JP2002134173A - Method for manufacturing nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a nonaqueous secondary battery. SOLUTION: This method comprises the steps of interposing a separator 3 between a positive electrode 1 and a negative electrode 2, to form an electrode group 4 with a laminated structure in which the area ratio of exposed surface thereof to non-exposed surface is <=0.075, and impregnating the electrode group 4 with a nonaqueous electrolyte. At least one of the positive electrode 1 and the negative electrode 2 contains either surfactants of anionic surfactant or nonionic surfactant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a non-aqueous secondary battery.

[0002]

2. Description of the Related Art In recent years, with the development of electronic equipment, there has been a demand for the development of a secondary battery that is small, lightweight, has a high energy density, and can be repeatedly charged and discharged. Such a secondary battery includes a negative electrode using lithium or a lithium alloy as an active material, a positive electrode containing an oxide, sulfide, or selenide such as molybdenum, vanadium, titanium, or niobium as an active material, and a nonaqueous electrolyte. Non-aqueous electrolyte secondary batteries having the following are known.

Recently, for example, coke, graphite,
An electrode in which a separator is interposed between a negative electrode containing a carbonaceous material such as carbon fiber, resin fired body, and pyrolytic gas phase carbon that absorbs and releases lithium ions and a positive electrode containing an active material (eg, lithium composite oxide). A non-aqueous electrolyte secondary battery including a group and a non-aqueous electrolyte held by the electrode group has been proposed.

Japanese Unexamined Patent Publication No. 10-12273 discloses a non-aqueous electrolyte secondary battery using a carbonaceous material as a negative electrode active material, among nonionic fluorine-based surfactants having a perfluoroalkyl group. A non-aqueous electrolyte secondary battery using an electrolyte to which one or more activators are added is disclosed.

On the other hand, Japanese Patent Publication No. 2974739 discloses that
In an organic electrolyte battery including a positive electrode containing a metal element, a negative electrode made of an alkali metal or a compound containing an alkali metal, and an organic electrolyte as a power generating element, the organic electrolyte is CnF2n + 1SO3M (n is 2 or more) as an electrolyte. And M is an alkali metal) and has a water content of 50 to 100.
An organic electrolyte battery containing 0 ppm is disclosed.

[0006]

However, when the shape of the electrode group is made flat to reduce the thickness of the secondary battery, as disclosed in Japanese Patent Application Laid-Open Nos. 10-12273 and 2974739. When a surfactant is added to the non-aqueous electrolyte and the non-aqueous electrolyte is injected into the flat electrode group described above, the non-aqueous electrolyte moves because the non-aqueous electrolyte moves long in the flat electrode group. Since the diffusion rate of the liquid is slowed and the distribution of the non-aqueous electrolyte in the electrode group is likely to be biased, the internal resistance of the secondary battery is increased, so that a sufficient utilization rate and a sufficient discharge capacity cannot be obtained.

According to the present invention, when the area ratio of the exposed surface of the laminated structure to the non-exposed surface of the laminated structure is 0.075 or less, the non-aqueous electrolyte can be uniformly held by the electrode group. Therefore, an object of the present invention is to provide a method for manufacturing a non-aqueous secondary battery in which the internal resistance is reduced and the discharge capacity is improved.

[0008]

According to a method of manufacturing a non-aqueous secondary battery according to the present invention, a separator is interposed between a positive electrode and a negative electrode, and the area of the exposed surface of the laminated structure relative to the unexposed surface of the laminated structure is determined. A step of producing an electrode group having a ratio of 0.075 or less, and a step of impregnating the electrode group with a non-aqueous electrolyte, and at least one of the positive electrode and the negative electrode has an anionic interface It is characterized by containing at least one of a surfactant and a nonionic surfactant.

The method for manufacturing a non-aqueous secondary battery according to the present invention comprises:
A method for manufacturing a non-aqueous secondary battery, comprising: a step of forming an electrode group with a separator interposed between a positive electrode and a negative electrode; and a step of impregnating the electrode group with a non-aqueous electrolyte. The area ratio of the exposed surface of the laminated structure to the non-exposed surface of the laminated structure is 0.075 or less, and at least one of the positive electrode and the negative electrode includes an anionic surfactant and a nonionic interface. It is characterized by being produced by a method including a step of preparing a slurry containing at least one of a surfactant and an active material among activators, and a step of applying the slurry to a current collector. is there.

