JP4468058B2 - Secondary battery and electrode active material for secondary battery - Google Patents

Description

  The present invention relates to an electrochemical element having high energy density and excellent cycle characteristics and rapid charge / discharge characteristics, and an electrode active material used therefor.

  In recent years, with the development of mobile communication devices and portable electronic devices, the demand for their power sources has become very large. Batteries, in particular, lithium secondary batteries that can be repeatedly charged and discharged, have high electromotive force, high energy density, and can be used repeatedly. Therefore, they are widely used as power sources for portable electronic devices and the like.

  However, with the reduction in size and weight of portable electronic devices, there is an increasing demand for higher energy density of batteries, and the emergence of new electrode materials having higher energy density is desired. Against this background, efforts for material development have been actively carried out with the aim of increasing the energy density of electrode materials that are directly linked to increasing the energy density of batteries.

In recent years, studies have been made on using an organic compound as an electrode material in order to produce a lighter battery having a higher energy density. The organic compound has a light specific gravity of about 1 g / cm ³ and is lighter than an oxide such as lithium cobaltate currently used as a material for lithium secondary batteries. For this reason, it becomes possible to produce a lighter and higher capacity battery.

For example, Patent Documents 1 and 2 propose lithium secondary batteries using an organic sulfur compound having a disulfide bond as an electrode material. This organic sulfur compound is most simply represented as M ^{+ −} −S−R−S ⁻ −M ⁺ . Here, R represents an aliphatic or aromatic organic group, S represents sulfur, and M ⁺ represents a proton or a metal cation. The compounds bind to each other via an S-S bond by electrochemical oxidation ^{reactions, M + - - S-R} -S-S-R-S-S-R-S - -M + form such as To polymerize. The polymer thus produced returns to the original monomer by an electrochemical reduction reaction. In the lithium secondary battery, this reaction is used for the charge / discharge reaction.

Patent Document 3 also proposes the use of elemental sulfur as an electrode material.
However, in either case, the capacity can be increased, but there is a problem that the cycle characteristics are low. This is because in the dissociation / recombination of disulfide bonds, which is the oxidation-reduction reaction mechanism of sulfur-based materials, once the bonds are dissociated, the molecules diffuse and leave, and the frequency of recombination decreases. In addition, the fact that the frequency of recombination is low once the lines are disconnected means that all the reactive sites cannot react even if they have a theoretically high energy density. This cannot actually be a battery having a high energy density.
US Pat. No. 5,833,048 US Pat. No. 2,715,778 US Pat. No. 5,523,179

  As described above, in an electrochemical element having a light and high energy density using an organic sulfur compound having a disulfide moiety as an electrode reaction site as an electrode material, the structural change of the organic sulfur compound accompanying a redox reaction is large. There is a problem that cycle characteristics are low. The present invention has been made in view of this point, and an object of the present invention is to improve cycle characteristics of an electrochemical element that is lightweight and has a high energy density.

The first secondary battery of the present invention has a positive electrode, a negative electrode, and an electrolyte, and the electrolyte is a salt, a solid electrolyte, or a gel electrolyte dissolved in an organic solvent, and the positive electrode has a general formula ( 1a):

(Wherein R ^{1 to} R ⁴ are each independently a chain or cyclic aliphatic group, a hydrogen atom, a methyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, or a nitroso group, and R ⁵ , R ⁶ are each independently a chain or cyclic aliphatic group or a hydrogen atom, and the aliphatic group is selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. And a compound having a structure represented by (2) as a positive electrode active material.
The second secondary battery of the present invention has a positive electrode, a negative electrode, and an electrolyte, and the electrolyte is a salt, a solid electrolyte, or a gel electrolyte dissolved in an organic solvent, and the negative electrode has a general formula ( 1b):

(Wherein R ^{1 to} R ⁴ are each independently a chain or cyclic aliphatic group, a hydrogen atom, a methyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, or a nitroso group, and R ⁵ , R ⁶ are each independently a chain or cyclic aliphatic group or a hydrogen atom, and the aliphatic group is selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. And a compound having a structure represented by the formula (2) as a negative electrode active material.
The third secondary battery of the present invention has a positive electrode, a negative electrode, and an electrolyte, and the electrolyte is a salt, a solid electrolyte, or a gel electrolyte dissolved in an organic solvent, and the positive electrode has the general formula (2 ):

(Wherein R ^{1 to} R ⁴ and R ^{7 to} R ¹⁰ are each independently a chain or cyclic aliphatic group, hydrogen atom, methyl group, hydroxyl group, cyano group, amino group, nitro group or nitroso group. And the aliphatic group includes at least one selected from the group consisting of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom and halogen atom). It is characterized by including as a positive electrode active material.
The compound is preferably a polymer compound obtained by polymerizing the structure represented by the general formula (1a).
The compound is preferably a polymer compound in which a structure represented by the general formula (1a) and a polyacetylene chain or a polymethyl methacrylate chain as a main chain are combined.
Moreover, this invention relates to the electrode active material for secondary batteries which consists of a compound which has a structure represented by said general formula (1a), (1b) or (2).

