WO2015152469A1 - Electrolyte for magnesium secondary battery, and magnesium secondary battery comprising same - Google Patents

Abstract

Provided are an electrolyte for a magnesium secondary battery, and a magnesium secondary battery comprising the aforementioned electrolyte, the electrolyte comprising: a first electrolyte including a magnesium salt, 1,2-dimethoxyethane, and a glyme-based organic solvent represented by chemical formula 1; and a second electrolyte which is in the form of a layer located on the surface of an anode and comprises a polymer and a Grignard derivative, the Grignard derivative being a reaction product of a Lewis base represented by chemical formula 2 and a Lewis acid represented by chemical formula 3. An explanation for chemical formula 1 to chemical formula 3 exists in the detailed description.

Description

 【Specification】

 [Name of invention]

 Electrolyte for magnesium secondary battery and magnesium secondary battery containing same [Technical field]

 It relates to an electrolyte for a magnet secondary battery and a magnet secondary battery comprising the same.

 Background Art

Background Art With the miniaturization of personal computers, video cameras, mobile phones, and the like, in the fields of information-related devices and communication devices, lithium secondary batteries have become practical and widely used as power supplies for these devices. This lithium secondary battery generally has a positive electrode using a lithium transition metal oxide such as LiCo0 ₂ as a positive electrode active material, a negative electrode using metal lithium, a carbon material or the like as a negative electrode active material, and a lithium salt as a supporting salt, which is an organic solvent. It consists of the electrolyte solution melt | dissolved in the. Lithium released from the positive electrode is occluded in the negative electrode at the time of layer charge, and lithium separated from the negative electrode is occluded in the positive electrode at the time of discharge. That is, it is a rocking chair type secondary battery which uses lithium as a carrier.

This lithium secondary battery has advantages of high operating voltage and high energy density because the metal lithium or carbon material used as the negative electrode active material has a low reaction potential with lithium and a nonaqueous electrolyte is used for the electrolyte. Its use is rapidly expanding as a power source for small portable devices. However, lithium, which is a carrier of a lithium secondary battery, is very active, and there is a risk of burning in response to moisture in the air, for example. This point in the manufacturing process of a lithium secondary battery requires sufficient consideration, such as a dry environment without moisture, and also leads to the increase of manufacturing cost.

 In the lithium secondary battery, when lithium metal is used as the negative electrode, dendrite (needle crystal) precipitates along with charge and discharge reaction, and the dendrites penetrate through the separator, causing a short circuit, and the solvent and the like burn. There is. Therefore, there is a desire for a new type of rocking chair type secondary battery in which a material for a carrier is changed.

 In addition, there is a problem that the confirmed reserve amount of lithium is as low as about 11 million tons, and the ubiquity is high. Therefore, in order to supply secondary batteries for large-capacity power supplies in the future, it is assumed that battery materials necessary for mass supply can be secured in consideration of the amount of material used for the batteries. In addition, it is considered that it is desirable to select a material that is more stable in raw material supply and that is less likely to change in price.

 Accordingly, attention has been paid to resource-rich magnets, and development of storage batteries, that is, magnesium secondary batteries using them as materials for secondary batteries is gradually progressing at home and abroad. Magnesium is cheaper than lithium, about two-thirds the amount of lithium, but has a high capacitance density (2.21 Ah / kg).

By bringing the performance of the magnesium secondary battery closer to the lithium ion battery, It is possible to reduce the battery cost per capacity.

 Magnesium secondary batteries have excellent safety and price competitiveness, but due to their low layer discharge reversibility, new electrode materials and electrolytes need to be developed to overcome them.

 [Detailed Description of the Invention]

 [Technical problem]

 One embodiment of the present invention is to provide a double layer electrolyte having excellent electrochemical oxidation resistance, maximizing dissociation and mobility of magnesium ions to realize high subsequent conductivity, and improved reversibility of electrochemical oxidation / reduction reaction.

 Another embodiment of the present invention is to provide a magnet secondary battery comprising the electrolyte for the magnesium secondary battery.

 Technical Solution

 In one embodiment of the present invention, the first electrolyte comprising a magnesia salt, 1,2 ᅳ dimethicetane, and a glyme-based organic solvent represented by the formula (1); And a Grignard derivative, which is a reaction product of a polymer and a Lewis base represented by Formula 2, and a Lewis acid represented by Formula 3, and comprises a second electrolyte in the form of a layer located on the surface of the cathode. Provided is a battery electrolyte.

[Formula 1]

 [Formula 2]

R ³ _a MgCl ₂ - _a

 [Formula 3]

R ⁴ _b AlCl ₃ -b

 In Chemical Formulas 1 to 3,

R ¹ and R ² are each independently a substituted or unsubstituted C2 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a combination thereof,

 n is an integer from 2 to 5,

R ³ and R ⁴ are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a combination thereof,

 a is an integer of 0 to 2,

 b is an integer of 0-3.

 The Grignard derivative may be a compound represented by the following Formula 4.

[Formula 4]

(R ³ _a MgCl ₂ -a) ₂ -AlCl ₃

 In Chemical Formula 4,

R ³ is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 aryl group or a combination thereof,

 a is an integer of 0-3.

 The Grignard derivative may be a compound represented by the following Formula 5. [Formula 5]

Mg (AlCl ₄ -b ⁴ b) ₂

 In Chemical Formula 5,

R ⁴ is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted ¾ C6 to C30 aryl group, or a combination thereof, ^"

 b is an integer of 0-3.

