WO2012105439A1

WO2012105439A1 - Electrode active material, electrode, and secondary battery

Info

Publication number: WO2012105439A1
Application number: PCT/JP2012/051781
Authority: WO
Inventors: 佐藤　正春; 尾上　智章; 英久目代; 鋤柄　宜
Original assignee: 株式会社村田製作所; 本田技研工業株式会社
Priority date: 2011-02-01
Filing date: 2012-01-27
Publication date: 2012-08-09
Also published as: JPWO2012105439A1

Abstract

An electrode active material having general formula (I) or (II) in the structural unit thereof. X is C, Si, or P; Y is a substituent group indicated by (III-1) or (III-2); Z is CH₂, CF₂, O, S, SO₂, Se, or N-R' (R' being a hydrogen atom, an alkyl group, an aryl group, or an oxygen radical); and R₁-R₇ are any substituent group. As a result, the electrode active material capable of recharging in a short time and having high energy density, high output, and good cycle characteristics with little decrease in capacity even after repeated discharge is achieved.

Description

Electrode active material, electrode, and secondary battery

The present invention relates to an electrode active material, an electrode, and a secondary battery, and more particularly to an electrode active material that repeatedly charges and discharges using a battery electrode reaction, an electrode using the electrode active material, and a secondary battery.

With the expansion of the market for portable electronic devices such as mobile phones, notebook computers and digital cameras, cordless power supplies for these electronic devices have a high energy density and high output, and long-life secondary batteries are expected.

In order to meet such demands, secondary batteries using an alkali metal ion such as lithium ion as a charge carrier and utilizing an electrochemical reaction accompanying the charge transfer have been developed. In particular, lithium ion secondary batteries have a high energy density and are becoming widespread as in-vehicle batteries.

By the way, of the constituent elements of the secondary battery, the electrode active material is a substance that directly contributes to the battery electrode reaction such as the charge reaction and the discharge reaction, and has the central role of the secondary battery. That is, the battery electrode reaction is a reaction that occurs with the transfer of electrons by applying a voltage to an electrode active material that is electrically connected to an electrode disposed in the electrolyte, and proceeds during charging and discharging of the battery. To do. Therefore, as described above, the electrode active material has a central role of the secondary battery in terms of system.

In the lithium ion secondary battery, a lithium-containing transition metal oxide is used as a positive electrode active material, a carbon material is used as a negative electrode active material, and an insertion reaction and a desorption reaction of lithium ions with respect to these electrode active materials are used. Charging / discharging.

However, the lithium ion secondary battery has a problem in that the speed of charging and discharging is limited because the movement of lithium ions in the positive electrode is rate limiting. That is, in the above-described lithium ion secondary battery, the migration rate of lithium ions in the transition metal oxide of the positive electrode is slower than that of the electrolyte and the negative electrode, and therefore the battery reaction rate at the positive electrode becomes the rate-determining rate. As a result, there is a limit to increasing the output and shortening the charging time.

Therefore, in order to solve these problems, research and development of secondary batteries using organic radical compounds, organic sulfur compounds, and quinone compounds as electrode active materials have been actively conducted in recent years.

For example, Patent Document 1 is known as a prior art document using an organic radical compound as an electrode active material.

Patent Document 1 discloses a secondary battery active material using a nitroxyl radical compound, an oxy radical compound, and a nitrogen radical compound having a radical on a nitrogen atom.

In organic radical compounds, the unpaired electrons that react are localized in the radical atoms, so that the concentration of the reaction site can be increased, and thus a high-capacity secondary battery can be realized. Further, since the reaction rate of radicals is high, it is considered that the charging time can be completed in a short time by performing charging / discharging utilizing a redox reaction of a stable radical.

And in this patent document 1, the Example using a highly stable nitroxyl radical as a radical is described, for example, the electrode layer containing a nitronyl nitroxide compound is used as a positive electrode, and lithium bonding copper foil is used as a negative electrode. When a secondary battery was produced and repeatedly charged and discharged, it was confirmed that charging and discharging were possible over 10 cycles.

Also, Patent Documents 2 and 3 are known as prior art documents using an organic sulfur compound as an electrode active material.

Patent Document 2 discloses a novel organic sulfur compound, which is a positive electrode material, has an SS bond in a charged state, and the SS bond is cleaved during discharge of the positive electrode to form an organic sulfur metal salt having a metal ion. Metal-sulfur battery cells have been proposed.

In this Patent Document 2, a disulfide organic compound represented by the general formula (1 ′) (hereinafter referred to as “disulfide compound”) is used as the organic sulfur compound.

RSSR (1 ')
Here, R represents an aliphatic organic group or an aromatic organic group, and each includes the same or different cases.

The disulfide compound can undergo a two-electron reaction, and the S—S bond is cleaved in a reduced state (discharge state), thereby forming an organic thiolate (RS—). This organic thiolate forms an S—S bond in the oxidized state (charged state) and is restored to the disulfide compound represented by the general formula (1 ′). In other words, since the disulfide compound forms an SS bond having a small binding energy, a reversible redox reaction occurs using the bond and cleavage by the reaction, and thus charge and discharge can be performed.

