KR20220068741A - Device of evaluating the degree of secession of electrode active material and method of evaluating the degree of secession of electrode active material - Google Patents

Abstract

The present invention relates to an electrode active material desorption evaluation device, and an electrode active material desorption evaluation method. The electrode active material desorption evaluation device comprises: a cutting simulation device cutting an electrode of a structure where an electrode mixture layer is formed on a current collector; and a high-speed camera capturing a cutting process of the electrode.

Description

Electrode active material desorption evaluation apparatus and electrode active material desorption evaluation method

The present invention relates to an apparatus and method for evaluating the degree of desorption of an electrode active material, and more particularly, to an apparatus and method for evaluating the degree of desorption of an electrode active material using a cutting simulating device.

Recently, rechargeable batteries capable of charging and discharging have been widely used as energy sources for wireless mobile devices. In addition, the secondary battery is attracting attention as an energy source for electric vehicles, hybrid electric vehicles, etc., which have been proposed as a way to solve air pollution of conventional gasoline vehicles and diesel vehicles using fossil fuels. Accordingly, the types of applications using secondary batteries are diversifying due to the advantages of secondary batteries, and it is expected that secondary batteries will be applied to more fields and products in the future than now.

These secondary batteries are sometimes classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, etc. depending on the composition of the electrode and electrolyte. is increasing In general, secondary batteries, depending on the shape of the battery case, a cylindrical battery and a prismatic battery in which the electrode assembly is built in a cylindrical or prismatic metal can, and a pouch-type battery in which the electrode assembly is built in a pouch-type case of an aluminum laminate sheet The electrode assembly built into the battery case consists of a positive electrode, a negative electrode, and a separator structure interposed between the positive electrode and the negative electrode, and is a power generating element capable of charging and discharging. It is classified into a jelly-roll type wound with a separator interposed therebetween, and a stack type in which a plurality of positive and negative electrodes of a predetermined size are sequentially stacked with a separator interposed therebetween.

The positive electrode and the negative electrode are formed by applying a positive electrode slurry containing a positive electrode active material and a negative electrode slurry containing a negative electrode active material to a positive electrode current collector and a negative electrode current collector, respectively, and drying and rolling them. At this time, a small amount of a binder is added to the positive electrode slurry and the negative electrode slurry to prevent the active material from being detached from the current collector.

However, even in this case, the electrode active material is frequently detached from the cut portion of the current collector during the manufacturing process of the electrode, for example, in the process of cutting, notching, slitting, and laminating the electrode. As such, when the electrode active material is detached from the current collector, a problem in which the capacity of the electrode is reduced may occur, and a short circuit may occur due to the active material debris from the electrode. That is, since the degree of desorption of the electrode active material from the current collector is a major factor affecting the manufacturing processability of the battery and the performance of the battery, it is important to predict and evaluate the degree of desorption of the electrode active material. However, since there is no evaluation method for predicting the degree of desorption of the electrode active material, it is difficult to confirm the phenomenon without going through an actual process.

However, in the actual process, since most of the electrode active materials are detached due to cutting and punching, there is a problem in that it is difficult to accurately measure the adhesion of the electrode only by measuring the adhesion or peel strength.

Therefore, there is a need to develop a technology capable of predicting and evaluating the degree of desorption of the electrode active material.

Korean Patent Publication No. 10-2016-0085023

The present invention has been devised to solve the above problems, and an object of the present invention is to provide an electrode active material desorption evaluation apparatus and an electrode active material desorption evaluation method, which can reduce process loss by simply predicting whether the electrode active material is desorbed.

Electrode active material desorption evaluation device according to the present invention, a cutting simulating device for cutting an electrode having a structure in which an electrode mixture layer is formed on a current collector; and a high-speed camera for photographing the cutting process of the electrode. includes

In a specific example, the cutting simulating device includes: a first cutting member positioned under the electrode; a second cutting member positioned above the electrode and having a blade formed on a lower surface to cut the electrode, the blade having an inclination with respect to the electrode surface along the width direction (TD direction); and a gripper for fixing both ends of the electrode.

The cutting simulation device includes a cutting speed, a tension applied to the electrode by the gripper, an angle between the blade formed on the second cutting member and the electrode surface, and a first cutting member and a second cutting member based on the longitudinal direction (MD direction). At least one selected from the group consisting of a clearance between the grippers and a distance between the grippers is adjustable.

