JP6212951B2 - Method for producing battery electrode member - Google Patents

Description

The present invention relates to a method of manufacturing a battery electrode member which is applied to a lithium ion secondary battery. More specifically, the positive electrode paint or the negative electrode paint is discharged from the slit of the die head onto the surface of the substrate held and transported by the coating roll, and the coating film is formed on almost the entire surface, or intermittently by opening and closing the valve. by discharging, coated portions and the cell electrode member which is intermittently applied to form a Minuriko unit, method for producing a battery electrode member in which at least two paint is coated on the same surface It is about.

  The electrode member of a lithium ion secondary battery is, for example, a secondary battery (including a capacitor) used in an electric vehicle, a fuel cell vehicle, a hybrid electric vehicle, a household power storage facility, an electric tool, a train, a small portable device, etc. Used for electrode parts. In particular, the development of lithium ion secondary batteries has been remarkable in recent years. As for the required performance of batteries for the automobile field, high capacity, high output, cycle stability, cost, occupied volume, safety, etc. are regarded as important.

The components that make up a lithium ion secondary battery can be broadly divided into positive and negative electrodes, separators, and electrolytes, among which electrodes are made of materials such as current collectors, active materials, binders, and conductive materials. Has been.
In recent years, intensive research has been conducted on in-vehicle lithium ion secondary batteries, but research and development are progressing not only in terms of materials such as active materials but also in terms of electrode shapes and processing processes.

In particular, during electrode preparation, a slurry obtained by diluting a material containing an active material with a solvent as described above is often applied onto a current collector that is an electrode base material. However, depending on the coating accuracy and drying conditions, the performance may be increased. It will greatly affect.
In addition, the dried film after slurry application is mostly pressed to improve film density, improve adhesion, smooth the coating surface, and reduce internal resistance.
Regarding coating accuracy, it is very important to obtain a smooth coated surface with a desired thickness and the coating position and shape. Only then can stable battery performance be maintained.

By obtaining a smooth coated surface to be an electrode on the current collector and then stacking or winding it, a large-capacity battery can be obtained, and the battery performance equivalent to the theoretical value of the material is expressed without loss. You can make it.
In addition, regarding the position and shape, if the application position of the electrode coating film serving as the positive electrode and the negative electrode is different, or if the application shape is not as designed, the battery capacity is affected, or a part that is not used for the battery reaction may be generated. Furthermore, precipitation is partially generated, and the influence is great from the viewpoint of performance, cost, and safety, such as a short circuit caused by breaking through the separator and coming into contact with the counter electrode.

  In intermittent coating, which is often used for laminated batteries, and continuous coating, which is used for wound batteries, there are many cases where pressing is performed in either case. Due to the difference in elongation between the material (for example, aluminum foil, copper foil, resin base material, etc.) and the electrode coating film, the adhesion may not be well removed or cracks may occur on handling.

  In addition, as one of the battery performance improvement, there is a case where the thickness of the electrode coating film is increased in order to increase the discharge capacity, but when the thickness of the electrode coating film is increased, cracks are more likely to occur, and the surface of the electrode coating film The electron moving distance is increased by the distance from the electrode substrate (metal foil or the like), that is, the thickness of the electrode coating film. That is, resistance becomes longer due to the longer electron movement distance, and the efficiency is lowered, leading to a decrease in battery performance.

  Further, most of the electrode coating film is a positive electrode or negative electrode active material, and in addition, a conductive assistant and a binder in an amount as required are mixed. In the active material, electrons are exchanged from ions to the electrode base material via the conductive auxiliary agent. However, the active material itself has very low conductivity, so the conductive auxiliary agent is just around the corner. Otherwise, the efficiency will be poor, and the electrons generated from the reaction and generation on the coating film surface side away from the electrode substrate, that is, the interface side in contact with the electrolyte, will reach the electrode substrate in the normal direction of the electrode substrate. Means that the resistance is large, and the loss as battery performance is also large.

If the proportion of the conductive auxiliary agent is increased, the amount of the active material is inevitably reduced, and if the amount of the active material is reduced, the reaction field where electrons are exchanged may be reduced, resulting in a decrease in battery capacity. Even if the proportion of the conductive auxiliary agent is slightly increased, the conductive auxiliary agent is not efficiently arranged, so that a large improvement in battery performance cannot be expected.
In order to solve such problems, several patents have been filed.
For example, in patent document 1, it is trying to improve adhesiveness with an electrode base material by providing a base layer. Patent Document 2 proposes a secondary electrode electrode having excellent charge / discharge cycle characteristics by using a columnar electrode made of a silicon-based active material or the like.

