Method for preparing lithium borohydride by means of solid-phase ball milling at room temperature

Abstract

A method for preparing lithium borohydride by means of room temperature solid phase ball milling, comprising the following steps: uniformly mixing a magnesium-containing reducing agent and a lithium metaborate-containing reducing material under a non-oxidizing atmosphere at room temperature, performing solid phase ball milling, isolating and purifying to obtain lithium borohydride. The method has the advantages of having a simple process, having a controllable and adjustable reaction procedure, having mild reaction conditions, energy consumption being low, costs being low, and output being high, while creating no pollution, being safe and cyclically using boron resources, having important practical significance.

Claims

1. A method for preparing lithium borohydride by means of solid-phase ball milling at room temperature, comprising the following steps: under room temperature and non-oxidizing atmosphere, solid-phase ball milling, separating, and purifying uniformly mixed magnesium-containing reducing agent and a lithium metaborate-based material to obtain the lithium borohydride (LiBH.sub.4); wherein the magnesium-containing reducing agent is one or more selected from the group consisting of magnesium, aluminum magnesium and calcium magnesium alloys; the lithium metaborate-based material is composed of both hydrous lithium metaborate and anhydrous lithium metaborate, or the lithium metaborate-based material is hydrous lithium metaborate; and the non-oxidizing atmosphere is an argon atmosphere or a mixed atmosphere of argon and hydrogen; the non-oxidizing atmosphere holds a pressure of 0-3 MPa.

2. The method of claim 1, wherein the lithium metaborate-based material is hydrous lithium metaborate; wherein the hydrous lithium metaborate comprises LiBO.sub.2.Math.2H.sub.2O, LiBO.sub.2.Math.8H.sub.2O or LiBO.sub.2.Math.1/2H.sub.2O.

3. The method of claim 1, wherein a mixing ratio of the magnesium-containing reducing agent to the lithium metaborate-based material is determined by:
(n.sub.1+1.5n.sub.2+n.sub.3):x=(1:1)˜(2.5:1) wherein n.sub.1≥0, n.sub.2≥0, n.sub.3≥0, wherein a mole number of magnesium is n.sub.1, a mole number of aluminum is n.sub.2, a mole number of calcium is n.sub.3 in the magnesium-containing reducing agent; wherein n.sub.1≥0, n.sub.2≥0, n.sub.3≥0; wherein x=2 or 4, wherein a mole number of oxygen is x in the lithium metaborate-based material.

4. The method of claim 1, wherein the ratio of ball-to-powder for the solid-phase ball milling is 10:1 to 70:1.

5. The method of claim 1, wherein the rotating speed for the solid-phase ball milling is 1000 to 1200 rpm, and the ball milling time is from 1 h to 30 h.

6. The method of claim 1, wherein the separating and purifying comprise dissolving the ball-milled mixtures in a solvent, filtering for removing insoluble residues, and evaporating the obtained clear filtrate under high vacuum; wherein the solvent is diethyl ether which is distilled over Na.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows FTIR spectra of the ball-milled mixtures of magnesium and lithium metaborate dihydrate in Embodiments 5 to 8 and Embodiment 10, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 5, b—Embodiment 6, c—Embodiment 7, d—Embodiment 8, e—Embodiment 10;

(2) FIG. 2 shows X-ray diffraction (XRD) patterns of lithium borohydride prepared in Embodiment 1 and the commercial lithium borohydride;

(3) FIG. 3 shows FTIR spectra of lithium borohydride purified in Embodiment 1;

(4) FIG. 4 shows FTIR spectra of the ball-milled mixtures of magnesium and lithium metaborate dihydrate in Embodiments 2 to 4, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 2, b—Embodiment 3, c—Embodiment 4;

(5) FIG. 5 shows FTIR spectra of the ball-milled mixtures of magnesium and lithium metaborate dihydrate in Embodiments 11 to 13, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 11, b—Embodiment 12, c—Embodiment 13;

(6) FIG. 6 shows FTIR spectra of the ball-milled mixtures of magnesium and lithium metaborate dihydrate in Embodiment 7 and Embodiments 14 to 15, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 14, b—Embodiment 7, c—Embodiment 15;

