Electrolyte for magnesium battery and magnesium battery

Abstract

The electrolyte solution for a magnesium battery contains a solvent, an electrolyte salt, and an additive. The electrolyte salt contains a magnesium salt represented by formula (1). The additive contains at least one of a first magnesium compound represented by formula (2), a second magnesium compound represented by formula (3), and a polycyclic aromatic hydrocarbon. Mg [B (OC (R1) 3) 4] 2 (1) (24 R1 are each any one of hydrogen (H), fluorine (F), alkyl group, and fluorinated alkyl group, provided that at least one of the 24 R1 is any one of fluorine and fluorinated alkyl group) Mg [N (Si (R2) 3) 2] 2... (2) (12 R2 are each hydrogen or alkyl group) Mg (R3) 2... (3) (wherein two R3 are each hydrogen and / or boron hydride (BH4))

Description

Technical Field

[0001] The present technology relates to an electrolyte for a magnesium battery and a magnesium battery. Background Art

[0002] The development of magnesium batteries is underway. The magnesium batteries include a positive electrode, a negative electrode, and an electrolyte solution (electrolyte solution for magnesium batteries) containing a magnesium salt as an electrolyte salt.

[0003] As technologies related to the structure of magnesium batteries, some technologies are known. Specifically, it is proposed to synthesize magnesium salt (Mg[B(OCH(CF3)2)4]2) using magnesium compound (Mg(BH4)2) as a raw material (for example, refer to non-patent document 1), and an electrolyte solution using the magnesium salt (for example, refer to non-patent document 2). In addition, it is proposed to contain a specific anion (B(OCH(CF3)2)4 - ) and magnesium chloride (MgCl2) electrolyte (for example, refer to Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 08-171916

[0007] Non-patent literature

[0008] Non-patent document 1: A new class of non-corrosive, highly efficient electrolytes for rechargeable magnesium batteries, J. Mater. Chem. A 2017, 5, 10815-10820

[0009] Non-patent document 2: Critical Issues of Fluorinated Alkoxyborate-BasedElectrolytes in Magnesium Battery Applications, ACS Appl. Mater. Interfaces2020, 12, 39135-39144 Summary of the invention

[0010] Various studies have been conducted on the structure of magnesium batteries. However, since the electrochemical activity of the electrolyte used in the magnesium batteries is still insufficient, there is room for improvement.

[0011] There is a need for an electrolyte for a magnesium battery and a magnesium battery that can achieve excellent electrochemical activity.

[0012] An electrolyte for a magnesium battery according to an embodiment of the present technology includes a solvent, an electrolyte salt, and an additive. The electrolyte salt includes a magnesium salt represented by formula (1). The additive includes at least one of a first magnesium compound represented by formula (2), a second magnesium compound represented by formula (3), and a polycyclic aromatic hydrocarbon.

[0013] Mg[B(OC(R1)3)4]2…(1)

[0014] (The 24 R1s are each any one of hydrogen (H), fluorine (F), an alkyl group, and a fluorinated alkyl group. At least one of the 24 R1s is any one of fluorine and a fluorinated alkyl group.)

[0015] Mg[N(Si(R2)3)2)]2…(2)

[0016] (Each of the 12 R2s is either hydrogen or an alkyl group.)

[0017] Mg(R3)2…(3)

[0018] (The two R3 are either hydrogen or boron hydride (BH4).

[0019] A magnesium battery according to an embodiment of the present technology includes a positive electrode, a negative electrode, and an electrolyte for a magnesium battery. The electrolyte for a magnesium battery has the same configuration as that of the electrolyte for a magnesium battery according to the embodiment of the present technology described above.

[0020] According to an electrolyte for a magnesium battery or a magnesium battery according to one embodiment of the present technology, since the electrolyte for a magnesium battery contains an electrolyte salt and an additive, the electrolyte salt contains the above-mentioned magnesium salt, and the additive contains at least one of the above-mentioned first magnesium compound, the second magnesium compound and the polycyclic aromatic hydrocarbon, excellent electrochemical activity can be obtained.

[0021] It should be noted that the effects of the present technology are not limited to the effects described here, and may be any of a series of effects related to the present technology described later. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is an example of the analysis result (cyclic voltammogram) of the electrolyte solution using the cyclic voltammetry method.

