WO2018179205A1

WO2018179205A1 - Battery electrode, method for manufacturing same, and device for manufacturing electrode

Info

Publication number: WO2018179205A1
Application number: PCT/JP2017/013219
Authority: WO
Inventors: 乙幡　牧宏
Original assignee: 日本電気株式会社
Priority date: 2017-03-30
Filing date: 2017-03-30
Publication date: 2018-10-04
Also published as: JPWO2018179205A1; JP6908103B2

Abstract

The purpose of the present invention is to provide: a battery electrode in which a coating layer can be formed in a boundary section with a sufficient margin; and a method for manufacturing same. To this end, this method for manufacturing an electrode is a method in which a second layer is coated on at least a boundary section between a first layer and a base material having a portion on which the first layer is formed. The method is characterized in that, in a region directly in front of the boundary section on the base material, with respect to the gap between a coating device and the base material, the second layer is coated with a second gap that is smaller than a first gap corresponding to a wet thickness that is determined by the amount of discharged coating fluid and by the moving speed of the base material, and coating is performed on the first layer with a third gap corresponding to the sum of the thickness of the first layer and the first gap.

Description

Battery electrode, manufacturing method thereof, and electrode manufacturing apparatus

The present invention relates to a battery electrode, a manufacturing method thereof, and an electrode manufacturing apparatus.

Secondary batteries are widely used as power sources for portable devices such as mobile phones, digital cameras, and notebook PCs, and as power sources for vehicles and homes. Among them, a lithium ion secondary battery having a high energy density and a light weight is an energy storage device indispensable for life.

Secondary batteries are roughly classified into wound type and stacked type. A battery element of a wound secondary battery has a structure in which a long positive electrode and a negative electrode are wound a plurality of times in a state of being overlapped while being separated by a separator. The stacked type has a structure in which positive electrodes and negative electrodes are alternately stacked via separators.

Secondary batteries tend to increase in capacity year after year. Therefore, if a short circuit occurs, the secondary battery may generate more heat, so it is important to improve the safety of the secondary battery. As a method for improving the safety of the secondary battery, for example, a technique is known in which an insulating layer is formed in a range extending over both the surface of the active material layer and the exposed surface of the current collector (Patent Document 1). .

In Patent Document 1, an insulating member is formed so as to cover a boundary portion between a coated portion (portion where the positive electrode active material layer is formed) and an uncoated portion (portion where the positive electrode active material layer is not formed). As shown in FIG. 2 of the same document, one end portion of the insulating member is located on the thin portion of the positive electrode active material layer, and the other end portion is located on the uncoated portion ((0030). ) Paragraph). The insulating member is applied by a die coater (paragraph (0037)).

Japanese Unexamined Patent Publication No. 2017-010644

When coating insulating members with a die coater, the gap between the current collector foil and the tip of the coating die is set to a thickness approximately equal to the wet thickness of the slurry in the uncoated portion, and the active material thickness in the coated portion. + Wet thickness is set. Thereby, a uniform insulating layer can be applied.

However, it is difficult to control the gap by following the change in the film thickness at the boundary of the intermittently applied portion of the active material layer. Therefore, in order to prevent contact between the tip of the die and the active material layer, an insulating member is applied with a gap wider than the sum of the thickness of the applied portion and the wet thickness at the boundary between the coated portion and the uncoated portion of the active material layer (with a margin). Need to be provided). In the coating by the die coater, the distance (gap) between the die tip and the substrate is usually set to be approximately equal to the wet thickness determined by the coating liquid discharge amount and the line speed. However, when it is desired to provide a margin at the boundary portion, if the gap is set larger than the wet thickness, a portion that is not coated at the boundary portion is generated as shown in FIGS. is there.

The present invention has been made in view of the problems as described above, and the purpose thereof is to form an insulating layer on the surface of the active material layer before and after the boundary of the intermittent coating portion with a die coater. It is to provide a battery electrode that can be coated with a margin so that the tip of the die coater and the active material layer do not come in contact with each other and a manufacturing method thereof.

The present invention is a method for producing an electrode, wherein a second layer is applied to at least a boundary portion between the base material and the first layer with respect to a base material partially formed with a first layer,
In the region before the boundary portion on the substrate, a gap between the coating device and the substrate is a first thickness corresponding to a wet thickness determined by a coating liquid discharge amount of the coating device and a moving speed of the substrate. The second layer is coated with a second gap smaller than the gap, and the third layer is coated on the first layer by adding the thickness of the first layer to the first gap. It is the manufacturing method of the electrode which makes it.

Further, the present invention is a method for producing an electrode, wherein a second layer is applied to at least a boundary portion between the first layer and the substrate with respect to the substrate on which the first layer is formed in part.
On the first layer, the thickness of the first layer is added to the first gap corresponding to the wet thickness determined by the coating liquid discharge amount and the moving speed of the base material. The second gap is applied with a third gap, and a fourth gap which is smaller than the third gap and larger than the thickness of the first layer in the region before the boundary on the first layer. The method for producing an electrode according to claim 1, wherein the second layer is applied and the second layer is applied with the first gap on the substrate.

Further, the present invention provides a base material, a first layer formed on at least a part of the base material, a boundary between the first layer and the base material on at least the first layer and the base material. A battery electrode comprising: a second layer formed across the boundary portion, on the first layer, and on the base material and having a thickness that decreases in this order.

