JPH10228930A - Electrode sheet and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode sheet having process fitness, which can reduce the generation of failure such as breaking of electrode in a manufacturing process of the electrode by providing a part, which is not coated with the electrode mix, on a collector of an electrode sheet to be coated with the electrode mix in both surfaces of a collector, and displacing each electrode mix coated end of the surface and the back surfaces from each other in the longitudinal direction of the electrode sheet in a specified dimension range. SOLUTION: At the time of manufacturing this electrode sheet, tapes 22a, 22b are stuck on an upper and a lower surfaces of an electrode collector 21 so as to be displaced from each other in the longitudinal direction. Electrode mix 23a, 23b are coated so as to cover the electrode collector 21 and the tapes 22a, 22b of the upper and the lower surfaces, and dried. Thereafter, the tapes 22a, 22b are separated, and pressing or the like is performed. Final displacement L1 of the electrode mix layers 25a, 25b from each other in the longitudinal direction is set at 0.3-30mm. With this displacement, a trouble such as breaking of electrode by pressing and unevenness of winding can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention improves the productivity,
The present invention also relates to a technique for coating an electrode sheet which can be used for a non-aqueous secondary battery having high discharge potential, excellent life stability, and high safety.

[0002]

2. Description of the Related Art In recent years, with the development of devices equipped with a secondary battery, the need for a high-capacity secondary battery is rapidly increasing. Due to the necessity, lithium ion secondary batteries are being developed instead of conventional nickel cadmium batteries and nickel hydrogen batteries. Lithium ion secondary batteries have higher capacities than conventional secondary batteries, but in recent years the development of electronic devices has been remarkable, and higher capacities are desired.
In order to increase the capacity of the battery, not only the development of the electrode material but also the increase of the amount of the electrode material to be filled in the battery container is being studied. In order to increase the amount of the electrode material, attempts have been made to increase the amount of the electrode material to be applied and to reduce the porosity of the electrode material by pressing the applied electrode sheet under pressure.

FIG. 3 is a cross-sectional view of a conventional electrode sheet taken along a longitudinal direction of the electrode sheet. Usually, a coating solution containing an electrode material (hereinafter referred to as a mixture coating solution) is applied to both surfaces of the current collector 51 on the electrode sheet, and mixture layers 52 a and 52 b are formed on both surfaces of the current collector 51. Mixture layer 52 on both sides
The sum of the thicknesses of the a and 52b is larger than the thickness of the current collector 51, and the porosity of the mixture layers 52a and 52b is 10% after the press.
% To 30%.

However, when the above-mentioned electrode sheet is used, a failure such as cutting of the electrode sheet in the pressing step is liable to occur, and there is a problem in manufacturing suitability. That is, when the electrode sheet is conveyed by the press roller in the direction of arrow 53, first, the current collector 5 on which the mixture layer is not applied
1 is pressed, and then the current collector 51 on which the mixture layers 52a and 52b are applied is pressed. The thickness to be pressed depends on the thickness of the current collector 51 only.
1 and the thickness of the mixture layers 52a and 52b.
Since this change in thickness is steep, the thickness change portion 54
Current collector 51 is easily cut.

[0005] In addition, due to the above-mentioned change in thickness, when assembling the battery, when the electrode sheet and the separator are stacked and wound, the winding start portion (the current collector 51 on which the mixture layer is not applied) is formed. Portion) is difficult to form a uniform arc, and it is difficult to obtain a uniform winding group.

[0006]

The first object of the present invention is to
An object of the present invention is to provide an electrode sheet having process suitability with less trouble such as cutting in an electrode manufacturing process.

A second object of the present invention is to provide an electrode sheet capable of increasing the roundness of a winding group of electrodes.

A third object of the present invention is to provide a high-capacity secondary battery using the above-mentioned electrode sheet.