[0023] Figure 2 This is a cross-sectional view schematically showing the structure of a magnesium battery in one embodiment of the present technology. DETAILED DESCRIPTION

[0024] Below, while referring to the attached Figure 1One embodiment of the present technology will be described in detail. It should be noted that the order of description is as follows.

[0025] 1. Electrolyte for magnesium batteries

[0026] 1-1. Composition

[0027] 1-2. Manufacturing method

[0028] 1-3. Function and effect

[0029] 1-4. Electrochemical activity of electrolyte for magnesium batteries

[0030] 2. Magnesium battery

[0031] 2-1. Structure

[0032] 2-2. Action

[0033] 2-3. Function and effect

[0034] 3. Uses of magnesium batteries

[0035] <1. Electrolyte for magnesium batteries>

[0036] First, an electrolyte solution for a magnesium battery (hereinafter simply referred to as “electrolyte solution”) in one embodiment of the present technology will be described.

[0037] The electrolyte described here is a liquid electrolyte used in magnesium batteries. In addition, the use of the electrolyte is not limited to magnesium batteries, so the electrolyte can also be used for other purposes besides magnesium batteries.

[0038] <1-1. Structure>

[0039] The electrolyte solution contains a solvent, an electrolyte salt, and an additive.

[0040] [Solvent]

[0041] The solvent is a material that dissolves or disperses the electrolyte salt, and is any one or two or more of organic solvents.

[0042] The type of the solvent is not particularly limited, but the solvent preferably contains an ether compound because the electrolyte salt is sufficiently dissolved or dispersed.

[0043] The ether compound is a general term for compounds having an ether bond (-O-), and may be a chain compound or a cyclic compound. Specific examples of ether compounds are dimethoxyethane, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and tetrahydrofuran. This is because the electrolyte salt is stably dissolved or dispersed. The specific examples of a series of ether compounds described here are mainly so-called glyme ethers.

[0044] [Electrolyte salt]

[0045] The electrolyte salt is a substance that is ionized in a solvent, and includes a magnesium salt. Specifically, the magnesium salt includes any one or two or more of the compounds represented by formula (1).

[0046] Mg[B(OC(R1)3)4]2…(1)

[0047] (The 24 R1s are each any one of hydrogen (H), fluorine (F), an alkyl group, and a fluorinated alkyl group. At least one of the 24 R1s is any one of fluorine and a fluorinated alkyl group.)

[0048] From formula (1), it can be seen that the magnesium salt contains magnesium ions (Mg 2＋ ) as cations and contains two boron-containing ions ([B(OC(R1)3)4 - ]) as the anion.

[0049] As described above, the 24 R1s can be any one of hydrogen, fluorine, alkyl and fluorinated alkyl, without any particular limitation. Among them, one or more of the 24 R1s are any one of fluorine and fluorinated alkyl. Therefore, the compound in which all 24 R1s are any one of hydrogen and alkyl does not belong to the magnesium salt described here.

[0050] The number of carbon atoms in the alkyl group is not particularly limited. In addition, the type of the alkyl group may be linear or branched. Specific examples of the alkyl group are methyl and ethyl. Among them, the alkyl group is preferably methyl. This is because the solubility of the magnesium salt is improved.

[0051] The fluorinated alkyl group is a group in which one or two or more hydrogen atoms in the alkyl group are replaced by fluorine atoms. The number of carbon atoms in the fluorinated alkyl group is not particularly limited, and the number of fluorine atoms in the fluorinated alkyl group is not particularly limited.

[0052] Specific examples of magnesium salts include Mg[B(OCH(CF3)2)4]2, Mg[B(OC(CF3)3)4]2, Mg[B(OCH(CF3)(CH3))4]2, Mg[B(OC(CF3)2(CH3))4]2, Mg[B(OC(CF3)(CH3)2)4]2, Mg[B(OC(CF3)(CH3)2)4]2, Mg[B(OCF(CH3)2)4]2, and Mg[B(OCF(CF3)2)4]2.

[0053] The content (mol / kg) of the electrolyte salt in the electrolytic solution is not particularly limited and can be arbitrarily set. The content of the electrolyte salt described here is the content of the electrolyte salt relative to the solvent.

