Mono-nuclei cationized magnesium salt, preparation method and applications thereof

Abstract

The invention relates to a mono-nuclei cationized magnesium salt, a preparation method and applications thereof. The mono-nuclei cationized magnesium salt has a chemical formula of MgR.sub.nMX.sub.4-mY.sub.m, wherein R is a non-aqueous solvent molecule, M includes Al.sup.3+ and/or B.sup.3+, X and Y respectively include halide ion and halogenoid ion, n is any one integer selected in the range of 06, and m is any one integer selected in the range of 0-4. The mono-nuclei cationized magnesium salt provided by the invention has a simple structure and excellent electrochemical properties, and the preparation method thereof features low cost, integrated synthesis, accessible raw materials, simple preparation process, and simple scaled production. The provided mono-nuclei cationized magnesium salt is used as the electrolyte of the rechargeable batteries, the generated electrolyte solution has a high ionic conductivity, a high reversible magnesium deposition-dissolution efficiency, excellent circulating performance and a high anode oxidation deposition potential. For example, when the electrolyte solution is applied to the magnesium batteries, the initial discharging capacity of the batteries can reach over 700 mAh/g, and the cycle number is greater than 20.

Claims

1. An electrolyte solution, comprising: an electrolyte solvent comprising an non-aqueous solvent and an ionic liquid, and an electrolyte comprising a magnesium salt dissolved in the electrolyte solvent, wherein the magnesium salt is mono-nuclei cationized and has a chemical formula of MgR.sub.nMX.sub.4-mY.sub.m, wherein R is a non-aqueous solvent molecule selected from the group consisting of tetrahydrofuran, toluene, dioxane, pyridine, dimethyl sulfoxide, dimethyl formamide, N-methylimidazole, acetonitrile, glycol dimethyl ether, triethylene glycol dimethyl ether (TEGDME), and polyethylene glycol dimethyl ether; M includes at least one of Al.sup.3+or B.sup.3+; X and Y respectively comprise halide ions or halogenoid ions; wherein the halogenoid ions include CN.sup.or SCN.sup.; n is any one integer selected in the range of 0-6, and m is any one integer selected in the range of 0-4.

2. The electrolyte solution of claim 1, having an electrolyte concentration of 0.1-1.5 mol/L.

3. The electrolyte solution of claim 1, wherein the ionic liquid is selected from a group consisting of imidazole ionic liquids, pyrrolic ionic liquids, and piperidine ionic liquids and the non-aqueous solvent is selected from the group consisting of tetrahydrofuran, toluene, glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dioxane, pyridine, dimethyl sulfoxide, dimethyl formamide, N-methylimidazole, acetonitrile, and polyethylene glycol dimethyl ether.

4. A method of making a magnesium battery, the method comprising, assembling a magnesium battery using the electrolyte solution of claim 1, wherein the magnesium battery can be a disposable magnesium battery or a rechargeable magnesium battery.

5. The electrolyte solution of claim 1, wherein the ionic liquid is 1-methyl-(1-butyl) pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSl).

6. The electrolyte solution of claim 5, wherein the electrolyte solvent is PYR14TFSI/THF and the magnesium salt is [Mg(THF).sub.6] [AlCl.sub.4].sub.2.

7. The electrolyte solution of claim 1, wherein the magnesium salt is selected from the group consisting of [Mg(THF).sub.6][AlCl.sub.4].sub.2, [Mg(THF).sub.6][AlF.sub.4].sub.2, [Mg(THF).sub.6][AlClF.sub.3].sub.2, [Mg(THF).sub.6][BCl.sub.4].sub.2, [Mg(TEGDME).sub.2][AlCl.sub.4].sub.2, [Mg(toluene).sub.6][AlCl.sub.4].sub.2, [Mg(DMSO).sub.6][AlCl.sub.4].sub.2, and [Mg(DMSO).sub.6][AlF.sub.4].sub.2.

8. A method to synthesize an electrolyte solution that comprises an electrolyte solvent and an electrolyte, wherein the electrolyte comprises a magnesium salt having a chemical formula of MgR.sub.nMX.sub.4mY.sub.m, wherein R is a non-aqueous solvent molecule, selected from the group consisting of tetrahydrofuran, toluene, dioxane, pyridine, dimethyl sulfoxide, dimethyl formamide, N-methylimidazole, acetonitrile, glycol dimethyl ether, triethylene glycol dimethyl ether, and polyethylene glycol dimethyl ether; M includes at least one of Al.sup.3+or B.sup.3+; X and Y respectively comprise halide ions or halogenoid ions; wherein the halogenoid ions include CN.sup.or SCN.sup.; n is any one integer selected in the range of 0-6, and m is any one integer selected in the range of 0-4, the method comprising: reacting a Lewis acid containing Mg.sup.2+with a Lewis base containing at least one of Al.sup.3+or B.sup.3+in an ionic liquid to generate an intermediate solution, and adding a non-aqueous solvent into the intermediate solution to form the electrolyte solution, wherein the magnesium salt is mono-mucleic cationized and the electrolyte solvent comprises the ionic liquid and the non-aqueous solvent.