The high-speed camera may be located on one side of the electrode in the width direction.

In addition, the high-speed camera may be positioned in parallel with the electrode.

In addition, the electrode active material detachment evaluation method according to the present invention comprises the steps of: inputting an electrode having a structure in which an electrode mixture layer is formed on a current collector into a cutting simulating device; while cutting the electrode, photographing the cutting process with a high-speed camera; and determining whether the electrode detachment is defective from the photographed image or image.

Specifically, the cutting simulation device, the first cutting member located under the electrode; a second cutting member positioned above the electrode and having a blade formed on a lower surface to cut the electrode, the blade having an inclination with respect to the electrode surface along the width direction (TD direction); and grippers for fixing both ends of the electrode.

At this time, when the electrode mixture layer is lifted from the current collector during the cutting process, the electrode may be determined as defective.

In addition, the electrode active material detachment evaluation method according to the present invention may further include cutting the electrode by changing at least one of a cutting condition or an electrode manufacturing condition, and determining whether the electrode detachment is defective therefrom.

In a specific example, the cutting conditions include a cutting speed, a tension applied to the electrode by the gripper, an angle between the blade formed on the second cutting member and the electrode surface, and the first and second cutting members in the longitudinal direction (MD direction). At least one selected from the group comprising a distance between the cutting members (Clearance) and a distance between the grippers.

In addition, the electrode active material desorption evaluation method according to the present invention may further include deriving a cutting condition in which desorption of the electrode active material is minimized for each manufacturing condition of the electrode.

The step of deriving the cutting conditions in which the occurrence of desorption of the electrode active material is minimized may include deriving a correlation between the manufacturing conditions and cutting conditions of the electrode and whether the desorption of the electrode active material is defective.

In addition, the process of deriving the correlation between the manufacturing conditions and cutting conditions of the electrode and whether the electrode active material detachment is defective is changing the manufacturing conditions and cutting conditions of the electrode to measure whether the electrode active material detachment is defective, the electrode manufacturing conditions and It may include the process of building a database on whether the electrode active material detachment is defective according to the cutting conditions.

In this case, the cutting conditions for minimizing the occurrence of desorption of the electrode active material may be derived from the database.

In the electrode active material desorption evaluation method according to the present invention, the desorption degree of the electrode active material is evaluated while adjusting various cutting conditions using a simple cutting simulating device without the need to evaluate the desorption degree by putting it into an actual process after manufacturing the electrode. Desorption of the electrode active material can be improved by comparing and evaluating the degree of desorption according to variables and optimizing the process.

In addition, the present invention can minimize the occurrence of defects and process losses by predicting in advance whether the electrode active material is defective in detachment before the electrode is inserted.

1 is a block diagram showing the configuration of an electrode active material desorption evaluation apparatus according to the present invention.
Figure 2 is a schematic diagram showing the structure of the cutting simulation device according to the present invention.
3 and 4 are schematic views showing the process of cutting the electrode using the cutting simulating device according to the present invention.
5 is a flowchart illustrating the procedure of the electrode active material desorption evaluation method according to the present invention.
6 is a photograph of a cutting process of an electrode using a high-speed camera.
7 is a schematic diagram illustrating a method for determining the degree of desorption of an electrode active material in the method for evaluating desorption of an electrode active material according to the present invention.

Hereinafter, the present invention will be described in detail. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined in

In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. Also, when a part of a layer, film, region, plate, etc. is said to be “on” another part, it includes not only the case where the other part is “directly on” but also the case where there is another part in between. Conversely, when a part of a layer, film, region, plate, etc. is said to be “under” another part, it includes not only cases where it is “directly under” another part, but also cases where another part is in between. In addition, in the present application, “on” may include the case of being disposed not only on the upper part but also on the lower part.

In addition, in the present invention, the longitudinal direction (or MD direction) of the electrodes means a direction in which a straight line connecting the grippers extends (x-axis direction) with respect to the electrodes fixed between the grippers, and the width direction (TD direction) of the electrodes. ) means a direction perpendicular to the longitudinal direction on the electrode surface.

Hereinafter, the present invention will be described in detail.

1 is a block diagram showing the configuration of an electrode active material desorption evaluation apparatus according to the present invention.

