JP2019192361A - Manufacturing method of electrode sheet for lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode sheet which is less likely to cause a defect during manufacturing. A method for manufacturing an electrode sheet in which an active material layer 1b is formed on a sheet-shaped current collector foil 1a is such that a slurry containing an active material is intermittently applied onto the sheet-shaped current collector foil 1a to form a slurry. Forming on the current collector foil 1a, a coating step of winding the current collector foil along the winding direction while alternately forming the application region and the non-application region of the sheet current collector foil in the winding direction. And a compression step of compressing the formed active material layer 1b in the thickness direction. The compression step includes compressing the active material layer 1b from the formation start point 1b1 side toward the formation end point side in the formation direction of the active material layer 1b in the coating step. [Selection diagram] Fig. 3

Description

  The present invention relates to a method for producing an electrode sheet for a lithium ion secondary battery.

  Secondary batteries, which are a type of electrochemical device, are widely used as power sources for portable electronic devices such as mobile phones, digital cameras, laptop computers, vehicle power sources, and household power sources. The electrochemical device has an electrode laminate in which two types of electrode sheets (a positive electrode sheet and a negative electrode sheet) are laminated via a separator. Each electrode sheet is obtained by forming an active material layer on a metal current collector foil.

  In particular, due to the increasing demand for electric vehicles based on recent environmental problems, it is required to increase the energy density and capacity of the secondary battery that is the driving source. A battery having a stacked shape that can be easily increased in size is selected.

An electrode for a secondary battery is produced from an electrode sheet obtained by applying a slurry containing an active material on a sheet-like current collector foil such as aluminum or copper and drying it. Specifically, a current collector foil having an active material layer formed by slurry application and drying is temporarily wound into a roll, and then the current collector foil is cut into a predetermined length to produce a plurality of electrode sheets. ing. The application method of the slurry containing an active material can be divided roughly into an intermittent coating method and a continuous coating method.
When the electrode area is increased in the laminated battery described above, a current collecting area formed by applying a slurry containing an active material to a sheet-like current collecting foil and a non-application area where no slurry is applied are collected. In many cases, an electrode sheet produced by an intermittent coating method that is alternately formed at a predetermined interval in the winding direction of the foil is used.

  In addition, since the electrode used for the secondary battery designed to have a high energy density needs to compress the active material layer at a high density, it is often pressure-molded by applying a larger pressure. There is a tendency to reduce the thickness.

JP 2004-214140 A JP 2003-223899 A Japanese Patent No. 4284760 JP 2002-124249 A JP 2003-208890 A JP 2007-172878 A

  In a method for producing an electrode sheet of an electrochemical device (for example, a lithium ion secondary battery) that has been widely spread in recent years, as described in Patent Documents 1 to 6, active materials are respectively provided on both surfaces of a sheet-like current collector foil. After forming the layer, a press (rolling) process is performed to compress the active material layer formed on the current collector foil in the thickness direction. Thereby, the electrode sheet which has an active material layer of desired density and thickness on both surfaces of current collection foil can be formed.

  When manufacturing an electrode sheet having active material layers on both sides of the current collector foil, a slurry containing the active material is applied to both sides of the current collector foil. When slurry is applied to the current collector foil using the intermittent coating method described above, it may rise locally and become thick at the application start point, that is, the active material layer formation start point (start end). . If pressing (rolling) is performed in this state, the active material layer may be cracked or chipped in the thick portion of the active material layer. Therefore, in the method described in Patent Document 1, the start end portion of one surface of the current collector foil and the start end portion of the other surface are positioned 0.5 to 2.9 mm apart in the length direction of the current collector foil. Thus, the slurry application start point is shifted on both sides of the current collector foil. Thereby, the positions of the swells (starting ends) of the active material layers on both sides of the current collector foil are shifted in the length direction. As a result, it is possible to avoid a situation in which the bulges on both sides of the current collector foil are pressed at the same time, and since there is no portion where extremely high pressure is applied during pressing, the active material layer is not easily cracked or chipped. In the methods described in Patent Documents 2 to 4, the traveling direction of the current collector foil when the active material is applied to one surface of the current collector foil, and the current collector foil when the active material is applied to the other surface The direction of travel is opposite. As a result, since the start end of one surface of the current collector foil and the start end of the other surface are located apart in the length direction of the current collector foil, the same effect as in Patent Document 2 is obtained, and the negative electrode It is possible to suppress a decrease in the adhesion strength between the active material layer of the negative electrode and the current collector foil due to the rising of the starting end portion of the active material layer.