R ¹ and R ² may be each independently a substituted or unsubstituted C2 to C20 alkyl group.

 The glyme organic solvent may be diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or a combination thereof.

 The glyme-based organic solvent may include 1,2—dimethoxyethane and the solvent represented by Chemical Formula 1 in a volume ratio of 1 to 99:99 to 1. The glyme-based organic solvent may include 1,2-dimethicethane and diethyleneglycol dimethyl ether.

The glyme-based organic solvent may include the 1,2-dimethoxyethane and the diethylene glycol dimethyl ether in a volume ratio of 1 to 90:90 to 1. All.

 The glyme organic solvent may be included in an amount of 80 to 99 wt% based on the total amount of the magnesium secondary battery electrolyte.

The magnesium salt is, magnesium bis (trifluoromethanesulfonyl) limide (Mg (TFSI) 2), magnesium bis (hexafluorophosphate) ^* -Mg (PF ₆ ) ₂ ), magnesium bis (perchlorate): Mg (C10 ₄ ) 2), magnesium bis (trifluoromethanesulfonyl) imide: Mg ( CF ₃ S0 ₃ N) ₂ ), magnesium bis (oxalato) borate (Mg (B0B) ₂ ), magnesium bis (tetrafluoroborate): mgium (tetrafluoroborate): Mg ( BF ₄ ) ₂ ), magnesium bis (perfluoroethanesulfonyl) imide: Mg (BETI) ₂ ), magnesium trifluoromethanesulfonate: Mg (CF3S03) 2 ) Or a combination thereof.

 The concentration of the magnesium salt may be 0.05 to 1.0M.

The polymer and the compound represented by Chemical Formula 2 or 3 may include 10 to 50 wt% of the polymer and 50 to 90 wt% of the compound represented by Chemical Formula 2 or 3, specifically 20 based on the total amount of the electrolyte 12. To 30% by weight, and 70 to 80% by weight. The thickness of the second electrolyte may be 1 to 10, specifically 3 to 6.

 The polymer is vinylidene fluoride-nucleus fluoropropylene copolymer (HFP as PVDF-c, HFP content: 6-15% by weight), polyvinylidene fluoride (PVDF), polyvinylacetate (PVAc), polymethyl meta Acrylate (PMMA), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyethylene oxide (PEO), or a combination thereof. The weight average molecular weight (Mw) of the polymer may be 100, 000 to 600, 000, specifically, 400, 000 to 450, 000.

 In another embodiment of the present invention, an electrolyte according to an embodiment of the present invention described above; anode; And it provides a magnesium secondary battery comprising a negative electrode.

 Advantageous Effects

 Excellent electrochemical oxidation resistance, maximize dissociation and mobility of magnesium and silver to realize high ionic conductivity, electrochemical oxidation / reduction reaction. It is possible to implement a magnesium secondary battery with improved reversibility.

 [Brief Description of Drawings]

 1 is a schematic view showing a magnet secondary battery according to one embodiment. Figure 2 is a schematic diagram showing the interaction between the organic solvent and the magnesium salt according to an embodiment of the present invention.

3 is diethylene glycol dimeth in an organic solvent according to an embodiment of the present invention. Schematic diagram showing the interaction between tilether and magnesium ions.

 4 shows a schematic view of a magnesium negative electrode including a second electrolyte according to an embodiment of the present invention.

 Figure 5 shows a schematic diagram for explaining the mechanism of action of the second electrolyte according to an embodiment of the present invention.

 6 is a graph showing the results of performing reactions for plating Mg on a copper electrode under constant current conditions of the solvents according to Comparative Examples 1 to 6. FIG. 7 is a graph showing a result of performing a reaction of plating Mg on a copper electrode under constant current conditions using the solvents according to Reference Examples 1 and Comparative Example 2. FIG.

 8 is a graph showing the results of performing the reaction of plating Mg on the copper electrode under the constant current conditions of Reference Examples 1 and 1, respectively.

 9 is a graph evaluating the electrochemical oxidative decomposition potential characteristics of the electrolyte according to Reference Example 1 with respect to Comparative Example 2.

10 is a graph evaluating specific capacity of Mo ₆ S ₈ / Mg cell according to Reference Example 1.

 <Explanation of symbols for main parts of the drawings>

 3: magnesium secondary battery

 4: electrode assembly

5: anode 6: cathode

 7 ： Separator

 8: Battery case

 11: cap plate

 101 ： magnesium cathode

102 ： oxide film (Mg0 / Mg (0H) ₂ )

 103 ： Second electrolyte (functional membrane: gr inard + po lymer)

 104 ： Solvent decomposition inhibition

 105 ： Smooth movement of magnesium ions

 [Best form for implementation of the invention]

 Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited, and the present invention is defined only by the scope of the claims to be described later. In the present specification, "combination thereof" means that two or more substituents are bonded to a linking group, or two or more substituents are condensed to each other unless otherwise defined.

 As used herein, an "alkyl (a lkyl) group" means a saturated aliphatic hydrocarbon group, unless otherwise defined.

The alkyl group may have 1 to 20 carbon atoms. Alkyl group is 1 to It may also be a medium alkyl group having 10 carbon atoms. The alkyl group may also be a lower alkyl group having 1 to 6 carbon atoms.

