JPH10188952A - Electrode for battery and battery using the electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the charge and discharge repeating characteristic of an electrode, and provide a battery having an excellent cycle characteristic by forming thickness of an end of an electrode mix layer larger than the mean thickness of the electrode mix layer without providing a projecting part. SOLUTION: From points of easiness of manufacture and control of thickness accuracy, an adhesive tape 22 is stuck onto a collector 21 of an electrode so as to increase the thickness of an end of a mix layer of a rectangular electrode (A). Electrode mix 22 is applied thereon, and after drying it, the adhesive tape 22 is peeled together with the mix 23 provided thereon (B). As a result, an electrode mix layer 24 to be obtained has a part 27, of which thickness is larger than the mean thickness of the electrode mix layer 24 (C). Maximum thickness of the thick part 27 of this end is increased at 2-25% in relation to the mean thickness of the electrode mix layer 24. Thickness can be adjusted by adjusting thickness of the tape 22. In this case, the part 27 is desirably not provided with a projecting part at an acute angle, and in the case where a projecting part is generated, it is mechanically scraped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode capable of achieving excellent battery performance, and more particularly to an electrode having excellent repetitive charge / discharge characteristics and a non-aqueous electrolyte secondary battery using the same.

[0002]

2. Description of the Related Art A secondary battery is frequently used as a power source of electronic equipment due to its high performance, miniaturization, and portability. In particular, recently developed lithium batteries are rapidly increasing in demand as power supplies for portable devices because of their high capacity and large output. However, it is known that the capacity of a secondary battery gradually decreases when charge and discharge are repeated.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of these circumstances, and it has been found that the electrode ends have a high potential, and the capacity gradually decreases due to the potential after a cycle. Reached.

An object of the present invention is to provide an electrode having excellent repetitive charge / discharge characteristics and to provide a non-aqueous electrolyte secondary battery having excellent cycle characteristics using these electrodes.

[0005]

An object of the present invention is to provide a rectangular electrode having at least one electrode mixture layer on a current collector, wherein a maximum thickness of at least one end of the electrode mixture layer is provided. Is 2% to 25% thicker than the average thickness of the electrode mixture layer,
The problem has been solved by an electrode characterized by having no projection.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention include the following, but the present invention is not limited thereto.

(1) In a rectangular electrode having at least one electrode mixture layer on a current collector, the maximum thickness of at least one end of the electrode mixture layer is larger than the average thickness of the electrode mixture layer. Characterized by having a thickness of 2% to 25% and no protrusions.

(2) The distance L between the peak position of the portion thicker than the average thickness of the electrode mixture layer and the end of the electrode mixture layer is 5 mm.
Item 2. The electrode according to Item 1, wherein

(3) The distance L between the peak position of the portion thicker than the average thickness of the electrode mixture layer and the end of the electrode mixture layer is 2.5.
Item 1. The electrode according to Item 1, which is within mm.

(4) When the cross section of the electrode mixture layer rises perpendicularly from the end of the electrode mixture layer and approximates to a rectangle having a height equal to the average thickness, the electrode mixture at the end outside the rectangle is formed. (2) The area (S1) of the portion of the material layer is 0.5 times or more and 5 times or less the area (S2) of the portion without the electrode mixture layer, which is included inside the rectangle at the end. 4. The electrode according to 3.

(5) When the cross section of the electrode mixture layer is approximated to a rectangle, the area S1 of the part outside the rectangle at the end and the part of the electrode mixture layer is the part inside the rectangle. Item 2 or 3 wherein the area S2 is 0.8 times or more and 1.2 times or less the area S2 of the portion without the electrode mixture layer.
The electrode according to 1.

(6) When the curvature (radius) at the peak of the electrode mixture layer is d, where d is the average thickness of the electrode mixture layer,
Item 6. The electrode according to any one of Items 1 to 5, wherein the electrode size is not less than (1/8) × d and not more than 4 × d.

(7) When the average thickness of the electrode mixture layer is d, the curvature (radius) of the peak portion of the electrode mixture layer is:
Item 6. The electrode according to any one of Items 1 to 5, which is equal to or more than (１ ／) × d and equal to or less than d.

(8) The method according to any one of items 1 to 7, wherein a boundary between an end of the electrode mixture layer and a surface of the current collector is substantially perpendicular to a longitudinal direction of the rectangular electrode. The electrode as described.

(9) At least one-third of the entire width of the electrode mixture layer is 2% to 25% thicker than the average thickness of the electrode mixture layer, and the end of the electrode mixture layer has a protrusion. Item 8. The electrode according to any one of Items 1 to 7, wherein the electrode is not provided.