Referring to FIG. 1, the electrode active material desorption evaluation device 1 according to the present invention includes a cutting simulating device 100 for cutting an electrode having a structure in which an electrode mixture layer is formed on a current collector; And a high-speed camera 200 for photographing the cutting process of the electrode; includes

As described above, in the prior art, an electrode prepared for evaluation of detachment was put into an actual process, or adhesive strength of the electrode was measured. However, in this case, the process is complicated, and there is a problem that the adhesive force of the electrode active material does not reflect the actual degree of detachment.

The electrode active material desorption evaluation apparatus according to the present invention uses a simple cutting simulating device to control various cutting conditions without the need to evaluate the desorption degree by putting it into an actual process after manufacturing the electrode. By evaluating the desorption degree of the electrode active material Desorption of the electrode active material can be improved by comparing and evaluating the degree of desorption according to variables and optimizing the process.

In addition, the present invention can minimize the occurrence of defects and process losses by predicting the degree of desorption of the electrode active material in advance before the electrode is inserted.

Hereinafter, the electrode active material desorption evaluation device according to the present invention will be described in detail.

Figure 2 is a schematic diagram showing the structure of the cutting simulation device according to the present invention, Figures 3 and 4 are schematic views showing the process of cutting the electrode using the cutting simulation device according to the present invention.

1 to 4 , the electrode active material desorption evaluation device 1 according to the present invention includes a cutting simulating device 100 for cutting the electrode 10 . Meanwhile, the electrode has a structure in which an electrode mixture layer is formed on a current collector, as will be described later.

The cutting simulating device 100 is a device having the same function as a cutting device for manufacturing unit electrodes by cutting electrodes in an actual process. The cutting simulating device 100 does not need to be as large as the actual cutting device so that the electrode 10 can be conveniently cut, and includes a minimal configuration that reflects the process for cutting the electrode for simplification and ease of evaluation. it is enough

Specifically, the cutting simulation device 100 is provided with a cutting member for cutting the electrode (10).

The cutting member includes a first cutting member 110 positioned below the electrode 10 and a second cutting member 120 positioned above the electrode 10 . The cutting members 110 and 120 have a blade shape in which a blade is formed on one side facing the electrode, and, for example, a blade made of a carbide material may be used.

In the cutting members 110 and 120 , the first cutting member 110 supports the electrode 10 under the electrode 10 . The second cutting member 120 descends from the upper portion of the electrode 10 to the electrode 10 to cut the electrode 10 . The first cutting member 110 and the second cutting member 120 are arranged to be shifted from each other in the longitudinal direction of the electrode so that the blades formed on one side thereof do not contact each other. Through this, when the second cutting member 120 descends and comes into contact with the first cutting member 110 , a shear force is applied to the electrode 10 to cut the electrode.

To this end, the cutting simulation device 100 supports the driving member 140 and the second cutting member 120 capable of driving the second cutting member 120 , and controls the movement of the second cutting member 120 . It may further include a guide member 150 for guiding. The driving member 140 may be, for example, a motor or a pneumatic cylinder. In this case, the second cutting member may be lowered by rotation of the motor or pneumatic pressure supplied by the pneumatic cylinder. Meanwhile, the guide member 150 has a pillar shape formed in a direction perpendicular to a plane formed by the electrode, and a rail on which the second cutting member can move is formed.

In the present invention, a blade is formed on a lower surface of the second cutting member 120 facing the electrode 10 to cut the electrode 10 . In this case, the blade is inclined with respect to the electrode surface along the width direction of the electrode 10 . That is, as shown in FIG. 3 , the distance from one end to the other end of the blade formed on the second cutting member 120 in the width direction increases or decreases continuously with the electrode 10 . As described above, the slope is formed on the blade formed on the second cutting member 120 , so that the second cutting member 120 makes point contact with the electrode 10 when interacting with the first cutting member 110 . It becomes possible to cut the electrode 10 easily with pressure.

In addition, the cutting simulating device 100 may include a gripper 130 for fixing both ends of the electrode. The gripper 130 includes first grippers 131 and second grippers 132 positioned on both sides of the cutting simulation device 100, and a cutting member 110 at an intermediate point between the first gripper and the second gripper. 120) is located.

On the other hand, the cutting simulation device 100 according to the present invention is designed to be able to change the dimensions and cutting conditions of the device. Specifically, the cutting simulating device 100 includes a cutting speed, a tension applied to the electrode 10 by the gripper 130 , an angle between the blade formed on the second cutting member 120 and the electrode surface, and a longitudinal direction. At least one selected from the group including the distance between the reference first cutting member 110 and the second cutting member 120 and the distance between the gripper 130 (MD direction) can be adjusted. Specific details on this will be described later.

