Magnesium battery electrolyte, its manufacturing method, and magnesium battery

Abstract

This application discloses an electrolyte for a magnesium battery, a manufacturing method thereof, and a magnesium battery. The electrolyte of the magnesium battery includes a non-aqueous solvent and an electrolyte salt, the non-aqueous solvent being one or more selected from the group consisting of imidazole-based ionic liquids, pyrrole-based ionic liquids, piperidine-based ionic liquids, ether-based compounds, ester-based compounds, pyridine-based compounds, nitrile-based compounds, sulfone-based compounds, and ketone-based compounds, and the chemical formula of the electrolyte salt is [Mg m Li n X o (HMDS) 2m+n-o R p ]·M q The electrolyte for magnesium batteries according to the present application has good stability, relatively strong resistance to water and impurities, and excellent electrochemical performance due to the synergistic effects of each component, and can promote the reversible precipitation and dissolution of magnesium, reduce overvoltage, inhibit magnesium salt from forming a passivation layer on the surface of the anode, and improve the charge / discharge specific capacity and cycle stability of magnesium batteries.

Description

[Technical field]

[0001] This application claims priority to Chinese Patent Application No. 202210139050.2, entitled "Electrolyte for Magnesium Battery, Its Manufacturing Method, and Magnesium Battery," filed on February 15, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present application belongs to the field of energy technology, and specifically relates to an electrolyte for a magnesium battery, a manufacturing method thereof, and a magnesium battery. [Background technology]

[0003] Magnesium metal has abundant storage capacity, low cost, is environmentally friendly, has relatively stable physicochemical properties, is not prone to dendrite growth, and has a high theoretical volumetric capacity (3833 mA h / cm 3 Magnesium battery systems, which use metallic magnesium as the anode material, have advantages such as high energy density, low cost, and high safety, and are one of the most promising new energy storage systems.

[0004] However, because magnesium ions have a high charge density and a low reduction potential (-2.37V vs. SHE), most organic solvents and magnesium salts react with metallic magnesium, forming a passivation layer on the surface of the magnesium metal that inhibits the conduction of magnesium ions, which is detrimental to the operation of magnesium batteries. In addition, the surface of metallic magnesium is easily affected by impurities (e.g., traces of water, oxygen gas, carbon dioxide, etc.), and the interface between the electrode and the electrolyte becomes unstable during long-term charging and discharging, making it impossible to effectively conduct magnesium ions. Furthermore, the overvoltage of the battery during charging and discharging becomes large, precipitation and dissolution become uneven, which ultimately leads to short circuit problems and ultimately to the failure of the magnesium battery. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of this, the present application provides an electrolyte for a magnesium battery, a manufacturing method thereof, and a magnesium battery, in order to solve the problem that the electrolyte for a magnesium battery has low interface stability performance, is easily affected by impurities, and cannot effectively conduct magnesium ions.

[0006] On the one hand, the examples of the present application are An electrolyte for a magnesium battery comprising a non-aqueous solvent and an electrolyte salt, the non-aqueous solvent is one or more selected from the group consisting of imidazole-based ionic liquids, pyrrole-based ionic liquids, piperidine-based ionic liquids, ether-based compounds, ester-based compounds, pyridine-based compounds, nitrile-based compounds, sulfone-based compounds, and ketone-based compounds; The chemical formula of the electrolyte salt is [Mg m Li n X o (HMDS) 2m+n-o R p ]·M q and wherein X is selected from a halogen ion and / or a bistrifluoromethanesulfonylimide ion; HMDS stands for hexamethyldisilazane ion. R is one or more selected from an alkyl group, a fluoroalkyl group, and an aryl group, M is a non-aqueous solvent molecular complexing agent; m is any integer selected from 1 to 6, n is any integer selected from 1 to 6, o is any integer selected from 1 to 6, p is any integer selected from 0 to 6, and q is any integer selected from 1 to 20. Provides electrolyte for magnesium batteries.