Patent Document 3 discloses the following formula (2 ′):
-(NH-CS-CS-NH) (2 ')
A battery electrode comprising rubeanic acid or a rubeanic acid polymer that has a structural unit represented by the formula (II) and can be bonded to lithium ions has been proposed.

The rubeanic acid or rubeanic acid polymer containing the dithione structure represented by the general formula (2 ′) binds to lithium ions during reduction, and releases the bound lithium ions during oxidation. Charging / discharging can be performed by utilizing such a reversible oxidation-reduction reaction of rubeanic acid or rubeanic acid polymer.

In Patent Document 3, when rubeanic acid is used as the positive electrode active material, a two-electron reaction is possible, and a secondary battery having a capacity density of 400 Ah / kg at room temperature is obtained.

Further, Patent Document 4 is known as a prior art document using a quinone compound as an electrode active material.

Patent Document 4 proposes an electrode active material containing a specific phenanthrenequinone compound having two quinone groups in the ortho-positional relationship.

The specific phenanthrenequinone compound described in Patent Document 4 can cause a two-electron reaction peculiar to the quinone compound between the mobile carrier and a reversible oxidation-reduction reaction. Furthermore, the specific phenanthrenequinone compound is oligomerized or polymerized to achieve insolubilization in an organic solvent without causing a decrease in the number of reaction electrons due to repulsion between electrons. Patent Document 4 shows that the phenanthrenequinone dimer exhibits two oxidation-reduction voltages (around 2.9 V and around 2.5 V), and the initial discharge capacity reaches 200 Ah / kg.

JP 2004-207249 A (paragraph numbers [0278] to [0282]) US Pat. No. 4,833,048 (Claim 1, column 5, line 20 to column 28) JP 2008-147015 A (Claim 1, paragraph number [0011], FIG. 3, FIG. 5) JP 2008-222559 A (Claim 4, paragraph numbers [0027] and [0033], FIGS. 1 and 3)

However, in Patent Document 1, although an organic radical compound such as a nitroxyl radical compound is used as an electrode active material, the charge / discharge reaction is limited to a one-electron reaction involving only one electron. That is, in the case of an organic radical compound, when a multi-electron reaction involving two or more electrons is caused, the radical lacks stability and decomposes, and the radical disappears and the reversibility of the charge / discharge reaction is lost. . For this reason, the organic radical compound as in Patent Document 1 must be limited to a one-electron reaction, and it is difficult to realize a multi-electron reaction that can be expected to have a high capacity.

In Patent Document 2, a low-molecular disulfide compound in which two electrons are involved is used. However, since it repeatedly binds and cleaves with other molecules along with the charge / discharge reaction, it lacks stability, and charge / discharge reaction is not performed. If it is repeated, the capacity may decrease.

In Patent Document 3, a rubeanic acid compound containing a dithione structure is used to cause a two-electron reaction. However, when a polymer compound such as a rubeanic acid polymer is used, an intermolecular interaction in the rubeanic acid polymer is performed. As a result of the large action and hindering the movement of ions, a sufficient reaction rate could not be obtained. For this reason, it took a long time to charge. In addition, since the movement of ions is hindered as described above, the proportion of active materials that can be effectively used is reduced, and thus it has been difficult to realize a secondary battery having a desired high output.

Patent Document 4 uses a phenanthrenequinone compound having two quinone groups in the ortho-positional position as an electrode active material, and thus is excellent in stability, but is synthesized because it is a condensed ring compound. Difficult and capacity density is small.

The present invention has been made in view of such circumstances, and can be charged in a short time, has a large energy density and high output, and an electrode active material having good cycle characteristics with little decrease in capacity even after repeated charge and discharge, It aims at providing the electrode and secondary battery which use this electrode active material.

The inventors of the present invention have made extensive studies to achieve the above object. As a result, an atomic group in which a sterically bulky substituent having a double bond is bonded to any element of C, Si, and P. The organic compound having a plurality of compounds can introduce a plurality of electrochemically active double bonds to increase the capacity density, and the intermolecular interaction is weakened by the steric bulk of the substituent. As a result, it was found that the movement of ions during the charge / discharge reaction was facilitated, the reaction proceeded smoothly, and charging in a short time or discharging at a high output became possible.

The present invention has been made based on such knowledge, the electrode active material according to the present invention is an electrode active material used as an active material of a secondary battery that repeats charge and discharge by a battery electrode reaction, The sterically bulky substituent Y is mainly composed of an organic compound containing a plurality of atomic groups X = Y bonded to a specific element X selected from C, Si, and P in a structural unit. And

In the electrode active material of the present invention, the substituent Y is

It is preferable that it is at least one selected from the group represented by.