  In the method described in Patent Document 5, the density of the raised start end portion of the active material layer is set to 1.02 to 1.50 times the density other than the start end portion. In the configuration described in Patent Document 6, the density of the active material layer of the positive electrode decreases from the start end portion toward the end portion, and the density of the active material layer of the negative electrode increases from the start end portion toward the end portion.

  According to the methods described in Patent Documents 1 to 4, an extremely high pressure is not applied to a part of the current collector foil and the active material layer, and the possibility that the active material layer is greatly damaged is reduced. However, this alone does not eliminate the manufacturing defects of the electrode sheet. For example, a fragment of the active material may adhere to the current collector foil in the non-coated area, causing problems. Further, in the method described in Patent Document 5, since the raised end portion of the active material layer is particularly strongly compressed, the possibility that the active material layer is damaged is rather high. In the method described in Patent Document 6, the depth of discharge is balanced in a state where the positive electrode and the negative electrode are stacked. However, no consideration is given to the possibility of breakage during the manufacture of the individual electrodes themselves (particularly the compression process). Thus, it is desired to more reliably suppress the occurrence of problems such as breakage and scattering of the active material layer during the production of individual electrodes.

  Then, the objective of this invention is providing the manufacturing method of the electrode sheet for lithium ion secondary batteries with a low possibility of producing a malfunction at the time of manufacture.

  An electrode sheet manufacturing method in which an active material layer is formed on a sheet-shaped current collector foil according to the present invention includes intermittently applying a slurry containing an active material on a sheet-shaped current collector foil, An application step of winding the current collector foil along the winding direction while alternately forming the non-application areas in the winding direction of the sheet-shaped current collector foil, and an active material layer formed on the current collector foil A compression step for compressing the active material layer in the thickness direction, wherein the compression step compresses the active material layer from the formation start point side to the formation end point side in the formation direction of the active material layer in the coating step. including.

  According to the present invention, there is a low possibility of occurrence of problems during the production of the electrode sheet.

It is a front view which shows typically the first half of the application | coating process of the manufacturing method of the electrode sheet of one Embodiment of this invention. It is a front view which shows typically the second half of the application | coating process of the manufacturing method of the electrode sheet shown to FIG. 1A. It is a front view which shows typically the compression process of the manufacturing method of the electrode sheet shown to FIG. 1A, 1B. It is a front view which shows typically the state which the malfunction by the failure | damage of the active material layer in a compression process generate | occur | produced. It is a front view which shows the compression process of the 1st Embodiment of this invention. It is a front view which shows compression of the 1st step of the compression process of the 2nd Embodiment of this invention. It is a front view which shows the state following FIG. 4A. It is a front view which shows compression of the 2nd step of the compression process of the 2nd Embodiment of this invention. It is a front view which shows the state following FIG. 4C. It is a graph which shows the relationship between the linear pressure of a compression process, and the density of the compressed active material layer.

Embodiments of the present invention will be described below with reference to the drawings.
The electrode sheet manufactured by the method according to the present invention is used for a lithium ion secondary battery. A lithium ion secondary battery has a configuration in which an electrode laminate in which two types of electrode sheets (a positive electrode and a negative electrode) are alternately laminated via a separator is housed in an outer container together with an electrolytic solution. About the specific manufacturing method of this electrode sheet, only about the negative electrode 1 is shown in FIGS. However, although illustration and description are omitted, the positive electrode can be manufactured in the same manner as the negative electrode 1.

