JPH11273680A - Manufacturing method of secondary battery - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent electrode material from falling off from an electrode current collector,
Improves charge-discharge cycle characteristics and life characteristics. SOLUTION: On at least one main surface of a positive electrode current collector, a positive electrode mixture layer composed of at least a positive electrode material and a binder is applied to form a positive electrode, and the positive electrode mixture layer is formed on at least one main surface of the negative electrode current collector. Then, a negative electrode mixture layer composed of at least a negative electrode material and a binder is applied to form a negative electrode. And at this time,
Perhydropolysilazane is contained in the positive electrode mixture and / or the negative electrode mixture, and after applying the electrode mixture containing the perhydropolysilazane, a heat treatment is performed to perform composite coating of the perhydropolysilazane and the binder. Form a film. Further, the positive electrode and the negative electrode are opposed to each other via an electrolyte phase to form a secondary battery. The content of the perhydropolysilazane is preferably 0.5 to 30 parts by weight based on 100 parts by weight of the binder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a secondary battery. More specifically, the present invention relates to a method for manufacturing a secondary battery in which a positive electrode and / or a negative electrode expand and contract with charge and discharge.

[0002]

2. Description of the Related Art Conventionally, nickel-cadmium batteries and lead batteries have been used as secondary batteries for electronic equipment. However, in recent years, with the advancement of electronic technology, the performance, size, and portability of electronic devices have advanced, and the demand for higher energy density of secondary batteries for electronic devices has increased. In a cadmium battery, a lead battery, and the like, there has been a problem that the discharge voltage is low and the energy density cannot be sufficiently increased.

Therefore, a secondary battery having a high discharge voltage, a small self-discharge, and a long cycle life has recently been developed.
Instead of nickel-cadmium batteries or lead batteries, the anode uses a material that can store and release lithium ions, such as carbon materials such as coke and graphite,
Secondary batteries using lithium composite oxides such as lithium cobalt composite oxide for the positive electrode have been actively researched and developed.

[0004] As an electrolyte for such a secondary battery, propylene carbonate, ethylene carbonate, γ-
A solvent such as butyrolactone, tetrahydrofuran, or sulfolane is used alone or as a mixed solvent, and LiClO ₄ , LiAsF ₆ , LiBF ₄ , and CF ₃ SO are used as electrolytes.
₃ which was used as _{Li ,, LiPF 6, LiN (CF} 3 SO 2) alone or a mixture of a lithium salt such as ₂ are used.

In such a secondary battery, a microporous film of polyethylene, polypropylene, polytetrafluoroethylene or the like is used as a separator for preventing a short circuit between the positive and negative electrodes.

A method for manufacturing such a secondary battery includes the following method. That is, first, a fluorine-based polymer material such as a vinyl fluoride resin or a vinylidene fluoride resin that functions as an ion conductor as a binder is prepared. Next, this is dissolved in an organic solvent, and a positive electrode material or a negative electrode material is dispersed therein to produce a positive electrode mixture or a negative electrode mixture. Next, the positive electrode mixture or the negative electrode mixture is coated on a positive electrode current collector or a negative electrode current collector, and dried to form a positive electrode mixture layer or a negative electrode mixture layer, thereby manufacturing a positive electrode or a negative electrode. Then, the positive electrode and the negative electrode are opposed to each other with the above-described electrolytic solution phase interposed therebetween to complete a secondary battery.

[0007]

However, the fluoropolymers such as vinyl fluoride resin and vinylidene fluoride resin used as the binder partially swell in an electrolyte containing a polar solvent. Or dissolve. For this reason, after the secondary battery is manufactured as described above, the binder component moves into the electrolytic solution, the electrode material (active material) drops off from the electrode current collector surface, and the charge / discharge cycle occurs. Characteristics and life characteristics may be impaired.

In particular, an electrode material (active material) that utilizes intercalation and deintercalation reactions of lithium ions with charge and discharge as the electrode material (active material) undergoes expansion and contraction accompanying the reaction. Accordingly, the electrode mixture layer containing the electrode material (active material) is easily peeled off from the electrode current collector surface, and the charge-discharge cycle characteristics and the life characteristics are easily impaired.