(7) FIG. 7 shows FTIR spectra of the ball-milled mixtures of magnesium and lithium metaborate dihydrate in Embodiment 3 and Embodiments 16 to 17, wherein, each curve corresponds to a corresponding embodiment, respectively: a—Embodiment 3, b—Embodiment 16, c—Embodiment 17;

(8) FIG. 8 shows FTIR spectra of the ball-milled mixtures of magnesium and lithium metaborate dihydrate in Embodiment 9, Embodiment 13 and Embodiment 18, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 18, b—Embodiment 9, c—Embodiment 13;

(9) FIG. 9 shows FTIR spectra of the ball-milled mixtures of magnesium and lithium metaborate dihydrate in Embodiments 19 to 21, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 19, b—Embodiment 20, c—Embodiment 21;

(10) FIG. 10 shows FTIR spectra of the ball-milled mixtures of magnesium and lithium metaborate dihydrate in Embodiments 22 to 24, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 22, b—Embodiment 23, c—Embodiment 24;

(11) FIG. 11 shows FTIR spectra of the ball-milled mixtures of magnesium and lithium metaborate dihydrate in Embodiments 25 to 27, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 25, b—Embodiment 26, c—Embodiment 27;

(12) FIG. 12 shows FTIR spectra of the ball-milled mixtures of magnesium and anhydrous lithium metaborate under H.sub.2 atmosphere in Embodiment 31 and FTIR spectra of the ball-milled mixture of aluminum magnesium and lithium metaborate dihydrate in Embodiment 32, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 32, b—Embodiment 31;

(13) FIG. 13 shows FTIR spectra of the ball-milled mixtures of magnesium silicide and calcium magnesium with lithium metaborate dihydrate in Embodiments 33 to 34, wherein, each curve refers to a corresponding embodiment, respectively: a—Embodiment 33, b—Embodiment 34.

DESCRIPTION OF THE EMBODIMENTS

(14) The technical proposal of the invention will be described in detail below in combination with specific embodiments and attached figures, and the protection scope and implementation of the invention are not limited thereto.

(15) In specific embodiments, the process of separation and purification is as below:

(16) In a glovebox filled with argon atmosphere, the ball-milled mixtures are dissolved and extracted with the distilled diethyl ether, and then filtered to remove the insoluble residues and a clear filtrate is acquired; the colatuie is evaporated under high vacuum to obtain high-purity lithium borohydride powder; finally the yield of regenerated LiBH.sub.4 was quantitatively determined by iodometric analysis.

(17) In specific embodiments, the target products prepared are mainly characterized over Fourier infrared spectrometer (FT-IR) or X-ray diffractometer (XRD).

Embodiment 1

(18) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(19) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C) under argon atmosphere, where the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the ball milling time is 20 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest;

(20) The ball-milled mixtures after ball milling process are dissolved and extracted with the distilled diethyl ether, and then filtered to remove the insoluble residues and a clear filtrate is acquired; the colatuie is evaporated under high vacuum to obtain a white powder; The XRD patterns of the obtained white powder and the commercial LiBH.sub.4 (95%) are shown in FIG. 2. It can be seen that the white powder is lithium borohydride with high purity, the yield of which is quantitatively determined to be 38.0% by iodometric analysis.

(21) The price of raw material Mg is about 2.2/kg (based on the market price of magnesium at about ¥14500/ton), thus the cost of raw materials for the production of 1 ton of lithium borohydride is about $33576; whereas the price of raw material lithium chloride is about $9.95/kg, and the price of sodium borohydride is about $20/kg in industrial application, the cost of raw materials for the production of 1 ton of lithium borohydride would be about $72138; The preparation cost in this embodiment is significantly decreased in terms of the price of raw materials.

Embodiment 2

(22) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(23) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(24) FTIR spectrum of the ball-milled mixtures is as shown in curve a of FIG. 4, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 in FTIR correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(25) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively determined to be 7.1% by iodometric analysis.

Embodiment 3

(26) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(27) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(28) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 4, consistent with curve a of FIG. 7. It can be seen from FIG. 4, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(29) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively determined to be 18.1% by iodometric analysis.