[0007] According to an embodiment of one aspect of the present application, the imidazole-based ionic liquid is selected from 1-ethyl-3-methylimidazolium tetrafluoroborate and / or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonic acid)imide salt; The pyrrole-based ionic liquid is selected from N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide salts; The piperidine-based ionic liquid is selected from N-butyl-N-methylpiperidinium bis(trifluoromethanesulfonyl)imide salts.

[0008] According to an embodiment of one aspect of the present application, the ether-based compound is one or more selected from tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dioxane, and polyethylene glycol dimethyl ether; The ester compound is selected from ethyl acetate, the pyridine-based compound is one or more selected from pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,6-dichloropyridine, and 2-aminopyridine; The nitrile compound is selected from acetonitrile; The sulfone compound is selected from dimethyl sulfoxide.

[0009] According to an embodiment of one aspect of the present application, the non-aqueous solvent is tetrahydrofuran, and the halogen ion is a chloride ion.

[0010] According to an embodiment of one aspect of the present application, p is 1, 2, 3, 4, 5, or 6.

[0011] On the other hand, the examples of the present application A method for producing an electrolyte for a magnesium battery, comprising the steps of: uniformly mixing anhydrous magnesium salt, anhydrous lithium salt, and a non-aqueous solvent; reacting the mixture at 25°C to 200°C for 3 hours to 48 hours; and cooling the mixture to -30°C to 25°C to obtain an electrolyte for a magnesium battery, The anhydrous magnesium salt is one or more selected from magnesium chloride, magnesium fluoride, magnesium bromide, magnesium iodide, magnesium bis(hexamethyldisilazide), magnesium bis(trifluoromethanesulfonyl)imide, and Grignard reagents; the anhydrous lithium salt is selected from lithium bis(trimethylsilyl)amide and a second anhydrous lithium salt, the second anhydrous lithium salt being one or more selected from lithium chloride, lithium fluoride, lithium bromide, lithium iodide, and lithium bis(trifluoromethanesulfonyl)imide; A method for producing an electrolyte for a magnesium battery is provided.

[0012] According to an embodiment of another aspect of the present application, the molar ratio of the anhydrous magnesium salt to the anhydrous lithium salt is 1:(0.1-4).

[0013] According to an embodiment of another aspect of the present application, the concentration of the electrolyte salt is 0.1 to 10 mol / L.

[0014] According to an embodiment of another aspect of the present application, the concentration of the electrolyte salt is 0.1 to 3 mol / L.

[0015] Furthermore, an embodiment of the present application provides a magnesium battery including a positive electrode, a separator, a negative electrode and an electrolyte of the magnesium battery. Effect of the Invention

[0016] Compared with the prior art, the present application has at least the following beneficial effects:

[0017] (1) The electrolyte of the magnesium battery according to the present application, due to the synergistic effects of the components, imparts good stability, relatively strong resistance to water and impurities, and excellent electrochemical performance, while promoting the reversible precipitation and dissolution of magnesium, reducing overvoltage, and inhibiting the formation of a passivation layer by magnesium salts on the surface of the anode, thereby improving the charge / discharge specific capacity and cycle stability of the magnesium battery.

[0018] (2) The manufacturing method of the magnesium battery electrolyte according to the present application is simple and easy to implement, has low requirements for equipment, is compatible with conventional processes, and has the potential for large-scale application.

[0019] (3) The magnesium battery according to the present application has good charge / discharge specific capacity and long cycle life. As can be seen from Fig. 10, the magnesium battery made of the above-mentioned magnesium battery electrolyte has a relatively high charge / discharge specific capacity and a long cycle life. [Brief description of the drawings]