The electrolyte preferably contains at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, and dimethylformamide as a solvent.
The electrolyte preferably contains at least one salt selected from the group consisting of alkali metal or alkaline earth metal halide salts, perchlorate salts, and fluorine compound salts .

In the first and third secondary batteries of the present invention, the negative electrode includes a carbon material, lithium metal, lithium-containing composite nitride, lithium-containing composite titanium oxide, a composite of tin and carbon, tin and another metal, It is preferable that at least one selected from the group consisting of a composite of the above, an alloy of silicon and another metal, and an oxide of silicon is included as the negative electrode active material.
In the second secondary battery of the present invention, it is preferable that the positive electrode includes a metal oxide as a positive electrode active material.
It is preferable that the positive electrode further contains a conductive additive.

According to the present invention, by using a compound having a structure represented by the general formula (1a), (1b) or (2) as an electrode active material, an electrochemical device that is lightweight, has high energy density, and has excellent cycle characteristics. Can be obtained.

The electrochemical element of the present invention is an electrochemical element that takes out electron transfer associated with an oxidation-reduction reaction as electric energy, and includes a positive electrode, a negative electrode, and an electrolyte, and at least one of the positive electrode and the negative electrode has a general formula ( 1a ):

( Wherein R ^{1 to} R ⁴ are each independently a chain or cyclic aliphatic group, a hydrogen atom , a methyl group , a hydroxyl group, a cyano group, an amino group, a nitro group, or a nitroso group , and R ⁵ , R ⁶ are each independently a chain or cyclic aliphatic group or a hydrogen atom , and the aliphatic group is selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. And a compound having a structure represented by the following formula (hereinafter also referred to as an active material compound).
Further, the electrochemical element of the present invention is an electrochemical element that takes out electron transfer associated with the oxidation-reduction reaction as electric energy, and includes a positive electrode, a negative electrode, and an electrolyte, and at least one of the positive electrode and the negative electrode is General formula (1b):

(Wherein R ^{1 to} R ⁴ are each independently a chain or cyclic aliphatic group, a hydrogen atom, a methyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, or a nitroso group, and R ⁵ , R ⁶ are each independently a chain or cyclic aliphatic group or a hydrogen atom, and the aliphatic group is selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. And a compound having a structure represented by the following formula (hereinafter also referred to as an active material compound).
The active material compound performs an oxidation-reduction reaction in the battery as an electrode active material, and exchanges electrons.

The active material compound can perform a redox reaction without greatly changing its structure. The mechanism is as follows.
That is, the active material compound has structural symmetry and a planar structure. In addition, the active material compound has a carbon-carbon double bond at the center of the molecule and a cyclic structure containing a hetero atom such as sulfur or oxygen. A heteroatom has a lone pair of electrons. Therefore, conjugation by π electrons is formed on the molecule. This π-electron conjugated site extending throughout the molecule can exchange electrons. Transfer of electrons proceeds as an oxidation / reduction reaction of the active material compound.
For example, during the reduction reaction (discharge reaction), the active material compound is reduced, and the cation in the electrolyte is coordinated to the reduced molecule. During the subsequent oxidation reaction (charging reaction), the cations coordinated to the active material compound are eliminated. This reaction can be used as a battery reaction.

When the active material compound is oxidized during the oxidation reaction (charging reaction), the anion of the electrolyte coordinates to the oxidized molecule. During the subsequent reduction reaction (discharge reaction), the anion coordinated with the active material compound is eliminated.
In such a series of oxidation-reduction reactions, it is considered that the active material compound does not cause a large structural change such as bond separation / recombination. If the molecule of the active material compound undergoes a major structural change in accordance with the oxidation-reduction reaction, the structural change of the molecule is required when the next reaction is performed. Since large energy is required at this time, the reactivity is lowered. Therefore, the absence of a large structural change associated with the redox reaction indicates that the reaction can be performed efficiently.

  As described above, in the present invention, a compound having a π-electron conjugated site spread on a molecule as a redox reaction site is used as an electrode active material. In the above reaction mechanism, a large structural change of the skeleton of the active material does not occur with the redox reaction. Accordingly, structural deterioration of the active material due to repeated redox reactions is suppressed, so that excellent charge / discharge cycle characteristics can be obtained.