  As shown in FIG. 1A, a slurry containing an active material is applied to one surface of a sheet-like current collector foil 1a to form an active material layer 1b. Then, as shown in FIG. 1B, the same slurry is applied to the other surface of the current collector foil 1a to form the active material layer 1b. Thus, the active material layer 1b is formed on both surfaces of the current collector foil 1a (application process). At this time, the current collector foil 1a formed with the active material layer 1b by slurry application and drying is temporarily wound into a roll shape, and then the current collector foil 1a is cut into predetermined lengths to form a plurality of electrode sheets (negative electrodes). 1) is produced. The position of the start end portion 1b1 of the active material layer 1b in the winding direction of the current collector foil 1a is formed to be substantially the same position on both surfaces of the current collector foil 1a.

  Thus, after performing the application | coating process shown to FIG. 1A and 1B, a compression process is performed. In the compression step, as shown in FIG. 1C, the current collector foil 1a and the active material layer 1b are sandwiched between a pair of rollers 2, and the roller 2 is rotated to feed out the current collector foil 1a and the active material layer 1b. At this time, since the distance between the pair of rollers 2 is constant, the active material layer 1b sandwiched between the pair of rollers 2 is compressed by being pressed from both rollers 2, and has a predetermined density (for example, 1.. 66 g / cc). In such an electrode sheet manufacturing method, in the present embodiment, from the active material application start point in the application process, that is, from the active material layer formation start point (start end), the active material application end point, that is, the active material layer. The direction toward the formation end point (terminal part) of the material coincides with the direction from the compression start point (press start point) of the active material layer in the compression process toward the compression end point (press end point) of the active material layer. Yes. Thereby, generation | occurrence | production of the inferior goods at the time of manufacture of an electrode sheet can be suppressed. The reason and technical significance of the present invention will be described below.

The electrode 1 used for a lithium ion secondary battery is generally manufactured by compressing the active material layer 1b until a desired density is obtained after the active material layer 1b is formed on the current collector foil 1a. Therefore, when manufacturing many electrodes 1, the active material layer 1b is formed continuously or intermittently on the sheet-like current collector foil 1a. At this time, it locally rises and becomes thicker at the start point (starting end) of the active material layer. For example, the length of the application region of each active material layer 1b intermittently formed in the coating step is 227 mm, so that the basis weight is 12.7 mg / cm ^2, the roller 2 for feeding a sheet-like collector foils 1a The rotation speed was 30 m / min. A slurry containing water as a dispersion medium and styrene-butadiene copolymer rubber (SBR) as a binder is used at 25 ° C. and a shear rate of 3 using a B-type viscometer (manufactured by Brookfield Co., Ltd.). The viscosity when measured under the condition of .4 s ⁻¹ was adjusted to be in the range of 5000 mPa · s to 10000 mPa · s. Under these conditions, when slurry is applied using a die coater, the average thickness within a range of 10 mm corresponding to 4.4% of the length of the application region of each active material layer 1b from the formation start point is applied. It becomes thicker in the range of 2% or more and 5% or less than the average thickness in the range exceeding 10 mm from the formation start point in the process (in each drawing, the rise of the formation start point is exaggerated for easy understanding) ) Thereafter, the current collector foil 1a on which the active material layer 1b is formed is conveyed to a pressure member (for example, a pair of rollers 2), and is pressed and compressed on the active material layer 1b. Thus, a defect may occur in the compression process in which the active material layer 1b is pressurized and compressed. When the present applicant considered the cause of the occurrence of this defect, as schematically shown in FIG. 2, a part of the active material is chipped and scattered when pressed to the pressing member (for example, the roller 2). A problem has been found that it may adhere to the current collector foil 1a in the non-application area. Thus, when the active material layer piece 1b2 (see FIG. 2) adheres to the current collecting foil 1a in the non-application region, the other current collecting foil overlapping the current collecting foil 1b may be damaged, or the required size, shape, The electrode 1 having performance may not be manufactured. 2D, the active material layer 1b located on the lower side of the drawing is omitted for convenience.