In order to prevent the electrode material (active material) from falling off the surface of the electrode current collector, a primer resin for improving the adhesive force of the electrode mixture layer to the surface of the electrode current collector is used in combination. ing. Examples of the primer resin include an acrylic modified resin, polyamide, polyimide, a coupling agent and the like. However, many of these primer resins have poor compatibility with fluoropolymers such as vinyl fluoride resin and vinylidene fluoride resin. ~ 4.
An oxidation-reduction reaction at 5 (V) occurs, which is a factor that lowers battery characteristics.

Accordingly, the present invention has been proposed in view of the above-described circumstances, and it is intended to prevent the electrode material from falling off from the electrode current collector and to improve the charge / discharge cycle characteristics and life characteristics. It is intended to provide a method for manufacturing a secondary battery.

[0011]

Means for Solving the Problems As a result of intensive studies by the present inventors to achieve the above object, perhydropolysilazane which is an inorganic polymer is converted into a fluoropolymer such as a vinyl fluoride resin or a vinylidene fluoride resin. If a heat treatment is performed after applying the electrode mixture using these to the electrode current collector, a composite coating film of perhydropolysilazane and the binder is formed, and the electrode material It has been found that it is possible to manufacture a secondary battery in which the electrode is prevented from falling off from the electrode current collector and the cycle characteristics of charge and discharge and the life characteristics are improved.

[0012] Further, by heating the perhydropolysilazane in this manner, silica is formed, whereby the compatibility with fluoropolymers such as vinyl fluoride resin and vinylidene fluoride resin is further improved, and electrochemically. It has also been found that this also makes it possible to prevent the electrode material from falling off from the electrode current collector and to manufacture a secondary battery having improved charge / discharge cycle characteristics and life characteristics.

That is, in the method of manufacturing a secondary battery according to the present invention, a positive electrode mixture comprising at least a positive electrode material and a binder is applied on at least one main surface of a positive electrode current collector to form a positive electrode mixture layer. A negative electrode mixture formed by applying a negative electrode mixture comprising at least a negative electrode material and a binder on at least one main surface of the negative electrode current collector to form a negative electrode, and forming a negative electrode. And a negative electrode facing each other via an electrolyte phase to form a secondary battery, wherein a perhydropolysilazane is contained in the positive electrode mixture and / or the negative electrode mixture, and the positive electrode mixture containing the perhydropolysilazane is contained. After applying the agent and / or the negative electrode mixture, a heat treatment is performed to form a composite coating film of the perhydropolysilazane and the binder.

The above-mentioned perhydropolysilazane is synthesized by a general method, and is synthesized with ammonium chloride as a by-product when it is reacted with ammonia in the presence of dichlorosilane and pyridine (ammonolysis reaction). The molecular weight is preferably from 600 to 5,000. When the molecular weight is larger than 5,000, the organic solubility is reduced and the gel is easily formed, and the workability is reduced. In addition, the molecular weight is 600
If it is smaller than that, the conversion reaction to silica becomes slower and the required heating temperature becomes higher, the workability decreases, and the electrode current collector needs to be made of a limited material.

As a specific method of the heat treatment after the application of the positive electrode mixture and / or the negative electrode mixture containing perhydropolysilazane, a hot air heating drying method and a far infrared heating drying method may be mentioned. At this time, the heating temperature is 100 to 20
It is preferably set to 0 (° C.). If it is less than 100 (° C.), the conversion reaction to silica may be insufficient, the reaction time is long, and the workability is not good. On the other hand, 200
If the temperature is higher than (° C.), the binder such as vinylidene fluoride resin may be thermally decomposed, which is not preferable.

In the method of manufacturing a secondary battery according to the present invention, in the positive electrode mixture and / or the negative electrode mixture containing perhydropolysilazane, the content of the perhydropolysilazane with respect to 100 parts by weight of the binder is used. Is 0.5
To 30 parts by weight, more preferably 1 to 30 parts by weight.
To 10 parts by weight.

If the perhydropolysilazane content is less than 0.5 part by weight, sufficient effects cannot be obtained, and
If the amount is more than 0 parts by weight, the flexibility of the electrode mixture layer is impaired, and when the wound electrode body is formed, the electrode mixture layer is cracked or the like, and the characteristics of the battery are impaired.

