Magnesium battery electrolyte and magnesium battery

Abstract

This electrolyte solution for magnesium batteries contains a solvent, an electrolyte salt and an additive. The electrolyte salt contains a magnesium salt that is represented by formula (1). The additive contains at least one substance that is selected from among a first magnesium compound represented by formula (2), a second magnesium compound represented by formula (3) and a polycyclic aromatic hydrocarbon.　(1): Mg(B(OC(R1)3)4)2 (In the formula, each one of 24 R1 moieties represents a hydrogen atom (H), a fluorine atom (F), an alkyl group or a fluorinated alkyl group; and at least one of the 24 R1 moieties represents either a fluorine atom or a fluorinated alkyl group.)　(2): Mg((N(Si(R2)3)2)2 (In the formula, each one of 12 R2 moieties represents either a hydrogen atom or an alkyl group.)　(3): Mg(R2)2 (In the formula, each one of two R3 moieties represents either a hydrogen atom or boron hydride (BH4.)

Description

[Technical Field]

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

[0002] The development of magnesium batteries is underway. These magnesium batteries include a positive electrode, a negative electrode, and an electrolyte (magnesium battery electrolyte), and the electrolyte contains magnesium salt as the electrolyte salt.

[0003] Several techniques related to the construction of magnesium batteries are already known. Specifically, magnesium salt (Mg[B(OCH(CF3)2)4]2) has been synthesized using a magnesium compound (Mg(BH4)2) as a raw material (see, for example, Non-Patent Document 1), and an electrolyte using this magnesium salt has been proposed (see, for example, Non-Patent Document 2). In addition, a specific anion (B(OCH(CF3)2)4 - An electrolyte solution containing ammonium nitrate (ANO) and magnesium chloride (MgCl2) has been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 08-171916 [Non-patent literature]

[0005] [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 [Non-patent document 2] Critical Issues of Fluorinated Alkoxyborate-Based Electrolytes in Magnesium Battery Applications,ACS Appl. Mater. Interfaces 2020, 12, 39135-39144 Summary of the Invention

[0006] Although various studies have been conducted on the configuration of magnesium batteries, the electrochemical activity of the electrolyte used in the magnesium batteries is still insufficient, and there is room for improvement.

[0007] There is a demand for a magnesium battery electrolyte and a magnesium battery that can provide excellent electrochemical activity.

[0008] According to one embodiment of the present technology, an electrolyte solution for a magnesium battery 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.

[0009] Mg[B(OC(R1)3)4]2 (1) (Each of the 24 R1 is either hydrogen (H), fluorine (F), an alkyl group, or a fluorinated alkyl group, provided that at least one of the 24 R1 is either fluorine or a fluorinated alkyl group.)

[0010] Mg[(N(Si(R2)3)2]2···(2) (Each of the 12 R2 is either hydrogen or an alkyl group.)

[0011] Mg(R3)2 (3) (Each of the two R3 is either hydrogen or boron hydride (BH4).)

[0012] A magnesium battery according to one embodiment of the present technology includes a positive electrode, a negative electrode, and a magnesium battery electrolyte, and the magnesium battery electrolyte has a configuration similar to the configuration of the magnesium battery electrolyte according to the embodiment of the present technology described above.

[0013] According to the magnesium battery electrolyte or magnesium battery of one embodiment of the present technology, the magnesium battery electrolyte 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, second magnesium compound, and polycyclic aromatic hydrocarbon, so that excellent electrochemical activity can be obtained.

[0014] Note that the effects of the present technology are not necessarily limited to the effects described here, but may be any of a series of effects related to the present technology described below. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is an example of an analysis result (cyclic voltammogram) of an electrolyte solution using cyclic voltammetry. [Figure 2] 1 is a cross-sectional view schematically illustrating a configuration of a magnesium battery according to an embodiment of the present technology. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present technology will be described in detail with reference to the drawings. The description will be made in the following order. 1. Magnesium battery electrolyte 1-1.Configuration 1-2. Manufacturing method 1-3. Action and effects 1-4. Electrochemical activity of electrolytes for magnesium batteries 2. Magnesium battery 2-1.Configuration 2-2.Operation 2-3. Action and effects 3. Applications of magnesium batteries

[0017] <1. Electrolyte for magnesium batteries> First, an electrolyte solution for a magnesium battery (hereinafter simply referred to as "electrolyte solution") according to one embodiment of the present technology will be described.