  On the other hand, the present applicant devised the feeding direction of the current collector foil 1a on which the active material layer 1b to be pressed in the compression process was devised, so that the active material layer 1b was pressed when the active material layer 1b was pressurized. It has been found that it is possible to avoid a part of the particles from scattering and adhering to the current collector foil 1a in the non-application area. This point will be described by taking the negative electrode 1 shown in FIG. 2 as an example. Usually, when the active material layer 1b is formed on the sheet-like current collector foil 1a, the current collector foil 1a is generally wound into a roll and stored. In the subsequent compression step, the roll-shaped current collector foil 1a is fed out again and conveyed to a pressure member (for example, a pair of rollers) 2 to perform press working. That is, when the current collector foil 1a that has been wound up in order from the start end 1b1 side in the coating process is fed out, the current collection foil 1a is fed out in order from the end side. Therefore, the pressure member 2 is supplied from the terminal end side and is sequentially compressed from the terminal end side of the current collector foil 1a toward the start end part 1b1 side. At this time, when the pressing member 2 comes into contact with the raised portion of the start end portion 1b1 of the active material layer 1b and a part of the active material layer 1b is chipped and scattered, the start end portion 1b1 of the active material layer 1b and the next active portion 1b1 are separated. The active material layer piece 1b2 adheres on the current collector foil 1a in the non-application region between the end portion of the material layer 1b. In this way, the active material layer piece 1b2 adheres on the current collecting foil 1a in the non-application region, thereby causing the above-described problems. At this time, the ratio (defect rate) at which defects in the adhesion of the active material pieces to the non-application area occurred was about 39%. Even if the bulge of the starting end 1b1 is reduced to a comparatively gentle shape, the active material piece adhesion to the non-applied area of about 17% occurs according to this method.

  On the other hand, in this embodiment, after the active material layer 1b is formed on the sheet-like current collector foil 1a, the current collector foil 1a is wound up in a roll shape, and then the current collector foil 1a is temporarily wound to be secondary. A roll (second roll) is formed. Then, the current collector foil 1 a is fed out from the second roll and supplied to the pressing member 2. Thus, by adding a step of rewinding the current collector foil 1a, it is possible to supply the pressurizing member 2 in order from the start end 1b1 side in the coating step and perform press working. In this case, as shown in FIG. 3, when the pressing member 2 comes into contact with the raised portion of the start end portion 1b1 of the active material layer 1b and a part of the active material layer 1b is chipped and scattered, The active material layer 1b2 adheres not on the electric foil 1a but on the active material layer 1b in the application region. That is, according to this method, since the active material layer piece 1b2 does not adhere on the current collector foil 1a in the non-application area, the above-described problems can be avoided. Further, since the portion where the active material piece 1b2 is attached is subjected to press working after that, the active material layer piece 1b2 is attached on the active material layer 1b in the application region, and the thickness of the active material layer 1b is locally increased. Even if it increases slightly, there is not much influence. Thus, in this embodiment, the process of temporarily rewinding the current collector foil 1a wound up in a roll shape is added, and a defect occurs due to the chipping of the raised active material layer 1b of the start end 1b1. Can be suppressed. In addition, the same effect is acquired by performing the same process also in a positive electrode.

More specific examples of the manufacturing method of the electrode 1 of the present invention described above will be described. In this embodiment, the negative electrode 1 for an electrochemical device such as a secondary battery is manufactured. The processing conditions (condition 1) of the example are as follows. The current collector foil 1a is a copper foil having a thickness of 8 μm. The active material layer 1b generally includes an active material, a conductive agent (not shown), and a binder. In one example, the active material includes natural graphite, the conductive agent includes carbon black in which primary particles of about 30 nm are aggregated in a chain, and the binder is SBR (styrene-butadiene copolymer rubber) and CMC (carboxymethylcellulose powder, Japan Sunrose (registered trademark) MAC series manufactured by Paper Industries Co., Ltd.). Their compositions are 96.4 wt% for the active material, 0.4 wt% for the conductive agent, 2 wt% for SBR, and 1 wt% for CMC. The basis weight is 11.15 mg / cm ² and the density of the active material layer 1b is 1.55 g / cc.