In the method for manufacturing a non-aqueous secondary battery according to the present invention, the step of impregnating the non-aqueous electrolyte may be performed after the electrode group is housed in the outer package or before the electrode group is housed in the outer package. Done in

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a non-aqueous secondary battery according to the present invention will be described.

(First Step) A separator is interposed between a positive electrode and a negative electrode, and an electrode group is produced in which the area ratio of the exposed surface of the laminated structure to the unexposed surface of the laminated structure is 0.075 or less.

A specific method of manufacturing the electrode group will be described with reference to FIGS.

(1) The positive electrode 1 and the negative electrode 2 are laminated with the separator 3 interposed therebetween to obtain the electrode group 4 having the structure shown in FIG.

In this electrode group 4, when the length of the long side is defined as w, the length of the short side is defined as d, and the thickness is defined as t, the laminated structure is not exposed. Total area of surface S
0 is calculated by w × d × 2. Further, the total area S1 of the exposed surface of the laminated structure is calculated by (w × t + d × t) × 2. However, the thickness t of the electrode group is measured in a state where a pressure of 500 g / cm 2 is applied to the surface having the maximum area of the electrode group (the surface whose area is calculated by w × d).

Therefore, in the electrode group 4, the area ratio of the exposed surface of the laminated structure to the unexposed surface of the laminated structure is calculated by the following equation (1).

Area ratio = S 1 / S 0 = {(w × t + d × t) × 2} / (w × d × 2) (1) (2) A separator is interposed between the positive electrode and the negative electrode to form a spiral. After turning, the electrode group 5 having the structure shown in FIGS.

In this electrode group 5, when the length of the long side is defined as w, the length of the short side is defined as d, and the thickness is defined as t, the laminated structure is not exposed. Total area of surface S
0 is calculated by (w × d + w × t) × 2. The total area S1 of the exposed surface of the laminated structure is calculated by t × d × 2. However, the thickness t of the electrode group 5 is measured in a state where a pressure of 500 g / cm 2 is applied to the surface having the maximum area of the electrode group (the surface whose area is calculated by w × d).

Accordingly, in the electrode group 5, the area ratio of the exposed surface of the laminated structure to the unexposed surface of the laminated structure is calculated by the following equation (2).

Area ratio = S 1 / S 0 = (t × d × 2) / {(w × d + w × t) × 2} (2) (3) A separator is interposed between the positive electrode and the negative electrode to form a spiral. The electrode group 6 having the structure shown in FIG.
Get.

In this electrode group 6, when the height of the cylinder is w and the length of the diameter is 2r, the total area S0 of the unexposed surface of the laminated structure is calculated as 2πr × w. The total area S1 of the exposed surface of the laminated structure is calculated by πr2 × 2.

Therefore, in the electrode group 6, the area ratio of the exposed surface of the laminated structure to the unexposed surface of the laminated structure is calculated by the following equation (3).

Area ratio = S 1 / S 0 = (πr 2 × 2) / (2πr × w) (3) In the surface of the electrode group, the area ratio of the exposed surface of the laminated structure to the non-exposed surface of the laminated structure is set to 0.1. The reason why the ratio is set to 075 or less is that if the area ratio exceeds 0.075, it is impossible to sufficiently reduce the thickness and size of the nonaqueous secondary battery.
The smaller the area ratio, the more advantageous the thinning and miniaturization of the nonaqueous secondary battery. It is difficult to be. Therefore, the area ratio is
It is preferable to set it in the range of 0.03 to 0.075.
A more preferred range is from 0.04 to 0.06.

The positive electrode is manufactured, for example, by the method described below.

First, a slurry is prepared by kneading an active material, a conductive material, a binder and, if necessary, a surfactant together with a solvent. The obtained slurry is applied to a current collector, dried, and subjected to pressure molding to produce the positive electrode.

Examples of the active material include various oxides (eg, lithium manganese composite oxide such as LiMn 2 O 4, manganese dioxide, lithium-containing nickel oxide such as LiNiO 2, lithium-containing cobalt oxide such as LiCoO 2, lithium Containing cobalt nickel oxide, lithium-containing amorphous vanadium pentoxide, etc.), and chalcogen compounds (eg, titanium disulfide, molybdenum disulfide, etc.). Among them, it is preferable to use a lithium manganese composite oxide, a lithium-containing cobalt oxide, and a lithium-containing nickel oxide.