In the method of manufacturing a secondary battery according to the present invention, the negative electrode material is a material containing a carbon material which can be doped and dedoped with lithium, and the positive electrode material contains a transition metal composite oxide containing lithium. Preferably, it is a material.

In the method for manufacturing a secondary battery according to the present invention,
Perhydropolysilazane was contained in the positive electrode mixture and / or the negative electrode mixture, and the positive electrode mixture and / or the negative electrode mixture containing the perhydropolysilazane was applied on the positive electrode current collector and / or the negative electrode current collector. Thereafter, by performing a heat treatment to form a composite coating film of the above-mentioned perhydropolysilazane and the binder, from the electrode current collector of the electrode material in the electrode mixture containing the above-mentioned perhydropolysilazane Shedding is prevented.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

That is, in the method of manufacturing a secondary battery according to the present invention, a positive electrode mixture comprising at least a positive electrode material and a binder is applied on at least one principal surface of a positive electrode current collector. Forming a layer to form a positive electrode, on at least one main surface of the negative electrode current collector, apply a negative electrode mixture comprising at least a negative electrode material and a binder to form a negative electrode mixture layer,
A negative electrode.

At this time, in particular, a perhydropolysilazane is contained in the positive electrode mixture and / or the negative electrode mixture, and after applying the positive electrode mixture and / or the negative electrode mixture containing the perhydropolysilazane, the mixture is heated. The treatment is performed to form a composite coating film of the above-mentioned perhydropolysilazane and the binder.

Further, the positive electrode and the negative electrode are opposed to each other via an electrolyte phase to form a secondary battery.

The above perhydropolysilazane (PERHY)
DROPOLYSILAZANE is synthesized by a general method, and as shown in the following chemical formula 1, dichlorosilane (SiH ₂ Cl ₂ ) and pyridine (Pyridin).
It is synthesized together with ammonia (NH ₃ ) in the presence of e) (ammonolysis reaction) together with ammonium chloride as a by-product.

[0025]

Embedded image

The molecular weight is preferably from 600 to 5,000. When the molecular weight is larger than 5,000, the organic solubility is reduced and the gel is easily formed, and the workability is reduced. On the other hand, if the molecular weight is smaller than 600, the conversion reaction to silica becomes slow and the required heating temperature increases, the workability decreases, and it is necessary to use a limited material for the electrode current collector. Occurs.

The above perhydropolysilazane (PERHY)
As a specific method of the heat treatment after applying the positive electrode mixture and / or the negative electrode mixture containing (DROPOLYSILAZANE), a hot-air heating drying method and a far-infrared heating drying method may be mentioned. That is, as shown in Chemical formula 1, perhydropolysilazane (PERHYDROPOLYSIL)
When AZONE is heated in air (Air (O ₂ , H ₂ O)), silica (SILICA) is formed.

At this time, the heating temperature is 100 to 200.
(° C.). If it is less than 100 (° C.), the conversion reaction to silica may be insufficient, the reaction time is long, and the workability is not good. On the other hand, 200
If the temperature is higher than (° C.), the binder such as vinylidene fluoride resin may be thermally decomposed, which is not preferable.

In the method of manufacturing a secondary battery according to the present invention, in the positive electrode mixture and / or the negative electrode mixture containing perhydropolysilazane, the content of the perhydropolysilazane with respect to 100 parts by weight of the binder is used. Is 0.5
To 30 parts by weight, more preferably 1 to 30 parts by weight.
To 10 parts by weight.

If the perhydropolysilazane content is less than 0.5 parts by weight, sufficient effects cannot be obtained, and
If the amount is more than 0 parts by weight, the flexibility of the electrode mixture layer is impaired, and when the wound electrode body is formed, the electrode mixture layer is cracked or the like, and the characteristics of the battery are impaired.

In order to add perhydropolysilazane to the positive electrode mixture and / or the negative electrode mixture as described above, the above-mentioned perhydropolysilazane is dissolved in a solvent containing no OH group, such as xylene or toluene. 50 (% by weight)
It is only necessary to dissolve and add in the ratio of. In addition,
Considering workability and coating thickness, 10 to 20 (% by weight)
It is preferable that

As a binder, a fluorine-based polymer such as a vinyl fluoride resin and a vinylidene fluoride resin generally used in this type of secondary battery is used. Among them, a homopolymer or a copolymer of a vinylidene fluoride resin alone or These mixtures are preferably used.

