JP2012221670A - Magnesium secondary battery and battery system including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnesium secondary battery having high energy density.SOLUTION: In a secondary battery using magnesium as a carrier, a compound of transition metal and fluorine, specifically a compound represented as a compositional formula: MgM1M2FX(M1 represents at least one or more transition metals selected from among Fe, Mn, Co, Ni, Cr, Cu, Mo, W, Pt, Hf, Os, Ir, Au, Hg, Tl, Pb and Sn, and M2 represents at least one selected from transition metal other than the M1 and Al while 0≤x≤1 is satisfied. X represents at least one halogen selected from among Cl, Br and I while 0≤z<0.5 is satisfied) is used as a positive electrode active material.

Description

  The present invention relates to a magnesium secondary battery and a battery system using the same.

With the miniaturization of personal computers, video cameras, mobile phones, etc., in the fields of information-related equipment and communication equipment, lithium secondary batteries have been put into practical use and have become widespread as power sources used for these equipment. Generally, a lithium secondary battery includes a positive electrode using a lithium transition metal oxide such as LiCoO ₂ as a positive electrode active material, a negative electrode using metal lithium, a carbon material, or the like as a negative electrode active material, and a lithium salt as a supporting salt. In an organic solvent. Lithium desorbed from the positive electrode is occluded in the negative electrode during charging, and conversely, lithium desorbed from the negative electrode is occluded in the positive electrode during discharge. That is, it is a rocking chair type secondary battery using lithium as a carrier. In lithium secondary batteries, metallic lithium or carbon material used as the negative electrode active material has a low reaction potential with lithium, and a non-aqueous electrolyte is used as the electrolyte. It has the advantage of density, and its use is rapidly expanding as a power source for small portable devices.

  In addition, large-sized lithium secondary batteries are being put into practical use for electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, or power storage power storage systems.

  However, lithium is extremely active, and there is a danger that it reacts with moisture in the air and burns. This requires sufficient consideration such as a dry environment without moisture in the manufacturing process of the lithium secondary battery, which leads to an increase in manufacturing cost. Also, in lithium secondary batteries, when lithium metal is used for the negative electrode, the dendrite (needle crystals) precipitates during the charge / discharge reaction, causing the dendrite to penetrate the separator, causing a short circuit, and the solvent burns. There is a case. Therefore, a new type of rocking chair type secondary battery in which a carrier material is changed is desired.

  Furthermore, lithium is mined as a lithium compound from salt lakes and the like, and it has been reported that it has a reserve of more than 100 years even if electric vehicles and the like are widely used. In order to disseminate secondary batteries for large-capacity power supply applications in the future, it is a precondition that it is possible to secure the battery materials necessary for mass dissemination in consideration of the amount of materials used in the batteries. It becomes.

  In view of the above situation, it is desirable to select a material that is chemically relatively stable, has a large amount of raw material supply, and has low price variability. Accordingly, attention is being focused on magnesium, which has abundant resources, and the development of a storage battery that uses it as a material for a secondary battery, that is, a magnesium secondary battery, is gradually attracting attention both at home and abroad.

  Thus, the development of magnesium secondary batteries is gradually progressing at home and abroad, aiming at high safety and low price. Magnesium is cheaper than lithium, has a material price of about 2/3 that of lithium, and has a high electric capacity density (2.21 Ah / kg). However, sufficient performance is not obtained with the current magnesium secondary battery. Therefore, research and development are underway to reduce the battery cost per capacity by bringing the performance closer to that of a lithium secondary battery.

The positive electrode is the key to improving the performance. In Patent Literature 1, MgMn ₂ O ₄ is studied as a positive electrode material for Mg secondary batteries. In Patent Document 2, a magnesium composite oxide represented by the composition formula Mg _x M1 _1-y M2 _y O ₂ .nH ₂ O and having a layered structure in the crystal structure is found as a positive electrode material for Mg secondary batteries. ing. In Patent Document 3, an oxide represented by the general formula MO or a sulfide represented by MS is presented as a positive electrode material for an Mg secondary battery (where M represents a metal element). In Patent Document 4, an oxide having a rutile structure, mainly TiO _2, has been proposed as a positive electrode material for an Mg secondary battery. In Patent Literature 5, an oxide positive electrode material containing Mo having an oxidation number of 6 is studied as a positive electrode material for an Mg secondary battery. In Patent Document 6, a manganese oxide obtained by heat-treating a precipitate generated by a reaction between a permanganate and hydrochloric acid has been found as a positive electrode material for an Mg secondary battery. Patent Document 7 is an invention relating to a halogen compound positive electrode material, mainly a chlorine compound positive electrode material.

JP 2001-76721 A JP 2002-255555 A JP 2005-228589 A JP 2006-505109 A JP 2007-280627 A JP 2009-64731 A JP 2007-157416 A

  However, as shown in Patent Document 7, for example, although the discharge capacity density is high, a sufficient energy density is not obtained because the operating potential is low. Therefore, an object of the present invention is to provide a magnesium secondary battery having a high energy density and a battery system using the same.

A magnesium secondary battery includes a positive electrode that reversibly absorbs and releases magnesium, a negative electrode that is disposed opposite to the positive electrode via a separator, and that reversibly stores and releases magnesium, and an electrolyte solution containing a magnesium compound. Is provided. As a result of searching for a secondary battery using magnesium as a carrier instead of lithium, the present inventor has reached the use of a transition metal fluorine compound as a positive electrode active material. Specifically, as the positive electrode active material, the composition formula _{MgxM1 1-y M2 y F 3} -z X z (M1 is Fe, Mn, Co, Ni, Cr, Cu, Mo, W, Pt, Hf, Os, Ir , Au, Hg, Tl, Pb, Sn, a transition metal selected from at least one or more, M2 is a transition metal other than M1 or at least one selected from Al: 0 ≦ x ≦ 1, X is Cl, The use of a transition metal and fluorine compound represented by at least one selected from Br, I halogen elements: 0 ≦ z <0.5).

  ADVANTAGE OF THE INVENTION According to this invention, a high energy density magnesium secondary battery and a battery system using the same can be provided. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

A unit cell model diagram of CaTiO ₃ having a perovskite structure. A unit cell model diagram of FeF ₃ having a perovskite structure. It is a figure which shows the cross-section of a magnesium secondary battery. It is a figure which shows the example of the battery system to which a magnesium secondary battery is applied.

  As a result of diligent research and repeated experiments, the present inventor obtained knowledge that some transition metal and fluorine compounds can reversibly store and release magnesium, and can be a positive electrode active material that operates at a high potential. It was. The present invention is based on this finding, and a positive electrode active material capable of forming a new concept rocking chair type secondary battery using magnesium as a carrier, and a magnesium secondary material formed using this positive electrode active material. Provide the next battery.

