KR102156864B1 - Electrode - Google Patents

Abstract

The present application relates to an electrode and a method of manufacturing an electrode. In the present application, an electrode having excellent adhesion between the two in a structure including a current collector and an active layer and excellent in performance required by other electrodes, and a method of manufacturing such an electrode can be provided.

Description

Electrode {ELECTRODE}

The present application relates to an electrode and a manufacturing method thereof.

An electrode used for a battery or the like is generally manufactured by coating a slurry prepared using an active material, a conductive material, and a dispersion binder on a current collector, followed by drying and rolling processes to form an active layer.

If the adhesion between the current collector and the active layer is not sufficient, the performance of the electrode may be degraded, causing a problem, and accordingly, techniques for improving the adhesion between the current collector and the active layer have been proposed.

Japanese Patent Publication No. 2006-107780

The present application provides an electrode and a manufacturing method thereof. An object of the present application is to provide an electrode having excellent adhesion between the current collector and the active layer in a structure including a current collector and an active layer formed on the surface thereof, and a method of manufacturing such an electrode.

The electrode of the present application may include a current collector and an active layer formed on the surface of the current collector. Such electrodes may be, for example, plate-shaped or sheet-shaped. 1 shows a structure including a current collector 100 and an active layer 200 as an exemplary electrode. In the above structure, the current collector and the active layer may be in contact with each other.

In the present application, the term active layer means a layer after a rolling process described later, and the active layer precursor is a layer before going through the rolling process described later, and may mean a slurry layer described later or a slurry layer after a drying process. .

In the electrode of the present application, excellent adhesion between the current collector and the active layer is secured. The present inventors have confirmed that the excellent adhesion is achieved by controlling the porosity of the slurry layer dried during the drying process in the manufacturing process of the electrode leading to the formation, drying and rolling process of the slurry layer.

Accordingly, the peeling force between the current collector and the active layer in the electrode is 40 gf/15mm or more, 41 gf/15mm or more, 42 gf/15mm or more, 43 gf/15mm or more, 44 gf/15mm or more, 45 gf/15mm or more, or It may be more than 46 gf/15mm. Since the higher the value of the peeling force is, the better the adhesion between the current collector and the active layer is secured, and thus the upper limit of the above value is not particularly limited. In one example, the peeling force may be 100 gf/15mm or less, 90 gf/15mm or less, 80 gf/15mm or less, 70 gf/15mm or less, 60 gf/15mm or less, or 50 gf/15mm or less.

The peeling force is a value measured by a peeling angle of 180 degrees and a peeling speed of 0.3 m/min. For example, after cutting the electrode so that the width and length are 15 mm and 150 mm, respectively, the peel force may be measured by the peel angle and the peel rate.

Unless otherwise specifically stated in the present application, physical properties such as peeling force and impregnation to be described later were evaluated at room temperature. The term room temperature is a natural temperature that is not heated or reduced, and may be, for example, about 10°C to 30°C, about 25°C, or about 23°C.

The type of the current collector included in the electrode is not particularly limited. For example, a general type used in the manufacture of an electrode of a battery such as a secondary battery can be applied.

As the current collector, for example, stainless steel, aluminum, nickel, titanium, calcined carbon or copper may be used. In some cases, the surface of stainless steel or the like may have been subjected to surface treatment using carbon, nickel, titanium, or silver.

In some cases, fine irregularities or the like are formed on the surface of the current collector. These irregularities may help to improve adhesion to the active layer. When the surface of the current collector of the present application is roughened, the method is not particularly limited, and for example, a known method such as a mechanical polishing method, an electrolytic polishing method, or a chemical polishing method may be applied.

The current collector may have various forms such as a film, a sheet, a foil, a net, a porous body, a foam or a nonwoven fabric.

The thickness of the current collector is not particularly limited, and may be set in an appropriate range in consideration of mechanical strength, productivity, and capacity of a battery. In general, the current collector may have a thickness within the range of 3 μm to 500 μm, 10 μm to 400 μm, or 50 μm to 300 μm, but is not limited thereto.

The type of the active layer included in the electrode is also not particularly limited, and general components may be used. In the present application, it was confirmed that the desired adhesion can be secured by controlling the porosity of the active layer precursor in the process of forming the active layer using a general component.