9. The method of claim 8, wherein the Lewis acid and the Lewis base are reacted in a temperature of 30-200 C. and a reaction time of 3-48h.

10. The method of claim 8, wherein the Lewis acid includes inorganic magnesium salts MgX.sub.2, and X is selected from a group consisting of halide ions or halogenoid ions; the Lewis base includes at least one of inorganic aluminum salts AlY.sub.3 or boron salts BY.sub.3, and Y is selected from a group consisting of halide ions or halogenoid ions; and the halogenoid ions include CN.sup.or SCN.sup..

11. The method of claim 8, wherein the ionic liquid consists of at least one of imidazole ionic liquids, pyrrolic ionic liquids, or piperidine ionic liquids.

12. The synthesis method of claim 8, wherein the non-aqueous solvent is selected from a group consisting of tetrahydrofuran, toluene, glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dioxane, pyridine, dimethyl sulfoxide, dimethyl formamide, N-methylimidazole, acetonitrile, and polyethylene glycol dimethyl ether.

13. The synthesis method of claim 8, wherein the electrolyte solution has an electrolyte concentration of 0.1-1.5 mol/L.

14. The synthesis method of claim 8, wherein the ionic liquid is 1-methyl-(1-butyl) pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSl).

15. The synthesis method of claim 8, wherein the non-aqueous solvent is THF and the solvent of the electrolyte solution is PYR14TFSl/THF.

16. The synthesis method of claim 8, wherein the Lewis acid is MgCl.sub.2.

17. The synthesis method of claim 8, wherein the Lewis base is selected from the group consisting of AlCl.sub.3, AlF.sub.3, and BCl.sub.3.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 is a crystal structural view of the obtained [Mg(THF).sub.6] [AlCl.sub.4].sub.2 in embodiment 1 of the invention;

(2) FIG. 2 is a cyclic voltammogram of the [Mg(THF).sub.6] [AlCl.sub.4].sub.2 in embodiment 7 of the invention;

(3) FIG. 3 is a linearly scanned voltammogram of the [Mg(THF).sub.6] [AlCl.sub.4].sub.2 in embodiment 7 of the invention;

(4) FIG. 4 is a cyclic voltammogram of the [Mg(DMSO).sub.6] [AlCl.sub.4].sub.2 in embodiment 8 of the invention;

(5) FIG. 5 is a cyclic voltammogram of the [Mg(DMSO).sub.6] [AlF.sub.4].sub.2 in embodiment 9 of the invention;

(6) FIG. 6 is a first charging-discharging curve diagram of a magnesium sulphur battery in embodiment 12 of the invention;

(7) FIG. 7 is a cycle performance test diagram of the magnesium sulphur battery in embodiment 12 of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(8) Typical embodiments that embody the characteristics and advantages are described in detail below. It should be understood that the invention can have various variations at different embodiments, all within the scope of the invention, and the descriptions and drawings thereof should be regarded as explanation in nature, instead of limits in the invention.

(9) Unless otherwise defined, all technical and scientific terms used in the text have meanings generally understood by those skilled in the technical field of the invention. The terms in text of the description of the invention are used only for the purpose of describing the specific embodiments of the invention, instead of limiting the invention.

(10) Embodiment 1: 56 mg of anhydrous magnesium chloride (MgCl.sub.2) and 158 mg of anhydrous aluminum chloride (AlCl.sub.3) react in 1 mL of ionic liquid, namely 1-methyl-(1-butyl) pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI), at a temperature of 95 C. for 24 hours to obtain a light yellow solution; the obtained solution is cooled to room temperature and then added into 1 mL of THF; and 0.3M rechargeable magnesium electrolyte solution is obtained. The crystal structure represents that the electrolyte salt is [Mg(THF).sub.6] [AlCl.sub.4].sub.2, and the crystal structure can be seen in FIG. 1. The theoretical values according to the element analysis include C: 36.28, and H: 6.09; and the measured values include C: 36.27%, and N: 6.10%. Raman spectrum test results show that 350 cm.sup.1 is the characteristic peak of the anions AlCl.sub.4.sup., and the Raman peak of other aluminum chloride anions is not seen.

