KR101771330B1 - Electrolyte and secondary battery comprising the same - Google Patents

Abstract

The present invention relates to an electrolyte and a secondary battery comprising the same, wherein the electrolyte comprises a sulfonic solvent represented by the formula (1), an ether solvent represented by the formula (2), and an electrolyte salt represented by the formula (3). The contents of the above Chemical Formulas 1 to 3 are the same as those described in the description of the invention or claims.
The electrolyte may be used in a secondary battery operated by multivalent cations such as Mg ²⁺ or Ca ²⁺ , which is not a monovalent cation such as Li ⁺ ions, to thereby increase the capacity of the secondary battery. It is possible to maximize the characteristics of the magnesium metal cathode or the calcium metal cathode battery by suppressing formation of a film having a very large resistance on the surface of the magnesium metal cathode or calcium metal anode to be used.

Description

ELECTROLYTE AND SECONDARY BATTERY COMPRISING THE SAME BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to an electrolyte and a secondary battery comprising the electrolyte. More particularly, the electrolyte is a secondary battery which is operated by multivalent cations such as Mg ^{2 +} or Ca ^{2 +} , which are not monovalent cations such as Li ⁺ And a secondary battery including the same.

Secondary batteries based on multivalent cations such as Mg ²⁺ , Ca ²⁺ , Al ³⁺ , and Y ³⁺ are required rather than monovalent cations such as Li ⁺ and Na ⁺ ions for high capacity secondary batteries.

However, unlike Li and Na metals, polyvalent metals such as Mg, Ca, Al, and Y are very difficult to be used as negative electrodes for secondary batteries. This is because the electrochemical deposition / dissolution reaction of the metal cathode is inhibited because the film resistance produced on the surface of the polyvalent metal in most organic solvents is much larger than the film resistance on the monovalent metal surface.

In order to solve such a problem, in the prior art documents, Patent Documents 1 and 2 and Non-Patent Document 1 have shown that the characteristics of a magnesium metal cathode can be greatly improved by using a Grignard type electrolyte.

However, since the Grignard electrolyte has a property of deteriorating the cathode material due to high nucleophilicity, the usable cathode material is very limited.

In addition, among the prior art documents, it has been shown that the characteristics of the Al metal cathode can be improved by using an ionic liquid electrolyte in the non-patent reference 2 and a dialkylsulfone based electrolyte in the non-patent reference 3. [

However, the ionic liquid and the sulfone-based electrolyte have a high melting point, and thus have a disadvantage that they exhibit high viscosity at room temperature and low ion conductivity.

1. U.S. Patent No. 6,316,141 2. US Patent No. 6,713,212

1. D. Aurbach et al, Nature, 407, 2000, 724. 2. S.D. Jones et al, J. Electrochem. Soc., 136, 1989,424. 3. L. Legrand, Electrochim Acta, 40, 1995, 1711.

The electrolyte of the present invention can be used in a secondary battery operated by multivalent cations such as Mg ²⁺ or Ca ²⁺ , which is not a monovalent cation such as Li ⁺ ion, so that the capacity of the secondary battery can be increased, It is possible to maximize the characteristics of the magnesium metal cathode or the calcium metal cathode battery by suppressing formation of a film having a very large resistance on the surface of the magnesium metal cathode or the calcium metal anode used in the battery.

The electrolyte according to an embodiment of the present invention includes a sulfonic solvent represented by the following formula (1), an ether solvent represented by the following formula (2), and an electrolyte salt represented by the following formula (3).

[Chemical Formula 1]

R ₁ R ₂ SO ₂

Wherein R ₁ and R ₂ are each independently any one selected from the group consisting of an alkyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an aryl group having 5 to 10 carbon atoms, and R ₁ and R ₂ is an alkyl group, at least one of R ₁ and R ₂ is an alkyl group having 3 to 10 carbon atoms.