  A transition metal and fluorine compound was selected as the positive electrode active material. By using a transition metal fluorine compound, a high-potential magnesium secondary battery positive electrode can be obtained. Further, by using this positive electrode, a magnesium secondary battery having a high voltage and a high energy density can be obtained. A high voltage and high energy density magnesium secondary battery can be mounted on a product in which the above lithium secondary battery is used.

The positive electrode active material is a compound containing at least a transition metal and fluorine. A compound represented by a composition formula of MF ₃ (M is one or a plurality of transition metal compounds), occludes magnesium at a cation site present around, and has a perovskite structure (RMO ₃ : R is magnesium or an empty cation site) Can be.

The elements that enter the site of the central metal M of MF ₃ are transition metals Fe, Mn, Co, Ni, which have a function of taking an oxidation number of 1 to 3 when magnesium ions are occluded / released and maintaining electrical balance. It is selected from Cr, Cu, Mo, W, Pt, Hf, Os, Ir, Au, Hg, Tl, Pb, and Sn. M may be a single type or two or more types. A part of the site of F may be substituted with a halogen element X (Cl, Br, I) other than F. Therefore, it is expressed by Mg _x M1 _1-y M2 _y F _{3-z Xz} (x ≧ 0, y ≧ 0, z ≧ 0).

The compound of transition metal and fluorine used for the positive electrode active material is selected from at least one of the composition formula Mg _x M1 _1-y M2 _y F ₃ (M1 is Fe, Mn, Co, Ni) by occlusion of magnesium. M2 is a transition metal other than M1 and at least one selected from Al: 0 ≦ x ≦ 1), and the crystal structure has a perovskite structure.

Transition metal fluorine compounds have a perovskite structure as the crystal structure (FIGS. 1 and 2).
The perovskite structure is a crystal structure similar to perovskite expressed by the composition formula CaTiO ₃ . FIG. 1 shows a model diagram of a unit cell of CaTiO ₃ crystal. CaTiO ₃ having a perovskite structure is a crystal structure having a cubic unit cell. In this crystal structure, Ti is arranged in the body of the unit cell, O is arranged in the face center, and Ca is arranged in the vertex.

  The perovskite structure of the transition metal fluorine compound is a crystal structure belonging to a cubic system, in which the transition metal M1 (including the case where M1 is replaced by M2) is included in the body center of the unit cell, and F (F is another halogen) in the face center. It has a structure of Mg at the apex (when the number of Mg atoms is less than the number of cation sites at the apex, it becomes an empty cation site). The unit lattices have a stabilized structure due to the arrangement sharing the F of each face center, but have some distortion. When only the number of cation sites is considered in the unit cell, the maximum number of Mg entering the cation sites is 1. However, considering the electrical balance and the fact that magnesium ions are divalent, in M1 where the oxidation number changes between 2 and 3, the magnesium entering the cation site is halved and the oxidation number is 1 In M1, which changes between 1 and 3, the maximum number of magnesium entering the cation site is 1.

A unit cell model of the crystal structure of FeF ₃ in the case of the simplest composition condition (x = y = z = 0) and M1 = Fe in a compound of transition metal and fluorine (Mg _x M1 _{1 -y} M2 _y F ₃ ) As shown in FIG. FeF ₃ has one empty cation site that can occlude cations in the unit cell. A part of the site where Fe ions should exist may be missing and there may be an empty site. If it does in this way, the hole formed in the positive electrode active material will increase electrical conductivity, and is suitable for high capacity | capacitance.

  In addition, the presence of vacant sites makes it easier for magnesium ions to diffuse into the cathode crystal via the vacant sites, which is effective for increasing the capacity. In other words, empty cation sites exist at the initial stage of charging when the Mg ion density inside the positive electrode is high, so that the solid phase diffusion resistance of Mg ions hardly increases even in a low charge region, and the actually usable charge / discharge region is widened. You can also get the benefits.

The above-mentioned effect becomes remarkable when compared with the case where FeF ₃ is used for the lithium secondary battery.
When FeF ₃ is used as the positive electrode active material of the lithium secondary battery, the positive electrode composition when the maximum amount of lithium ions is occluded is LiFeF ₃ . At this time, since empty sites are occupied by lithium ions, it is theoretically impossible to store more lithium ions. Further, at the end of the discharge, the lithium ion occupancy increases, and there are fewer empty sites, which increases the diffusion resistance of lithium ions. On the other hand, in the case of a magnesium secondary battery, the diffusion of magnesium ions is continued until the positive electrode composition when Mg ions occupy all vacant sites is MgFeF ₃ and the discharge capacity is twice that of the lithium secondary battery. Resistance doesn't matter.

  As shown in FIG. 2, the square existing at the apex of the unit cell corresponds to the occupied site of Ca ions, becomes an empty site in the charged state, and is occupied by magnesium ions in the discharged state. Fe existing in the body center of the unit cell corresponds to Ti, and F existing in the surface center of the unit cell has a substituted crystal structure corresponding to the circle. Metal ions are oxidized during charging and conversely reduced during discharging, so that electrical neutrality with magnesium ions in the crystal lattice is maintained. In a transition metal and fluorine compound having such a crystal structure, the magnesium atom can move using each side of the cubic unit cell as a diffusion path in the solid phase, and magnesium ions are occluded at the apex site of the unit cell. A reversible reaction in which magnesium atoms present at the apex sites of the unit cell are eliminated as ions can be easily realized. Therefore, the compound of transition metal and fluorine is a good positive electrode active material capable of constituting a rocking chair type secondary battery using magnesium as a carrier.

Thus, compounds of transition metals and fluorine, the represented (M1 in its composition _{Mg x M1 1-y M2 y} F 3-z X z Fe, Mn, Co, Ni, Cr, Cu, Mo, W, Any one or a plurality of transition metals of Pt, Hf, Os, Ir, Au, Hg, Tl, Pb, and Sn, and M2 is the transition metal excluding M1 and not M1, and any of Al or Plural, 0 ≦ x <1, X is at least one selected from the halogen elements Cl, Br, and I, and 0 ≦ z <0.5.

  It is desirable that M1 be Fe because it has a large amount of resources and is inexpensive and has an advantage that the atomic weight is small and the weight energy density can be increased. M2 that replaces a part of the site of the central metal M1 can be a transition metal other than M1 or at least one of Al. M2 functions to stabilize the crystal structure of the transition metal and fluorine compound. Specifically, Al, Ti, Sc and the like are preferable. Moreover, since Al has the advantage of being trivalent and having a large amount of resources and being inexpensive, M2 is preferably Al.