 For example, a C1 to C4 alkyl group has 1 to 4 carbon atoms in the alkyl chain, i.e., the alkyl chain is methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and t_butyl Selected from the group consisting of:

 Typical alkyl groups include methyl (methyl Mt), ethyl (ethyl, et), propyl, isopropyl, butyl (butyl, bu), isobutyl, t-butyl, pentyl, nucleus, ethenyl, propenyl, butenyl, cyclopropyl It means one or more substituents individually and independently selected from cyclobutyl, cyclopentyl, cyclonucleus and the like.

 The alkyl group may be branched, straight chain or cyclic.

"Aryl ryl) group" ¹ means an aryl group comprising carboxyaryl (eg phenyl) having at least one ring having a covalent pi electron field, which term is a polycyclic monocyclic or fused ring. Groups of clicks (ie rings having adjacent pairs of carbon atoms).

In the present specification, "substituted"'unless otherwise defined, an alkyl group having 1 to 30 carbon atoms, an alkylsilyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, and 2 to 2 carbon atoms C1-C10 trifluoroalkyl groups, such as a 30 heteroaryl group, a C1-C10 alkoxy group, a fluoro group, and a trifluoromethyl group, a C12-C30 carbazole group, and a C6-C30 An arylamine group, a substituted or unsubstituted aminoaryl group having 6 to 30 carbon atoms or a cyano group is meant.

In the present specification, "glyme-based solvent ¹ " means a glycol ether, unless otherwise defined, and includes a glycol solvent such as 1,2-dimethoxyethane and It means that it contains all of the diglyme-based solvent, such as diethylene glycol dimethyl ether.

 Magnesium secondary battery electrolyte according to an embodiment of the present invention may be a double-layer electrolyte containing a first electrolyte and a second electrolyte at the same time.

 The bilayer electrolyte according to an embodiment of the present invention may have a novel electrolyte composition excellent in oxidation resistance.

 The first electrolyte may include a magnesium salt, and a 1, 2-dimethicethane and a glycol-based organic solvent represented by the following Chemical Formula 1.

[Formula 1]

In Formula 1, R ¹ and R ² are each independently, substituted or unsubstituted

An alkyl group of C1 to C20, a substituted or unsubstituted cycloalkyl group of C3 to C20, a substituted or unsubstituted C6 to C30 aryl group, or a combination thereof, n is an integer of 2 to 5.

Specifically, R ¹ and R ² may be each independently a substituted or unsubstituted C2 to C20 alkyl group. C ² to which R ¹ and R ² are substituted or unsubstituted. In the case of an alkyl group of C 20, the organic solvent may be oriented so as to facilitate formation of a complex with a magnet cation in space. As a result, dissociation of magnesium ions can be achieved more effectively.

 Magnesium salts can be derived from Grignard reagents. The Grignard reagent is a strong reducing agent represented by the general formula RMgX (in THF) and has some difficulties in being used in a battery. First, the Grignard reagent has a problem of decomposing at the anode side due to its low electrochemical oxidation potential. In addition, the Grignard reagent has to use a highly volatile solvent such as tetrahydrofuran (THF). Can occur.

Thus, as in one embodiment of the present invention, a glycol solvent and diethylene glycol dimethyl ether such as 1,2-dimethicethane and diethylene glycol dimethyl ether _. When the organic solvent including the same diglyme-based solvent is included, a high-performance and high-safety electrolyte solution capable of efficiently inducing insertion / desorption reaction of magnesium ions of a magnet secondary battery can be prepared. When including such a high performance and high safety electrolyte, the magnet secondary battery can improve the reversibility of the electrochemical oxidation / reduction reaction of the magnesium metal anode and the performance of the full cell.

 The glyme solvent may have a low viscosity property to facilitate the mobility of ions.

In addition, the diglyme solvent may be an alkylene group, a cycloalkylene group, or Specific examples of the ether solvent in which the arylene group is connected to the ether group include diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or a combination thereof.

The diglyme solvent has a high boiling point and a high donor number. Since the diglyme solvent has a high boiling point, it is excellent in terms of stability of the battery because of the low internal pressure generated by volatile gases, and a high donor number is a magnet. Magnesium ions can be easily dissolved from the electrode, the dissolved ions can be reliably solvated, and the reduced reaction at the counter electrode interface can be reduced by moving the dissolved ions to the counter electrode. To advantageously perform. In other words, the process of dissolving the magnesium ions into magnet ions is called stripping, in which the resistance (overvoltage) to break the crystalline Mg-Mg binding force and oxidize to Mg ²⁺ ions appears as a voltage drop phenomenon. In order to oxidize Mg ^{2 +} ions into Mg ²⁺ ions by breaking the strong bonds, the solution structure has a high dissociation ability (excellent nucleophilicity) and a solution structure so that Mg ²⁺ ions can be stably maintained in the dissociated state. A solvent capable of forming an ion structure is required, and the diglyme solvent is suitable.

In particular, when a mixture of the glyme solvent and the diglyme solvent is used in combination, the mixed organic solvent acts complementarily to improve the reversibility of the electrochemical oxidation / reduction reaction of magnesium and also to secure battery safety. have. On the other hand, the donor number, a Lewis basicity, that is, a measure of the degree of dissolution of a cation or a Lewis acid in a solvent, for example, an antimony pentachlor ide (SbCl ₅ ), which is a Lewis base and a reference Lewis acid, is 1 The reference value is the enthalpy value when forming an adduct from 2-dichloroethane. The larger the absolute value of the enthalpy, the higher the donor number. On the other hand, the higher the donor number, the better the ability to dissolve the cation or Lewis acid.