Further, the present invention is formed across the boundary between the substrate, the first layer formed on at least a part of the substrate, at least the substrate on the first layer, on the boundary, A battery electrode comprising: a second layer having a thickness that decreases in this order in a region adjacent to the boundary portion on the first layer on the base material.

The present invention also includes a transport mechanism for transporting the base material partially formed of the first layer;
A coating die for applying a material to the substrate;
A control circuit for controlling the position of the coating die;
With
The control circuit includes:
In the region before the boundary portion on the substrate, a gap between the coating device and the substrate is a first thickness corresponding to a wet thickness determined by a coating liquid discharge amount of the coating device and a moving speed of the substrate. The second layer is applied with a second gap smaller than the gap, and on the first layer, the third gap is applied by adding the thickness of the first layer to the first gap, or
Or
On the first layer, the gap between the coating device and the first layer is applied, the second layer is applied with the third gap, and the region on the first layer before the boundary portion is the third layer. The second layer is applied with a fourth gap that is smaller than the gap and larger than the thickness of the first layer, and the second layer is applied with the first gap on the substrate.
An electrode manufacturing apparatus that controls a position of the coating die.

According to the present invention, when forming an insulating layer on the surface of the active material layer before and after the boundary of the intermittently coated portion in the die coater, the margin is provided so that the tip of the die coater and the active material layer do not contact without interrupting the insulating layer. It is possible to provide a battery electrode that can be applied with a coating and a method for producing the same.

It is typical sectional drawing which shows the electrode formation process of the 1st Embodiment of this invention. It is typical sectional drawing which shows the electrode formation process of the 2nd Embodiment of this invention. It is a schematic diagram explaining the 3rd Embodiment of this invention, and is a figure which shows the example which manufactures the electrode for batteries continuously by intermittent coating. It is a typical top view which shows the process in which the electrode for batteries is manufactured from the electrode applied intermittently. It is a schematic diagram explaining the 4th Embodiment of this invention, and is a figure which shows another example which manufactures the electrode for batteries continuously by intermittent coating. It is a schematic diagram explaining the method for controlling a gap. It is typical sectional drawing which shows the manufacturing method of the electrode of the Example of this invention. It is typical sectional drawing which shows the structure of a battery. It is typical sectional drawing which took out and showed only one electrode from the battery 1 of FIG.8 (b). In the Example of this invention, the experimental result at the time of coating from the low side to the high side across the level | step difference of the boundary part 15 is shown. FIG. 6 is a schematic cross-sectional view showing that when a gap is set larger than the wet thickness in order to provide a margin at the boundary, a portion that is not coated is generated at the boundary.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
The battery electrode manufacturing method according to the first embodiment of the present invention will be described. FIGS. 1A and 1B are schematic cross-sectional views showing a process of forming a second layer 12 with a coating apparatus 14 on a base material 10 on which a first layer 11 is partially formed. In the present embodiment, coating is performed from the lower side (base material 10 side) to the higher side (first layer 11 side) across the boundary portion 15.

As shown in FIG. 1, a first layer 11 is formed on a part of the substrate 10. The second layer 12 is applied by discharging the coating liquid from the coating device 14 so as to straddle at least the step of the boundary portion 15 on the substrate 10 and the first layer 11. In the present embodiment, the substrate 10 is moved to the right in the drawing at a constant speed without moving the coating apparatus 14. A right-pointing arrow in FIG. 1 indicates a direction in which the substrate 10 is moved. The one in which the first layer is formed on the base material or the one in which the first layer and the second layer are formed on the base material is referred to herein as a battery electrode. It may be simply abbreviated as an electrode. In order to form the second layer 12, a gap 16 is set between the coating device 14 and the substrate 10. Note that the gap is a distance between the tip portion discharged from the coating liquid of the coating apparatus and the substrate. The coating thickness (hereinafter referred to as wet thickness) of the second layer 12 is determined from the coating liquid discharge amount per predetermined time of the coating device 14 and the moving speed of the substrate 10. The size of the gap 16 at a location away from the boundary 15 is set to be the same as the wet thickness. This gap 16 is defined as a first gap.

When approaching the boundary 15 (point A in FIG. 1A), the gap is intentionally changed to a gap 16 'smaller than the gap 16. Then, a part of the discharged coating liquid is not applied as the second layer, but is stored as a liquid reservoir 13 at the front end portion of the front surface of the coating apparatus. This gap 16 'is defined as a second gap. When an appropriate distance is taken in front of the boundary portion 15 (appropriate “running distance” is set), a sufficient amount of liquid pool can be collected, and the accumulated liquid pool gathers at the boundary portion 15 and The second layer is sufficiently thicker than before and after. The thick coating 18 serves as a margin for preventing the first layer 11 or the substrate 10 from being exposed.

After that, increase the gap at the point just before the step at the boundary. Since there is a control delay or the like, if the gap starts to increase after approaching the boundary too much, the tip of the coating apparatus hits the first layer 11 and damages the first layer. Therefore, it starts to enlarge the gap just before the appropriate distance. The gap 16 ″ is a total value of the thickness of the first layer 11 and the thickness of the gap 16 (first gap). This gap is the third gap.

In addition, it is also possible to apply with the thickness of the gap 16 ′ without applying the thickness of the gap 16 from the beginning of the application of the first layer 11. If the base material 10 is sufficiently smooth and has few irregularities, the base material 10 is not exposed even if the first layer on the base material 10 is thinned. Further, the second layer 12 may be applied to the entire surface of the base material 10 and the first layer 11, or may be applied only before and after the boundary portion 15 at a minimum.
(Second Embodiment)
The first embodiment is a case where the coating is performed from the lower side (base material side) to the higher side (first layer side) across the boundary portion 15. However, conversely, it is also possible to form a thick coating on the boundary portion by coating from the high side to the low side across the step of the boundary portion 25.