(11) Embodiment 2: 56 mg of anhydrous magnesium chloride (MgCl.sub.2) and 158 mg of anhydrous aluminum chloride (AlCl.sub.3) react in 1 mL of triethylene glycol dimethyl ether (TEGDME) at a temperature of 30 C. for 24 hours to obtain a light yellow solution; the obtained solution is cooled to room temperature; and then, 0.6M rechargeable magnesium electrolyte solution is obtained. The crystal structure represents that the electrolyte salt is [Mg(TEGDME).sub.2] [AlCl.sub.4].sub.2. The theoretical values according to the element analysis include C: 22.87, and H: 4.48; and the measured values include C: 22.89%, and N: 4.47%. Raman spectrum test results show that 350 cm.sup.1 is the characteristic peak of the anions AlCl.sub.4.sup., and the Raman peak of other aluminum chloride anions is not seen.

(12) Embodiment 3: 56 mg of anhydrous magnesium chloride (MgCl.sub.2) and 158 mg of anhydrous aluminum chloride (AlCl.sub.3) react in 1 mL of toluene at a temperature of 100 C. for 24 hours to obtain a light yellow solution; the obtained solution is cooled to room temperature; and then, 0.6M rechargeable magnesium electrolyte solution is obtained. The crystal structure represents that the electrolyte salt is [Mg(toluene).sub.6] [AlCl.sub.4].sub.2. The theoretical values according to the element analysis include C: 55.15, and H: 5.29; and the measured values include C: 55.10%, and H: 5.30%. Raman spectrum test results show that 350 cm.sup.1 is the characteristic peak of the anions AlCl.sub.4.sup., and the Raman peak of other aluminum chloride anions is not seen.

(13) Embodiment 4: 56 mg of anhydrous magnesium chloride (MgCl.sub.2) and 158 mg of anhydrous aluminum chloride (AlCl.sub.3) react in 1 mL of polyethylene glycol dimethyl ether at a temperature of 95 C. for 24 hours to obtain a light yellow solution; the obtained solution is cooled to room temperature; and then, 0.6M rechargeable magnesium electrolyte solution is obtained. Raman spectrum test results show that 350 cm.sup.1 is the characteristic peak of the anions AlCl.sub.4.sup., and the Raman peak of other aluminum chloride anions is not seen.

(14) Embodiment 5: 56 mg of anhydrous magnesium chloride (MgCl.sub.2) and 158 mg of anhydrous aluminum chloride (AlCl.sub.3) react in 1 mL of dimethyl sulfoxide (DMSO) at a temperature of 120 C. for 24 hours to obtain a light yellow solution; the obtained solution is cooled to room temperature; and then, 0.6M rechargeable magnesium electrolyte solution is obtained. The crystal structure represents that the electrolyte salt is [Mg(DMSO).sub.6] [AlCl.sub.4].sub.2. The theoretical values according to the element analysis include C: 17.35, and H: 4.37; and the measured values include C: 17.36%, and H: 4.37%. Raman spectrum test results show that 350 cm.sup.1 is the characteristic peak of the anions AlCl.sub.4.sup., and the Raman peak of other aluminum chloride anions is not seen.

(15) Embodiment 6: 56 mg of anhydrous magnesium chloride (MgCl.sub.2) and 100.8 mg of anhydrous aluminum fluoride (AlF.sub.3) react in 1 mL of ionic liquid, namely 1-methyl-(1-butyl) pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI), at a temperature of 150 C. for 24 hours to obtain a light yellow solution; the obtained solution is cooled to room temperature and then added into 1 mL of THF; and 0.3M rechargeable magnesium electrolyte solution is obtained. The crystal structure represents that the electrolyte salt is [Mg(THF).sub.6] [AlClF.sub.3].sub.2. The theoretical values according to the element analysis include C: 41.43, and H: 6.95; and the measured values include C: 41.40%, and H: 6.97%.

(16) Embodiment 7: 19 mg of anhydrous magnesium chloride (MgCl.sub.2) and 100.8 mg of anhydrous aluminum fluoride (AlF.sub.3) react in 1 mL of dimethyl sulfoxide (DMSO) at a temperature of 200 C. for 24 hours to obtain a light yellow solution; the obtained solution is cooled to room temperature; and then, 0.6M rechargeable magnesium electrolyte solution is obtained. The crystal structure represents that the electrolyte salt is [Mg(DMSO).sub.6] [AlF.sub.4].sub.2. The theoretical values according to the element analysis include C: 20.62, and H: 5.19; and the measured values include C: 20.61%, and H: 5.20%.