(2)

Wherein R ₅ is any one selected from the group consisting of -R ₅₁ - and - (R ₅₁ ) _m -O- (R ₅₂ ) _n -, and R ₅₁ and R ₅₂ are each independently selected from the group consisting of a carbon number M and n are each independently an integer of 0 or 1, and each of R ₆ to R ₉ independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms And an aryl group having 5 to 10 carbon atoms.

(3)

AX ₂

In Formula 3, A is any one selected from the group consisting of Mg and Ca, and X is any one selected from the group consisting of Cl, Br and I.

The sulfone-based solvent may be any one selected from the group consisting of dipropylsulfone, dibutylsulfone, dimethoxysulfone, diethoxysulfone, methoxypropylsulfone, phenylpropylsulfone, and combinations thereof.

The ether-based solvent may be any one selected from the group consisting of dioxolane, dioxane, and combinations thereof.

The electrolyte salt may be a _{MgCl 2, MgBr 2, MgI 2} , CaCl 2, CaBr 2, CaI 2 , and any one selected from the group consisting of.

The electrolyte may contain 30 to 70% by volume of the sulfonic solvent relative to the total volume of the electrolyte.

The electrolyte may contain the ether solvent in an amount of 30 to 70% by volume based on the total volume of the electrolyte.

The electrolyte may include 0.5 to 2M of the electrolytic salt.

The secondary battery according to another embodiment of the present invention includes a cathode including a cathode active material and a cathode including a cathode active material disposed opposite to each other and an electrolyte according to an embodiment of the present invention interposed between the anode and the cathode .

The positive electrode active material is composed of manganese oxide (MnO ₂ ), vanadium oxide (V ₂ O ₅ ), iron oxide, Mo ₆ S ₈ , TiS ₂ , FeSiPO ₄ , FeSiPO ₄ and MF ₂ Lt; / RTI > group.

The negative electrode active material may be any one selected from the group consisting of magnesium, calcium, a carbonaceous material, lithium titanium oxide, an alloy of magnesium and bismuth or tin.

The electrolyte of the present invention can be used in a secondary battery operated by multivalent cations such as Mg ²⁺ or Ca ²⁺ , which is not a monovalent cation such as Li ⁺ ion, so that the capacity of the secondary battery can be increased, It is possible to maximize the characteristics of the magnesium metal cathode or the calcium metal cathode battery by suppressing formation of a film having a very large resistance on the surface of the magnesium metal cathode or the calcium metal anode used in the battery.

1 is an exploded perspective view of a secondary battery according to another embodiment of the present invention.
2 is a cyclic voltammogram (CV) for the electrochemical deposition / desorption reaction of magnesium in the electrolyte prepared in Example 1 of the present invention.
3 is a graph showing a potential change over time of the battery manufactured in Experimental Example 2 of the present invention.
4 is a graph of Coulomb efficiency change according to a cycle of the battery manufactured in Experimental Example 2 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "comprises" or "having" are used to designate the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless otherwise specified herein, the halogen atom means any one selected from the group consisting of fluorine, chlorine, bromine and iodine.

Unless otherwise stated, alkyl groups include primary alkyl groups, secondary alkyl groups, and tertiary alkyl groups.

In the present specification, unless otherwise specified, all the compounds or substituents may be substituted or unsubstituted. The term "substituted" as used herein means that hydrogen is substituted with at least one substituent selected from the group consisting of a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an amino group, a thio group, a methylthio group, an alkoxy group, a nitryl group, an aldehyde group, Substituted with any one selected from the group consisting of acetal, ketone, alkyl, perfluoroalkyl, cycloalkyl, heterocycloalkyl, allyl, benzyl, aryl, heteroaryl, .

Unless otherwise specified in the present specification, the alkyl group is a linear or branched alkyl group of 1 to 10 carbon atoms, an allyl group of 2 to 10 carbon atoms, an alkoxy group of 1 to 10 carbon atoms, a perfluoroalkyl group of 1 to 10 carbon atoms The perfluoroalkoxy group is a perfluoroalkoxy group having 1 to 10 carbon atoms, the cycloalkyl group is a cycloalkyl group having 3 to 32 carbon atoms, the heterocycloalkyl group is a heterocycloalkyl group having 2 to 32 carbon atoms, the aryl group has a carbon number of 6 An aryl group or a heteroaryl group having 2 to 30 carbon atoms means a heteroaryl group having 2 to 30 carbon atoms.