FIGS. 2A and 2B are schematic cross-sectional views for explaining the second embodiment. The coating liquid is discharged from the coating device 24 so as to straddle the boundary portion 25 between the base material 20 and the first layer 21, thereby coating the second layer 22. Also in this embodiment, the base material 20 is moved to the right side of the drawing at a constant speed without moving the coating device 24. A right-pointing arrow in FIG. 2 indicates a direction in which the substrate 20 is moved. In order to form the second layer 22, a gap 26 (third gap) is set between the coating device 24 and the substrate 20. The wet thickness (first gap) of the second layer 22 is determined from the coating liquid discharge amount per predetermined time of the coating device 24 and the moving speed of the substrate 20. The size of the gap 26 in the region away from the boundary portion 25 on the second layer 22 is set to a size (third gap) obtained by adding the thickness of the first layer 21 to the wet thickness. Therefore, on the second layer 22 in a region away from the boundary portion 25, the second layer is applied with the same thickness as the first gap.

When approaching the boundary portion 25 (point B in FIG. 2A), the gap is intentionally changed to a gap 26 '(fourth gap) smaller than the third gap. The difference between the third gap and the fourth gap may be approximately the same as the difference between the first gap and the second gap in the first embodiment. Further, the distance between the boundary portion 25 and the point B may be the same as the distance between the boundary portion 15 and the point A in FIG. Then, a part of the discharged coating liquid is not applied as the second layer, but is stored as a liquid reservoir 23 at the front end portion of the front surface of the coating apparatus. When an appropriate distance is taken from the boundary portion 25 in front, a sufficient amount of liquid can be stored, and a second layer sufficiently thicker than before and after the boundary portion 25 can be applied. This thick coating 28 serves as a margin for preventing the first layer 21 or the substrate 20 from being exposed.

After that, when the tip of the coating device 24 passes the step of the boundary portion 25, the gap is reduced to the first gap to form the gap 26 ″.

The second layer 22 may be applied to the entire surface of the base material 20 and the first layer 21, or may be applied only before and after the boundary 25.
(Third embodiment)
FIG. 3 is a schematic diagram for explaining a third embodiment of the present invention, and is a diagram showing an example of continuously producing battery electrodes by intermittent coating. The die coater 300 includes at least one backup roller 301 on which the current collector foil 30 is bridged, and a coating die 34 disposed so as to face the surface of the current collector foil 30. The die coater 300 also includes a drive mechanism (not shown) that moves the coating die 34 forward and backward (having an actuator, a link mechanism, etc.), a mechanism that discharges material from the nozzle 34a of the coating die 34, and their operations. And a control circuit 302 for controlling. The coating die 34 is configured to move forward and backward with respect to the backup roller 301. At the time of coating, the insulating layer 32 rotates in the direction indicated by the arrow in FIG. 3 and is coated at a predetermined thickness at a predetermined position from the bottom to the top.

In FIG. 3, a material obtained by intermittently coating the active material layer 31 on one surface of the current collector foil 30 at a predetermined interval is stretched over the backup roller 301.

Further, the die coater 300 is provided with a detector 39. The detector 39 detects the position of the end portion of the active material layer 31 formed on the conveyed current collector foil using a difference in light reflectance from the current collector foil 30 or the like. The detector 39 is, for example, an imaging device such as a CCD (Charge Coupled Device) camera, a reflectance measuring device using laser light, or the like. The detector 39 is electrically connected to the control circuit 302. The control circuit 302 controls the gap between the coating die 34 and the current collector foil 30 or the active material layer 31 from the positions of both ends of the active material layer 31 detected by the detector 39 and the rotational speed of the backup roller 301. Calculate timing. Based on the calculation result, as described in the first and second embodiments, a thick coating 38 of the insulating layer 32 is formed at the boundary.

Note that the control circuit 302 may be configured to control the rotation operation of the backup roller 301 and / or other drive rollers (not shown). The control circuit 302 may include a microcomputer having a CPU (Central Processing Unit), a memory, and the like, and the operation of the control circuit 302 may be controlled by a computer program.

The current collector foil 30 is a long member drawn from a roll (not shown). The control circuit 302 controls the position of the coating die 34 and the discharge at an appropriate timing in accordance with the rotation of the backup roller 301, thereby collecting the current material in which the active material layer 31 is intermittently formed. An insulating layer 32 is intermittently applied on the foil 30. In FIG. 3, the insulating layer 32 is intermittently applied to the top and side surfaces of the active material layer 31, and a region where the insulating layer 32 is not applied is provided on the current collector foil 30 between the adjacent active material layers 31. However, it may be applied to the entire surface.

FIG. 4 is a schematic plan view showing a process of manufacturing the battery electrode from the intermittently coated electrode. As shown in FIG. 4A, the current collector foil 30 is cut along a cutting line 40a parallel to the length direction thereof (this process is also referred to as “slit”) to form a plurality of long members. Then, as shown in FIG. 4B, the electrode is further punched into the shape of the electrode cutting line 40b, whereby a final electrode as shown in FIG. 4C is obtained. Note that the negative electrode can be manufactured in the same manner as the positive electrode.