In the method of manufacturing a secondary battery according to the present invention, a positive electrode mixture and / or a negative electrode containing perhydropolysilazane are used in order to promote a conversion reaction of perhydropolysilazane to silica and to lower a heating temperature. P in the mixture
Basic organic compounds such as t and Pd-based organometallic compounds, pyridine and amines may be added as catalysts.

Further, in the method of manufacturing a secondary battery according to the present invention, the negative electrode material is a material containing a carbon material which can be doped and dedoped with lithium, and the positive electrode material contains a transition metal composite oxide containing lithium. Preferably, it is a material.

Examples of the carbon material mentioned as the negative electrode material include pyrolytic carbons and cokes (pitch coke,
Needle coke, petroleum coke, etc.), graphites, glassy carbons, fired organic polymer compounds (fired phenol resin, furan resin, etc.), carbon fiber, activated carbon, and the like. As the negative electrode material, a crystalline or amorphous metal oxide capable of doping and undoping lithium ions is used in addition to the carbon material.

The cathode material preferably contains sufficient Li, for example, LiMO ₂ (where M is at least one of Co, Ni, Mn, Fe, Al, V and Ti). Preferable examples include a composite metal oxide composed of lithium and a transition metal, and an interlayer compound containing Li.

In such a secondary battery, the electrode mixture layer containing the electrode material easily peels off from the surface of the electrode current collector due to expansion and contraction accompanying the reaction as described above. The application prevents the electrode mixture layer from peeling off from the electrode current collector surface.

Further, the shape of the electrode current collector is as follows.
Although not particularly limited, foil, or mesh,
A net-like material such as expanded metal is used. As a material used for the positive electrode current collector, for example, aluminum, stainless steel, nickel, or the like is preferably used.
As a material used for the negative electrode current collector, for example, copper, stainless steel, nickel, or the like is preferably used.

Further, as a method of forming the positive electrode mixture layer and the negative electrode mixture layer on the positive electrode current collector and the negative electrode current collector, a doctor blade method generally used for manufacturing this type of secondary battery is used. And the like.

In the method for manufacturing a secondary battery according to the present invention,
Perhydropolysilazane was contained in the positive electrode mixture and / or the negative electrode mixture, and the positive electrode mixture and / or the negative electrode mixture containing the perhydropolysilazane was applied on the positive electrode current collector and / or the negative electrode current collector. Thereafter, by performing a heat treatment to form a composite coating film of the above-mentioned perhydropolysilazane and the binder, from the electrode current collector of the electrode material in the electrode mixture containing the above-mentioned perhydropolysilazane It is possible to manufacture a secondary battery in which falling off is prevented and charge / discharge cycle characteristics and life characteristics are improved.

Further, silica is formed by heat-treating perhydropolysilazane in this manner, whereby the compatibility with fluorine-based polymers such as vinyl fluoride resin and vinylidene fluoride resin is further improved, and electrochemically. Therefore, the electrode material in the electrode mixture is prevented from falling off from the electrode current collector, and a secondary battery with improved charge / discharge cycle characteristics and life characteristics can be manufactured.

[0042]

EXAMPLE Next, in order to confirm the effects of the present invention, a secondary battery was actually manufactured and its characteristics were evaluated.

Preparation of Sample (Sample 1) <Preparation of Positive Electrode> First, a positive electrode was prepared. LiCoO ₂ powder 91 (parts by weight) as a positive electrode active material and graphite 6 (parts by weight) as a conductive agent were mixed. To a vinylidene fluoride resin 100 (parts by weight) as a binder, 10 (parts by weight) of a perhydropolysilazane solution having a concentration of 10 (% by weight) using toluene as a solvent was added and mixed, and this was added to an N-methylpyrrolidone solvent. By dissolving, a solution having a content of vinylidene fluoride resin / perhydropolysilazane of 5 (% by weight) was prepared. Then, a slurry was prepared as a positive electrode mixture such that the weight ratio of the mixture of LiCoO ₂ powder and graphite and vinylidene fluoride resin / perhydropolysilazane was 95: 5. That is, here, the amount of perhydropolysilazane added to 100 parts by weight of vinylidene fluoride resin as a binder is 1 (parts by weight).