  In addition, since the electronegativity of fluorine is 3.98 and the electronegativity of oxygen is 3.44, fluorine has a greater electronegativity than oxygen and other halogen elements, and the electrical inside of the lattice is Polarity increases. Fluorine has a smaller atomic radius and ionic radius and a smaller unit cell than other halogen elements. Therefore, a fluorine compound-based material tends to be a positive electrode material having a higher potential and an excellent volume energy density than an oxide-based material. Therefore, a high voltage and high capacity magnesium secondary battery can be obtained by using a fluorine compound-based positive electrode material.

  The halogen element X has a function of facilitating the insertion / extraction of magnesium ions by substituting a part of the F site and expanding the cation site in the crystal structure of the transition metal / fluorine compound. X is at least one selected from halogen elements other than F, and specific examples include Cl, Br, and I. X is preferably Cl. Since Cl has the highest electronegativity after F in halogen elements, it can suppress a decrease in polarity in the crystal. In addition, since the ionic radius is close to F as compared with other halogen elements, destabilization of the crystal structure due to strain can be suppressed.

Specific examples of the compound represented by the composition formula _{Mg x M1 1-y M2 y} F 3-z X z is, NiF ₃ to x = y = FeF ₃ to the z = 0 in M1 and Fe, Ni, Co there is CrF ₃ or the like to MnF _3, Cr to CoF _3, Mn to. Examples of the positive electrode active material to other, Mg to _{Mg x CuF 3-z X z} , Mg and _{Mo x MoF 3-z X z} , Mg x WF 3-z X z to W, Pt to Cu Mg _x auf _{where x PtF 3-z X z,} Mg x HfF 3-z X z to _{Hf, Mg x OsF 3-z} X z to _{Os, Mg x IrF 3-z} X z to Ir, and Au to _{3-z X z, Mg x} HgF 3-z X z, Mg x TlF 3-z X z to Tl, Mg and Pb _x PbF _{3-z X z} to Hg, Mg and Sn _x SnF _{3- z} X _z, Mg and Cl an _{X x M1 1-y M2 y} F 3-z Cl z, Mg and _{Br x M1 1-y M2 y} F 3-z Br z, Mg x M1 to I _{1- y M2 y F 3-z I} z and the like.

  In addition, since lithium secondary batteries use highly active lithium ions as carriers, magnesium secondary batteries use magnesium ions as carriers, so a dry environment without moisture is required in the manufacturing process of secondary batteries. do not do. Therefore, the secondary battery is excellent in terms of manufacturing cost and safety in manufacturing.

  In lithium secondary batteries, when lithium metal is used for the negative electrode, short-circuiting due to dendrite precipitation associated with charge / discharge is likely to occur, and thus negative electrodes made of carbon-based materials have been put into practical use. Therefore, lithium ions that are carriers do not originally exist on the negative electrode side, and positive electrode active materials that contain lithium ions are often used. In the magnesium secondary battery, even if magnesium metal is used for the negative electrode, since there is no dendrite precipitation due to charge / discharge, magnesium metal, magnesium alloy, or the like can be used for the negative electrode.

  When the magnesium secondary battery employs magnesium metal or a magnesium alloy as the negative electrode active material, the negative electrode and the battery container are integrated, that is, at least a part of the battery container is formed of metal magnesium or a magnesium alloy that serves as the negative electrode active material. It can also be implemented in such a manner that the portion of the battery case also serves as the negative electrode. Even when the battery case is made of metal magnesium or the like, the metal magnesium or the like is almost inert in the air, so that it is excellent in handleability and safety. Therefore, the magnesium secondary battery in which the battery case also serves as the negative electrode is a magnesium secondary battery in which the weight of the battery is reduced and the energy density, the output density, etc. are excellent as compared with the lithium secondary battery. In a lithium secondary battery, metallic lithium and the like are extremely active in air, particularly in air containing moisture, and thus such a battery case cannot serve as a negative electrode.

In addition, when the negative electrode is deactivated, supplementary charging (refreshing) can be performed using magnesium contained in the can. Furthermore, since a large amount of magnesium ions as carriers are present in the negative electrode, a positive electrode material that does not include cations as carriers, such as FeF ₃ , can be selected.

  The electrolytic solution is a liquid containing magnesium as a carrier in an ionic state, and is obtained by dissolving a magnesium salt as an electrolyte in a solvent. A battery can be constituted by any of a non-aqueous electrolyte using an organic solvent and an aqueous electrolyte using water as a solvent.

  As the electrolytic solution of the magnesium secondary battery, it is preferable to use an aqueous electrolytic solution in which a magnesium salt is dissolved in water as an electrolyte. Since no organic solvent is used, there is a merit in that there is no possibility of the solvent burning.

Another advantage of using a non-aqueous electrolyte is that the magnesium secondary battery can achieve a battery voltage exceeding the decomposition potential of water, resulting in a magnesium secondary battery with high output density.
In addition, in the case of a magnesium secondary battery using metallic lithium for the negative electrode, the one using an aqueous electrolyte solution can be charged / discharged between about 1.1 V and about 1.6 V, whereas it is non-aqueous. In the case of using an electrolytic solution, charging / discharging is possible between about 1.1 V and about 3.0 V.

In the case of an aqueous electrolyte, Mg (OH) ₂ , MgCl ₂ , Mg (NO ₃ ) _2, etc. can be used as the magnesium salt that can be used as the electrolyte. In the negative electrode using magnesium metal or magnesium alloy as the negative electrode active material, there is an advantage that deterioration (oxidation) of the negative electrode can be prevented. Therefore, it is more preferable to use Mg (OH) ₂ among the above electrolytes. In the case of an aqueous electrolyte, the electrolyte concentration is preferably a saturated concentration or a concentration close to that because the conductivity of the electrolyte can be increased.

In the case of a non-aqueous electrolyte, the magnesium salt used as the electrolyte includes Mg (BF ₄ ) ₂ , Mg (PF ₆ ) ₂ , Mg (ClO ₄ ) ₂ , Mg (CF ₃ SO ₃ ) ₂ , Mg (AsF ₆ ) ₂ etc. can be used.
An aprotic organic solvent can be used as the organic solvent. For example, a mixed solvent composed of one or more of cyclic carbonate, chain carbonate, cyclic ester, cyclic ether, chain ether and the like can be used. Examples of cyclic carbonates are ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, etc., examples of chain carbonates are dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, etc., examples of cyclic esters are gamma butyrolactone, gamma valero. Examples of lactones include tetrahydrofuran, 2-methyltetrahydrofuran and the like as examples of cyclic ethers, and examples of chain ethers include dimethoxyethane and ethylene glycol dimethyl ether. Any one of these can be used alone, or two or more can be mixed and used. The electrolyte concentration in the non-aqueous electrolyte is preferably 0.8 to 1.5 M (molar concentration of electrolyte present in 1 liter of electrolyte). When the concentration is low, the conductivity is lowered, and when the concentration is high, the viscosity becomes too high and the low-temperature characteristics are deteriorated. You may add flame retardants, such as phosphate ester and phosphite, to these electrolyte solutions.