Examples of the conductive material include artificial graphite, carbon black such as acetylene black and Ketjen black, and nickel powder. One or two or more selected from the above-mentioned types can be used for such a conductive material.

Examples of the binder include polyvinylidene fluoride (PVdF) and copolymers containing vinylidene fluoride (VdF) as a monomer component. Examples of the copolymer include a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), a copolymer of three kinds of VdF, HFP and tetrafluoroethylene (TFE), and (meth) Acrylic acid and its esters, alkylene oxide adducts and the like can be mentioned. Such binders include one or two selected from the types described above.
More than one polymer can be used.

As the current collector of the positive electrode, for example, aluminum foil, aluminum mesh, aluminum expanded metal, aluminum punched metal and the like can be used.

The negative electrode is manufactured, for example, by the method described below.

First, a slurry is prepared by kneading a carbonaceous material that absorbs and releases lithium ions, a binder and, if necessary, a surfactant together with a solvent. The obtained slurry is applied to a current collector, dried, and subjected to pressure molding to produce the negative electrode.

Examples of the carbonaceous material include those obtained by firing organic polymer compounds such as phenolic resin, polyacrylonitrile, and cellulose, those obtained by firing coke and pitch, artificial graphite, and natural graphite. And the like. Above all, in an atmosphere of an inert gas such as an argon gas or a nitrogen gas, 500 ° C. to 30 ° C.
It is preferable to use a carbonaceous material obtained by firing the organic polymer compound at a temperature of 00 ° C. under normal pressure or reduced pressure.

Examples of the binder include those similar to those described above for the positive electrode.

From the viewpoint of improving conductivity, the negative electrode is
A conductive material may be included. Examples of the conductive material include artificial graphite, carbon black such as acetylene black and Ketjen black, and nickel powder.

As the current collector, for example, copper foil, copper mesh, copper expanded metal, copper punched metal, or the like can be used.

In the present invention, at least one of the positive electrode and the negative electrode contains at least one of an anionic surfactant and a nonionic surfactant. As the anionic surfactant and the nonionic surfactant, those having a perfluoroalkyl group are desirable.

The concentration of the surfactant is preferably in the range of 0.01 to 0.5 part based on 100 parts of the active material.

As the separator, for example, a porous sheet made of polyolefin (for example, polyethylene or polypropylene) or a polymer electrolyte layer can be used. The polymer electrolyte layer is formed by impregnating the non-aqueous electrolyte with a polymer electrolyte layer precursor containing a polymer having a function of holding the non-aqueous electrolyte, and then performing a gelling treatment such as a heat treatment as necessary. can get. It is desirable that the polymer having the function of holding the non-aqueous electrolyte has a binding function. Examples of the polymer having the function of retaining the nonaqueous electrolyte and the binding function include, for example, a polyethylene oxide derivative, a polypropylene oxide derivative, a polymer containing the derivative, polytetrafluoropropylene, vinylidene fluoride (VdF), and hexafluoropropylene ( HFP), polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polymers having an acrylic structure, and the like.

(Second Step) After the electrode group is housed in a package, a non-aqueous electrolyte is injected.

The shape of the exterior material can be, for example, a bag shape, a bottomed cylindrical shape, a bottomed square cylindrical shape, or the like.

The exterior material can be formed, for example, from a metal plate, a sheet in which a metal layer is interposed between a thermoplastic resin layer and a resin layer, or the like.

The thermoplastic resin layer serves as a heat sealing surface of the exterior material. Examples of the heat-fusible resin include modified polyethylene phthalate, acid-modified polyethylene, acid-modified polypropylene, ionomer, ethylene vinyl acetate (EVA) and the like. The thermoplastic resin layer may have a single layer or a multilayer structure composed of a plurality of thermoplastic resins.

The metal layer has a role of preventing intrusion of moisture. The metal layer can be formed from, for example, aluminum, nickel, and stainless steel.

The resin layer has a role of protecting the metal layer. The resin layer can be formed from, for example, polyolefin such as polyethylene terephthalate (PET) and polypropylene. The resin layer,
It can be a single layer or a multilayer structure composed of a plurality of resins.

The metal plate can be formed of, for example, aluminum, nickel, and stainless steel.

The non-aqueous electrolyte is prepared by dissolving an electrolyte such as a lithium salt in a non-aqueous solvent.