In the formula, R ₁ to R ₃ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted cycloalkyl group, a substituted Or an unsubstituted alkoxyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted thioaryl group, Substituted or unsubstituted thioalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted formyl group, substituted or unsubstituted silyl group, substituted or unsubstituted boryl group, substituted or unsubstituted stannyl group, substituted Or unsubstituted cyano group, substituted or unsubstituted nitro group, substituted or unsubstituted Nitroso group, a substituted or unsubstituted amino group, a substituted or unsubstituted imino group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, and represents at least one kind of halogen atom, R ₁ ~ R ₃ includes the same case and includes a case where they are linked to each other to form a saturated or unsaturated ring.

Also, in the electrode active material of the present invention, the organic compound has the general formula

It is preferable to be represented by.

In the formula, R ₄ and R ₅ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted cycloalkyl group, a substituted Or an unsubstituted alkoxyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted thioaryl group, Substituted or unsubstituted thioalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted formyl group, substituted or unsubstituted silyl group, substituted or unsubstituted boryl group, substituted or unsubstituted stannyl group, substituted Or unsubstituted cyano group, substituted or unsubstituted nitro group, substituted or unsubstituted Nitroso group, a substituted or unsubstituted amino group, a substituted or unsubstituted imino group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, and represents at least one kind of halogen atom, R ₄ , R ₅ include the same case, and include the case where they are linked to each other to form a saturated or unsaturated ring.

Further, in the electrode active material of the present invention, at least one of R ₄ and R ₅ is N—R ′ (where R ′ is one or more of hydrogen atoms, alkyl groups, aryl groups, and oxygen radicals). At least one or a combination thereof is preferred.

It is preferable to be represented by.

Here, in the formula, R ₆ and R ₇ are a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted cycloalkyl group, a substituted Or an unsubstituted alkoxyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted thioaryl group, Substituted or unsubstituted thioalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted formyl group, substituted or unsubstituted silyl group, substituted or unsubstituted boryl group, substituted or unsubstituted stannyl group, substituted Or unsubstituted cyano group, substituted or unsubstituted nitro group, substituted or unsubstituted Nitroso group, a substituted or unsubstituted amino group, a substituted or unsubstituted imino group, shows a substituted or unsubstituted carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, and at least one kind of halogen atoms. R ₆ and R ₇ include the same case, and include the case where they are connected to each other to form a saturated or unsaturated ring. Z is selected from CH ₂ , CF ₂ , O, S, SO ₂ , Se, and N—R ′ (R ′ is selected from one or more hydrogen atoms, alkyl groups, aryl groups, and oxygen radicals) At least one kind or a combination thereof is shown.) At least one kind selected from the above or a combination thereof is shown.

In the electrode active material of the present invention, it is preferable that at least one of R ₆ and R ₇ contains the NR ′.

The electrode according to the present invention is characterized by containing any of the electrode active materials described above and a conductive material.

In the secondary battery according to the present invention, any one of the electrode active materials described above is included in at least one of a reaction starting material, a product, and an intermediate product in a discharge reaction of the battery electrode reaction. It is a feature.

Furthermore, the secondary battery according to the present invention has a positive electrode, a negative electrode, and an electrolyte, and the positive electrode contains any one of the electrode active materials described above.

According to the electrode active material of the present invention, the structural unit contains a plurality of atomic groups X = Y in which a sterically bulky substituent Y is bonded to a specific element X selected from C, Si, and P. Since the organic compound is mainly used, the bulk of the substituent Y weakens the intermolecular interaction between the atomic groups, and ions easily move during the charge / discharge reaction. Therefore, the charge / discharge reaction proceeds smoothly, and charging in a short time becomes possible. And since charging / discharging reaction advances smoothly in this way, the ratio of the electrode active material which can be utilized effectively increases, and discharge with high output is attained. In addition, since the organic compound has introduced a plurality of electrochemically active double bonds, it has high reactivity with cations such as lithium ions, has high charge / discharge efficiency, and high capacity density electrode activity. A substance can be obtained.

In addition, according to the electrode of the present invention, since it contains any of the electrode active materials and conductive materials described above, the charge / discharge efficiency is good, the battery can be charged in a short time, and the output is increased. Can be obtained.

Furthermore, according to the secondary battery of the present invention, any one of the electrode active materials described above is included in at least one of reaction starting materials, products, and intermediate products in the discharge reaction of the battery electrode reaction. High energy density, quick charge, discharge at high output, rechargeable battery with good cycle characteristics with little capacity degradation even after repeated charge and discharge, and long battery life with stable battery characteristics It becomes.

Moreover, since the electrode active material is mainly composed of organic compounds, it is possible to obtain a secondary battery with low environmental impact and safety.

It is sectional drawing which shows one Embodiment of the coin-type battery as a secondary battery which concerns on this invention.

Next, an embodiment of the present invention will be described in detail.

The electrode active material of the present invention is an organic compound containing a plurality of atomic groups X = Y in which a sterically bulky substituent Y is bonded to a specific element X selected from C, Si and P in a constituent unit Is the subject. As a result, it is possible to obtain a secondary battery having a large energy density, capable of being charged quickly, capable of discharging at a high output, having good cycle characteristics with little decrease in capacity even after repeated charge and discharge, and having stable battery characteristics. Is possible.