[0018] The electrolyte solution described here is a liquid electrolyte and is used in magnesium batteries. However, the use of the electrolyte solution is not limited to magnesium batteries, and the electrolyte solution may be used for purposes other than magnesium batteries.

[0019] <1-1.Configuration> The electrolyte solution contains a solvent, an electrolyte salt, and an additive.

[0020] [solvent] The solvent is a material that dissolves or disperses the electrolyte salt, and is one or more kinds of organic solvents.

[0021] The type of solvent is not particularly limited, but it is preferable that the solvent contains an ether compound, since this allows the electrolyte salt to be sufficiently dissolved or dispersed.

[0022] The term "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 include dimethoxyethane, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and tetrahydrofuran. This is because the electrolyte salt is stably dissolved or dispersed in these compounds. Specific examples of the series of ether compounds described here are mainly so-called glyme-based ethers.

[0023] [Electrolyte salt] The electrolyte salt is a substance that ionizes in a solvent and contains a magnesium salt. Specifically, the magnesium salt contains one or more compounds represented by formula (1).

[0024] Mg[B(OC(R1)3)4]2 (1) (Each of the 24 R1 is either hydrogen (H), fluorine (F), an alkyl group, or a fluorinated alkyl group, provided that at least one of the 24 R1 is either fluorine or a fluorinated alkyl group.)

[0025] As is clear from formula (1), this magnesium salt contains magnesium ions (Mg 2+ ) and two boron-containing ions ([B(OC(R1)3)4] - ) is a salt containing

[0026] As described above, each of the 24 R1 is not particularly limited as long as it is any one of hydrogen, fluorine, an alkyl group, and a fluorinated alkyl group. However, one or more of the 24 R1 are any one of fluorine and a fluorinated alkyl group. Therefore, a compound in which all of the 24 R1 are any one of hydrogen and an alkyl group does not fall under the magnesium salt described here.

[0027] The number of carbon atoms in the alkyl group is not particularly limited. The type of alkyl group may be linear or branched. Specific examples of the alkyl group include a methyl group and an ethyl group. Of these, the alkyl group is preferably a methyl group, as this improves the solubility of the magnesium salt.

[0028] A fluorinated alkyl group is an alkyl group in which one or more hydrogen atoms have been substituted with fluorine atoms. The number of carbon atoms in the fluorinated alkyl group is not particularly limited, and the number of fluorine atoms contained in the fluorinated alkyl group is also not particularly limited.

[0029] 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(OCF(CH3)2)4]2 and Mg[B(OCF(CF3)2)4]2.

[0030] The content (mol / kg) of the electrolyte salt in the electrolytic solution is not particularly limited and can be set arbitrarily. The content of the electrolyte salt described here is the content of the electrolyte salt relative to the solvent.

[0031] [Additives] The additive contains one or more of a first magnesium compound, a second magnesium compound, and a polycyclic aromatic hydrocarbon.

[0032] The electrolyte contains an additive because the electrochemical activity of the electrolyte containing the electrolyte salt (magnesium salt) is significantly improved compared to when the electrolyte does not contain the additive or when the electrolyte contains other additives.

[0033] In particular, if the electrolyte does not contain additives, sufficient electrochemical activity may not be achieved, and in some cases no electrochemical activity may be achieved at all.

[0034] Furthermore, when the electrolyte contains other additives in addition to the magnesium salt, the electrochemical activity is slightly improved compared to when the electrolyte does not contain any 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).

[0035] On the other hand, if the electrolyte contains an additive together with the magnesium salt, 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 ionic conductivity of the electrolyte and providing excellent electrochemical activity.

[0036] The content (wt%) 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 sum of the contents of the two or more additives.

[0037] (first magnesium compound) The first magnesium compound contains one or more of the compounds represented by formula (2).