The active layer may contain, for example, a binder. As a binder that may be included in the active layer, a general binder may be used. For example, a fluorine binder such as polytetrafluoroethylene or polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC ), cellulose binders such as hydroxypropylcellulose or recycled cellulose, polyolefin binders such as polyvinylpyrrolidone, polyethylene or polypropylene, ethylene-propylene-diene terpolymer (EPDM) or sulfonated ethylene-propylene- It may be a diene terpolymer (EPDM), a rubber-based binder such as styrene butylene rubber or fluorine rubber, or an acrylic binder.

In one example, as the binder, a fluorine binder or an acrylic binder may be used. In the present application, the term fluorine binder means a binder containing a fluorine resin such as polyvinylidene fluoride (PVDF) as a main component, and the acrylic binder is a resin containing a polymerized unit of an acrylic monomer as a main component, such as an acrylic copolymer. It may mean a binder including as a main component. In the present application, that a component is included as a main component means that the weight ratio of the component is 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, or 95 It can mean more than %. The upper limit of the ratio may be, for example, 100%.

In the present application, the term acrylic monomer means acrylic acid, methacrylic acid or a derivative thereof.

The active layer may further contain a conductive material. As the conductive material, a known one can be used without limitation. Examples of the conductive material include graphite such as natural or artificial graphite; Carbon blacks such as carbon black, acetylene black, ketjen black, panel black, furnace black, lamp black, or summer black; Conductive fibers such as carbon or metal fibers; Metal powders such as carbon fluoride, aluminum or nickel powder; Conductive whiskey such as chlorine oxide or potassium titanate; Conductive metal oxides such as titanium oxide; Alternatively, a conductive material such as a polyphenylene derivative may be used, but is not limited thereto.

The ratio of the conductive material may be selected in consideration of the performance of a target battery and the like, and is not particularly limited. In general, the conductive agent may be included in a ratio within the range of 1 to 10000 parts by weight based on 100 parts by weight of the binder.

The active layer may further include an active material. For example, when used as a positive electrode, the active layer may include a compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ) as an active material; Compounds substituted with one or more transition metals; Lithium manganese oxide mules represented by the formula Li _(1+x) Mn _(2-x) O ₄ (wherein x is a number in the range of 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ or LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxide mules such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ or Cu ₂ V ₂ O ₇ ; Ni site type lithium nickel oxide represented by the formula LiNi _1-x M _x O ₂ (wherein M is Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x is a number in the range of 0.01 to 0.3) ; Formula LiMn _2-x M _x O ₂ (wherein M is Co, Ni, Fe, Cr, Zn or Ta, x is a number in the range of 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (where M is, Lithium manganese composite oxide represented by Fe, Co, Ni, Cu or Zn); A lithium manganese composite oxide having a spinel structure such as LiNi _x Mn _2-x O ₄ (wherein x is a number in the range of 0.01 to 0.6); LiMn ₂ O ₄ ; Disulfide compounds; Alternatively, Fe ₂ (MoO ₄ ) ₃ or the like may be used, and LiNi _0.4 Mn _1.6 O ₄ may also be used. All of these active materials are known components in the field of electrode manufacturing.

When used as a negative electrode, for example, an active material capable of occluding and desorbing lithium ions may be used. Examples of such an active material include natural graphite, artificial graphite, lithium, silicon, tin, germanium or lithium titanate, or mixtures or alloys thereof.

The ratio of the active material may be selected in consideration of the performance of a target battery. In general, the active material may be included in the active layer in a ratio of 700 to 100000 parts by weight based on 100 parts by weight of the binder.

The active layer may include the binder, a conductive material, and an active material as main components. That is, the total weight ratio of the binder, the conductive material and the active material in the active layer is 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, or It may be 95% or more, and the upper limit of the ratio may be, for example, 100%.

In addition to the above-described components, the active layer may further contain various additives within a range that does not impair the physical properties of the electrode. As the additive, a stabilizer, a dispersant, a surfactant, a defoaming agent or a crosslinking agent may be exemplified, but is not limited thereto.

The thickness of the active layer is also not particularly limited, and may be adjusted to an appropriate range in consideration of the desired performance.

The present application also relates to an electrode, and relates to an electrode having a current collector and an active layer precursor formed on the surface of the current collector. As described above, the active layer precursor is a layer before the rolling process, as described above, and is a slurry layer described later or a slurry layer after a drying process.

In the above structure, the active layer precursor may have an impregnation parameter (f) defined by Equation 1 below of 0.04 or less.

