a flow chart of preparing a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system according to embodiment 1 of the present application.

[0025] FIG. 2 is the X-ray diffraction (XRD) spectrum of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system before and after cycling prepared in embodiment 1 of the present application.

[0026] FIG. 3(a) is transmission electron microscope (TEM) of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application.

[0027] FIG. 3(b) is a fast fourier transform image of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application.

[0028] FIG. 3(c) is a lattice image of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application.

[0029] FIG. 3(d) is a fast fourier transform image of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application.

[0030] FIG. 3(e) is a lattice image of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application.

[0031] FIG. 4(a) is fourier-transform infrared spectrometer (FTIR) of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application.

[0032] FIG. 4(b) is an X-ray photoelectron spectroscopy (XPS) of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application.

[0033] FIG. 5 is scanning electron microscope SEM) images of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system before and after cycling prepared in embodiment 1 of the present application and corresponding elemental site labeling images, where Before represents before cycling and After represents after cycling.

[0034] FIG. 6 is a curve of isothermal hydrogen absorption of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system at different temperature gradients prepared in embodiment) of the present application.

[0035] FIG. 7 is a curve of isothermal hydrogen absorption of pure MgH.sub.2 at different temperature gradients.

[0036] FIG. 8(a) is an isothermal hydrogen absorption curve of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system at 300? C. for first six kinetics cycles prepared in embodiment 1 of the present application.

[0037] FIG. 8(b) is an isothermal hydrogen desorption curve of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system at 300? C. for first six kinetics cycles prepared in embodiment 1 of the present application.

[0038] FIG. 9(a) shows the isothermal hydrogen absorption curve of pure MgH.sub.2 in first six kinetics cycles at 300? C.

[0039] FIG. 9(b) shows the isothermal hydrogen desorption curve of pure MgH.sub.2 in first six kinetics cycles at 300? C.

[0040] FIG. 10(a) is an isothermal hydrogen desorption curve of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application, pure MgH.sub.2 and Li.sub.2B.sub.12H.sub.12/MgH.sub.2 hydrogen storage materials at 300? C. for a sixth kinetics cycle.

[0041] FIG. 10(b) is an isothermal hydrogen absorption curve of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application, pure MgH.sub.2 and Li.sub.2B.sub.12H.sub.12/MgH.sub.2 hydrogen storage materials at 300? C. for a sixth kinetics cycle.

[0042] FIG. 11(a) is temperature-rising hydrogen desorption curves of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application, pure MgH.sub.2 and MgH.sub.2 hydrogen storage materials.

[0043] FIG. 11(b) is corresponding derivative curves of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application, pure MgH.sub.2 and MgH.sub.2 hydrogen storage materials.

[0044] FIG. 12 is a high-temperature confocal micrograph of a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application, in which hydrogen is desorbed by liquid phase under high-temperature desorption.

[0045] FIG. 13 is an impedance diagram of batteries prepared by using a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application and pure MgH.sub.2.

[0046] FIG. 14 is a diagram showing an ionic conductivity performance of the batteries prepared by using a LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in Embodiment 1 of the present application, pure MgH.sub.2 and pure LiBH.sub.4

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] A number of exemplary embodiments of the present application will now be described in detail, and this detailed description should not be considered as a limitation of the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.

[0048] It should be understood that the terminology described in the present application is only for describing specific embodiments and is not used to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. The intermediate value within any stated value or stated range and every smaller range between any other stated value or intermediate value within the stated range are also included in the present application. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0049] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the field to which this application relates. Although the present application only describes the preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and materials related to the documents. In case of conflict with any incorporated document, the contents of this specification shall prevail.

[0050] It is obvious to those skilled in the field that many improvements and changes may be made to the specific embodiments of the present application without departing from the scope or spirit of the present application. Other embodiments will be obvious to the skilled person from the description of the application. The specification and embodiments of this application are only exemplary.

[0051] The terms comprising, including, having and containing used in this article are all open terms, which means including but not limited to.