[0020] In order to more clearly describe the technical solutions of the embodiments of the present application, the drawings that need to be used in the embodiments of the present application are briefly described below. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can also obtain other drawings based on the drawings without creative labor. [Figure 1] 1 is a Raman spectrum of the electrolyte of the magnesium battery in Example 1 of the present application. [Diagram 2] 1 is a nuclear magnetic resonance spectrum of the electrolyte of the magnesium battery of Example 1 of the present application. [Diagram 3] 1 shows cyclic voltammetry curves in which metallic magnesium is precipitated and dissolved in the electrolyte of the magnesium battery of Example 2 of the present application without impurity interference. [Figure 4] 1 shows cyclic voltammetry curves of the precipitation and dissolution of metallic magnesium when trace amounts of water, carbon dioxide, and oxygen gas are present in the electrolyte of the magnesium battery of Example 2 of the present application. [Diagram 5] 1 shows cyclic voltammetry curves of precipitation and dissolution of metallic magnesium when 1000 ppm of H2O interference is present in the electrolyte of the magnesium battery of Example 2 of the present application. [Figure 6]1 shows cyclic voltammetry curves of precipitation and dissolution of metallic magnesium when trace amounts of water, carbon dioxide, and oxygen gas are present in the electrolyte of a magnesium battery according to Comparative Example 1 of the present application. [Figure 7] 1 shows cyclic voltammetry curves of precipitation and dissolution of metallic magnesium when 400 ppm of H2O interference is present in the electrolyte of a magnesium battery of Comparative Example 1 of the present application. [Figure 8] 1 is a linear scanning curve showing the precipitation and dissolution of metallic magnesium when trace amounts of water, carbon dioxide, and oxygen gas are present in the electrolyte of the magnesium battery of Example 2 of the present application. [Figure 9] 1 is a graph showing the charge / discharge specific capacity-voltage of the magnesium battery of Example 2 of the present application. [Figure 10] 1 is a graph showing the charge / discharge cycle-specific capacity of the magnesium battery of Example 2 of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In order to make the purpose, technical solution and beneficial technical effects of the present application clearer, the present application will be further described in detail below in combination with examples. It should be understood that the examples described herein are only for illustrating the present application, and do not limit the present application.

[0022] In this application, for simplicity, only some numerical ranges are explicitly disclosed. However, any lower limit can be combined with any upper limit to form a range not explicitly described, and any lower limit can be combined with any other lower limit to form a range not explicitly described, and similarly, any upper limit can be combined with any other upper limit to form a range not explicitly described. Also, although not explicitly described, each point or single value between the endpoints of a range is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit, or can be combined with any other lower limit or upper limit to form a range not explicitly described.

[0023] In the description of this application, for clarity, unless otherwise stated, "more than" and "less than" are inclusive, and "multiple" in "one or more" means two and more.

[0024] The above application contents of this application are not intended to describe each embodiment or each implementation mode of the disclosure in this application. The following description will more specifically describe the embodiments by way of examples. In several places in this specification, guidance is provided by a series of examples, which can be used in various combinations. In each example, the examples are listed as representative groups, but should not be construed as exhaustive.

[0025] In the electrolytes for magnesium batteries currently developed, inorganic salts and their related systems, such as inorganic magnesium aluminum halide salts (MACC) systems and inorganic magnesium lithium chloride salts (MLCC) systems, have great advantages in terms of applicability due to their low cost and advantages such as one-step synthesis. However, such systems have poor stability and are easily affected by impurities (such as small amounts of water, oxygen gas, carbon dioxide, etc.), which can cause passivation of the magnesium sheet surface, and further increase the overvoltage during battery charge and discharge, leading to uneven precipitation and dissolution, which can lead to short circuit problems and ultimately to failure of the magnesium battery.

[0026] Based on this, the inventors have conducted extensive research, with the objective of providing an electrolyte with good water and impurity resistance and excellent electrochemical performance, promoting the reversible precipitation and dissolution of magnesium, reducing overpotential, inhibiting magnesium salt from forming a passivation layer on the anode surface, and further improving the charge / discharge specific capacity and cycle life of magnesium batteries.

