JP2002042888A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery having excellent adhesion of a conductive material layer to a metallic current collector, excellent current collecting performance of a positive electrode mix layer and excellent high-rate discharge performance. SOLUTION: In this nonaqueous electrolyte secondary battery, a conductive material layer including conductive material and a binder is provided between a positive electrode mix and a metallic current collector, and the binder contains carboxymethyl cellulose.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art In recent years, electronic devices such as a portable radio telephone, a portable personal computer, and a portable video camera have been developed, and various electronic devices have been reduced in size to be portable. Along with this, a battery having a high energy density and a light weight is also adopted as a built-in battery.

A typical battery that meets such requirements is:
Particularly, an active material such as lithium metal or lithium alloy, or a lithium intercalation compound in which lithium ions are occluded in carbon as a host material is used as a negative electrode material, and LiC
This is a non-aqueous electrolyte secondary battery using an aprotic organic solvent in which a lithium salt such as 10 ₄ or LiPF ₆ is dissolved as an electrolyte. Note that a host substance here refers to a substance that can occlude and release lithium ions.

In this nonaqueous electrolyte secondary battery, a positive electrode active material that reversibly electrochemically reacts with lithium ions, such as a lithium-cobalt composite oxide, is coated on both sides or one side of a positive electrode current collector as a support. The positive electrode plate that holds the negative electrode material, the negative electrode plate that holds the negative electrode material on both or one side of the negative electrode current collector that is the support, and the electrolytic solution that is held between the positive electrode plate and the negative electrode plate. And a separator for preventing a short circuit between the two electrode plates.

[0005] The current collector of the positive electrode plate is used to improve the adhesion between the current collector and the positive electrode mixture layer and the current collecting property.
A conductive material, a binder made of polyvinylidene fluoride, etc., N-
A conductive material paste obtained by mixing an organic solvent such as methyl-2-pyrrolidone is applied to the surface of a metal current collector and dried to form a conductive material layer. From above, a positive electrode active material, a binder made of polyvinylidene fluoride or the like, N-methyl-2-
A positive electrode mixture paste obtained by mixing an organic solvent such as pyrrolidone or the like is applied and dried to form a positive electrode plate having a conductive material layer between the metal current collector and the positive electrode mixture.

[0006]

However, the above-mentioned binder composed of polyvinylidene fluoride or the like of the conductive material paste is prepared from N-methyl-2-pyrrolidone contained in the positive electrode mixture paste applied from above the conductive material layer. Since it is soluble in an organic solvent such as, when the positive electrode mixture paste is applied, the binder composed of polyvinylidene fluoride and the like contained in the conductive material layer is dissolved again in the positive electrode mixture paste, so that the conductive material layer Due to insufficient adhesion and current collection with the metal current collector,
There has been a problem that the current collection performance of the positive electrode mixture layer becomes insufficient, and the high-rate discharge performance of the battery decreases.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In a non-aqueous electrolyte secondary battery, a conductive material is provided between a positive electrode mixture and a metal current collector. A conductive material layer containing a binder is provided, and the binder contains carboxymethyl cellulose.

Further, the present invention is characterized in that in the above nonaqueous electrolyte secondary battery, the amount of carboxymethylcellulose added is 0.5 to 5% by weight based on the total weight of the conductive material layer.

Further, the present invention is characterized in that, in the above nonaqueous electrolyte secondary battery, the conductive material is a carbon material, and in particular, the carbon material is graphite.

Further, the present invention is characterized in that in the above nonaqueous electrolyte secondary battery, the thickness of the conductive material layer is 1 μm to 5 μm.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail.

The non-aqueous electrolyte secondary battery of the present invention (hereinafter referred to as
It is referred to as "battery of the present invention". ) Comprises at least a positive electrode plate, a negative electrode plate, a non-aqueous electrolyte, etc., and comprises a conductive material layer containing a conductive material and a binder between the positive electrode mixture and the metal current collector, wherein the binder is It is characterized by containing carboxymethylcellulose.

The conductive material layer is obtained by applying a conductive material paste made of a conductive material, carboxymethylcellulose (CMC), and water in which carboxymethylcellulose (CMC) is dissolved, onto a metal current collector, and drying the paste.

As the metal current collector, a metal foil, an expanded metal, a punching metal, a composite thereof, or the like can be used, but the present invention is not particularly limited to these current collectors.

Note that carboxymethylcellulose (CM
C) is usually a sodium salt, but there are also ammonium salts and lithium salts. In the present invention, all of these salts can be used alone or in combination.