To this end, the cutting simulating device 100 may be detachably detachable such that the first cutting member 110 or the second cutting member 120 can be replaced, and the position of the gripper 130 may be adjusted.

As will be described later, the present invention can derive cutting conditions that minimize the occurrence of detachment of the electrode active material for each electrode manufacturing condition while changing the cutting conditions and the electrode manufacturing conditions as described above.

In addition, referring to FIGS. 1 and 4 , the electrode active material desorption evaluation apparatus 1 according to the present invention further includes a high-speed camera 200 for photographing the cutting process of the electrode 10 .

The present invention progresses rapidly, and the appearance of the electrode at the moment of cutting, which is difficult to confirm with the naked eye or a general image camera, can be photographed through a high-speed camera, and through this, whether or not the electrode is detached can be predicted by examining the behavior of the electrode and the electrode mixture layer at the moment of cutting. . Specific details of the high-speed camera are known to those skilled in the art, and thus detailed description thereof will be omitted.

Meanwhile, referring to FIG. 4 , the high-speed camera 200 is located on one side of the electrode 10 . More specifically, the high-speed camera 200 is located on one side of the electrode 10 in the width direction (TD direction). In addition, the high-speed camera 200 can photograph the side of the electrode 10 by being positioned in parallel with the electrode 10 . A high-speed camera 200 is installed from one side of the electrode 10 to the electrode 10 so that the layered structure of the electrode having the electrode mixture layer formed on the current collector and the change occurring in the layered structure at the moment of cutting the electrode can be smoothly photographed. to arrange them side by side. In addition, the high-speed camera may be positioned to be spaced apart from the electrode by a predetermined interval.

In addition, the electrode active material desorption evaluation apparatus according to the present invention may further include a controller (not shown) capable of simultaneously controlling the operation of the cutting simulating device and the high-speed camera. The control unit may simultaneously control the operation of the cutting simulation device and the high-speed camera so that the high-speed camera can accurately photograph the moment when the electrode is cut.

The present invention also provides a method for evaluating electrode active material detachment.

5 is a flowchart illustrating the procedure of the electrode active material desorption evaluation method according to the present invention.

Referring to Figure 5, the electrode active material desorption evaluation method according to the present invention, the step of putting an electrode having a structure in which an electrode mixture layer is formed on a current collector into a cutting simulating device (S10); While cutting the electrode, photographing the cutting process with a high-speed camera (S20); and determining whether the electrode detachment is defective from the photographed image or image (S30).

In the electrode active material desorption evaluation method according to the present invention, the desorption degree of the electrode active material is evaluated while adjusting various cutting conditions using a simple cutting simulating device without the need to evaluate the desorption degree by putting it into an actual process after manufacturing the electrode. Desorption of the electrode active material can be improved by comparing and evaluating the degree of desorption according to variables and optimizing the process.

In addition, the present invention can minimize the occurrence of defects and process losses by predicting the degree of desorption of the electrode active material in advance before the electrode is inserted.

Hereinafter, each step of the electrode active material desorption evaluation method according to the present invention will be described in detail.

<Production of electrode>

First, an electrode to be evaluated is manufactured.

The electrode may have a structure in which an electrode mixture layer is formed by applying an electrode slurry including an electrode active material on a current collector, drying and rolling the electrode slurry.

The current collector may be a positive electrode current collector or a negative electrode current collector, and the electrode active material may be a positive electrode active material or a negative electrode active material. In addition, the electrode slurry may further include a conductive material and a binder in addition to the electrode active material.

In addition, the electrode may be a positive electrode or a negative electrode, and more specifically, may be a negative electrode in which an active material desorption issue frequently occurs.

In the present invention, the positive electrode current collector is generally made to have a thickness of 3 to 500 μm. The positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. Carbon, nickel, titanium, silver, etc. surface-treated on the surface of the can be used. The current collector may increase the adhesion of the positive electrode active material by forming fine irregularities on the surface thereof, and various forms such as a film, sheet, foil, net, porous body, foam body, and non-woven body are possible.

In the case of a sheet for a negative electrode current collector, it is generally made to a thickness of 3 to 500 μm. Such a negative current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel. Carbon, nickel, titanium, a surface-treated material such as silver, aluminum-cadmium alloy, etc. may be used. In addition, like the positive electrode current collector, the bonding strength of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and may be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven body, and the like.