[0027] (Electrolyte for Magnesium Batteries) An embodiment of the first aspect of the present application comprises: An electrolyte for a magnesium battery comprising a non-aqueous solvent and an electrolyte salt, the non-aqueous solvent is one or more selected from the group consisting of imidazole-based ionic liquids, pyrrole-based ionic liquids, piperidine-based ionic liquids, ether-based compounds, ester-based compounds, pyridine-based compounds, nitrile-based compounds, sulfone-based compounds, and ketone-based compounds; The chemical formula of the electrolyte salt is [Mg m Li n X o (HMDS) 2m+n-o R p ]·M q wherein X is selected from a halogen ion and / or a bistrifluoromethanesulfonylimide ion, HMDS represents a hexamethyldisilazane ion, R represents one or more groups selected from an alkyl group, a fluoroalkyl group, and an aryl group, M represents a non-aqueous solvent molecule complexing agent, m represents an integer selected from 1 to 6, n represents an integer selected from 1 to 6, o represents an integer selected from 1 to 6, p represents an integer selected from 0 to 6, and q represents an integer selected from 1 to 20. Provides electrolyte for magnesium batteries.

[0028] According to the electrolyte solution for the magnesium battery according to the embodiment of the present application, by adding the above-mentioned electrolyte salt and non-aqueous solvent, it is possible to impart good stability, relatively strong resistance to water and impurities, and excellent electrochemical performance to the electrolyte solution for the magnesium battery, thereby imparting high charge / discharge specific capacity and cycle performance to the magnesium battery.

[0029] Although the negative electrode magnesium metal is relatively stable, it can still react with most reducible compounds such as hydrocarbons, alcohols, phenols, amines, aldehydes, water, carbon dioxide, and oxygen. When these solvents are used in the electrolyte solution, a passivation layer is formed on the surface of the negative electrode magnesium metal, which insulates both electrons and ions, and the Mg 2+However, the non-aqueous solvent in the examples of the present application can realize reversible precipitation and dissolution of magnesium and does not form an insulating phase at the interface between the negative electrode magnesium and the electrolyte, which can promote improvement in the charge / discharge specific capacity and cycle stability of the magnesium battery.

[0030] According to the embodiment of the present application, Mg in the electrolyte salt 2+ , Li + , X - , H.M.D.S. - , R and the non-aqueous solvent molecule complexing agent form aggregates with a cluster structure, and these aggregates can promote the transport of magnesium ions in the electrolyte. - Since it has strong reducing properties, it can react preferentially with trace impurities such as water, titanium dioxide, and oxygen gas, thereby protecting the magnesium negative electrode from passivation and imparting good water resistance to the electrolyte of the magnesium battery.

[0031] In some embodiments, the compound of the formula [Mg m Li n X o (HMDS) 2m+n-o R p ]·M q In the formula, m may be 1, 2, 3, 4, 5, or 6. m may be a range of any combination of the above values.

[0032] In some embodiments, the compound of the formula [Mg m Li n X o (HMDS) 2m+n-o R p ]·M q In the formula, n may be 1, 2, 3, 4, 5, or 6. n may also be a range of any combination of the above values.

[0033] In some embodiments, the compound of the formula [Mg m Li n X o (HMDS) 2m+n-o Rp ]·M q In the formula, o may be 1, 2, 3, 4, 5, or 6. o may be a range of any combination of the above values.

[0034] In some embodiments, the compound of the formula [Mg m Li n X o (HMDS) 2m+n-o R p ]·M q In the formula, p may be 0, 1, 2, 3, 4, 5, or 6. p may also be a range of any combination of the above values.

[0035] In some embodiments, the compound of the formula [Mg m Li n X o (HMDS) 2m+n-o R p ]·M q In the formula, q may be 1, 4, 8, 12, 16, or 20. q may also be a range of any combination of the above values.

[0036] In some embodiments, the imidazole-based ionic liquid is selected from 1-ethyl-3-methylimidazolium tetrafluoroborate and / or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonic acid)imide salts.

[0037] In some embodiments, the pyrrole-based ionic liquid is selected from N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide salts.

[0038] In some embodiments, the piperidine-based ionic liquid is selected from N-butyl-N-methylpiperidinium bis(trifluoromethanesulfonyl)imide salts.

[0039] According to the embodiment of the present application, the ionic liquid has good electrical conductivity and a stable electrochemical potential window, and is capable of preventing the formation of Mg in the electrolyte. 2+This can promote the migration of the charge and further improve the cycle stability of the battery.