Examples of the non-aqueous solvent include ethylene carbonate (EC) and propylene carbonate (P
C), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC),
Ethyl methyl carbonate (EMC), γ-butyrolactone (γ-BL), sulfolane, acetonitrile, 1,
2-dimethoxyethane, 1,3-dimethoxypropane,
Dimethyl ether, tetrahydrofuran (THF), 2
-Methyltetrahydrofuran and the like.
The non-aqueous solvents may be used alone or as a mixture of two or more.

Examples of the electrolyte include lithium perchlorate (LiClO 4) and lithium hexafluorophosphate (L
lithium salts such as iPF6), lithium borofluoride (LiBF4), lithium arsenic hexafluoride (LiAsF6), and lithium trifluoromethanesulfonate (LiCF3 SO3).

After the second step, the exterior material is sealed, and the like, to obtain a non-aqueous secondary battery. In the present invention,
After the electrode group produced in the first step is impregnated with a non-aqueous electrolyte, the electrode group may be housed in an exterior material and subjected to sealing treatment to obtain a non-aqueous secondary battery.

In the method of manufacturing a non-aqueous secondary battery according to the present invention described above, a separator is interposed between a positive electrode and a negative electrode,
A step of producing an electrode group in which the area ratio of the surface where the laminated structure is exposed to the non-exposed surface of the laminated structure is 0.075 or less; and a step of impregnating the electrode group with a non-aqueous electrolyte, and At least one of the positive electrode and the negative electrode contains at least one of an anionic surfactant and a nonionic surfactant.

An electrode group in which the area ratio of the surface where the laminated structure is exposed to the surface where the laminated structure is not exposed is 0.075 or less can reduce the thickness and slimness of the secondary battery. The diffusion distance of the non-aqueous electrolyte is slow because the movement distance of the aqueous electrolyte is long and the exposed surface of the laminated structure that the non-aqueous electrolyte easily penetrates is small. As in the present invention, at least one of the positive electrode and the negative electrode
By including at least one of an anionic surfactant and a nonionic surfactant, the diffusion rate of the non-aqueous electrolyte can be increased. The electrolyte can be permeated. As a result, the internal resistance of the non-aqueous secondary battery can be reduced, so that the utilization factor, the discharge capacity, and the like can be improved.

In the method for manufacturing a non-aqueous secondary battery according to the present invention, at least one of the positive electrode and the negative electrode may be provided with at least one of an anionic surfactant and a nonionic surfactant. By preparing a method including a step of preparing a slurry containing an agent and an active material, and a step of applying the slurry to a current collector, the wettability of the active material is improved by a surfactant attached to the surface. Therefore, it is possible to prepare a slurry having a viscosity that is optimal for application within a short time, and it is possible to reduce a variation in the viscosity of the slurry. As a result, it is possible to produce a positive electrode and a negative electrode having excellent performance and small variations in a short time.

[0053]

Embodiments of the present invention will be described below in detail.

Examples 1 to 6 (1) Preparation of positive electrode Lithium cobaltate (LiCoO) having an average particle size of 5 μm
Lithium perfluorooctanesulfonate (C8F17SO3Li) was added to a mixed powder consisting of 90% of the active material composed of 2) and 6% of graphite at a ratio shown in Table 1 below based on 100 parts of the active material, and mixed. The resulting mixed powder is put into a solution in which 4% of polyvinylidene fluoride (PVdF) is dissolved in N-methyl-2-pyrrolidone (NMP) and kneaded at a peripheral speed of 90 m / min for 1 hour to form a slurry. Prepared. The obtained slurry was applied on an aluminum foil so that the applied weight after drying was 200 g / m2, and dried to obtain a positive electrode.

During the production of the positive electrode, the viscosity of the slurry was measured with a B8M viscometer for 60 minutes from the start of slurry preparation (start of kneading).

(2) Preparation of Negative Electrode Polyvinylidene fluoride (PVdF) 10%
A slurry was prepared by adding 90% of graphite having an average particle size of 10 μm to a solution dissolved in methyl-2-pyrrolidone (NMP) and kneading the mixture at a peripheral speed of 90 m / min for 1 hour. The obtained slurry was applied on a copper foil so that the applied weight after drying was 100 g / m2, and dried to obtain a negative electrode.

(3) Polymer Electrolyte First, PVdF was dissolved in NMP, and polyacrylonitrile (PAN) particles were dispersed in the obtained solution. After applying the obtained solution on a glass plate, it was immersed in pure water and dried to prepare a polymer electrolyte precursor sheet.