(10) The average thickness of the electrode mixture layer is 30 μm.
Item 10. The electrode according to any one of Items 1 to 9, wherein the electrode has a length of not less than m and not more than 400 μm.

(11) The electrode according to item 10, wherein the electrode mixture layer comprises a positive electrode mixture for a lithium battery.

(12) The positive electrode mixture is used as a positive electrode active material,
Li_xCoO_Two , Li_xNiO_Two , Li_xCo_aNi
_1-aO_Two , Li_xCo_bV_1-bO_z, Li_xCo_bFe
_1-bO _z, Li_xMn_Two O_Four , Li_xMnO_Two , Li_x
Mn_Two O_Three , Li_xMn_bCo _2-bO_z, Li_xMn_b
Ni_2-bO_z, Li_xMn_bV_2-bO_z, Li_xMn_b
Fe_1-bO_z(Where x = 0.05-1.2, a = 0.
1-0.9, b = 0.8-0.98, z = 1.5-5)
Having at least one member selected from the group consisting of
Item 12. The electrode according to item 11, wherein

(13) A battery using the electrode according to any one of items 1 to 12.

(14) A sheet-shaped positive electrode obtained by applying a positive electrode mixture on a positive electrode current collector, a sheet-shaped negative electrode obtained by applying a negative electrode mixture on a negative electrode current collector, and a microporous material A non-aqueous electrolyte secondary battery obtained by winding a separator, wherein the positive electrode and the negative electrode are the electrodes according to any one of Items 1 to 10, and the length and width of the positive electrode mixture adhering portion are the negative electrode A non-aqueous electrolyte secondary battery having a length smaller than a length and a width of a portion where a mixture is attached.

Hereinafter, embodiments of the present invention will be described in detail. In the present specification, the thickness of the electrode mixture layer is thick,
In a thick portion, it means that the amount of a substance involved in an electrode reaction (a substance capable of inserting and releasing a positive electrode active material for a positive electrode and lithium or the like for a negative electrode) is large. In the press after the electrode coating and drying, the thickness of the end portion can be increased by changing the pressing pressure of the center portion and the end portion, but in this case, the applied amount of the substance involved in the electrode reaction itself is the average thickness. Because it is not different from the part, "thick" referred to in this specification
It does not have a thickness.

The rectangular electrode can be manufactured as follows. An electrode mixture containing a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives in addition to an active material or an electrode material that is a precursor thereof is placed on a current collector such as a metal foil. Installed in

In order to place the electrode mixture on the current collector, a method such as a coating method or a press of a compression-molded mixture is used. As a coating method, a general method can be used. For example, there can be mentioned a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method and a squeeze method.

Among them, the blade method, the knife method and the extrusion method are preferred. The coating may be performed on one side at a time or on both sides simultaneously.

The coating may be continuous, intermittent, or striped. The thickness, length and width of the coating layer are determined according to the size of the battery, and the thickness of the coating layer on one side is particularly preferably 1 to 2000 μm in a compressed state after drying.

A rectangular electrode can be obtained by appropriately cutting the electrode thus obtained. Any of the following methods may be applied as a method for increasing the thickness of the end of the mixture layer of the rectangular electrode. An example of a method for increasing the thickness of the end will be described.

A method of mechanically shaping the shape. For example, a method in which a portion of the mixture layer having a uniform thickness is cut out for an electrode, and a center portion excluding an end portion is cut off with a grinder or the like. A method in which the coating liquid is brought to the edge by wind pressure or the like between application and drying.

A method in which only the ends are repeatedly applied. For example,
A method of applying stripe coating or screen printing to the edge of an electrode having a uniform thickness.

A method in which the shape of the slot for extrusion application or the like is not uniform, but the end is enlarged to increase the extrusion flow rate at the end.

A method of adjusting the flow rate at the time of attaching and detaching the coater to adjust the end thickness in the coating direction.

A method for adjusting physical properties of a coating solution. For example, a method in which a liquid having a high thixotropy is used and the front and rear ends of the coating at the time of intermittent coating are thickened.

After coating, a method of forming a thick portion at the boundary of the remaining portion by removing the end portion.

A method in which a mixture layer is applied on a substrate having a step, a gentle mixture layer gradient is formed near the step, and the upper part of the step is removed. This method will be described later with reference to FIGS.
This will be described in detail with reference to FIG. And the like.

Among the above methods, the above method is preferable from the viewpoint of easiness of the manufacturing process and control of thickness accuracy.
1A to 1C show specific examples. FIG. 1 (A)
As shown in FIG. 1, an adhesive tape 22 is attached on a current collector 21 of an electrode, for example. Next, as shown in FIG.
An electrode mixture 23 is applied from above, and after drying, the adhesive tape 22 is peeled off together with the mixture 23 thereon. As shown in FIG. 1C, the electrode mixture layer 24 has a portion 27 at an end portion that is thicker than the average thickness. In the case of this method, the thickness of the portion 27 thicker than the average thickness of the electrode mixture layer 24 is
The thickness can be adjusted by the thickness.