[0040] In some embodiments, the ether-based compound is one or more selected from tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dioxane, and polyethylene glycol dimethyl ether.

[0041] In some embodiments, the ester compound is selected from ethyl acetate.

[0042] In some embodiments, the pyridine-based compound is one or more selected from pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,6-dichloropyridine, and 2-aminopyridine.

[0043] In some embodiments, the nitrile compound is selected from acetonitrile.

[0044] In some embodiments, the sulfonic compound is selected from dimethyl sulfoxide.

[0045] In some embodiments, the non-aqueous solvent is tetrahydrofuran and the halogen ion is a chloride ion.

[0046] According to the examples of the present application, when the non-aqueous solvent is tetrahydrofuran and the halogen ion is a chloride ion, the aggregates of the formed cluster structure are more stable, have better resistance to water and impurities, and are more likely to undergo reversible precipitation and dissolution of magnesium and reduce overvoltage.

[0047] In some embodiments, the concentration of the electrolyte salt in the electrolyte solution is 0.1 mol / L to 10 mol / L. The concentration of the electrolyte salt may be, for example, 0.1 mol / L, 2 mol / L, 4 mol / L, 6 mol / L, 8 mol / L, or 10 mol / L. The concentration of the electrolyte salt in the electrolyte solution of the magnesium battery may be in any combination of the above values.

[0048] According to the examples of the present application, within the above concentration range, the reaction efficiency of the anhydrous magnesium salt and the anhydrous lithium salt in the non-aqueous solvent is high, and the viscosity of the electrolyte is appropriate. 2+ When the concentration of the electrolyte salt is lower than 0.1 mol / L, the ion conductivity is low and the ohmic polarization of the battery is relatively large. When the concentration of the electrolyte salt is higher than 10 mol / L, the viscosity of the electrolyte increases, the mass transfer and diffusion of ions is inhibited, and the concentration polarization of the battery increases. Preferably, in some embodiments, the concentration of the electrolyte salt is 0.1 mol / L to 3 mol / L.

[0049] (Method of manufacturing electrolyte for magnesium batteries) On the other hand, in the present application: A method for producing an electrolyte for a magnesium battery, comprising: uniformly mixing anhydrous magnesium salt, anhydrous lithium salt, and a non-aqueous solvent; reacting the mixture at 25°C to 200°C for 3 to 48 hours; and cooling the mixture to -30°C to 25°C to obtain an electrolyte for a magnesium battery, The anhydrous magnesium salt is one or more selected from magnesium chloride, magnesium fluoride, magnesium bromide, magnesium iodide, magnesium bis(hexamethyldisilazide), magnesium bis(trifluoromethanesulfonyl)imide, and Grignard reagents; The anhydrous lithium salt is one or more selected from lithium chloride, lithium fluoride, lithium bromide, lithium iodide, lithium bis(trimethylsilyl)amide, and lithium bis(trifluoromethanesulfonyl)imide; A method for producing an electrolyte for a magnesium battery is further provided.

[0050] According to the embodiment of the present application, the manufacturing process of the electrolyte for magnesium batteries must be carried out in a glove box filled with inert gas and with a water content of <0.1 ppm and an oxygen gas content of <0.1 ppm, in order to prevent the electrolyte from being interfered with by water, oxygen gas or carbon dioxide, and in this process, anhydrous magnesium salt, anhydrous lithium salt and non-aqueous solvent form aggregates with a cluster structure.

[0051] In certain embodiments, the inert gas is at least one of helium gas and argon gas.

[0052] In some embodiments, the molar ratio of the anhydrous magnesium salt to the anhydrous lithium salt is 1:(0.1-4). For example, the molar ratio of the anhydrous magnesium salt to the anhydrous lithium salt may be 1:0.1, 1:1, 1:2, 1:3, or 1:4. The molar ratio of the anhydrous magnesium salt to the anhydrous lithium salt may range between any combination of the above ratios.