[0054] [additive]

[0055] The additive includes any one or two or more of a first magnesium compound, a second magnesium compound, and polycyclic aromatic hydrocarbons.

[0056] The electrolyte solution contains the additive because, compared with the case where the electrolyte solution does not contain the additive and the case where the electrolyte solution contains other additives, the electrochemical activity is greatly improved even if the electrolyte solution contains the electrolyte salt (magnesium salt).

[0057] Specifically, if the electrolyte solution does not contain an additive, sufficient electrochemical activity cannot be obtained, and sometimes no electrochemical activity can be obtained at all.

[0058] In addition, if the electrolyte contains a magnesium salt and other additives, the electrochemical activity is slightly improved compared to the case where the electrolyte does not contain the additives, but the electrochemical activity is not sufficiently improved. The other additives are compounds having a structure similar to that of the additives (the first magnesium compound and the second magnesium compound), specifically, magnesium chloride (MgCl2) and the like.

[0059] In contrast, if the electrolyte contains a magnesium salt and an additive, the structure of the magnesium complex formed from the magnesium salt changes appropriately, and the surface of the magnesium metal is activated, thereby improving the ion conductivity of the electrolyte and obtaining excellent electrochemical activity.

[0060] The content (weight %) of the additive in the electrolyte solution is not particularly limited and can be set arbitrarily. When the electrolyte solution contains two or more additives, the content of the additive described here is the total content of each of the two or more additives.

[0061] (First magnesium compound)

[0062] The first magnesium compound contains any one or two or more of the compounds represented by formula (2).

[0063] Mg[N(Si(R2)3)2)]2…(2)

[0064] (Each of the 12 R2s is either hydrogen or an alkyl group.)

[0065] As can be seen from formula (2), the first magnesium compound is a compound in which two bis(trimethylsilyl)amine-type groups (—N(SiR 23 ) 2 ) are bonded to the magnesium atom.

[0066] As described above, the 12 R2 groups can be any one of hydrogen and alkyl groups without any particular limitation. The number of carbon atoms in the alkyl group is not particularly limited, and the alkyl group may be linear or branched. Specific examples of the alkyl group include methyl and ethyl groups.

[0067] Specific examples of the first magnesium compound are Mg[(CH3)3Si-N-Si(CH3)3]2 and the like.

[0068] (Second magnesium compound)

[0069] The second magnesium compound contains any one or two or more of the compounds represented by formula (3).

[0070] Mg(R3)2…(3)

[0071] (The two R3 are either hydrogen or boron hydride (BH4).

[0072] As can be seen from formula (3), the second magnesium compound is a compound in which two hydrogen-containing groups (R3) are bonded to the magnesium atom. As described above, the two R3 groups are not particularly limited as long as they are either hydrogen or borohydride.

[0073] Specific examples of the second magnesium compound are MgH2 and Mg(BH4)2.

[0074] (Polycyclic Aromatic Hydrocarbons)

[0075] Polycyclic aromatic hydrocarbons are a general term for hydrocarbons in which two or more aromatic rings (benzene rings) not including heteroatoms and substituents are condensed. The type of polycyclic aromatic hydrocarbons may be only one or two or more.

[0076] In the polycyclic aromatic hydrocarbon, the number of aromatic rings and the condensation state of two or more aromatic rings are not particularly limited. That is, the number of aromatic rings is not particularly limited as long as it is two or more. In addition, the two or more aromatic rings can be condensed in a linear or non-linear manner.

[0077] Specific examples of polycyclic aromatic hydrocarbons formed by linear condensation of two or more aromatic rings include naphthalene, anthracene, tetracene, pentacene, hexacene, heptacene, etc. Specific examples of polycyclic aromatic hydrocarbons formed by non-linear condensation of two or more aromatic rings include phenanthrene, chrysene, pyrene, triphenylene, benzopyrene, coronene, coronene, and cobaren, etc.

[0078] Among them, the polycyclic aromatic hydrocarbons preferably include acene. This is because the electrochemical activity of the electrolyte is sufficiently improved. Specific examples of acene are the above-mentioned naphthalene, anthracene, tetracene, pentacene, hexacene, and heptacene.