The adhesive tape 22 functions as a so-called masking tape, and is formed by forming a resin material such as a polyolefin such as polyethylene and polypropylene, a polyester such as polyvinyl chloride and polyethylene terephthalate into a tape shape. . An adhesive layer is provided on one surface of the tape 22. Various kinds of pressure-sensitive adhesives are already known, and they can be used without any particular limitation. However, it is desirable that the adhesive has an appropriate adhesive strength so that it can be easily peeled off from the surface of the long conductive sheet 21 in the operation of peeling the adhesive tape 22. The adhesive strength is 180
5-100g /
Those in the range of 20 mm are suitable. Moreover, the adhesive strength of the adhesive is reduced by the heating temperature of the heating and drying step performed when the electrode mixture layer 23 is formed on the long current collector sheet 21 after the adhesive tape 22 is attached. It is preferable that it has a characteristic.

FIG. 2A is a sectional view of the electrode. An electrode mixture layer 24 is applied on the current collector 21. The end 26 of the electrode mixture layer 24 has a thickness peak 27. The thickness d0 of the peak 27 is preferably 2% to 25% thicker than the average thickness of the electrode mixture layer 24, and more preferably 5% to 20% thicker. When the center portion of the electrode mixture layer 24 except for the end portion 26 has a substantially uniform thickness, the electrode mixture layer 2
4 can be approximated to the average thickness d.

Peak position of thick part (thickest position) 2
The distance L between 7 and the position of the end 25 of the mixture layer is preferably within 5 mm, more preferably within 2.5 mm, particularly preferably within 1 mm. Here, the position of the end 25 of the mixture layer refers to a point at 5% of the average thickness d of the mixture layer. The skirt at the end of the mixture layer 24 may be short or long.

It is desirable that the area of the thick part is not too large. As shown in FIG. 2B, when the cross section of the electrode mixture layer 24 rises vertically from the end of the electrode mixture layer 24 and approximates a rectangle 31 having a height equal to the average thickness, the rectangle 31 at the end portion Area S1 of portion of mixture layer 24 on the outer side
Is preferably 0.5 to 5 times the area S2 of the part without the mixture layer 24, which is included inside the rectangle 31 at the end.
7-1.5 times is more preferable, and 0.8-1.2 times is particularly preferable.

It is preferable that a portion thicker than the average thickness d of the electrode mixture layer 24 does not have a sharp projection. The end formed by the method of peeling the adhesive tape described above often has a projection. Preferably, the protrusions are mechanically scraped off. In the scraping, even the method of shaving the mixture layer after drying,
A method of scraping from the mixture layer before drying may be used.

When there is no projection, when the portion having the area S1 in FIG. 2B is approximated as a triangle, when the angle of the peak on the mountain is 60 degrees or more, or when the surface of the current collector is When approximated to a plane, it refers to a case where the angle formed by one of the two sides forming the peak of the mountain with the surface of the current collector is 60 degrees or less. The thickness d0 of the peak 27 (FIG. 2)
(A) is 2% to 25% of the average thickness of the electrode mixture layer 24.
% Thick and has no projection.

The radius of curvature of the thick peak portion 27 is
When the average thickness of the electrode mixture layer is d, 1 /
It is preferably 8 to 4 times, more preferably 1/4 to 2 times, and 1
/ 2 to 1 times is particularly preferred.

FIG. 2C is a plan view of the electrode. An electrode mixture layer 24 is applied on the current collector 21. The boundary 34 between the coating end of the electrode mixture layer 24 and the surface of the current collector 21 is
The angle φ is substantially perpendicular to the longitudinal direction 32 of the rectangular electrode. Angle φ is preferably from 88 ° to 92 °. Electrode mixture layer 2
4 are not necessarily all the average thickness d across the width direction.
It need not be thicker, and thicker portions may be interspersed. The end of the electrode mixture layer 24 may have a thickness in a width direction at least 1/3 of the entire width 33 of the electrode mixture layer 24 that is greater than the average thickness d. Here, the width of the electrode mixture layer 24 is a length in a direction perpendicular to the longitudinal direction 32 of the electrode and on the surface of the current collector 21.