[0053] According to the embodiment of the present application, the Lewis acid-base reaction in the complexing agent of inorganic magnesium salt and inorganic lithium salt is a reversible reaction. Setting the mole number of anhydrous magnesium salt smaller than the mole number of anhydrous lithium salt is favorable for shifting the reversible reaction to the direction of producing electrolyte salt, thereby improving the production efficiency of the electrolyte salt.

[0054] The manufacturing method of the electrolyte for the magnesium battery according to the embodiment of the present application is simple, and the electrolyte of the manufactured magnesium battery has good mutual solubility, the system is stable, and has strong water resistance and resistance to impurity interference. Co-precipitation phenomenon between magnesium and other metals does not occur, thereby improving the battery performance of the magnesium battery.

[0055] (Magnesium battery) In yet another aspect of the present application, there is further provided a magnesium battery comprising a positive electrode, a separator, a negative electrode, and an electrolyte of the magnesium battery according to any one of the embodiments of the first aspect of the present application.

[0056] In some embodiments, the positive electrode includes a positive electrode active material, a conductive agent, a current collector, and a binder. The positive electrode active material may be an inorganic transition metal oxide, sulfide, or boride, and preferably, the positive electrode active material is Mo6S8.

[0057] In some embodiments, the separator comprises an organic polymer membrane, a conductive agent, a catalyst, and a binder.

[0058] In some embodiments, the negative electrode comprises an active negative electrode material and a binder. The active negative electrode material comprises at least one of magnesium metal and a magnesium alloy.

[0059] The magnesium battery according to the embodiment of the present application contains the electrolyte of the magnesium battery according to any one of the embodiments of the first aspect, and therefore has good stability, relatively strong water and impurity resistance, and excellent electrochemical performance due to the synergistic effect of each component, and can promote reversible precipitation and dissolution of magnesium, reduce overvoltage, inhibit magnesium salt from forming a passivation layer on the anode surface, and improve the charge / discharge specific capacity and cycle stability of the magnesium battery. In view of this, the magnesium battery according to the embodiment of the present application can be applied to energy storage power supply systems such as hydroelectric, thermal, wind and solar power plants, as well as multiple fields such as power tools, military equipment, and aerospace. EXAMPLES

[0060] The following examples are provided to more specifically illustrate the disclosed contents of the present application, and these examples are merely illustrative, since it will be apparent to those skilled in the art that various modifications and variations can be made within the scope of the disclosed contents of the present application. Unless otherwise specified, all parts, percentages, and ratios reported in the following examples are by weight, all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and all equipment used in the examples are commercially available.

[0061] Example 1 Preparation of magnesium battery electrolyte: In a glove box with oxygen and water contents of less than 1 ppm and filled with argon gas, 0.3 mol / L anhydrous magnesium chloride (MgCl2), 0.15 mol / L anhydrous lithium hexamethyldisilazide (LiHMDS) and tetrahydrofuran were mixed and reacted at 25°C for 24 hours, and then cooled to 25°C to obtain a magnesium battery electrolyte.

[0062] Example 2 Preparation of magnesium battery electrolyte: In a glove box with oxygen and water contents of less than 1 ppm and filled with argon gas, 0.3 mol / L anhydrous magnesium chloride (MgCl2), 0.15 mol / L anhydrous lithium hexamethyldisilazide (LiHMDS), 0.1 mol / L anhydrous lithium chloride (LiCl) and tetrahydrofuran were mixed and reacted at 25°C for 24 hours, and then cooled to 25°C to obtain a magnesium battery electrolyte.

[0063] Comparative Example 1 Preparation of magnesium battery electrolyte: In a glove box with oxygen and water contents less than 1 ppm and filled with argon gas, 0.3 mol / L anhydrous magnesium chloride (MgCl2), 0.1 mol / L anhydrous lithium chloride (LiCl) and tetrahydrofuran were mixed and reacted at 25°C for 24 hours, and then cooled to 25°C to obtain magnesium battery electrolyte.

[0064] (Measurement part) Measurement of Raman spectrum of electrolyte of magnesium battery: The electrolyte was sealed in a quartz tube and measured using a He-Ne laser (632.817 nm) to obtain the Raman spectrum of the electrolyte.

