Non-activated magnesium battery magnesium-aluminum-chlorine compound electrolyte and preparation method thereof

Abstract

The invention relates to the field of battery electrolyte, and particularly discloses non-activated magnesium battery magnesium-aluminum-chlorine compound electrolyte and a preparation method thereof. The raw materials comprise a solvent, an ionic liquid, at least one magnesium salt and at least one other salt; the solvent is at least one of ethylene glycol dimethyl ether and tetrahydrofuran; the ionic liquid is one or more of 1-methyl-1-amyl pyrrolidinium bis (trifluoromethanesulfonyl) imine, 1-methyl-1-n-octyl pyrrolidinium bis (trifluoromethanesulfonyl) imine, 1-allyl-1-methyl pyrrolidinium bis (trifluoromethanesulfonyl) imine, 1-methyl-3-(4-sulfobutyl) imidazolium bis (trifluoromethanesulfonyl) imine, N-methyl, N-dimethyl, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N, N-dimethyl-N- the catalyst is selected from at least one of ethyl pyrrolidine bis (trifluoromethanesulfonyl) imide salt and 1-methylpyridinium bis (trifluoromethanesulfonyl) imide. According to the non-activated magnesium battery magnesium-aluminum-chlorine compound electrolyte, the problems that the manufacturing cost of the electrolyte is relatively high and the electrolyte needs to be activated during use can be solved.

Description

Technical Field

[0001] The invention relates to the field of battery electrolytes, and in particular to a magnesium-aluminum-chlorine complex electrolyte for a non-activated magnesium battery and a preparation method thereof. Background Art

[0002] Magnesium ion batteries have the advantages of good safety, high theoretical specific capacity, and low cost, and are considered to be one of the most promising electrochemical energy storage systems in the 21st century. However, typical electrolytes composed of simple magnesium salts (such as magnesium chloride, magnesium perchlorate, and magnesium sulfate) and conventional polar solvents (such as ethylene carbonate, propylene carbonate, and acetonitrile) easily react with the magnesium negative electrode to form a passivation film that hinders the reversible deposition / dissolution of magnesium ions, which greatly limits the range of electrolyte components and seriously hinders the development and application of magnesium ion batteries.

[0003] The magnesium-aluminum-chlorine composite electrolyte system avoids many limitations of organic metal components, has a wide source of raw materials, a simple and low-cost preparation process, can achieve reversible deposition / dissolution of magnesium ions, and has good compatibility with the positive electrode of magnesium ion batteries to a certain extent, and has broad prospects for commercial application.

[0004] The current magnesium-aluminum complex electrolyte is shown in a magnesium secondary battery electrolyte and its preparation method and application disclosed in patent No. CN202410458495.6, wherein the magnesium secondary battery electrolyte is a composite system comprising the following components; at least one magnesium salt, a solvent and an additive; the concentration of each magnesium salt after being dissolved in the solvent is independently 0.05-1.5 mol / L, preferably 0.3-1.0 mol / L; the concentration of the additive in the electrolyte is 0.01-2.0 mol / L, preferably 0.2-0.6 mol / L. The magnesium salt is a mononuclear magnesium cation salt. Preferably, the chemical formula of the mononuclear magnesium cation salt is [MgL1m][ML2n]2, wherein L1 is tetrahydrofuran, ethylene glycol dimethyl ether, dioxane, butyl ether, triethylene glycol dimethyl ether or polyethylene glycol dimethyl ether, M is Ga3+, Al3+ or Gd3+, L2 is a halogen ion, m is any integer from 0 to 6, and n is any integer from 0 to 4.

[0005] However, the above-mentioned magnesium-aluminum-chlorine composite electrolyte system still has an "activation" process, which increases the production cost and time of the electrolyte and limits its practical application. Therefore, a non-activated magnesium-aluminum-chlorine composite electrolyte for magnesium ion batteries is needed. Summary of the invention

[0006] The present invention aims to provide a magnesium-aluminum-chlorine complex electrolyte for a non-activated magnesium battery and a preparation method thereof, so as to solve the problems of high production cost of the electrolyte and the need for activation during use.