Embodiment 1

[0052] Preparation method of magnesium-based solid hydrogen storage material with a liquid phase regulation function includes following steps:

[0053] 950 milligram (mg) of MgH.sub.2 powder and 50 mg of LiBH.sub.4 powder in a glove box filled with argon are weighed, and the MgH.sub.2 powder and the LiBH.sub.4 powder are put into a stainless-steel ball mill for ball milling (QM-3SP2 planetary ball mill). The technological parameters of the ball milling are as follows: ?(O.sub.2)<0.1 parts per million (ppm), ?(H.sub.2O)<0.1 ppm, a ball-to-material ratio of 40:1, steel ball diameter of 5-7 millimeter, and the rotational speed of 400 rpm, 30 min for each time of ball milling, an interval of each time of ball milling of 2 min. After ball milling, magnesium-based solid hydrogen storage material (LiBH.sub.4/MgH.sub.2 composite hydrogen storage system) is obtained. The preparation flow chart is shown in FIG. 1.

[0054] The X-ray diffraction (XRD) spectrum of LiBH.sub.4/MgH.sub.2 composite hydrogen storage system before and after cycling prepared in embodiment 1 of the present application is shown in FIG. 2, in which pure MgH.sub.2 is taken as the control. Before cycling (LiBH.sub.4-doped MgH.sub.2) refers to the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system without the hydrogen absorption and desorption process, and after cycling (cycled LiBH.sub.4-doped MgH.sub.2) refers to the LiBH.sub.4-doped MgH.sub.2 composite hydrogen storage system after one cycle of hydrogen absorption and desorption. See FIG. 3(a), FIG. 3(b), and FIG. 3 (e) for TEM diagram, Fourier transform diagram and lattice image. The FTIR diagram and XPS spectrum are shown in FIG. 4(a) and FIG. 4(b), in which (a) is the FTIR diagram and (b) is the XPS spectrum.

[0055] The LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in this example is subjected to one cycle of hydrogen absorption and hydrogen desorption, and the SEM images of the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system before and after the cycle and the corresponding elemental site labeling images. The results are shown in FIG. 5, where Before is before cycling and After is after cycling.

[0056] As can be seen from FIG. 1, FIG. 2, FIG. 3(a), FIG. 3(b), FIG. 4(a) and FIG. 4(b) and FIG. 5, LiBH.sub.4 is uniformly dispersed on the surface of MgH.sub.2, forming a banded structure convenient for H-transfer. LiBH.sub.4 exists stably as nanocrystalline or amorphousness during ball milling and cycling, and there is no decomposition and reaction to form a new phase before and after kinetics cycling. By observing the morphological evolution and element distribution of MgH.sub.2 before and after cycling, it is found that the particle distribution is uniform (1-2 microns (?m) before and after cycling) and the morphology is similar, and the corresponding elements are also uniform, with the average size of 1-2 ?m before and after cycling, which shows that the uniform distribution of LiBH.sub.4 inhibits the growth of Mg grains.

[0057] 0.15 gram (g) LiBH.sub.4/MgH.sub.2 composite hydrogen storage system is weighed in a glove box filled with argon, put into a sample chamber, and then the sealed sample chamber is evacuated and put into a resistance furnace for heating. The process parameters are: under vacuum, the temperature is raised by 5? C./min to the target temperature of 300? C., and the hydrogen pressure of 5 megapascal (MPa) is maintained during the temperature raising process to inhibit hydrogen storage and hydrogen desorption. It is found that when the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system is heated for 40 min, the mass percentage of desorbed hydrogen is 6.7 wt % (percentage by weight).

Comparative Example 1

[0058] Li.sub.2B.sub.12H.sub.12/MgH.sub.2 hydrogen storage material is prepared as follows;

[0059] 950 mg of MgH.sub.2 powder and 50 mg of Li.sub.2B.sub.12H.sub.12 powder are weighed in the glove box filled with argon, and put into a stainless-steel ball mill for ball milling (QM-3SP2 planetary ball mill). The technological parameters of ball milling are as follows: ?(O.sub.2)<0.1 ppm, ?(H.sub.2O)<0.1 ppm, the ball-to-material ration of 40:1, the diameter of steel ball of 5-7 mm, the rotational speed of 400 rpm, ball milling of 20 times, 30 min for each ball milling, interval of each ball milling of 2 min. The Li.sub.2B.sub.12H.sub.12/MgH.sub.2 hydrogen storage material is obtained after ball milling is completed.