The electrode having the above shape can be applied to both the positive electrode and the negative electrode of a battery. In that case, it is preferable that the area of the negative electrode facing the positive electrode is larger than that of the positive electrode. The effect of the electrode according to the embodiment of the present invention will be described using a positive electrode using LiCoO ₂ as a positive electrode active material as an example. During charging, lithium ions move from the positive electrode to the negative electrode. At this time, since the area of the opposing negative electrode is larger at the end of the positive electrode, a larger amount of lithium ions move toward the negative electrode than at the center of the positive electrode. Therefore, if the active material at the center of the positive electrode during charging is expressed as Li _1-x CoO ₂ , the end of the positive electrode will be Li _1-xd CoO ₂ . d is the amount of lithium that has extraly moved from the end of the positive electrode to the negative electrode. LiCoO
_In the case of the positive electrode active material such as ₂ , if the amount of lithium extracted is too large, the crystal structure will collapse. Therefore, it is preferable that the variation in the amount of lithium extracted be small. The amount of lithium extracted from the positive electrode can be known by examining the potential of the positive electrode.

FIG. 3 shows the positive electrode potential (upper part in the figure) and the positive electrode end shape (lower part in the figure) with respect to the distance from the end of the positive electrode mixture layer.
FIG. 4 is a model diagram showing the relationship between the following. The dotted line b is an electrode in which the thickness of the end portion of the mixture layer is smaller than the average thickness. At the end portion, a large amount of lithium is extracted, so that the potential becomes high.
An alternate long and short dash line c indicates a case where the edge of the mixture layer is thick and has a sharp projection. Since the amount of lithium extracted from the end of the positive electrode is relatively smaller than that at the center, the potential at the end is lower than the reference potential. However, since the amount of lithium ions moving to the end of the negative electrode is larger than that in the central portion, it becomes more severe for the negative electrode, and in some cases, lithium dendrite is generated in the negative electrode, which causes a micro short circuit, which is not preferable. The solid line a shows the case where the above-described embodiment of the present invention has the end, and the positive electrode potential shows almost flat characteristics from the end to the vicinity of the center, which is preferable.

FIG. 4 is a sectional view of a cylinder type battery.
The shape of the battery can be applied to both cylinders and corners.
The battery is formed by inserting the electrode sheets 8 and 9 wound together with the separator 10 into the battery can 11, electrically connecting the battery can 11 and the negative electrode sheet 9, injecting the electrolyte 15, and sealing the battery. The battery lid 12 has a positive electrode terminal, and is fitted to the upper opening of the battery can 11 via a gasket. The electrode sheet 8
It is electrically connected to the battery lid 12. At this time, safety valve 14
Can be used as a sealing plate. Further, it is preferable to use a PTC (positive temperature coefficient) element 16 in order to guarantee the safety of the battery.

The electrode sheet (sheet-like electrode plate) applied by the above method is applied to all batteries using a rectangular electrode or an electrode sheet.
A non-aqueous secondary battery using lithium as an active material will be described in detail. The positive and negative electrodes used in non-aqueous secondary batteries are formed by applying the positive electrode mixture or the negative electrode mixture on a current collector (also serving as a support) and molding using the above-mentioned extrusion type liquid injector. be able to. The positive electrode or negative electrode mixture may contain a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives, respectively, in addition to the positive electrode active material or the negative electrode material. The electrode is prepared by applying the mixture on the current collector, then drying, dehydrating, and pressing.

The active material in the positive electrode can insert and release light metals.
Any material may be used, but preferably lithium-containing transition gold
Oxides, more preferably Li_xCoO_Two , Li
_xNiO_Two , Li_xCo_aNi_1-aO_Two , Li_xCo_b
V_1-bO_z, Li_xCo_bFe_1-bO_z, Li_xMn_Two 
O_Four , Li_xMnO_Two , Li_xMn_Two O_Three , Li_xMn
_bCo_2-bO_z, Li_xMn_bNi_2-bO_z, Li_xM
n_bV_2-bO_z, Li _xMn_bFe_1-bO_z(Where x
= 0.05-1.2, a = 0.1-0.9, b = 0.8
0.98, z = 1.5 to 5).

Hereinafter, the term “light metal” as used herein refers to an element belonging to Group 1A (excluding hydrogen) and Group 2A of the periodic table, preferably lithium, sodium and potassium, and particularly lithium. Is preferred.

The active material in the negative electrode may be any material capable of inserting and releasing a light metal, and is preferably graphite (natural graphite, artificial graphite, vapor-grown graphite), coke (coal or petroleum), or a baked product of an organic polymer. (Resin or fiber of polyacrylonitrile, furan resin, cresol resin, phenol resin), mesophase pitch fired product, metal oxide, metal chalcogenide, lithium-containing transition metal oxide and chalcogenide.

