JP2003007339A - Battery and manufacturing method of battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery and a manufacturing method of the battery, in which dissolving of a current collector into an electrolytic solution is suppressed. SOLUTION: The manufacturing method of the battery comprises a process of billing the electrolytic solution into a battery container in a state that a positive electrode and a negative electrode are arranged in the battery container, wherein the electrolytic solution is filled in a state that a potential is given between the positive electrode and the negative electrode. By giving the potential between the positive electrode and the negative electrode in the process of filling the electrolytic solution into the battery container, the potentials of the positive electrode and the negative electrtrode become lower than the dissolving potential of a positive electrode current collector and a negative electrode current collector, respectively. As a result, each current collector does not dissolve into the electrolytic solution, so that the deterioration of a self-discharging capability is suppressed in the battery manufactured by the above method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a battery, and more particularly to a method for manufacturing a battery in which elution of an electrode current collector into an electrolytic solution is suppressed.

[0002]

2. Description of the Related Art Against the background of recent energy and environmental problems, there is a demand for a technique for more effectively utilizing electric power.
As one of the technologies, research has been conducted on an electricity storage means capable of storing a large amount of electricity and efficiently extracting the stored electricity. As a storage means for electricity, a secondary battery having a large discharge capacity and a high discharge voltage and capable of being repeatedly charged and discharged is optimal.

As a secondary battery, for example, a lithium secondary battery in which lithium ions are discharged from the positive electrode and stored in the negative electrode during charging, and a discharging reaction in which lithium ions are discharged from the negative electrode and stored in the positive electrode during discharging occurs. There is a battery.
Since the lithium secondary battery has high energy density and high output density, it has a large discharge capacity and a high discharge voltage.

A typical secondary battery is a positive electrode and a negative electrode having an active material layer containing an electrode active material formed on the surface of a current collector made of a metal plate, a battery container accommodating the positive electrode and the negative electrode inside, and an electrolytic cell. It is composed of liquid and. Such a secondary battery is manufactured by forming an electrode body composed of a positive electrode and a negative electrode, and injecting an electrolytic solution into the battery container with the electrode body arranged inside the battery container.

Further, the battery manufactured by the above-mentioned manufacturing method is subjected to an aging treatment for holding for several hours to several days after the electrolytic solution is injected, so that the electrolytic solution and the electrode are made compatible with each other. ing.

Further, in secondary batteries, further improvement in battery characteristics is required.

[0007] Here, after further studying the improvement of the battery characteristics, in the above-mentioned method for manufacturing a secondary battery, when the electrolytic solution is injected into the battery container, the current collector of the electrode is in the electrolytic solution. It has been found that there is a problem that the self-discharge performance is degraded due to the elution to the above.

For example, in a lithium secondary battery,
The potential when the negative electrode was immersed in the electrolytic solution was 3.3 V (vs.
Li ⁺ ), and the elution potential of copper used as a normal negative electrode current collector is about 2.5 V, so that Cu of the negative electrode current collector will be eluted into the electrolytic solution. Cu eluted in the electrolytic solution not only causes an increase in internal resistance of the battery, but also causes a slight short circuit between the positive and negative electrodes. In addition, Cu used in a usual negative electrode current collector contains iron (Fe) as an impurity, and Cu is eluted into the electrolytic solution and at the same time Fe is eluted, and this Fe is a lithium secondary battery. The self-discharge performance of is deteriorated.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery manufacturing method and a battery in which elution from a current collector into an electrolytic solution is suppressed. .

[0010]

[Means for Solving the Problems] In order to solve the above problems, as a result of repeated studies on the elution of the current collector, when the electrolytic solution was injected, the electrolytic solution was formed with a potential difference between the positive and negative electrodes. It was found that the above problems can be solved by injecting.

That is, the battery manufacturing method of the present invention comprises a positive electrode having a positive electrode current collector made of metal and a positive electrode active material layer having a positive electrode active material formed on the surface of the positive electrode current collector, and a metal. A negative electrode current collector consisting of, and a negative electrode having a negative electrode active material layer having a negative electrode active material formed on the surface of the negative electrode current collector, and in a state where an electrode body composed of is arranged in a battery container,
A method of manufacturing a battery having an electrolytic solution injecting step of injecting an electrolytic solution into a battery container, wherein the electrolytic solution injecting step comprises injecting the electrolytic solution with a potential applied between a positive electrode and a negative electrode. Characterize.