(17) Embodiment 8: 56 mg of anhydrous magnesium chloride (MgCl.sub.2) and 69 mg of anhydrous boron chloride (BCl.sub.3) react in 1 mL of ionic liquid, namely 1-methyl-(1-butyl) pyrrolidinium bis_(trifluoromethanesulfonyl)_imide (PYR14TFSI), at a temperature of 95 C. for 24 hours to obtain a light yellow solution; the obtained solution is cooled to room temperature and then added into 1 mL of THF; and 0.3M rechargeable magnesium electrolyte solution is obtained. The crystal structure represents that the electrolyte salt is [Mg(THF).sub.6] [BCl.sub.4].sub.2. The theoretical values according to the element analysis include C: 37.82, and H: 6.35; and the measured values include C: 37.82%, and H: 6.34%.

(18) Embodiment 9: Platinum is used as a working electrode; the PYR14TFSI/THF solution of 0.3M magnesium salt ([Mg(THF).sub.6] [AlCl.sub.4].sub.2) is used as the electrolyte solution; and metal magnesium is used as a counter electrode and a reference electrode. The three units are assembled to form a three-electrode system. The system undergoes cyclic voltammetry in an argon glove box. The scanning rate is 25 mV/s. The results of cyclic voltammetry and linearly scanned voltammetry can be seen in FIG. 2 and FIG. 3. From FIG. 2 it can be known that the oxidation-reduction process that appears nearby 0.2V and 0.2V vs. Mg corresponds to the deposition and dissolution of magnesium, and the oxidation potential of the anode can reach 2.5V vs. Mg.

(19) Embodiment 10: Copper is used as a working electrode; the PYR14TFSI/THF solution of 0.3M magnesium salt ([Mg(DMSO).sub.6] [AlCl.sub.4].sub.2) is used as the electrolyte solution; and metal magnesium is used as a counter electrode and a reference electrode. The three units are assembled to form a three-electrode system. The system undergoes cyclic voltammetry in an argon glove box. The scanning rate is 25 mV/s. The cyclic voltammetry results can be seen in FIG. 4. From FIG. 4 it can be known that the oxidation-reduction process that appears nearby 0.2V and 0.2V vs. Mg corresponds to the deposition and dissolution of magnesium.

(20) Embodiment 11: Platinum is used as a working electrode; the DMSO solution of 0.3M magnesium salt ([Mg(DMSO).sub.6] [AlF.sub.4].sub.2) is used as the electrolyte solution; and metal magnesium is used as a counter electrode and a reference electrode. The three units are assembled to form a three-electrode system. The system undergoes cyclic voltammetry in an argon glove box. The scanning rate is 25 mV/s. The cyclic voltammetry results can be seen in FIG. 5. From FIG. 5 it can be known that the oxidation-reduction process that appears nearby 0.2V and 0.2V vs. Mg corresponds to the deposition and dissolution of magnesium, and the oxidation potential of the anode can reach 2.6V vs. Mg.

(21) Embodiment 12: A sulphur-carbon compound (S/C) is used as the electrolyte solution; the PYR14TFSI/THF solution of 0.3M magnesium salt ([Mg(THF).sub.6] [AlCl.sub.4].sub.2) is used as the electrolyte solution; and the metal magnesium is used as the cathode. The three units are assembled to form a magnesium-sulphur battery. The charging-discharging curve and the cyclic performance test results can be seen in FIG. 6 and FIG. 7. From FIG. 6 and FIG. 7 it can be known that magnesium-sulphur battery has an initial discharging capacity of approx. 700 mAh/G and has a cycle number of greater than 20.

(22) All product structural parameters, all reaction participants and process conditions in the above embodiments are all typical examples. However, a large number of experiments made by the inventor show that other different structural parameters, other types of reaction participants and process conditions are also applicable, and can achieve the Claimed technical effects of the invention.

(23) It should be explained that the terms comprise, include or any other synonyms are intended to cover non-exclusive inclusion, so the processes, methods, articles or devices of a series of elements include not only those elements, but also other elements which are not clearly listed, or also include all inherent factors of those processes, methods, articles or terminals. In the case of no more limit, the elements defined by the sentence comprising/including a/an . . . should not exclude that the processes, methods, articles or devices including the elements also include other identical elements.

(24) The above embodiments are specific embodiments of the invention. It should be noted that, for those ordinarily skilled in the art, various improvements and changes can be made on the basis of the principle of the invention. The improvements and changes shall also fall within the protective scope of the invention.