[0038] Mg[(N(Si(R2)3)2]2···(2) (Each of the 12 R2 is either hydrogen or an alkyl group.)

[0039] As is clear from formula (2), this first magnesium compound is a compound in which two bis(trimethylsilyl)amine type groups (-N(SiR23)2) are bonded to a magnesium atom.

[0040] As described above, each of the twelve R2 is not particularly limited as long as it is either hydrogen or an alkyl group. 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 a methyl group and an ethyl group.

[0041] A specific example of the first magnesium compound is Mg[(CH3)3Si-N-Si(CH3)3]2.

[0042] (secondary magnesium compounds) The second magnesium compound contains one or more of the compounds represented by formula (3).

[0043] Mg(R3)2 (3) (Each of the two R3 is either hydrogen or boron hydride (BH4).)

[0044] As is clear from formula (3), this second magnesium compound is a compound in which two hydrogen-containing groups (R3) are bonded to a magnesium atom. As described above, each of the two R3 is not particularly limited as long as it is either hydrogen or boron hydride.

[0045] Specific examples of the second magnesium compound are MgH2 and Mg(BH4)2.

[0046] (Polycyclic aromatic hydrocarbons) Polycyclic aromatic hydrocarbons are a general term for hydrocarbons in which two or more aromatic rings (benzene rings) containing no heteroatoms or substituents are condensed. The type of polycyclic aromatic hydrocarbon may be one type or two or more types.

[0047] In this 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. Furthermore, the two or more aromatic rings may be condensed in a linear or non-linear manner.

[0048] Specific examples of polycyclic aromatic hydrocarbons in which two or more aromatic rings are linearly fused include naphthalene, anthracene, tetracene, pentacene, hexacene, and heptacene. Specific examples of polycyclic aromatic hydrocarbons in which two or more aromatic rings are nonlinearly fused include phenanthrene, chrysene, pyrene, triphenylene, benzopyrene, corannulene, coronene, and covalene.

[0049] Among them, it is preferable that the polycyclic aromatic hydrocarbon contains an acene, because this sufficiently improves the electrochemical activity of the electrolyte. Specific examples of acenes include the above-mentioned naphthalene, anthracene, tetracene, pentacene, hexacene, and heptacene.

[0050] <1-2. Manufacturing method> When producing an electrolytic solution, an electrolyte salt containing a magnesium salt is added to a solvent, and then an additive is added to the solvent. In this case, one or more of a first magnesium compound, a second magnesium compound, and a polycyclic aromatic hydrocarbon are used as the additive. As a result, the electrolyte salt and the additive are dissolved or dispersed in the solvent, thereby preparing the electrolytic solution.

[0051] <1-3. Actions and Effects> According to this electrolytic solution, the electrolytic 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 ring hydrocarbon.

[0052] In this case, as described above, compared with the case where the electrolyte does not contain any additive or the case where the electrolyte contains other additives, 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 ionic conductivity of the electrolyte and achieving excellent electrochemical activity in the electrolyte.

[0053] In particular, if the polycyclic aromatic hydrocarbon contains an acene, the electrochemical activity is sufficiently improved, and therefore a higher effect can be obtained.

[0054] Furthermore, if the solvent of the electrolytic solution contains an ether compound, the electrolyte salt is sufficiently dissolved or dispersed in the solvent, resulting in a higher effect. In this case, if the ether compound contains dimethoxyethane, the electrolyte salt is stably dissolved or dispersed, resulting in an even higher effect.

[0055] <1-4. Electrochemical activity of electrolytes for magnesium batteries> Here, the electrochemical activity of the electrolyte will be described in detail with reference to Fig. 1. Fig. 1 shows an example of the analysis results (cyclic voltammogram) of the electrolyte using cyclic voltammetry.

[0056] Cyclic voltammetry is an analytical method in which the current is measured while sweeping the potential of an electrolyte. In a cyclic voltammogram, as shown in Figure 1, the horizontal axis represents the potential E (V) and the vertical axis represents the current density A (mA / cm 2 )

[0057] The analysis conditions for the electrolyte were as follows: analysis environment = argon gas atmosphere, working electrode = platinum, reference electrode = magnesium, counter electrode = magnesium, sweep range = -1 V to 2 V, sweep rate = 25 mV / sec, number of cycles = 5 cycles.