  Furthermore, by applying a method of providing a coated part and an uncoated part on the same surface, called stripe coating, a current collecting function is provided to the uncoated part, resulting in a large current output with low internal resistance. A lithium secondary battery having excellent characteristics (see, for example, Patent Document 3) or two electrode active material layers are applied sequentially or simultaneously so as to have a function as an electrode to improve output characteristics. (See, for example, Patent Document 4), and a method for improving the adhesion between the electrode coating film and the current collector by partially providing a layer with a gradient in binder concentration (for example, Patent Document) 5)) has been proposed.

JP 2012-156109 A JP 2003-303586 A Japanese Patent No. 3511517 Japanese Patent No. 5070680 JP 2013-12393 A

In the above-mentioned Patent Document 1, by providing the base layer, the adhesion with the electrode substrate is improved, the exchange of electrons becomes smooth, the resistance is reduced, and the battery performance is also improved. However, no consideration has been given to electrons generated far from the electrode substrate such as the surface of the coating film, and loss reduction has not been achieved.
In addition, when a columnar electrode as shown in Patent Document 2 is used, the number of steps increases in order to produce a columnar shape. In addition, when the electrode base material is crafted in a separate process, the interface between the columnar part and the coating film part is distorted, and the electrons cannot be transferred well, so there are many cases where the resistance becomes conversely.

Further, in any of the methods described in Patent Document 3 and Patent Document 4, the battery performance is not significantly improved, and in Patent Document 5, the adhesion between the electrode coating film and the current collector is improved, but the binder rich This layer has internal resistance, and although it is effective under specific battery evaluation conditions, the overall performance has been reduced.
It is an object of the present invention, while suppressing the occurrence of Hibiya cracks, and its object is to provide a manufacturing method of the possible battery electrode member of improving the excellent battery performance in adhesion.

One aspect of the present invention is a method for producing an electrode member for a battery, in which a positive or negative electrode paint is discharged from a slit of a die head to form an electrode coating film on the surface of an electrode substrate held and conveyed by a coating roll. At least two kinds of paints including a paint containing a positive electrode or a negative electrode active material by a die head and a paint having a conductive band having a volume resistivity lower than that of an active material band formed by applying the paint. The active material bands that are simultaneously discharged to the region excluding both ends in the width direction of the electrode material, and the active material bands and the conductive bands are alternately arranged adjacent to each other in the width direction of the electrode base material, and are alternately arranged. And by forming the slit of the die head so that the active material band is located on both sides in the width direction of the conductive band and performing the discharge, uncoated portions are formed at both ends in the width direction of the electrode substrate. Do Unishi a method for manufacturing a battery electrode member characterized by forming the active material band immediately inside is.
The coating width of the electrode coating film is W (mm), the coating width per one of the active material bands is L (mm), the number of the active material bands is a (book), the per one of the conductive bands When the coating width is L ′ (mm) and the number of conductive bands is b (lines) and these satisfy the condition of W = L × a + L ′ × b, the coating width L of the active material band and the conductive band The coating width L ′ may satisfy both 0.02 mm <L ′ <W / 2 and L ′ × b <W / 2.
The electrode coating film may be formed by continuous coating or intermittent coating.

According to one aspect of the present invention, in a battery electrode member in which a positive electrode paint or a negative electrode paint is ejected from a slit of a die head to form an electrode coating surface on the surface of a substrate that is carried by a coating roll, the same surface is provided. A coating film in which at least two types of coating materials are discharged is formed adjacent to the horizontal direction, and one or more types of coating films (active material bands) having better conductivity than a coating film containing an active material (active material zone) Because it is a conductive band), the electrons that have reacted and become electrons on the coating surface side away from the electrode substrate do not necessarily move in the normal direction of the coating film or electrode substrate, It can also be attracted to the side of the resistive conductive band, that is, in a direction nearly parallel to the coating film or electrode substrate. Therefore, the resistance in the electrode can be reduced and current loss can be reduced.
Further, by forming at least two kinds of coating films at the same time, the boundary between the different materials can be mixed and the adhesion between the coating films can be improved.