[0065] Nuclear magnetic resonance measurements of magnesium battery electrolyte: 7 Li NMR (155,50 MHz, d8-THF, 298K, standard sample is 1M LiCl / D2O solution).

[0066] Cyclic voltammetry measurements for the precipitation and dissolution of metallic magnesium: Carbon paper was used as the working electrode, magnesium sheet as the counter electrode and reference electrode, and a Mg / C battery was assembled to carry out cyclic voltammetry tests. Here, the scan rate was 25 mV / s.

[0067] Measurement of linear scan of precipitation and dissolution of metallic magnesium: A Mg / C cell was assembled with carbon paper as the working electrode and magnesium sheet as the counter and reference electrodes to carry out cyclic voltammetry tests, where the scan rate was 25 mV / s.

[0068] Magnesium battery test: Mo6S8 positive electrode, electrolyte, separator, and magnesium sheet negative electrode are installed in order to complete the production of magnesium full cell. Constant current charge and discharge test is performed on the battery, the voltage range of the battery test is 0.2~2.0V, and the rate of the battery test is 31.1C.

[0069] Since the results of the interaction between MgCl2 and LiCl have been proven and published, the interaction between MgCl2 and LiHMDS is characterized in Figures 1 and 2. As can be seen from Figures 1 and 2, the peak position of the Raman spectrum of the electrolyte salt of the magnesium battery in Example 1 of this application is 619 cm -1 and the electrolyte salt is [Mg m Li n X o (HMDS) 2m+n-o R p ]·M q It has been demonstrated that an electrolyte for magnesium batteries has been successfully synthesized.

[0070] In order to test the magnesium precipitating and dissolving performance of the electrolyte of the magnesium battery, the cyclic voltammetry curves of the electrolytes of Example 2 and Comparative Example 1 were measured with and without interference to the electrolyte.

[0071] As can be seen from FIG. 3, magnesium ions begin to precipitate at 0.4V, and magnesium ions begin to dissolve at the oxidation peak of 0.1V. As can be seen from FIG. 4, when impurity interference exists in the electrolyte of the magnesium battery, the precipitation potential of magnesium is 0.6V, and the dissolution potential is 0.1V. Therefore, even when impurity interference exists in this electrolyte, it is still possible to achieve reversible precipitation and dissolution of magnesium, which indicates that this electrolyte has good impurity resistance. The cyclic voltammetry curve of the magnesium battery electrolyte manufactured in a glove box with a water content of 1000 ppm for precipitating and dissolving magnesium is shown in FIG. 5, with a magnesium precipitation potential of 0.5V and a dissolution potential of 0.1V. Therefore, even when the water content is high, this electrolyte can achieve reversible precipitation and dissolution of magnesium, which indicates that this electrolyte has good water resistance and stability. On the other hand, as can be seen from FIGS. 6 and 7, when the LiHMDS salt was not present in the electrolyte of Comparative Example 1, no redox peaks were observed that caused the precipitation and dissolution of metallic magnesium, indicating that the LiHMDS salt is an important factor in providing the electrolyte with water resistance.

[0072] In addition, as can be seen from the linear scanning curve in FIG. 8, the electrochemical window of the electrolyte of the magnesium battery in Example 2 is 2.8 V (vs. Mg 2+ / Mg), indicating that the electrochemical window of this electrolyte is wide and its performance is excellent.

[0073] In order to test the application of the magnesium battery electrolyte in Example 2 to a magnesium ion battery, a charge / discharge performance test was performed on the Mg / Mo6S8 battery, and the test results are shown in Figures 9 and 10. The test results show that the initial discharge specific capacity of the magnesium battery assembled with the magnesium battery electrolyte in the example of this application is about 105 mAh g -1 The specific capacity after 10,000 cycles is approximately 83 mAh g -1 It was demonstrated that this magnesium battery exhibits good specific charge / discharge capacity and stable cycle performance.

[0074] As described above, the addition of the electrolyte salt and non-aqueous solvent provides the electrolyte of the magnesium battery with good stability, relatively strong resistance to water and impurities, and excellent electrochemical performance, thereby imparting high charge / discharge specific capacity and cycle performance to the magnesium battery.