  When a transition metal and fluorine compound is used as the positive electrode active material, Mg that has been occluded at a given cation site by charging moves through the solid phase via an adjacent cation site that is not filled with other Mg. Then, magnesium ions are desorbed from the crystal ends to the outside of the crystal. Further, at the time of discharge, magnesium ions are inserted from the crystal end, move in the Mg layer, and are occluded at a predetermined cation site.

  Next, the structure of the magnesium secondary battery using the positive electrode active material will be described. A magnesium secondary battery is a rocking chair type secondary battery that has a positive electrode, negative electrode, and electrolyte, and uses magnesium as a carrier. Electric energy can be stored and used by occluding and releasing ions into and from the electrode in the electrolyte. And

  A magnesium secondary battery is manufactured by forming an electrode group in which a positive electrode and a negative electrode are opposed to each other, and inserting this electrode body together with an electrolyte into a battery case. A separator is inserted between the positive electrode and the negative electrode to maintain electrical insulation.

  The shape and size of the magnesium secondary battery are not limited, and various types such as a cylindrical type, a stacked type, a coin type, and a card type can be used. An appropriate battery case may be adopted according to the shape of the battery to be manufactured. The battery case may be provided with a positive external terminal and a negative external terminal, or a part of the battery case may serve as a positive external terminal and a negative external terminal. Regardless of the shape, type, etc., the electrode body is housed in a battery case, electrically connected from the positive electrode and the negative electrode to the positive external terminal and the negative external terminal, respectively, The magnesium secondary battery is completed by injecting and sealing the battery case to isolate the battery system from the outside.

  FIG. 3 is a diagram schematically showing an example of the internal structure of the magnesium secondary battery 301. An electrode group including a positive electrode 307, a negative electrode 308, and a separator 309 inserted between the two electrodes is housed in a sealed state in the battery container 302. The structure of the electrode group can be various shapes such as a stack of strip-shaped electrodes shown in FIG. 3 or a wound shape in an arbitrary shape such as a cylindrical shape or a flat shape. As the shape of the battery container, a cylindrical shape, a flat oval shape, a rectangular shape, or the like may be selected according to the shape of the electrode group. A lid 303 is provided at the top of the battery container 302, and the lid 303 has a positive external terminal 304, a negative external terminal 305, and a liquid inlet 306. After the electrode group was stored in the battery container 302, the lid 303 was put on the opening of the battery container 302, and the outer periphery of the lid 303 was welded to be integrated with the battery container 302. For attachment of the lid 303 to the battery container 302, other methods such as caulking and bonding can be employed in addition to welding.

  The material of the battery container 302 is selected from materials that are corrosion resistant to the nonaqueous electrolyte, such as aluminum, stainless steel, and nickel-plated steel. In addition, when the battery container 302 is electrically connected to the positive electrode lead wire 310 or the negative electrode lead wire 311, the material is changed due to corrosion of the battery container or alloying with magnesium ions in the portion in contact with the electrolyte. Select the lead wire material so that there is no such thing.

In most cases, the compound of the transition metal and fluorine used as the positive electrode active material has a high electric resistance, so that it is used in combination with a conductive material in order to supplement their electrical conductivity. The conductive material is for ensuring the electrical conductivity of the positive electrode, and a carbon material having a high specific surface area, such as carbon black, activated carbon, acetylene black, or a mixture of two or more of graphite can be used. . Also, conductive fibers such as vapor-grown carbon or carbon (manufactured by carbonization at high temperature from pitch (by-products such as petroleum, coal, coal tar)) and carbon fiber produced from acrylic fiber (Polyacrylonitrile) It can be used as a conductive material. It is preferable to use a carbon material having a high specific surface area together with the carbon fiber. The carbon material having a high specific surface area assists the conductivity between the positive electrode active material and the conductive fiber, and the conductivity is further improved as compared with the case of using only the conductive fiber. It is also possible to use a metal material that is not oxidized and dissolved in the charge / discharge range of the positive electrode and has a lower electrical resistance than the positive electrode active material. For example, transitions made of corrosion resistant metals such as titanium and gold, carbides such as SiC and WC, and nitrides such as Si ₃ N ₄ and BN are exemplified. As manufacturing methods of these conductive materials, existing manufacturing methods such as a melting method and a chemical vapor deposition method can be used. When the charge / discharge current on the positive electrode is small and the electrical resistance of the positive electrode active material does not affect the battery performance, the use of a conductive material can be omitted.

  Examples of the binder for holding the positive electrode active material and the conductive material on the surface of the current collector foil include known materials such as a fluorine-based binder and a rubber-based binder, such as Teflon (registered trademark), polytetrafluoroethylene, and polyvinylidene fluoride. (PVDF), fluorine-containing resins such as fluorine rubber, and thermoplastic resins such as polypropylene and polyethylene can be used. A thermosetting resin such as a polyimide resin may be used for the binder. You may add the additive (for example, carboxymethylcellulose) for adjusting a dispersibility and a viscosity as needed.

  The positive electrode current collector is not limited by the material, shape, manufacturing method, or the like, and is preferably an electrochemically stable material, and any current collector can be used. For the positive electrode current collector, an aluminum foil having a thickness of 10 to 100 μm, an aluminum perforated foil having a thickness of 10 to 100 μm and a hole diameter of 0.1 to 10 mm, an expanded metal, a foam metal plate, or the like is used. As the material of the positive electrode current collector, stainless steel, titanium, or the like can be used in addition to aluminum. For the transition metal and fluorine compound, any current collector can be used without being limited by the material, shape, manufacturing method, and the like.

  The positive electrode 307 is prepared by mixing a conductive material and a binder with a powder of a positive electrode active material to prepare a paste-like positive electrode mixture. For example, the positive electrode mixture is applied to the surface of a metal foil current collector. Can be formed. The positive electrode mixture can be adjusted by adding a solvent for the purpose of adjusting the viscosity, etc. for the convenience of coating, and in that case, an organic solvent such as N-methyl-2-pyrrolidone should be used. Can do. For the production of the positive electrode, a known production method such as a doctor blade method, a dipping method, or a spray method can be employed, and the means is not limited. Moreover, after making a positive electrode slurry adhere to a collector, the organic solvent is dried, and a positive electrode can be produced by pressure forming the positive electrode by a roll press. In addition, a plurality of mixture layers can be laminated on the current collector by performing a plurality of times from application to drying.