In the method for producing a battery of the present invention, the potential of the positive electrode and the negative electrode is set to be equal to or lower than the elution potential of the positive electrode current collector and the negative electrode current collector by applying a potential between the positive electrode and the negative electrode in the electrolyte injection step. Therefore, each current collector is no longer eluted in the electrolytic solution. As a result, the battery manufactured by the battery manufacturing method of the present invention is a battery in which deterioration of self-discharge performance is suppressed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION (Battery Manufacturing Method) The battery manufacturing method of the present invention includes an electrolytic solution injecting step.

The electrolyte injection step comprises a positive electrode having a positive electrode current collector made of metal and a positive electrode active material layer having a positive electrode active material formed on the surface of the positive electrode current collector, and a negative electrode current collector made of metal. A negative electrode having a negative electrode having a negative electrode active material layer having a negative electrode active material formed on the surface of the negative electrode current collector, and an electrolytic solution is placed in the battery container in a state where the electrode body is placed in the battery container. This is the step of injecting. That is, by injecting the electrolytic solution in a state where the electrode body is arranged in the battery container, not only the electrolytic solution easily fits in the positive and negative electrodes but also it is possible to prevent the electrolytic solution from becoming an excessive amount. . Specifically, this is because even if a predetermined amount of electrolytic solution is injected into the battery container in advance and the electrode body is immersed in this electrolytic solution, the electrolytic solution cannot contact the surfaces of the positive and negative electrodes.

In the electrolytic solution injecting step, the electrolytic solution is injected with a potential applied between the positive electrode and the negative electrode. That is, by injecting the electrolytic solution in a state in which a potential is applied between the positive electrode and the negative electrode, the potential of the positive electrode and the negative electrode becomes equal to or lower than the elution potential of the positive electrode current collector and the negative electrode current collector, and each current collector is No longer elutes in the electrolyte.

The potential is preferably applied such that the negative electrode is at or below the elution potential of the negative electrode current collector. The negative electrode current collector is prevented from eluting into the electrolytic solution by applying a potential at which the negative electrode is lower than the elution potential of the negative electrode current collector. The material of the negative electrode current collector is selected in consideration of the fact that it is used at a low potential in the manufactured battery, so that the elution potential of the negative electrode current collector is lower than that of the positive electrode current collector. The negative electrode current collector is easily eluted when the electrolytic solution is injected.

It is preferable that the potential is applied between the positive electrode and the negative electrode by performing a charging process. That is,
By performing the charging treatment, the potential of the negative electrode becomes equal to or lower than the elution potential of the negative electrode current collector. Here, the charging process refers to a current-carrying process that is performed during charging in a normal secondary battery, and is a reaction in which the positive salt occludes the ions of the supporting salt in the electrolytic solution and the negative electrode releases the ions into the electrolytic solution. Cause

The method for producing the battery of the present invention is not particularly limited except for the electrolytic solution injecting step. That is, the electrode body, the battery container and the electrolytic solution are not limited.

The electrode body includes a positive electrode current collector made of metal, a positive electrode active material layer having a positive electrode active material formed on the surface of the positive electrode current collector, and a negative electrode current collector made of metal. The material and manufacturing method are not limited as long as it is an electrode body including a negative electrode having a negative electrode active material layer having a negative electrode active material formed on the surface of the negative electrode current collector.

As a method for producing the positive electrode or the negative electrode, for example, an active material paste in which an electrode active material is dispersed is prepared, and the prepared active material paste is applied to the surface of a current collector and dried to form an electrode. An electrode having the electrode active material layer formed on the surface of the current collector is manufactured. Further, it is preferable that the electrode active material layer is compressed by pressing to increase the electrode density.

The battery container is preferably a container capable of holding the electrolytic solution without leaking when the electrolytic solution is injected with the electrode body placed inside. That is, it is preferable that the battery container is composed of a tank-shaped portion into which the electrode body is inserted and held, and a lid portion.

The battery manufactured by the battery manufacturing method of the present invention is preferably a lithium secondary battery. The lithium secondary battery has a positive electrode and a negative electrode capable of inserting and extracting lithium, and a non-aqueous electrolytic solution prepared by dissolving an electrolyte salt in a non-aqueous solvent.

The positive electrode is not particularly limited in its material structure as long as it can release lithium ions during charging and can occlude during discharging, and known materials can be used. In particular, a positive electrode in which a positive electrode active material layer obtained by mixing a positive electrode active material, a conductive material and a binder is applied to a positive electrode current collector can be used.