It is an example of the block diagram showing the whole coating equipment applied to this invention. It is sectional drawing which shows an example of the coating head applied to this invention. It is sectional drawing which shows an example of the coating head applied to this invention. It is sectional drawing which shows an example of the coating head applied to this invention. It is sectional drawing which shows an example of the coating head applied to this invention. It is a block diagram which shows an example of the electrode surface of the electrode member for batteries in this invention. (A) is a block diagram which shows an example of the shim board by the side of the conductive band in this invention, (b) It is a block diagram which shows an example of the shim board by the side of an active material band.

Embodiments of the present invention will be described below.
In addition, it is not limited only to the form described below.
(Coating equipment)
First, the coating apparatus used when producing the battery electrode member in this invention is demonstrated.

FIG. 1 is a schematic configuration diagram illustrating an example of a coating apparatus 100, which includes a liquid supply tank 1, a liquid feed pump 2, a switching valve 3, a coating head 4, a strainer 5, a coating roll 6, and an electrode base material 7. The liquid supply tank 1, the liquid feed pump 2, the switching valve 3 and the coating head 4 are connected via a pipe.
The coating liquid in the liquid supply tank 1 is supplied to the coating head 4 via the liquid feed pump 2 and the strainer 5. A switching valve 3 is inserted between the liquid feed pump 2 and the strainer 5, and by operating the switching valve 3, the supply destination of the coating liquid discharged from the liquid feed pump 2 is changed between the strainer 5 side and the liquid feed. Switch between tank 1 side.

  The liquid supply tank 1 only needs to have a sufficient capacity with respect to the amount of coating liquid to be fed, and the capacity is not particularly defined. In addition, a stirring blade can be provided to prevent sedimentation of inorganic components in the coating material in the liquid supply tank 1 and to ensure a dispersed state. Further, the inside of the liquid supply tank 1 may be depressurized or pressurized as necessary to assist defoaming and liquid feeding. Further, in order to reduce the resistance between the inner wall surface of the liquid supply tank 1 and the paint and improve the fluidity, the inner wall surface of the liquid supply tank 1 may be subjected to fluorine processing or mirror surface processing. Moreover, you may serve as the liquid supply tank 1 and the liquid feeding pump 2 with one apparatus.

As the liquid feed pump 2, a Mono pump, a diaphragm pump, a sine pump, a bellows pump, a tube diaphragm pump, a plunger pump, a syringe pump, or the like can be applied. Any one of these pumps may be appropriately selected in accordance with characteristics such as paint viscosity and discharge amount, pulsation, and sliding foreign matter.
The discharge amount of the liquid feed pump 2 is determined by the amount to be applied within a certain period of time, that is, the application width, the application thickness, and the application speed. In order to satisfy the determined discharge amount per rotation and uniformly coat the coating film As long as the number of rotations required for the pump is within the specification of the number of rotations per hour, it can be applied and is not limited. However, it is preferable to select a pump having an appropriate discharge amount that can be operated within the specifications as much as possible.

  As the switching valve 3, a piston valve, a diaphragm valve, a sampling valve, a ball valve, a butterfly valve, a check valve, a syringe valve, or the like can be applied. Any switchable valve that can block the flow path in one direction and change the flow path in the other direction can be applied. If possible, it is preferable to select a valve that does not affect the pressure in the liquid feeding pipe or the coating head 4 by opening and closing the valve.

  The coating head 4 is a slot die type die head. The cutting edge shape, cutting edge angle, manifold shape, manifold capacity, specularity of the head inner surface, supply port diameter, and supply position of the coating head 4 are not particularly limited. 2, 3, 4, and 5, the paint is applied to the blade edge by holding at least two manifolds and adjusting the shim shape and the setting position, that is, the arrangement position of each member. The paints are merged or applied after being applied. That is, as shown in FIG. 6, the coated film is formed with a coating film of a predetermined width made of one paint and a coating film of a predetermined width made of the other paint adjacent to each other in the horizontal direction. It has come to be.