Furthermore, in the above reaction mechanism, a higher reaction rate can be expected as compared with a binding / disconnection reaction caused by a normal organic sulfur compound. When the reaction rate is increased, excellent rate characteristics can be expected as battery characteristics, which is advantageous for rapid charge / discharge.
Examples of the compound represented by the general formula ( 1a ) include chemical formula (3):

The compound represented by these is preferable.
Moreover, as a compound represented by General formula (1b) , Chemical formula (4):

The compound represented by these is preferable. Since these compounds have the smallest molecular weight among the compounds represented by the general formula (1a) or (1b) , the energy density of the active material is the highest, and an electrochemical element having a high energy density can be obtained.
Moreover, the electrochemical element of this invention consists of a positive electrode, a negative electrode, and an electrolyte at the point from which a faster electrode reaction rate is obtained , and at least one of the said positive electrode and the said negative electrode is General formula (2):

(Wherein R ^{1 to} R ⁴ and R ^{7 to} R ¹⁰ are each independently a chain or cyclic aliphatic group, hydrogen atom , methyl group , hydroxyl group, cyano group, amino group, nitro group or nitroso group. And the aliphatic group includes a compound represented by the formula: at least one selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom, and a halogen atom .

The reason why the electrode reaction becomes faster in the case of the general formula (2) is shown below.
In the oxidation-reduction reaction of the compound represented by the general formula ( 1a ), electrons are transferred on two five-membered rings, and a two-step reaction occurs. The oxidation-reduction reaction of the compound represented by the general formula (2) is the same reaction as the general formula ( 1a ), but the two benzene rings arranged between two five-membered rings are used. The energy levels at which electrons are extracted from the member rings are close to each other, and the reaction proceeds in a pseudo-step. This is because the one-electron reacted structure and the two-electron reacted structure are very similar.
Examples of the compound represented by the general formula (2) include the chemical formula (5):

A compound represented by the formula (6):

A compound represented by the formula (7):

A compound represented by the formula (8):

The compound etc. which are represented by these are mentioned.
In general formulas (1a), (1b) and (2), R ^{1 to} R ⁴ and R ^{7 to} R ¹⁰ are preferably nitro groups (NO ₂ ). An electrochemical device having high voltage and excellent charge / discharge cycle characteristics can be obtained. Moreover, a cyano group (CN) is preferable. An electrochemical device having a high voltage and a high capacity can be obtained. A methyl group (CH ₃ ) is preferred. An electrochemical device having a high voltage and a high capacity and having excellent rate characteristics and cycle characteristics can be obtained.

Above general formula (1a), the aliphatic group used in ^{R 1 ~R 4, R 7 ~R} 10 in (1b) and (2), for example, an alkyl group, a cycloalkyl group, an alkoxy group, a hydroxyalkyl Group, thioalkyl group, aldehyde group, carboxylic acid group, halogenated alkyl group and the like. Further, the carbon number of the aliphatic group is not particularly limited, but the carbon number is preferably 1-6.

Moreover, as long as the active material compound has a structure represented by the general formula (1a), (1b) or (2) , a low molecular compound to a high molecular compound can be used. These may be used alone or in combination of two or more.

In the present invention, the high molecular compound means a compound having a molecular weight of 10,000 or more obtained by polymerizing a low molecular compound. A polymer compound has a property that it is less soluble in an electrolyte or the like than a low-molecular compound. Therefore, when a polymer compound is used as the electrode active material, elution of the active material into the electrolyte is suppressed, and the stability of the cycle characteristics is further enhanced.
The polymer compound is preferably a compound obtained by polymerizing the general formula (1a), (1b) or (2) . As such a compound, for example, the general formula (9):

(Wherein n is an integer of 1 or more). Since it is composed of a monomer having a low molecular weight, an active material having a high energy density can be obtained.
Moreover, as a high molecular compound, the compound which has a polyacetylene and a polymethylmethacrylate chain as a main chain is preferable. Moreover, it is preferable that two or more structures represented by the general formula (1a) or (1b) are included in one molecule. The molecular weight of the polyacetylene chain is preferably 10,000 to 200,000. As such a compound, for example, the general formula (10):

(Wherein n is an integer of 1 or more).
In addition, said compound may be used independently and may be used in combination of 2 or more type.
Active material compounds are particularly suitable for use as electrode active materials for secondary batteries among electrochemical elements, but can also be used for electrodes for primary batteries, electrolytic capacitors, various sensors, electrochromic elements, and the like. . Moreover, you may use an active material compound for the electrode of electrochemical elements other than these.

  In the secondary battery, the active material compound may be used for both the positive electrode and the negative electrode, or may be used for either one of them. When this compound is used for one of the electrodes, a material conventionally used as an active material for a secondary battery can be used for the other electrode active material without any particular limitation.