The positive electrode active material is not particularly limited by the kind of the active material, and a known active material can be used. For example, TiS ₂ , TiS ₃ , MoS ₃ , Fe
S ₂ , Li _(1-x) MnO ₂ , Li _(1-x) Mn ₂ O ₄ , Li
Compounds such as _(1-x) CoO ₂ , Li _(1-x) NiO ₂ and V ₂ O ₅ can be mentioned. Here, x represents 0 to 1. Moreover, you may use the mixture of these compounds as a positive electrode active material. Further, Li _1-x Mn _{2 + x} O ₄ , LiNi _1-x Co
_A positive electrode active material may be obtained by replacing at least one transition metal element of LiMn ₂ O ₄ or LiNiO ₂ with at least one other transition metal element such as _x O ₂ or Li.

As the positive electrode active material, LiMn ₂ O ₄ , Li
A composite oxide of lithium and a transition metal such as CoO ₂ or LiNiO ₂ is more preferable. That is, since it has excellent performance as an active material such as excellent diffusion performance of electrons and lithium ions, a battery having high charge / discharge efficiency and good cycle characteristics can be obtained. Further, as the positive electrode active material,
LiMn ₂ O ₄ is preferably used because of low material cost.

The binder has a function of binding the active material particles together. As the binder, an organic binder or an inorganic binder can be used, and examples thereof include compounds such as polyvinylidene fluoride (PVDF), polyvinylidene chloride, and polytetrafluoroethylene (PTFE). You can

The conductive agent has a function of ensuring electric conductivity of the positive electrode. Examples of the conductive agent include one or a mixture of two or more carbon substances such as carbon black, acetylene black, and graphite.

As the positive electrode current collector, it is possible to use, for example, a net made of metal such as aluminum or stainless steel, a punched metal, a foam metal or a plate-shaped foil.

The negative electrode is not particularly limited in its material structure as long as it can absorb lithium ions during charging and release lithium ions during discharging, and known materials can be used. In particular, a negative electrode in which a negative electrode active material layer obtained by mixing a negative electrode active material and a binder is applied to a negative electrode current collector can be used.

The negative electrode active material is not particularly limited, and a known active material can be used. For example, carbon materials such as highly crystalline natural graphite and artificial graphite,
Examples thereof include metallic lithium, lithium alloys, metallic materials such as tin compounds, and conductive polymers.

The binder has a function of binding the active material particles. As the binder, an organic binder or an inorganic binder can be used, and examples thereof include compounds such as polyvinylidene fluoride (PVDF), polyvinylidene chloride, and polytetrafluoroethylene (PTFE). You can

As the negative electrode current collector, it is possible to use, for example, a net made of copper, nickel or the like, punched metal, foam metal or a foil processed into a plate shape.

The non-aqueous electrolytic solution may be any electrolytic solution used in ordinary lithium secondary batteries, and is composed of an electrolyte salt and a non-aqueous solvent.

Examples of the electrolyte salt include LiP
F₆, LiBF_Four, LiClO_Four, LiAsF₆, LiC
l, LiBr, LiCF₃SO₃, LiN (CF₃S
O₂)₂, LiC (CF₃SO₂)₃, LiI, LiAlC
l_Four, NaClO_Four, NaBF_Four, Nal, etc.
And especially LiPF₆, LiBF_Four, LiClO_Four,
LiAsF₆Inorganic lithium salts such as LiN (SO₂C_x
F_{2x + 1}) (SO₂C_yF_{2y + 1}) Organic lithium salt represented by
Can be raised. Where x and y are 1 to 4
It represents an integer, and x + y is 3 to 8. Organic richiu
Specifically, LiN (SO₂CF₃)
(SO₂C₂F_Five), LiN (SO₂CF₃) (SO₂C
₃F ₇), LiN (SO₂CF₃) (SO₂C_FourF₉), Li
N (SO₂C₂F_Five) (SO₂C ₂F_Five), LiN (SO₂C₂
F_Five) (SO₂C₃F₇), LiN (SO₂C₂F_Five) (SO₂
C_FourF₉) Etc. Among them, LiN (SO₂C
F₃) (SO₂C_FourF₉), LiN (SO₂C₂F_Five) (SO
₂C₂F_Five) Is used as the electrolyte, it has excellent electrical characteristics.
It is preferable because

The concentration of this electrolyte salt in the electrolytic solution is
Is 0.75 to 1.2 mol / dm ³Dissolved to be
It is preferable that The concentration in the electrolyte is 0.75m
ol / dm³If it is less than, sufficient current density cannot be obtained.
Sometimes 1.2 mol / dm³Viscosity exceeds
This will cause a decrease in the conductivity of the electrolytic solution.
is there.