FIG. 6 shows an example of the configuration of the electrode surface, 32 is an active material band application portion made of one paint, and 33 is a conductive band application portion made of the other paint. The part 32 and the conductive band application part 33 serve as an electrode coating film.
By applying the coating material on the electrode surface, as shown in FIG. 6, the active material band application part 32 and the conductive band application part 33 are alternately formed in stripes in the horizontal direction. In addition, 31 in FIG. 6 is an uncoated part.

  As shown in FIG. 2, FIG. 3, FIG. 4, and FIG. 5, the coating head 4 may have an upstream head and a downstream head for each of the different types of paints. Hold upstream and downstream die heads, use a plate that divides the top and bottom in the middle, and set application shims on the top and bottom, and determine the shape of each paint discharge port with the shims in contact with the top and bottom manifolds. May be. Of course, the plate set in the middle is required not to be deformed even by the pressure during liquid feeding application.

  2, 3, 4, and 5, 11 is a die head and manifold on the active material band application side, 12 is a liquid supply port on the active material band application side, and 13 is a shim plate on the active material band application side. , 14 is a partition steel plate, 15 is a downstream die head on the active material band application side, 16 is a sandwich die head, 17 is a die head and manifold on the conductive band application side, 18 is a shim plate on the conductive band application side, and 19 is a conductive band application side. The downstream die head 20 is a liquid supply port on the conductive band application side.

FIGS. 7A and 7B show examples of the shapes of the shim plate 13 on the active material band application side and the shim plate 18 on the conductive band application side.
The shim plate 13 on the active material band application side has a shape having a striped shim (34 in FIG. 7A) having a width of Lmm. The shim plate 18 on the conductive band application side has a shape having b striped shims (36 in FIG. 7B) having a width L ′ mm.

  The coating width of the electrode coating film is W (mm), the coating width per coating film (that is, the width of the shim opening of the shim plate 13) is L (mm), and the active material. The number of bands is a (book), the coating width per coating film (that is, the width of the shim opening of the shim plate 18) is L '(mm), and the number of conductive bands is b (book). ), That is, when W = L × a + L ′ × b, the coating width L of the active material band and the coating width L ′ of the conductive band are 0.02 mm <L ′ <W / 2 and L ′ × b < Set to satisfy both W / 2.

  The tip of the shim may be right-angled, or may be cut out or set so that the liquid spreads somewhat, or to prevent horns due to neck-in. In FIG. 7A, reference numeral 35 denotes the opening (width Lmm) of the shim 34 on the active material band application side. In FIG. 7B, 37 represents the opening (width L′ mm) of the shim 36 on the conductive band application side.

  However, accuracy is required for the striped shim. An opening of about 10 μm can be obtained in the case of laser processing, and about 1 μm in the case of wet etching, etc., but if the opening is narrow, the pressure in the pipe and the die will rise too much, and the coating material to be applied The viscosity must be considerably reduced. Furthermore, basically, the strainer 5 is passed in the middle of the pipe to dissolve the particles in the paint, but there are some that have a large particle size of the powder in the paint and a few tens of μm, so the opening is not wider than that. Particles are clogged and can no longer be applied.

If the area of the conductive band is larger than that of the active material band, the reaction field that can be generated in the active material band is small in the first place, and the battery performance is reduced. Therefore, in the present invention, the opening width is limited as described above.
The method for supplying the coating material to the coating head 4 may be appropriately selected depending on the application width. Basically, when reducing pressure unevenness in the width direction, that is, application unevenness, it is preferable to supply from the center portion, but appropriately selected. is necessary.

  Moreover, in the coating head 4, the position of the blade edge which discharges two types of paints being the same indicates that the gaps at the time of applying the paints are substantially the same. Therefore, it is necessary to make the paint solids substantially the same size, and to make the wet film thickness, that is, the setting gap of the cutting edge for discharging two kinds of paints of the coating head 4 substantially the same. The coating can be applied even if the solid content of the paint and the wet film thickness are somewhat different, and there is no problem if the film thicknesses of the two kinds of paints after drying are equivalent. If possible, it is preferable that the two types of paint do not have horn-like bulges at both ends caused by neck-in.

The active material zone mainly includes a positive electrode or negative electrode active material, and includes a conductive additive, a binder, a solvent, and, if necessary, an additive.
Lithium-containing transition metal oxide is used as an active material for the positive electrode, and lithium ions and electrons are exchanged on the surface of the active material or inside the electrolyte so that an electric current is generated.
The positive electrode active material is a compound that can occlude and release lithium ions, and the inorganic compound includes a composition formula, Li _x MO ₂ or Li _y M ₂ O ₄ (where M is a transition metal, 0 ≦ x ≦ 1, 1 ≦ y ≦ 2).