When the compound having the structure represented by the general formula (1a), (1b) or (2) is used as the positive electrode active material, examples of the negative electrode active material include carbon materials such as graphite and amorphous carbon, lithium Metals, lithium-containing composite nitrides, lithium-containing titanium oxides, composites of tin and carbon, composites of tin and other metals, alloys of silicon and other metals, silicon oxides, etc. it can.
In general formula (1a) as an anode active material, in the case of using a compound having a structure represented by (1b) or (2) as a positive electrode active material, for example, LiCoO _2, LiNiO _2, LiMn ₂ O ₄ A metal oxide such as can be used.

When a compound having a structure represented by the general formula (1a), (1b) or (2) is used as an electrode active material, a carbon material such as carbon black, graphite, acetylene black, etc. for the purpose of reducing electrode resistance; A conductive polymer such as polyaniline, polypyrrole, or polythiophene may be mixed with the electrode active material as a conductive auxiliary agent. Further, as an ion conduction auxiliary agent, a solid electrolyte made of polyethylene oxide or the like, or a gel electrolyte made of polymethyl methacrylate or the like may be mixed with the electrode active material.

  In order to improve the binding property of the constituent material of the substance in the electrode, a binder may be used. As the binder, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, polytetrafluoroethylene, styrene-butadiene copolymer, polypropylene, polyethylene, polyimide, Polyacrylic acid or the like can be used.

  As the positive electrode current collector or the negative electrode current collector, a metal foil made of nickel, aluminum, gold, silver, copper, stainless steel, an aluminum alloy, a metal mesh, a resin containing a conductive filler, or the like can be used. By applying carbon or the like on the current collector, the resistance value of the electrode is reduced, the current collector has a catalytic effect, or the current collector and the active material are chemically or physically bonded. May be.

  When a separator is interposed between the positive electrode and the negative electrode, the separator is impregnated with an electrolyte. The electrolyte is preferably composed of a solvent and a salt dissolved in the solvent. Further, the electrolyte itself may be gelled to have a function as a separator. In this case, it is preferable to impregnate the electrolyte with a matrix such as polyacrylonitrile, a polymer containing acrylate units or methacrylate units, or a copolymer of ethylene and acrylonitrile. It is preferable to use a crosslinked polymer for the matrix.

  Examples of salts contained in the electrolyte include halides of alkali metals such as lithium, sodium and potassium or alkaline earth metals such as magnesium, salts of fluorine-containing compounds represented by perchlorate and trifluoromethanesulfonate, etc. Is preferred. Specifically, lithium fluoride, lithium chloride, lithium perchlorate, lithium trifluoromethanesulfonate, lithium tetraborate fluoride, lithium bistrifluoromethylsulfonylimide, lithium thiocyanate, magnesium perchlorate, magnesium trifluoromethanesulfonate, Examples include sodium tetraborate fluoride. These may be used alone or in combination of two or more.

  As the solvent, for example, organic solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide and the like are preferably used.

A solid electrolyte may be used as the electrolyte. Examples of the solid electrolyte include Li ₂ S—SiS ₂ , Li ₂ S—P ₂ O ₅ , Li ₂ S—B ₂ S ₅ , Li ₂ S—P ₂ S ₅ —GeS ₂ , sodium / alumina (Al ₂ O ₃ ), Amorphous or low phase transition temperature (Tg) polyethers, amorphous vinylidene fluoride-6-propylene copolymer, blends of different polymers, polyethylene oxide, and the like.

  Next, the present invention will be described in detail based on examples. In each example, a coin-type battery was produced and the electrode active material was evaluated. The evaluation method was the same as the evaluation method for ordinary secondary batteries. Hereinafter, a test electrode manufacturing method, a coin-type battery manufacturing method, and battery characteristic evaluation will be described in order.

Example 1
(1) Method for producing test electrode The following operation was performed in an argon gas atmosphere using a dry box equipped with a gas purifier.
As an electrode active material, chemical formula (3):

Compound represented by (Te general formula (1a) smell, R ¹ ~ R ⁶ is a compound of hydrogen atoms) was used. The compound represented by the chemical formula (3) was synthesized according to Non-Patent Document 1 (Non-Patent Document 1: R. Carlier, P. Hapiot et al., Electrochem Acta, 46, 3269-3277, 2001).

  30 mg of the compound represented by the chemical formula (3) and 30 mg of acetylene black as a conductive auxiliary agent were mixed until uniform, and 1 ml of N-methyl-2-pyrrolidone was added as a solvent. For the purpose of binding the active material and the conductive additive to the obtained mixture, 5 mg of polyvinylidene fluoride was added as a binder and mixed until uniform to obtain a black slurry. This was cast on an aluminum foil current collector and vacuum dried at room temperature for 1 hour. After drying, this was punched into a disk shape having a diameter of 13.5 mm to obtain a test electrode.