That is, the intermolecular interaction between the atomic groups X = Y is weakened by the bulk of the substituent Y, and ions easily move during the charge / discharge reaction. Therefore, the charge / discharge reaction proceeds smoothly, and charging in a short time becomes possible. Since the charge / discharge reaction proceeds smoothly as described above, the proportion of the electrode active material that can be effectively used increases, and discharge at a high output becomes possible.

In addition, since the organic compound has introduced a plurality of electrochemically active double bonds, it has high reactivity with cations such as lithium ions, has high charge / discharge efficiency, and high capacity density electrode activity. A substance can be obtained.

Therefore, a secondary battery using such an electrode active material has a large energy density, can be discharged at a high output, has good cycle characteristics with little capacity decrease even after repeated charge and discharge, and has stable battery characteristics. It becomes possible to obtain a secondary battery with a long life.

As the sterically bulky substituent Y described above, at least one selected from the group represented by (1a) to (1l) can be used, and the substituent Y and the specific element X are They are combined to form one atomic group X = Y.

Here, R ₁ to R ₃ are a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted Alkoxyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylamino group, substituted or unsubstituted alkylamino group, substituted or unsubstituted thioaryl group, substituted or unsubstituted Substituted thioalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted formyl group, substituted or unsubstituted silyl group, substituted or unsubstituted boryl group, substituted or unsubstituted stannyl group, substituted or unsubstituted Cyano group, substituted or unsubstituted nitro group, substituted or unsubstituted nitro Seo group, a substituted or unsubstituted amino group, a substituted or unsubstituted imino group, shows a substituted or unsubstituted carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, and at least one kind of halogen atoms. R ₁ to R ₃ include the same case and include a case where they are connected to each other to form a saturated or unsaturated ring.

And as an organic compound (1st Embodiment) which contains several atomic group X = Y in a structural unit, what is shown to General formula (2) can be mentioned, for example.

In the general formula (2), R ₄ and R ₅ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted cyclohexane. Alkyl group, substituted or unsubstituted alkoxyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylamino group, substituted or unsubstituted alkylamino group, substituted or unsubstituted Thioaryl group, substituted or unsubstituted thioalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted formyl group, substituted or unsubstituted silyl group, substituted or unsubstituted boryl group, substituted or unsubstituted Stannyl group, substituted or unsubstituted cyano group, substituted or unsubstituted nitro group, substituted or unsubstituted Represents at least one of an unsubstituted nitroso group, a substituted or unsubstituted amino group, a substituted or unsubstituted imino group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, and a halogen atom. R ₄ and R ₅ include the same case and include a case where they are connected to each other to form a saturated or unsaturated ring. Further, the specific element X and the substituent Y in the atomic group X = Y may be the same or different.

Further, at least one of R ₄ and R ₅ is N—R ′ (R ′ represents at least one of one or more hydrogen atoms, alkyl groups, aryl groups, and oxygen radicals, or a combination thereof. It is preferable that the charging / discharging reaction is further promoted, charging can be performed in a short time, and discharging at a higher output is possible.

In addition, as long as the said substituent Y belongs to the above-mentioned category, it is possible to repeatedly use one kind of substituent Y or to use two or more kinds of substituents Y in combination. Since the amount of charge that can be accumulated per unit mass of the active material becomes smaller as the value of increases, the molecular weight per atomic group X = Y is preferably up to about 250.

In the above organic compound, two electrons are involved in the reaction in the battery electrode reaction to form a complex salt. Chemical reaction formula (3) shows an example of a charge / discharge reaction expected when Li is used as the cation of the electrolyte salt.

Further, as a second embodiment of the organic compound, there can be mentioned one represented by the general formula (4) in which a linking group Z is interposed between atomic groups X = Y.

In the general formula (4), R ₆ and R ₇ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted cyclohexane. Alkyl group, substituted or unsubstituted alkoxyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylamino group, substituted or unsubstituted alkylamino group, substituted or unsubstituted Thioaryl group, substituted or unsubstituted thioalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted formyl group, substituted or unsubstituted silyl group, substituted or unsubstituted boryl group, substituted or unsubstituted Stannyl group, substituted or unsubstituted cyano group, substituted or unsubstituted nitro group, substituted or unsubstituted Represents at least one of an unsubstituted nitroso group, a substituted or unsubstituted amino group, a substituted or unsubstituted imino group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, and a halogen atom. R ₆ and R ₇ include the same case and include the case where they are connected to each other to form a saturated or unsaturated ring. The linking group Z is CH ₂ , CF ₂ , O, S, SO ₂ , Se, and N—R ′ (R ′ represents at least one of a hydrogen atom, an alkyl group, an aryl group, and an oxygen radical. .) Shows at least one selected from the above.

In addition, the specific element X and the substituent Y in the atomic group X = Y may be the same or different.