[0007] To achieve the above object, the present invention adopts the following technical scheme: an activated magnesium battery magnesium aluminum chloride complex electrolyte, the raw materials include a solvent, an ionic liquid, at least one magnesium salt and at least one other salt, the concentration of the magnesium salt and the other salt are both 0.01-1.0 mol / L; the solvent is at least one of ethylene glycol dimethyl ether (DME) and tetrahydrofuran (THF);

[0008] The ionic liquid is at least one of 1-methyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-n-octylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-allyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-3-(4-sulfobutyl)imidazolium bis(trifluoromethanesulfonyl)imide, N-methyl, ethylpyrrolidinium bis(trifluoromethanesulfonyl)imide salt, and 1-methylpyridinium bis(trifluoromethanesulfonyl)imide.

[0009] The beneficial effects of this solution are as follows: the raw materials of the electrolyte in this solution include ionic liquids. In the traditional battery field, ionic liquids are usually used to improve the electrochemical performance of the electrolyte. The current magnesium battery magnesium aluminum chloride electrolyte requires an "activation process" after preparation. Figure 1 As shown, when activation is not completed, the performance of the electrolyte is low and cannot be used normally; after activation is completed, the performance of the electrolyte increases significantly and can only be used normally.

[0010] However, the inventor discovered during an accidental experiment that the magnesium battery produced by mixing the ionic liquid in the present solution with the magnesium aluminum chloride electrolyte of the original magnesium battery exhibited good electrochemical properties without activation: after continuous testing, it was found that even after an activation time longer than that of the existing electrolyte, the performance of the electrolyte in the present solution was still basically close to the performance at the beginning of the test, which just shows that the electrolyte has skipped the activation process at the beginning and does not need to be activated before use, so that the electrolyte of the present invention can be used normally after preparation, with low production cost, and effectively improving the convenience and efficiency of use.

[0011] Furthermore, the concentration of each salt is less than or equal to 0.5 mol / L.

[0012] The beneficial effects of this solution are: the electrolyte in this solution has better performance, and can avoid the need for filtration due to too much salt, and can also avoid too little salt resulting in too little effective substance in the electrolyte.

[0013] Furthermore, the volume ratio of the ionic liquid to the solvent is 0.01-0.2:3.

[0014] Furthermore, the volume ratio of the ionic liquid to the solvent is 0.02 to 0.1:3.

[0015] The beneficial effect of this solution is that the electrochemical performance of the electrolyte in this solution is better, which is beneficial to improving the overall performance of the electrolyte.

[0016] Furthermore, the solvent is tetrahydrofuran and ethylene glycol dimethyl ether, the ionic liquid is 1-methyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, the magnesium salt is magnesium chloride, and the other salt is aluminum chloride.

[0017] The beneficial effects of this solution are: the existing magnesium aluminum chloride electrolyte needs to undergo an "activation process" to change the chemical environment of the electrolyte to promote (Mg2Cl3)(THF)6 + 、AlCl4 - The ionic liquid electrolyte used in this scheme includes cations and bis(trifluoromethanesulfonyl)imide anions. The bis(trifluoromethanesulfonyl)imide anions and other cations will partially decompose to produce more active substances such as AlCl3F - Plasma, the increase in the number of ions can improve the ionic conductivity of the electrolyte. At the same time, AlCl3F - As anion, it can also react with Mg 2+ Combined, magnesium ions are transported when the battery is in use, thus skipping the "activation" process.

[0018] A method for preparing a magnesium-aluminum-chlorine complex electrolyte for an activated magnesium battery comprises the following steps:

[0019] Step 1, mixing a solvent, an ionic liquid, a magnesium salt and other salts to obtain a mixed solution;

[0020] Step 2, stirring at 20-30° C. until the solution is clear and transparent to obtain an electrolyte.