In the present invention, the positive active material is a material capable of causing an electrochemical reaction, as a lithium transition metal oxide, containing two or more transition metals, for example, lithium cobalt oxide (LiCoO ₂ ) substituted with one or more transition metals. ), layered compounds such as lithium nickel oxide (LiNiO ₂ ); lithium manganese oxide substituted with one or more transition metals; Formula LiNi _1-y M _y O ₂ (wherein M = Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn or Ga, including at least one of the above elements, 0.01≤y≤0.7) Lithium nickel-based oxide represented by; Li _1+z Ni _1/3 Co _1/3 Mn _1/3 O ₂ , Li _1+z Ni _0.4 Mn _0.4 Co _0.2 O ₂ , etc. Li _1+z Ni _b Mn _c Co _{1-(b+c+d )} M _d O _(2-e) A _e (where -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2, 0≤e≤0.2, b+c+d <1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl) a lithium nickel cobalt manganese composite oxide; Formula Li _1+x M _1-y M' _y PO _4-z X _z where M = transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti, X = F, S, or N, and -0.5≤x≤+0.5, 0≤y≤0.5, 0≤z≤0.1 olivine-based lithium metal phosphate represented by), but is not limited thereto.

The negative electrode active material includes, for example, carbon such as non-graphitizable carbon and graphitic carbon; Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _1-x Me' _y O _z (Me: Mn, Fe, Pb, Ge; Me' : metal composite oxides such as Al, B, P, Si, elements of Groups 1, 2, and 3 of the periodic table, halogen; 0<x≤1;1≤y≤3;1≤z≤8); lithium metal; lithium alloy; silicon-based alloys; tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , metal oxides such as Bi ₂ O ₅ ; conductive polymers such as polyacetylene; A Li-Co-Ni-based material or the like can be used.

The conductive material is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive active material. Such a conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, graphite such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The binder is a component that assists in bonding between the active material and the conductive material and bonding to the current collector, and is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, poly propylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butyrene rubber, fluororubber, various copolymers, and the like.

<Measurement of electrode cutting and detachment failure>

When the electrode is manufactured, the step of cutting the electrode by putting the electrode into a cutting simulating device is performed.

As described above, the cutting simulating device includes a first cutting member 110 positioned under the electrode 10; a second cutting member 120 positioned on the electrode 10 and having a blade formed on the lower surface to cut the electrode, the blade having an inclination with respect to the electrode surface along the width direction (TD direction); and a gripper 130 for fixing both ends of the electrode. After both ends of the electrode are fixed between the grippers 130 by the grippers 130 , the electrode is cut by the descending movement of the second cutting member 120 .

In this process, the first cutting member 110 or the second cutting member 120 rubs against the electrode 10, and the electrode 10 is bent by shear force. In this process, the electrode active material in the electrode mixture layer is collected. detached from the whole. In particular, detachment mainly occurs in a portion in direct contact with the blade formed on the second cutting member 120 .

In the present invention, the tally shape appearing in the cutting process as described above is photographed by a high-speed camera. Then, it is determined whether the detachment of the electrode is defective from the photographed image or image. Here, the poor detachment of the electrode refers to a case in which the degree of detachment of the electrode active material deviates from a predetermined standard.

6 is a photograph of a cutting process of an electrode using a high-speed camera.

In the present invention, when the electrode mixture layer is lifted from the current collector during the cutting process, the electrode is determined to be defective. That is, when the electrode mixture layer on the current collector is attached to the current collector without any gaps during the cutting process as shown in FIG. When the electrode mixture layer is lifted from the current collector and a gap occurs between the current collector and the electrode mixture layer, the electrode is judged as defective. As described above, even when the electrode having the same condition as the electrode determined to be defective is put into an actual process, it can be predicted that a defect will occur. That is, in the present invention, since the cutting process is photographed with a high-speed camera, and whether detachment is defective only by analyzing the captured image or image, the process of measuring the area of the detached portion or measuring the amount of the detached active material is unnecessary.

In addition, the electrode active material detachment evaluation method according to the present invention may further include cutting the electrode by changing at least one of a cutting condition or an electrode manufacturing condition, and determining whether the electrode detachment is defective therefrom. From this, it is possible to predict whether there is a detachment defect according to various cutting conditions and manufacturing conditions of the electrode.