 Specific examples of the glyme-based organic solvent include a mixed solvent of 1, 2-dimethoxy ethane and diethylene glycol dimethyl ether, a mixed solvent of 1, 2-dimethoxy ethane and triethylene glycol dimethyl ether, or 1, 2 It may include a mixed solvent of dimethicetane and tetraethylene glycol dimethyl ether, and most specifically, may be a mixed solvent of 1, 2-dimethicetane and diethylene glycol dimethyl ether.

The glyme organic solvent may include 1, 2-dimethicethane and a solvent represented by Formula 1 in a volume ratio of 1 to 99:99 to 1, preferably 10 to 90:90 Volume ratio of 10 to 10, more preferably 30 to 70: 70 to 30, and most preferably 1, 2-dimethicethane and diethylene glycol dimethyl ether in a volume ratio of 50:50. When the mixed volume ratio of the organic solvent is within the above range, dissociation and migration of magnesium ions may be optimized to maximize the reversibility of the electrochemical oxidation / reduction reaction of the magnet secondary battery. An effect of the glyme-based organic solvent represented by Chemical Formula 1 will be described with reference to FIG. 2.

 Figure 2 is a schematic diagram showing the interaction of the glyme (glyme) -based organic solvent and magnesium salt according to an embodiment of the present invention.

 Referring to FIG. 2, since the glyme-based organic solvent represented by Chemical Formula 1 may serve as an isu base and the magnesium ions derived from the magnesium salt may act as a Lewis acid, the Lewis base and the Lewis acid may be Ligand binding to each other. At this time, since the ether portion acts as an electron-pair donor in the glyme-based organic solvent represented by Formula 1, the longer the chain of the glyme-based organic solvent increases the ether portion capable of ligand binding, Due to this, the insertion / desorption reaction of reversible magnesium ions can occur more effectively.

 More specifically, the glyme organic solvent represented by Chemical Formula 1 may include diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or a combination thereof.

 The magnesium salt is magnesium bis (trifluoromethanesulfonyl) imide

bi s (tr if luoromethanesul fonyl) l imide: Mg (TFSI) ₂ ), magnesium bis (hexaf 1 uor ophosphat e): Mg (PF ₆ ) 2), magnesium bis (Magnesium bis (perchlorate) ： Mg (C10 ₄ ) ₂ ), magnesium bis (trif luoromethanesulfonyDimide ^' -Mg (CF ₃ S0 ₃ N) 2), magnesium bis (oxalato) borate (magnesium bis ( oxalato) borate (Mg (B0B) ₂ ), magnesium bis (tetrafluoroborate Kmagnesium bis (tetraf luoroborate): Mg (BF ₄ ) ₂ ), magnesium bis (perfluoroethanesulfonyl) imide (magnesium bis ( perf luoroethanesulfonyl) imide: Mg (BETI) 2), magnesium trifluoromethanesulfonate: Mg (CF3S0 ₃ ) 2), or a combination thereof, most specifically magnesium bis (tri) Fluoromethanesulfonyl) imide (magnesium)

bis (trif luoromethanesulfonyDlimide: Mg (TFSI) ₂ ). When using the magnet salt, there is an effect that does not form an oxide film that prevents ion permeation on the surface of the magnesium electrode and does not corrode the positive electrode current collector.

 The glyme-based organic solvent may be 80 to 99% by weight, and specifically 80 to 95% by weight based on the total amount of the electrolyte for the magnet secondary battery. When the organic solvent is within the above range, it is possible to effectively dissociate the magnesium salt and to help dissociate the magnesium ions smoothly under an electric field.

The concentration of the magnesium salt may be 0.05 to 1.0M. Of magnesium salts When the concentration is within the above range, high ion conductivity can be obtained. The glyme-based organic solvent may further include a general organic solvent.

 Specific examples of the organic solvent include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, dipropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxy ethane, diepoxyethane, It may be any one selected from the group consisting of vinylene carbonate, sulfolane, gamma-butyrolactone, propylene sulfite and tetrahydrofuran, or a mixture of two or more thereof, but is not limited thereto.

 The second electrolyte may include a polymer and a Grignard derivative which is a reaction product of a Lewis base represented by Formula 2 and a Lewis acid represented by Formula 3 below.

 [Formula 2]

R ³ _a MgCl ₂ - _a

 [Formula 3]

R ⁴ bAlCl ₃ - _b

In Formulas 2 and 3, R ³ and R ⁴ are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 aryl group or a combination thereof, a is an integer of 0 to 2 And b is an integer of 0-3. The Grignard derivative may be a compound represented by the following Formula 4.

[Formula 4]

(R ³ _a MgCl ₂ - _a ) 2-AlCl ₃

In Formula 4, R ³ is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 aryl group or a combination thereof, and a is an integer of 0 to 3.

 The Grignard derivative may be a compound represented by the following Formula 5. [Formula 5]

In Formula 5, R ⁴ is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 aryl group or a combination thereof, b is an integer of 0 to 3.

In the case of a magnet secondary battery, the formation of an oxide film (MgO / Mg (OH) ₂ ) on the surface of the negative electrode is inevitable due to oxidation of the magnesium negative electrode. Since an oxide film is formed on the surface of the cathode, dissociation of magnesium silver at the cathode is disturbed, thereby reducing the reversibility of the electrochemical oxidation / reduction reaction of the magnet cathode.

In the present invention, a second electrolyte, which is a functional membrane for smooth dissolution of magnesium cations from the magnesium cathode, may be introduced on the surface of the magnesium anode to improve the reversibility of the electrochemical oxidation / reduction reaction of the magnetite cathode. . The mechanism of action of the second electrolyte will be described below in detail with reference to FIGS. 4 and 5.