Next, the slurry as the positive electrode mixture was applied to both surfaces of an aluminum foil as a positive electrode current collector by a doctor blade method to form a positive electrode mixture layer. Finally 150
(° C.) The heat treatment of the positive electrode mixture layer is performed under the conditions of 2 (hr), the solvent is volatilized, and the perhydropolysilazane in the positive electrode mixture layer is converted into silica. Was formed to form a composite coating film of vinylidene fluoride resin, thereby completing a positive electrode.

<Preparation of Negative Electrode> 100% by weight of vinylidene fluoride resin as a binder was dissolved in an N-methylpyrrolidone solvent to prepare a solution containing 5% by weight of vinylidene fluoride resin. . Then, graphite was added to this solution so that the weight ratio of graphite to vinylidene fluoride resin was 95: 5, and a slurry was prepared as a negative electrode mixture. Next, the slurry as the negative electrode mixture was applied to both surfaces of a copper foil as a negative electrode current collector by a doctor blade method to form a negative electrode mixture layer. Finally, the negative electrode mixture layer was subjected to heat treatment under the conditions of 150 (° C.) and 2 (hr), and the solvent was volatilized to complete the negative electrode.

<Preparation of Electrolytic Solution> Propylene carbonate (PC) 50 (parts by weight) and dimethyl carbonate (DMC) 5
0 (parts by weight) and 1 (mol) of LiPF ₆ as an electrolyte
/ Cm ³ ) to obtain an electrolytic solution.

<Assembly of Battery> A battery was assembled using the positive electrode, the negative electrode, and the electrolytic solution thus obtained. That is, a microporous polypropylene film having a thickness of 25 (μm) was used as a separator, and a negative electrode and a positive electrode were laminated with the separator interposed therebetween and then wound many times to form a wound electrode body.

The wound electrode body was housed in a nickel-plated iron battery can. Furthermore, insulating plates are arranged on both the upper and lower surfaces of the wound electrode body, and the aluminum positive electrode lead is led out from the positive electrode current collector to the positive electrode, and the nickel negative electrode lead is drawn out from the negative electrode current collector to the battery can. Connected.

In this battery, a current interrupting thin plate was provided as a safety device, and the positive electrode was attached to the current interrupting thin plate.

Subsequently, the electrolyte was injected into the battery can. Next, by caulking the battery can through a sealing gasket that also covers the surface coated with asphalt, the current interrupting thin plate having a current interrupting mechanism and the battery lid are fixed, the airtightness inside the battery is maintained, and the diameter is reduced. 18 (mm),
A cylindrical non-aqueous electrolyte secondary battery having a height of 65 (mm) was obtained.

That is, in this secondary battery, the battery lid is substantially a positive electrode. Note that this secondary battery is referred to as Sample 1.

(Sample 2) <Preparation of Positive Electrode> Here, vinylidene fluoride resin 100 (part by weight) as a binder was mixed with toluene 10 as a solvent.
(Percent by weight) of a perhydropolysilazane solution of 50% by weight.
(Parts by weight) Except for addition and mixing, a positive electrode was prepared in the same manner as in Sample 1. That is, in this case, the amount of perhydropolysilazane added to vinylidene fluoride resin 100 (parts by weight) as a binder is 5 (parts by weight).

<Preparation of Negative Electrode and Electrolyte> A negative electrode and an electrolyte were prepared in the same manner as in Sample 1.

<Assembly of Battery> A battery was assembled in the same manner as in Sample 1 to obtain a cylindrical nonaqueous electrolyte secondary battery. Note that this battery is referred to as Sample 2.

(Sample 3) <Preparation of Positive Electrode> First, a positive electrode was prepared. LiCoO ₂ powder 91 (parts by weight) as a positive electrode active material and graphite 6 (parts by weight) as a conductive agent were mixed. A vinylidene fluoride resin 100 (parts by weight) as a binder was dissolved in an N-methylpyrrolidone solvent to prepare a solution having a vinylidene fluoride resin content of 5 (% by weight). And L
A slurry was prepared as a positive electrode mixture such that the weight ratio of the mixture of iCoO ₂ powder, graphite, and vinylidene fluoride resin was 95: 5.