[0058] In this cyclic voltammogram, as is clear from Figure 1, when the potential E is swept in the negative direction, the absolute value of the current density A increases and then decreases, resulting in the generation of a reduction wave W2, and when the potential E is swept in the positive direction, the absolute value of the current density A increases and then decreases, resulting in the generation of an oxidation wave W1. The oxidation wave W1 represents the change in current density A during the dissolution process, and the reduction wave W2 represents the change in current density A during the precipitation process.

[0059] Here, the maximum value of the current density A in the oxidation wave W1 (dissolution process) is the maximum dissolution current density AX (mA / cm 2 ), the minimum value of the current density A in the reduction wave W2 (deposition process) is taken as the maximum deposition current density AY (mA / cm 2The maximum dissolution current density AX and the maximum deposition current density AY are each an index representing the reaction rate, that is, an index representing the ease with which the reaction occurs (so-called activity).

[0060] In addition, when the potential E is swept in the positive direction, the absolute value of the current density A begins to increase at potential E1, and when the potential E is swept in the negative direction, the absolute value of the current density A increases, then decreases, and reaches 0 mA / cm 2 The difference between the potential E1 and the potential E2 at which this occurs (= E1 - E2) is defined as the deposition overpotential EZ (V). This deposition overpotential EZ is an index that indicates the activity of the magnesium metal surface, that is, another index that indicates the ease with which a reaction occurs (so-called activity).

[0061] As a result, the analysis results of the electrolyte using cyclic voltammetry (cyclic voltammogram) can be used to evaluate the electrochemical activity of the electrolyte based on three indices: maximum dissolution current density AX, maximum deposition current density AY, and deposition overpotential EZ.

[0062] When the electrolyte does not contain any additives 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 overpotential EZ increases, resulting in insufficient electrochemical activity.

[0063] On the other hand, when the electrolyte contains an additive, the absolute values ​​of the maximum dissolution current density AX and the maximum deposition current density AY increase, and the deposition overpotential EZ decreases, thereby achieving sufficient electrochemical activity.

[0064] <2. Magnesium battery> Next, a magnesium battery using the above-mentioned electrolyte will be described.

[0065] The magnesium battery described here includes a positive electrode, a negative electrode, and an electrolyte, and the electrolyte has the above-described composition.

[0066] <2-1.Configuration> Fig. 2 shows a schematic cross-sectional configuration of a magnesium battery. As shown in Fig. 2, this magnesium battery includes a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte (not shown).

[0067] [Positive electrode] The positive electrode 10 includes a positive electrode current collector and a positive electrode active material layer (not shown), although the positive electrode current collector may be omitted.

[0068] The positive electrode current collector is a conductive support that supports the positive electrode active material layer and contains a conductive material such as nickel. The positive electrode active material layer is provided on the positive electrode current collector and contains one or more positive electrode active materials that absorb and release magnesium ions. However, the positive electrode active material layer may further contain one or more other materials such as a positive electrode binder and a positive electrode conductive agent.

[0069] The type of positive electrode active material is not particularly limited, but specific examples include sulfur, graphite fluoride, metal oxides, metal halides, etc. Each of the metal oxides and metal halides contains one or more of the metal elements such as scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc as a constituent element.

[0070] The positive electrode binder contains one or more of the following resin materials: fluorine-based resin, polyvinyl alcohol-based resin, and styrene-butadiene copolymer rubber. Specific examples of fluorine-based resin include polyvinylidene fluoride and polytetrafluoroethylene. The positive electrode binder may be a conductive polymer compound. Specific examples of the conductive polymer compound include polyaniline, polypyrrole, and polythiophene, and may be a copolymer of two or more of these. The conductive polymer compound may be unsubstituted or substituted with one or more functional groups.