In FIG. 3, the active material layer 31 and the insulating layer 32 are formed only on one surface of the current collector foil 30, but the active material layer and the insulating layer may be formed on both surfaces of the current collector foil 30. In FIG. 3, the end portion of the insulating layer 32 is described as an ideal shape, but may be tapered as shown in FIGS. It is desirable that the end portion of the active material layer 31 is covered without being interrupted so long as it does not become higher than the height of the insulating layer 32 on the active material layer 31 (active material layer thickness + insulating layer thickness).
(Fourth embodiment)
FIG. 5 is a schematic diagram for explaining a fourth embodiment of the present invention, and is a diagram showing another example of continuously producing battery electrodes by intermittent coating. The die coater 400 is different from the die coater 300 in that it includes two coating dies (coating dies 54 and 55) and

film thickness meters

56, 56 ′, and 56 ″. The first film thickness meter 56 is disposed upstream of the first backup roller 401, and the second film thickness meter 56 ′ is disposed between the first backup roller 401 and the second backup roller 402, The third film thickness meter 56 ″ is disposed downstream of the second backup roller 402. In FIG. 5, the control circuit and the edge detector of the active material layer are omitted.

First, the active material layer 41 is intermittently applied at a predetermined interval on one surface of the current collector foil 40 by the coating die 54. After the active material layer 41 is applied, the insulating layer 52 is applied with a coating die 55. 401 and 402 are backup rollers. The

film thickness meters

56, 56 ', and 56 "measure the film thicknesses of the current collector foil 40, the active material layer 41, and the insulating layer 52, respectively.

As the film thickness meter, a known film thickness meter such as a radiation (β-ray, γ-ray, X-ray) film thickness meter or a laser film thickness meter can be used. According to such a configuration, the thickness of the current collector foil 40, the active material layer 51, and the insulating layer 52 on the active material layer can be derived. In addition, it is good also as a structure which provides only one or only two among three film thickness meters. Further, a camera for detecting coating defects may be provided at any one or both of the positions of the film thickness meters 56 ′ and 56 ″. In FIG. 5, the insulating layer 52 is intermittently applied to the top and side surfaces of the active material layer 41, and a region where the insulating layer 52 is not applied is provided on the current collector foil 40 between the adjacent active material layers 41. However, it may be applied to the entire surface. In FIG. 5, the end portion of the insulating layer 52 is described as an ideal shape, but may be tapered as shown in FIGS. 1 and 2. It is desirable that the end portion of the active material layer 41 is covered without being interrupted as long as it does not become higher than the height of the insulating layer 52 on the active material layer 41 (active material layer thickness + insulating layer thickness).
(Fifth embodiment)
FIG. 6 is a schematic diagram for explaining a method for controlling the gap. As a method for controlling the gap, it is possible to control the distance from the electrode by moving the coating apparatus closer or away. If the coating apparatus is a die coater, it is first conceivable that the die 60 main body approaches or leaves. In addition, as shown in a cross section in FIG. 6A, there is also a method in which the die tip portion is constituted by a piezoelectric body 61, and a voltage is applied to the piezoelectric body to expand and contract to bring the die close or close.

Also, as shown in FIG. 6B, there is a method in which a mechanism for changing the angle of the die body with respect to the electrode is provided so that the gap is tilted in the traveling direction when the gap is reduced. A rotating shaft 62 passing through the die central axis is provided on the opposite side of the die body from the electrode so that the angle can be varied with respect to the electrode. If the rotation shaft and the die body are fixed, the rotation shaft may not be in the die body.

Further, as shown in FIG. 6C, there is also a method of controlling the gap by moving the position of the backup roller 63 up and down and changing the position of the electrode mounted thereon. Note that the upper and lower sides of the die body and the methods shown in FIGS. 6A, 6B, and 6C may be appropriately combined.
(Sixth embodiment)
An example of the configuration of the secondary battery manufactured by the methods of the first to fifth embodiments will be described.

The lithium ion secondary battery 1 includes a battery element 400 and an outer container 450 that encloses the battery element 400 together with an electrolyte, as shown in FIGS. 7, 8A, and 8B. The battery element 400 in the stacked lithium ion secondary battery 1 has a structure in which the positive electrode 100 and the negative electrode 200 are alternately and repeatedly stacked while being separated by a separator 350 as shown in FIG. In this example, a separator is provided between the positive electrode and the negative electrode, but may not be provided. For example, an insulating layer can also serve as a separator by forming an insulating layer on at least one of the positive electrode and the negative electrode facing the counter electrode.

The positive electrode 100 is formed by forming an active material layer or the like on a current collector, and includes a positive electrode active material forming portion 110 and a positive electrode active material layer non-forming portion 120 in which no active material layer is formed to provide a lead portion. And have. Similarly, the negative electrode 200 also has an active material layer formed on a current collector, and has a negative electrode active material forming part 210 and a negative electrode active material non-forming part 220.

Each positive electrode active material non-formed part is bundled by ultrasonic bonding or the like to form a positive electrode lead part 410 as shown in FIG. Similarly, the negative electrode active material non-forming portions 220 are also bundled to form a negative electrode lead portion 420. The positive electrode lead portion 410 and the negative electrode lead portion 420 are electrically connected to the positive electrode terminal 430 and the negative electrode terminal 440, respectively.

The battery element 400 is enclosed in the outer container 450 so that the positive electrode terminal 430 and the negative electrode terminal 440 are drawn out of the outer container 450. The outer container 450 may be made of a known material and configuration. For example, it may be formed of a film member in which an inner surface layer 460 made of a heat sealing resin, a metal layer 470 made of an aluminum thin film, and a surface layer 480 made of a protective resin are laminated.