The organic solvent in which the electrolyte salt is dissolved is not particularly limited as long as it is an organic solvent used for a non-aqueous electrolyte of a usual lithium secondary battery, and examples thereof include carbonate compounds, lactone compounds, ether compounds and sulfolane compounds. , Dioxolane compounds, ketone compounds, nitrile compounds, halogenated hydrocarbon compounds and the like. Specifically, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethylene glycol dimethyl carbonate, propylene glycol dimethyl carbonate, ethylene glycol diethyl carbonate, carbonates such as vinylene carbonate, lactones such as γ-butyl lactone, Ethers such as dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,4-dioxane, sulfolanes such as sulfolane and 3-methylsulfolane, dioxolanes such as 1,3-dioxolane, 4-methyl-2- Ketones such as pentanone, acetonitrile,
Examples thereof include nitriles such as pyropionitrile, valeronitrile and benzonitrile, halogenated hydrocarbons such as 1,2-dichloroethane, and other methyl formate, dimethylformamide, diethylformamide, dimethyl sulfoxide and the like. Further, it may be a mixture thereof.

Among these organic solvents, one or more non-aqueous solvents selected from the group consisting of carbonates,
It is preferable because it has excellent solubility, dielectric constant and viscosity of the electrolyte.

The battery manufactured by the method for manufacturing a battery of the present invention is not particularly limited in shape, and is used as a battery of various shapes such as a sheet type, a coin type, a cylindrical type and a square type. it can. It is preferable that the positive electrode and the negative electrode are formed in a sheet shape, and the battery has a wound electrode body that is wound with a sheet-shaped separator interposed therebetween. Further, the electrode body is more preferably a flat wound electrode body because of its excellent volume efficiency.

In the method for producing a battery of the present invention, since the potential of the positive electrode and the negative electrode becomes less than the elution potential of the positive electrode current collector and the negative electrode current collector by applying the potential between the positive electrode and the negative electrode,
Each current collector is no longer eluting in the electrolyte. As a result,
The battery manufactured by the battery manufacturing method of the present invention is a battery in which the deterioration of self-discharge performance is suppressed.

(Battery) The battery of the present invention comprises a positive electrode having a positive electrode current collector made of metal and a positive electrode active material layer having a positive electrode active material formed on the surface of the positive electrode current collector, and made of a metal. A negative electrode having a negative electrode current collector and a negative electrode having a negative electrode active material layer having a negative electrode active material formed on the surface of the negative electrode current collector, a battery container containing the electrode body, and a battery container An electrolytic solution housed together with an electrode body in the battery, wherein the electrolytic solution is in a state in which the electrode body is arranged in the battery container and a potential is applied between the positive electrode and the negative electrode. It is characterized by being injected into the container.

That is, in the battery of the present invention, the electrolytic solution is injected into the battery container while the electrode body is arranged in the battery container and the potential is applied between the positive electrode and the negative electrode. Therefore, elution of each current collector into the electrolytic solution is suppressed. As a result, the battery of the present invention is a battery in which deterioration of self-discharge characteristics is suppressed.

The battery of the present invention comprises a positive electrode having a positive electrode current collector made of metal and a positive electrode active material layer having a positive electrode active material formed on the surface of the positive electrode current collector, and a negative electrode current collection made of metal. Body, and a negative electrode having a negative electrode active material layer having a negative electrode active material formed on the surface of the negative electrode current collector, a battery container containing the electrode body, and an electrode body in the battery container. And an electrolytic solution accommodated therein.

The electric potential is preferably applied such that the negative electrode is at or below the elution potential of the negative electrode current collector. Since the negative electrode is provided with a potential equal to or lower than the elution potential of the negative electrode current collector, the negative electrode current collector does not elute into the electrolytic solution when the electrolytic solution is injected. In addition, since the material of the negative electrode current collector is selected in consideration of being used at a low potential in the battery, the elution potential of the negative electrode current collector is lower than that of the positive electrode current collector. The negative electrode current collector is likely to elute when is injected.