A composite oxide, an oxide having pores on a tunnel, a layered metal chalcogenide, or a lithium ion-containing chalcogen compound can be used.
As a specific _{example, LiCoO 2, NiO 2, Ni} 2 O 3, Mn 2 O4, LMn 2 O 4, MnO 2, Fe 2 O 3, Fe 3 O 4, FeO 2, V 2 O 5, V 6 O 13 Group VI metal compounds such as VO _x , Nb ₂ O ₅ , Bi ₂ O ₃ , Sb ₂ O _3, etc., and Group VI metal compounds such as CrO ₃ , Cr ₂ O ₃ , MoO ₃ , MoS ₂ , WO ₃ , SeO ₂ TiO ₂ , TiS ₂ , SiO ₂ , SnO, CuO, CuO ₂ , Ag ₂ O, CuS, CuSO _{4 and the} like.

Further, a mixture of two or more of the above transition metals, or a compound containing two or more transition metals, so-called binary system or ternary system may be used.
Furthermore, examples of the organic material include conductive polymer compounds such as polypyrrole, polyaniline, polyparaphenylene, polyacetylene, and polyacene materials.
The electrode layer composition of the positive electrode and the production method itself are not particularly limited, but it is preferable to finally apply a paint mixed with necessary materials to the electrode substrate 7 and dry it to form an electrode.

  Examples of the negative electrode active material include materials containing natural graphite, artificial graphite, amorphous carbon, carbon black, amorphous carbon, and the like, and when a slight amount of different elements are present in these, Among these alloys, tin, silicon and the like, those capable of absorbing and releasing lithium ions can be mentioned.

As the conductive assistant, a conductive agent is contained in order to conduct electrons generated in the active material to the current collector without loss. A carbon-based material is often used as the conductive agent, and it is preferable to select an appropriate amount depending on how familiar the active material and the binder are with how efficiently electrons are conducted in a small amount. Specific examples include carbon black, ketjen black, acetylene black, carbon whisker, carbon fiber, natural graphite, artificial graphite, carbon nanoparticles and nanotubes, titanium oxide, ruthenium oxide, aluminum, nickel and other metal powders and fibers. These may be used alone or in combination of two or more. If necessary, a dispersion medium may be added.
Examples of the dispersion medium include polar solvents such as N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylsulfamide, and water.

  An example of the binder is a fluorine-based resin. For example, polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene chloride (CTFE) copolymer, vinylidene fluoride-hexafluoropropylene fluororubber, vinylidene fluoride- Fluoropolymers such as tetrafluoroethylene-hexafluoropropylene fluorine rubber, vinylidene fluoride-tetrafluoroethylene-perfluoroalkyl vinyl ether fluorine rubber, polypropylene oxide, polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene / butadiene rubber, propylene / Examples include butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, and various latexes. Can. In addition, polyacryl, polyolefin, polyamide, polyimide, polyamideimide, epoxy resin, bakelite, etc. may be used alone or in combination.

  In addition, alumina particles, silica particles, latex particles and other non-ionic conductive particles that have a particle diameter equal to or smaller than the electrode layer thickness are not disturbed, and stable non-electron conductive fine particles in the ionic conductive material can be used for film thickness control and processability. It may be filled for the purpose of improving the mechanical strength of the film or stabilizing the shape. For the same reason, a porous non-electron conductive polymer matrix material (such as various nonwoven fabrics) may be filled. Of course, it is better if the above-mentioned reason can be captured by an electron conductive substance.

  As the additive, it is preferable not to be added in consideration of the influence on the battery performance. However, if the leveling property of the coating material, the wettability to the electrode substrate 7 is improved, the compatibility between the coating materials, the viscosity adjustment, the rheological property improvement, etc. When used, it is preferable to minimize the source as much as possible and, if possible, volatilize together when the solvent is dried.