  The positive electrode formed by coating the metal foil current collector is a sheet-like one, but this sheet-like positive electrode can have various thicknesses depending on the shape of the battery to be produced. Also, it can be of various sizes by means such as cutting. Moreover, what was pressurized by means, such as a press, in order to raise the density of a positive electrode mixture as needed may be used. At this time, the particle diameter of the positive electrode active material is defined to be equal to or less than the thickness of the mixture layer. When there are coarse particles having a size larger than the thickness of the mixture layer in the positive electrode active material powder, the coarse particles are removed in advance by sieving classification, wind classification or the like to produce particles having a thickness of the mixture layer or less.

  The negative electrode 308 is provided to face the positive electrode. The negative electrode active material may be any material as long as it can reversibly occlude / release (or dissolve / precipitate) magnesium, and its reaction potential is lower than the reaction potential of the transition metal and fluorine compound serving as the positive electrode active material. There are aluminum, zinc, lithium, silicon, tin and the like alloyed with magnesium, and there are also carbonaceous materials made of graphite and amorphous carbon capable of electrochemically occluding and releasing magnesium ions.

  Examples of the substance having a sufficiently low reaction potential and sufficient reversible storage / release (or dissolution / precipitation) ability include metal magnesium and magnesium alloy, and these are preferably used. Specifically, as the magnesium alloy, an Mg—Al alloy, an Mg—Zn alloy, an Mg—Mn alloy, or the like can be used. When metal magnesium or a magnesium alloy is used as the negative electrode active material, for example, a material such as metal magnesium can be formed into a foil shape or a plate shape to form a negative electrode, and the battery can be configured to face the positive electrode.

  When a negative electrode active material other than magnesium metal or magnesium alloy is used, a carbon material having a graphene structure or the like can be used. It may be a mixed negative electrode of materials such as graphite, graphitizable carbon, non-graphitizable carbon, a mixed negative electrode of a carbon material and a metal or an alloy, or a composite negative electrode. As carbon materials, natural graphite, artificial graphite, mesophase carbon, expanded graphite, carbon fiber, vapor grown carbon fiber, pitch-based carbonaceous material, needle coke, which can electrochemically occlude and release magnesium ions, Carbonaceous materials such as petroleum coke, polyacrylonitrile-based carbon fiber, carbon black, or amorphous carbon materials synthesized by thermal decomposition of 5-membered or 6-membered cyclic hydrocarbons or cyclic oxygen-containing organic compounds, etc. Is available.

Since the negative electrode active material generally used is a powder, the negative electrode 308 includes a negative electrode active material, a binder, and a current collector. A binder is mixed with the negative electrode active material to bond the powders together, and at the same time, adhere to the current collector. When high rate charge / discharge is required, a conductive agent may be added to the negative electrode.
The conductive agent does not participate in the occlusion / release of magnesium ions and acts as an electron medium, and therefore does not affect the occlusion / release reaction of magnesium ions in the negative electrode active material. A conductive polymer material made of polyacene, polyparaphenylene, polyaniline, or polyacetylene can also be used for the negative electrode.

  Any current collector can be used in the magnesium secondary battery without being limited by the material, shape, manufacturing method, and the like. Specifically, a copper foil having a thickness of 10 to 100 μm, a copper perforated foil having a thickness of 10 to 100 μm and a hole diameter of 0.1 to 10 mm, an expanded metal, a foam metal plate, etc. are used. Stainless steel, titanium, nickel, etc. are also applicable.

A negative electrode slurry in which a negative electrode active material, a binder, and an organic solvent are mixed is attached to a current collector by the doctor blade method, dipping method, spray method, etc., the organic solvent is dried, and the negative electrode is pressure-formed by a roll press. By doing so, a negative electrode can be produced.
Moreover, it is also possible to form a multilayer mixture layer on a current collector by carrying out a plurality of times from application to drying.

  It is desirable to make the particle size of the negative electrode active material not more than the thickness of the mixture layer. When there are coarse particles having a size larger than the thickness of the mixture layer in the negative electrode active material powder, the coarse particles are previously removed by sieving classification, wind classification or the like, and particles having a thickness of the mixture layer thickness or less are used.

  A separator 309 is inserted between the positive electrode 307 and the negative electrode 308 to prevent a short circuit between the positive electrode 307 and the negative electrode 308. The separator separates the positive electrode and the negative electrode and retains the electrolytic solution, and is a polyolefin polymer sheet made of polyethylene, polypropylene, or the like, or a fluorine polymer sheet typified by a polyolefin polymer and tetrafluoropolyethylene. It is possible to use a separator 309 or the like having a multilayer structure in which is welded. In the case of using a non-aqueous electrolyte, a thin microporous film such as polyethylene, polypropylene, cellulose, or polyimide, a nonwoven fabric, paper, or the like can be used. In the case of an aqueous electrolyte, a nonwoven fabric, paper, or the like can be used. A mixture of ceramics and a binder may be formed in a thin layer on the surface of the separator 309 so that the separator 309 does not contract when the battery temperature increases. Since these separators 309 need to allow magnesium ions to permeate during battery charging / discharging, they can generally be used for the magnesium secondary battery 301 if the pore diameter is 0.01 to 10 μm and the porosity is 20 to 90%. It is.

  The separator 309 is also inserted between the electrode disposed at the end of the electrode group and the battery container 302 so that the positive electrode 307 and the negative electrode 308 are not short-circuited through the battery container 302. An electrolyte solution composed of an electrolyte and a non-aqueous solvent is held on the surfaces of the separator 309, the positive electrode 307, and the negative electrode 308 and inside the pores.

  The upper part of the laminate is electrically connected to an external terminal via a lead wire. The positive electrode 307 is connected to the positive external terminal 304 via the positive lead wire 310. The negative electrode 308 is connected to the negative external terminal 305 via the negative lead wire 311. The positive lead wire 310 and the negative lead wire 311 can take any shape such as a wire shape, a foil shape, and a plate shape. Further, the material of the positive electrode lead wire 310 and the negative electrode lead wire 311 is arbitrary as long as the material can reduce the ohmic loss when a current is passed and the material does not react with the electrolytic solution. An insulating sealing material 312 is inserted between the positive electrode external terminal 304 or the negative electrode external terminal 305 and the battery container 302 so that both terminals are not short-circuited. The insulating seal material 312 can be selected from a fluororesin, a thermosetting resin, a glass hermetic seal, and the like, and any material that does not react with the electrolyte and has excellent airtightness can be used.