(4) Preparation of Non-Aqueous Electrolyte LiPF 6 as an electrolyte was mixed with ethylene carbonate (EC) and ethyl methyl carbonate (MEC) at a concentration of 1 mol in a non-aqueous solvent mixed at a volume ratio of 1: 2.
1 / L to prepare a non-aqueous electrolytic solution.

(5) Preparation of Electrode Group The positive electrode was cut into a size of 50 mm × 50 mm, and the negative electrode was cut into 55 mm.
The sheet was cut into a size of mm × 55 mm, and the polymer electrolyte precursor sheet was cut into a size of 60 mm × 60 mm.
The positive electrode and the negative electrode are laminated with a polymer electrolyte precursor sheet interposed therebetween, and have the structure shown in FIG. 1 described above,
A flat electrode group having an area ratio of the surface where the laminated structure was exposed to the surface where the laminated structure was not exposed was 0.033 was obtained.
An aluminum lead was welded to the positive electrode and a copper lead was welded to the negative electrode. Next, the electrode group was accommodated in a bag made of an aluminum laminate film including a thermoplastic resin layer, an aluminum layer, and a resin layer such that the positive electrode lead and the negative electrode lead extended outside the bag.

0.3 g of the non-aqueous electrolyte was injected into the bag of the aluminum laminated film, and the opening of the bag was sealed to obtain a thin non-aqueous electrolyte secondary battery having the structure shown in FIG.

That is, the thin nonaqueous electrolyte secondary battery includes a stacked electrode group 4 in which a positive electrode 1 and a negative electrode 2 are stacked with a separator 3 interposed therebetween, and the electrode group 4 is housed therein.
And an exterior material 7 made of a film bag. An aluminum positive electrode lead 8 connected to the positive electrode 1 extends outside the exterior material 7. On the other hand, a copper negative electrode lead 9 connected to the negative electrode 2 extends outside the exterior material 7.

(Examples 7 to 12) Thin non-aqueous electrolyte secondary batteries were manufactured in the same manner as in Examples 1 to 6 except that a perfluoroalkylethylene oxide adduct was used as a nonionic surfactant. .

Comparative Example 1 A thin non-aqueous electrolyte secondary battery was manufactured in the same manner as in Examples 1 to 6 except that no surfactant was added.

Comparative Example 2 A thin non-aqueous electrolyte secondary battery was manufactured in the same manner as in Examples 1 to 6 except that a perfluoroalkyltrimethylammonium salt was used as the cationic surfactant.

Comparative Example 3 A thin non-aqueous electrolyte secondary battery was manufactured in the same manner as in Examples 1 to 6 except that a perfluoroalkylaminosulfonic acid salt was used as an amphoteric surfactant.

FIG. 6 shows the time-dependent changes in the slurry viscosity during the preparation of the positive electrode slurry for Examples 1 to 12 and Comparative Examples 1 to 3. In FIG. 6, a range surrounded by two curves indicated by two leader lines is a measured viscosity distribution. In this example, the optimum range of the optimum viscosity for the coating was determined from the viscosity when the slurry containing no surfactant was kneaded for 2 hours. In this case, 7000 to 8000 mPa · s
ec.

As is clear from FIG. 6, in Examples 1 to 12 using the positive electrode slurry containing an anionic surfactant or a nonionic surfactant, the dispersion of the slurry viscosity was small and within one hour from the start of stirring. It can be seen that the slurry viscosity reached an appropriate value.

On the other hand, in Comparative Example 1 in which the positive electrode slurry to which no surfactant was added was used, the dispersion of the viscosity was large, and it was found that the proper viscosity was not reached within 1 hour from the start of stirring.

Examples 13 to 18 (1) Preparation of Positive Electrode Lithium cobaltate (LiCoO) having an average particle size of 5 μm
A mixed powder composed of 90% of the active material composed of 2) and 6% of graphite was prepared. 4% of polyvinylidene fluoride (PVdF) is added to N-methyl-2-pyrrolidone (NM
The resulting mixed powder was charged into the solution dissolved in P) and kneaded at a peripheral speed of 90 m / min for 1 hour to prepare a slurry. The obtained slurry was applied on an aluminum foil so that the applied weight after drying was 200 g / m2, and dried to obtain a positive electrode.