[0079] <1-2. Manufacturing method>

[0080] In the case of manufacturing an electrolyte, an electrolyte salt containing a magnesium salt is put into a solvent, and then an additive is put into the solvent. In this case, as an additive, any one or more of a first magnesium compound, a second magnesium compound, and a polycyclic aromatic hydrocarbon is used. Thus, the electrolyte salt and the additive are respectively dissolved or dispersed in the solvent, thereby preparing an electrolyte.

[0081] <1-3. Functions and effects>

[0082] According to the electrolyte solution, the electrolyte solution includes an electrolyte salt and an additive, the electrolyte salt includes the above-mentioned magnesium salt, and the additive includes any one or two or more of the above-mentioned first magnesium compound, second magnesium compound and polycyclic aromatic hydrocarbon.

[0083] In this case, as described above, the structure of the magnesium complex formed from the magnesium salt is appropriately changed compared to the case where the electrolyte does not contain an additive and the case where the electrolyte contains other additives, and the surface of the magnesium metal is activated. Therefore, since the ion conductivity of the electrolyte is improved, excellent electrochemical activity can be obtained in the electrolyte.

[0084] In particular, when the polycyclic aromatic hydrocarbons contain acene, the electrochemical activity is sufficiently improved, and thus a higher effect can be obtained.

[0085] In addition, if the solvent of the electrolytic solution contains an ether compound, the electrolyte salt is fully dissolved or dispersed in the solvent, thereby obtaining a higher effect. In this case, if the ether compound contains dimethoxyethane, the electrolyte salt is stably dissolved or dispersed, thereby obtaining a further higher effect.

[0086] <1-4. Electrochemical activity of electrolyte for magnesium batteries>

[0087] Here, by referring to Figure 1 , the electrochemical activity of the electrolyte is described in detail. Figure 1 An example of analysis results (cyclic voltammogram) of an electrolyte solution using cyclic voltammetry is shown.

[0088] Cyclic voltammetry is an analytical method that measures the current while scanning the potential of the electrolyte. Figure 1 As shown, the horizontal axis represents the potential E (V), and the vertical axis represents the current density A (mA / cm 2 ).

[0089] The analysis conditions of the electrolyte were as follows: analysis environment = argon atmosphere, working electrode = platinum, reference electrode = magnesium, counter electrode = magnesium, scanning range = -1 V to 2 V, scanning speed = 25 mV / sec, number of cycles = 5 cycles.

[0090] In this cyclic voltammogram, Figure 1 It can be seen that if the potential E is scanned in the negative direction, the absolute value of the current density A increases and then decreases, thereby generating a reduction wave W2, and if the potential E is scanned in the positive direction, the absolute value of the current density A increases and then decreases, thereby generating an oxidation wave W1. The oxidation wave W1 represents the change in the current density A during the dissolution process, and the reduction wave W2 represents the change in the current density A during the precipitation process.

[0091] Here, the maximum value of the current density A in the oxidation wave W1 (dissolution process) is defined as the maximum dissolution current density AX (mA / cm 2 ), the minimum value of the current density A in the reduction wave W2 (precipitation process) is set as the maximum precipitation current density AY (mA / cm 2 ). The maximum dissolution current density AX and the maximum deposition current density AY are indices indicating the reaction rate, that is, indices indicating the ease of reaction (so-called activity).

[0092] In addition, the potential E1 at which the absolute value of the current density A starts to increase when the potential E is swept in the positive direction is compared with the potential E2 at which the absolute value of the current density A increases and then decreases to 0 mA / cm when the potential E is swept in the negative direction. 2 The difference between the potential E1 and the potential E2 (= E1-E2) is taken as the deposition overvoltage EZ (V). The deposition overvoltage EZ is an index indicating the activity of the surface of the magnesium metal, that is, another index indicating the ease of occurrence of the reaction (so-called activity).

[0093] Thus, from the analysis results (cyclic voltammogram) of the electrolyte solution using cyclic voltammetry, the electrochemical activity of the electrolyte solution can be evaluated based on three indicators: maximum dissolution current density AX, maximum deposition current density AY, and deposition overvoltage EZ.

[0094] When the electrolyte does not contain an additive or contains other additives, the absolute values ​​of the maximum dissolution current density AX and the maximum deposition current density AY decrease, and the deposition overvoltage EZ increases, so that sufficient electrochemical activity cannot be obtained.