[Equation 1]

V/Area = A + f×t ^0.5

In Equation 1, f is an impregnation parameter, V/Area is the ratio of the volume change (V) and the contact area change (Area) over time of the propylene carbonate droplets on the active layer precursor, and t is the propylene carbonate It is the change in time until the carbonate droplets are impregnated by 60%, and A is a constant.

In the above, the contact area is an area in which the propylene carbonate droplets are in contact with the active layer precursor.

The impregnation parameter (f) may be 0.035 or less or 0.03 or less in another example. In addition, the impregnation parameter may be, for example, about 0.001 or more, about 0.005 or more, about 0.01 or more, 0.015 or more, or about 0.02 or more. The present inventors have confirmed that when the active layer precursor exhibits the above impregnation parameter, its porosity is controlled, thereby ensuring excellent adhesion, and this adhesion is further increased through the rolling process.

The impregnability parameter is, after cutting the electrode, that is, the electrode having the current collector and the active layer precursor formed on the surface of the current collector so that the horizontal length is 1 cm and the vertical length is 4 cm, the surface of the active layer precursor About 0.3 μL of propylene carbonate solution was added dropwise, and it can be confirmed using a Drop Shape Analysis System (KRUSS, DSA100). Simultaneously with the dropping of the propylene carbonate, a PC drop video was recorded using the Drop Shape Analysis System to measure the change in contact angle, contact area, and volume of the droplet with time. do. This measurement is carried out until the droplet is completely impregnated or evaporated to make it difficult to observe the droplet with the Drop Shape Analysis System. After the observation, a graph of change over time (x-axis is time, y-axis is droplet volume/contact area) from the droplet volume and contact area is fitted according to the Washburn' equation, and the graph is impregnated with the slope (impregnability parameter: f). Can be specified as a surname parameter.

In the above formula, A is a constant that appears when a graph shows the relationship between V/Area and time (t), for example, about 0 to 0.2, about 0 to 0.15, about 0 to 0.1, or about 0 to 0.05. It can be any number within the range.

In the above structure, the peeling force between the current collector and the active layer precursor is 40 gf/15mm or more, 41 gf/15mm or more, 42 gf/15mm or more, 43 gf/15mm or more, 44 gf/15mm or more, 45 gf/15mm or more, or 46 It may be more than gf/15mm. Since the higher the value of the peeling force is, the better the adhesion between the current collector and the active layer is secured after the rolling process, and thus the upper limit of the above value is not particularly limited. In one example, the peeling force may be 100 gf/15mm or less, 90 gf/15mm or less, 80 gf/15mm or less, 70 gf/15mm or less, 60 gf/15mm or less, or 50 gf/15mm or less.

The electrode, that is, an electrode including a current collector and an active layer precursor may be applied to a subsequent process, for example, a rolling process, to form an electrode including the current collector and the active layer described above.

Therefore, in the electrode, that is, an electrode having a structure including a current collector and an active layer precursor, the same can be applied to the type or thickness of the current collector, and the content described in the active layer for components of the active layer precursor, etc. The same can be applied.

The present application also relates to a method of manufacturing the electrode. In general, the present inventors can appropriately control the porosity of the active layer precursor formed by the slurry layer by performing the drying process in multiple steps in the manufacturing process of the electrode comprising the formation, drying and rolling of the slurry layer. Accordingly, it was confirmed that the above-mentioned impregnation parameter (f) can be achieved, and thereby an electrode having excellent adhesion can be manufactured.

The method of manufacturing the electrode may include forming an active layer precursor on the current collector so that the impregnability parameter (f) described above is 0.04 or less. In the above step, the impregnation parameter of the active layer precursor may be formed to be 0.035 or less or 0.03 or less. In addition, in the above step, the impregnation parameter (f) of the active layer precursor may be formed to be about 0.001 or more, about 0.005 or more, about 0.01 or more, 0.015 or more, or about 0.02 or more.

In order to make the impregnating parameter of the active layer precursor within the above range, it is required to dry the slurry layer in multiple steps during the drying process of the slurry layer formed on the current collector.

In the above, the method of forming the slurry layer on the current collector is not particularly limited. For example, a slurry may be prepared by mixing the above-mentioned components of the active layer, that is, a binder, a conductive material, and/or an active material, and the slurry may be coated on a current collector to form a slurry. The slurry may be prepared, for example, by mixing the components, that is, a binder, a conductive material, and/or an active material in an appropriate solvent.

As the solvent, a known solvent may be used without particular limitation. For example, N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyllolactone, 1,2 -Dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethyl sulfoxide, formamide, dimethylformamide, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid tryster, trimethoxy methane, sulfolane , Methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, methyl propionate or ethyl propionate may be used, but is not limited thereto.