Unless otherwise specified herein, an aryl group means a monocyclic or polycyclic compound having 6 to 30 carbon atoms and derivatives thereof containing at least one benzene ring, for example, a benzene ring, toluene having an alkyl side chain attached to a benzene ring Or biphenyl in which two or more benzene rings are bonded in a single bond, such as xylene, and naphthalene condensed with two or more benzene rings such as fluorene, xanthone, or anthraquinone condensed with a cycloalkyl group or a heterocycloalkyl group, Or anthracene.

The secondary battery according to an embodiment of the present invention includes a case, an electrode assembly disposed inside the case, including an anode and a cathode, and a separator interposed between the anode and the cathode, and an electrolyte injected into the case .

1 is an exploded perspective view of a secondary battery 1 according to another embodiment of the present invention. 1, the secondary battery 1 includes a separator 7 disposed between a cathode 3, an anode 5, the cathode 3, and an anode 5 to manufacture an electrode assembly 9 And then placing it in the case 15 and injecting an electrolyte (not shown) so that the negative electrode 3, the positive electrode 5 and the separator 7 are impregnated into the electrolyte.

The electrolyte includes a sulfonic solvent, an ether solvent, and an electrolytic salt.

The sulfone-based solvent may be represented by the following formula (1).

[Chemical Formula 1]

R ₁ R ₂ SO ₂

In Formula 1, R ₁ and R ₂ are each independently any one selected from the group consisting of an alkyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an aryl group having 5 to 10 carbon atoms. The alkyl group may be an ethyl group, a propyl group, a butyl group or the like, and the alkoxy group may be a methoxy group, an ethoxy group or the like, and the aryl group may be a phenyl group or the like.

When both R ₁ and R ₂ are alkyl groups, at least one of R ₁ and R ₂ may be an alkyl group having 3 to 10 carbon atoms. For example, R ₁ and R ₂ may both be a propyl group, or both may be a butyl group, and when R ₁ is an ethyl group, R ₂ may be a propyl group or a butyl group.

Specifically, the sulfone solvent may be any one selected from the group consisting of dipropylsulfone, dibutylsulfone, dimethoxysulfone, diethoxysulfone, methoxypropylsulfone, phenylpropylsulfone, and combinations thereof.

The electrolyte may contain 30 to 70% by volume, preferably 45 to 55% by volume, of the sulfone-based solvent with respect to the total volume of the electrolyte. When the content of the sulfonic solvent is less than 30 vol%, the solubility of the solvent is lowered and the electrolytic salt is not dissolved, so that the ion conductivity of the electrolyte can be reduced. When the content exceeds 70 vol%, the viscosity of the electrolyte increases, And the electrolyte may solidify.

The ether-based solvent may be represented by the following formula (2).

(2)

In Formula 2, R ₅ is - (R ₅₁ ) _m -O- (R ₅₂ ) _n -. Each of R ₅₁ and R ₅₂ independently represents an alkylene group having 1 to 3 carbon atoms, and each of m and n is independently an integer of 0 or 1. That is, R ₅ may be -CH ₂ -O-, -O-CH ₂ -, -CH ₂ -O-CH ₂ -, and the like.

Each of R ₆ to R ₉ is independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an aryl group having 5 to 10 carbon atoms.

Specifically, the ether solvent may be any one selected from the group consisting of dioxolane, dioxane, and combinations thereof. When the ether-based solvent contains two or more hetero-oxygen atoms in the ring structure such as dioxolane or dioxane, the boiling point of the solvent is higher than that in the case where one hetero-oxygen atom is contained in the ring structure such as tetrahydrofuran, It is possible to reduce the volatilization and thus the risk of increasing the electrolyte concentration and increasing the vapor pressure inside the cell. For reference, the boiling point of the tetrahydrofuran is 66 캜, the dioxolane is 75 캜, and the dioxane is 101 캜.