The application of the potential between the positive electrode and the negative electrode is preferably performed by performing a charging process. That is,
By performing the charging treatment, the potential of the negative electrode becomes equal to or lower than the elution potential of the negative electrode current collector. Here, the charging process refers to a current-carrying process that is performed during charging in a normal secondary battery, and is a reaction in which the positive salt occludes the ions of the supporting salt in the electrolytic solution and the negative electrode releases the ions into the electrolytic solution. Cause

The battery of the present invention comprises a positive electrode having a positive electrode current collector made of metal and a positive electrode active material layer having a positive electrode active material formed on the surface of the positive electrode current collector, and a negative electrode current collector made of metal. Body, and a negative electrode having a negative electrode active material layer having a negative electrode active material formed on the surface of the negative electrode current collector, a battery container containing the electrode body, and an electrode body in the battery container. It is not particularly limited except that the electrolyte solution and the electrolyte solution are stored together.

The electrode body includes a positive electrode current collector made of metal, a positive electrode active material layer having a positive electrode active material formed on the surface of the positive electrode current collector, and a negative electrode current collector made of metal. The material and manufacturing method are not limited as long as it is an electrode body including a negative electrode having a negative electrode active material layer having a negative electrode active material formed on the surface of the negative electrode current collector.

As a method for producing the positive electrode or the negative electrode, for example, an active material paste in which an electrode active material is dispersed is prepared, and the prepared active material paste is applied to the surface of a current collector and dried to form an electrode. An electrode having the electrode active material layer formed on the surface of the current collector is manufactured. Further, it is preferable that the electrode active material layer is compressed by pressing to increase the electrode density.

The battery container is preferably a container capable of holding the electrolytic solution without leaking when the electrolytic solution is injected with the electrode body placed inside. That is, it is preferable that the battery container is composed of a tank-shaped portion into which the electrode body is inserted and held, and a lid portion.

The battery of the present invention is preferably a lithium secondary battery. The lithium secondary battery has a positive electrode and a negative electrode capable of inserting and extracting lithium, and a non-aqueous electrolytic solution prepared by dissolving an electrolyte salt in a non-aqueous solvent.

As the positive electrode, it is preferable to use a positive electrode active material paste obtained by mixing a positive electrode active material, a conductive material and a binder, which is applied to a positive electrode current collector.

The positive electrode active material is not particularly limited by the kind of the active material, and a known active material can be used. For example, TiS ₂ , TiS ₃ , MoS ₃ , Fe
S ₂ , Li _(1-x) MnO ₂ , Li _(1-x) Mn ₂ O ₄ , Li
Compounds such as _(1-x) CoO ₂ , Li _(1-x) NiO ₂ and V ₂ O ₅ can be mentioned. Here, x represents 0 to 1. Moreover, you may use the mixture of these compounds as a positive electrode active material. Further, Li _1-x Mn _{2 + x} O ₄ , LiNi _1-x Co
_A positive electrode active material may be obtained by replacing at least one transition metal element of LiMn ₂ O ₄ or LiNiO ₂ with at least one other transition metal element such as _x O ₂ or Li.

As the positive electrode active material, LiMn ₂ O ₄ , Li
A composite oxide of lithium and a transition metal such as CoO ₂ or LiNiO ₂ is more preferable. That is, since it has excellent performance as an active material such as excellent diffusion performance of electrons and lithium ions, a battery having high charge / discharge efficiency and good cycle characteristics can be obtained. Further, as the positive electrode active material,
LiMn ₂ O ₄ is preferably used because of low material cost.

The binder has a function of binding the active material particles. As the binder, an organic binder or an inorganic binder can be used, and examples thereof include compounds such as polyvinylidene fluoride (PVDF), polyvinylidene chloride, and polytetrafluoroethylene (PTFE). You can

The conductive agent has a function of ensuring the electrical conductivity of the positive electrode. Examples of the conductive agent include one or a mixture of two or more carbon substances such as carbon black, acetylene black, and graphite.

As the positive electrode current collector, it is possible to use, for example, a net made of metal such as aluminum or stainless steel, a punched metal, a foam metal, or a foil processed into a plate shape.

As the negative electrode, it is preferable to use a negative electrode current collector in which a negative electrode active material paste obtained by mixing a negative electrode active material and a binder is applied.

The negative electrode active material is not particularly limited, and a known active material can be used. For example, carbon materials such as highly crystalline natural graphite and artificial graphite,
Examples thereof include metallic lithium, lithium alloys, metallic materials such as tin compounds, and conductive polymers.