(2) Preparation of Negative Electrode Lithium perfluorooctanesulfonate (C8F17SO3Li) was added to 90% of graphite having an average particle size of 10 μm to 100 parts of the active material in a ratio shown in Table 1 below and mixed. Polyvinylidene fluoride (PVd
F) The mixed powder was charged into a solution in which 10% was dissolved in N-methyl-2-pyrrolidone (NMP), and the peripheral speed was 90 m / m.
A slurry was prepared by kneading for 1 hour in.
The obtained slurry is dried on a copper foil to a coating weight of 100
g / m2 and dried to obtain a negative electrode.

The preparation of the negative electrode slurry was started (the kneading was started).
After 60 minutes, the viscosity of the slurry was measured with a B8M viscometer.

A thin non-aqueous electrolyte secondary battery was manufactured in the same manner as in Examples 1 to 6 except that the obtained positive electrode and negative electrode were used.

Examples 19 to 24 Thin non-aqueous electrolyte secondary batteries were produced in the same manner as in Examples 13 to 18 except that a perfluoroalkylethylene oxide adduct was used as the nonionic surfactant. .

Comparative Example 4 A thin non-aqueous electrolyte secondary battery was manufactured in the same manner as in Examples 13 to 18 except that a perfluoroalkyltrimethylammonium salt was used as the cationic surfactant.

Comparative Example 5 A thin non-aqueous electrolyte secondary battery was manufactured in the same manner as in Examples 13 to 18 except that a perfluoroalkylaminosulfonic acid salt was used as the amphoteric surfactant.

Table 2 below shows the slurry viscosities 60 minutes after the start of kneading for Examples 13 to 24 and Comparative Examples 1 and 4 to 5. The suitable range of the slurry viscosity in this example is 4000 to 5000 mPa · sec.

[0077]

[Table 1]

[0078]

[Table 2]

As is clear from Table 2, in Examples 13 to 24 in which the negative electrode slurry containing an anionic surfactant or a nonionic surfactant was used, the dispersion of slurry viscosity was small and one hour after the start of stirring. It can be seen that the slurry viscosity reaches an appropriate value.

On the other hand, in Comparative Example 1 in which the negative electrode slurry containing no surfactant was used, the viscosity was large, and the viscosity for one hour from the start of stirring was higher than the proper viscosity, and the proper viscosity was not obtained for one hour of stirring. It can be seen that the viscosity does not reach.

(Example 25) The average particle diameter of the positive electrode active material was 3
Except for changing to μm, a positive electrode slurry was prepared in the same manner as in Example 3 described above, and the viscosity one hour after the start of kneading was measured with a B8M viscometer. The results are shown in Table 3 below.

Comparative Example 6 The average particle size of the positive electrode active material was 3 μm.
Except for changing to m, a positive electrode slurry was prepared in the same manner as in Comparative Example 1 described above, and the viscosity one hour after the start of kneading was measured with a B8M viscometer. The results are shown in Table 3 below. The suitable viscosity of the slurries of Example 25 and Comparative Example 6 is 8000 to 10000 mPa · sec.

[0083]

[Table 3]

As is clear from Table 3, in Example 25 using the positive electrode slurry containing an anionic surfactant, the dispersion of the slurry viscosity was small, and the slurry viscosity reached an appropriate value within one hour from the start of stirring. Understand.

On the other hand, in Comparative Example 6 in which the positive electrode slurry containing no surfactant was used, the viscosity varied greatly, and the viscosity for one hour from the start of stirring was higher than the appropriate viscosity, and the viscosity was not adequate for one hour of stirring. It can be seen that the viscosity does not reach.

Example 26 The average particle size of the negative electrode active material was 2
Except for changing to 0 μm, a negative electrode slurry was prepared in the same manner as in Example 15 described above, and the viscosity one hour after the start of kneading was measured with a B8M viscometer.
Shown in

Comparative Example 7 The average particle size of the negative electrode active material was 20
Except for changing to μm, a negative electrode slurry was prepared in the same manner as in Comparative Example 1 described above, and the viscosity one hour after the start of kneading was measured with a B8M viscometer. The results are shown in Table 4 below. The appropriate viscosity of the slurries of Example 26 and Comparative Example 7 is 3000 to 4000 mPa · sec.

[0088]

[Table 4]

As is clear from Table 4, in Example 26 using the negative electrode slurry containing the anionic surfactant, the dispersion of the slurry viscosity was small, and the slurry viscosity reached an appropriate value within one hour from the start of stirring. Understand.