On the other hand, in the present invention, the cutting condition is related to the size or operation of the cutting simulation equipment. Specifically, the cutting conditions are the cutting speed, the tension applied by the gripper to the electrode, the angle between the blade formed on the second cutting member and the electrode surface, and the first cutting member and the second cutting based on the longitudinal direction (MD direction). At least one selected from the group consisting of a distance between members and a distance between grippers.

Specifically, the cutting speed refers to a descending speed when the second cutting member 120 positioned above the electrode 10 comes into contact with the electrode 10 .

In addition, the tension applied to the electrode 10 by the gripper 130 is the degree to which the electrode 10 is pulled taut by the grippers 130 positioned at both ends of the electrode 10 to fix the electrode. means

In addition, referring to FIG. 4 , on the blade formed on the second cutting member 120 , a slope is formed at a predetermined angle θ as described above, so that the second cutting member 120 and the first cutting member 110 are mutually Upon action, it may induce point contact with the electrode. In the present invention, optimal cutting conditions can be derived while adjusting the angle θ formed by the inclination of the blade formed on the second cutting member 120 with the electrode surface.

On the other hand, the distance between the first cutting member 110 and the second cutting member 120 is also referred to as clearance, and as shown in FIG. 3 , refers to a distance d ₁ based on the longitudinal direction (MD direction). do. As described above, the first cutting member 110 and the second cutting member 120 are displaced in the longitudinal direction so that their ends do not collide with each other in order to apply a shear force to the electrode. Referring to FIG. 3 , the first cutting member The distance between the member 110 and the second cutting member 120 means a distance between each cutting member that is positioned to be displaced.

In addition, the distance between the grippers 130 means a distance d ₂ between the first and second grippers fixing both ends of the electrodes.

Meanwhile, in the present invention, the electrode manufacturing conditions include all conditions in the electrode manufacturing process. For example, the electrode manufacturing conditions include the composition of the electrode mixture layer, the drying conditions of the electrode and the thickness of the electrode, and the electrode It may include at least one or more of the rolling conditions of

<Deduction of cutting conditions that minimize the occurrence of detachment>

In addition, the present invention may further include the step of deriving cutting conditions that minimize the occurrence of detachment of the electrode active material for each manufacturing condition of the electrode. For example, the step of deriving a cutting condition in which the occurrence of desorption is minimized may be a step of deriving a reference value in which the occurrence of desorption is minimized for each electrode manufacturing condition and cutting condition.

In a specific example, deriving the cutting conditions for minimizing the occurrence of desorption of the electrode active material according to the manufacturing conditions of the electrode includes deriving a correlation between the manufacturing conditions and cutting conditions of the electrode and whether the electrode active material is defective. Here, the correlation between the manufacturing conditions and cutting conditions of the electrode and whether the electrode active material detachment is defective means the tendency of the electrode active material detachment defect depending on the electrode manufacturing conditions and the cutting conditions.

In addition, the process of deriving the correlation between the electrode manufacturing conditions and cutting conditions and the degree of desorption of the electrode active material is to change the manufacturing conditions and cutting conditions of the electrode to measure whether the electrode active material is defective while measuring the electrode manufacturing conditions and cutting conditions. It includes the process of building a database on whether the electrode active material detachment is defective. To this end, a plurality of electrodes are manufactured by varying the composition of the electrodes, and the electrodes are cut while changing cutting conditions for an electrode having a specific composition, and in this process, the cutting process is photographed with a high-speed camera, and then from the captured image or video. Defects can be determined. The results may be accumulated in a storage system such as a memory, and the database may be recorded as visual data such as tables or graphs. In this case, it is desirable to perform measurement for as many electrodes as possible for measurement accuracy.

Desorption of the electrode active material for each electrode manufacturing condition is minimized and cutting conditions may be derived from the database. Specifically, it is possible to set a reference value for minimizing detachment for each electrode manufacturing condition and cutting condition from the database. The reference value may be set, for example, from a cutting condition when a high-speed camera photographing result is determined to be a good product.

As described above, the cutting conditions are the cutting speed, the tension applied to the electrode by the gripper, the angle between the blade formed on the second cutting member and the electrode surface, and the first cutting member and the second cutting member in the longitudinal direction (MD direction). 2 It may be at least one selected from the group including a distance between the cutting members (Clearance) and a distance between the grippers.