Embodiment 4

(30) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(31) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1100 rpm, and the time is 15 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(32) FTIR spectra of the ball-milled mixtures is as shown in curve c of FIG. 4, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(33) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 27.7% by iodometric analysis.

Embodiment 5

(34) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(35) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 30:1, the rotating speed is 1200 rpm, and the time is 1 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(36) FTIR spectra of the ball-milled mixtures is as shown in curve a of FIG. 1, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride; and these peaks are relatively weak, demonstrating that the reaction for the generation of lithium borohydride is going on.

Embodiment 6

(37) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(38) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 30:1, the rotating speed is 1200 rpm, and the time is 2.5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(39) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 1, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride; and these vibration peaks have been strengthened compared to that in Embodiment 5, indicating that the yield of lithium borohydride increases with the further prolonged ball milling time.

Embodiment 7

(40) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(41) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest. FTIR spectra of the ball-milled mixtures is as shown in curve c of FIG. 1, consistent with curve b of FIG. 6. It can be seen from curve c in FIG. 1 that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(42) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 9.8% by iodometric analysis.

Embodiment 8

(43) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(44) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1000 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(45) FTIR spectra of the ball-milled mixtures is as shown in curve d of FIG. 1, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(46) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 25.7% by iodometric analysis.

Embodiment 9

(47) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(48) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 30:1, the rotating speed is 1200 rpm, and the time is 15 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(49) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 8, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(50) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 30.0% by iodometric analysis.

Embodiment 10

(51) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(52) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 15 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(53) FTIR spectra of the ball-milled mixtures is as shown in curve e of FIG. 1, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(54) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 37.9% by iodometric analysis.

Embodiment 11

(55) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(56) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(57) FTIR spectra of the ball-milled mixtures is as shown in curve a of FIG. 5, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(58) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 5.8% by iodometric analysis.

Embodiment 12

(59) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(60) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(61) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 5, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(62) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 13.8% by iodometric analysis.

Embodiment 13

(63) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(64) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 15 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(65) FTIR spectra of the ball-milled mixtures is as shown in curve c of FIG. 5, consistent with curve c of FIG. 8. It can be seen from curve c of FIG. 5, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(66) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 12.7% by iodometric analysis.

Embodiment 14

(67) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(68) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 30:1, the rotating speed is 1200 rpm, and the time is 5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(69) FTIR spectra of the ball-milled mixture is as shown in curve a of FIG. 6, from which it can be seen that the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(70) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 3.8% by iodometric analysis.

Embodiment 15

(71) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(72) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 70:1, the rotating speed is 1200 rpm, and the time is 5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(73) FTIR spectra of the ball-milled mixtures is as shown in curve c of FIG. 6, from which it can be seen that the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(74) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 9.4% by iodometric analysis.

Embodiment 16

(75) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(76) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 70:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(77) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 7, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(78) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 25.6% by iodometric analysis.

Embodiment 17

(79) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(80) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 30:1, the rotating speed is 1000 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(81) FTIR spectra of the ball-milled mixtures is as shown in curve c of FIG. 7, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(82) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 11.4% by iodometric analysis.

Embodiment 18

(83) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(84) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, Mg and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 70:1, the rotating speed is 1200 rpm, and the time is 15 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(85) FTIR spectra of the ball-milled mixtures is as shown in curve a of FIG. 8, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(86) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 10.2% by iodometric analysis.

Embodiment 19

(87) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(88) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(89) FTIR spectra of the ball-milled mixtures is as shown in curve a of FIG. 9, from which it can be seen that the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(90) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 66.1% by iodometric analysis.

Embodiment 20

(91) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(92) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1100 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(93) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 9, from which it can be seen that the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(94) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 56.5% by iodometric analysis.

Embodiment 21

(95) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(96) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 15 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(97) FTIR spectra of the ball-milled mixtures is as shown in curve c of FIG. 9, from which it can be seen that the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(98) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 51.6% by iodometric analysis.

Embodiment 22

(99) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(100) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(101) FTIR spectra of the ball-milled mixtures is as shown in curve a of FIG. 10, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(102) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 56.7% by iodometric analysis.

Embodiment 23

(103) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(104) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(105) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 10, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(106) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 70.3% by iodometric analysis.