  In addition, the conductive band comprises a coating film having a lower volume resistivity than the active material band and good conductivity. The conductive coating film component of the conductive band mainly includes a conductive additive, a binder, a solvent, and an additive as necessary. It is made up of. As the conductive auxiliary agent, the same as the electrode coating film may be used. However, it is preferable that the binder and the additive are dispersed as little as possible. If the dispersion is good, there is no need to use it. Since it is applied simultaneously with the active material zone, there is a balance between viscosity and the like, but if possible, the ratio of conductive assistant: binder ratio = 50/50 to 99/1 (weight ratio) is preferable. If possible, it is more preferable that the conductive auxiliary agent ratio is 95/5 or more. In addition, the same binder and solvent as the electrode coating film can be used. Rather, it is preferable to use the same material because the wettability and leveling property at the time of application are approximate.

  The coating roll 6 is required to be a perfect circle and no distortion. This is because the gap between the cutting edge of the coating head 4 and the coating roll 6 often needs to be set in units of several μm. The surface is chrome-plated and surface-polished so that the electrode base material 7 can be transported without being damaged even if there is a slight difference between the transport speed of the electrode base material 7 and the roll peripheral speed. Of course, it must be installed without any difference between left and right.

  Regarding the electrode base material 7, as the battery base material, metal foil is generally used in many cases, copper foil and aluminum foil are often used, and a single metal or alloy, or a plurality of metals are laminated or pasted. It can also be combined. However, it is not limited to metal foils, but plastic substrates that are conductive or kneaded with conductive materials, or those that have surface conductivity by coating the surface, metal It may be a material bonded with plastic. If it is used as an electrode with a substrate having no uneven thickness, it can be appropriately selected.

Although the strainer 5 shown in FIG. 1 is not necessarily required, it has the effect of releasing the particles in the paint aggregated in the liquid feeding, reduces streaks in the coated film, prevents the coating surface from being aggregated, By stabilizing the liquid and coating pressure, the coating accuracy is improved and, as a result, the battery performance is also improved.
The shape of the strainer 5 may be appropriately selected from shapes such as punching metal and wire edges. Further, the roughness of the eyes and the pressure resistance may be selected in consideration of the paint to be fed, the amount of liquid to be fed, the liquid feeding pressure, and the like.

When the electrode coating film is applied using the coating equipment having the above-described configuration, as shown in FIG. 6, the coating film as the active material band and the coating film as the conductive band are striped. The electrode coating film formed alternately adjacent in the horizontal direction is formed. That is, a conductive band having a small volume resistivity and good conductivity is formed in a stripe shape in appearance.
Here, since the coating film as the conductive band is a coating film having better conductivity than the coating film as the electric band active material band, it reacts on the surface side of the coating film away from the electrode substrate 7 and reacts with electrons. The formed material does not necessarily move in the normal direction of the coating film or the electrode substrate 7 but can be attracted to the low-resistance conductive band side, that is, in a direction almost parallel to the coating film or the electrode substrate 7. Therefore, the resistance in the battery electrode member can be lowered, that is, the current loss can be reduced.

Further, as described above, by forming at least two kinds of coating films at the same time, the boundary is mixed with respect to the adhesion between different materials, and the adhesion between the coating films can be improved.
Furthermore, since the conductive band does not contain an active material, it can be mixed with a larger amount of binder than the active material band, and there are more conductive assistants, so an electrode coating with good conductivity and good adhesion can be realized. This is also advantageous in terms of battery life.

In addition, since electrons can be moved with low resistance, charging / discharging with a large current value and charging / discharging over a long period of time are possible, and battery performance can be improved as a whole.
In addition, even if it is a case where an electrode coating film is produced by any of continuous coating and intermittent coating, it can apply.

Moreover, although the case where the electrode coating film is formed with two types of paints has been described, the present invention is not limited to this, and the electrode coating film can be formed with three or more types of paints. In this case, an electrode coating film may be formed with one type of paint that becomes an active material band and two or more types of paint that becomes a conductive band. In the case where there are a plurality of paints that become conductive bands, the total coating width of the plurality of paint films that become conductive bands is the aforementioned L ′ (mm), and the total number of the plurality of paint films that become conductive bands is the aforementioned b (book) may be set so as to satisfy the above condition.
Further, the active material band and the conductive band are not limited to the case of providing a plurality, and the electrode coating film may be formed by arranging one conductive band and arranging the active material band on both sides thereof.

Examples will be described below.
However, the examples do not limit the present invention.