Generally, an organic solvent such as N-methyl-2-pyrrolidone is used as a solvent for the positive electrode mixture paste. Therefore, as a binder for the conductive material layer,
By using carboxymethyl cellulose which is insoluble in an organic solvent, the binder in the conductive material layer is dissolved in an organic solvent such as N-methyl-2-pyrrolidone in the positive electrode mixture paste, and the conductive material layer is made of metal. Separation from the current collector is prevented, and a positive electrode plate having good adhesion between the metal current collector and the conductive material layer is obtained. By using this positive electrode plate, a non-electrode having excellent high-rate discharge performance is obtained. A water electrolyte secondary battery can be provided.

Further, when the amount of carboxymethylcellulose added is 0.5 to 5% by weight based on the total weight of the conductive material layer, a battery having more excellent high-rate discharge performance can be provided. If the content of carboxymethylcellulose is less than 0.5 wt%, the adhesion between the conductive material layer and the metal current collector is insufficient, and conversely, the content of carboxymethylcellulose is low. 5
If the content is more than wt%, the ratio of carboxymethylcellulose, which is an insulator, in the conductive material layer becomes too large, and the current collecting property is greatly reduced. Therefore, the addition amount of carboxymethylcellulose is desirably 0.5 to 5 wt%.

Further, the conductive material is preferably a carbon material. The reason is that when a conductive material such as metal particles is used, the adhesion between the metal particles in the conductive material layer and the binder is inferior, and the charging and discharging of the metal particles due to the dissolution and deposition of the battery accompanying charging and discharging of the battery is performed. On the other hand, a carbon material may have a good adhesion to a foil and good electron conductivity, but may not cause a dissolution / precipitation reaction or the like, while a high discharge rate may be reduced.

Further, as the carbon material used as the conductive material, it is desirable to use graphite having high electron conductivity. In the case of flake graphite,
Since the graphite surface and the foil surface are oriented in a parallel direction, it is desirable in that the adhesion to the metal current collector is further improved.

Further, the thickness of the conductive material layer is 1 μm to 5 μm.
μm is desirable. When the current collector is provided with a conductive material layer and a positive electrode material mixture layer on both surfaces, the thickness of the conductive material layer indicates the thickness of one surface.

The reason why the thickness of the conductive material layer is preferably 1 μm to 5 μm is that when the thickness of the conductive material layer is smaller than 1 μm, the thickness of the conductive material layer between the positive electrode mixture layer and the conductive material layer is reduced. When it is larger than 5 μm, the thickness of the conductive material layer occupying the positive electrode plate is too large, so that the amount of the positive electrode active material mixture is reduced and the energy density of the battery is reduced.

The conductive material layer was applied to the metal current collector by gravure printing on the metal current collector. In addition, comma roll coating, offset printing,
It can also be performed by gravure printing, impregnation of a metal current collector in a conductive material paste, or the like, but is not particularly limited to these coating methods.

[0023] Incidentally, for use in non-aqueous electrolyte secondary battery of the present invention, as the positive electrode material serving as capable of absorbing and desorbing lithium compounds, as the inorganic compound, composition formula LixMO _2, or LiyM ₂ O ₄ (wherein M is Transition metal, 0 ≦ x ≦
1, 0 ≦ y ≦ 2), oxides having tunnel-like vacancies, and metal chalcogenides having a layered structure can be used. As a specific example, LiCo
O ₂ , LiNiO ₂ , LiMn ₂ O ₄ , Li ₂ Mn ₂ O ₄ ,
MnO ₂ , FeO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , TiS
_{And the} like. Examples of the organic compound include a conductive polymer such as polyaniline. Further, the above-mentioned various active materials may be mixed and used regardless of an inorganic compound or an organic compound.

Further, as a compound as a negative electrode material, A
alloys of lithium with l, Si, Pb, Sn, Zn, Cd, etc., transition metal oxides such as LiFe ₂ O ₃ , WO ₂ , MoO ₂ , graphite, carbonaceous materials such as carbon, Li
Lithium nitride such as ₅ (Li ₃ N), or metallic lithium foil, or a mixture thereof may be used.

The electrolyte solvent used for the nonaqueous electrolyte battery according to the present invention includes ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide. , 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran,
A polar solvent such as 2-methyltetrahydrofuran, dioxolan, methyl acetate, or a mixture thereof may be used.