The electrolyte may contain the ether solvent in an amount of 30 to 70% by volume, preferably 45 to 55% by volume, based on the total volume of the electrolyte. When the content of the ether solvent is less than 30% by volume, the viscosity of the electrolyte is increased to increase the internal resistance of the electrolyte and the electrolyte can be coagulated. When the content of the ether solvent exceeds 70% by volume, the solubility of the solvent is lowered, Can be reduced.

Meanwhile, the electrolyte may contain the sulfone-based solvent and the ether-based solvent in a volume ratio of 1: 3 to 3: 1, preferably 1: 2 to 2: 1. When the electrolyte contains less than 3: 1 by volume of the ether-based solvent, the viscosity of the electrolyte is increased to increase the internal resistance in the electrolyte and the electrolyte to solidify, and the ether- The solubility of the solvent is lowered so that the electrolytic salt is not dissolved and the ion conductivity of the electrolyte may be reduced.

The electrolytic salt may be represented by the following formula (3).

(3)

AX ₂

In Formula 3, A is any one selected from the group consisting of Mg and Ca, and X is any one selected from the group consisting of Cl, Br and I.

Specifically, the electrolytic salt may be any one selected from the group consisting of MgCl ₂ , MgBr ₂ , MgI ₂ , CaCl ₂ , CaBr ₂ , CaI _2, and combinations thereof.

The electrolyte may contain 0.5 to 2 M of the electrolytic salt, and preferably 0.7 to 1.5 M. If the content of the electrolytic salt is less than 0.5M, the ionic conductivity of the electrolyte may be low and the electrolyte may not sufficiently serve as an electrolyte. If the content exceeds 2M, the electrolytic salt does not dissolve in a supersaturated state and the viscosity of the electrolyte increases. This can be a problem.

The electrolyte may be used in a secondary battery operated by multivalent cations such as Mg ²⁺ or Ca ²⁺ , which is not a monovalent cation such as Li ⁺ ions, to thereby increase the capacity of the secondary battery. It is possible to maximize the characteristics of the magnesium metal cathode or the calcium metal cathode battery by suppressing formation of a film having a very large resistance on the surface of the magnesium metal cathode or the calcium metal anode used for the cathode.

That is, the inventors of the present invention have found that when the sulfone-based solvent and the ether-based solvent are used together, the characteristics of the magnesium metal cathode or the calcium metal anode can be maximized, and the magnesium anode characteristic is that the cation of the electrolytic salt is magnesium Or calcium, it is found that the anion is most influenced by the type of anion, and especially when the anion has a halogen anion such as Cl ^- , Br ^- or I ^- .

The negative electrode 3 may be prepared by preparing a composition for forming a negative electrode active material layer by mixing a negative electrode active material, a binder and an optional conductive agent, and then applying the composition to a negative electrode current collector such as a copper foil.

As the negative electrode active material, magnesium, calcium metal, magnesium or calcium ions can be used for all materials which cause de-insertion or alloy / non-alloy reaction.

Specifically, the negative electrode active material may be a magnesium metal or a calcium metal, and may be a carbonaceous material such as artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, or the like capable of intercalating magnesium or calcium ions or lithium titanium oxide Can be used. As the negative electrode active material, an alloy of magnesium and bismuth or tin causing an alloy / non-alloy reaction with a magnesium metal or a calcium metal may be used.

Examples of the lithium titanium oxide include, but are not limited to, Li _0.8 Ti _2.2 O ₄ , Li _2.67 Ti _1.33 O ₄ , LiTi ₂ O ₄ , Li _1.33 Ti _1.67 O ₄ , and Li _1.14 Ti _1.71 O ₄ . It is not.

The binder serves to attach the electrode active material particles to each other and to adhere the electrode active material to the current collector. Specific examples of the binder include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC) , Starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber , Fluorine rubber, various copolymers thereof, and the like.

In addition, preferred examples of the solvent include dimethyl sulfoxide (DMSO), alcohol, N-methylpyrrolidone (NMP), acetone or water.