[0095] On the other hand, when the electrolyte solution contains the additive, the absolute values ​​of the maximum dissolution current density AX and the maximum deposition current density AY increase, and the deposition overvoltage EZ decreases, so that sufficient electrochemical activity can be obtained.

[0096] <2. Magnesium battery>

[0097] Next, a magnesium battery using the above-mentioned electrolyte solution will be described.

[0098] The magnesium battery described here includes a positive electrode, a negative electrode, and an electrolyte solution, and the electrolyte solution has the above-mentioned structure.

[0099] <2-1. Structure>

[0100] Figure 2 The cross-sectional structure of a magnesium battery is schematically shown. Figure 2 As shown, the magnesium battery includes a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte solution (not shown).

[0101] [positive electrode]

[0102] The positive electrode 10 includes a positive electrode current collector and a positive electrode active material layer (not shown). The positive electrode current collector may be omitted.

[0103] The positive electrode current collector is a conductive support for supporting the positive electrode active material layer, and includes a conductive material such as nickel. The positive electrode active material layer is arranged on the positive electrode current collector, and includes any one or two or more of the positive electrode active materials that embed and de-embed magnesium ions. In addition, the positive electrode active material layer may further include any one or two or more of other materials such as a positive electrode binder and a positive electrode conductive agent.

[0104] The type of positive electrode active material is not particularly limited, and specifically includes sulfur, graphite fluoride, metal oxides, metal halides, etc. The metal oxides and metal halides contain any one or two or more of metal elements such as scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc as constituent elements.

[0105] The positive electrode binder includes any one or more of resin materials such as fluorine resin, polyvinyl alcohol resin and styrene butadiene copolymer rubber. Specific examples of fluorine resin are polyvinylidene fluoride and polytetrafluoroethylene. It should be noted that the positive electrode binder can be a conductive polymer compound. Specific examples of conductive polymer compounds are polyaniline, polypyrrole and polythiophene, etc., or copolymers of two or more thereof. The conductive polymer compound can be unsubstituted or substituted by any one or more functional groups.

[0106] The positive electrode conductive agent includes any one or more of carbon materials, and specific examples of the carbon materials are graphite, carbon fiber, carbon black, and carbon nanotubes. Carbon fiber is vapor grown carbon fiber (VGCF), etc. Carbon black is acetylene black and Ketjen black, etc. Carbon nanotubes are single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT), etc. The multi-walled carbon nanotubes are double-walled carbon nanotubes (DWCNT), etc. In addition, the positive electrode conductive agent can also be a metal material and a conductive polymer compound in addition to the carbon material. Specific examples of metal materials are nickel, etc.

[0107] [negative electrode]

[0108] The negative electrode 20 faces the positive electrode 10 via the separator 30. The negative electrode 20 includes a negative electrode current collector and a negative electrode active material layer (not shown). The negative electrode current collector may be omitted.

[0109] The negative electrode current collector is a conductive support for supporting the negative electrode active material layer, and includes a conductive material such as copper. The negative electrode active material layer is disposed on the negative electrode current collector and includes any one or more of magnesium-based materials. In addition, the negative electrode active material layer may further include any one or more of other materials such as a negative electrode binder and a negative electrode conductive agent.

[0110] Magnesium-based materials are a general term for materials containing magnesium as a constituent element. That is, magnesium-based materials can be a single magnesium, a magnesium alloy, a magnesium compound, or a mixture of two or more thereof. The purity of the single magnesium is not particularly limited, so the single magnesium may contain any amount of impurities. The types of metal elements (except magnesium) contained as constituent elements in magnesium alloys are not particularly limited. Magnesium compounds contain any one or more of non-metallic elements such as carbon, oxygen, sulfur, and halogens as constituent elements. Specific examples of the halogens are fluorine, chlorine, bromine, and iodine.

[0111] [Diaphragm]

[0112] The separator 30 is an insulating porous film interposed between the positive electrode 10 and the negative electrode 20, and allows magnesium ions to pass therethrough while preventing contact (short circuit) between the positive electrode 10 and the negative electrode 20. The separator 30 includes a polymer compound such as polyethylene.

[0113] [Electrolyte]

[0114] The electrolytic solution is a liquid electrolyte impregnated in the separator 30 and has the above-mentioned configuration. That is, the electrolytic solution contains a solvent, an electrolyte salt, and an additive.