By interposing the linking group Z between the atomic groups X = Y in this way, the intermolecular interaction between the atomic groups is further weakened, the movement of ions during the charge / discharge reaction is further promoted, and the charge / discharge reaction is promoted. Since it proceeds more smoothly, it is possible to further increase the output.

Further, it is preferable that at least one of R ₆ and R ₇ contains the above-mentioned N—R ′, which promotes further progress of the charge / discharge reaction and enables discharge at a higher output.

Also in this case, as in the first embodiment, if the substituent Y belongs to the above category, one type of substituent Y may be used repeatedly, or two or more types of substituent Y may be used. However, when the molecular weight is increased, the amount of charge that can be accumulated per unit mass of the active material is reduced. Therefore, the molecular weight per atomic group X = Y is preferably up to about 250. .

In the above organic compound, two electrons are involved in the reaction in the electrode reaction to form a complex salt. The chemical reaction formula (5) shows an example of a charge / discharge reaction expected when Li is used as a cation of an electrolyte salt.

And as an organic compound which belongs to the category of the above general formula (2) or (4), for example, organic compounds represented by chemical formulas (6a) to (6k) can be mentioned.

The molecular weight of the organic compound constituting the electrode active material is not particularly limited. However, in the case of a low molecular weight molecule having a small molecular weight, it is preferably a polymer because it may be easily dissolved in the electrolyte. However, since the appearance of the effect desired by the present invention depends on the structure of a plurality of atomic groups X = Y, when the portion other than the atomic group X = Y becomes large, the capacity stored per unit mass, that is, Capacity density is reduced. Therefore, from such a viewpoint, it is desirable to appropriately select and set the molecular weight of the organic compound.

In addition, when it uses as a polymer of the organic compound mentioned above, molecular weight and molecular weight distribution are not specifically limited.

Next, a secondary battery using the electrode active material will be described in detail.

FIG. 1 is a cross-sectional view showing a coin-type secondary battery as an embodiment of a secondary battery according to the present invention. In this embodiment, the electrode active material of the present invention is used as a positive electrode active material. ing.

The battery can 1 has a positive electrode case 2 and a negative electrode case 3, and both the positive electrode case 2 and the negative electrode case 3 are formed in a disk-like thin plate shape. In the center of the bottom of the positive electrode case 2 that constitutes the positive electrode current collector, a positive electrode 4 in which a mixture containing a positive electrode active material (electrode active material) and a conductive auxiliary agent (conductive material) is formed into a sheet shape is disposed. Yes. A separator 5 formed of a porous sheet or film such as a microporous film, a woven fabric, or a nonwoven fabric is laminated on the positive electrode 4, and a negative electrode 6 is laminated on the separator 5. As the negative electrode 6, for example, a stainless steel foil or a copper foil overlaid with a lithium metal foil, or a lithium foil occlusion material such as graphite or hard carbon applied to a copper foil can be used. A negative electrode current collector 7 made of metal is laminated on the negative electrode 6, and a metal spring 8 is placed on the negative electrode current collector 7. The electrolyte 9 is filled in the internal space, and the negative electrode case 3 is fixed to the positive electrode case 2 against the urging force of the metal spring 8 and sealed with a gasket 10.

Next, an example of a method for manufacturing the secondary battery will be described in detail.

First, an electrode active material is formed into an electrode shape. For example, the electrode active material is mixed with a conductive auxiliary agent and a binder, and a solvent is added to form a slurry. The slurry is applied on the positive electrode current collector by an arbitrary coating method, and dried to obtain the positive electrode. Form.

Here, the conductive auxiliary agent is not particularly limited, for example, carbonaceous fine particles such as graphite, carbon black, and acetylene black, vapor grown carbon fibers, carbon nanotubes, carbon fibers such as carbon nanohorns, polyaniline, Conductive polymers such as polypyrrole, polythiophene, polyacetylene, and polyacene can be used. Further, two or more kinds of conductive assistants can be mixed and used. The content of the conductive auxiliary agent in the positive electrode 4 is desirably 10 to 80% by mass.

Also, the binder is not particularly limited, and various resins such as polyethylene, polyvinylidene fluoride, polyhexafluoropropylene, polytetrafluoroethylene, polyethylene oxide, carboxymethylcellulose, and the like can be used.

Further, the solvent is not particularly limited, and examples thereof include basic solvents such as dimethyl sulfoxide, dimethylformamide, 1-methyl-2-pyrrolidone, propylene carbonate, diethyl carbonate, dimethyl carbonate, and γ-butyrolactone, acetonitrile, Nonaqueous solvents such as tetrahydrofuran, nitrobenzene, and acetone, protic solvents such as methanol and ethanol, water, and the like can be used.