 4 shows a schematic view of a magnesium negative electrode including a second electrolyte according to an embodiment of the present invention.

 Referring to FIG. 4, the magnesium anode according to the embodiment of the present invention may include a second electrolyte that functions as a functional film on the surface of the magnet cathode. The functional membrane may include a polymer, thereby physically separating the magnesium anode and the U-electrolyte, and may function as a support including a Grignard derivative.

 5 is a schematic view for explaining the mechanism of action of the second electrolyte.

Referring to FIG. 5, by introducing the second electrolyte, the U-electrolyte and the magnet cathode are physically separated, so that reaction between the organic solvent and the cathode included in the first electrolyte is suppressed, and an oxide film (MgO / Mg) is formed on the surface of the magnesium cathode. (OH) ₂ ) can be suppressed, and by effectively removing the formed oxide film (MgO / Mg (OH) ₂ ), it is possible to easily cause dissolving ion (dissolut ion, str ipping) from the magnesium cathode. It can be seen that.

In particular, the Grignard derivative which is a reaction product of the Lewis base represented by Formula 2 and the Lewis acid represented by Formula 3 may include a compound represented by Formula 4. Compound represented by the formula (4), substituted or unsubstituted C1 to C20 alkyl group, substituted or unsubstituted C6 to C30 Lewis acid (b = 0) which is not substituted with an aryl group or the like is reacted with a Lewis base substituted with a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 aryl group, or the like.

 As another specific example of the Grignard derivative, a compound represented by the formula (5) may be mentioned. The compound represented by the formula (5) is substituted or unsubstituted C1 to C20 alkyl group, substituted or unsubstituted C6 to C30 aryl group substituted or unsubstituted C1 to C20 alkyl group, substituted or unsubstituted To a Lewis base (a = 0) unsubstituted with a substituted C6 to C30 aryl group or the like.

Specific examples of the Lewis base include Grignard reagent, and specific examples of the Lewis acid include AlCl ₂ Et, A1C1 ₃₎ BPh ₃ , and the like.

 By controlling the mixing ratio of the Lewis base and the Lewis acid, Grignard derivatives having various compositions can be prepared.

The specific examples of the Grignard derivative, PhMgCl solution (Lewis base) and A1C1 ₃ solution (Lewis acid), a 2: 1 mole ratio which can be a product of (PhMgCl) ₂ -AlCl ₃ banung to the.

 Furthermore, the compound represented by following formula (5-1) is mentioned.

[Formula 5-1]

 The polymer and the Grignard derivative included in the second electrolyte include 10 to 50% by weight of the polymer, and 50 to 90% by weight of the Grignard derivative, specifically 20 to 30% by weight, based on the total amount of the second electrolyte. It may be included as. When the content of the polymer and the Grignard derivative is as described above, it is possible to obtain a high reversibility of the magnetic stripping (str ipping) and plating (pl at ing) effect.

 The thickness of the second electrolyte may be 1 to 10, specifically 3 to 6.

 When the thickness of the second electrolyte is as described above, resistance may be minimized in dissolving magnesium silver from the magnet anode and moving toward the anode.

The polymer is specifically, vinylidene fluoride-nucleus fluoropropyl tencopolymer (PVDF-co-HFP, HFP content: 6-15% by weight), polyvinylidene fluoride (PVDF), polyvinylacetate (PVAc), Polymethylmethacrylate (PMMA), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyethylene oxide (PEO), or a combination thereof. The weight average molecular weight (Mw) of the polymer may be 100, 000 to 600, 000. Another embodiment of the present invention provides a magnet secondary battery including the electrolyte, the positive electrode, and the negative electrode.

 Since the electrolyte is the same as the embodiment of the present invention described above, a description thereof will be omitted.

 The positive electrode may include a current collector, a positive electrode active material layer, and the positive electrode active material layer may include a conductive material, a binder, and / or a positive electrode active material.

 The cathode of the magnet secondary battery according to one embodiment of the present invention may be manufactured by a manufacturing method commonly used in the art. For example, a positive electrode may be prepared by mixing and stirring a binder, a solvent, and a conductive material and a dispersant in a positive electrode active material, if necessary, and then applying the same to a current collector and compressing the positive electrode.

As the cathode active material, a transition metal compound or a magnet composite metal oxide capable of inserting / demounting magnet ions may be used. Examples of transition metal compounds include oxides, sulfides or halides such as scandium, ruthenium, titanium, vanadium, molybdenum, chromium, manganese, iron, cobalt, nickel, copper, zinc, and more specifically, TiS ₂ , ZrS ₂₎ Ru0 ₂ , C03O4, Mo ₆ S ₈ , V ₂ 0 _5, etc. may be used, but is not limited thereto. In addition, examples of magnesium composite metal oxides include Mg ^ — _x A _x ) 0 ₄ (0 <x <0.5, Μ is Ni, Co, Mn, Cr, V, Fe, Cu or Ti, and A is Al, B, Si , Cr, V, C, Na, K or Mg) may be used a magnesium compound.

Vinylidene fluoride-nucleus fluoropropylene as the binder Copolymer (PVDF-co-HFP), polyvinyl idenef luor ide, polyacrylonitrile, polymethylmethacrylate

Various kinds of binder polymers, such as (polymethylmethacrylate), can be used. Conductive carbon is commonly used as the conductive material, and for example, various conductive carbon materials such as alum, carbon black acetylene black, caten black, denka black, super-P, and carbon nanotubes may be used. .