The current collector may be any metal selected from the group consisting of copper, aluminum, stainless steel, titanium, silver, palladium, nickel, alloys thereof, and combinations thereof. The stainless steel may be carbon, nickel, The aluminum alloy may be an aluminum-cadmium alloy. Alternatively, a non-conductive polymer surface-treated with a conductive material, a conductive polymer, or the like may be used.

The conductive material is used for imparting conductivity to the electrode. Any conductive material can be used without causing any chemical change in the battery. Examples of the conductive material include natural graphite, artificial graphite, carbon black, acetylene black, Metal powders such as black, carbon fiber, copper, nickel, aluminum, and silver, metal fibers, and the like, and conductive materials such as polyphenylene derivatives may be used alone or in combination.

The method of applying the current collector composition for forming the anode active material layer may be selected from known methods in consideration of the characteristics of materials and the like or may be carried out by a new suitable method. For example, it is preferable that the composition for forming the anode active material layer is dispersed on a current collector and then uniformly dispersed using a doctor blade or the like. In some cases, a method of performing the distribution and dispersion processes in a single process may be used. In addition, methods such as die casting, comma coating, and screen printing may be used.

The positive electrode 5 is prepared by mixing a positive electrode active material, a conductive agent and a binder in the same manner as the negative electrode 3 to prepare a composition for forming a positive electrode active material layer. The composition for forming the positive electrode active material layer is then applied to a positive electrode current collector Followed by rolling.

As the cathode active material, it is possible to use any material that causes de-insertion or conversion of magnesium or calcium ions.

Specifically, examples of the cathode active material include oxide-based compounds such as manganese oxide (MnO ₂ ), vanadium oxide (V ₂ O ₅ ) or iron oxide, sulfide-based compounds such as Mo ₆ S ₈ or TiS ₂ , FeSiPO ₄ or FeSiPO ₄ And the like, a compound of the conversion type such as MF ₂ (wherein M is Fe or Cu) can be used.

As the separator 7, a conventional porous polymer film conventionally used as a separator, such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer The porous polymer film made of a polyolefin-based polymer may be used alone or in a laminate thereof, or a nonwoven fabric made of a conventional porous nonwoven fabric, for example, a glass fiber of high melting point, polyethylene terephthalate fiber or the like may be used. It is not.

Conductive lead members 10 and 13 for collecting a current generated during a battery operation can be attached to the cathode 3 and the anode 5 respectively and the lead members 10 and 13 are respectively connected to the anode 5, And the current generated in the cathode (3) can be led to the positive electrode terminal and the negative electrode terminal.

The secondary battery 1 can be manufactured by a conventional method, and a detailed description thereof will be omitted herein. The present invention is not limited to the cylindrical secondary battery 1, but the present invention is not limited to the cylindrical secondary battery 1, and any shape such as a square, a coin, or a pouch can be used as long as it can operate as a battery. May also be possible.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

[Experimental Example 1: Evaluation of charging / discharging efficiency of magnesium metal cathode]

First, a pyrolytic graphite electrode (PGE) was used as the working electrode used for the positive electrode collector of the lithium secondary battery, a magnesium metal was used as the reference electrode and the auxiliary electrode, and the following Examples 1 to 6 and Comparative Examples 1 to 6 were used. The electrochemical deposition / dissolution reaction of magnesium was evaluated using the electrolyte prepared in Example 9.

At this time, the electrochemical deposition / desorption characteristics of magnesium were measured at a scanning rate of 20 mV / s under a glove box of an argon (Ar) atmosphere having a moisture and oxygen concentration of 10 ppm or less at a temperature of 30 ° C., voltammetry, CV). The Coulombic efficiency of the electrochemical deposition / desorption reaction of magnesium is shown in Table 1 below.

(Example 1)

(DPSO ₂ / dioxolane = 1/1 (volume ratio), 0.8M MgCl ₂ ) was used as the electrolyte solution, using dipropylsulfone (DPSO ₂ ) as a sulfonic solvent, dioxolane as an ether solvent and MgCl ₂ as an electrolytic salt. .