Example 1
<Paint preparation and substrate>
The following positive electrode paints were prepared as positive electrode paints for the active material zone.
Active material: LiMn2O4 (manufactured by Mitsui Kinzoku Co., Ltd.): 90 parts by mass, conductive material: acetylene black (manufactured by Denki Kagaku Kogyo): 5 parts by mass, binder: PVDF (manufactured by Kureha): 5 parts by mass, NMP as a solvent (Mitsubishi) Chemical) was mixed to prepare a paint having a viscosity of about 10,000 mPa · s. The conductive good paint as the conductive band paint was as follows.
Conductive material: Acetylene black (manufactured by Denki Kagaku Kogyo): 97 parts by mass, binder: PVDF (manufactured by Kureha): 3 parts by mass, dispersant: manufactured by BYK: 0.1 part by mass of NMP (manufactured by Mitsubishi Chemical) as a solvent By mixing, a paint having a viscosity of about 6000 mPa · s was obtained.

  As the electrode substrate 7, an aluminum foil having a thickness of 15 μm (1085 material, manufactured by Tokai Aluminum Co., Ltd.) was used. The following materials were prepared as the negative electrode paint for the counter electrode. Active material: Natural graphite (manufactured by Hitachi Chemical): 90 parts by mass Conductive agent: Acetylene black (manufactured by Denki Kagaku Kogyo): 4 parts by mass, Binder: SBR (manufactured by Nippon Zeon): 4 parts by mass (solid content conversion) thickener : CMC (Carboxymethylcellulose): 2 parts, Furthermore, water was used as a diluent solvent, and a coating material was prepared so as to have a solid content of 50%. The base material used was electrolytic copper foil (Furukawa Electric).

<Apparatus and manufacturing method>
Of the three types of coating materials prepared above, an active material zone and a charging zone are provided on the positive electrode side, and only one type of coating material is applied on the negative electrode side and used only as a counter electrode.

  On the positive electrode side, continuous coating was carried out by a slot die method so that the average film thickness (at the time of drying) of the coated part of both the active material zone and the charging zone was 100 μm. The thickness of the shim plate on the active material band application side was 1.5 mm, and the thickness of the shim plate on the conductive band application side was 1.0 mm. At that time, as shown in FIG. 1, a liquid feed pump 2 (Mono pump: manufactured by Hyojin Equipment Co., Ltd.) is stored in a liquid supply tank 1 coated with an inner surface Teflon (registered trademark) and equipped with a stirring blade. ) Were connected by a liquid feeding pipe having a nominal diameter of 1S, and connected from the switching valve 3 (manufactured by Koganei Co., Ltd.) to the coating head 4. Moreover, in the area | region of the unapplied part, it piped so that an unapplied part may be formed by making it return to the liquid supply tank 1 from the switching valve 3. FIG. At this time, the setting of the coating head 4 is formed as shown in FIG. 3, and the positions of the shim plate 13 on the active material band side and the shim plate 18 on the charging band side of the blade edge portion are applied to the electrode substrate 7. It was set to be applied to the electrode base material 7 in a state where the two kinds of paints were in contact with each other just before being applied.

Under the conditions, the active material application part width total: application width W: about 300 mm, active material band L: 30 mm, conductive band L ′: 1 mm width with respect to the application width 400 mm of the electrode substrate 7 Thirty coatings were applied alternately, and coating and drying were performed at a coating speed of 2 m / min to obtain a battery electrode member.
For the negative electrode, the above material was applied by a slot die method, and a thickness corresponding to a capacity corresponding to 1.2 times the positive electrode capacity was continuously applied with a coating width of 300 mm to prepare a battery electrode member.

(Example 2)
A coating similar to that in Example 1 was prepared and applied.
However, at that time, with respect to the coating width of the electrode base material 7: 300 mm, the active material band coating portion width L: 15 mm and the conductive band coating width: 15 mm are coated alternately so that the coating speed is 15 mm. Continuous coating was performed at a speed of 2 m / min to obtain a battery electrode.

(Comparative Example 1)
A coating similar to that in Example 1 was prepared and applied.
However, at that time, with respect to the coating width W: 300 mm, the active material band coating width L: 30 mm and the conductive band coating width L ′: 6 mm, 30 are coated alternately, and the coating speed is 2 m / min. A continuous electrode was applied at a speed to obtain a battery electrode.