On the other hand, in Comparative Example 7 in which the negative electrode slurry containing no surfactant was used, the viscosity was large, and the viscosity for one hour from the start of stirring was higher than the appropriate viscosity. It can be seen that the viscosity does not reach.

The obtained Examples 1 to 24 and Comparative Examples 1 to 5
About 24 hours after the injection of the non-aqueous electrolyte, heating at 100 ° C. for 1 minute, and then cooling to room temperature.
A constant current / constant voltage charging with a final voltage of 4.2 V was performed at 2 C equivalent, the discharge capacity at the time of discharging at 1 C was measured, and the utilization at 1 C was calculated from the obtained discharge capacity. It is shown in Table 5 below. Next, the resistance value after discharge was measured by an AC method, and the results are shown in Table 5 below. Continued,
The secondary battery was disassembled, and the surface state of the negative electrode was visually observed. Uncharged portions have the black color of graphite, and charged portions have a gold color. Based on these findings, uneven charging on the negative electrode surface was examined. The results are shown in Table 5 below.

[0092]

[Table 5]

As is clear from Table 5, the area ratio of the exposed surface of the laminated structure to the non-exposed surface of the laminated structure was 0.075 or less using a positive electrode or a negative electrode containing an anionic or nonionic surfactant. It can be seen that the secondary batteries of Examples 1 to 24 in which the electrode group is manufactured have a high utilization rate at 1 C, a low internal resistance, and a uniform charge / discharge reaction in the negative electrode.

On the other hand, the secondary battery of Comparative Example 1, in which no surfactant was added, had a lower utilization factor at 1 C and a higher internal resistance than those of Examples 1 to 24, and furthermore, had a negative electrode charged and discharged. It can be seen that the reaction occurs unevenly. on the other hand,
Comparative Examples 2 to 2 in which the surfactant is cationic or amphoteric
In the secondary battery of No. 5, although the charge / discharge reaction occurs uniformly in the negative electrode, the utilization rate at 1C is lower than that of Examples 1 to 24.

[0095]

As described above in detail, according to the present invention, the electrode group is uniformly impregnated with the non-aqueous electrolyte, and the internal resistance is low.
A method for manufacturing a non-aqueous secondary battery with improved utilization and discharge capacity can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an electrode group included in a non-aqueous secondary battery manufactured by a method according to the present invention.

FIG. 2 is a perspective view showing another example of the electrode group included in the non-aqueous secondary battery manufactured by the method according to the present invention.

FIG. 3 is a front view showing the electrode group of FIG. 2;

FIG. 4 is a perspective view showing still another example of the electrode group included in the non-aqueous secondary battery manufactured by the method according to the present invention.

FIG. 5 is a plan view showing a thin non-aqueous electrolyte secondary battery of Example 1.

FIG. 6 is a characteristic diagram showing the relationship between slurry preparation time and slurry viscosity in the thin nonaqueous electrolyte secondary batteries of Examples 1 to 12 and Comparative Examples 1 to 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... positive electrode, 2 ... negative electrode, 3 ... separator, 4 ... electrode group, 5 ... electrode group, 6 ... electrode group, 7 ... exterior material, 8 ... positive electrode lead, 9 ... negative electrode lead.

Continuation of front page (72) Inventor Masahiro Iwaku 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Corporation F-term (reference) 5H029 AJ03 AJ06 AK03 AL07 AM03 AM04 AM07 BJ04 CJ22 CJ23 DJ04 HJ00

Claims (2)

[Claims] 1. A step of forming an electrode group in which a separator is interposed between a positive electrode and a negative electrode, and an area ratio of an exposed surface of the laminated structure to an unexposed surface of the laminated structure is 0.075 or less; Impregnating the group with a non-aqueous electrolyte,
And manufacturing at least one of the positive electrode and the negative electrode, wherein the non-aqueous secondary battery includes at least one of an anionic surfactant and a nonionic surfactant. Method. 2. A method for producing a non-aqueous secondary battery, comprising: a step of forming an electrode group with a separator interposed between a positive electrode and a negative electrode; and a step of impregnating the electrode group with a non-aqueous electrolyte. The area ratio of the exposed surface of the laminated structure to the unexposed surface of the laminated structure on the surface of the electrode group is 0.075 or less, and at least one of the positive electrode and the negative electrode has an anionic surfactant. Preparing a slurry containing at least one of a surfactant and a nonionic surfactant and an active material, and applying the slurry to a current collector. A method for producing a non-aqueous secondary battery.