(Example 2)

An electrolyte was prepared in the same manner as in Example 1 except that dibutylsulfone (DBSO ₂ ) was used as a sulfonic solvent.

(Example 3)

An electrolyte was prepared in the same manner as in Example 1 except that MgI ₂ was used as the electrolytic salt.

(Example 4)

An electrolyte was prepared in the same manner as in Example 1 except that the volume ratio of DPSO ₂ and dioxolane was changed to 1/2.

(Example 5)

An electrolyte was prepared in the same manner as in Example 1 except that the volume ratio of DPSO ₂ and dioxolane was changed to 2/1.

(Comparative Example 1)

An electrolyte was prepared in the same manner as in Example 1 except that dimethylsulfone (DMSO ₂ ) was used as a sulfone-based solvent.

(Comparative Example 2)

An electrolyte was prepared in the same manner as in Example 1, except that ethyl methyl sulfone (EMSO ₂ ) was used as the sulfone type solvent.

(Comparative Example 3)

An electrolyte was prepared in the same manner as in Example 1 except that ethyl methyl sulfone (EMSO ₂ ) was used as the sulfone type solvent and an ether type solvent was not used.

(Comparative Example 4)

An electrolyte was prepared in the same manner as in Example 1 except that the ether solvent was not used and the content of the electrolytic salt was changed to 1.0M.

(Comparative Example 5)

An electrolyte was prepared in the same manner as in Example 2 except that the ether solvent was not used and the electrolytic salt content was changed to 1.0M.

(Comparative Example 6)

An electrolyte was prepared in the same manner as in Example 1 except that a sulfonic solvent was not used.

(Comparative Example 7)

An electrolyte was prepared in the same manner as in Example 1 except that? -Butyrolactone (GBL) was used instead of the ether-based solvent.

(Comparative Example 8)

An electrolyte was prepared in the same manner as in Example 1 except that acetonitrile was used instead of the ether-based solvent.

(Comparative Example 9)

An electrolyte was prepared in the same manner as in Example 1 except that propylene carbonate (PC) was used instead of the ether-based solvent.

(Comparative Example 10)

An electrolyte was prepared in the same manner as in Example 1 except that butyl methyl ether (BME) was used instead of the ether-based solvent.

(Comparative Example 11)

An electrolyte was prepared in the same manner as in Example 1 except that butyl ethyl ether (BEE) was used in place of the ether-based solvent.

(Comparative Example 12)

An electrolyte was prepared in the same manner as in Example 1 except that Mg (ClO ₄ ) ₂ was used as an electrolysis salt.

(Comparative Example 13)

An electrolyte was prepared in the same manner as in Example 1 except that Mg (TFSI) ₂ was used as an electrolytic salt.

(Comparative Example 14)

An electrolyte was prepared in the same manner as in Example 1 except that tetrahydrofuran was used instead of the ether-based solvent.