[0115] [Other components]

[0116] It should be noted that the magnesium battery may further include any one or two or more of other components. Specific examples of other components include an outer casing, a positive electrode lead, and a negative electrode lead.

[0117] The outer packaging member is a member that accommodates the positive electrode 10, the negative electrode 20, and the separator 30. The type of the outer packaging member is not particularly limited as long as it can accommodate the positive electrode 10, the negative electrode 20, and the separator 30. That is, the outer packaging member may be a rigid can or a flexible or flexible film.

[0118] It should be noted that in Figure 1In order to simplify the content of the figure, detailed illustrations are omitted, but the positive electrode 10, the negative electrode 20 and the separator 30 can form a winding structure or a stacked structure. In the winding structure, the positive electrode 10 and the negative electrode 20 are opposite to each other and wound with the separator 30 interposed therebetween. In the stacked structure, the positive electrode 10 and the negative electrode 20 are alternately stacked with the separator 30 interposed therebetween.

[0119] The positive electrode lead is a terminal for external connection of the positive electrode 10, and the negative electrode lead is a terminal for external connection of the negative electrode 20. One end of the positive electrode lead is connected to the positive electrode 10, and the other end of the positive electrode lead is led out of the outer packaging member. One end of the negative electrode lead is connected to the negative electrode 20, and the other end of the negative electrode lead is led out of the outer packaging member.

[0120] <2-2. Action>

[0121] When the magnesium battery is charged, magnesium is released from the positive electrode 10 and is inserted into the negative electrode 20 via the electrolyte. On the other hand, when the magnesium battery is discharged, magnesium is released from the negative electrode 20 and is inserted into the positive electrode 10 via the electrolyte. During these charge and discharge, magnesium is inserted and released in an ionic state.

[0122] <2-3. Functions and effects>

[0123] According to the magnesium battery, the magnesium battery includes an electrolyte having the above-mentioned structure. In this case, due to the above-mentioned reasons, excellent electrochemical activity can be obtained in the electrolyte. Therefore, a magnesium battery with excellent battery characteristics can be realized.

[0124] Other functions and effects of the magnesium battery are the same as those of the above-mentioned electrolyte.

[0125] <3. Applications of magnesium batteries>

[0126] The use (application examples) of magnesium batteries are not particularly limited. In electronic devices and electric vehicles, the secondary battery used as a power source can be a main power source or an auxiliary power source. The main power source is the power source that is used preferentially, regardless of the presence or absence of other power sources. The auxiliary power source can be a power source that is used instead of the main power source, or a power source that is switched from the main power source.

[0127] Specific examples of the uses of magnesium batteries are as follows. Electronic devices such as video cameras, digital still cameras, mobile phones, laptop computers, stereo headphones, portable radios, and portable information terminals. Storage devices such as backup power supplies and memory cards. Power tools such as electric drills and electric saws. Battery packs installed in electronic devices, etc. Medical electronic devices such as pacemakers and hearing aids. Electric vehicles such as electric vehicles (including hybrid vehicles). Power storage systems such as battery systems for home or industrial use that store electricity in advance in preparation for emergencies, etc. In these uses, one magnesium battery or multiple magnesium batteries can be used.

[0128] The battery pack may use a single cell or a battery pack. An electric vehicle is a vehicle that uses a magnesium battery as a driving power source, or a hybrid vehicle that also has a driving source other than the magnesium battery. In a home power storage system, the power stored in the magnesium battery as a power storage source can be used to use home electrical products, etc.

[0129] Example

[0130] Embodiments of the present technology will be described.

[0131] <Examples 1 to 3 and Comparative Examples 1 and 2>

[0132] As described below, after the electrolyte solution was produced, the physical properties of the electrolyte solution were evaluated.

[0133] [Manufacturing of electrolyte]

[0134] First, an electrolyte salt (Mg[B(OCH(CF3)2)4]2(MgBOF) as a magnesium salt) was added to a solvent (dimethoxyethane as an ether compound), and then the solvent was stirred using a stirrer to prepare a solution. In this case, the content of the electrolyte salt was 0.3 mol / dm 3 .