[0009]

According to one aspect of the present invention, there is provided an electrode sheet in which an electrode mixture is applied to both surfaces of a current collector, wherein the electrode sheet is provided on the current collector. Is provided, and the electrode mixture application end on the front and back surfaces has a deviation of 0.3 mm or more and 30 mm or less in the longitudinal direction of the electrode sheet.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention are as follows, but these are merely examples and need not be limited thereto.

The electrode sheet can be applied to various batteries. Hereinafter, as an example, a non-aqueous secondary battery using lithium as an active material will be described in detail.

FIGS. 1A to 1D show a method for manufacturing an electrode sheet according to an embodiment of the present invention. The electrode sheet is
It is a general term for the positive electrode sheet and the negative electrode sheet. The following manufacturing method can be applied to both the positive electrode sheet and the negative electrode sheet.

In FIG. 1A, an electrode current collector 21 is
The horizontal direction in the figure is the longitudinal direction, the depth direction in the figure is the width, and the vertical direction in the figure is the thickness. The electrode current collector 21 has a function of collecting electric charges and also serves as a support for the electrodes. The shape of the electrode current collector 21 is, for example, a rectangular thin sheet. The thickness is preferably about 5 μm or more and 30 μm or less.

The electrode current collector 21 uses aluminum, stainless steel, nickel, titanium, or an alloy thereof for the positive electrode and copper, stainless steel, nickel, titanium, or an alloy thereof for the negative electrode. The form is foil, expanded metal, punched metal, wire mesh. In particular, the electrode current collector 21 is preferably an aluminum foil for the positive electrode and a copper foil for the negative electrode.

A tape 2 is provided on the upper surface (front surface) of the electrode current collector 21.
2a, and a tape 22b on the lower surface (back surface). The thickness of each of the tapes 22a and 22b is 10 to 10
0 μm, preferably 20 to 80 μm, particularly preferably 30 to 50 μm. One end of the upper surface tape 22a and one end of the lower surface tape 22b have a length L1 in the longitudinal direction.
It is only shifted. Either of the tapes 22a and 22b may be longer (projected). Length L1 is 0.3 mm or more,
It is preferably 30 mm or less.

As shown in FIG. 1B, the electrode current collector 21
The electrode mixture 23a is applied so as to cover the upper surface of the tape 22a, and the electrode mixture 23b is applied so as to cover the lower surfaces of the electrode current collector 21 and the tape 22b. Electrode mixture 23a, 2
3b is applied after being adjusted to a predetermined thickness after the subsequent drying step and pressing step. Electrode mixture 23
The components a and 23b will be described later. After the application, the electrode sheet is dried and dehydrated. When dried, the electrode mixture 23
a and 23b generate voids therein and expand in volume. FIG.
(B) shows the state after drying.

After drying, the upper tape 22a and the lower tape 2
2b is separated from the electrode current collector 21. Top tape 22a
Is peeled off together with the electrode mixture layer on the upper surface thereof, and the lower surface tape 22b is peeled off together with the electrode mixture layer on the lower surface thereof. FIG.
As shown in (C), the electrode mixture layer 24a is left on the upper surface of the electrode current collector 21, and the electrode mixture layer 24b is left on the lower surface of the electrode current collector 21. One end of the upper electrode mixture layer 24a and one end of the lower electrode mixture layer 24b are shifted by a length L1 in the longitudinal direction.

After peeling off the tape, the electrode sheet is
6, and the electrode sheet is pressed in the thickness direction by a press roller. First, the electrode mixture layers 24a and 24b
Is pressed, the portion 32 to which only the electrode mixture layer 24b is applied is pressed, and then the portion 33 to which both the electrode mixture layers 24a and 24b are applied. Is pressed. Since the thickness of the electrode sheet is gradually increased in the above three stages, the impact force due to the change in thickness can be reduced. By reducing the impact force, it is possible to reduce an accident that the electrode sheet is cut during pressing.