As for battery manufacturing procedures other than electrode manufacturing, existing methods can basically be used. That is, the positive electrode 100, the negative electrode 200, and the separator 350 prepared in advance are alternately stacked as shown in FIG. Then, as shown in FIG. 8A, the battery element 400 in which the positive electrode terminal 430 and the negative electrode terminal 440 are electrically connected is hermetically sealed together with the electrolyte in the outer container 450, and a cross section is shown in FIG. 8B. Such a lithium ion secondary battery 1 is obtained.

The insulating

layers

180 and 185 in FIG. 8B are the second layers described in the above embodiment. In this example, both surfaces of the current collector foil 155 are covered with an insulating layer. FIG. 9A is a schematic cross-sectional view showing only one electrode taken out from the lithium ion secondary battery 1 of FIG. 8B. The current collector foil 155 is bent to connect to the positive terminal 430 or the negative terminal 440. Therefore, stress is applied to the boundary portion 150 between the current collector foil 155 and the active material layer, and the current collector foil may be broken or the insulating layer may be peeled off. However, in this embodiment, since the insulating layer at the boundary is thick, it is strong against bending and high in strength. Therefore, it is possible to reduce the possibility of breakage of the current collector foil and peeling of the insulating layer. On the other hand, when the insulating layer at the boundary is not thick as shown in FIG. 9B, it is vulnerable to bending, stress is applied to the boundary 150, and the current collector foil may break or the insulating layer may peel off.

FIG. 10 is a table showing experimental results when coating is performed from the low side to the high side across the step of the boundary portion 15. In this embodiment, a die coater is used as a coating apparatus, a current collector foil of a secondary battery as a base material, an active material layer of the secondary battery as a first layer, and an insulating layer as a second layer. The discharge amount of the coating liquid from the die is always a constant amount. The insulating layer Wet thickness and the active material layer thickness are respectively a coating thickness of the insulating layer and a coating thickness of the active material layer.

Further, the gap change margin is a moving distance from a position where the gap, which has been reduced (gap 16 ′) to form the liquid reservoir 13, to a constant value (gap 16 ″) from a position where the gap starts to increase. Since it takes a little time to raise the die, the die starts to rise before reaching the boundary 15 and reaches the gap 16 ″ before the boundary 15. In this embodiment, there are two types of 0.7 and 1.5 mm. The gap is controlled by moving the die up and down, but may be controlled by measuring the distance between the roll and the die tip using a known position sensor or the like. The run-up distance is a distance obtained by shortening the gap to the gap 16 'and is a distance for forming a liquid pool. In this embodiment, there are three types of 0, 3, and 5 mm. The gap shortening rate indicates how much the gap should be reduced during the approach distance compared to the large gap area (gap 16) in front of it. In this embodiment, it is 0, 20, 50%. That is, the gap is reduced by 0%, 20%, and 50%, respectively, compared to before the gap is reduced.

In addition, No. in FIG. Reference numerals 1 and 4 are comparative examples. In these two cases, the gap change margin is zero, which means that the gap 16 is not shortened to the gap 16 ′ (gap shortening ratio = 0%) before the step of the boundary portion, and the coating is performed with the gap 16 as it is. To do.

◯ also means that the step is not exposed and is covered with a thick insulating layer. Δ means that the step is covered with an insulating layer which is not as thick as in the case of ○ but has a sufficient thickness. X means that the insulating layer was not covered with a step and there was a place where the step was exposed.

In FIG. When the gap shortening ratio of 1 is 0%, a step is exposed (determination x). On the other hand, no. As shown in 2 and 3, if the gap change margin is 1.5 mm, the run-up distance is 5 mm, and the gap shortening ratio is 20% and 50%, the coating will be judged as △ and ○, respectively. We were able to coat. The insulating layer Wet thickness and the active material layer thickness are different. Nos. 4, 5 and 6 are also No. The same can be said for

cases

1, 2 and 3.
No. 7 and 8 are cases in which the gap change margin is reduced to 0.7 mm and the running distance is shortened to 3 mm. Also in this case, the step was not exposed and was covered with a thick insulating layer.

The same applies to the case of coating from the high side to the low side across the step of the boundary 25 as in the second embodiment, and the insulating layer Wet thickness, the active material layer thickness, etc. described in FIG. 10 are the same. If so, the gap change margin, the approach distance, and the gap reduction ratio may be the same.
(Electrode constituent material)
Here, the material constituting the electrode will be described including the insulating layer. The following is an example, and the material is not particularly limited, and a known material can be used.

Examples of base materials are current collector foils and current collectors of secondary batteries, but aluminum, nickel, copper, silver, alloys thereof, and the like can be used as the positive electrode material. The material for the negative electrode is the same as the material for the positive electrode, but in particular, copper, iron, nickel, chromium-based, molybdenum-based stainless steel, aluminum, aluminum alloy, or the like can be used.

An example of the first layer is an active material layer of a secondary battery. Examples of the positive electrode active material include LiNiO ₂ , Li _y Ni _(1-x) M _x O ₂ (formula A) (where 0 ≦ x <1, 0 <y ≦ 1.2, and M is at least one element selected from the group consisting of Co, Al, Mn, Fe, Ti, and B).