(2) Method for Producing Coin-Type Battery Using the test electrode produced by the above method as a positive electrode, a coin-type battery obtained by punching lithium metal (thickness: 300 μm) into a 13.5 mm disc shape as a negative electrode is described below. It was produced by the procedure. A schematic longitudinal sectional view of the obtained coin-type battery is shown in FIG.

First, a test electrode (positive electrode) 12 was placed on the inner surface of the positive electrode case 11, and a separator 13 made of a porous polyethylene sheet was placed on the test electrode 12. Next, the electrolyte was injected into the positive electrode case 11. The electrolyte used was a solution of lithium hexafluorophosphate (LiPF ₆ ) at a concentration of 1.0 mol / L in a mixed solvent composed of ethylene carbonate and diethyl carbonate (weight ratio 1: 1).

  In addition, a sealing plate 16 was prepared in which metallic lithium (negative electrode) 14 was pressure-bonded to the inner surface and a sealing ring 15 was attached to the peripheral edge. Then, the metallic lithium 14 was made to face the test electrode 12, the case 11 was sealed with the sealing plate 16, and the opening end of the case 11 was crimped to the sealing ring 15 with a press machine to produce a coin-type battery for evaluation. .

(3) Battery Characteristic Evaluation The constant current charge / discharge of the produced coin-type battery was performed at an ambient temperature of 20 ° C. with a current value of 0.133 mA and a voltage range of 2.5 V to 4.5 V. 1, 50, 100 and The discharge capacity at the 300th cycle was determined. Moreover, the average discharge voltage with respect to the oxidation-reduction potential (Li / Li ⁺ ) of lithium was determined. As the average discharge voltage, the average value of the voltage at the time of discharge in the first cycle was used. The discharge voltage hardly changed until the 300th cycle. Even when the discharge curve is stepped due to the two-stage discharge reaction, the average value of the whole was obtained. The results are shown in Table 1.

  Moreover, the charge / discharge rate characteristics were evaluated. Here, constant current charging / discharging of the manufactured coin-type battery is performed at an ambient temperature of 20 ° C., a current value of 0.133, 0.665, 1.33, or 2.66 mA, and a voltage range of 2.5 V to 4.5 V. The discharge capacity at the 50th cycle at each current value was obtained. The results are shown in Table 2.

<< Comparative Example 1 >>
A coin-type battery was produced in the same manner as in Example 1 except that 2,5-dimercapto-1,3,4-thiadiazole (manufactured by Aldrich), which is an organic sulfur compound, was used as the active material of the test electrode. Evaluation was performed in the same manner. The results are shown in Tables 1 and 2.

Example 2
Instead of the compound represented by the chemical formula (3), the chemical formula (5):

A coin-type battery was prepared and evaluated in the same manner as in Example 1 except that the compound represented by The results are shown in Tables 1 and 2.

Example 3
Instead of the compound represented by the chemical formula (3), the chemical formula (8):

A coin-type battery was prepared and evaluated in the same manner as in Example 1 except that the compound represented by The results are shown in Tables 1 and 2.

Example 4
Instead of the compound represented by the chemical formula (3), the chemical formula (6):

A coin-type battery was prepared and evaluated in the same manner as in Example 1 except that the compound represented by The results are shown in Tables 1 and 2.

Example 5
Instead of the compound represented by the chemical formula (3), the chemical formula (7):

A coin-type battery was prepared and evaluated in the same manner as in Example 1 except that the compound represented by The results are shown in Tables 1 and 2.

[Consideration of evaluation results]
As shown in Table 1, in Comparative Example 1 in which an organic sulfur-based compound having a disulfide site as an electrode reaction site was used as an electrode active material, a capacity of 280 mAh / g was obtained at the time of initial discharge. The capacity decreased to 20 mAh / g, and a capacity of only about 15 mAh / g was obtained at the 300th cycle.
On the other hand, in Examples 1 to 5 in which the compound having the structure represented by the general formula (1) was used as the electrode active material, a high average discharge voltage near 3.5 V was obtained, and almost no discharge was observed even at the 300th cycle. No decrease in capacity was observed.

  The charge-discharge reaction mechanism of the organosulfur compound having a disulfide moiety used in Comparative Example 1 is based on an SS bond separation / recombination reaction. This reaction has low recombination properties because the reaction frequency is low and the molecular structure is greatly changed by the charge / discharge reaction. Therefore, although a high discharge capacity was obtained at the beginning of the cycle, it is considered that almost no discharge capacity was obtained at the 300th cycle. From the above, it can be seen that excellent cycle characteristics cannot be obtained when a compound having a reaction mechanism based on SS bond dissociation / recombination reaction is used as the electrode active material.