The binder has a function of binding the active material particles together. As the binder, an organic binder or an inorganic binder can be used, and examples thereof include compounds such as polyvinylidene fluoride (PVDF), polyvinylidene chloride, and polytetrafluoroethylene (PTFE). You can

As the negative electrode current collector, it is possible to use, for example, a net made of copper or nickel, a punched metal, a foam metal or a foil processed into a plate shape.

The non-aqueous electrolytic solution may be any electrolytic solution used in ordinary lithium secondary batteries, and is composed of an electrolyte salt and a non-aqueous solvent.

Examples of the electrolyte salt include LiP
F₆, LiBF_Four, LiClO_Four, LiAsF₆, LiC
l, LiBr, LiCF₃SO₃, LiN (CF₃S
O₂)₂, LiC (CF₃SO₂)₃, LiI, LiAlC
l_Four, NaClO_Four, NaBF_Four, Nal, etc.
And especially LiPF₆, LiBF_Four, LiClO_Four,
LiAsF₆Inorganic lithium salts such as LiN (SO₂C_x
F_{2x + 1}) (SO₂C_yF_{2y + 1}) Organic lithium salt represented by
Can be raised. Where x and y are 1 to 4
It represents an integer, and x + y is 3 to 8. Organic richiu
Specifically, LiN (SO₂CF₃)
(SO₂C₂F_Five), LiN (SO₂CF₃) (SO₂C
₃F ₇), LiN (SO₂CF₃) (SO₂C_FourF₉), Li
N (SO₂C₂F_Five) (SO₂C ₂F_Five), LiN (SO₂C₂
F_Five) (SO₂C₃F₇), LiN (SO₂C₂F_Five) (SO₂
C_FourF₉) Etc. Among them, LiN (SO₂C
F₃) (SO₂C_FourF₉), LiN (SO₂C₂F_Five) (SO
₂C₂F_Five) Is used as the electrolyte, it has excellent electrical characteristics.
It is preferable because

The concentration of this electrolyte salt in the electrolytic solution is
Is 0.75 to 1.2 mol / dm ³Dissolved to be
It is preferable that The concentration in the electrolyte is 0.75m
ol / dm³If it is less than, sufficient current density cannot be obtained.
Sometimes 1.2 mol / dm³Viscosity exceeds
This will cause a decrease in the conductivity of the electrolytic solution.
is there.

The organic solvent in which the electrolyte salt is dissolved is not particularly limited as long as it is an organic solvent used for a non-aqueous electrolyte of a usual lithium secondary battery, and examples thereof include carbonate compounds, lactone compounds, ether compounds and sulfolane compounds. , Dioxolane compounds, ketone compounds, nitrile compounds, halogenated hydrocarbon compounds and the like. Specifically, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethylene glycol dimethyl carbonate, propylene glycol dimethyl carbonate, ethylene glycol diethyl carbonate, carbonates such as vinylene carbonate, lactones such as γ-butyl lactone, Ethers such as dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,4-dioxane, sulfolanes such as sulfolane and 3-methylsulfolane, dioxolanes such as 1,3-dioxolane, 4-methyl-2- Ketones such as pentanone, acetonitrile,
Examples thereof include nitriles such as pyropionitrile, valeronitrile and benzonitrile, halogenated hydrocarbons such as 1,2-dichloroethane, and other methyl formate, dimethylformamide, diethylformamide, dimethyl sulfoxide and the like. Further, it may be a mixture thereof.

Among these organic solvents, one or more non-aqueous solvents selected from the group consisting of carbonates,
It is preferable because it has excellent solubility, dielectric constant and viscosity of the electrolyte.

The shape of the battery of the present invention is not particularly limited, and it can be used as a battery of various shapes such as a sheet type, a coin type, a cylindrical type and a square type. It is preferable that the positive electrode and the negative electrode are formed in a sheet shape, and the battery has a wound electrode body that is wound with a sheet-shaped separator interposed therebetween. Further, the electrode body is more preferably a flat wound electrode body because of its excellent volume efficiency.

In the battery of the present invention, by applying a potential between the positive electrode and the negative electrode, the potential of the positive electrode and the negative electrode becomes equal to or lower than the elution potential of the positive electrode current collector and the negative electrode current collector. It no longer dissolves in the electrolyte. As a result, the battery of the present invention is a battery in which deterioration of self-discharge performance is suppressed.

[0067]

The function of the battery manufacturing method of the present invention will be described in detail using a lithium battery. Here, the lithium secondary battery used for the description is a conventional lithium secondary battery, specifically, the lithium secondary battery manufactured in the comparative example.