[0021] The beneficial effects of this solution are: the preparation process of this solution can be completed at room temperature without the need for high temperature and other conditions, the preparation is more convenient and simple, and the energy consumption is lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a test result diagram of Example 1 of the present invention using cyclic voltammetry;

[0023] Figure 2 This is a test result diagram of Example 5 of the present invention using cyclic voltammetry;

[0024] Figure 3 This is a test result diagram of Example 5 of the present invention using linear sweep voltammetry;

[0025] Figure 4 This is a test result diagram of comparative example 1 of the present invention using cyclic voltammetry;

[0026] Figure 5This is a test result diagram of comparative example 2 of the present invention using cyclic voltammetry;

[0027] Figure 6 This is a test result diagram of comparative example 3 of the present invention using cyclic voltammetry;

[0028] Figure 7 This is a test result diagram of comparative example 4 of the present invention using cyclic voltammetry. DETAILED DESCRIPTION

[0029] The following is further described in detail through specific implementation methods:

[0030] Example

[0031] The invention discloses a magnesium-aluminum-chlorine complex electrolyte for a non-activated magnesium battery, wherein the raw materials include a solvent, an ionic liquid, at least one magnesium salt and at least one other salt, wherein the solvent is at least one of tetrahydrofuran and ethylene glycol dimethyl ether;

[0032] The ionic liquid is at least one of 1-methyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-n-octylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-allyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-3-(4-sulfobutyl)imidazolium bis(trifluoromethanesulfonyl)imide, N-methyl, ethylpyrrolidinium bis(trifluoromethanesulfonyl)imide salt, and 1-methylpyridinium bis(trifluoromethanesulfonyl)imide;

[0033] The magnesium salt is magnesium chloride, and the other salt is aluminum chloride. The concentrations of magnesium chloride and aluminum chloride are both 0.01-1.0 mol / L, and the volume ratio of the ionic liquid to the solvent is 0.01-0.2:3. Specifically, the volume ratio of the ionic liquid to the solvent is 0.02-0.1:3, and the concentrations of magnesium chloride and aluminum chloride in the prepared electrolyte are less than or equal to 0.5 mol / L.

[0034] The present invention discloses Examples 1 to 7. The volumes of tetrahydrofuran, dimethyl ether, ionic liquid, the types of ionic liquid, and the amounts of magnesium chloride and aluminum chloride in Examples 1 to 7 are specifically shown in Table 1 below:

[0035]

[0036] The present invention discloses comparative examples 1 to 5, which are specifically as follows:

[0037] Comparative Example 1: The raw materials are magnesium chloride, aluminum chloride, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4), DME, and THF, as shown in the reference: Magnesium chloride-aluminum chloride-EMImBF4 / organic ether rechargeable magnesium battery electrolyte [J]. Journal of Chemistry in Universities, 2024, 45(5): 120-128. DOI: 10.7503 / cjcu20240010.

[0038] Comparative Example 2: The raw materials are magnesium chloride, aluminum chloride and THF, as shown in the reference: Effect of Concentration on the Electrochemistry and Speciation of the MagnesiumAluminum Chloride Complex Electrolyte Solution[J].ACS applied materials&interfaces,2017,9(41):35729-35739.DOI:10.1021 / acsami.7b08088.

[0039] Comparative Example 3: The raw materials are magnesium chloride, aluminum chloride and DME, as shown in the reference: Electrolytic Conditioning of a Magnesium Aluminum Chloride Complex for Reversible Magnesium Deposition[J]. The journal of physical chemistry, C. Nanomaterials and interfaces, 2014, 118(48): 27623-27630. DOI: 10.1021 / jp506951b.

[0040] Comparative Example 4: The raw materials are magnesium chloride, boron trichloride and DME, as shown in the reference: Exploring Salt and Solvent Effects in Chloride-Based Electrolytes for Magnesium Electrodeposition and Dissolution [J]. The journal of physical chemistry, C. Nanomaterials and interfaces, 2015, 119 (24): 13524-13534. DOI: 10.1021 / acs.jpcc.5b03508.