As shown in FIG. 1D, the thickness of the subsequent electrode mixture layers 25a and 25b is reduced by the above pressing.
Thereafter, the electrode current collector 21 is cut at a predetermined location 28. The dimensions of the final electrode sheet are as follows. The thickness of the electrode current collector 21 is preferably 5 μm or more and 30 μm or less. It is preferable that each of the electrode mixture layers 25a and 25b is not less than the thickness of the electrode current collector 21. More preferably, each of the electrode mixture layers 25a and 25b has a thickness of 30 μm.
m or more and 400 μm or less. Electrode mixture layers 25a and 2
5b is not less than 0.3 mm and 30 mm in the longitudinal direction.
mm or less is preferable. In particular, the deviation L1 is 0.5 mm or more,
It is preferably 10 mm or less.

By having the above-mentioned deviation L1 of not less than 0.3 mm and not more than 30 mm, the problem of cutting the electrode by pressing and the problem of non-uniform winding can be improved. The optimal values for improving these two problems are different.
The optimum value of the displacement L1 for avoiding the cutting of the electrode by pressing is 0.3 mm or more and 2 mm or less, and the more preferable value of the displacement L1 for improving the winding non-uniformity is 2 mm or more and 10 mm. And the optimal value is 3 mm or more and 7 mm or less.

As described above, by adjusting the position where the tapes 22a and 22b are stuck on the electrode current collector 21, the displacement L1 can be controlled with high accuracy. FIG.
(A) to (D) show only one end of the electrode sheet, but next show the entire electrode sheet. The right end as well as the left end of the electrode sheet can be formed by the above method.
For example, Japanese Patent Application No. 9-42655 discloses a method for manufacturing an electrode sheet.
The method shown in FIG. 5 of the issue can be applied.

FIGS. 4A to 4C are views showing the entire electrode sheet, showing the relationship between the electrode current collector and the electrode mixture layers applied to both surfaces thereof.

As shown in FIG. 4A, the electrode current collector 41
The electrode mixture layer 42a is applied to the upper surface of the substrate, and the electrode mixture layer 42b is applied to the lower surface. The upper electrode mixture layer 42a has a left end LT shifted to the right (toward the center of the electrode sheet) and a right end RT shifted to the right (toward the right end of the electrode sheet) as compared to the lower electrode mixture layer 42b. I have. Both ends in the longitudinal direction of the electrode sheet are translationally symmetric in cross-sectional shape. The electrode mixture layers 42a and 42b have substantially the same length.

As shown in FIG. 4B, an electrode mixture layer 43a is applied to the upper surface of the electrode current collector 41, and an electrode mixture layer 43b is applied to the lower surface. The electrode mixture layer 43a on the upper surface
The left end LT is shifted to the right (toward the center of the electrode sheet) and the right end RT is shifted to the left (toward the center of the electrode sheet) as compared to the lower electrode mixture layer 43b. Both ends in the longitudinal direction of the electrode sheet have mirror-symmetrical cross-sectional shapes.

Further, as shown in FIG. 4C, an electrode mixture layer 44a is applied to the upper surface of the electrode current collector 41, and an electrode mixture layer 44b is applied to the lower surface. Upper electrode mixture layer 44a
The left end LT is shifted rightward (toward the center of the electrode sheet) and the right end RT is aligned with the longitudinal direction of the electrode sheet as compared with the electrode mixture layer 44b on the lower surface. In the electrode mixture layers 44a and 44b, only the left end LT is displaced in the longitudinal direction of the electrode sheet, and the right end RT is not displaced or has a deviation of less than 0.3 mm.

As shown in FIGS. 4A to 4C, various deviations can be formed. In particular, the electrode mixture layer 42a
Since the lengths of the electrode mixture layers 42a and 42b are substantially the same and the manufacturing process is simplified, the electrode mixture layers 42a and 42b shown in FIG.
Is preferable.