In the lithium secondary battery, when the metal Li is considered as the reference potential, the potential difference between the positive electrode and the negative electrode is the battery voltage. However, in the lithium secondary battery, the potential is not applied to the positive electrode and the negative electrode in the state where the initial charge / discharge process is not performed, and thus the positive electrode and the negative electrode have a potential of about 3.5V. After that, an initial charge / discharge process is performed to apply a potential to the positive and negative electrodes, and the potential difference between the positive and negative electrodes becomes the battery voltage. Here, changes in the potentials of the positive electrode and the negative electrode of the lithium secondary battery are shown in FIG.

Subsequently, the potential and current of Cu in the electrolytic solution used as the negative electrode current collector were measured and shown in FIG.

From FIG. 2, the potential is approximately 2.5 V (vs.
It can be seen that the current increases when the temperature exceeds Li ⁺ ). This indicates that Cu is eluted in the electrolytic solution when the potential exceeds 2.5 V (vs. Li ⁺ ).

That is, in the initial stage of the battery shown in FIG. 1, the potential of the negative electrode is about 3.5 V, so that elution occurs in the electrolytic solution.

On the other hand, in the production method of the present invention, since the electric potential is applied to the electrode body during the injection of the electrolytic solution, the electric potential of the negative electrode is promptly lowered to the elution potential of the negative electrode current collector or less. be able to. As a result, in the battery manufacturing method of the present invention, the occurrence of defects caused by the negative electrode current collector being eluted into the electrolytic solution is suppressed.

[0073]

EXAMPLES The present invention will be described below with reference to examples. (Example) As an example of the present invention, a lithium secondary battery was manufactured.

(Method for manufacturing lithium secondary battery) First, L
85 parts by weight of a positive electrode active material composed of iNiO _2, 10 parts by weight of carbon as a conductive agent, and 5 parts by weight of polyvinylidene fluoride (PVDF) as a binder were mixed with N-methyl-.
It was dissolved in a 2-pyrrolidone (NMP) solution to prepare a positive electrode active material paste. This paste was applied to both sides of a positive electrode current collector made of aluminum foil with a comma coater.

Next, this electrode was passed through a roll press to apply a load to prepare a positive electrode plate having an improved electrode density.
Then, this positive electrode plate was cut into a predetermined size, and the sheet-shaped positive electrode was manufactured by scraping off the electrode mixture in the portion that will become the lead tab weld for current extraction.

Subsequently, 92 parts by weight of a negative electrode active material made of graphite and 8 parts by weight of PVDF as a binder were dissolved in an NMP solution to prepare a negative electrode active material paste. This paste was applied to both surfaces of a negative electrode current collector made of copper foil using a comma coater as in the positive electrode. afterwards,
The copper foil coated with this paste was passed through a roll press to apply a load, and a negative electrode plate having an increased electrode density was produced.

Next, this negative electrode plate was cut into a predetermined size, and the sheet-shaped negative electrode was manufactured by scraping off the electrode mixture in the portion which will become the lead tab weld for current extraction.

The sheet-shaped positive electrode and the sheet-shaped negative electrode obtained above were wound with a separator made of microporous polypropylene having a thickness of 25 μm interposed therebetween to form a wound electrode body.

Further, LiPF ₆ which is an electrolyte is mixed with ethylene carbonate (EC) and diethyl carbonate (DE
An electrolytic solution was prepared by dissolving 1) C and 1) in a solvent mixed at an equal volume ratio at a ratio of 1 mol / liter.

Subsequently, the spirally wound electrode body was inserted and held inside a cylindrical case. At this time, the current collecting lead having one end welded to the lead tab weld portion of the sheet-shaped positive electrode and the sheet-shaped negative electrode was joined to the positive electrode terminal or the negative electrode terminal of the case.

Then, the electrolytic solution was injected into the case holding the spirally wound electrode body, and the case was hermetically sealed.
At this time, the electrolytic solution was injected while applying a potential so that a potential difference of 3 V was generated between the positive and negative electrodes. At this time,
The potential of the positive electrode was 3.7 V (vs. Li ⁺ ) and the potential of the negative electrode was 0.7 V (vs. Li ⁺ ). The method of applying a potential between the positive and negative electrodes was performed by electrically connecting the positive electrode of the electrode body to the negative electrode of the external power source and the negative electrode of the electrode body to the positive electrode of the external power source, and energizing.