[0041] The present invention also discloses a method for preparing a magnesium-aluminum-chlorine complex electrolyte for an activated magnesium battery, comprising the following steps:

[0042] Step 1, mixing a solvent, an ionic liquid, a magnesium salt and other salts to obtain a mixed solution;

[0043] Step 2, stirring at 20-30° C. until the solution is clear and transparent to obtain an electrolyte.

[0044] The present invention uses cyclic voltammetry and linear sweep voltammetry to test the electrolytes prepared in Examples 1 to 7. The results of cyclic voltammetry of Example 1 with activation process are as follows: Figure 1 The results of cyclic voltammetry without activation process are shown as Figure 2 The results of linear sweep voltammetry are shown in Figure 3 As shown. From the above tests, we can see that:

[0045] 1. According to Figure 1 It can be seen that the electrolyte prepared in Example 1 did not show a peak until the 40th cycle of testing, that is, a significant current appeared, and as the test continued, the performance of the electrolyte began to improve, indicating that the electrolyte was in the activation process before the 40th cycle and continued to activate during the 40th to 100th cycles. Figure 2 It can be seen that the electrolyte of the present invention has a peak when the first round of testing is carried out, and in the subsequent tests, the peak value of the peak is close to the peak value of the first round of the peak, indicating that at the beginning of the test, the performance of the electrolyte has reached the use state without an activation process.

[0046] 2. According to Figure 1 : The current density of the 40th cycle is 0.99mA / cm 2 The maximum current density is 7.4 mA / cm at 80 cycles. 2 , 100 cycles of current density is 6.6mA / cm 2 ,so Figure 1 In the figure, 100 circles have exceeded the maximum value and started to decay.

[0047] according to Figure 2 : The current density of the 75th and 100th cycles is 21.9 mA / cm 2 , the first circle is 26.3mA / cm 2 , so the current of the present invention is definitely greater than that of the comparative example.

[0048] 3. Similarly, according to Figures 4 to 7 It can be seen that the electrolytes in Comparative Examples 1 to 4 all undergo activation processes.

[0049] 4. According to Figure 3 The oxidation potential of the electrolyte in the present invention is above 2 V, indicating that the electrolyte prepared by the present invention has a good electrochemical window.

[0050] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A magnesium-aluminum-chlorine complex electrolyte for an activated magnesium battery, characterized in that: The raw materials include a solvent, an ionic liquid, at least one magnesium salt and at least one other salt, wherein the concentrations of the magnesium salt and the other salt are both 0.01 to 1.0 mol / L; the solvent is at least one of ethylene glycol dimethyl ether (DME) and tetrahydrofuran (THF); The ionic liquid is at least one of 1-methyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-n-octylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-allyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-methyl-3-(4-sulfobutyl)imidazolium bis(trifluoromethanesulfonyl)imide, N-methyl, ethylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, and 1-methylpyridinium bis(trifluoromethanesulfonyl)imide.

2. The magnesium-aluminum-chlorine complex electrolyte for a non-activated magnesium battery according to claim 1, characterized in that: The concentration of each salt is less than or equal to 0.5 mol / L.

3. The magnesium-aluminum-chlorine complex electrolyte for a non-activated magnesium battery according to claim 1, characterized in that: The volume ratio of the ionic liquid to the solvent is 0.01-0.2:

3.

4. The magnesium-aluminum-chlorine complex electrolyte for a non-activated magnesium battery according to claim 3, characterized in that: The volume ratio of the ionic liquid to the solvent is 0.02-0.1:

3.

5. The magnesium-aluminum-chlorine complex electrolyte for non-activated magnesium battery according to any one of claims 1 to 4, characterized in that: The solvents are tetrahydrofuran and ethylene glycol dimethyl ether, the ionic liquid is 1-methyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide, the magnesium salt is magnesium chloride, and the other salt is aluminum chloride.

6. A method for preparing a magnesium-aluminum-chlorine complex electrolyte for an activated magnesium battery, characterized in that: The following steps are involved: Step 1, mixing a solvent, an ionic liquid, a magnesium salt and other salts to obtain a mixed solution; Step 2, stirring at 20-30° C. until the solution is clear and transparent to obtain an electrolyte.

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