Hereinafter, examples will be given to help the understanding of the present invention be described in detail. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the following examples. The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

Example 1

<Electrode manufacturing>

97.5 parts by weight of artificial graphite and natural graphite (weight ratio: 90:10) functioning as an anode active material, 1.4 parts by weight of styrene-butadiene rubber (SBR) functioning as a binder, 1.1 parts by weight of carboxymethyl cellulose (CMC) , a negative electrode mixture was prepared. A negative electrode slurry was prepared by dispersing this negative electrode mixture in ion-exchanged water functioning as a solvent. This slurry was coated on both sides of a copper foil having a thickness of 8 μm. Thereafter, the electrode was dried through an infrared heater (MIR), and the dried electrode was compressed to prepare an electrode 10 having an electrode mixture layer 11 formed thereon as shown in FIG. 7 . The thickness of the final electrode was 217 μm.

<Determining whether the electrode is cut or defective>

The electrode was cut in the direction (A) perpendicular to the longitudinal direction (MD direction) as shown in FIG. 7 using the cutting device shown in FIGS. 2 to 4 . At this time, the cutting speed was 0.12 m/s, the angle between the blade formed on the second cutting member and the electrode surface was 1°, and the distance between the grippers was 22 mm.

In addition, during the cutting process, a high-speed camera was used to photograph the cutting process. The high-speed camera used Photron's Fastcam Mini UX100, and the cutting process was photographed at a speed of 2000 fps. Afterwards, it was determined whether the detachment was defective from the photographed image, and the case as shown in (a) of FIG. The results are shown in Table 2.

Examples 2 to 10

Electrodes were manufactured by varying the manufacturing conditions of the electrode, specifically, the contents of SBR and CMC in the electrode mixture layer, and different drying conditions and thickness of the electrode. The conditions according to each Example are shown in Table 1 below. At this time, in Table 1, the electrodes according to Examples 7 and 8 are two-stage rolled electrodes, meaning that the rolling process is performed twice, and specifically, rolling 50 to 90% of the target thickness in the primary rolling It refers to an electrode that has undergone a process of rolling to reach the target thickness in the secondary rolling immediately after the second rolling.

Content of active material/SBR/CMC (parts by weight) dry conditions Electrode thickness (㎛) Example 1 97.5/1.4/1.1 MIR 217 Example 2 97.5/1.4/1.1 MIR 217 Example 3 97.5/1.4/1.1 hot air dry 217 Example 4 95.7/3.2/1.1 MIR 217 Example 5 95.7/3.2/1.1 hot air dry 208 Example 6 95.7/3.2/1.1 hot air dry 217 Example 7 95.7/3.2/1.1 hot air dry 1st rolling: 217
Second rolling: 208 Example 8 95.7/3.2/1.1 hot air dry 1st rolling: 222
Second rolling: 208 Example 9 95.5/3.2/1.3 MIR 217 Example 10 95.5/3.2/1.3 hot air dry 217

In addition, after cutting the electrodes according to Examples 2 to 10 in the same manner as in Example 1, it was determined whether the electrode was defective. The results are shown in Table 2.

Experimental example

For the electrodes according to Examples 1 to 10, the amount of desorption of the electrode active material after cutting was measured. The desorption amount of the electrode active material is the weight of the desorbed electrode active material compared to the length of the portion where the desorption occurs, and may be calculated as in Equation 1 below.

[Equation 1]

Desorption amount measurement results are shown in Table 2 below.

bad or not Desorption amount (mg/m) Example 1 error 142.7 Example 2 error 168.4 Example 3 error 167.2 Example 4 Good 2.3 Example 5 Good 28.8 Example 6 Good 27.1 Example 7 Good 16.2 Example 8 Good 19.3 Example 9 Good 0.8 Example 10 Good 6.3

Referring to Table 2, Examples 1 to 3 determined to be defective by the electrode active material desorption evaluation device according to the present invention exceeded 100 mg/m in all the desorption amounts, and Examples 4 to 10 determined to be good products had a desorption amount of 50 mg It can be seen that the amount of desorption is less than /m, which is very small compared to Examples 1 to 3.

In addition, the present invention can derive a cutting condition in which the detachment of the active material is minimized for each manufacturing condition of the electrode based on whether such detachment is defective.