By the above procedure, the cylindrical lithium secondary battery of Example having φ18 mm and the axial length of 65 mm was manufactured.

Comparative Example As a comparative example, a battery was manufactured in the same manner as in the example except that the electrolytic solution was injected without applying a potential between the positive and negative electrodes.

(Evaluation) As the evaluation of the batteries of Examples and Comparative Examples, changes in internal resistance and discharge capacity of the batteries were measured.

Specifically, the initial internal resistance and discharge capacity of the batteries of Examples and Comparative Examples were measured, and the discharge capacity after leaving this battery for 1 month was measured, and the residual capacity was calculated from the ratio of the discharge capacities. It was measured.

Internal resistance measurements were made by measuring the resistance at 1V. In addition, the measurement of discharge capacity is
CC discharge from 4.1V to 3.0V at 1 / 3C,
This was done by measuring the battery capacity at this time.
The measurement results are shown in Table 1.

[0087]

[Table 1]

From Table 1, the battery of the comparative example has an internal resistance of 50.
mΩ, and the internal resistance of the battery of the example was 47 mΩ. That is, the batteries of Examples had a low initial internal resistance.

The battery of the comparative example had a low remaining capacity of 90%, but the battery of the example had a remaining capacity of 97%, showing almost no decrease in the capacity.

That is, in the battery of the embodiment, the potential of the negative electrode is 0.7 V, which is lower than the elution potential of Cu, 2.5 V, by applying the potential between the positive and negative electrodes during the injection of the electrolytic solution. The negative electrode current collector is no longer dissolved in the electrolyte. As a result, in the batteries of the examples, since Cu ions eluted from the negative electrode current collector do not exist in the electrolytic solution, increase in internal resistance and decrease in discharge capacity due to the Cu ions are suppressed.

On the other hand, in the battery of the comparative example, when the electrolytic solution was poured, Cu ions were eluted from the negative electrode current collector into the electrolytic solution, and the Cu ions increased the internal resistance of the battery.

From the above, in the lithium secondary battery of the example, a decrease in battery amount is suppressed by applying a potential between the positive and negative electrodes when injecting the electrolytic solution.

[0093]

EFFECTS OF THE INVENTION In the method for producing a battery of the present invention, the potentials of the positive electrode and the negative electrode are changed by applying a potential between the positive electrode and the negative electrode in the electrolytic solution injecting step. Because of the following, each current collector is no longer eluted in the electrolytic solution. As a result, the battery manufactured by the battery manufacturing method of the present invention is a battery in which deterioration of self-discharge performance is suppressed.

[Brief description of drawings]

FIG. 1 is a diagram showing the results of measuring the potentials of a positive electrode and a negative electrode during injection of an electrolytic solution of a battery of a comparative example.

FIG. 2 is a diagram showing the relationship between the electric potential of Cu in a non-aqueous electrolyte and the current.

Claims (6)

[Claims] 1. A positive electrode having a positive electrode current collector made of metal and a positive electrode active material layer having a positive electrode active material formed on the surface of the positive electrode current collector; a negative electrode current collector made of metal; Injecting an electrolytic solution into a battery container with an electrode body composed of a negative electrode having a negative electrode active material layer having a negative electrode active material formed on the surface of the negative electrode current collector and arranged in the battery container. A method of manufacturing a battery having an electrolytic solution injecting step, wherein the electrolytic solution injecting step is performed by injecting the electrolytic solution in a state in which a potential is applied between the positive electrode and the negative electrode. Manufacturing method. 2. The potential is applied so that the negative electrode has a potential equal to or lower than the elution potential of the negative electrode current collector.
A method for manufacturing the battery described above. 3. The method for producing a battery according to claim 1, which is a lithium secondary battery. 4. A positive electrode having a positive electrode current collector made of metal and a positive electrode active material layer having a positive electrode active material formed on the surface of the positive electrode current collector; a negative electrode current collector made of metal; An electrode body comprising a negative electrode having a negative electrode active material layer having a negative electrode active material formed on the surface of the negative electrode current collector, a battery container containing the electrode body, and the electrode in the battery container. An electrolytic solution housed with the body,
A battery having the following: the electrolytic solution is injected into the battery container in a state where the electrode body is arranged in the battery container and a potential is applied between the positive electrode and the negative electrode. A battery characterized by that. 5. The potential is applied so that the negative electrode has a potential equal to or lower than the elution potential of the negative electrode current collector.
Battery described. 6. The battery according to claim 4, which is a lithium secondary battery.