On the other hand, the compound having the structure represented by the general formula (1a) or (2) used in Examples 1 to 5 of the present invention hardly decreased the discharge capacity even after 300 cycles. It is thought that these compounds did not cause deterioration of the compounds themselves due to repeated charge and discharge because they only coordinate with anions and cations on the molecules in the charge and discharge reaction and do not cause a large change in the molecular structure. It is done.

From the above results, it can be seen that the electrochemical device using the compound having the structure represented by the general formula (1a) or (2) as an electrode active material has excellent cycle characteristics.
Further, as is apparent from the results in Table 2, it can be seen that an electrochemical device using a compound having a structure represented by the general formula (1a) or (2) as an electrode active material has excellent rate characteristics.

Example 6
Next, an example in which a polymer compound having a plurality of structures represented by the chemical formula (3) is used as an electrode active material will be described. Here, as a compound having a polyethylene chain as a main chain and having a plurality of structures represented by the chemical formula (3), the general formula (9):

(In the formula, n = 4 to 10 is satisfied).
A coin-type battery was fabricated in the same manner as in Example 1, except that 40 mg of the compound represented by the general formula (9) was used instead of 30 mg of the compound represented by the chemical formula (3). Then, constant current charging / discharging of the manufactured coin-type battery is performed at an ambient temperature of 20 ° C. with a current value of 0.133 mA and a voltage range of 2.5 V to 4.5 V, and discharges at 1, 50, 100, and 300 cycles. The capacities were determined in the same manner as in Example 1. The results are shown in Table 3.

Example 7
Next, an example in which a polymer compound having a plurality of structures represented by the chemical formula (3) is used as an electrode active material will be described. Here, as a compound having a polyacetylene chain as a main chain and having a plurality of structures represented by the chemical formula (3), the general formula (10):

(In the formula, n = 4 to 10 is satisfied).
A coin-type battery was fabricated in the same manner as in Example 1 except that 40 mg of the compound represented by the general formula (10) was used instead of 30 mg of the compound represented by the chemical formula (3). Then, constant current charging / discharging of the manufactured coin-type battery is performed at an ambient temperature of 20 ° C. with a current value of 0.133 mA and a voltage range of 2.5 V to 4.5 V, and discharges at 1, 50, 100, and 300 cycles. The capacities were determined in the same manner as in Example 1. The results are shown in Table 3.
From the results in Table 3, it can be seen that an electrochemical device using a polymer compound having a plurality of structures represented by the general formula ( 1a ) as an electrode active material also exhibits excellent cycle characteristics.

Example 8
Next, an example using a lithium-containing composite nitride as the negative electrode will be described. A coin-type battery was produced in the same manner as in Example 1 except that the following negative electrode was used.
The lithium-containing composite nitride is prepared by placing a lithium cobalt alloy having a Li / Co molar ratio of 2.6 / 0.4 in a copper container and holding the alloy in a nitrogen atmosphere at 800 ° C. for 2 hours. It was prepared by reacting with. After the reaction, the obtained black gray nitride was pulverized into a powder and used as a negative electrode active material.

When powder X-ray diffraction measurement of the obtained negative electrode active material was performed using CuKα rays, a diffraction pattern based on the same hexagonal crystal as lithium nitride (Li ₃ N) was observed. From this, it was confirmed that a single-phase solid solution in which Co was incorporated in the crystal structure of lithium nitride was obtained. The composition of the lithium-containing composite nitride synthesized at this time was Li _2.6 Co _0.4 N.

The Li _2.6 Co _0.4 N powder thus obtained, carbon powder, and polytetrafluoroethylene powder as a binder were sufficiently mixed at a weight ratio of 100: 25: 5 to obtain a negative electrode mixture. This negative electrode mixture was applied on a copper sheet, rolled, and the obtained electrode plate was punched into a disk shape having a diameter of 13.5 mm to obtain a negative electrode.

  As the positive electrode, the same test electrode as that prepared in Example 1 was used. Then, constant current charge / discharge of the produced coin-type battery was performed at an ambient temperature of 20 ° C. with a current value of 0.133 mA and a voltage range of 2.5 V to 4.5 V, and discharges at 1, 50, 100 and 300 cycles. The capacities were determined in the same manner as in Example 1. The results are shown in Table 4.