[0135] Next, after adding additives to the solution, the solution was stirred using a stirrer. As the additives, Mg[N(Si(CH3)3)2]2 (MgNS) as the first magnesium compound, Mg(BH4)2 (MgBH) as the second magnesium compound, and anthracene (ANT) as the polycyclic aromatic hydrocarbon were used. In this case, the content of the first magnesium compound in the solution was set to 0.15 mol / dm 3 , and the content of the second magnesium compound and the polycyclic aromatic hydrocarbons in the solution is 0.01 mol / dm 3 .

[0136] Finally, the solution was filtered, thereby preparing an electrolyte solution containing a solvent, an electrolyte salt, and an additive.

[0137] Here, for comparison, the electrolyte solution was prepared by the same procedure except that no additive was used. Also, for comparison, the electrolyte solution was prepared by the same procedure except that another additive (magnesium chloride (MgCl2)) was used instead of the additive. In this case, the content of the other additive in the solution was 0.15 mol / dm 3 .

[0138] It should be noted that after the electrolyte solution was prepared, the type of electrolyte salt (magnesium salt) and the content of electrolyte salt in the electrolyte solution, the type of additives and the content of additives in the electrolyte solution, and the type of other additives and the content of other additives in the electrolyte solution were determined using ICP emission spectrometry. The results are as described above.

[0139] [Evaluation of physical properties]

[0140] The electrochemical activity of the electrolyte solution was evaluated, and the results shown in Table 1 were obtained.

[0141] In order to evaluate the electrochemical activity of the electrolyte, the electrolyte was analyzed by cyclic voltammetry, and then the maximum dissolution current density AX (mA / cm 2 )、Maximum deposition current density AY(mA / cm 2 ) and the precipitation overvoltage EZ (V).

[0142] The analysis conditions of the electrolyte solution using cyclic voltammetry and the procedures for respectively determining the maximum dissolution current density AX, the maximum deposition current density AY, and the deposition overvoltage EZ are as described above.

[0143] [Table 1]

[0144]

[0145] [Investigation]

[0146] As shown in Table 1, the electrochemical activity of the electrolyte solution varies greatly depending on the composition of the electrolyte solution.

[0147] Specifically, when the electrolyte solution contains neither additives nor other additives (Comparative Example 1), the absolute value of each of the maximum dissolution current density AX and the maximum deposition current density AY is 0 mA / cm 2 . Therefore, the electrolyte is electrochemically inactive.

[0148] In addition, when the electrolyte contains other additives (Comparative Example 2), the absolute values ​​of the maximum dissolution current density AX and the maximum deposition current density AY are slightly increased, and the deposition overvoltage EZ is slightly reduced compared to the case where the electrolyte does not contain other additives (Comparative Example 1). However, the absolute values ​​of the maximum dissolution current density AX and the maximum deposition current density AY are not sufficiently increased, and the deposition overvoltage EZ is not sufficiently reduced. Therefore, the electrolyte is not sufficiently active electrochemically.

[0149] In contrast, when the electrolyte contains additives (Examples 1 to 3), the absolute values ​​of the maximum dissolution current density AX and the maximum deposition current density AY are greatly increased, and the deposition overvoltage EZ is greatly reduced, compared with the case where the electrolyte does not contain additives (Comparative Example 1). As a result, the maximum dissolution current density AX and the maximum deposition current density AY are sufficiently increased, and the deposition overvoltage EZ is sufficiently reduced. Therefore, the electrolyte is electrochemically sufficiently active.

[0150] [Summarize]

[0151] According to the results shown in Table 1, when the electrolyte solution contains an electrolyte salt and an additive, the electrolyte salt contains the above-mentioned magnesium salt, and the additive contains any one or more of the above-mentioned first magnesium compound, second magnesium compound and polycyclic aromatic hydrocarbons, the electrochemical activity is improved. Therefore, in the electrolyte solution containing magnesium salt as the electrolyte salt, excellent electrochemical activity is obtained.

[0152] Although the present technology has been described above by taking one embodiment and one example, the configuration of the present technology is not limited to the configuration described in these embodiments and examples, and various modifications are possible.

[0153] The effects described in this specification are merely examples, and therefore the effects of the present technology are not limited to the effects described in this specification. Therefore, other effects can also be obtained with respect to the present technology.

[0154] It should be noted that the present technology can also adopt the following structures.