In particular, Ge, Sn, Pb, Bi, Al, G
Oxides and chalcogenides composed of a, Si, and Sb alone or in combination are preferable. Furthermore, SiO ₂ , B ₂ O ₃ , which are known as network formers,
Those made amorphous by adding P ₂ O ₅ , Al ₂ O ₃ , V ₂ O ₅ or the like are particularly preferable. These may be of stoichiometric composition or non-stoichiometric compounds.

Preferred examples of these compounds include, but are not limited to, the following.

GeO, GeO_Two , SnO, SnO_Two , S
nSiO_Three , PbO, SiO, Sb _Two O_Five , Bi_Two O
_Three , Li_Two SiO_Three , Li_Four Si_Two O₇ , Li_Two GeO
_Three , SnAl_0.4B_0.5P_0.5K_0.1O_3.65, SnAl
_0.4B_0.5P_0.5Cs_0.1O_{3. 65}, SnAl_0.4B_0.5
P_0.5K_0.1Ge_0.05O_3.85, SnAl_0.4B_0.5P_0.
FiveK_0.1Mg_0.1Ge_0.02O_3.83, SnAl_0.4B_0.4
P_0.4Ba_0.08O_3.28, SnAl_0.5B_0.4P_0.5Mg
_0.1F_0.2O_3.65, SnAl_0.4B_0.5P_0.5Cs_0.1
Mg_0.1F_0.2O_3.65, SnB_0.5P_0.5Cs_0.05Mg
_0.05F_0.1O_3.03, Sn_1.1Al_0.4B_0.4P_0.4Ba
_0.08O_3.34, Sn_1.2Al_0.5B_0.3P_{0. Four}Cs_0.2O
_3.5, SnSi_0.5Al_0.2B_0.1P_0.1Mg_0.1O
_2.8, SnSi_0.5Al_0.3B_0.4P_0.5O_4.30, Sn
Si_0.6Al_0.1B_0.1P_0.1Ba_{0. Two}O_2.95, SnS
i_0.6Al_0.4B_0.2Mg_0.1O_3.2, Sn_0.9Mn
_0.3B_{0. Four}P_0.4Ca_0.1Rb_0.1O_2.95, Sn_0.9F
e_0.3B_0.4P_0.4Ca_0.1Rb _0.1O_2.95, Sn_0.3
Ge_0.7Ba_0.1P_0.9O_3.35, Sn_0.9Mn_0.1Mg
_{0. 1}P_0.9O_3.35, Sn_0.2Mn_0.8Mg_0.1P_0.9O
_3.35

Further, a light metal, especially lithium, can be used as the negative electrode material. The method of inserting lithium is preferably an electrochemical, chemical or thermal method.

The amount of lithium inserted into the negative electrode material may be close to the lithium deposition potential, but is preferably 50 to 700 mol% per the above preferable negative electrode material. Especially 10
0-600 mol% is preferred.

The conductive agent in the positive electrode and the negative electrode is graphite, acetylene black, carbon black, Ketjen black, carbon fiber or metal powder, metal fiber or polyphenylene derivative, and graphite and acetylene black are particularly preferable.

The binders in the positive electrode and the negative electrode include polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl alcohol, starch, regenerated cellulose, diacetyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, Polyethylene, polypropylene,
SBR (styrene-butadiene-rub)
ber), ethylene-propylene-diene terpolymer (EPDM: ethylene-propylene-)
diene methylene linkage),
Sulfonated EPDM, fluororubber, polybutadiene and polyethylene oxide, and particularly preferred are polyacrylic acid, carboxymethylcellulose, polytetrafluoroethylene, and polyvinylidene fluoride. These are more preferably used as an aqueous dispersion latex having a particle size of 1 micron or less.

The support or current collector of the positive electrode and the negative electrode is made of aluminum, stainless steel, nickel, titanium, or an alloy thereof for the positive electrode.
Stainless steel, nickel, titanium, or an alloy thereof, in the form of foil, expanded metal, punched metal, or wire mesh. In particular, an aluminum foil is preferable for the positive electrode, and a copper foil is preferable for the negative electrode.

The separator may have a high ion permeability, a predetermined mechanical strength and an insulating thin film, and may be made of an olefin polymer, a fluorine polymer,
Cellulose polymer, polyimide, nylon, glass fiber, alumina fiber is used, as the form, non-woven fabric,
Woven fabrics and microporous films are used. In particular, the material is preferably polypropylene, polyethylene, a mixture of polypropylene and polyethylene, a mixture of polypropylene and Teflon, a mixture of polyethylene and Teflon, and the form is preferably a microporous film. Especially,
A microporous film having a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferred.