Lithium salts dissolved in an organic solvent include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiAs
F ₂ , LiCF ₃ CO ₂ , LiCF ₃ SO ₃ , LiN (SO ₂
CF ₃ ) ₂ , LiN (SO ₂ CF ₂ CF ₃ ) ₂ , LiN (CO
Salts such as CF ₃ ) ₂ and LiN (COCF ₂ CF ₃ ) ₂ or mixtures thereof may be used.

The separator of the non-aqueous electrolyte battery according to the present invention may be a material obtained by impregnating an electrolytic solution in an insulating polyethylene microporous membrane, a solid polymer electrolyte, or a solid polymer electrolyte containing an electrolytic solution. A gel electrolyte or the like can also be used. Further, an insulating microporous film and a solid polymer electrolyte may be used in combination. Furthermore, when a porous solid polymer electrolyte membrane is used as the solid polymer electrolyte, the electrolyte contained in the polymer and the electrolyte contained in the pores may be different.

The shape of the battery is not particularly limited, and the present invention is applicable to non-aqueous electrolyte secondary batteries having various shapes such as a square, an ellipse, a coin, a button, and a paper battery. It is.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments to which the present invention is applied will be described. However, the present invention is not limited to the embodiments, and may be carried out by appropriately changing the scope of the present invention. Is possible.

Example 1 FIG. 1 is a schematic sectional view of a prismatic nonaqueous electrolyte secondary battery used in this example.

In FIG. 1, 1 is a non-aqueous electrolyte secondary battery,
2 is an electrode group, 3 is a positive electrode, 4 is a negative electrode, 5 is a separator, 6
Is a battery case, 7 is a lid, 8 is a safety valve, 9 is a positive electrode terminal, 1
0 is a positive electrode lead.

In this prismatic nonaqueous electrolyte secondary battery 1, a conductive material layer is provided on an aluminum foil serving as a positive electrode current collector, and a positive electrode containing a material capable of occluding and releasing lithium ions is provided on the conductive material layer. A positive electrode 3 formed by applying an agent and a negative electrode 4 formed by applying a negative electrode mixture containing a substance capable of inserting and extracting lithium ions to a copper current collector are wound via a separator 5. The flat electrode group 2 and a nonaqueous electrolyte containing an electrolyte salt are housed in a battery case 6.

A battery lid provided with a safety valve 8 is attached to the battery case 6 by laser welding, the negative electrode 4 is electrically connected to the inner wall of the battery case 6 by contact, and the positive terminal 9 is connected via a positive lead 10. It is connected to the positive electrode 3.

FIG. 2 is a schematic sectional view of the positive electrode plate used in the embodiment. In FIG. 2, 11 is an aluminum foil, 12 is a conductive material layer, and 13 is a positive electrode mixture.

The conductive material layer 12 is made of a conductive material paste prepared by mixing 95% by weight of graphite as a conductive material and 5% by weight of carboxymethylcellulose (CMC) as a binder and appropriately adding purified water to disperse. With a thickness of 20μ
m, is uniformly coated on both sides of an aluminum foil current collector 11 as a positive electrode current collector by gravure printing, dried, and then compression-molded by a roll press, so that the thickness of the conductive material paste is 5 μm per side. It was manufactured so that it might become.

The positive electrode mixture 13 contains LiCoO ₂ 8 as an active material.
7% by weight, 5% by weight of acetylene black as a conductive material,
8 wt% of polyvinylidene fluoride (PVdF) as a binder was mixed, and N-methyl-2-pyrrolidone was appropriately added and dispersed to prepare a positive electrode mixture paste. This paste was uniformly applied on the above-mentioned positive electrode current collector, dried, and then compression-molded to a thickness of 180 μm by a roll press to produce a positive electrode 3.

The negative electrode mixture was composed of 90% by weight of a carbon material capable of inserting and extracting lithium ions, and polyvinylidene fluoride (PVd).
F) 10 wt% was mixed and N-methyl-2-pyrrolidone was appropriately added and dispersed to prepare a negative electrode mixture paste.
This paste is uniformly applied to a 10 μm thick copper current collector,
After drying, the negative electrode 4 was produced by compression molding with a roll press to a thickness of 180 μm.

As the separator, a microporous polyethylene film having a thickness of 25 μm was used. As a non-aqueous electrolyte,
Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 1: 1 and an electrolytic solution in which LiPF ₆ was dissolved at 1.0 mol / l as an electrolyte salt was used.