The displacement L1 of the electrode mixture layer in the electrode sheet
Can be adjusted by attaching a tape as described above, but is not limited to this. By controlling the starting position of applying the electrode mixture layer on the upper and lower surfaces of the electrode current collector without attaching a tape to the electrode current collector,
The shift L1 may be adjusted. Further, one surface may be taped to determine the position of the application end, and the other surface may control the start position of application. Further, the position of the application end may be controlled by mechanically scraping the uniformly applied electrode mixture layer to adjust the displacement L1.

The uncoated portion 2 of the electrode sheet shown in FIG.
A lead plate (not shown) is attached to 9. By the above method, a positive electrode sheet and a negative electrode sheet are prepared. The positive electrode sheet and the negative electrode sheet are wound by a winding machine with a separator interposed therebetween. Since the electrode sheet is gradually thickened in three stages as described above, it is easy to wind the electrode sheet, and a wound group of electrodes having high roundness can be formed. For example, a method shown in FIG. 1 of Japanese Patent Application No. 9-42655 can be applied as a method of forming the winding group.

FIG. 2 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 terminal, and the gasket 13
And is fitted to the upper opening of the battery can 11. The positive electrode sheet 8 is electrically connected to the battery lid 12. At this time, the safety valve 14 can be used as a sealing plate. In addition, a positive temperature coefficient (PTC) element 16
It is preferable to use

The electrode mixtures 23a and 23b shown in FIG.
Is a positive electrode mixture in the positive electrode sheet and a negative electrode mixture in the negative electrode sheet. 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 cathode active material can insert and release light metals.
But preferably lithium-containing transition metal acid
And more preferably Li_xCoO_Two , Li_xN
iO _Two , Li_xCo_aNi_1-aO_Two , Li_xCo_bV
_1-bO_z, Li_xCo_bFe_{1- b}O_z, Li_xMn_Two O
_Four , Li_xMnO_Two , Li_xMn_Two O_Three , Li_xMn_b
Co_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 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 negative electrode material 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),
Organic polymer fired products (polyacrylonitrile resin or fiber, furan resin, cresol resin, phenol resin), mesophase pitch fired materials, metal oxides, metal chalcogenides, lithium-containing transition metal oxides, and chalcogenides.

In particular, Ge, Sn, Pb, Bi, Al, G
Oxides and chalcogenides composed of a, Si, and Sb alone or in combination thereof are preferred. In addition, 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

The negative electrode material can be used by inserting a light metal, particularly lithium. 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 up to approximating the deposition potential of lithium.
0-700 mol% is preferable. Particularly, 100 to 600 mol% is preferable.

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-tub)
ber), EPDM (ethylene-propyl)
ene-diene methylene linka
ge), sulfonated EPDM, fluororubber, polybutadiene, and polyethylene oxide, with polyacrylic acid, carboxymethylcellulose, polytetrafluoroethylene, and polyvinylidene fluoride being particularly preferred. These are more preferably used as an aqueous dispersion latex having a particle size of 1 micron or less.

Separator 10 usable for battery (FIG. 2)
Has a high ion permeability, a certain mechanical strength,
Any material may be used as long as it is an insulating thin film. As the material, olefin polymer, fluorine polymer, cellulose polymer,
Polyimide, nylon, glass fiber, alumina (Al ₂
O ₃ ) fiber is used, and as a form, a nonwoven fabric, a woven fabric, or a microporous film is 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. In particular, the pore size is 0.
A microporous film having a thickness of from 1 to 1 μm and a thickness of from 5 to 50 μm is preferred.