When preparing the slurry, the solvent may be used in a ratio such that a viscosity suitable for coating can be secured.

The method of forming the slurry layer using the prepared slurry is not particularly limited, and for example, a known coating method such as a bar coating method, a screen coating method, a doctor blade method, a dip method, a reverse roll method, a direct roll method, or a gravure method. It can be formed by applying a method.

In the above process, the amount of the slurry applied is not limited, and may be set in an appropriate range in consideration of the desired thickness.

After forming the slurry layer as described above, it is dried to form an active layer precursor. By controlling the drying conditions in the above, the above-described impregnation parameter can be satisfied.

Specifically, in order to satisfy the impregnation parameter, the drying process includes (1) preheating the current collector on which the slurry layer is formed at a temperature within the range of 150°C to 180°C, and (2) the preheating treatment after the preheating treatment. It may include at least the step of heat-treating the current collector at a temperature of 25°C to 60°C lower than the temperature. In the above, the (2) heat treatment step may be referred to as a constant rate increase step.

In the present application, as described above, the drying step of the slurry layer is subdivided into at least two steps, and the impregnation parameter of the active layer precursor may be controlled by adjusting the temperature in each step.

In the (1) preheating step, the current collector on which the slurry layer is formed is preheated, thereby providing the amount of heat at which evaporation of the solvent can be started in the subsequent (2) constant evaporation step.

The (1) preheating step is, for example, performed at any one temperature in the range of about 150°C to 180°C, any one temperature in the range of 150°C to 170°C, or any one temperature in the range of 155°C to 165°C. Can be.

The time for performing the preheating step is not particularly limited, for example, the solvent in the slurry layer is 10% by weight or less, 9% by weight or less, 8% by weight or less, 7% by weight or less, 6% by weight or less, or 5% by weight. It can be carried out until it decreases below. The lower limit of the reduction rate may be 0% by weight or more or more than 0% by weight. In other words, in the (1) preheating step, when the amount of the solvent present in the slurry layer before entering the preheating step is 100% by weight, the residual solvent is 90% by weight or more, 91% by weight or more, 92% by weight or more, It may be carried out up to a point of 93% by weight or more, 94% by weight or more, or 95% by weight or more.

Following the (1) preheating step, (2) the constant rate evaporation step is performed. The constant-rate evaporation step may be performed at a lower temperature range of 25°C to 60°C, 30°C to 55°C, or 35°C to 50°C compared to the (1) preheating step. In this way, by adjusting the temperature range of steps (1) and (2), it is possible to adjust the impregnation parameter.

The step (2) may be performed so that the solvent in the slurry layer is sufficiently removed while the temperature difference between the step (1) and the above range is left.

For example, step (2) may be performed at any one temperature within the range of 90°C to 155°C or 105°C to 130°C. In this step (2), when the amount of solvent in the initial slurry, that is, the amount of solvent before being applied to step (1) is 100% by weight, the amount of residual solvent is 5% by weight or less, 4% by weight or less, or 3% by weight. It can be carried out so that it becomes less than %. In the above, the lower limit of the amount of the residual solvent may be 1% by weight or more.

In the drying process, following the step (2), the current collector having the slurry layer formed thereon may be further subjected to a step of (3) evaporating the reduction rate.

The (3) reduction rate evaporation treatment step may be a step of maintaining the current collector having the slurry layer formed thereon at any one temperature within the range of about 95°C to 105°C or 98°C to 102°C. In the (3) evaporation treatment step, when the amount of the solvent in the initial slurry, that is, the amount of the solvent before the step (1) is 100% by weight, the amount of the residual solvent is about 0.05% to 0.8% by weight. It can be done as much as possible.

The drying step may be followed by step (3) followed by (4) removing residual solvent. The step (4) may be performed to remove the remaining solvent even after passing through the steps (1) to (3).

The (4) step may be performed at a lower temperature than the (1) preheating step. For example, step (4) may be performed at a lower temperature than step (1) within a range of 130°C to 145°C.

In step (4), when the amount of the solvent in the initial slurry, that is, the amount of the solvent before the step (1) is 100% by weight, the amount of residual solvent is 0.05% by weight or less, 0.04% by weight or less, and 0.03% by weight. % Or less, 0.02% by weight or less, or 0.01% by weight or less.