Sulfonic solvent
(Volume ratio) Ether solvent
(Volume ratio) Sea salt
(Molar concentration) Coulomb efficiency (%) Example 1 DPSO ₂ (1) Dioxolane (1) MgCl ₂ (0.8 M) 85 Example 2 DBSO ₂ (1) Dioxolane (1) MgCl ₂ (0.8 M) 84 Example 3 DPSO ₂ (1) Dioxolane (1) MgI ₂ (0.8 M) 65 Example 4 DPSO ₂ (1) Dioxolane (2) MgCl ₂ (0.8 M) 80 Example 5 DPSO ₂ (2) Dioxolane (1) MgCl ₂ (0.8 M) 71 Comparative Example 1 DMSO ₂ (1) Dioxolane (1) MgCl ₂ (0.8 M) No reaction, no MgCl ₂ Comparative Example 2 EMSO ₂ (1) Dioxolane (1) MgCl ₂ (0.8 M) 44 Comparative Example 3 EMSO ₂ (1) - MgCl ₂ (1.0M) 24 (65 DEG C) Comparative Example 4 DPSO ₂ (1) - MgCl ₂ (1.0M) 33 (35 DEG C) Comparative Example 5 DBSO ₂ (1) - MgCl ₂ (1.0M) No reaction, no MgCl ₂ Comparative Example 6 - Dioxolane (1) MgCl ₂ (0.8 M) no response Comparative Example 7 DPSO ₂ (1) GBL (1) MgCl ₂ (0.8 M) no response Comparative Example 8 DPSO ₂ (1) Acetonitrile (1) MgCl ₂ (0.8 M) no response Comparative Example 9 DPSO ₂ (1) PC (1) MgCl ₂ (0.8 M) no response Comparative Example 10 DPSO ₂ (1) BME (1) MgCl ₂ (0.8 M) no response Comparative Example 11 DPSO ₂ (1) BEE (1) MgCl ₂ (0.8 M) no response Comparative Example 12 DPSO ₂ (1) Dioxolane (1) _{Mg (ClO 4) 2 (0.8M} ) no response Comparative Example 13 DPSO ₂ (1) Dioxolane (1) Mg (TFSI) ₂ (0.8M) no response Comparative Example 14 DPSO ₂ (1) Tetrahydrofuran (1) MgCl ₂ (0.8 M) 58

The cyclic voltammogram (CV) for the electrochemical deposition / desorption reaction of magnesium in the electrolyte prepared in Example 1 is shown in FIG. As shown in FIG. 2, it can be seen that the electrochemical deposition reaction of Mg ions to Mg metal on the PGE is reversed at a voltage of -0.5 V (vs.

Further, as shown in Table 1, it can be seen that the coulombic efficiency of the electrochemical deposition / desorption reaction of Mg in the electrolyte prepared in Example 1 is as excellent as 85%. Also, as can be seen from FIG. 2, it can be seen that the oxidative decomposition reaction of the electrolyte does not occur up to 2.5 V (vs. Mg).

Thus, the electrolyte of Example 1 exhibits reversible Mg electrochemical deposition / desorption reaction and excellent oxidation resistance.

On the other hand, high coulombic efficiency was also observed in the electrolyte of Example 2 using DBSO ₂ as the sulfonic solvent and the electrolyte of Example 3 using MgI ₂ as the electrolytic salt.

Also, Example 4 and Example 5 in which the volume ratio of DPSO ₂ / dioxolane was 1/2 and 2/1 respectively showed high Coulomb efficiency.

On the other hand, in Comparative Example 1 and Comparative Example 2 in which only the alkyl group having 2 or less carbon atoms such as DMSO ₂ and EMSO _{2 was used} as the sulfone-based solvent, electrochemical deposition / desorption reaction of Mg was not observed at all or low Coulomb efficiency was shown.

In addition, the electrochemical characteristics of Mg are relatively poor in Comparative Examples 3 to 5 using only a sulfonic solvent alone and Comparative Example 6 using only an ether solvent alone. This proves that the combination of a sulfonic solvent and an etheric solvent shows excellent properties.

Also, electrochemical deposition / desorption reaction of Mg was hardly observed in Comparative Examples 7 to 11 where GBL, Acetonitrile, PC, BME and BEE were used in place of an ether solvent. This supports that the ether-based solvent having the structure of the formula (2) shows superior properties to other solvents.

In Comparative Example 12 and Comparative Example 13 in which Mg (ClO ₄ ) or Mg (TFSI) ₂ was used as the electrolytic salt, the efficiency was lower than that of Example 1 in which MgCl ₂ was used or Example 3 in which MgI ₂ was used see. This proves that excellent properties are realized when the electrolytic salt of formula (3) is used.

[Experimental Example 2: Evaluation of life characteristics of magnesium secondary battery]

In order to evaluate the battery characteristics of the electrolyte for a magnesium secondary battery derived from the present invention, the following magnesium secondary battery was constructed. Mo ₆ S ₈ cathode active material, PVDF binder, and carbon conductive material were used as an anode at a ratio of 80:10:10. A coin-type battery was fabricated using the positive electrode, the magnesium metal negative electrode, the PE separator, and the electrolyte of Example 1 (0.8M MgCl ₂ DPSO ₂ / dioxolane (1/1, V / V)).