According to the above-described components and procedures, the first embodiment having the external dimensions of 48 mm in height, 22 mm in width, and 8 mm in thickness was used.
10 batteries were produced.

Example 2 In Example 2, 99.5 wt% of graphite as a conductive material and 0.5 wt% of carboxymethyl cellulose (CMC) as a binder were mixed, and purified water was added as appropriate. It was dispersed to prepare a conductive material paste. Except for the conductive material paste, ten batteries of Example 2 were produced using the components and procedures described in Example 1.

Example 3 As Example 3, 95% by weight of carbon black as a conductive material and 5% by weight of carboxymethyl cellulose (CMC) as a binder were mixed, and purified water was appropriately added and dispersed. The conductive material paste was adjusted. Except for the conductive material paste, ten batteries of Example 3 were manufactured using the components and procedures described in Example 1.

Example 4 As Example 4, a conductive material paste was uniformly applied on both sides of a 20-μm-thick aluminum foil current collector, dried, and then compression-molded by a roll press to obtain a thickness. A positive electrode current collector having a 1 μm conductive material layer on one side was obtained. Except for the thickness of the conductive material layer, ten components of Example 4 were manufactured using the components and procedures described in Example 1.

Example 5 As Example 5, 95% by weight of stainless steel fine particles as a conductive material and 5% by weight of carboxymethylcellulose (CMC) as a binder were mixed, and purified water was appropriately added and dispersed. Then, the conductive material paste was adjusted. Except for the conductive material paste, ten batteries of Example 5 were manufactured using the components and procedures described in Example 1.

Comparative Example 1 As Comparative Example 1, 95% by weight of graphite as a conductive material and 5% by weight of polyvinylidene fluoride (PVdF) as a binder were mixed, and N-methyl-2-pyrrolidone was added as appropriate. And the conductive material paste was adjusted. Except for the conductive material paste, ten components of Comparative Example 1 were manufactured using the components and procedures described in Example 1.

Comparative Example 2 As Comparative Example 2, 95% by weight of graphite as a conductive material and 5% by weight of polymethyl methacrylate (PMMA) as a binder were mixed, and N-methyl-2-pyrrolidone was appropriately added. In addition, it was dispersed to prepare a conductive material paste. Except for the conductive material paste, ten components of Comparative Example 2 were produced using the components and procedures described in Example 1.

Comparative Example 3 As Comparative Example 3, 90% by weight of graphite as a conductive material and 10% by weight of carboxymethyl cellulose (CMC) as a binder were mixed.
Purified water was appropriately added and dispersed to prepare a conductive material paste. Except for the conductive material paste, ten components of Comparative Example 3 were manufactured using the components and procedures described in Example 1.

Comparative Example 4 As Comparative Example 4, 99.9% by weight of graphite as a conductive material and 0.1% by weight of carboxymethyl cellulose (CMC) as a binder were mixed, and purified water was added as appropriate. It was dispersed to prepare a conductive material paste. Except for the conductive material paste, ten components of Comparative Example 4 were produced using the components and procedures described in Example 1.

Comparative Example 5 As Comparative Example 5, a conductive material paste was uniformly applied on both sides of a 20-μm-thick aluminum foil current collector, dried, and then compression-molded by a roll press to obtain a thickness. Obtained a positive electrode current collector provided with a conductive material layer of 8 μm on one side. Except for the thickness of the conductive material layer, ten components of Comparative Example 5 were produced using the components and procedures described in Example 1.

Comparative Example 6 As Comparative Example 6, a conductive material paste was uniformly applied on both sides of a 20 μm-thick aluminum foil current collector, dried, and then compression-molded by a roll press to obtain a thickness. Obtained a positive electrode current collector provided with a 0.5 μm conductive material layer on one side. Except for the thickness of the conductive material layer, ten components of Comparative Example 6 were produced using the components and procedures described in Example 1.

With respect to the prismatic nonaqueous electrolyte secondary batteries of Examples and Comparative Examples produced as described above, the adhesion, the initial capacity, and the high efficiency of the positive electrode mixture layer and the metal current collector after the positive electrode mixture was applied. The capacity at the time of discharge and the capacity ratio at the time of high rate discharge were investigated.

Regarding the adhesion between the positive electrode mixture layer and the metal current collector after applying the positive electrode mixture, the positive electrode mixture paste is applied, dried, and then adhered to the surface of the positive electrode mixture with an adhesive tape. The tape was peeled off, and the degree of peeling of the positive electrode mixture from the metal current collector was observed.