 The negative electrode may include a current collector, and / or a negative electrode active material. Alternatively, the cathode may use a metal such as a magnet as the counter electrode.

^"The negative electrode active material layer may include a conductive material, a binder, and / or a negative electrode active material.

 The negative electrode active material may be oxidized to generate magnesium ions. The negative active material may include at least one selected from the group consisting of a single material of magnesium and an alloy containing magnesium.

 The negative electrode active material and / or the negative electrode may be, for example, magnesium foil.

 As another example, the negative electrode may further include a binder and / or a conductive agent that is the same as or similar to that used to prepare the positive electrode.

As the separator, conventional inorganic separators or organic separators conventionally used as separators may be used. A glass filter may be used as the inorganic separator, and a porous polymer film may be used as the organic separator. have.

 The porous polymer film is a porous polymer made of a polyolefin-based polymer such as, for example, ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer. It is possible to use these or by laminating them.

 When the positive electrode and the negative electrode are prepared, a magnesium secondary battery may be manufactured by interposing a separator between the positive electrode and the negative electrode and including an electrolyte.

 The battery case used in one embodiment of the present invention can be adopted that is commonly used in the art, there is no limitation on the appearance according to the use of the battery, for example, cylindrical, square, pouch using a can (pouch) ) Or coin type.

[Form for implementation of invention]

 The following presents specific embodiments of the present invention. However, the embodiments described below are merely for illustrating or explaining the present invention in detail, and thus the present invention is not limited thereto.

In addition, the description is not described herein, so those skilled in the art can sufficiently infer technically, so the description thereof will be omitted. Example Reference Example 1

 (Production of electrolyte)

 0.3M Mg (TFSI) 2 (magnesiumbis (trifluoromethanesulfonyl) imide), 1,2-dimethoxyethane and diethylene glycol dimethyl ether were added in a volume ratio of 1: 1 to add an organic solvent. Prepared. At this time, the organic solvent was 82.5% by weight based on the total amount of the electrolyte.

(Production of magnesium secondary battery)

A positive electrode slurry was prepared by mixing Mo ₆ S ₈ , super-P carbon powder, and polytetrafluoroethylene (PTFE: polytetrafluoroethylene) in a 7: 2: 1 weight ratio.

 The cathode slurry was cast on a copper (Cu) mesh and then rolled to prepare a cathode.

 Magnesium metal disc (GoodFellow, 99.9%) was used as the cathode.

 Polyethylene having a thickness of 25 (43% porosity) was used as the separator.

 A magnesium secondary battery was manufactured using a coin type cell 2016 including the electrolyte, the cathode, the cathode, and the separator.

 Example 1

(Manufacture of polymer film) A vinylidene fluoride-nucleus fluoropropylene copolymer (HFP as PVDF-c, weight average molecular weight (Mw): 400,000, manufactured by Sigma Aldrich) and tetrahydrofuran were prepared in a mixture of 1 to 10 by weight ratio. .

A polymer solution was prepared by adding a mixed solution of 0.4M A1C1 ₃ and 0.8M PhMgCl in a weight ratio of 1: 3 to the mixture.

 (Introduction of Polymer Subtitle)

 After dispersing the polymer solution evenly on the surface of the magnesium metal disk of Reference Example 1, it was left at room temperature for about 10 minutes to evaporate the solvent tetrahydrofuran to introduce a polymer film on the surface of the magnesium metal disk.

 (Production of magnesium secondary battery)

 Instead of using a magnesium metal disk as a negative electrode, a magnesium secondary battery was manufactured in the same manner as in Reference Example 1 except that the magnesium metal disk on which the polymer film was introduced was used as a negative electrode. Comparative Example 1

 In Reference Example 1, a magnesium secondary battery was manufactured in the same manner as in Reference Example 1, except that a 1,2-dimethicethane solvent was used instead of the mixed organic solvent.

 Comparative Example 2

In Reference Example 1, instead of the mixed organic solvent, diethylene glycol dimethyl A magnesium secondary battery was manufactured in the same manner as in Reference Example 1, except that an ether solvent was used.

 Comparative Example 3

 In Reference Example 1, except that a triethylene glycol dimethyl ether solvent was used instead of the mixed organic solvent, a magnet secondary battery was manufactured in the same manner as in Reference Example 1.

 Comparative Example 4

 In Reference Example 1, except that a tetraethylene glycol dimethyl ether solvent was used instead of the mixed organic solvent, a magnet secondary battery was manufactured in the same manner as in Reference Example 1.

 Comparative Example 5

 In Reference Example 1, except that acetonitrile solvent was used instead of the mixed organic solvent, a magnesium secondary battery was manufactured in the same manner as in Reference Example 1.

 Comparative Example 6

 In Reference Example 1, except that a tetrahydrofuran solvent was used instead of the mixed organic solvent, a magnesium secondary battery was manufactured in the same manner as in Reference Example 1.

 Evaluation 1: Characterization of Solvents (1)

Table 1 shows the boiling point and donor number of each solvent included in Comparative Examples 1 to 6 It is shown.