Next, the slurry as the positive electrode mixture was applied to both surfaces of an aluminum foil as a positive electrode current collector by a doctor blade method to form a positive electrode mixture layer. Finally 150
The heat treatment of the positive electrode mixture layer was performed under the conditions of (° C.) and 2 (hr) to evaporate the solvent and complete the positive electrode.

<Preparation of Negative Electrode> A vinylidene fluoride resin 100 (part by weight) as a binder was mixed with toluene 1 as a solvent.
0 (wt%) perhydropolysilazane solution
0 (parts by weight) were added and mixed, and this was dissolved in an N-methylpyrrolidone solvent to prepare a solution having a vinylidene fluoride resin / perhydropolysilazane content of 5 (% by weight). Then, graphite and vinylidene fluoride resin /
Graphite was added so that the weight ratio of perhydropolysilazane was 95: 5, and a slurry was prepared as a negative electrode mixture.
That is, here, the amount of perhydropolysilazane added to 100 parts by weight of vinylidene fluoride resin as a binder is 1 (parts by weight).

Next, the slurry as the negative electrode mixture was applied to both surfaces of a copper foil as a negative electrode current collector by a doctor blade method to form a negative electrode mixture layer. Finally 150 (℃), 2
The heat treatment of the negative electrode mixture layer is performed under the condition (hr), the solvent is volatilized, the perhydropolysilazane in the negative electrode mixture layer is converted into silica, and the perhydropolysilazane and vinylidene fluoride as a binder are converted. A negative electrode was completed by forming a resin composite coating film.

<Preparation of Negative Electrode and Electrolyte> A negative electrode and an electrolyte were prepared in the same manner as in Sample 1.

<Assembly of Battery> A battery was assembled in the same manner as in Sample 1 to obtain a cylindrical nonaqueous electrolyte secondary battery. Note that this battery is referred to as Sample 3.

(Sample 4) <Preparation of Negative Electrode> In this example, vinylidene fluoride resin 100 (parts by weight) as a binder was mixed with toluene 10 as a solvent.
(Percent by weight) of a perhydropolysilazane solution of 20%
(Parts by weight) A negative electrode was prepared in the same manner as in Sample 3, except for adding and mixing. That is, here, the amount of perhydropolysilazane added to 100 parts by weight of vinylidene fluoride resin as a binder is 2 (parts by weight).

<Preparation of Positive Electrode and Electrolyte> A positive electrode and an electrolyte were prepared in the same manner as in Sample 3.

<Assembly of Battery> A battery was assembled in the same manner as in Sample 1 to obtain a cylindrical nonaqueous electrolyte secondary battery. Note that this battery is referred to as Sample 4.

(Sample 5) <Preparation of Negative Electrode> In this example, vinylidene fluoride resin 100 (parts by weight) as a binder was mixed with toluene 10 as a solvent.
(Percent by weight) of a perhydropolysilazane solution of 50% by weight.
(Parts by weight) A negative electrode was prepared in the same manner as in Sample 3, except for adding and mixing. That is, in this case, the amount of perhydropolysilazane added to vinylidene fluoride resin 100 (parts by weight) as a binder is 5 (parts by weight).

<Preparation of Positive Electrode and Electrolyte> A positive electrode and an electrolyte were prepared in the same manner as in Sample 3.

<Assembly of Battery> A battery was assembled in the same manner as in Sample 1 to obtain a cylindrical nonaqueous electrolyte secondary battery. Note that this battery is referred to as Sample 5.

(Sample 6) <Preparation of Positive Electrode> Here, a vinylidene fluoride resin 100 (parts by weight) as a binder was mixed with toluene 10 as a solvent.
(% By weight) of the perhydropolysilazane solution
(Parts by weight) Except for addition and mixing, a positive electrode was prepared in the same manner as in Sample 1. That is, in this case, the amount of perhydropolysilazane added to vinylidene fluoride resin 100 (parts by weight) as a binder is 1.5 (parts by weight).