Regarding the initial capacity of the battery, the charging voltage
After charging for 3 hours under the conditions of 20 V and a charging current of 600 mA, the discharge capacity was measured when discharging was performed under the conditions of a discharging current of 600 mA and a final voltage of 2.75 V.

Regarding the high rate discharge performance, the discharge current was 18
The measurement was performed under the same conditions as the measurement of the initial capacity except that the current was set to 00 mA, and the capacity at the time of high-rate discharge was obtained.

The capacity ratio at the time of high-rate discharge is a ratio obtained by dividing the capacity of each battery at the time of high-rate discharge (at the time of 1800 mA discharge) by the initial capacity of each battery (at the time of 600 mA discharge). . In Table 1, CMC indicates carboxymethyl cellulose, PVdF indicates polyvinylidene fluoride, and PMMA indicates polymethyl methacrylate.

Table 1 shows an outline of the batteries of the examples and the comparative examples.

[0056]

[Table 1]

Table 2 shows the results of investigation on the adhesion between the positive electrode mixture layer and the metal current collector, the initial capacity, the capacity at high rate discharge, and the capacity ratio at high rate discharge.

[0058]

[Table 2]

Next, the results of these tests will be described. First, the type of the binder in the conductive material layer was examined. Table 2 shows that the battery of Example 1 using carboxymethylcellulose as the binder for the conductive material layer was the battery of Comparative Example 1 using polyvinylidene fluoride as the binder, and the polymethacrylic acid as the binder. Compared with the battery of Comparative Example 2 using methyl, the adhesion between the conductive material layer and the metal foil was good, the capacity at the time of high-rate discharge was large, and the high-rate discharge performance was excellent.

Therefore, by using carboxymethylcellulose, which is insoluble in an organic solvent, as the binder of the conductive material layer, even after the positive electrode mixture paste is applied from above the conductive material layer, the metal collection It was found that a battery provided with a positive electrode plate having good adhesion between the conductor and the conductive material layer could be manufactured.

Next, the upper and lower limits of the amount of carboxymethylcellulose were examined. According to Table 2, the amount of carboxymethylcellulose in the conductive material layer was 10 wt.
% Of the battery of Comparative Example 3 had a lower capacity at the time of high-rate discharge than the battery of Example 1 having the same addition amount of 5 wt%.

From this fact, if the ratio of carboxymethylcellulose as the insulator in the conductive material layer is too large, the current collecting property in the conductive material layer of the positive electrode plate is reduced. It was found that by suppressing this, a battery having good current collection properties between the metal current collector and the conductive material layer and having excellent high-rate discharge performance could be produced.

Further, as shown in Table 2, the battery of Example 2 in which the addition amount of carboxymethylcellulose in the conductive material layer was 0.5 wt%, and Comparative Example 4 in which the addition amount of carboxymethyl cellulose was 0.1 wt%
As compared with the battery of the above, the adhesion between the conductive material layer and the metal foil is good, the capacity at the time of high-rate discharge is large, and the high-rate discharge performance is excellent.

From the above, by setting the amount of carboxymethylcellulose, which is a binder for the conductive material layer, to be 0.5 wt% or more, good adhesion between the metal current collector and the conductive material layer can be obtained. It was found that a battery including a positive electrode plate could be manufactured.

Next, the type of conductive material was examined. According to Table 2, the battery of Example 5 in which the conductive material in the conductive material layer was stainless particles had good peeling test results, a large discharge capacity during high-rate discharge, and excellent high-rate discharge performance. .

Further, the battery of Example 3 in which the conductive material in the conductive material layer was carbon black exhibited better high-rate discharge performance than the battery of Example 5 using stainless steel particles as the conductive material. Furthermore, the battery of Example 1 in which the conductive material in the conductive material layer was graphite had better peel test results than the battery of Example 3 using carbon black as the conductive material, The capacity was large and the high rate discharge performance was excellent.

Thus, when stainless steel particles are used as the conductive material in the conductive material layer, a positive electrode plate having good adhesion between the metal current collector and the conductive material layer is provided, and high-rate discharge performance is excellent. It was found that a battery could be manufactured.

Further, by using a carbon material such as carbon black as the conductive material, a positive electrode plate having better adhesion between the metal current collector and the conductive material layer is provided, and higher discharge performance is achieved. It was found that an excellent battery could be manufactured. In addition, it was found that, by using graphite as the conductive material, it was possible to manufacture a battery having a positive electrode plate having better adhesion between the metal current collector and the conductive material layer and having a higher rate of discharge performance. .