Also, for example, Li _α Ni _β Co _γ Mn _δ O ₂ (0 <α ≦ 1.2, preferably 1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.7, γ ≦ 0.2), Li _α Ni _β Co _γ Al _δ O ₂ (0 <α ≦ 1.2, preferably 1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.6, preferably β ≧ 0.7, γ ≦ 0.2), etc. In particular, LiNi _β Co _γ Mn _δ O ₂ (0.75 ≦ β ≦ 0.85, 0.05 ≦ γ ≦ 0.15, 0.10 ≦ δ ≦ 0.20) may be mentioned. More specifically, for example, LiNi _0.8 Co _0.05 Mn _0.15 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O _2, _LiNi 0.8 _Co 0.1 _Al can be preferably used 0.1 _{O 2} or the like.
Note that when the Ni content is increased (for example, exceeding 0.6), the energy density of the battery can be increased, but the present invention is effective even in such a case.

In addition, two or more compounds represented by the above (formula A) may be used as a mixture, for example, NCM532 or NCM523 and NCM433 in a range of 9: 1 to 1: 9 (as a typical example) 2: 1) are also preferably used as a mixture. Furthermore, in (Formula A), a material having a high Ni content (x is 0.4 or less) and a material having a Ni content not exceeding 0.5 (x is 0.5 or more, for example, NCM433) are mixed. As a result, a battery having a high capacity and high thermal stability can be formed.

Other than the above, as the positive electrode active material, for example, LiMnO ₂ , Li _x Mn ₂ O ₄ (0 <x <2), Li ₂ MnO ₃ , Li _x Mn _1.5 Ni _0.5 O ₄ (0 <x < 2) Lithium manganate having a layered structure or spinel structure such as LiCoO ₂ or a part of these transition metals replaced with another metal; Li in these lithium transition metal oxides more than the stoichiometric composition And those having an olivine structure such as LiFePO ₄ . Furthermore, a material in which these metal oxides are partially substituted with Al, Fe, P, Ti, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, etc. Can also be used. Any of the positive electrode active materials described above can be used alone or in combination of two or more.

Also, the negative electrode active material contains metal and / or metal oxide and carbon as the negative electrode active material. Examples of the metal include Li, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, or alloys of two or more thereof. . Moreover, you may use these metals or alloys in mixture of 2 or more types. These metals or alloys may contain one or more non-metallic elements.

Examples of the metal oxide include silicon oxide, aluminum oxide, tin oxide, indium oxide, zinc oxide, lithium oxide, and composites thereof. In this embodiment, it is preferable that tin oxide or silicon oxide is included as the negative electrode active material, and it is more preferable that silicon oxide is included. This is because silicon oxide is relatively stable and hardly causes a reaction with other compounds. In addition, for example, 0.1 to 5% by mass of one or more elements selected from nitrogen, boron and sulfur can be added to the metal oxide. By carrying out like this, the electrical conductivity of a metal oxide can be improved. In addition, the electrical conductivity can be similarly improved by coating a metal or metal oxide with a conductive material such as carbon by a method such as vapor deposition.

Examples of carbon include graphite, amorphous carbon, diamond-like carbon, carbon nanotubes, and composites thereof. Here, graphite with high crystallinity has high electrical conductivity, and is excellent in adhesiveness and voltage flatness with a negative electrode current collector made of a metal such as copper. On the other hand, since amorphous carbon having low crystallinity has a relatively small volume expansion, it has a high effect of relaxing the volume expansion of the entire negative electrode, and deterioration due to non-uniformity such as crystal grain boundaries and defects hardly occurs.

Metals and metal oxides are characterized by a lithium acceptability that is much greater than that of carbon. Therefore, the energy density of the battery can be improved by using a large amount of metal and metal oxide as the negative electrode active material. In order to achieve a high energy density, it is preferable that the content ratio of the metal and / or metal oxide in the negative electrode active material is high. A larger amount of metal and / or metal oxide is preferable because the capacity of the whole negative electrode increases. The metal and / or metal oxide is preferably contained in the negative electrode in an amount of 0.1% by mass or more of the negative electrode active material, more preferably 1% by mass or more, and still more preferably 10% by mass or more. However, the metal and / or metal oxide has a large volume change when lithium is occluded / released compared to carbon, and the electrical connection may be lost. It is below mass%. As described above, the negative electrode active material is a material capable of reversibly receiving and releasing lithium ions in accordance with charge and discharge in the negative electrode, and does not include other binders.

The second layer is, for example, an insulating layer that covers the positive electrode or the negative electrode, and for example, an inorganic oxide can be used. Examples of the inorganic oxide include magnesium oxide, silicon oxide, alumina, zirconia, oxide of titanium oxide, barium titanate, calcium titanate, lead titanate, γ-LiAlO ₂ , LiTiO _{3 and the} like. An organic film can also be used as the insulating layer. For example, polypropylene, polyethylene, aramid, polyimide, polyamideimide, or the like can be used.

As mentioned above, although several forms of this invention were demonstrated referring drawings, this invention is not necessarily limited to the specific content demonstrated above, suitably in the range which does not deviate from the meaning of this invention. It can be changed.