<Preparation of Negative Electrode> In this example, 15 (parts by weight) of a perhydropolysilazane solution having a concentration of 10 (% by weight) using toluene as a solvent was added to 100 parts by weight of vinylidene fluoride resin as a binder. A negative electrode was prepared in the same manner as in Sample 3, except for mixing. That is, here
The amount of perhydropolysilazane added to vinylidene fluoride resin 100 (parts by weight) as a binder is 1.5 (parts by weight).

<Preparation of Electrolyte and Assembly of Battery> An electrolyte was prepared in the same manner as in Sample 1, and a battery was assembled.
A cylindrical non-aqueous electrolyte secondary battery was obtained. Note that this battery is referred to as Sample 6.

(Sample 7) <Preparation of Positive Electrode> Here, vinylidene fluoride resin 100 (parts by weight) as a binder was mixed with toluene 10 as a solvent.
(Percent by weight) of a solution of perhydropolysilazane in 25
(Parts by weight) Except for addition and mixing, a positive electrode was prepared in the same manner as in Sample 1. That is, here, the amount of perhydropolysilazane added to vinylidene fluoride resin 100 (parts by weight) as a binder is 2.5 (parts by weight).

<Preparation of Negative Electrode> Here, 25 (parts by weight) of a 10% (by weight) perhydropolysilazane solution using toluene as a solvent was added to 100 parts by weight of vinylidene fluoride resin as a binder. A negative electrode was prepared in the same manner as in Sample 3, except for mixing. That is, here
The amount of perhydropolysilazane added to vinylidene fluoride resin 100 (parts by weight) as a binder is 2.5 (parts by weight).

<Preparation of Electrolyte and Assembly of Battery> An electrolyte was prepared in the same manner as in Sample 1, and a battery was assembled.
A cylindrical non-aqueous electrolyte secondary battery was obtained. Note that this battery is referred to as Sample 7.

(Sample 8) <Preparation of Positive Electrode> Here, vinylidene fluoride resin 100 (parts by weight) as a binder was mixed with toluene 10 as a solvent.
(Percent by weight) of a solution of perhydropolysilazane in 25
(Parts by weight) Except for addition and mixing, a positive electrode was prepared in the same manner as in Sample 1. That is, here, the amount of perhydropolysilazane added to vinylidene fluoride resin 100 (parts by weight) as a binder is 2.5 (parts by weight).

<Preparation of Negative Electrode> In this example, 50 (parts by weight) of a perhydropolysilazane solution having a concentration of 10 (% by weight) using toluene as a solvent was added to 100 parts by weight of vinylidene fluoride resin as a binder. A negative electrode was prepared in the same manner as in Sample 3, except for mixing. That is, here
Perhydropolysilazane was added in an amount of 5 (parts by weight) based on 100 parts by weight of vinylidene fluoride resin as a binder.
Becomes

<Preparation of Electrolyte Solution and Assembly of Battery> An electrolyte solution was prepared in the same manner as in Sample 1, and a battery was assembled.
A cylindrical non-aqueous electrolyte secondary battery was obtained. Note that this battery is referred to as Sample 8.

(Sample 9) A positive electrode was formed in the same manner as in Sample 3, a negative electrode was formed in the same manner as in Sample 1, an electrolyte was formed in the same manner as in Sample 1, and a battery was assembled in the same manner as in Sample 1. A non-aqueous electrolyte secondary battery was obtained. That is, in this battery, neither the positive electrode mixture nor the negative electrode mixture contains perhydropolysilazane. Note that this battery is referred to as Sample 9.

Evaluation of Characteristics The cycle characteristics of the nine battery samples prepared as described above were evaluated as follows. That is, first, at a maximum charging voltage of 4.2 (V) and a charging current of 1 (A),
A constant current constant voltage charge of 3 (hr) was performed under the condition of a temperature of 23 (° C.), and then a constant current discharge was performed so that the current became 1000 (mA) and the final voltage became 2.5 (V). The initial discharge capacity was determined. Thereafter, charge and discharge are performed for 100 times under the above conditions.
Cycle and 10 when the initial discharge capacity is 100
The discharge capacity maintenance ratio (%) at the 0th cycle was determined.