In another example, an electrode was manufactured under the following processing conditions (condition 2). The current collector foil 1a is a copper foil having a thickness of 6 μm. The active material includes natural graphite and artificial graphite, the conductive agent includes carbon black in which primary particles of about 30 nm are aggregated in a chain, and the binder includes SBR and CMC. Their composition is 77.1 wt% for natural graphite, 19.3 wt% for artificial graphite, 0.4 wt% for conductive agent, 1.5 wt% for SBR, and 1 wt% for CMC. The basis weight is 12.70 mg / cm ² and the density of the active material layer 1b is 1.63 g / cc.

  This time, an experiment for manufacturing the negative electrode 1 based on the condition 2 was performed. An active material layer 1b was formed by intermittently applying a slurry (mixture (active material + conductive agent + binder)) on both surfaces of a sheet-like current collector foil (copper foil) 1a. On both surfaces of the current collector foil 1a, the active material layer 1b was formed at substantially the same position in the winding direction of the sheet-shaped current collector foil. The sheet-shaped current collector foil 1a having the active material layer 1b formed on both sides in this way is wound up in a roll shape (not shown).

  And the current collection foil 1a wound up in roll shape is unwound and rewinded, and a secondary roll is formed. Then, the current collector foil is drawn out from the secondary roll, and the interval between the pair of rollers 2 shown in FIG. 1C is inserted. Since the distance between the pair of rollers 2 is kept constant, the active material layer 1b is compressed (stereoscopic press). According to this method, since the current collector foil 1a is wound up in a roll shape and then wound once and then compressed while being fed out again, the slurry application direction coincides with the compression direction. That is, the active material layer 1b is compressed from the same side (starting end side) as the starting end 1b1. As a result, as shown in FIG. 3, even if the roller 2 comes into contact with the raised portion of the starting end portion 1b1 of the active material layer 1b and the active material layer 1b is missing, it is not on the current collector foil 1a in the non-application area. Since the active material layer piece 1b2 adheres to the active material layer 1b in the application region and is pressed after the attachment, there is almost no problem. The feeding speed when the current collector foil 1a is fed from the secondary roll is 80 m / min, and the linear pressure applied from the roller 2 to the active material layer 1b is 0.36 t / cm. And the negative electrode 1 whose density of the active material layer 1b is 1.65 g / cc was obtained. After compression, when the current collector foil 1a was cut at predetermined lengths, the rate of occurrence of defective adhesion of the active material pieces to the non-coated area (defective rate) was 1.8%.

  In condition 2, a mixture of natural graphite and artificial graphite is used as the active material, but it may contain only one of them. Regardless of whether it is natural or artificial, the active material of the negative electrode 1 is preferably composed mainly of graphite, and may be amorphous carbon such as hard carbon or soft carbon. The active material may contain a metal or a metal compound (for example, Si, SiOx, Sn, etc.) capable of inserting and extracting lithium. The binder is not limited to SBR or the like, and may include an acrylic resin containing acrylic acid or methacrylic acid as a unit structure, an amide resin, or an imide resin.

  Next, as another embodiment, a method for performing the compression process in two stages will be described. In 1st Embodiment, after finishing the application | coating process and collecting the foil 1a wound up in roll shape once, it is used for the compression process. In contrast, in the present embodiment, as shown in FIGS. 4A to 4B, the negative electrode 1 is unwound and the current collector foil 1 a wound up in a roll shape is drawn out and supplied to the pressure member 2, and press working is performed. Do. However, the pressing process at this stage is such that the pressure is small and the active material layer 1b cannot be brought to a desired density (for example, the density is 1.55 g / cc). This first-stage compression is performed from the side opposite to the starting end 1b1 (terminal side) of the active material layer 1b. However, since the press working pressure is small, the active material layer 1b is not damaged, and the active material layer piece 1b2 does not adhere to the current collector foil 1a in the non-coated area.