A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.
(Appendix 1)
A method for producing an electrode, in which a second layer is applied to at least a boundary portion between the base material and the first layer with respect to the base material partially formed with a first layer,
In the region before the boundary portion on the substrate, a gap between the coating device and the substrate is a first thickness corresponding to a wet thickness determined by a coating liquid discharge amount of the coating device and a moving speed of the substrate. The second layer is coated with a second gap smaller than the gap, and the third layer is coated on the first layer by adding the thickness of the first layer to the first gap. A method for manufacturing an electrode.
(Appendix 2)
The method for producing an electrode according to appendix 1, wherein the second layer is applied on the base material before the boundary portion while forming a liquid pool of the coating liquid between the coating apparatus and the base material. .
(Appendix 3)
After applying with the second gap, immediately before the boundary portion, the gap is changed from the second gap to the third gap, and the second layer is applied. Electrode manufacturing method.
(Appendix 4)
The method for producing an electrode according to any one of appendices 1 to 3, wherein the second gap is a distance that is 20% or more smaller than the first gap on the base material 1 mm or more in front of the boundary portion. .
(Appendix 5)
The method for manufacturing an electrode according to (4), wherein the gap is reduced between 20% and 50% from the first gap at least 1 mm before the boundary portion.
(Appendix 6)
Any one of Supplementary Notes 1 to 5, wherein the second layer is applied with the first gap on the substrate, and then the second layer is applied with the second gap in a region before the boundary. The manufacturing method of the electrode as described in claim | item.
(Appendix 7)
A method of manufacturing an electrode, wherein a second layer is applied to at least a boundary portion between the first layer and the substrate with respect to a substrate on which a first layer is formed in part,
On the first layer, the thickness of the first layer is added to the first gap corresponding to the wet thickness determined by the coating liquid discharge amount and the moving speed of the base material. The second gap is applied with a third gap, and a fourth gap which is smaller than the third gap and larger than the thickness of the first layer in the region before the boundary on the first layer. The method for producing an electrode, wherein the second layer is applied and the second layer is applied on the substrate with the first gap.
(Appendix 8)
The electrode according to appendix 7, wherein the second layer is applied while forming a liquid pool of the coating liquid between the coating apparatus and the first layer on the first layer before the boundary portion. Production method.
(Appendix 9)
The method for manufacturing an electrode according to

appendix

7 or 8, wherein the fourth gap is a distance that is 20% or more smaller than the third gap on the first layer that is 1 mm or more before the boundary.
(Appendix 10)
The fourth gap according to any one of appendices 7 to 9, wherein the fourth gap is set to a distance that is 20% or more and 50% or less smaller than the third gap on the first layer that is 1 mm or more before the boundary portion. Electrode manufacturing method.
(Appendix 11)
Any one of appendixes 7 to 10, wherein the second layer is applied with the third gap on the first layer, and then the second layer is applied with the fourth gap in the region before the boundary. The method for producing an electrode according to one item.
(Appendix 12)
The change of the gap is performed by at least one of movement of a die constituting the coating apparatus, expansion and contraction of the tip of the die, change in angle of the die, or movement of a backup roll on which the substrate is placed. The manufacturing method of the electrode as described in any one.
(Appendix 13)
The first layer is coated on the substrate and dried, and then the second layer is coated, or the first layer is coated on the substrate and not dried. The method for producing an electrode according to any one of appendices 1 to 12, wherein:
(Appendix 14)
The electrode manufacturing method according to any one of appendices 1 to 13, wherein the first layer is an active material layer of the battery, the second layer is an insulating layer, and the base is a current collector.
(Appendix 15)
The said 1st layer is a manufacturing method of the electrode as described in any one of Additional remarks 1-14 currently formed on the said base material intermittently.
(Appendix 16)
The method for manufacturing an electrode according to any one of appendices 1 to 15, wherein the coating apparatus is a die coater.
(Appendix 17)
Base material,
A first layer formed on at least a part of the substrate;
At least on the first layer and the base material, and formed across the boundary portion between the first layer and the base material, the thickness is on the boundary portion, on the first layer, on the base material. The second layer, decreasing in this order,
A battery electrode characterized by comprising:
(Appendix 18)
Base material,
A first layer formed on at least a part of the substrate;
It is formed across at least the boundary portion with the base material on the first layer, and the thickness is reduced in this order in the boundary portion, on the base material, and in the region adjacent to the boundary portion on the first layer. The second layer,
A battery electrode characterized by comprising:
(Appendix 19)
The battery electrode according to appendix 17 or 18, wherein the first layer is a battery active material layer, the second layer is an insulating layer, and the base material is a current collector.
(Appendix 20)
A transport mechanism for transporting the base material partially formed of the first layer;
A coating die for applying a material to the substrate;
A control circuit for controlling the position of the coating die;
With
The control circuit includes:
In the region before the boundary portion on the substrate, a gap between the coating device and the substrate is a first thickness corresponding to a wet thickness determined by a coating liquid discharge amount of the coating device and a moving speed of the substrate. The second layer is applied with a second gap smaller than the gap, and on the first layer, the third gap is applied by adding the thickness of the first layer to the first gap, or
Or
On the first layer, the gap between the coating device and the first layer is applied, the second layer is applied with the third gap, and the region on the first layer before the boundary portion is the third layer. The second layer is applied with a fourth gap that is smaller than the gap and larger than the thickness of the first layer, and the second layer is applied with the first gap on the substrate.
An electrode manufacturing apparatus for controlling a position of the coating die.