The prepared battery was charged and discharged at a constant current of 0.2 mA at 0.3 to 1.8 V at room temperature. A graph of potential change with time was shown in FIG. 3, and a graph of Coulomb efficiency change according to a cycle is shown in FIG. Respectively.

FIG. 3 shows that the Mg / Mo ₆ S ₈ battery exhibits a highly reversible Mg decontamination reaction. Further, as shown in FIG. 4, the battery maintains a coulombic efficiency close to 100% up to 25 times or more, which demonstrates the excellent reversible charge-discharge characteristics of the battery. On the other hand, when the above-described batteries were manufactured using the electrolytes of Comparative Examples 1 to 13, the batteries did not operate properly under the charge / discharge conditions.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

1: secondary battery
3: cathode
5: anode
7: Separator
9: Electrode assembly
10, 13: lead member
15: Case

Claims (10)

A sulfone-based solvent represented by the following formula (1)
An ether solvent represented by the following formula (2), and
And an electrolytic salt represented by the following formula (3)
An electrolyte comprising the sulfone-based solvent and the ether-based solvent in a volume ratio of 1: 3 to 3: 1.
[Chemical Formula 1]
R ₁ R ₂ SO ₂
(In the formula 1, wherein R ₁ and R ₂ are either each independently having from 2 to 10 carbon atoms an alkyl group, an alkoxy group having 1 to 10 carbon atoms group and selected from the group consisting of carbon number 5-10 aryl group, and wherein R ₁ And R < _{2 >} are all alkyl groups, at least either of R < ₁ > and R < ₂ &
(2)

Wherein R ₅ is - (R ₅₁ ) _m -O- (R ₅₂ ) _n -, R ₅₁ and R ₅₂ are each independently an alkylene group having 1 to 3 carbon atoms, m and n Are each independently an integer of 0 or 1,
Each of R ₆ to R ₉ is independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an aryl group having 5 to 10 carbon atoms)
(3)
AX ₂
(Wherein A is any one selected from the group consisting of Mg and Ca, and X is any one selected from the group consisting of Cl, Br and I) The method according to claim 1,
Wherein the sulfone-based solvent is any one selected from the group consisting of dipropylsulfone, dibutylsulfone, dimethoxysulfone, diethoxysulfone, methoxypropylsulfone, phenylpropylsulfone, and combinations thereof. The method according to claim 1,
Wherein the ether-based solvent is any one selected from the group consisting of dioxolane, dioxane, and combinations thereof. The method of claim 1,
The electrolyte salt is _{MgCl 2, MgBr 2, MgI 2} , CaCl 2, CaBr 2, CaI 2 and any one of the electrolyte will be selected from the group consisting of a combination thereof. The method according to claim 1,
Wherein the electrolyte comprises 30 to 70% by volume of the sulfone-based solvent with respect to the total volume of the electrolyte. The method according to claim 1,
Wherein the electrolyte contains 30 to 70% by volume of the ether-based solvent with respect to the total volume of the electrolyte. The method according to claim 1,
Wherein the electrolyte comprises 0.5 to 2 M of the electrolytic salt. A negative electrode including a positive electrode active material and a negative electrode active material disposed opposite to each other, and
And an electrolyte interposed between the anode and the cathode,
Wherein the electrolyte is the electrolyte according to claim 1. 9. The method of claim 8,
The positive electrode active material is composed of manganese oxide (MnO ₂ ), vanadium oxide (V ₂ O ₅ ), iron oxide, Mo ₆ S ₈ , TiS ₂ , FeSiPO ₄ , FeSiPO ₄ and MF ₂ Lt; RTI ID = 0.0 > 1, < / RTI > 9. The method of claim 8,
Wherein the negative electrode active material is any one selected from the group consisting of magnesium, calcium, a carbonaceous material, lithium titanium oxide, an alloy of magnesium and bismuth or tin.

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