  A positive temperature coefficient (PTC) is provided in the middle of the positive electrode lead 310 or the negative electrode lead wire 311, or at the connection portion between the positive electrode lead wire 310 and the positive electrode external terminal 304, or at the connection portion between the negative electrode lead wire 311 and the negative electrode external terminal 305. ) When a current interruption mechanism using a resistance element is provided, when the temperature inside the battery becomes high, charging / discharging of the magnesium secondary battery 301 can be stopped to protect the battery.

  The magnesium secondary battery can be appropriately combined with other devices and systems. A battery system to which a magnesium secondary battery is applied includes an external device connected to the magnesium secondary battery and driven by electric power, and charge / discharge control means for controlling charge / discharge of the magnesium secondary battery. As an external device to be systemized in combination with a power generator, there is a drive device such as an electric motor. Other external devices include power devices such as electric motors, light emitting devices such as LEDs and light bulbs, heat generating devices such as heating wires, and electronic devices that operate by electricity.

  A system using a magnesium secondary battery can be used as an energy conversion device in combination with a power generation device such as a photovoltaic device. For example, the present invention can be applied to any renewable energy power generation system such as sunlight, geothermal heat, wave energy, and the like. For example, electric vehicles, plug-in hybrid vehicles, hybrid vehicles, transportation equipment, construction equipment, nursing care equipment, light vehicles, power tools, game machines, video machines, televisions, vacuum cleaners, robots, mobile terminal information equipment, submarine drive power supplies , Can be used as a power source for submarine searchers. Furthermore, the present invention can be applied to a solar power generation, wave power generation, geothermal power generation, a power storage system installed in a wind power plant, or a space station power source combined with solar power generation.

  Although the magnesium secondary battery using the transition metal and fluorine compound has been described above, it can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art, and specific constituent materials. , Shapes, parts, and the like may be changed, and a known technique may be appropriately added or replaced by a known technique. Hereinafter, further details will be described using examples. In Examples, a completely new type of rocking chair type secondary battery (magnesium secondary battery) was prepared using magnesium as a carrier, and the secondary battery was evaluated by a charge / discharge test. It should be noted that the type, composition, shape, etc. of the material can be changed without departing from the spirit of the present invention.

A magnesium secondary battery using FeF ₃ as a positive electrode active material as a compound of a transition metal having a perovskite structure and fluorine was produced. A positive electrode mixture was prepared by mixing 85 parts by weight of FeF ₃ with 12 parts by weight of acetylene black as a conductive material and 3 parts by weight of PVDF as a binder, and this positive electrode mixture was prepared as an aluminum foil current collector with a thickness of 20 μm. The sheet | seat with which the thickness of the positive mix was 50 micrometers on one side was produced by coating on both surfaces and press-molding. Next, this sheet was cut so that the area of the coated portion was 50 mm × 100 mm and the uncoated portion was 15 mm × 15 mm as a lead electrode to produce a positive electrode.

Metal magnesium was used for the negative electrode facing the positive electrode. Metal magnesium was cut so as to be 60 mm × 110 mm while leaving the lead electrode portion (15 mm × 15 mm), and a metal magnesium which sufficiently covered the coated portion of the positive electrode was produced. As a separator inserted between the positive electrode and the negative electrode, a nonwoven fabric having a thickness of 100 μm was used. As the electrolytic solution, a non-aqueous electrolytic solution in which acetonitrile as a solvent and Mg (ClO ₄ ) ₂ as an electrolyte was dissolved at a concentration of 1 mol / l was used.

  The above separator was inserted between the positive electrode and the negative electrode, and 11 negative electrodes and 10 positive electrodes were alternately stacked. After putting the laminated positive and negative electrodes and separator into the laminate cell and injecting the electrolyte, the lead electrode is provided so that the positive or negative electrode can be electrically connected from the outside of the laminate cell, and then the laminate cell is sealed. A laminated cell type magnesium secondary battery was completed.

A charge / discharge test was performed on the manufactured magnesium secondary battery of Example 1. In the charge / discharge test, charging is performed at a constant current of 0.3 mA / cm ² until a final charge voltage of 3.0 V, and then discharged at a constant current of 0.3 mA / cm ² until a final discharge voltage of 0.3 V. The charge / discharge cycle for performing the above was repeated. The results are shown in Table 1.

Example 2 is an example in which the negative electrode of the magnesium secondary battery of Example 1 was changed to a magnesium alloy. A magnesium alloy (Al: 6% by weight) was used for the negative electrode. The magnesium alloy was cut so that the lead electrode portion (15 mm × 15 mm) was left and became 60 mm × 110 mm, so that the coated portion of the positive electrode was sufficiently covered. Other structures of the positive electrode, separator, electrolyte, and battery using FeF ₃ were the same as in Example 1, and a magnesium secondary battery was produced by the same method.

  A charge / discharge test was conducted on the magnesium secondary battery of Example 1 as in Example 1.

Example 3 is an example in which the positive electrode of the magnesium secondary battery of Example 2 was changed to one using MnF ₃ . A positive electrode mixture was prepared by mixing 85 parts by weight of MnF ₃ with 12 parts by weight of acetylene black as a conductive material and 3 parts by weight of PVDF as a binder, and collecting the positive electrode mixture with an aluminum foil current collector having a thickness of 20 μm. The sheet is coated on both sides of the body and pressure-molded to produce a sheet having a positive electrode mixture thickness of 50 μm on one side. Then, the area of the coated part is 50 mm × 100 mm, and the sheet is not coated as a lead electrode. The portion was cut to 15 mm × 15 mm to produce an electrode.

  The negative electrode was manufactured in the same manner as in Example 2 using a magnesium alloy (Al: 6% by weight). Other separators, electrolytes, and battery structures were the same as those in Example 1, and a magnesium secondary battery was produced by the same method.

  The charge / discharge test was conducted on the magnesium secondary battery of Example 3 as in Example 1.

[Comparative Example 1]
As Comparative Example 1, a magnesium secondary battery using manganese oxide as the positive electrode active material was produced. The positive electrode was prepared by mixing 85 parts by weight of manganese oxide represented by the composition formula MnO ₂ with 12 parts by weight of acetylene black as a conductive material and 3 parts by weight of PVDF as a binder. The mixture is applied to both sides of an aluminum foil current collector having a thickness of 20 μm, and pressure-molded to produce a sheet in which the thickness of the positive electrode mixture is 50 μm on one side. Was cut to be 50 mm × 100 mm, and the uncoated portion as a lead electrode was 15 mm × 15 mm, to prepare an electrode.

  The negative electrode was manufactured in the same manner as in Example 2 using a magnesium alloy (Al: 6% by weight). Other separators, electrolytes, and battery structures were the same as those in Example 1, and a magnesium secondary battery was produced by the same method.