  Then, the current collector foil 1a that has been compressed in the first stage as described above may or may not be wound again in a roll shape. In any case, as shown in FIGS. 4C to 4D, the current collector foil 1a, in which the active material layer 1b is compressed to some extent, is supplied again to the pressure member 2 to perform the second stage compression. In the second stage compression, pressing is performed from the start end 1b1 side of the active material layer 1b. In the first stage compression, the swell of the start end 1b1 is crushed and leveled to some extent, so the possibility that the start end 1b1 is missing and the active material layer piece 1b2 scatters in the second stage compression is low. Further, even if the active material layer 1b is missing in the second stage compression, the scattered active material layer pieces 1b2 adhere to the active material layer 1b in the application region, not the current collector foil 1a in the non-application region. Since it is pressed after adhesion, there is almost no problem. The active material layer 1b is brought to a desired density (for example, 1.65 g / cc) by this second stage compression.

  The graph shown in FIG. 5 shows the relationship between the linear pressure applied from the roller 2 to the active material layer 1b and the density of the active material layer 1b to be compressed in this example. Referring to this graph, it is preferable that the linear pressure is set to 0.25 t / cm in the first stage compression described above, and the linear pressure is set to about 0.36 t / cm in the second stage compression. That is, in the first stage compression, the compression is performed at a linear pressure of about 69% of the linear pressure in the second stage compression.

Next, the simplest form of the present invention will be described. In the method of the present embodiment, a slurry containing an active material is intermittently applied on a sheet-like current collector foil 1a, and a slurry application region and a non-application region are taken up in the winding direction of the sheet-like current collector foil. The active material layer 1b formed on the current collector foil 1a is compressed in the thickness direction and the coating step for forming the active material layer 1b for winding the current collector foil along the winding direction while alternately forming them. A compression step. The compression step includes compressing the active material layer 1b from the formation start point (start end) 1b1 side in the formation direction of the active material layer 1b in the coating step toward the formation end point (end end) side. According to this method, even if the active material layer piece 1b2 is scattered when the raised portion of the starting end portion 1b1 of the active material layer 1b is compressed, the active material in the application region is not on the current collector foil 1a in the non-application region. Since it adheres on the layer 1b, no problem occurs.

  The method for producing an electrode sheet according to the present invention includes intermittently applying a slurry containing an active material to a sheet-like current collector foil on the sheet-like current collector foil, and applying a slurry application region and a non-application region to the sheet. The current collecting foil is alternately formed in the winding direction, and the active material layer formed on the current collecting foil is compressed in the thickness direction while winding the current collecting foil along the winding direction. In the case of producing an electrode used for a secondary battery designed to have a high energy density by this method, an electrode sheet is provided that has a low possibility of producing a defective product and has a good yield. It becomes possible.

1 Negative electrode (electrode sheet)
1a Current collector 1b Active material layer 1b1 Start end (formation start point)
1b2 Active material layer piece 2 Roller (pressure member)

Claims (15)