Each drying step as described above may be performed, for example, in a drying furnace including a plurality of drying zones formed by being spaced apart at predetermined intervals. In one example, the step may be performed in a drying furnace including a hot air generating unit capable of hot air drying both surfaces of a current collector on which a slurry layer is formed and 6 to 10 drying zones, but is not limited thereto.

Following the steps (1) to (4), a temperature reduction step may be performed. For example, following the step (4), a step of reducing the temperature to a temperature lower than that of the step (4) may be performed at 50°C to 100°C. This step may be performed in order to prevent structural deformation of the electrode that may occur when the electrode is suddenly exposed to the atmosphere following the drying step. The temperature reduction step may be performed by maintaining the electrode that has passed through step (4) at any one temperature within the range of 30°C to 60°C until the desired temperature is reached.

In the method of manufacturing an electrode of the present application, a rolling process may be additionally performed following the drying process. This rolling process can be carried out under conditions generally applied in the field of electrode manufacturing.

The present application also relates to a battery including the electrode as described above. The battery may be, for example, a secondary battery, specifically a lithium secondary battery. The specific structure of the battery and other configurations other than the electrode are not particularly limited, and various known configurations for the battery or the like may be selected and used without limitation.

In the present application, it is possible to provide an electrode having excellent adhesion between the two in a structure including a current collector and an active layer and excellent in performance required by other electrodes, and a method of manufacturing such an electrode.

1 is a diagram showing the structure of an exemplary electrode.

Hereinafter, the apparatus and method will be described in detail through Examples and Comparative Examples, but the scope of the apparatus and method is not limited by the following Examples.

1. Measurement of impregnation parameters

The impregnation parameter was measured in the following manner. First, the electrode (before the rolling process) including the active layer precursor prepared in Example or Comparative Example was cut to have a horizontal length of 1 cm and a vertical length of 4 cm. Then, about 0.3 μL of propylene carbonate solution was added dropwise to the surface of the active layer precursor of the electrode, and the impregnation parameter was confirmed using a Drop Shape Analysis System (KRUSS, DSA100). Specifically, the propylene carbonate droplet (PC drop) video is recorded using the Drop Shape Analysis System at the same time as the propylene carbonate is dropped, and the contact angle, the contact area, and the volume of the droplet are changed according to time. Was measured. This measurement was performed until the droplet was completely impregnated or evaporated to make it difficult to observe the droplet with the Drop Shape Analysis System. Then, based on the observation result, a graph of change over time (x-axis is time, y-axis is droplet volume/contact area) from the droplet volume and contact area over time is fitted according to the Washburn' equation, and the slope of the graph (Improvability parameter: f) can be designated as the impregnation parameter.

2. Peel force evaluation method

The electrodes are attached to slide glass having a width of 26 mm, 76 mm and 1 mm thickness, respectively, using double-sided tape. In the above, the electrode was attached to the slide glass so that the active layer or the active layer precursor was attached to the double-sided tape. The electrode at the time of attachment was cut to have a horizontal length of 15 mm and a vertical length of 150 mm, and then attached. Subsequently, the electrode was peeled at a peeling angle of 180 degrees and a peeling rate of 0.3 m/min using a texture analyzer (TA), and the peeling force between the current collector of the electrode and the active layer (or active layer precursor) was evaluated. At the time of evaluation, three identical samples (cut electrodes) were prepared, the peel force was measured, and the average value was described below.

Example 1

Preparation of slurry

As a binder, PVDF (poly(vinylidene fluoride)), conductive agent (Denka Black), and active material (LiNi0.4Mn1.6O4) are mixed with 91.5:4.3:4.2 (binder: conductive material: active material) with a total solid content of about 68% N-methylpyrrolidone (NMP) solvent was added to the degree to prepare a slurry for forming an active layer. The slurry was prepared by adding the binder, the conductive material, and the active material to a stirring vessel, and stirring at a temperature in the range of about 45°C to 50°C using a planetary mixer. After visually checking the state of the slurry, a small amount of N-methylpyrrolidone (NMP) is added to a viscosity that can be coated, and stirring is repeated to prepare a composition for forming an active layer.