The batteries were disassembled after 100 cycles of charging and discharging, and the states of the positive electrode and the negative electrode were observed. Then, a case where no noticeable change such as swelling or falling off of the electrode mixture layer was observed was evaluated as ○, and a case where swelling or falling off of the electrode mixture layer partially occurred was evaluated as Δ.

The content of the above perhydropolysilazane to 100 parts by weight of the binder in the positive electrode mixture layer and / or the negative electrode mixture layer of each battery sample, the initial discharge capacity and 1%
Table 1 also shows the discharge capacity maintenance ratio (%) at the 00th cycle and the state of the electrodes at the 100th cycle.

[0080]

[Table 1]

As can be seen from Table 1, in the batteries 1 to 8 having the positive electrode mixture layer and / or the negative electrode mixture layer containing perhydropolysilazane, the positive electrode mixture layer and the negative electrode mixture It can be seen that the discharge capacity retention rate (%) after 100 cycles is significantly improved as compared with Sample 9, which is a battery containing no perhydropolysilazane in any of the layers. Also, looking at the state of the electrode at the 100th cycle, in sample 9, swelling and falling off of the electrode mixture layer partially occurred in both the positive electrode and the negative electrode. In a positive electrode and / or a negative electrode having a positive electrode mixture layer and / or a negative electrode mixture layer containing polysilazane, no noticeable change such as swelling or falling off of the electrode mixture layer was observed, and a positive electrode mixture containing no perhydropolysilazane was observed. In the positive electrode and / or the negative electrode having the mixture layer and / or the negative electrode mixture layer, the electrode mixture layer partially swells and falls off.

That is, according to the present invention, since a composite coating film of perhydropolysilazane and a binder is formed, the electrode material containing perhydropolysilazane is prevented from dropping from the electrode current collector. It has been confirmed that a secondary battery having improved charge / discharge cycle characteristics and life characteristics can be manufactured.

It was also confirmed that the effect of the present invention was further enhanced when perhydropolysilazane was added to both the positive electrode mixture layer and the negative electrode mixture layer.

[0084]

As described above, in the method for manufacturing a secondary battery according to the present invention, perhydropolysilazane is contained in the positive electrode mixture and / or the negative electrode mixture, and the positive electrode mixture containing this perhydropolysilazane is contained. After applying the agent and / or the negative electrode mixture on the positive electrode current collector and / or the negative electrode current collector, a heat treatment is performed to form a composite coating film of the perhydropolysilazane and the binder. Accordingly, it is possible to prevent the electrode material in the electrode mixture containing the perhydropolysilazane from falling off from the electrode current collector, and to manufacture a secondary battery with improved charge / discharge cycle characteristics and life characteristics.

Further, silica is formed by heat-treating perhydropolysilazane in this way, whereby the compatibility with general fluorine-based polymers such as vinyl fluoride resin and vinylidene fluoride resin as a binder is further improved. Improved, and also electrochemically stable, which also prevents the electrode material in the electrode mixture from falling off the electrode current collector,
It is possible to manufacture a secondary battery having improved charge / discharge cycle characteristics and life characteristics.

Claims (3)

[Claims] An anode current collector is formed by applying a cathode mixture comprising at least a cathode material and a binder on at least one main surface of a cathode current collector to form a cathode mixture layer. On at least one main surface, a negative electrode mixture composed of at least a negative electrode material and a binder is applied to form a negative electrode mixture layer, and a negative electrode is formed. The positive electrode and the negative electrode are opposed to each other via an electrolyte phase. A method for producing a secondary battery, wherein the positive electrode mixture and / or the negative electrode mixture contains perhydropolysilazane, and the positive electrode mixture and / or the negative electrode mixture containing the perhydropolysilazane are provided. A method for producing a secondary battery, comprising forming a composite coating film of the above-mentioned perhydropolysilazane and a binder by performing a heat treatment after applying the agent. 2. In the positive electrode mixture and / or the negative electrode mixture containing perhydropolysilazane, the content of the perhydropolysilazane is 0.5 to 30 parts by weight based on 100 parts by weight of the binder. The method for manufacturing a secondary battery according to claim 1. 3. The method according to claim 1, wherein the negative electrode material is a material containing a carbon material capable of being doped and dedoped with lithium, and the positive electrode material is a material containing a transition metal composite oxide containing lithium. Of manufacturing a secondary battery.