The electrolytic solution used as an organic solvent is propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate,
1,2-dimethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, dioxolan, 1,3-dioxolan, formamide, dimethylformamide, nitromethane, acetonitrile, methyl formate, methyl acetate, methyl propionate, Phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2
-Oxazolidinone, propylene carbonate derivative,
A mixture of at least one of a tetrahydro derivative, diethyl ether and 1,3-propane sultone, and LiClO ₄ , LiBF ₄ , LiPF
₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF
₆ , LiSbF ₆ , LiB ₁₀ Cl ₁₀ , lithium lower aliphatic carboxylate, LiAlCl ₄ , LiCl, LiBr,
It is preferable to dissolve at least one salt of LiI, lithium chloroborane, and lithium tetraphenylborate. Particularly, a mixed solvent of propylene carbonate or ethylene carbonate and 1,2-dimethoxyethane and / or diethyl carbonate is used in a mixture of LiCF ₃ SO ₃ and LiClO.
₄ , LiBF ₄ , and / or LiPF ₆ are preferably dissolved, and particularly preferably contain at least ethylene carbonate and LiPF ₆ .

The bottomed battery outer can is made of a nickel-plated iron or stainless steel plate (SUS30).
4, SUS304L, SUS304N, SUS316,
SUS316L, SUS430, SUS444, etc.), nickel-plated stainless steel plate (same as above), aluminum or its alloy, nickel, titanium, copper,
The shape is a true circular cylindrical shape, an elliptical cylindrical shape, a square cylindrical shape, or a rectangular cylindrical shape. In particular, when the outer can also serves as the negative electrode terminal, a stainless steel plate or a nickel-plated iron steel plate is preferable, and when the outer can also serves as the positive electrode terminal, a stainless steel plate, aluminum or an alloy thereof is preferable.

The gasket is made of an olefin polymer, a fluorine polymer, a cellulose polymer,
It is a polyimide or a polyamide, and is preferably an olefin-based polymer, particularly preferably a propylene-based polymer, in view of organic solvent resistance and low moisture permeability. Further, it is preferably a block copolymer of propylene and ethylene.

[0062] The battery is covered with an exterior material if necessary.
Examples of the exterior material include a heat-shrinkable tube, an adhesive tape, a metal film, paper, cloth, paint, a plastic case, and the like.
Further, at least a part of the exterior may be provided with a portion that changes color by heat so that the heat history during use can be recognized.

A plurality of batteries are assembled in series and / or in parallel as necessary and stored in the battery pack. In addition to safety elements such as positive temperature coefficient resistors, thermal fuses, fuses and / or current interrupting elements, battery packs have safety circuits (voltage, temperature, current, etc. of each battery and / or assembled battery as a whole, Then, a circuit having a function of interrupting the current may be provided. In addition to the positive and negative terminals of the whole battery pack, the positive and negative terminals of each battery, the temperature detection terminals of the whole battery pack and each battery, the current detection terminals of the whole battery pack, etc. shall be provided as external terminals on the battery pack. Can also. The battery pack may have a built-in voltage conversion circuit (such as a DC-DC converter). The connection of each battery may be fixed by welding a lead plate, or may be fixed by a socket or the like so that it can be easily detached. Further, the battery pack may be provided with a display function of the remaining battery capacity, the presence or absence of charging, the number of times of use, and the like.

The battery is used for various devices. In particular, video movies, portable VCRs with built-in monitors, movie cameras with built-in monitors, compact cameras, single-lens reflex cameras, disposable cameras, films with lenses, notebook computers, notebook word processors, electronic organizers, mobile phones,
Cordless phones, shavings, electric tools, electric mixers,
It is preferably used for automobiles and the like.

[0065]

The present invention will be described in more detail with reference to specific examples, but the present invention is not limited to the examples unless it exceeds the gist of the invention.

Example 1 A positive electrode was made of LiC as an active material.
oO ₂ (87 parts by weight), flake graphite (6 parts by weight) and acetylene black (3 parts by weight) as conductive agents, polytetrafluoroethylene aqueous dispersion (3 parts by weight) and polyacrylic as binders A slurry obtained by adding sodium acid (1 part by weight) and kneading with water as a medium is applied to both surfaces of an aluminum foil (current collector: thickness: 20 μm) by an extrusion method, and the applied material is dried. , Compression molding with a calender press machine, cutting, width 56m
A belt-shaped positive electrode (C having a length of 400 mm and a thickness of 250 μm)
-1) was obtained. In order to produce the end shape according to the embodiment of the present invention, a polypropylene adhesive tape (thickness 2) is perpendicular to the longitudinal direction of the aluminum foil (current collector) before application.
(0 μm to 50 μm) was applied to the end of the electrode, the tape was peeled off after application and drying, and the shape was physically adjusted with a grinder, followed by pressing. The shapes of the end portions of the obtained positive electrodes C-2 to C-10 are as shown in [Table 1].