The electrolyte 15 (FIG. 2) that can be used for the battery is as follows:
Propylene carbonate, ethylene car
Bonate, butylene carbonate, dimethyl carbonate
G, diethyl carbonate, 1,2-dimethoxyethane
, Γ-butyrolactone, tetrahydrofuran, 2-meth
Tyltetrahydrofuran, dimethylsulfoxide, geo
Xolan, 1,3-dioxolan, formamide, dime
Tilformamide, nitromethane, acetonitrile, ants
Methyl phosphate, methyl acetate, methyl propionate, triphosphate
Esters, trimethoxymethane, dioxolane derivatives,
Sulfolane, 3-methyl-2-oxazolidinone, pro
Pyrene carbonate derivative, tetrahydro derivative, die
At least one of butyl ether and 1,3-propane sultone
A mixture of at least one kind, and LiCl as an electrolyte.
O_Four , LiBF_Four , LiPF₆ , LiCF_Three SO_Three , L
iCF_Three CO_Two , LiAsF₆ , LiSbF₆ , LiB
_TenCl_Ten, Lithium lower aliphatic carboxylate, LiAlC
l_Four , LiCl, LiBr, LiI, chloroborane litch
Dissolves one or more salts of lithium and lithium tetraphenylborate
Are preferred. Especially propylene carbonate
Or ethylene carbonate and 1,2-dimethoxyethane
And / or mixed solvent with diethyl carbonate
iCF_Three SO_Three , LiClO_Four , LiBF_Four , And /
Or LiPF ₆ It is preferable to dissolve
At least ethylene carbonate and LiPF₆ Including
Is preferred.

The bottomed battery outer can 11 (FIG. 2) that can be used for the battery is made of a nickel-plated iron steel plate,
Stainless steel plate (SUS304, SUS304L, SU
S304N, SUS316, SUS316L, SUS4
30, SUS444, etc.), a nickel-plated stainless steel plate (same as above), aluminum or its alloy, nickel, titanium, and copper.
They are oval, square, and rectangular. 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.

Gasket 13 usable for battery (FIG. 2)
Are olefin-based polymers, fluorine-based polymers, cellulosic polymers, polyimides, and polyamides, and are preferably olefin-based polymers, particularly preferably propylene-based polymers, in view of organic solvent resistance and low moisture permeability. Further, it is preferably a block copolymer of propylene and ethylene.

[0045] 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.

As necessary, a plurality of batteries are assembled in series and / or in parallel and stored in a 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.

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

First, a positive electrode sheet was prepared. FIG. 1 (A)
As shown in FIG. 7, tapes 22a and 22b were stuck on both surfaces of a 20 μm thick positive electrode current collector 21 made of aluminum foil by shifting the length L1 = 5 mm. Tapes 22a and 2
The thickness of both 2b was 40 μm. To form the positive electrode mixture, LiCoO ₂ (87 parts by weight) was used as an active material. As the conductive agent, flaky graphite (6 parts by weight) and acetylene black (3 parts by weight) were used, and as a binder, aqueous polytetrafluoroethylene dispersion (3 parts by weight) and sodium polyacrylate (1 part by weight) were used. In addition to the active material, kneading was performed using water as a medium to obtain a slurry. The obtained slurry (positive electrode mixture 23a and 23b) was applied to both surfaces of the positive electrode current collector 21 by an extrusion method. Positive electrode current collector 21
Positive electrode mixture layers 23a and 23b each having a thickness of 130 μm were formed on both surfaces of. After drying the applied material, the tapes 22a and 22b were peeled off. Then, it is compression-molded and cut by a calender press, and the width is 56 mm and the length is 400
A strip-shaped positive electrode having a thickness of 250 mm and a thickness of 250 mm was obtained. The trouble that the positive electrode was cut by the above press did not occur.

Next, a negative electrode sheet was prepared. The length L1 = on both surfaces of the 18 μm thick negative electrode current collector 21 made of copper foil
The tapes 22a and 22b were stuck by being shifted by 0.5 mm. To form a negative electrode material, tin monoxide (73.3 parts by weight), silicon dioxide (19.5 parts by weight), magnesium oxide (3.5 parts by weight), and boron oxide (3.7 parts by weight) were dry-processed. Mix for 10 hours (1200 ° C) under argon atmosphere
After calcination, it is cooled and pulverized, and S having an average particle size of 4.5 μm is obtained.
nSi _0.6 Mg _0.2 B _0.2 O _2.7 was obtained as a negative electrode material.