상기 표 1을 참고하면， 1,2-디메특시에탄의 경우 도너 넘버가 높고， 디 에틸렌글리콜디메틸에테르의 경우 비점이 높음을 알 수 있다. 즉， 상기 흔합 유기용매에서 1,2-디메특시에탄은 마그네슘 이은의 해리를 용이하게 하고 동시 에 디에틸렌글리콜디메틸에테르는 용해된 이온을 안정적으로 보호하여 상대 전 극 계면에서 환원 반웅을 유리하게 수행할 수 있도록 함을 알 수 있다. 평가 2: 용매의 특성 평가 (2)—율특성 TABLE 1

Referring to Table 1, it can be seen that the donor number is high in the case of 1,2-dimethicethane, and the boiling point is high in the case of diethylene glycol dimethyl ether. That is, in the mixed organic solvent, 1,2-dimethicethane facilitates dissociation of magnesium silver, and at the same time, diethylene glycol dimethyl ether stably protects dissolved ions to advantageously reduce reaction at the counter electrode interface. It can be seen that it can be done. Evaluation 2: Characterization of Solvents (2) —Rate Properties

 The solvent according to Comparative Examples 1 to 6 was applied to a magnet / copper half cell (2016 type half cell, Welcos) and subjected to constant current cycling at 0.025C, and the result is shown in FIG. 6.

FIG. 6 is a graph showing the results of performing reactions in which Mg is plated on a copper electrode under constant current conditions using solvents according to Comparative Examples 1 to 6. FIG. Constant current cycling evaluation involves placing a magnesium disk (1T) on one side of the coin cell. The other side was welded with a disk-shaped 16pi copper electrode, and the electrolyte was added to assemble the cell.

 Referring to FIG. 6, it was confirmed that the plating of magnesium effectively occurred on the surface of the copper electrode while the solvent according to Comparative Example 1 exhibited a very low overvoltage near 0V during constant current cycling. In other words, it can be seen that 1,2-dimethicethane easily dissociates magnesium ions from the magnesium electrode in the electrolyte. Evaluation 3: Evaluation of Rate Characteristics of Electrolyte

 The electrolytic solution prepared in Reference Example 1 and Comparative Example 2 was applied to a magnet / magnet symmetric battery (2032 type half cell, Welcos) to perform constant current cycling at C / 3, C / 2, 1C, and 2C. It carried out and the result is shown in FIG.

 FIG. 7 is a graph showing the results obtained by performing reactions of plating Mg on a copper electrode under constant current conditions using the solvents according to Reference Examples 1 and 2;

Referring to FIG. 7, it can be seen that Reference Example 1 takes a low overvoltage at a high layer / discharge rate as compared with Comparative Example 2, ie, a diglyme solvent, during constant current cycling. This is because the solvent of Comparative Example 1, i.e., 1,2-dimethicethane, used as a cosolvent, acted as a low viscosity medium to increase the mobility of dissociated magnesium. Evaluation 4: Initial Overvoltage Characteristics Evaluation

 The electrostatic current cycling of the magnesium secondary batteries according to Reference Examples 1 and 1 was evaluated, and the results are shown in FIG. 8.

 For constant current cycling evaluation, magnesium disc 1T according to Reference Examples 1 and 1 was placed on one side of a coin cell, and a disk type 16pi copper electrode was welded on the other side (magnesium / copper half cell ᅳ 2016 type half cell, welcos After the addition, electrolyte was added and the cell was assembled. Constant current cycling conditions were performed at 0.025C.

 FIG. 8 is a graph showing the results of performing reactions of plating Mg on a copper electrode under constant current conditions of Reference Examples 1 and 1. FIG.

Referring to FIG. 8, the initial overvoltage of Example 1 shows a very low overvoltage of 0.25V while the magnet is initially plated on the copper electrode, whereas the initial overvoltage of Reference Example 1 appears to be relatively high of about 2V. You can check. From this, it can be seen that the magnesium secondary battery according to Example 1 effectively causes plating of the magnet on the surface of the copper electrode. That is, in the magnet metal disk in which the polymer film is introduced according to Example 1, the Grignard derivative included in the polymer film removes the film such as the oxide film existing on the surface of the magnesium metal disk, thereby causing the magnet of the magnesium metal disk to be removed. Can easily dissociate. In addition, the polymer included in the polymer membrane may play a role of supporting the Grignard derivative well. Evaluation 5: Evaluation of Low Oxidation Characteristics of Electrolyte

The evaluation was carried out at a scan rate of 20 mV / S, room temperature conditions for the electrolyte solution prepared in Reference Example 1 and Comparative Example 2, the working electrode is a stainless metal, the reference and the counter electrode is a magnet metal . The results are shown in FIG. ^*

 9 is a graph evaluating the electrochemical acid pollen potential characteristics of the electrolyte according to Reference Example 1 with respect to Comparative Example 2.

 Referring to FIG. 9, it can be seen that the electrochemical oxidative decomposition potential of the electrolyte according to Reference Example 1 was maintained more stably than that of Comparative Example 2.

 In other words, Reference Example 1 has a smaller overvoltage under the same scan rate conditions as compared with Comparative Example 2, which leads to a decrease in the viscosity of the electrolyte due to the introduction of 1,2-dimethicethane and thus the mobility of magnesium ions. Because of the faster the overvoltage is applied to the cell under high charge and discharge conditions. Evaluation 6: Evaluation of Specific Capacity Characteristics of Magnesium Secondary Battery

The magnet secondary battery prepared according to Reference Example 1 was subjected to one cycle at a current of 0.02 C / 0.02 C at room temperature (25 ^° C.), and the results are shown in FIG. 10. At this time, the layer upper limit voltage at normal temperature (25 ^° C) was 2V, the discharge end voltage was 0.5V. 10 is a graph evaluating the specific capacity of the Mo ₆ S ₈ / Mg cell according to Reference Example 1.