[0071] The positive electrode conductive agent contains one or more types of carbon materials, and specific examples of the carbon materials include graphite, carbon fiber, carbon black, and carbon nanotubes. Carbon fiber includes vapor-grown carbon fiber (VGCF). Carbon black includes acetylene black and ketjen black. Carbon nanotubes include single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT), and multi-walled carbon nanotubes include double-walled carbon nanotubes (DWCNT). However, the positive electrode conductive agent may be a metal material or a conductive polymer compound in addition to a carbon material. A specific example of a metal material is nickel.

[0072] [Negative electrode] The negative electrode 20 faces the positive electrode 10 via a separator 30. The negative electrode 20 includes a negative electrode current collector and a negative electrode active material layer (not shown). However, the negative electrode current collector may be omitted.

[0073] The negative electrode current collector is a conductive support that supports the negative electrode active material layer and contains a conductive material such as copper. The negative electrode active material layer is provided on the negative electrode current collector and contains one or more magnesium-based materials. However, the negative electrode active material layer may further contain one or more other materials such as a negative electrode binder and a negative electrode conductive agent.

[0074] Magnesium-based materials are a general term for materials containing magnesium as a constituent element. That is, magnesium-based materials may be magnesium alone, magnesium alloys, magnesium compounds, or mixtures of two or more of these. The purity of magnesium alone is not particularly limited, and the magnesium alone may contain any amount of impurities. The types of metal elements (excluding magnesium) contained as constituent elements in magnesium alloys are not particularly limited. Magnesium compounds contain one or more non-metallic elements such as carbon, oxygen, sulfur, and halogens as constituent elements. Specific examples of halogens include fluorine, chlorine, bromine, and iodine.

[0075] [Separator] 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 through while preventing contact (short circuit) between the positive electrode 10 and the negative electrode 20. The separator 30 contains a polymer compound such as polyethylene.

[0076] [Electrolyte] The electrolytic solution is a liquid electrolyte impregnated in the separator 30 and has the above-described composition. That is, the electrolytic solution contains a solvent, an electrolyte salt, and an additive.

[0077] [Other components] The magnesium battery may further include one or more of the other components, such as an exterior member, a positive electrode lead, and a negative electrode lead.

[0078] The exterior member is a member that houses the positive electrode 10, the negative electrode 20, the separator 30, etc. The type of exterior member is not particularly limited as long as it is a member that can house the positive electrode 10, the negative electrode 20, the separator 30, etc. In other words, the exterior member may be a rigid can or a flexible or pliable film.

[0079] 1, for the sake of simplicity, detailed illustration is omitted, but the positive electrode 10, the negative electrode 20, and the separator 30 may form a wound structure or a stacked structure. In the wound structure, the positive electrode 10 and the negative electrode 20 are wound while facing each other 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.

[0080] 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 exterior 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 exterior member.

[0081] <2-2. Operation> When the magnesium battery is charged, magnesium is released from the positive electrode 10 and is absorbed 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 absorbed into the positive electrode 10 via the electrolyte. During charging and discharging, magnesium is absorbed and released in an ionic state.

[0082] <2-3. Actions and Effects> According to this magnesium battery, the magnesium battery includes an electrolyte solution, and the electrolyte solution has the above-described configuration. In this case, for the above-described reasons, excellent electrochemical activity can be obtained in the electrolyte solution. Therefore, a magnesium battery with excellent battery characteristics can be realized.

[0083] Other functions and effects of the magnesium battery are the same as those of the electrolyte described above.

[0084] <3. Applications of magnesium batteries> There are no particular limitations on the uses (applications) of magnesium batteries. Secondary batteries used as power sources may be the main power source or auxiliary power source in electronic devices, electric vehicles, etc. The main power source is a power source that is used preferentially regardless of the presence or absence of other power sources. The auxiliary power source may be a power source used in place of the main power source or a power source that can be switched from the main power source.

[0085] Specific examples of uses for magnesium batteries are as follows: Electronic devices such as video cameras, digital still cameras, mobile phones, laptop computers, headphone stereos, portable radios, and portable information terminals. Storage devices such as backup power supplies and memory cards. Power tools such as power drills and power saws. Battery packs installed in electronic devices. Medical electronic devices such as pacemakers and hearing aids. Electric vehicles such as electric cars (including hybrid cars). Power storage systems such as home or industrial battery systems that store power in preparation for emergencies. In these uses, one or more magnesium batteries may be used.