Embodiment 24

(107) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(108) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 4.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 15 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(109) FTIR spectra of the ball-milled mixtures is as shown in curve c of FIG. 10, from which it can be seen that, the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(110) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 62.4% by iodometric analysis.

Embodiment 25

(111) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(112) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(113) FTIR spectra of the ball-milled mixtures is as shown in curve a of FIG. 11, from which it can be seen that the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(114) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 71.0% by iodometric analysis.

Embodiment 26

(115) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(116) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(117) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 11, from which it can be seen that the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(118) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 76.5% by iodometric analysis.

Embodiment 27

(119) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(120) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 15 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(121) FTIR spectra of the ball-milled mixtures is as shown in curve c of FIG. 11, from which it can be seen that the peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(122) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 67.5% by iodometric analysis.

Embodiment 28

(123) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(124) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 5 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(125) It is demonstrated that there is lithium borohydride generated from the analysis on FTIR results of the ball-milled mixtures;

(126) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 74.6% by iodometric analysis.

Embodiment 29

(127) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(128) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(129) It is demonstrated that there is lithium borohydride generated from the analysis on FTIR results of the ball-milled mixtures;

(130) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 68.3% by iodometric analysis.

Embodiment 30

(131) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(132) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, MgH.sub.2 and LiBO.sub.2.Math.2H.sub.2O (at a molar ratio of 5.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 15 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(133) It is demonstrated that there is lithium borohydride generated from the analysis on FTIR results of the ball-milled mixtures;

(134) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 61.5% by iodometric analysis.

Embodiment 31

(135) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(136) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, magnesium and anhydrous lithium metaborate (at a molar ratio of 2:1) are mixed, loaded into a ventilated ball milling jar which is filled with 3 MPa of hydrogen after evacuation. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C) under H.sub.2 atmosphere, for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(137) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 12, from which it can be seen that the strong vibration peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(138) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 48.1% by iodometric analysis.

Embodiment 32

(139) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(140) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, magnesium aluminum alloy (Mg.sub.17Al.sub.12) and lithium metaborate dihydrate (at a molar ratio of 4:17) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(141) FTIR spectra of the ball-milled mixtures is as shown in curve a of FIG. 12, from which it can be seen that the vibration peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(142) The ball-milled mixtures are dissolved and extracted with diethyl ether, and filtered to gain a clear filtrate; the colatuie is evaporated under high vacuum to obtain a white powder, which is identified to be highly pure LiBH.sub.4 over XRD analysis, and the yield is quantitatively calculated to be 34.2% by iodometric analysis.

Embodiment 33

(143) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(144) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, magnesium silicide (Mg.sub.2Si) and lithium metaborate dihydrate (at a molar ratio of 2.5:1) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(145) FTIR spectra of the ball-milled mixtures is as shown in curve a of FIG. 13, from which it can be seen that the weak vibration peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

Embodiment 34

(146) Preparation of lithium borohydride through solid-phase ball milling at room temperature, the procedures of which are given below:

(147) At room temperature, in a glovebox filled with argon atmosphere of 0.1 MPa, calcium magnesium (CaMg.sub.2) and lithium metaborate dihydrate (at a molar ratio of 5:3) are mixed, loaded into a ball milling jar which can be well sealed. The ball milling process is then conducted on a high energy vibrational ball mill (QM-3C), for which the ratio of ball-to-powder is 50:1, the rotating speed is 1200 rpm, and the time is 10 h. The milling process is carried out by alternating 30 min of milling and 30 min of rest.

(148) FTIR spectra of the ball-milled mixtures is as shown in curve b of FIG. 13, from which it can be seen that the vibration peaks appeared at 2200 to 2400 cm.sup.−1 and 1125 cm.sup.−1 correspond to the vibration absorption peaks of B—H bond, demonstrating the generation of lithium borohydride.

(149) The aforementioned embodiments are preferred implementations of the invention, but the implementations of the invention are not limited to these embodiments. Any other changes, modifications, replacements, combinations, simplifications made to the invention without departing from its spirit and principle all should be considered as equivalent substitutions and comprised in the protection scope of the invention.