(Comparative Example 2)
The same coating material as in Example 1 was prepared, and continuous coating was performed. However, at that time, there was no coating portion with good conductivity, and only the active material coating portion was obtained to obtain a lithium ion battery electrode film.

(Evaluation items and evaluation methods)
The coating films obtained in Examples and Comparative Examples were set in a press machine, pressed, and pressed so that the active material band portion had a desired density (2.6 g / cm ³ ). Obtained.

(1) Battery performance 1:
A coin cell was produced using each of the obtained electrode sheets. The electrolyte contained 1 mol of LiPF ₆ and mixed at a ratio of ethylene carbonate / dimethyl carbonate (1/1 vol), and the separator used was PP (manufactured by Celgard).
When the coin cell was charged and discharged for 3 cycles in the order of 0.1 C, 0.2 C, 0.5 C, 1 C, 2 C, 5 C, and 10 C in a 25 ° C. environment, each discharge capacity at 0.5 C and 5 C was The discharge capacity storage ratio A was calculated from the average value.
A = Discharge capacity at 5C / Discharge capacity at 0.5C

(2) Battery performance 2:
Discharge in each example when the discharge capacity (mAh / g) of Example 1 is set to 100% in the discharge capacity (per electrode film weight) at 5 C when measuring charge / discharge performance 1 (that is, battery performance 1) The volume ratio was calculated.

(3) Adhesion:
The obtained sheet was once wound around a 1-inch paper tube in the coating flow direction, unwound, and then covered with cello tape (registered trademark) (manufactured by Nichiban: 25 mm width) so as to include an active material band and a conductive band. ) Was peeled off and peeled in the direction of 180 degrees, and the adhesion of the coating film was evaluated.
Evaluation: ○: No peeling △: Partial peeling ×: Full peeling (result)
The measurement results are shown in Table 1 below.

  From the results of Table 1, it was confirmed that the battery performance was improved and the adhesion to the electrode substrate was improved according to the present invention.

1: Liquid supply tank 2: Liquid feed pump 3: Switching valve 4: Coating head 5: Strainer 6: Coating roll 7: Electrode substrate 11: Active material band application side die head and manifold 12: Active material band application side liquid supply Mouth 13: Active material band application side shim plate 14: Partition steel plate 15: Active material band application side downstream die head 16: Pinch die head 17: Conductive band application side die head and manifold 18: Conductive band application side shim plate 19: Conductive band application side Downstream die head 20: conductive band application side liquid supply port 11: active material band application side die head and manifold 31: unapplied part (ear part)
32: Active material band application part 33: Conductive band application part 34: Active material band application shim 35: Active material application shim opening 36: Conductive band application shim 37: Conductive band application shim opening

Claims (3)

In the method for producing an electrode member for a battery in which a positive electrode or negative electrode paint is discharged from a slit of a die head to form an electrode coating film on the electrode substrate surface held and conveyed by the coating roll,
By the die head, at least two kinds of paints including a paint containing a positive electrode or a negative electrode active material and a paint having a conductive band having a volume resistivity lower than that of an active material band formed by applying the paint are applied to the electrode base. The active material that is simultaneously discharged to a region excluding both ends in the width direction of the material, and the active material bands and the conductive bands are alternately arranged adjacent to each other in the width direction of the electrode base material, and are alternately arranged. By disposing the slit of the die head so that the active material band is located on both sides in the width direction of the band and the conductive band and performing the discharge, uncoated portions are formed at both ends in the width direction of the electrode substrate. A method for producing a battery electrode member, characterized in that the active material zone is formed immediately inside .   The coating width of the electrode coating film is W (mm), the coating width per one of the active material bands is L (mm), the number of the active material bands is a (book), the per one of the conductive bands When the coating width is L ′ (mm), the number of the conductive bands is b (lines), and these satisfy the condition of W = L × a + L ′ × b,
  The application width L of the active material band and the application width L ′ of the conductive band are:
  The battery electrode member manufacturing method according to claim 1, wherein both 0.02 mm <L ′ <W / 2 and L ′ × b <W / 2 are satisfied.   The method for producing a battery electrode member according to claim 1 or 2, wherein the electrode coating film is formed by continuous coating or intermittent coating.

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