[0067]

[Table 1]

The negative electrode was composed of tin monoxide (73.3 parts by weight), silicon dioxide (19.5 parts by weight), and magnesium oxide (3.10 parts by weight).
5 parts by weight) and boron oxide (3.7 parts by weight) were dry-mixed, baked in an argon atmosphere for 10 hours (1200 ° C.), and then cooled and pulverized to obtain Sn having an average particle size of 4.5 μm.
The _{Si 0. 6 Mg 0.2 B 0.2} O 2.7 was used as a negative electrode material. The negative electrode material (88 parts by weight), flake graphite (6 parts by weight) as a conductive agent, an aqueous dispersion of polyvinylidene fluoride (4 parts by weight) as a binder, carboxymethyl cellulose (1 part by weight), and acetic acid A slurry obtained by adding lithium (1 part by weight) and kneading using water as a medium is applied to both surfaces of a copper foil (current collector: thickness 18 μm) by an extrusion method, and dried and compression-molded in the same manner as the positive electrode. Then, a strip-shaped negative electrode (A-1) having a width of 58 mm, a length of 440 mm and a thickness of 78 μm was obtained.

Before cutting, a low humidity atmosphere (dew point: -5
(0 ° C.), the positive electrode C-1 and the negative electrode A-1 obtained above were dehydrated and dried (far infrared heater, 200 to 250 ° C., 2 hours). Thereafter, a lead plate made of nickel was ultrasonically welded to the uncoated portion of the negative electrode sheet. Further, a lead plate was ultrasonically welded to an exposed portion of the 20 μm-thick aluminum current collector of the positive electrode sheet. The base of the lead was protected by applying an adhesive tape using a silicone adhesive to the welded portion of the lead. As shown in FIG. 4, the obtained positive electrode sheet with lead (8), microporous polyethylene film separator (10), and negative electrode sheet (9) were wound by a winding machine.

This wound body was housed in a nickel-plated iron bottomed cylindrical battery can (11) also serving as a negative electrode terminal. LiPF ₆ and LiBF ₄ as electrolytes (15)
0.9 and 0.1 mol per liter, respectively.
The solvent is ethylene carbonate, dimethyl carbonate,
A mixed solution in which the volume ratio of diethyl carbonate and ethyl propionate was 2: 4: 3: 1 was injected into the battery can (11). The battery lid (12) having the positive electrode terminal was caulked via a gasket (13) to produce a cylindrical battery. The positive electrode terminal (12) was electrically connected to the positive electrode sheet (8) and the battery can (11) was previously electrically connected to the negative electrode sheet (9) by lead terminals. (14) is a safety valve. Battery D-1 was prepared in the manner described above.

Using the positive electrodes C-2 to C-11 and the negative electrode A-1 shown in Table 1 above, the battery D-
Nos. 2 to D11 were prepared. Using these batteries, 4.3V
After charging the battery, it was stored at 50 ° C. for one month. After saving,
Charged to 2.7V. The discharge capacity at this time is shown in Table 2 below. The discharge capacity was shown as a relative value to the battery D-5.

[0072]

[Table 2]

It was confirmed that the battery using the electrode of the present example had improved cycle characteristics as compared with the battery of the comparative example.

The positive electrode C-1 used for the battery D-1 had a thickness d excluding the edge of the mixture layer and a thickness d0 of the edge both of 250 μm.
And the film thickness is uniform. The positive electrodes C-2 to C-11 used for the batteries D-2 to D-11 had a thickness d0 at the end of the mixture layer.
Is thicker than the film thickness d excluding the end portions. Battery D-2 to D-11
Has a larger discharge capacity than the battery D-1. It is preferable that the thickness d0 at the end is larger than the thickness d (average thickness of the mixture layer) excluding the end because the discharge capacity is large.

The positive electrode C-11 used for the battery D-11 had a film thickness d0 (32) at the end compared to the other batteries D-2 to D-10.
0 μm) is thicker (28% thicker) than the film thickness d (250 μm) excluding the end portions, and the discharge capacity is small. The film thickness d0 at the end portion is 2% to 2% larger than the film thickness excluding the end portion (average thickness of the mixture layer) d.
Batteries D-2 to D-10 that are 5% thick have a large discharge capacity and are thus preferable. The film thickness d0 at the end is 2 times larger than the film thickness d excluding the end.
% To 25% and preferably have no projections.

The positive electrode C-3 used in the battery D-3 had a distance L to the peak position of 10 mm, and the other batteries D-4 to
The distance L is larger than D-10. Battery D-3 having a large distance L has a smaller discharge capacity than the other batteries D-4 to D-10, which is not preferable. Batteries D-4 to D-10 having a distance L of 5 mm or less have a large discharge capacity, and thus are preferable.