[0060] In the glove box filled with argon, 0.15 g Li.sub.2B.sub.12H.sub.12/MgH.sub.2 hydrogen storage material is weighed and put into a sample chamber, and then the sealed sample chamber is vacuumized and put into a resistance furnace for heating. The process parameters are: temperature is raised by 5? C./min under vacuum to the target temperature of 300? C., and the hydrogen pressure of 5 MPa is maintained during the heating process to inhibit hydrogen storage and hydrogen desorption. It is found that when the Li.sub.2B.sub.12H.sub.12/MgH.sub.2 hydrogen storage material is heated for 40 min, the mass percentage of desorbed hydrogen is 1.5 wt %.

Comparative Example 2

[0061] MgH.sub.2 hydrogen storage material is prepared as follows;

[0062] 1000 mg of MgH.sub.2 powder is weighted in the glove box filled with argon and put into a stainless-steel ball mill tank for ball milling (QM-3SP2 planetary ball mill). The technological parameters of ball milling are as follows: ?(O.sub.2)<0.1 ppm, ?(H.sub.2O)<0.1 ppm, the ball-to-material ratio of 40:1, the diameter of steel ball is 5-7 mm, and the rotational speed of 400 rpm, ball milling of 20 times, 30 min for each ball milling, interval of each ball milling of 2 min. The MgH.sub.2 hydrogen storage material is obtained after ball milling is completed.

[0063] In a glove box filled with argon, 0.15 g MgH.sub.2 hydrogen storage material is weighed and put into a sample chamber, and then the sealed sample chamber is vacuumized and put into a resistance furnace for heating. The process parameters are: under vacuum, the temperature is raised by 5? C./min to the target temperature of 300? C., and the hydrogen pressure of 5 MPa is maintained during the heating process to inhibit hydrogen storage and hydrogen desorption. It is found that when MgH.sub.2 hydrogen storage material is heated for 40 min, the mass percentage of desorbed hydrogen is 0.3 wt %.

Effect Example 1

[0064] A curve of isothermal hydrogen absorption of LiBH.sub.4/MgH.sub.2 composite hydrogen storage system at different temperature gradients prepared in embodiment) of the present application is determined, with results shown in FIG. 6. A curve of isothermal hydrogen absorption of pure MgH.sub.2 at different temperature gradients is determined, with results shown in FIG. 7.

[0065] As can be seen from FIG. 6 and FIG. 7, both the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application and pure MgH.sub.2 have remarkable hydrogen absorption performance at 300? C. The LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application absorbs 6.5 wt % of hydrogen within 15 min, while the pure MgH.sub.2 in comparative example 1 absorbs 6.5 wt % of hydrogen after 40 min.

Effect Example 2

[0066] An isothermal hydrogen absorption curve of LiBH.sub.4/MgH.sub.2 composite hydrogen storage system at 300? C. for first six kinetics cycles prepared in embodiment 1 of the present application is determined, with results shown in FIG. 8(a). An isothermal hydrogen desorption curve of LiBH.sub.4/MgH.sub.2 composite hydrogen storage system at 300? C. for first six kinetics cycles prepared in embodiment 1 of the present application is determined, with results shown in FIG. 8(b).

[0067] The isothermal hydrogen absorption curve of pure MgH.sub.2 in first six kinetics cycles at 300? C. is determined with results shown in FIG. 9(a). The isothermal hydrogen desorption curve of pure MgH.sub.2 in first six kinetics cycles at 300? C., with results shown in FIG. 9(b).

[0068] An isothermal hydrogen desorption curve of LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application, pure MgH.sub.2 and Li.sub.2B.sub.12H.sub.12 hydrogen storage materials at 300? C. for the sixth kinetics cycle is determined, with results shown in FIG. 10(a).

[0069] An isothermal hydrogen absorption curve of LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application, pure MgH.sub.2 and Li.sub.2B.sub.12H.sub.12/MgH.sub.2 hydrogen storage materials (comparative example 1) at 300? C. for a sixth kinetics cycle is determined, with results shown in FIG. 10(b).

[0070] It can be seen from FIG. 8(a), FIG. 8(b), FIG. 9(a), FIG. 9(b), FIG. 10(a), FIG. 10(b) that after the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 and pure MgH.sub.2 are tested at 300? C. for six cycles of hydrogen absorption/desorption respectively, the hydrogen absorption capacity of pure MgH.sub.2 reaches 2.5 wt % within 10 min and the hydrogen desorption capacity of pure MgH.sub.2 reaches 0.7 wt % in the first cycle. However, the hydrogen absorption capacity of the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application reaches 6.7 wt % within 10 min and the hydrogen desorption capacity of the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system reaches 6.8 wt % within 40 min in the first cycle, which significantly improves the kinetics performance.