To form a negative electrode mixture, flake graphite (6 parts by weight) as a conductive agent and an aqueous dispersion of polyvinylidene fluoride (4 parts by weight) as a conductive agent were added to the negative electrode material (88 parts by weight). And carboxymethylcellulose (1 part by weight) and lithium acetate (1 part by weight) were added and kneaded using water as a medium to obtain a slurry. The obtained slurry (negative electrode mixture 23a and 23b) is applied to both surfaces of the negative electrode current collector 21 by an extrusion method, and dried, tape-peeled, compression-molded and cut in the same manner as the positive electrode to obtain a width of 58 mm. A belt-shaped negative electrode having a thickness of 440 mm and a thickness of 78 μm was obtained. As in the case of the positive electrode, no trouble of cutting the negative electrode by pressing occurred.

Before cutting, the sample was placed in a low humidity atmosphere (dew point: -5
(0 ° C.), the positive electrode and the negative electrode obtained above were dehydrated and dried.
The dehydration drying is performed using a far-infrared heater at a temperature of 200 to
Performed at 250 ° C. for 2 hours. Thereafter, a lead plate made of nickel was ultrasonically welded to an uncoated portion of the negative electrode sheet (copper current collector). Further, a lead plate was ultrasonically welded to an exposed portion of a positive electrode sheet (aluminum current collector) having a thickness of 20 μm. An adhesive tape using a silicone adhesive as a base material was adhered to the welded portion of the lead to protect the lead. As shown in FIG. 2, the obtained positive electrode sheet 8 with a lead, a microporous polyethylene film separator 10, and a negative electrode sheet 9 were wound by a winding machine. This winding could be performed smoothly and easily, and a winding group of electrodes having high roundness was obtained.

The wound body was housed in a nickel-plated iron bottomed cylindrical battery can 11 also serving as a negative electrode terminal. The electrolyte 15 contains 0.9 and 0.1 mol of LiPF ₆ and LiBF ₄ , respectively, per liter, and the solvent has a volume ratio of ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl propionate of 2: 4: 3: 1. Consisting of a mixture of This electrolyte 15 is supplied to the battery can 11
Was injected. The battery lid 12 having the positive electrode terminal was caulked via the gasket 13 to produce a cylindrical battery. The positive electrode terminal 12 was connected to the positive electrode sheet 8 and the battery can 11 was connected to the negative electrode sheet 9 by a lead terminal in advance. Safety valve 14
Was attached to the battery can 11 via the gasket 13. A battery was manufactured by the above method.

This electrode sheet did not cause any manufacturing troubles such as an abnormal shape during roller pressing or winding. A plurality of batteries were manufactured by changing the displacement L1 of the electrode mixture on the current collector. When the displacement L1 of the positive electrode was 0.1 mm, a part of the plurality of positive electrodes was cut at the time of pressing, and a part of the shape was not uniform at the time of winding and a trouble that the battery can could not be inserted occurred. When the displacement L1 was shifted by more than 30 mm, the above trouble did not occur.
Battery capacity has dropped significantly. The displacement L1 is preferably 0.3 mm or more and 30 mm or less.

As described above, by disposing the electrode mixture layers on both surfaces of the electrode current collector by shifting each other by the length L1,
The inconvenience of cutting the electrode sheet at the time of manufacturing the electrode sheet (particularly at the time of press working) can be reduced. In addition, since the electrode sheet can be wound with high roundness and housed in a battery can, battery production and performance efficiency can be improved.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example,
It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0057]

According to the present invention, an electrode sheet having high productivity can be obtained by shifting the electrode mixture application ends on both sides by 0.3 mm or more and 30 mm or less as in the present invention.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method for manufacturing an electrode sheet according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a cylindrical battery used in Examples.

FIG. 3 is a cross-sectional view showing a conventional electrode sheet.

FIG. 4 is a sectional view of an electrode sheet.