Referring to FIG. 10, the electrolyte of Reference Example 1 effectively sterilized magnesium silver at the magnet anode through a very high discharge capacity of 108 mAh / g corresponding to 90% of the theoretical capacity of 120 mAh / g of the Mo ₆ S ₈ anode. It can be seen that the stripping is inserted into the anode. In addition, it can be seen that the electrolyte solution of Reference Example 1 is a stable electrolyte at a high voltage through the potential flat area due to oxidative decomposition of the electrolyte even at a high charging potential of 2V. The present invention is not limited to the above embodiments, but may be manufactured in various forms, and a person of ordinary skill in the art to which the present invention pertains does not change the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims

[Claim 1] An electrolyte comprising a magnesium salt, 1,2-dimethoxyethane, and a glyme-based organic solvent represented by the following formula (1); And magnesium containing a polymer and a Grignard derivative, which is a reaction product of a Lewis base represented by the following formula (2) and a Tuis acid represented by the following formula (3), and a second electrolyte in the form of a layer located on the cathode surface. Electrolyte for secondary batteries: [Formula 1]

[Formula 2], R ³ _a MgCl ₂ - _a [Formula 3] R bAlCl ₃ - _b In Formulas 1 to 3, R ¹ and R ² are each independently a substituted or unsubstituted C2 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a combination thereof, n is an integer from 2 to 5, R ³ and R ⁴ are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a combination thereof, a is an integer from 0 to 2, b is an integer from 0 to 3. 【Claim 2】 In clause 1, The Grignard derivative is an electrolyte for a magnesium secondary battery, which is a compound represented by the following formula 4: [Formula ⁴ ] (R ³ _a MgCl ₂ -a )2-AlCl ₃ In Formula 4 above, R ³ is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a combination thereof, a is an integer from 0 to 3. 【Claim 3】 In clause 1, The Grignard derivative is an electrolyte for a magnesium secondary battery, which is a compound represented by the following formula 5: [Formula 5]

In Formula 5 above, R ⁴ is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a combination thereof, b is an integer from 0 to 3. 【Claim 4】 In clause 1, The electrolyte for a magnesium secondary battery wherein R ¹ and R ² are each independently a substituted or unsubstituted C2 to C20 alkyl group. 【Claim 5】 In clause 1, The glyme-based organic solvent is an electrolyte for a magnesium secondary battery, which is diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or a combination thereof. [Claim 6] In clause 1, The glyme-based organic solvent is an electrolyte for a magnesium secondary battery comprising the 1,2-dimethoxyethane and the solvent represented by Chemical Formula 1 in a volume ratio of 1 to 99:99 to 1. 【Claim 7】 In paragraph 1, The glyme-based organic solvent is an electrolyte for a magnesium secondary battery containing 1,2-dimethoxyethane and diethylene glycol dimethyl ether. [Claim 8] In paragraph 17, The 1,2-dimethoxyethane and the diethylene glycol dimethyl ether are 1 to 90: An electrolyte for a magnesium secondary battery contained in a volume ratio of 90 to 1. 【Claim 9】 In paragraph 1, An electrolyte for a magnesium secondary battery, wherein the glyme-based organic solvent is contained in an amount of 80 to 99% by weight based on the total amount of the electrolyte for the magnesium secondary battery. 【Claim 10】 In paragraph 1, The magnesium salt is magnesium bis (trifluoromethanesulfonyl)imide (magnesium bis(trifluoromethanesulfonyl)limide: Mg(TFSI) ₂ ), magnesium bis(hexafluorophosphate): Mg(PF ₆ ) ₂ ), magnesium bis(perchlorate) (magnesium bis(perchlorate): Mg( C10 ₄ ) ₂ ), magnesium bis(trifluoromethanesulfonyl)imide: Mg(CF ₃ S0 ₃ N) ₂ ), magnesium Bis _{(oxalato)borate (magnesium bis(oxalato)borate (Mg(BOB) 2 ) ,} Magnesium bis (tetrafluoroborate Magnesium containing sulfonyl)imide (magnesium bis(perfluoroethanesulfonyl)imide:Mg(BETI) ₂ ), magnesium trifluoromethanesulfonate (magnesium trifluoromethanesulfonate:Mg(CF3S0 ₃ ) ₂ ), or a combination thereof Electrolyte for secondary batteries. 【Claim 111 In paragraph 1, The electrolyte for a magnesium secondary battery wherein the concentration of the magnesium salt is 0.05 to 1.0M. [Claim 12] In paragraph 1, The polymer and the Grignard derivative are comprised of 10 to 50% by weight of the polymer and 50 to 90% by weight of the Grignard derivative based on the total amount of the second electrolyte. An electrolyte for a magnesium secondary battery. [Claim 13] In clause 1, Electrolyte for a magnesium secondary battery wherein the second electrolyte has a thickness of 1 ffli to 10 ffli. 【Claim 14】 In paragraph 1, The polymer is vinylidene fluoride-hexafluoropropylene copolymer (PVDF-c and HFP, HFP content: 6-15% by weight), polyvinylidene fluoride (PVDF), polyvinylacetate (PVAc), polymethyl meta An electrolyte for magnesium secondary batteries that is crylate (PMMA), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyethylene oxide (PEO), or a combination thereof. [Claim 15] In clause 1, An electrolyte for a magnesium secondary battery wherein the polymer has a weight average molecular weight (Mw) of 100,000 to 600,000. [Claim 16] The electrolyte according to any one of claims 11 to 15; anode; and Ugh · ， A magnesium secondary battery containing.