Also, the type of organic solvent, the compounding ratio of the organic compound and the organic solvent, the type of additive and the amount of the additive, and the like can be arbitrarily set in consideration of the required characteristics and productivity of the secondary battery. Next, the positive electrode 4 is impregnated into the electrolyte 9 so that the electrolyte 9 is impregnated with the positive electrode 4, and then the positive electrode 4 at the bottom center of the positive electrode case 2 constituting the positive electrode current collector is placed. Next, the separator 5 impregnated with the electrolyte 9 is laminated on the positive electrode 4, the negative electrode 6 and the negative electrode current collector 7 are sequentially laminated, and then the electrolyte 9 is injected into the internal space. Then, a metal spring 8 is placed on the negative electrode current collector 7, and a gasket 10 is arranged on the periphery, and the negative electrode case 3 is fixed to the positive electrode case 2 with a caulking machine or the like, and the outer casing is sealed. A type secondary battery is produced.

Incidentally, the electrolyte 9 interposed between the negative electrode 6, which is a counter electrode of the positive electrode 4 and the positive electrode 4 performs a charge carrier transport between the electrodes, but as such a electrolyte 9, at room temperature for 10 ^- Those having an ionic conductivity of ⁵ to 10 ⁻¹ S / cm can be used. For example, an electrolytic solution in which an electrolyte salt is dissolved in an organic solvent can be used.

Here, as the electrolyte salt, for example, LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ or the like can be used.

As the organic solvent, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide, dimethylacetamide, 1-methyl-2-pyrrolidone, etc. are used. be able to.

Further, a solid electrolyte may be used as the electrolyte 9. Examples of the polymer compound used in the solid electrolyte include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-monofluoroethylene copolymer, and fluoride compound. Vinylidene fluoride polymers such as vinylidene-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and acrylonitrile-methyl methacrylate copolymer Polymer, acrylonitrile-methyl acrylate copolymer, acrylonitrile-ethyl methacrylate copolymer, acrylonitrile-ethyl acrylate copolymer, acrylonitrile-methacrylic acid copolymer, acrylonitrile-acrylic Examples thereof include acrylonitrile polymers such as phosphoric acid copolymers, acrylonitrile-vinyl acetate copolymers, polyethylene oxide, ethylene oxide-propylene oxide copolymers, and polymers of these acrylates and methacrylates. it can. Further, these polymer compounds containing an electrolytic solution in a gel form may be used as the electrolyte 9 or only a polymer compound containing an electrolyte salt may be used as the electrolyte 9 as it is.

Thus, since the electrode of the present invention contains the electrode active material and the conductive material described above, the charge / discharge efficiency is good, the battery can be charged in a short time, and the output can be increased.

In addition, since the electrode active material of the secondary battery is reversibly oxidized or reduced by charge and discharge, it has a different structure and state in the charged state, the discharged state, or the state in the middle thereof. The electrode active material is contained in at least one of a reaction starting material in a discharge reaction (a material that causes a chemical reaction in a battery electrode reaction), a product (a material resulting from a chemical reaction), and an intermediate product. . As a result, a long-life secondary battery having a large energy density, capable of being charged quickly, capable of discharging at a high output, having good cycle characteristics with little decrease in capacity even after repeated charge and discharge, and having stable battery characteristics is obtained. It becomes possible.

In addition, the secondary battery of the present invention has at least two discharge voltages in the discharge reaction, thereby realizing a high-capacity density secondary battery across a plurality of voltages.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the above-listed chemical formulas (6a) to (6k) are only examples of the organic compound that is the main component of the electrode active material, and the present invention is not limited thereto. That is, if the structural unit contains a pair of atomic groups in which a predetermined substituent Y that is sterically bulky is bonded to the specific element X, the battery electrode reaction represented by the chemical reaction formula (3) or (5) is performed. Since it progresses, it is possible to obtain a desired secondary battery having a large energy density and excellent stability.

In this embodiment, the coin-type secondary battery has been described. However, it is needless to say that the battery shape is not particularly limited, and can be applied to a cylindrical type, a square type, a sheet type, and the like. Also, the exterior method is not particularly limited, and a metal case, mold resin, aluminum laminate film, or the like may be used.

In this embodiment, the electrode active material is used as the positive electrode active material, but it is also useful to use it as the negative electrode active material.

Next, specific examples of the present invention will be described.

In addition, the Example shown below is an example and this invention is not limited to the following Example.

[Synthesis of organic compounds]
A reaction product of N, N-dimethylselenourea and succinyl chloride (hereinafter referred to as “compound A”) (6a) was synthesized according to the following synthesis scheme (A).

First, 0.9 g of N, N-dimethylselenourea (6a ′): was dissolved in 50 mL of pure water. Next, after the whole was cooled to 0 ° C., an aqueous solution containing 0.47 g of succinyl chloride (6a ″) was added dropwise with stirring. The stirring was continued for 1 hour, and N, N-dimethylselenourea (6a ′) and Succinyl chloride (6a ″) was reacted to prepare Compound A. The compound A thus obtained was washed and dried to obtain a light brown solid.