[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, 51 electrode current collector 22 tape 23, 52 electrode mixture

Claims (16)

[Claims] An electrode sheet comprising an electrode mixture coated on both sides of a current collector, wherein the electrode sheet has an uncoated portion of the electrode mixture on the current collector, and an electrode on the front and back surfaces. An electrode sheet in which the mixture application end has a deviation of 0.3 mm or more and 30 mm or less in the longitudinal direction of the electrode sheet. 2. The electrode sheet according to claim 1, wherein both application ends of the electrode mixture in the longitudinal direction of the electrode sheet have symmetrical cross-sectional shapes on both sides of the electrode sheet. 3. The current collector has a thickness of 5 μm or more and 30 μm or more.
The electrode sheet according to claim 1, which is not more than m. 4. The electrode sheet according to claim 1, wherein a dry film thickness of the electrode mixture applied to the front and back surfaces of the electrode sheet is larger than a thickness of the current collector. 5. The electrode sheet according to claim 1, wherein the electrode mixture application end on the front and back surfaces has a deviation of 0.5 mm or more and 10 mm or less in a longitudinal direction. 6. One end of the electrode mixture on the front and back surfaces in the longitudinal direction has a deviation of 0.3 mm or more and 30 mm or less, and each of the other ends also has a deviation of 0.3 mm or more and 30 mm or less. Item 5. The electrode sheet according to items 1 to 4. 7. One end of the electrode mixture on the front and back surfaces in the longitudinal direction has a deviation of 0.3 mm or more and 30 mm or less, and the deviation of each other end is 0 mm or more and less than 0.3 mm. An electrode sheet according to any one of claims 1 to 4. 8. The electrode sheet according to claim 1, wherein said current collector is made of aluminum or copper. 9. A dry film thickness of the electrode mixture applied to the front and back surfaces of the electrode sheet is 30 μm or more, respectively.
4. The electrode sheet according to claim 3, wherein the thickness is not more than μm. 10. The electrode sheet according to claim 5, wherein the electrode mixture application end on the front and back surfaces has a deviation of 0.3 mm or more and 2 mm or less in the longitudinal direction. 11. The electrode sheet according to claim 5, wherein the electrode mixture application end on the front and back surfaces has a deviation of 2 mm or more and 10 mm or less in a longitudinal direction. 12. A battery having a positive electrode sheet and a negative electrode sheet each having an electrode mixture coated on both surfaces of a current collector, wherein each of the positive electrode sheet and the negative electrode sheet has an uncoated portion of the electrode mixture. , And the electrode mixture application ends on the front and back sides are respectively 0.3 mm or more and 30 m
m or less. 13. A step of applying and drying an electrode mixture on both sides of a current collector to form an electrode mixture layer in which one end of the application on both sides is shifted from each other by 0.3 mm or more and 30 mm or less. (B) press-pressing the electrode mixture layer formed on the current collector to form an electrode sheet. 14. The step (a) includes: (a-1) a step of forming a tape on a current collector; and (a-2) an electrode mixture layer on the current collector so as to cover the tape. The step of forming the electrode sheet according to claim 13, wherein the step (b) includes the step of: (b-1) removing the tape together with the electrode mixture layer thereon from the current collector. Method. 15. A step of (a) applying and drying an electrode mixture on both sides of a current collector to form an electrode mixture layer in which one end of the application on both sides is shifted by 0.3 mm or more and 30 mm or less from each other; (B) a step of press-pressing the electrode mixture layer formed on the current collector to form an electrode sheet; and (c) a step of winding the electrode sheet to form an electrode group. Production method. 16. A step of (a) applying and drying an electrode mixture on both sides of a current collector to form an electrode mixture layer in which one end of the application on both sides is shifted by 0.3 mm or more and 30 mm or less from each other; (B) a step of pressing the electrode mixture layer formed on the current collector to form an electrode sheet; (c) a step of winding the electrode sheet to form an electrode group; and (d) an electrode. And housing the group in a battery can.