[0086] The battery pack may use a single cell or a battery pack. The electric vehicle is a vehicle that runs using a magnesium battery as a driving power source, and may be 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, which is a power storage source, can be used to power home electrical appliances, etc. [Example]

[0087] An embodiment of the present technology will be described.

[0088] <Examples 1 to 3 and Comparative Examples 1 and 2> As described below, after the electrolyte solution was prepared, the physical properties of the electrolyte solution were evaluated.

[0089] [Electrolyte production] First, an electrolyte salt (magnesium salt Mg[B(OCH(CF3)2)4]2(MgBOF)) was added to a solvent (an ether compound, dimethoxyethane), and then the solution was prepared by stirring the solvent using a stirrer. In this case, the content of the electrolyte salt relative to the solvent was 0.3 mol / dm 3 It was decided.

[0090] Subsequently, additives were added to the solution, and the solution was stirred using a stirrer. The additives used were a first magnesium compound, Mg[(N(Si(CH3)3)2)]2 (MgNS), a second magnesium compound, Mg(BH4)2 (MgBH), and anthracene (ANT), a polycyclic aromatic hydrocarbon. In this case, the content of the first magnesium compound in the solution was 0.15 mol / dm 3 The content of the second magnesium compound and the polycyclic aromatic hydrocarbon in the solution was 0.01 mol / dm 3 It was decided.

[0091] Finally, the solution was filtered to prepare an electrolyte solution containing a solvent, an electrolyte salt, and an additive.

[0092] For comparison, an electrolyte solution was prepared using the same procedure except that no additive was used. Also, for comparison, an electrolyte solution was prepared using the same procedure except that another additive (magnesium chloride (MgCl)) was used instead of the additive. In this case, the content of the other additive in the solution was 0.15 mol / dm 3 It was decided.

[0093] After preparing the electrolyte solution, the type of electrolyte salt (magnesium salt) and the content of the electrolyte salt in the electrolyte solution, the type of additive and the content of the additive in the electrolyte solution, and the type of other additive and the content of the other additive in the electrolyte solution were measured using ICP atomic emission spectroscopy, and the results were as described above.

[0094] [Evaluation of physical properties] The electrochemical activity of the electrolyte was evaluated, and the results shown in Table 1 were obtained.

[0095] To evaluate the electrochemical activity of an electrolyte, the electrolyte is analyzed using cyclic voltammetry, and then the maximum dissolution current density AX (mA / cm) is calculated based on the analysis results (cyclic voltammogram) of the electrolyte. 2 ), maximum deposition current density AY (mA / cm 2 ) and deposition overpotential EZ (V), respectively.

[0096] The conditions for analyzing the electrolyte using cyclic voltammetry and the procedures for determining the maximum dissolution current density AX, the maximum deposition current density AY, and the deposition overpotential EZ are as described above.

[0097] [Table 1]

[0098] [Consideration] As shown in Table 1, the electrochemical activity of the electrolyte varied greatly depending on the electrolyte composition.

[0099] Specifically, when the electrolyte does not contain any additives or other additives (Comparative Example 1), the absolute values ​​of the maximum dissolution current density AX and the maximum deposition current density AY are 0 mA / cm 2 Therefore, the electrolyte was not electrochemically active.

[0100] Furthermore, when the electrolyte contained other additives (Comparative Example 2), the absolute values ​​of the maximum dissolution current density AX and the maximum deposition current density AY increased slightly, and the deposition overpotential EZ decreased slightly, compared to when the electrolyte did 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 did not increase sufficiently, and the deposition overpotential EZ did not decrease sufficiently. Therefore, the electrolyte was not sufficiently electrochemically active.

[0101] In contrast, when the electrolyte contained an additive (Examples 1 to 3), the absolute values ​​of the maximum dissolution current density AX and the maximum deposition current density AY increased significantly, and the deposition overpotential EZ decreased significantly, compared to when the electrolyte did not contain an additive (Comparative Example 1). As a result, the maximum dissolution current density AX and the maximum deposition current density AY increased sufficiently, and the deposition overpotential EZ decreased sufficiently. Therefore, the electrolyte became sufficiently electrochemically active.