Manufacture of electrodes

The slurry is coated on an aluminum current collector foil at a coating speed of about 37 m/min using a comma coater. Subsequently, in a drying furnace including 10 drying zones and a hot air generating unit capable of hot air drying the upper and lower electrodes, a preheating process sequentially (the first zone, about 150°C to 180°C, air volume 1,200 rpm to 1,600 rpm) ), constant rate evaporation process (second to fifth zones, about 105°C to 130°C, air volume 1,200 rpm to 1,600 rpm) lapse rate evaporation process (6th and 7th zones, about 90°C to 105°C, air volume 500 rpm to 1,000 rpm) and the residual solvent removal process (zones 8 and 9, about 130°C to 145°C, air volume 500 rpm to 1,000 rpm). After the residual solvent removal process, a process of reducing the temperature in a temperature range of about 40°C to 60°C (10th zone) was performed to prepare an electrode including an active layer precursor formed on the current collector. Subsequently, the electrode was rolled to prepare an electrode including an active layer.

Comparative Example 1.

When the slurry is prepared, the stirring temperature is adjusted to about 59°C, the coating speed is about 10 m/min when the slurry is coated, and the drying process is performed in an oven where the temperature is kept constant at about 120°C. Except for, an electrode was manufactured in the same manner as in Example 1.

Comparative Example 2.

When the slurry is prepared, the stirring temperature is adjusted to about 51°C, the coating speed is about 10 m/min when the slurry is coated, and the drying process is performed in an oven where the temperature is kept constant at about 120°C. Except for, an electrode was manufactured in the same manner as in Example 1.

Comparative Example 3.

When the slurry is prepared, the stirring temperature is adjusted to about 51°C, the coating speed is about 10 m/min when the slurry is coated, and the drying process is performed in an oven where the temperature is kept constant at about 140°C. Except for, an electrode was manufactured in the same manner as in Example 1.

Comparative Example 4.

When preparing the slurry, the agitation temperature was adjusted to about 51°C, the coating speed was about 10 m/min when the slurry was coated, and the drying process was performed in an oven where the temperature was kept constant at about 160°C. Except for, an electrode was manufactured in the same manner as in Example 1.

The impregnation parameters of the electrodes of Examples and Comparative Examples, and the peeling force before and after rolling are summarized in Table 1 below.

Impregnability parameter (f) Peel force before rolling Peeling force after rolling Example 1 0.0285 43.9 gf/15mm 47.2 gf/15mm Comparative Example 1 0.0454 24.3 gf/15mm 24.8 gf/15mm Comparative Example 2 0.0686 31.3 gf/15mm 35.6 gf/15mm Comparative Example 3 0.0729 32.3 gf/15mm 38.2 gf/15mm Comparative Example 4 0.0661 27.1 gf/15mm 31.8 gf/15mm

100: current collector
200: active layer

Claims (15)

delete delete delete delete delete delete delete Forming an active layer precursor on a current collector; Confirming an impregnation parameter (f) defined by Equation 1 below with respect to the active layer precursor formed on the current collector; The method of manufacturing an electrode comprising the step of rolling an active layer precursor having the impregnation parameter (f) of 0.035 or less:
[Equation 1]
V/Area = A + f×t0.5
In Equation 1, f is the impregnation parameter (f), and V/Area is the ratio of the volume change (V) and the contact area change (Area) over time of the propylene carbonate droplets on the active layer precursor, and t Is the change in time until the propylene carbonate droplet is impregnated by 60% of the initial volume, A is a constant , and the impregnation parameter (f) is the change graph of V/Area of Equation 1 over time. With the area as the y-axis and the time as the x-axis, fitting according to Washburn's equation, and designated as the slope of the graph . The method of claim 8, wherein the forming of the active layer precursor comprises: (1) preheating the current collector on which the slurry layer is formed at a temperature in the range of 150°C to 180°C, and (2) the preheating temperature after the preheating treatment. A method of manufacturing an electrode comprising the step of heat-treating the current collector on which the slurry layer is formed at a temperature lower than that of 25°C to 60°C. The method of manufacturing an electrode according to claim 9, wherein the (1) preheat treatment step is performed until the solvent in the slurry layer decreases to 10% by weight or less. The method of claim 9, wherein step (2) is performed at any one temperature in the range of 90°C to 155°C. The method of manufacturing an electrode according to claim 9, wherein step (2) is performed so that the amount of residual solvent is 5% by weight or less when the amount of the solvent in the slurry before (1) preheating treatment is 100% by weight. 10. The method of claim 9, further comprising the step of (3) evaporating the reduction rate on the current collector having the slurry layer formed thereon following step (2). 14. The method of claim 13, further comprising (4) removing residual solvent following step (3). The method for manufacturing an electrode according to claim 8, wherein the active layer precursor is rolled with an impregnating parameter (f) of 0.03 or less specified by Equation 1 .

Images