DESCRIPTION OF SYMBOLS 1 Lithium ion

secondary battery

10, 20 Base material 11, 21

1st layer

12, 22 2nd layer 13, 23

Liquid reservoir

14, 24

Coating apparatus

15, 25

Boundary part

16, 16 ', 26, 26', 26 ''

Gap

18, 28, 38 Thick coating film 30 Current collecting foil 32 Insulating layer 34 Coating die 39 Detector 40 Current collecting foil 56, 56 ', 56''Film thickness meter 60 Die 61 Piezoelectric body 62 Rotating shaft 63 Backup roller 100 Positive electrode 110 Positive electrode active material forming part 120 Positive electrode active material non-forming part 155 Current collecting foils 180 and 185 Insulating layer 200 Negative electrode 210 Negative electrode active material forming part 220 Negative electrode active material non-forming part 300 Die coater 301 Backup roller 302 Control circuit 350 Separator 400 Battery element 410 Positive electrode lead part 420 Negative electrode lead part 430 Positive electrode terminal 440 Negative electrode terminal 450 Exterior container 460 Inner surface layer 470 Metal layer 480 Surface layer

Claims

A method for producing an electrode, in which a second layer is applied to at least a boundary portion between the base material and the first layer with respect to the base material partially formed with a first layer,
In the region before the boundary portion on the substrate, a gap between the coating device and the substrate is a first thickness corresponding to a wet thickness determined by a coating liquid discharge amount of the coating device and a moving speed of the substrate. The second layer is coated with a second gap smaller than the gap, and the third layer is coated on the first layer by adding the thickness of the first layer to the first gap. A method for manufacturing an electrode.
2. The electrode production according to claim 1, wherein the second layer is applied on the base material before the boundary part while forming a pool of the coating liquid between the coating apparatus and the base material. Method.
The coating of the second layer is performed by changing the gap from the second gap to the third gap immediately before the boundary after coating by the second gap. Of manufacturing the electrode.
The electrode according to any one of claims 1 to 3, wherein the second gap has a distance that is 20% or more smaller than the first gap on the base material 1 mm or more before the boundary. Method.
5. The method for manufacturing an electrode according to claim 4, wherein the gap is reduced by 20% or more and 50% or less from the first gap at least 1 mm before the boundary.
The said 2nd layer is applied with the said 1st gap on the said base material, Then, the said 2nd layer is applied with the said 2nd gap in the area | region before the said boundary part. The method for producing an electrode according to one item.
A method of manufacturing an electrode, wherein a second layer is applied to at least a boundary portion between the first layer and the substrate with respect to a substrate on which a first layer is formed in part,
On the first layer, the thickness of the first layer is added to the first gap corresponding to the wet thickness determined by the coating liquid discharge amount and the moving speed of the base material. The second gap is applied with a third gap, and a fourth gap which is smaller than the third gap and larger than the thickness of the first layer in the region before the boundary on the first layer. The method for producing an electrode, wherein the second layer is applied and the second layer is applied on the substrate with the first gap.
The electrode according to claim 7, wherein the second layer is applied on the first layer before the boundary portion while forming a liquid pool of the coating liquid between the coating device and the first layer. Manufacturing method.
The method for manufacturing an electrode according to claim 7 or 8, wherein the fourth gap is a distance that is 20% or more smaller than the third gap on the first layer that is 1 mm or more in front of the boundary portion.
10. The fourth gap according to claim 7, wherein the fourth gap is a distance that is 20% or more and 50% or less smaller than the third gap on the first layer that is 1 mm or more in front of the boundary portion. Of manufacturing the electrode.
11. The method according to claim 7, wherein the second layer is applied with the third gap on the first layer, and then the second layer is applied with the fourth gap in a region before the boundary. A method for producing the electrode according to claim 1.
The gap is changed by at least one of movement of a die constituting the coating apparatus, expansion and contraction of the tip of the die, change in angle of the die, or movement of a backup roll on which the substrate is placed. The manufacturing method of the electrode as described in any one of these.
The first layer is coated on the substrate and dried, and then the second layer is coated, or the first layer is coated on the substrate and not dried. The manufacturing method of the electrode as described in any one of Claim 1 to 12 which coats.
The method for producing an electrode according to any one of claims 1 to 13, wherein the first layer is a battery active material layer, the second layer is an insulating layer, and the base is a current collector.
The method for producing an electrode according to any one of claims 1 to 14, wherein the first layer is intermittently formed on the base material.
The electrode manufacturing method according to any one of claims 1 to 15, wherein the coating apparatus is a die coater.
Base material,
A first layer formed on at least a part of the substrate;
At least on the first layer and the base material, the boundary between the first layer and the base material is formed, and the thickness is on the boundary portion, the first layer, and the base material. The second layer, which decreases in order,
A battery electrode characterized by comprising:
Base material,
A first layer formed on at least a part of the substrate;
It is formed across at least the boundary portion with the base material on the first layer, and the thickness is reduced in this order in the boundary portion, on the base material, and in the region adjacent to the boundary portion on the first layer. The second layer,
A battery electrode characterized by comprising:
The battery electrode according to claim 17 or 18, wherein the first layer is a battery active material layer, the second layer is an insulating layer, and the base is a current collector.
A transport mechanism for transporting the base material partially formed of the first layer;
A coating die for applying a material to the substrate;
A control circuit for controlling the position of the coating die;
With
The control circuit includes:
In the region before the boundary portion on the substrate, a gap between the coating device and the substrate is a first thickness corresponding to a wet thickness determined by a coating liquid discharge amount of the coating device and a moving speed of the substrate. The second layer is applied with a second gap smaller than the gap, and on the first layer, the third gap is applied by adding the thickness of the first layer to the first gap, or
Or
On the first layer, the gap between the coating device and the first layer is applied, the second layer is applied with the third gap, and the region on the first layer before the boundary portion is the third layer. The second layer is applied with a fourth gap that is smaller than the gap and larger than the thickness of the first layer, and the second layer is applied with the first gap on the substrate.
An electrode manufacturing apparatus for controlling a position of the coating die.