[0155] <1>

[0156] An electrolyte for a magnesium battery,

[0157] Contains solvents, electrolyte salts and additives,

[0158] The electrolyte salt comprises a magnesium salt represented by formula (1),

[0159] The additive includes at least one of a first magnesium compound represented by formula (2), a second magnesium compound represented by formula (3), and a polycyclic aromatic hydrocarbon.

[0160] Mg[B(OC(R1)3)4]2…(1)

[0161] (The 24 R1s are each any one of hydrogen (H), fluorine (F), an alkyl group, and a fluorinated alkyl group. At least one of the 24 R1s is any one of fluorine and a fluorinated alkyl group.)

[0162] Mg[N(Si(R2)3)2)]2…(2)

[0163] (Each of the 12 R2s is either hydrogen or an alkyl group.)

[0164] Mg(R3)2…(3)

[0165] (The two R3 are either hydrogen or boron hydride (BH4).

[0166] <2>

[0167] The magnesium battery electrolyte according to <1>,

[0168] The polycyclic aromatic hydrocarbons include acene.

[0169] <3>

[0170] The magnesium battery electrolyte according to <1> or <2>,

[0171] The solvent includes an ether compound having an ether bond (—O—).

[0172] <4>

[0173] The magnesium battery electrolyte according to <3>,

[0174] The ether compound includes dimethoxyethane.

[0175] <5>

[0176] A magnesium battery,

[0177] It has positive electrode, negative electrode and electrolyte for magnesium battery.

[0178] The magnesium battery electrolyte comprises a solvent, an electrolyte salt and an additive.

[0179] The electrolyte salt comprises a magnesium salt represented by formula (1),

[0180] The additive includes at least one of a first magnesium compound represented by formula (2), a second magnesium compound represented by formula (3), and a polycyclic aromatic hydrocarbon.

[0181] Mg[B(OC(R1)3)4]2…(1)

[0182] (The 24 R1s are each any one of hydrogen (H), fluorine (F), an alkyl group, and a fluorinated alkyl group. At least one of the 24 R1s is any one of fluorine and a fluorinated alkyl group.)

[0183] Mg[N(Si(R2)3)2)]2…(2)

[0184] (Each of the 12 R2s is either hydrogen or an alkyl group.)

[0185] Mg(R3)2…(3)

[0186] (The two R3 are either hydrogen or boron hydride (BH4).

Claims

1. An electrolyte for a magnesium battery, comprising a solvent, an electrolyte salt and an additive, The electrolyte salt comprises a magnesium salt represented by formula (1), The additive comprises at least one of a first magnesium compound represented by formula (2), a second magnesium compound represented by formula (3), and a polycyclic aromatic hydrocarbon. Mg[B(OC(R1)3)4]2…(1) 24 R1 are each any one of hydrogen (H), fluorine (F), alkyl and fluorinated alkyl, wherein: At least one of the 24 R1s is any one of fluorine and fluorinated alkyl, Mg[N(Si(R2)3)2]2…(2) 12 R2 are each hydrogen or alkyl, Mg(R3)2…(3) The two R3's are either hydrogen or boron hydride, that is, BH4.

2. The electrolyte for magnesium battery according to claim 1, wherein The polycyclic aromatic hydrocarbons include acene.

3. The electrolyte for magnesium battery according to claim 1 or 2, wherein The solvent includes an ether compound having an ether bond, ie, -O-.

4. The electrolyte for magnesium battery according to claim 3, wherein The ether compound includes dimethoxyethane.

5. A magnesium battery comprising a positive electrode, a negative electrode and an electrolyte for a magnesium battery, The magnesium battery electrolyte comprises a solvent, an electrolyte salt and an additive. The electrolyte salt comprises a magnesium salt represented by formula (1), The additive comprises at least one of a first magnesium compound represented by formula (2), a second magnesium compound represented by formula (3), and a polycyclic aromatic hydrocarbon. Mg[B(OC(R1)3)4]2…(1) 24 R1 are each any one of hydrogen (H), fluorine (F), alkyl and fluorinated alkyl, wherein: At least one of the 24 R1s is any one of fluorine and fluorinated alkyl, Mg[N(Si(R2)3)2]2…(2) 12 R2 are each hydrogen or alkyl, Mg(R3)2…(3) The two R3's are either hydrogen or boron hydride, that is, BH4.

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