  A charge / discharge test was performed on the magnesium secondary battery of Comparative Example 1 as in Example 1.

[Comparative Example 2]
As Comparative Example 2, a magnesium secondary battery using molybdenum oxide as the positive electrode active material was produced. The positive electrode was prepared by mixing 85 parts by weight of molybdenum oxide represented by the composition formula MoO ₃ with 12 parts by weight of acetylene black as a conductive material and 3 parts by weight of PVDF as a binder. The mixture is applied to both sides of an aluminum foil current collector having a thickness of 20 μm, and pressure-molded to produce a sheet in which the thickness of the positive electrode mixture is 50 μm on one side. Was cut to be 50 mm × 100 mm, and the uncoated portion as a lead electrode was 15 mm × 15 mm, to prepare an electrode.

  The negative electrode was manufactured in the same manner as in Example 2 using a magnesium alloy (Al: 6% by weight). Other separators, electrolytes, and battery structures were the same as those in Example 1, and a magnesium secondary battery was produced by the same method.

  A charge / discharge test was performed on the magnesium secondary battery of Comparative Example 1 as in Example 1.

[Comparative Example 3]
As Comparative Example 3, a magnesium secondary battery using molybdenum sulfide as the positive electrode active material was produced. The positive electrode is prepared by mixing 85 parts by weight of molybdenum sulfide represented by the composition formula Mo ₆ S ₈ with 12 parts by weight of acetylene black as a conductive material and 3 parts by weight of PVDF as a binder. This positive electrode mixture is applied to both sides of an aluminum foil current collector having a thickness of 20 μm, and pressure-molded to produce a sheet in which the thickness of the positive electrode mixture is 50 μm on one side. The electrode was cut to have an area of 50 mm × 100 mm and an uncoated portion of 15 mm × 15 mm as a lead electrode.

  The negative electrode was manufactured in the same manner as in Example 2 using a magnesium alloy (Al: 6% by weight). Other separators, electrolytes, and battery structures were the same as those in Example 1, and a magnesium secondary battery was produced by the same method.

  A charge / discharge test was performed on the magnesium secondary battery of Comparative Example 1 as in Example 1.

  Table 1 shows the configurations of the magnesium secondary batteries produced in Examples 1 to 3 and Comparative Examples 1 to 3, and the results obtained in the charge / discharge test.

  As a result of the charge / discharge test, the types of positive and negative electrodes, open circuit voltage (OCV) and average operating voltage, theoretical capacity per weight, actual discharge capacity, and energy density were calculated.

When the positive electrode material was changed using a magnesium alloy as the negative electrode, in Examples 2 and 3 using the fluorine compound-based positive electrode material, the average operating voltage was compared with Comparative Examples 1 and 2 using the oxide-based positive electrode material. And the energy density of the positive electrode was high. From the above, it is clear that FeF ₃ having a perovskite structure and other fluorine compound-based positive electrode materials are very promising as a positive electrode material for magnesium secondary batteries.

When FeF ₃ was used for the positive electrode, there was almost no change in OCV when the metal magnesium negative electrode was used (Example 1) and when the magnesium alloy negative electrode was used (Example 2). However, in Example 2 using a magnesium alloy negative electrode, the average operating voltage and the discharge capacity were high, and the energy density of the positive electrode was as high as 400 mWh / g or more. Further, when Examples 2 and 3 were compared, the energy density of the positive electrode was higher than 400 mWh / g when FeF ₃ was used.

  Judging from the above results, it can be concluded that a secondary battery using a transition metal and fluorine compound as a positive electrode active material can constitute a secondary battery capable of reversibly charging and discharging a considerable capacity. Therefore, a positive electrode for a magnesium secondary battery having a high potential can be obtained, and a magnesium secondary battery having a high operating voltage and a high energy density can be obtained by using this positive electrode.

The positive electrode active material was FeF _2.8 Cl _0.2, and a material with expanded vacant sites where Mg ions were occluded was used for the positive electrode. The positive electrode active material had a capacity density of 190 mAh / g. 85 parts by weight of this positive electrode active material, 12 parts by weight and 3 parts by weight of acetylene black were mixed to prepare a positive electrode mixture, and this positive electrode mixture was applied to both sides of an aluminum foil current collector having a thickness of 20 μm. A sheet in which the thickness of the positive electrode mixture was 50 μm on one side was produced by pressure molding. Next, this sheet was cut so that the area of the coated portion was 250 mm × 100 mm, and the uncoated portion was 25 mm × 25 mm as a lead electrode to produce an electrode. The produced positive electrode was 20 sheets. The positive electrode weight was adjusted so that the capacity per electrode was 0.9 Ah.

  The negative electrode was made of a magnesium alloy (Al: 6% by weight), the area facing the positive electrode was 250 mm × 100 mm, the lead-out portion was 25 mm × 25 mm, and the thickness was 0.1 mm. 21 negative electrodes were prepared.

  An electrode group in which these positive electrodes and negative electrodes were alternately laminated was inserted into the rectangular battery container of FIG. 1 to produce a rectangular battery. The separator of Example 1 was inserted between the positive electrode and the negative electrode, and the electrolytic solution used in Example 1 was injected into the prismatic battery.

  The charge / discharge test was performed with a current of 3A and a charge / discharge voltage range of 1 to 3.5 V to obtain a charge / discharge capacity of 17 to 18 Ah.

  FIG. 4 shows a battery system in which two magnesium secondary batteries 401a and 401b are connected in series. Let this system be S1. Magnesium secondary batteries 401a and 401b are rectangular magnesium secondary batteries having the same specifications as in Example 4. Each of the magnesium secondary batteries 401a and 401b is an electrode having the same specifications including a positive electrode 407, a negative electrode 408, and a separator 409. A positive electrode external terminal 404 and a negative electrode external terminal 405 are provided on the top. In FIG. 4, the number of positive electrodes 407 and negative electrodes 408 is simplified to one each, but in actuality, it has a laminated structure of 20 positive electrodes and 21 negative electrodes.

  An insulating sealing material 412 is inserted between each external terminal and the battery lid 403 so that the external terminals are not short-circuited. The electrolyte is supplied from a liquid injection port 406 provided in the battery lid 403. 4, parts corresponding to the positive electrode lead wire 110 and the negative electrode lead wire 111 of FIG. 1 are omitted, but the internal structure of the magnesium secondary batteries 401a and 401b is the same as that of FIG. The capacity is 17 to 18 Ah under 6 hour rate discharge conditions.