That is, in the present invention, the electrode active material desorption evaluation apparatus according to the present invention uses a simple cutting simulating device without the need to evaluate the desorption degree by putting the electrode into an actual process after manufacturing the electrode, while adjusting various cutting conditions, the desorption degree of the electrode active material By evaluating the degree of desorption according to various process variables, it is possible to compare and evaluate the degree of desorption, and to improve desorption of the electrode active material through process optimization. In addition, the present invention can minimize the occurrence of defects and process losses by predicting the degree of desorption of the electrode active material in advance before the electrode is inserted.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. Accordingly, the drawings disclosed in the present invention are for explanation rather than limiting the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these drawings. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Meanwhile, in this specification, terms indicating directions such as up, down, left, right, front, and back are used, but these terms are for convenience of explanation only, and may vary depending on the location of the object or the position of the observer. It is self-evident that

1: Electrode active material desorption evaluation device
10: electrode
11: electrode mixture layer
100: cutting simulation device
110: first cutting member
120: second cutting member
130: gripper
131: first gripper
132: second gripper
140: drive member
150: guide member
200: high-speed camera

Claims (14)

A cutting simulating device for cutting an electrode having a structure in which an electrode mixture layer is formed on a current collector; and
A high-speed camera for photographing the cutting process of the electrode; Electrode active material desorption evaluation device comprising a.
According to claim 1,
The cutting simulating device,
a first cutting member positioned under the electrode;
a second cutting member positioned above the electrode and having a blade formed on a lower surface to cut the electrode, the blade being inclined with respect to the electrode surface in a width direction (TD direction); and
An electrode active material detachment evaluation device including a gripper for fixing both ends of the electrode.
3. The method of claim 2,
The cutting simulating device,
Cutting speed, the tension applied to the electrode by the gripper, the angle between the blade formed on the second cutting member and the electrode surface, and the distance between the first cutting member and the second cutting member in the longitudinal direction (MD direction) (Clearance) And at least one selected from the group comprising the distance between the grippers is adjustable electrode active material detachment evaluation device.
According to claim 1,
The high-speed camera is an electrode active material detachment evaluation device located on one side of the width direction of the electrode.
5. The method of claim 4,
The high-speed camera is an electrode active material detachment evaluation device positioned in parallel with the electrode.
Putting an electrode having a structure in which an electrode mixture layer is formed on a current collector into a cutting simulating device;
while cutting the electrode, photographing the cutting process with a high-speed camera;
An electrode active material detachment evaluation method comprising the step of determining whether the electrode detachment is defective from the photographed image or image.
7. The method of claim 6,
The cutting simulating device,
a first cutting member positioned under the electrode;
a second cutting member positioned above the electrode and having a blade formed on a lower surface to cut the electrode, the blade being inclined with respect to the electrode surface in a width direction (TD direction); and
An electrode active material detachment evaluation method comprising a gripper for fixing both ends of an electrode.
7. The method of claim 6,
An electrode active material detachment evaluation method for judging the electrode as defective when the electrode mixture layer is lifted from the current collector during the cutting process.
8. The method of claim 7,
The electrode active material detachment evaluation method further comprising cutting the electrode by changing at least one of the cutting conditions or the electrode manufacturing conditions, and determining whether the electrode detachment is defective therefrom.
10. The method of claim 9,
The cutting conditions are the cutting speed, the tension applied by the gripper to the electrode, the angle between the blade formed on the second cutting member and the electrode surface, and the distance between the first cutting member and the second cutting member in the longitudinal direction (MD direction). An electrode active material detachment evaluation method which is at least one selected from the group comprising a distance (Clearance) and a distance between the grippers.
8. The method of claim 7,
The electrode active material desorption evaluation method further comprising the step of deriving a cutting condition that minimizes the occurrence of desorption of the electrode active material for each manufacturing condition of the electrode.
12. The method of claim 11,
The step of deriving a cutting condition that minimizes the occurrence of desorption of the electrode active material is,
An electrode active material desorption evaluation method, comprising the process of deriving a correlation between manufacturing conditions and cutting conditions of an electrode and whether or not the electrode active material detachment is defective.
13. The method of claim 12,
The process of deriving the correlation between the manufacturing conditions and cutting conditions of the electrode and whether the electrode active material is defective or not,
An electrode active material detachment evaluation method comprising the process of constructing a database on whether electrode active material detachment is defective according to electrode manufacturing conditions and cutting conditions while measuring whether electrode active material detachment is defective by changing electrode manufacturing conditions and cutting conditions.
14. The method of claim 13,
The cutting conditions for minimizing the occurrence of desorption of the electrode active material for each electrode manufacturing condition are the electrode active material desorption evaluation method derived from the database.

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