Effect Example 3

[0071] The temperature-rising hydrogen desorption performances of LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application, pure MgH.sub.2 and MgH.sub.2 hydrogen storage material (comparative example 2) is determined, with results shown in FIG. 11(a) and FIG. 11(b). FIG. 11(a) shows temperature-rising hydrogen desorption curves. FIG. 11(b) shows corresponding derivative curves.

[0072] In FIG. 11(a) and FIG. 11(b), MgH.sub.2 is pure MgH.sub.2, milled MgH.sub.2 (10 h) is MgH.sub.2 hydrogen storage material, and MgH.sub.2+5 wt % LiBH.sub.4 is LiBH.sub.4/MgH.sub.2 composite hydrogen storage system.

[0073] As can be seen from FIG. 11(a) and FIG. 11(b), the peak dehydrogenation temperature of the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared by the application is 340? C., the peak dehydrogenation temperature of the MgH hydrogen storage material is 360? C., and the peak dehydrogenation temperature of the pure MgH.sub.2 is 440? C.

Effect Example 4

[0074] The microstructure of the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application was measured at high temperature, and the results are shown in FIG. 12 (high temperature confocal micrograph).

[0075] As can be seen from FIG. 12, LiBH.sub.4 in the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application presents a liquid phase at high temperature, so that hydrogen is precipitated from the liquid borohydride phase in the form of bubbles, and compared with the solid phase with low relative migration energy, hydrogen moves rapidly in the liquid phase, thus improving the hydrogen desorption rate, and at the same time, the introduction of LiBH.sub.4 may provide more diffusion paths as a channel for diffusion.

Effect Example 5

[0076] The LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in Embodiment 1 of the present application and pure MgH.sub.2 are respectively prepared as positive electrode materials for all-solid-state batteries, and the impedance performance of the batteries is determined. The results are shown in FIG. 13, in which Pure MgH.sub.2 is pure MgH.sub.2 and LiBH.sub.4-doped MgH.sub.2 is the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in Embodiment 1 of the present application.

[0077] The LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in Embodiment 1 of the present application, pure MgH.sub.2 and pure LiBH.sub.4 are respectively prepared as positive electrode materials for all-solid-state batteries, and the ionic conductivity of the batteries is determined. The results are shown in FIG. 14. In FIG. 14, Pure LiBH.sub.4 is pure LiBH.sub.4, 5 wt % LiBH.sub.4-doped MgH.sub.2 is the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in Embodiment 1 of the present application, and Pure MgH.sub.2 is pure MgH.sub.2.

[0078] The preparation method of positive electrode materials of all-solid-state batteries is as follows:

[0079] 120 mg of the above materials are weighed in a glove box filled with argon gas respectively and pressed for 5 min under the pressure of 7 MPa to obtain the positive electrode materials of all-solid-state batteries, and the button-type all-solid-state batteries are assembled in the glove box filled with argon gas, with metal lithium sheets as the negative electrode materials and LiBH.sub.4 as the electrolyte.

[0080] As can be seen from FIG. 13, compared with the battery prepared by pure MgH.sub.2, the battery prepared by the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared by the embodiment 1 of the present application has a reduced impedance from 8.39?10.sup.4? (ohm) to 2.42?10.sup.4?, and the resistance of the battery prepared by the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared by the embodiment 1 of the present application gradually decreases with the increase of temperature, and the corresponding resistance value is decreased to 1.05?10.sup.5? from 4?10.sup.6? at 55? C.

[0081] With the introduction of LiBH.sub.4, MgH.sub.2 is changed to a conductor from an insulator. As can be seen from FIG. 14, the ionic conductivity of the LiBH.sub.4/MgH.sub.2 composite hydrogen storage system prepared in embodiment 1 of the present application is 3.2?10.sup.?7 S/cm (siemens per centimeter).

[0082] The above-mentioned embodiments only describe the preferred mode of the application, and do not limit the scope of the application. Under the premise of not departing from the design spirit of the application, various modifications and improvements made by ordinary technicians in the field to the technical scheme of the application shall fall within the protection scope determined by the claims of the application.