[Production of secondary battery]
Compound A: 300 mg as a positive electrode active material (electrode active material), graphite powder as a conductive auxiliary agent: 600 mg, and polytetrafluoroethylene as a binder: 100 mg were weighed and kneaded while mixing uniformly. Was made. Subsequently, this mixture was pressure-molded to obtain a sheet-like member having a thickness of about 150 μm. Thereafter, this sheet-like member was dried in a vacuum at 70 ° C. for 1 hour, and then punched into a circle having a diameter of 12 mm to produce a positive electrode containing Compound A. Next, the positive electrode was impregnated with the electrolytic solution, and the electrolytic solution was infiltrated into the voids in the positive electrode. Here, as the electrolytic solution, a mixed solution in which LiPF ₆ was dissolved in ethylene carbonate / diethyl carbonate as an organic solvent so that the molar concentration of LiPF ₆ (electrolyte salt) was 1.0 mol / L was used. The mixing ratio of ethylene carbonate and diethyl carbonate was ethylene carbonate: diethyl carbonate = 30: 70 in volume%.

Next, this positive electrode was placed on a positive electrode current collector, and a separator having a thickness of 20 μm made of a polypropylene porous film impregnated with the electrolytic solution was further laminated on the positive electrode, and further a stainless steel current collector plate The negative electrode which stuck lithium on both surfaces was laminated | stacked on the separator. Then, a metal spring is placed on the current collector, and the negative electrode case is joined to the positive electrode case in a state where a gasket is provided on the periphery, and the outer case is sealed by a caulking machine, and the compound A, the negative electrode are used as the positive electrode active material A sealed coin-type battery having metallic lithium as an active material was produced.

[Confirmation of secondary battery operation]
The coin-type battery produced as described above was charged with a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged with a constant current of 0.1 mA until it reached 1.5 V. As a result, this battery was confirmed to be a secondary battery having a discharge capacity of 0.2 mAh having a voltage flat portion at a charge / discharge voltage of 1.5 to 3.2 V.

Thereafter, charging and discharging were repeated 10 cycles in the range of 1.5 to 4.0 V. As a result, it was found that the secondary battery had a long cycle life of 50% or more of the initial value even after 10 cycles, and little decrease in capacity even after repeated charge and discharge.

[Synthesis of organic compounds]
A condensate of selenourea and succinyl chloride (hereinafter referred to as “compound B”) (6c) was synthesized according to the following synthesis scheme (B).

First, 0.62 g of selenourea (6c ′) was dissolved in 50 mL of pure water. Next, after the whole was cooled to 0 ° C., an aqueous solution containing succinyl chloride (6c ″): 0.77 g was added dropwise with stirring. Stirring was continued for 1 hour to react selenourea with succinyl chloride to produce Compound B. The compound B thus obtained was washed and dried to obtain a light brown solid.

[Production of secondary battery]
A coin-type battery was produced in the same manner as in Example 1 except that the compound B was used as the positive electrode active material in place of the compound A in Example 1.

[Confirmation of secondary battery operation]
The coin-type battery was charged with a constant current of 0.1 mA until the voltage reached 3.8 V, and then discharged to 1.5 V with a constant current of 0.1 mA. As a result, it was confirmed that this battery was a secondary battery having a discharge capacity of 0.2 mAh having a flat voltage portion at a charge / discharge voltage of 1.5 to 3.2 V.

Thereafter, charging and discharging were repeated 10 cycles in the range of 2.0 to 4.0 V. As a result, it was found that the secondary battery had a long cycle life of 50% or more of the initial value even after 10 cycles, and little decrease in capacity even after repeated charge and discharge.

[Production of secondary battery]
Dimethyl 1,2,5-thiadiazole-3,4-dicarboxylate (hereinafter referred to as “Compound C”) represented by the chemical formula (6d) was prepared.

And it replaced with the compound A of Example 1, and produced the coin-type battery by the method similar to Example 1 except having used the said compound C for the positive electrode active material.

[Confirmation of secondary battery operation]
The coin-type battery was charged with a constant current of 0.1 mA until the voltage reached 3.8 V, and then discharged to 1.5 V with a constant current of 0.1 mA. As a result, it was confirmed that this battery was a secondary battery having a discharge capacity of 0.22 mAh having a flat voltage portion at a charge / discharge voltage of 2.0 to 3.5 V.

Thereafter, charging and discharging were repeated 10 cycles in the range of 1.5 to 4.0 V. As a result, it was found that the secondary battery had a long cycle life of 50% or more of the initial value even after 10 cycles, and little reduction in capacity even after repeated charge and discharge.

[Production of secondary battery]
Diethyl 1,2,5-thiadiazole-3,4-dicarboxylate (hereinafter referred to as “Compound D”) represented by the chemical formula (6e) was prepared.

And it replaced with the compound A of Example 1, and produced the coin-type battery by the method similar to Example 1 except having used the said compound D for the positive electrode active material.

[Confirmation of secondary battery operation]
The coin-type battery was charged with a constant current of 0.1 mA until the voltage reached 3.8 V, and then discharged with a constant current of 0.1 mA to 1.5 V. As a result, this battery was confirmed to be a secondary battery having a discharge capacity of 0.21 mAh having a flat voltage portion at a charge / discharge voltage of 2.0 to 3.5 V.