  The negative external terminal 405 of the magnesium secondary battery 401 a is connected to the negative input terminal of the charge / discharge controller 416 by the power cable 413. The positive external terminal 404 of the magnesium secondary battery 401a is connected to the negative external terminal 405 of the magnesium secondary battery 401b via the power cable 414. The positive external terminal 404 of the magnesium secondary battery 401 b is connected to the positive input terminal of the charge / discharge controller 416 by the power cable 415. With such a wiring configuration, the two magnesium secondary batteries 401a and 401b can be charged or discharged. The number of batteries in series and the number in parallel can be arbitrarily changed according to the amount of power required for the system S1.

  The charge / discharge controller 416 controls charging / discharging of the magnesium secondary battery, and exchanges power with an external device (hereinafter referred to as an external device) 419 via the power cables 417 and 418. I do. The external device 419 includes various electric devices such as an external power source and a regenerative motor for supplying power to the charge / discharge controller 416, and an inverter, a converter, and a load that supply power from the system. An inverter or the like may be provided depending on the type of AC and DC that the external device supports. As these devices, known devices can be arbitrarily applied.

  In addition, a power generation device 422 simulating the operating conditions of the wind power generator was installed as a device that generates renewable energy, and connected to the charge / discharge controller 416 via the power cables 420 and 421. Renewable energy refers to an energy source that is derived from a natural phenomenon that is regenerated for a relatively short period of time, spontaneously or constantly, and that does not deplete for an extremely long period of time. In addition, natural energy such as sunlight, geothermal energy, and wave power can be cited. Therefore, in the case of using sunlight, the power generation device 422 can be replaced with a solar power generation device.

  When the power generation device 422 generates power, the charge / discharge controller 416 shifts to the charge mode, supplies power to the external device 419, and charges the magnesium secondary batteries 412a and 412b with surplus power. Further, when the power generation amount simulating the wind power generator is smaller than the required power of the external device 419, the charge / discharge controller 416 operates to discharge the magnesium secondary batteries 412a and 412b. The power generation device 422 can be replaced with another power generation device, that is, any device such as a solar cell, a geothermal power generation device, a fuel cell, a gas turbine generator, or the like. The charge / discharge controller 416 stores a program capable of automatic operation so as to perform the above-described operation.

  In this example, the magnesium secondary battery of Example 4 was used. The square battery shown in FIG. 1 may be manufactured using the positive electrode active material described in Examples 1 to 3, and may be replaced with the magnesium secondary batteries 401a and 401b shown in FIG. The charge / discharge conditions of these batteries depend on the types of materials such as the positive electrode active material and the negative electrode active material. The charging / discharging conditions are determined by the design of the material and usage of the magnesium secondary battery. After charging the magnesium secondary batteries 401a and 401b, the charge / discharge controller 416 is switched to the discharge mode to discharge each battery. Normally, the discharge is stopped when a certain lower limit voltage is reached.

  Using the system described above, the external device 419 supplies power during charging and consumes power during discharging. The external device 419 is an electric motor or the like. The process was performed up to 5 hour rate discharge, and a high capacity of 90% was obtained with respect to the capacity during 1 hour rate discharge. In addition, the power generation device 422 simulating a wind power generator was able to perform charging at a three-hour rate during power generation.

  The system of the present embodiment can be applied to equipment that uses an electric motor. Electric vehicles, hybrid electric vehicles, transportation equipment, construction equipment, nursing care equipment, light vehicles, power tools, game machines, video machines, televisions, vacuum cleaners, robots, portable terminal information devices, and the like.

  In addition, the system of the present embodiment can be used as a storage system installed in a solar power generation, wave power generation, geothermal power generation or wind power plant, or a power supply for a space station combined with solar power generation, an emergency power source. It can be used for purposes such as For example, emergency control of remote control equipment for social infrastructure systems that have functions to manage information in the infrastructure network and control its flow by performing remote control in infrastructure networks such as traffic, power, gas, water, and the Internet Can be used as a power source.

301, 401a, 401b Magnesium secondary battery 302, 402 Battery container 303, 403 Lid 304, 404 Positive external terminal 305, 405 Negative external terminal 306, 406 Injection port 307, 407 Positive electrode 308, 408 Negative electrode 309, 409 Separator 310 Positive electrode Lead wire 311 Negative electrode lead wires 312, 412 Insulating sealing material 413, 414, 415, 417, 418, 420, 421 Power cable 416 Charge / discharge controller 419 External device 422 Power generator

Claims (11)

A positive electrode that reversibly absorbs and releases magnesium;
A negative electrode disposed opposite to the positive electrode via a separator, and reversibly occluding and releasing magnesium;
A magnesium secondary battery comprising an electrolyte solution containing a magnesium compound,
The magnesium secondary battery, wherein the positive electrode uses a compound containing fluorine and a transition metal as a positive electrode active material. The magnesium secondary battery according to claim 1,
The positive electrode active material has a composition formula Mg _x M _{1 1 -y} M 2 _y F _{3 -z} X _z (M 1 is Fe, Mn, Co, Ni, Cr, Cu, Mo, W, Pt, Hf, Os, Ir, Au) , Hg, Tl, Pb, Sn, a transition metal selected from at least one or more, M2 is a transition metal other than M1 or at least one selected from Al: 0 ≦ x ≦ 1, X is Cl, Br, A magnesium secondary battery characterized by being a compound represented by at least one selected from halogen elements of I: 0 ≦ z <0.5). A magnesium secondary battery according to claim 1 or 2,
The magnesium secondary battery, wherein the positive electrode active material is FeF ₃ or MnF ₃ . A magnesium secondary battery according to any one of claims 1 to 3,
The magnesium negative battery, wherein the negative electrode uses metallic magnesium or an alloy containing magnesium as a negative electrode active material. The magnesium secondary battery according to claim 4,
A battery container containing the positive electrode, the negative electrode and the electrolyte;
A magnesium secondary battery, wherein at least a part of a battery container serves as the negative electrode active material. A magnesium secondary battery according to any one of claims 1 to 5,
A magnesium secondary battery, wherein the positive electrode active material has a perovskite structure. A magnesium secondary battery;
Charge / discharge control means for controlling charge / discharge of the magnesium secondary battery;
A battery system comprising an external device connected to the magnesium secondary battery, wherein the magnesium secondary battery is a magnesium secondary battery according to any one of claims 1 to 6. . The battery system according to claim 7, wherein
Equipped with a power generator,
A battery system, wherein the magnesium secondary battery is charged with electric power generated by the power generation device. The battery system according to claim 8, wherein
The battery system, wherein the power generation device is a photovoltaic device. The battery system according to any one of claims 7 to 9,
The battery system according to claim 1, wherein the external device is at least one of a power device, a light emitting device, a heat generating device, and an electronic device. The battery system according to any one of claims 7 to 10,
The battery system, wherein the external device includes means for generating electric energy.

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