An electrode sheet manufacturing method in which an active material layer is formed on a sheet-shaped current collector foil,
A slurry containing an active material is intermittently applied on the sheet-shaped current collector foil, and the slurry application area and the non-application area are alternately formed in the winding direction of the sheet-shaped current collector foil. Meanwhile, an application step of winding the current collector foil along the winding direction, and a compression step of compressing the active material layer formed on the current collector foil in the thickness direction,
The said compression process includes compressing the said active material layer from the formation start point side in the formation direction of the said active material layer in the said application | coating process toward the formation end point side, The electrode for lithium ion secondary batteries Sheet manufacturing method. In the compression step, the active material layer is compressed once,
In the coating step, the slurry is sequentially applied along the winding direction of the sheet-shaped current collector foil, and in the compression step, the winding direction of the sheet-shaped current collector foil is along the winding direction. The manufacturing method of the electrode sheet for lithium ion secondary batteries of Claim 1 with which the direction which compresses current collection foil and the said active material layer sequentially corresponds.   After completion of the coating step, the current collector foil on which the active material layer is formed is wound into a roll, and then the current collector foil on which the active material layer is formed is wound to form a secondary roll, The manufacturing method of the electrode sheet for lithium ion secondary batteries of Claim 1 or 2 which performs the said compression process with respect to the said current collection foil with which the said active material layer was formed drawn | fed out from the said secondary roll.   In the compression step, the active material layer is compressed in two stages, and in the application step, the slurry is sequentially applied along the winding direction of the sheet-like current collector foil; In the step of compression, the direction of the current collector foil and the active material layer is sequentially compressed along the winding direction of the sheet-shaped current collector foil. The direction in which the slurry is sequentially applied along the winding direction of the electric foil, and the current collector foil and the active material layer along the winding direction of the sheet-like current collecting foil in the second stage compression The manufacturing method of the electrode sheet for lithium ion secondary batteries of Claim 1 which corresponds with the direction compressed sequentially.   5. The method of manufacturing an electrode sheet for a lithium ion secondary battery according to claim 4, wherein in the first stage compression, the active material layer is compressed at a pressure of 69% or less of the pressure in the second stage compression.   The active material layers are respectively formed on both surfaces of the sheet-shaped current collector foil, and the formation start points of the active material layers on both surfaces of the current collector foil are in the winding direction of the sheet-shaped current collector foil, The manufacturing method of the electrode sheet for lithium ion secondary batteries as described in any one of Claim 1 to 5 which exists in the substantially the same position on both surfaces of current collection foil.   In the compression step, a linear pressure applied to the active material layer and the current collector foil in the central portion of the application region where the slurry is applied is 0.1 t / cm or more and 0.5 t / cm or less. 6. The method for producing an electrode sheet for a lithium ion secondary battery according to claim 6.   Each active material layer formed intermittently from the formation start point of the active material layer in the application step of the active material layer after the application step and before the compression step The thickness of the active material layer formed within the range of 4.4% of the length of the active material layer is 4 times the total length of each active material layer formed intermittently from the formation start point of the active material layer. The electrode for a lithium ion secondary battery according to any one of claims 1 to 7, wherein the electrode is thick in the range of 2% to 5% with respect to the thickness of the active material layer formed in a range exceeding 4%. Sheet manufacturing method.   The lithium ion secondary battery according to any one of claims 1 to 8, wherein the compression step is performed by inserting the current collector foil on which the active material layer is formed between a pair of rollers. A method for producing an electrode sheet. The manufacturing method of the electrode sheet for lithium ion secondary batteries as described in any one of Claim 1 to 9 which makes the density of the said active material layer into 1.65 g / cm < ³ > or more in the said compression process.   The manufacturing method of the electrode sheet for lithium ion secondary batteries as described in any one of Claim 1 to 10 which manufactures the negative electrode sheet of a lithium ion secondary battery.   The method for producing an electrode sheet for a lithium ion secondary battery according to any one of claims 1 to 11, wherein the slurry includes at least the active material and an aqueous binder.   The manufacturing method of the electrode sheet for lithium ion secondary batteries of Claim 12 whose content of the said aqueous binder is 0.01 mass part or more and 3 mass parts or less among the slurry containing the said active material.   The method for producing an electrode sheet for a lithium ion secondary battery according to any one of claims 1 to 13, wherein the slurry contains at least graphite as the active material.   The method for producing an electrode sheet for a lithium ion secondary battery according to claim 14, wherein the slurry contains at least artificial graphite as the active material.

Images