Assuming that the areas shown in FIG. 2B are S1 and S2, respectively, the performance of the battery differs depending on the magnitude of S1 / S2. Battery D-4 having S1 / S2 = 10 has
The discharge capacity is smaller than that of the battery D-5 in which S2 is 2. S
A battery having 1 / S2 of 0.5 to 5 has a large discharge capacity,
preferable.

The positive electrode C-2 used for the battery D-2 is different from the other batteries D-3 to D-10 in that the positive electrode C-2 has a protrusion at the end (small radius of curvature). Batteries D-3 to D-10 have a large radius of curvature near the peak at the end. Battery D-2 having protrusions
Has a smaller discharge capacity than other batteries D-3 to D-10, which is not preferable. Also, the radius of curvature is too large (5
d) Battery D-3 has a smaller discharge capacity than other batteries D-4 to D-10, which is not preferable. The radius of curvature near the peak is １ ／ to 4 of the film thickness excluding the end (average thickness of the mixture layer) d
The batteries D-4 to D-10 which are twice as large have a large discharge capacity,
preferable.

[0079]

According to the present invention, by using an electrode mixture layer having a thick end portion and an electrode having no protrusion, a non-aqueous secondary battery having excellent charge / discharge cycle characteristics and high productivity can be obtained. Obtainable.

[Brief description of the drawings]

FIG. 1 is a diagram showing a method for manufacturing an electrode.

FIGS. 2A and 2B are cross-sectional views of electrodes.
FIG. 2C is a plan view of the electrode.

FIG. 3 is a diagram illustrating a positive electrode potential and a shape of a positive electrode end portion with respect to a distance from an end portion of a positive electrode mixture layer.

FIG. 4 is a cross-sectional view of a cylindrical battery used in Examples.

[Explanation of symbols]

 Reference Signs List 8 positive electrode sheet 9 negative electrode sheet 10 separator 11 battery can 12 battery lid 13 gasket 14 safety valve 15 electrolyte 16 PTC element 21 current collector 22 tape 24, 24 mixture layer

Claims (9)

[Claims] In a rectangular electrode having at least one electrode mixture layer on a current collector, the maximum thickness of at least one end of the electrode mixture layer is larger than the average thickness of the electrode mixture layer. An electrode for a battery, which is 2% to 25% thick and has no protrusion. 2. The electrode according to claim 1, wherein a distance L between a peak position of a portion thicker than the average thickness of the electrode mixture layer and an end of the electrode mixture layer is within 5 mm. 3. The electrode mixture layer rising vertically from an end of the electrode mixture layer and approximating a rectangle having a height equal to the average thickness, wherein the electrode mixture layer is located outside the rectangle at the end. The area S1 of the layer portion is 0.5 times or more the area S2 of the portion that is included inside the rectangle at the end and has no electrode mixture layer,
3. The electrode according to claim 2, wherein the ratio is 5 times or less. 4. The current collector according to claim 1, wherein a boundary between an end of the electrode mixture layer and a surface of the current collector is substantially perpendicular to a longitudinal direction of the rectangular electrode. 4. The electrode according to any one of to 3 above. 5. The electrode according to claim 1, wherein the average thickness of the electrode mixture layer is 30 μm or more and 400 μm or less. 6. The electrode according to claim 5, wherein the electrode mixture layer comprises a positive electrode mixture for a lithium battery. 7. The method according to claim 7, wherein the positive electrode mixture is Li_x
CoO_Two , Li_xNiO_Two , Li_xCo_aNi_1-aO
_Two , Li_xCo_bV_1-bO_z, Li_xCo_bFe_1-bO
_z, Li_xMn_Two O_Four , Li_xMnO_Two , Li_xMn_Two 
O_Three , Li_xMn_bCo_2-bO_z, Li_xMn_bNi
_2-bO_z, Li_xMn_bV_2-bO_z, Li _xMn_bFe
_1-bO_z(Where x = 0.05-1.2, a = 0.1-
0.9, b = 0.8-0.98, z = 1.5-5)
Characterized by having at least one selected from the compound group
The electrode according to claim 6, wherein 8. A battery using the electrode according to claim 1. 9. A sheet-shaped positive electrode obtained by applying a positive electrode mixture on a positive electrode current collector, a sheet-shaped negative electrode obtained by applying a negative electrode mixture on a negative electrode current collector, and a microporous separator. A wound non-aqueous electrolyte secondary battery, wherein the positive electrode and the negative electrode are the electrode according to any one of claims 1 to 5, and the length and width of the positive electrode mixture adhering portion are the negative electrode A non-aqueous electrolyte secondary battery having a length smaller than a length and a width of a portion where a mixture is attached.