[Production of secondary battery]
4,4′-diethyl-5,5′-dipropyl- (3,3 ′) biisoxazoyl (hereinafter referred to as “Compound E”) represented by the chemical formula (6 g) was prepared.

And it replaced with the compound A of Example 1, and produced the coin-type battery by the method similar to Example 1 except having used the said compound E for the positive electrode active material.

[Production of secondary battery]
2- (4- (2,2-dicyanovinyl) benzylidene) malonitrile (hereinafter referred to as “Compound F”) represented by the chemical formula (6j) was prepared.

And it replaced with the compound A of Example 1, and produced the coin-type battery by the method similar to Example 1 except having used the said compound F for the positive electrode active material.

[Confirmation of secondary battery operation]
The coin-type battery was charged with a constant current of 0.1 mA until the voltage reached 3.8 V, and then discharged to 1.5 V with a constant current of 0.1 mA. As a result, it was confirmed that this battery was a secondary battery having a discharge capacity of 0.24 mAh having a flat voltage portion at a charge / discharge voltage of 2.0 to 3.5 V.

する Realizes a stable secondary battery with high energy density, high output, good cycle characteristics with little decrease in capacity even after repeated charge and discharge.

4 Positive electrode 6 Negative electrode 9 Electrolyte

Claims

An electrode active material used as an active material of a secondary battery that repeats charging and discharging by a battery electrode reaction,
The sterically bulky substituent Y is mainly composed of an organic compound containing a plurality of atomic groups X = Y bonded to a specific element X selected from C, Si and P in the constituent unit. Electrode active material.
The substituent Y is

[Wherein R 1 to R 3 are a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted cycloalkyl group, a substituted Or an unsubstituted alkoxyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted thioaryl group, Substituted or unsubstituted thioalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted formyl group, substituted or unsubstituted silyl group, substituted or unsubstituted boryl group, substituted or unsubstituted stannyl group, substituted Or unsubstituted cyano group, substituted or unsubstituted nitro group, substituted or unsubstituted Nitroso group, a substituted or unsubstituted amino group, a substituted or unsubstituted imino group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, and represents at least one kind of halogen atom, R 1 to R 3 include the same case and include a case where they are linked to each other to form a saturated or unsaturated ring. ]
The electrode active material according to claim 1, wherein the electrode active material is at least one selected from the group represented by:
The organic compound has the general formula

[Wherein R 4 and R 5 are a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted cycloalkyl group, a substituted Or an unsubstituted alkoxyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted thioaryl group, Substituted or unsubstituted thioalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted formyl group, substituted or unsubstituted silyl group, substituted or unsubstituted boryl group, substituted or unsubstituted stannyl group, substituted Or unsubstituted cyano group, substituted or unsubstituted nitro group, substituted or unsubstituted Nitroso group, a substituted or unsubstituted amino group, a substituted or unsubstituted imino group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, and represents at least one kind of halogen atom, R 4 , R 5 includes the same case, and includes a case where they are connected to each other to form a saturated or unsaturated ring.
The electrode active material according to claim 1, wherein the electrode active material is represented by:
At least one of R 4 and R 5 is N—R ′ (R ′ is at least one selected from one or more hydrogen atoms, alkyl groups, aryl groups, and oxygen radicals, or a combination thereof) The electrode active material according to claim 3, further comprising:
The organic compound has the general formula

[Wherein R 6 and R 7 are a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted cycloalkyl group, a substituted Or an unsubstituted alkoxyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted thioaryl group, Substituted or unsubstituted thioalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted formyl group, substituted or unsubstituted silyl group, substituted or unsubstituted boryl group, substituted or unsubstituted stannyl group, substituted Or unsubstituted cyano group, substituted or unsubstituted nitro group, substituted or unsubstituted Nitroso group, a substituted or unsubstituted amino group, a substituted or unsubstituted imino group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, and represents at least one kind of halogen atom, R 6 and R 7 include the same case and include a case where they are connected to each other to form a saturated or unsaturated ring, and Z represents CH 2 , CF 2 , O, S, SO 2 , Se, and N—R ′. (R ′ represents at least one selected from one or more hydrogen atoms, alkyl groups, aryl groups, and oxygen radicals, or a combination thereof) or at least one selected from a combination thereof Indicates. ]
The electrode active material according to claim 1, wherein the electrode active material is represented by:
6. The electrode active material according to claim 5, wherein at least one of R 6 and R 7 contains the NR ′.
An electrode comprising the electrode active material according to any one of claims 1 to 6 and a conductive material.
The electrode active material according to any one of claims 1 to 6 is contained in any one of a reaction starting material, a product, and an intermediate product in at least a discharge reaction of a battery electrode reaction. Next battery.
A secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode contains the electrode active material according to any one of claims 1 to 6.