[0102] [summary] The results shown in Table 1 indicate that the electrochemical activity was improved when the electrolyte solution contained an electrolyte salt and an additive, the electrolyte salt contained the magnesium salt, and the additive contained one or more of the first magnesium compound, the second magnesium compound, and the polycyclic aromatic hydrocarbon. Therefore, excellent electrochemical activity was obtained in the electrolyte solution containing the magnesium salt as the electrolyte salt.

[0103] The present technology has been described above with reference to an embodiment and examples, but the configuration of the present technology is not limited to the configuration described in those embodiment and examples, and can be modified in various ways.

[0104] The effects described in this specification are merely examples, and the effects of the present technology are not limited to the effects described in this specification. Therefore, other effects may be obtained with respect to the present technology.

[0105] The present technology can also be configured as follows. <1> including 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. Magnesium battery electrolyte. Mg[B(OC(R1)3)4]2 (1) (Each of the 24 R1 is either hydrogen (H), fluorine (F), an alkyl group, or a fluorinated alkyl group, provided that at least one of the 24 R1 is either fluorine or a fluorinated alkyl group.) Mg[(N(Si(R2)3)2]2···(2) (Each of the 12 R2 is either hydrogen or an alkyl group.) Mg(R3)2 (3) (Each of the two R3 is either hydrogen or boron hydride (BH4).) <2> The polycyclic aromatic hydrocarbon includes an acene. <1> The magnesium battery electrolyte according to claim 1. <3> The solvent includes an ether compound having an ether bond (—O—). <1> or <2> The magnesium battery electrolyte according to claim 1. <4> The ether compound includes dimethoxyethane. <3> The magnesium battery electrolyte according to claim 1. <5> a positive electrode, a negative electrode, and a magnesium battery electrolyte; The magnesium battery electrolyte solution includes 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. Magnesium battery. Mg[B(OC(R1)3)4]2 (1) (Each of the 24 R1 is either hydrogen (H), fluorine (F), an alkyl group, or a fluorinated alkyl group, provided that at least one of the 24 R1 is either fluorine or a fluorinated alkyl group.) Mg[(N(Si(R2)3)2]2···(2) (Each of the 12 R2 is either hydrogen or an alkyl group.) Mg(R3)2 (3) (Each of the two R3 is either hydrogen or boron hydride (BH4).)

Claims

1. including 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. Electrolyte for magnesium batteries. Mg[B(OC(R1) 3 ) 4 ] 2 ・・・(1) (Each of the 24 R1's is either hydrogen (H), fluorine (F), an alkyl group, or a fluorinated alkyl group, provided that at least one of the 24 R1's is either fluorine or a fluorinated alkyl group.) Mg[(N(Si(R2) 3 ) 2 ] 2 ・・・(2) (Each of the 12 R2 is either hydrogen or an alkyl group.) Mg(R3) 2 ・・・(3) (Two R3's are hydrogen and boron hydride (BH 4 ) is one of the following.

2. The polycyclic aromatic hydrocarbon includes an acene. The magnesium battery electrolyte according to claim 1.

3. The solvent contains an ether compound having an ether bond (—O—). The magnesium battery electrolyte according to claim 1 or 2.

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

5. a positive electrode, a negative electrode, and a magnesium battery electrolyte; The magnesium battery electrolyte solution includes 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. Magnesium battery. Mg[B(OC(R1) 3 ) 4 ] 2 ・・・(1) (Each of the 24 R1's is either hydrogen (H), fluorine (F), an alkyl group, or a fluorinated alkyl group, provided that at least one of the 24 R1's is either fluorine or a fluorinated alkyl group.) Mg[(N(Si(R2) 3 ) 2 ] 2 ・・・(2) (Each of the 12 R2 is either hydrogen or an alkyl group.) Mg(R3) 2 ・・・(3) (Two R3's are hydrogen and boron hydride (BH 4 ) is one of the following.

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