Next, the upper and lower limits of the thickness of the conductive material were examined. According to Table 2, the battery of Example 1 in which the thickness of the conductive material layer was 5 μm had a larger initial capacity than the battery of Comparative Example 5 in which the thickness was 8 μm, but there was no significant difference in the high-rate discharge performance. . From this, the thickness of the conductive material layer was set to 5 μm
It was found that by controlling the content to be below, a battery including a positive electrode plate having a large initial capacity while having excellent high-rate discharge performance can be manufactured.

From Table 2, it can be seen that the thickness of the conductive material layer is 1 μm.
The battery of Example 4 has a good adhesion between the metal current collector and the conductive material layer although the initial capacity is slightly inferior to the battery of Comparative Example 6 having the same thickness of 0.5 μm. And excellent high rate discharge performance. From this fact, by setting the thickness of the conductive material layer to 0.5 μm or more, a battery provided with a positive electrode plate having good adhesion between the metal current collector and the conductive material layer and having excellent high-rate discharge performance Can be produced.

In this embodiment and the experimental example, an aluminum foil was used as the metal current collector of the positive electrode. However, the metal current collector is not particularly limited to the aluminum foil.

Although polyvinylidene fluoride is used as the binder for the positive electrode mixture paste, the present invention does not limit the binder of the positive electrode mixture paste to polyvinylidene fluoride.

[0073]

As is clear from the above description, by including carboxymethylcellulose in the conductive material layer as in the present invention, good adhesion between the metal current collector and the conductive material layer can be obtained. A battery having a positive electrode plate and excellent in high-rate discharge performance can be manufactured.

Further, the amount of carboxymethylcellulose added to the conductive material layer relative to the total weight of the conductive material layer is set to 0.5 to 5% by weight, so that the adhesion between the positive electrode mixture layer and the metal current collector is improved. It is possible to produce a battery having a positive electrode plate with even better performance and further excellent high-rate discharge performance.

Further, in the conductive material layer, by using a carbon material as the conductive material, a positive electrode plate having more favorable adhesion between the positive electrode mixture layer and the metal current collector is provided.
In addition, it is possible to produce a battery having an excellent high-rate discharge performance, and further, by using graphite as a carbon material, a positive electrode plate having more favorable adhesion between the positive electrode mixture layer and the metal current collector can be obtained. It is possible to produce a battery having the same and further excellent high-rate discharge performance.

Further, the thickness of the conductive material layer is set to 1 μm to 5 μm.
By so doing, it is possible to provide a positive electrode plate having more favorable adhesion between the positive electrode mixture layer and the metal current collector, to produce a battery having excellent high-rate discharge performance and a large initial capacity.

[Brief description of the drawings]

FIG. 1 is a view showing a longitudinal section of a prismatic nonaqueous electrolyte secondary battery of the present invention.

FIG. 2 is a diagram showing a cross section of a positive electrode plate of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-aqueous electrolyte secondary battery 2 Electrode group 3 Positive electrode 4 Negative electrode 5 Separator 6 Battery case 7 Lid 8 Safety valve 9 Positive electrode terminal 10 Positive electrode lead 11 Aluminum foil 12 Conductive material layer 13 Positive electrode mixture

Continued on the front page F term (reference) 5H029 AJ02 AK03 AK05 AK16 AK18 AL01 AL03 AL06 AL07 AL08 AL12 AL18 AM02 AM03 AM04 AM05 AM07 BJ02 BJ14 DJ07 DJ08 EJ04 EJ11 HJ01 HJ04 5H050 AA02 BA16 BA17 CA05 CA08 CA09 CB CB CA22 CB CB09 CB12 CB29 DA02 DA04 DA10 DA11 EA08 EA09 EA21 FA05 HA01 HA04

Claims (5)

[Claims] 1. A non-aqueous electrolyte comprising a conductive material layer containing a conductive material and a binder between a positive electrode mixture and a metal current collector, wherein the binder contains carboxymethyl cellulose. Rechargeable battery. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the amount of carboxymethylcellulose added is 0.5 to 5 wt% based on the total weight of the conductive material layer. 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the conductive material is a carbon material. 4. The non-aqueous electrolyte secondary battery according to claim 3, wherein the carbon material is graphite. 5. The non-aqueous electrolyte secondary battery according to claim 1, wherein the conductive material layer has a thickness of 1 μm to 5 μm.