Example 9
Next, examples using lithium-containing composite titanium oxide as the negative electrode will be described. A coin-type battery was produced in the same manner as in Example 1 except that the following negative electrode was used.
LiTi ₅ O ₁₂ powder was used for the lithium-containing composite titanium oxide. LiTi ₅ O ₁₂ powder, carbon powder, and polytetrafluoroethylene powder as a binder were sufficiently mixed at a weight ratio of 100: 25: 5 to obtain a negative electrode mixture. This negative electrode mixture was applied on a copper sheet, rolled, and the obtained electrode plate was punched into a disk shape having a diameter of 13.5 mm to obtain a negative electrode.

As the positive electrode, the same test electrode as that prepared in Example 1 was used. Then, constant current charging / discharging of the manufactured coin-type battery is performed at an ambient temperature of 20 ° C. with a current value of 0.133 mA and a voltage range of 2.5 V to 4.5 V, and discharges at 1, 50, 100, and 300 cycles. The capacities were determined in the same manner as in Example 1. The results are shown in Table 4.
From the results of Table 4, using a compound having a structure represented by the general formula (1a) to one electrode active material, a lithium-containing composite nitride or the lithium-containing composite titanium oxide to the other electrode active material Electrical It can be seen that the chemical element also exhibits excellent cycle characteristics.

Example 10
Next, examples in which a compound having a structure represented by the general formula ( 1a ) is used as an active material for a positive electrode and a compound having a structure represented by the general formula (1b) is used as an active material for a negative electrode will be described. Here, chemical formula (7):

And a chemical formula (4) as a negative electrode active material:

The compound represented by this was used.
A coin-type battery was fabricated in the same manner as in Example 1 except that these were used for the positive electrode active material and the negative electrode active material. That is, instead of the compound represented by the chemical formula (3) and the metal lithium, a test electrode was prepared using a compound represented by the chemical formula (7) and a compound represented by the chemical formula (4), respectively. A coin-type battery was produced using the electrode as the positive electrode and the latter test electrode as the negative electrode. Then, constant current charging / discharging of the manufactured coin-type battery was performed at an ambient temperature of 20 ° C. with a current value of 0.133 mA and a voltage range of 0.3 V to 0.6 V, and discharges at 1, 50, 100, and 300 cycles. The capacities were determined in the same manner as in Example 1. The results are shown in Table 5.

From the results of Table 5, the positive electrode case of using the compound represented by the compound represented by formula (1a) and the negative electrode in formula (1b) to be in, it can be seen that excellent cycle characteristics can be obtained.

  The compound used in the electrochemical device of the present invention is particularly suitable for use as an electrode active material of a secondary battery, but can also be used in electrodes of primary batteries, electrolytic capacitors, various sensors, electrochromic devices and the like. .

It is a schematic longitudinal cross-sectional view of the coin-type battery produced in the Example of this invention.

Explanation of symbols

11 Positive electrode case 12 Test electrode 13 Separator 14 Metal lithium 15 Sealing ring 16 Sealing plate

Claims (28)

A positive electrode, a negative electrode, and an electrolyte;
The electrolyte is a salt dissolved in an organic solvent, a solid electrolyte, or a gel electrolyte,
The positive electrode has the general formula (1a):

(Wherein R ^{1 to} R ⁴ are each independently a chain or cyclic aliphatic group, a hydrogen atom, a methyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, or a nitroso group, and R ⁵ , R ⁶ are each independently a chain or cyclic aliphatic group or a hydrogen atom, and the aliphatic group is selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. A secondary battery comprising a compound having a structure represented by: at least one selected as a positive electrode active material. The secondary battery according to claim 1, wherein the compound is a polymer compound obtained by polymerization of a structure represented by the general formula (1a). The compound has the general formula (9):

The secondary battery according to claim 2, wherein n is an integer of 1 or more. The compound has a structure represented by formula (1a), a polymer compound formed by bonding a polyacetylene chain or a polymethyl methacrylate chain as a main chain secondary battery according to claim 1, wherein. The compound has the general formula (10):

The secondary battery according to claim 4, wherein n is an integer of 1 or more.   The secondary battery according to claim 1, wherein the positive electrode further includes a conductive additive. The negative electrode includes a carbon material, lithium metal, lithium-containing composite nitride, lithium-containing composite titanium oxide, a composite of tin and carbon, a composite of tin and other metals, an alloy of silicon and other metals, and The secondary battery according to claim 1, comprising at least one selected from the group consisting of silicon oxides as a negative electrode active material. 6. The electrolyte according to claim 1, wherein the electrolyte includes at least one salt selected from the group consisting of alkali metal or alkaline earth metal halide salts, perchlorate salts, and fluorine compound salts . Secondary battery.   The secondary battery according to claim 8, wherein the alkali metal is lithium.   The electrolyte comprises at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, and dimethylformamide as a solvent. The secondary battery in any one of. A positive electrode, a negative electrode, and an electrolyte;
The electrolyte is a salt dissolved in an organic solvent, a solid electrolyte, or a gel electrolyte,
The negative electrode has the general formula (1b):