[0075] The above are only specific embodiments of the present application, and the scope of protection of the present application is not limited thereto, and those skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and all such modifications or replacements should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be consistent with the scope of protection of the claims.

Claims

1. An electrolyte for a magnesium battery comprising a non-aqueous solvent and an electrolyte salt, the non-aqueous solvent is one or more selected from the group consisting of imidazole-based ionic liquids, pyrrole-based ionic liquids, piperidine-based ionic liquids, ether-based compounds, ester-based compounds, pyridine-based compounds, nitrile-based compounds, sulfone-based compounds, and ketone-based compounds; The chemical formula of the electrolyte salt is [Mg ｍ Li ｎ X ｏ (HMDS) ２ｍ＋ｎ－ｏ R ｐ ]・M ｑ and The X is selected from a halogen ion and / or a bistrifluoromethanesulfonylimide ion; The HMDS represents hexamethyldisilazane ion, R is one or more groups selected from an alkyl group, a fluoroalkyl group, and an aryl group, M is a non-aqueous solvent molecule complexing agent; The m is an integer selected from 1 to 6, the n is an integer selected from 1 to 6, the o is an integer selected from 1 to 6, the p is an integer selected from 0 to 6, and the q is an integer selected from 1 to 20. Magnesium battery electrolyte.

2. The imidazole-based ionic liquid is selected from 1-ethyl-3-methylimidazolium tetrafluoroborate and / or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonic acid)imide salt; The pyrrole-based ionic liquid is selected from N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide salts; The piperidine-based ionic liquid is selected from N-butyl-N-methylpiperidinium bis(trifluoromethanesulfonyl)imide salts; The electrolyte for a magnesium battery according to claim 1.

3. the ether-based compound is one or more selected from tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dioxane, and polyethylene glycol dimethyl ether; The ester compound is selected from ethyl acetate; The pyridine-based compound is selected from pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,6-dichloropyridine, and 2-aminopyridine; The nitrile compound is selected from acetonitrile; The sulfone-based compound is selected from dimethyl sulfoxide; The electrolyte for a magnesium battery according to claim 1.

4. The non-aqueous solvent is tetrahydrofuran, and the halogen ion is a chloride ion. The electrolyte for a magnesium battery according to claim 1.

5. wherein p is 1, 2, 3, 4, 5, or 6; The electrolyte for a magnesium battery according to claim 1.

6. A method for producing an electrolyte for a magnesium battery, comprising the steps of: uniformly mixing anhydrous magnesium salt, anhydrous lithium salt, and a non-aqueous solvent; reacting the mixture at 25°C to 200°C for 3 to 48 hours; and cooling the mixture to -30°C to 25°C to obtain the electrolyte for a magnesium battery according to claim 1, The anhydrous magnesium salt is one or more selected from magnesium chloride, magnesium fluoride, magnesium bromide, magnesium iodide, bis(hexamethyldisilazide)magnesium, bis(trifluoromethanesulfonyl)imide magnesium, and Grignard reagents; the anhydrous lithium salt is selected from lithium bis(trimethylsilyl)amide and a second anhydrous lithium salt; The second anhydrous lithium salt is one or more selected from lithium chloride, lithium fluoride, lithium bromide, lithium iodide, and lithium bis(trifluoromethanesulfonyl)imide; A method for producing electrolyte for magnesium batteries.

7. the molar ratio of the anhydrous magnesium salt to the anhydrous lithium salt is 1:(0.1-4); A method for producing the electrolyte for a magnesium battery according to claim 6.

8. The concentration of the electrolyte salt is 0.1 to 10 mol / L. A method for producing the electrolyte for a magnesium battery according to claim 6.

9. The concentration of the electrolyte salt is 0.1 to 3 mol / L. A method for producing the electrolyte for a magnesium battery according to claim 6.

10. A magnesium battery comprising a positive electrode, a separator, a negative electrode, and the electrolyte solution of any one of claims 1 to 9. Magnesium battery.

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