(Wherein R ^{1 to} R ⁴ are each independently a chain or cyclic aliphatic group, a hydrogen atom, a methyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, or a nitroso group, and R ⁵ , R ⁶ are each independently a chain or cyclic aliphatic group or a hydrogen atom, and the aliphatic group is selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. A secondary battery comprising a compound having a structure represented by: at least one selected as a negative electrode active material.   The secondary battery according to claim 11, wherein the positive electrode includes a metal oxide as a positive electrode active material. The secondary battery according to claim 11, wherein the electrolyte includes at least one salt selected from the group consisting of a halide salt of an alkali metal or an alkaline earth metal, a perchlorate salt, and a salt of a fluorine compound .   The secondary battery according to claim 13, wherein the alkali metal is lithium.   12. The electrolyte according to claim 11, wherein the electrolyte includes at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, and dimethylformamide as a solvent. Secondary battery. A positive electrode, a negative electrode, and an electrolyte;
The electrolyte is a salt dissolved in an organic solvent, a solid electrolyte, or a gel electrolyte,
The positive electrode has the general formula (2):

(Wherein, R ¹ to R ⁴ and R ⁷ to R ¹⁰ are each independently a linear or cyclic aliphatic group, a hydrogen atom, a methyl group, a hydroxyl group, a cyano group, an amino group, a nitro group or a nitroso group And the aliphatic group includes at least one selected from the group consisting of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom and halogen atom). A secondary battery comprising a positive electrode active material.   The secondary battery according to claim 16, wherein the positive electrode further includes a conductive additive. The negative electrode includes a carbon material, lithium metal, lithium-containing composite nitride, lithium-containing composite titanium oxide, a composite of tin and carbon, a composite of tin and other metals, an alloy of silicon and other metals, and The secondary battery according to claim 16, comprising at least one selected from the group consisting of a composite containing a silicon oxide as a negative electrode active material. The secondary battery according to claim 16, wherein the electrolyte includes at least one salt selected from the group consisting of a halide salt of an alkali metal or an alkaline earth metal, a perchlorate salt, and a salt of a fluorine compound .   The secondary battery according to claim 19, wherein the alkali metal is lithium.   The electrolyte includes at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, and dimethylformamide as a solvent. Secondary battery. An electrode active material used for a secondary battery in which the electrolyte is a salt, a solid electrolyte, or a gel electrolyte dissolved in an organic solvent,
General formula (1a):

(Wherein R ^{1 to} R ⁴ are each independently a chain or cyclic aliphatic group, a hydrogen atom, a methyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, or a nitroso group, and R ⁵ , R ⁶ are each independently a chain or cyclic aliphatic group or a hydrogen atom, and the aliphatic group is selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. An electrode active material for a secondary battery, comprising: a compound having a structure represented by: The electrode active material for a secondary battery according to claim 22, wherein the compound is a polymer compound obtained by polymerization of a structure represented by the general formula (1a). The compound has the general formula (9):

24. The electrode active material for a secondary battery according to claim 23, wherein n is an integer of 1 or more. 23. The electrode active material for a secondary battery according to claim 22 , wherein the compound is a polymer compound in which a structure represented by the general formula (1a) and a polyacetylene chain or a polymethyl methacrylate chain as a main chain are combined . The compound has the general formula (10):

26. An electrode active material for a secondary battery according to claim 25, wherein n is an integer of 1 or more. An electrode active material used for a secondary battery in which the electrolyte is a salt, a solid electrolyte, or a gel electrolyte dissolved in an organic solvent,
General formula (1b):

(Wherein R ^{1 to} R ⁴ are each independently a chain or cyclic aliphatic group, a hydrogen atom, a methyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, or a nitroso group, and R ⁵ , R ⁶ are each independently a chain or cyclic aliphatic group or a hydrogen atom, and the aliphatic group is selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom and a halogen atom. An electrode active material for a secondary battery, comprising: a compound having a structure represented by: An electrode active material used for a secondary battery in which the electrolyte is a salt, a solid electrolyte, or a gel electrolyte dissolved in an organic solvent,
General formula (2):

(Wherein R ^{1 to} R ⁴ and R ^{7 to} R ¹⁰ are each independently a chain or cyclic aliphatic group, hydrogen atom, methyl group, hydroxyl group, cyano group, amino group, nitro group or nitroso group. And the aliphatic group includes at least one selected from the group consisting of oxygen atom, nitrogen atom, sulfur atom, silicon atom, phosphorus atom, boron atom and halogen atom). An electrode active material for a secondary battery.

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