KR102814169B1 - Method for measuring wet adhesive strength of insulation layer using ultrasonic waves and system measuring wet adhesive strength of insulation layer - Google Patents

Abstract

The present invention relates to a method for measuring the wet adhesion of an insulating layer using ultrasonic waves and a system for measuring the wet adhesion of an insulating layer, which have the advantage of easily measuring the wet adhesion reflecting the electrolyte impregnation state of an insulating layer applied during electrode manufacturing.

Description

{METHOD FOR MEASURING WET ADHESIVE STRENGTH OF INSULATION LAYER USING ULTRASONIC WAVES AND SYSTEM MEASURING WET ADHESIVE STRENGTH OF INSULATION LAYER}

The present invention relates to a method for measuring the wet adhesion of an insulating layer using ultrasonic waves and a system for measuring the wet adhesion of an insulating layer.

As technological development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, much research is being conducted on batteries that can meet various needs.

In terms of battery shape, there is a high demand for square batteries and pouch-type batteries that can be applied to products such as mobile phones due to their thin thickness, and in terms of materials, there is a high demand for lithium secondary batteries such as lithium cobalt polymer batteries that have excellent energy density, discharge voltage, and safety.

One of the major research tasks in these secondary batteries is to improve safety. The main cause of safety-related accidents in batteries is due to abnormal high temperature conditions caused by short circuits between the positive and negative electrodes. In other words, under normal circumstances, the separator between the positive and negative electrodes is located to maintain electrical insulation, but under abnormal circumstances such as overcharge or overdischarge of the battery, dendritic growth of electrode materials or internal short circuit caused by foreign substances, sharp objects such as nails or screws piercing the battery, or excessive deformation of the battery due to external force, the existing separator shows its limitations.

In general, the separator is mainly a microporous membrane made of polyolefin resin, but its heat resistance is insufficient as its heat resistance temperature is about 120 to 160℃. Therefore, when an internal short circuit occurs, the separator shrinks due to the short circuit reaction heat, the short circuit area expands, and a thermal runaway state occurs in which a larger amount of reaction heat is generated. This phenomenon mainly occurs at the electrode active material-coated end of the electrode current collector coated with the electrode active material when stacking electrodes, and various methods have been attempted to reduce the possibility of a short circuit of the electrode under external impact or at high temperatures.

Specifically, in order to solve the internal short circuit of the battery, a method has been proposed of forming an insulating coating layer by attaching an insulating tape to a part of the non-conductive part and the composite layer of the electrode, or by coating an insulating liquid. For example, a method has been proposed of applying a binder for insulating purposes to a part of the non-conductive part and the composite layer of the positive electrode, or of coating an insulating liquid (hereinafter, an insulating coating layer) by dispersing a mixture of the binder and inorganic particles in a solvent.

Meanwhile, in the electrode manufacturing process of a secondary battery, since mechanical/environmental loads are applied to the electrode, metal specimens are sampled after a certain stage or by section, and their physical properties are required to be evaluated. Among the physical properties of the electrode, the adhesive strength of the insulating layer is a major factor affecting the stability of the secondary battery, so a process of measuring the adhesive strength of the insulating layer on the electrode current collector is required during the manufacturing process. Specifically, the method of measuring the adhesive strength of the insulating layer is to peel the insulating layer from the metal specimen and measure the peel strength.

As described above, a conventional method for measuring the adhesion of an insulating layer measures the peel strength of the insulating layer in a dried state.

However, the electrodes in an actual secondary battery exist in a state of being immersed in an electrolyte. Therefore, in order to evaluate the stability of a secondary battery more accurately, a technology is needed that can measure the wet adhesion that reflects the electrolyte immersion state of the insulating layer applied during electrode manufacturing.

Chinese Publication Patent No. 111157446

The present invention is intended to solve the above problems, and aims to provide a method for measuring the wet adhesive strength of an insulating layer using ultrasonic waves and a system for measuring the wet adhesive strength of an insulating layer.

In order to solve the above-described problem, the present invention provides a method for measuring wet adhesion of an insulating layer, including, in one example, the steps of: wetting a metal specimen having an insulating layer formed thereon in an electrolyte; applying ultrasonic waves to the electrolyte in which the metal specimen is impregnated; and checking the adhesion of the insulating layer formed on the metal specimen.

In a specific example, the step of checking the adhesion of the insulating layer formed on the metal specimen includes a process of checking whether the insulating layer is swelling or detached.

In another example, the step of checking the adhesion of the insulating layer of the metal specimen may include a process of measuring the adhesion of the insulating layer by applying a tensile force to one side of the insulating layer while fixing the metal specimen impregnated with the electrolyte and measuring the force at which the insulating layer is peeled off from the metal specimen.

At this time, the method for measuring the wet adhesion of an insulating layer according to the present invention may further include a step of forming a self-standing region of the insulating layer before the step of impregnating the metal specimen with an electrolyte. In a specific example, the step of forming the self-standing region of the insulating layer may include a process of peeling off one end of the insulating layer so that one side of the insulating layer becomes self-standing in a direction perpendicular to the metal specimen.

The step of impregnating the metal specimen with the electrolyte may include a process of impregnating the metal specimen, excluding the self-standing region of the insulating layer, with the electrolyte.

In addition, the step of measuring the adhesion of the insulating layer may include a process of attaching one side of a metal specimen on which the insulating layer is not formed to a test substrate.

Additionally, the step of measuring the adhesion of the insulating layer may include a process of pulling one side of the insulating layer in a direction perpendicular to the test substrate.

Meanwhile, the step of applying ultrasonic waves to the electrolyte can be performed by a tip sonicator or a bath sonicator.

At this time, the step of applying ultrasonic waves to the electrolyte may include a process of applying ultrasonic waves of 1 kHz to 200 kHz for 1 to 10 minutes.

At this time, the electrolyte may include at least one organic solvent selected from the group consisting of ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, propylene carbonate (PC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinylethylene carbonate (VEC), butylene carbonate, ethyl propionate, ethyl butyrate, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, gamma-valerolactone, ma-butyrolactone, and tetrahydrofuran.

Additionally, the metal specimen may be aluminum, copper or an aluminum alloy, and the insulating layer may include a binder polymer; or inorganic particles and a binder polymer.

In addition, the present invention provides a system for measuring wet adhesion of an insulating layer, including, in one example, a tank containing an electrolyte therein and impregnated with a metal specimen having an insulating layer formed thereon; an ultrasonic disperser applying ultrasonic waves to the electrolyte impregnated with the metal specimen; and a test substrate to which the metal specimen impregnated with the electrolyte is attached.

At this time, the ultrasonic disperser can be a tip sonicator or a bath sonicator.

In another example, the wet adhesion measurement system of the insulating layer includes a test substrate to which a metal specimen immersed in an electrolyte is attached; a fixing jig for fixing the test substrate to which the metal specimen is attached; and an adhesion measurement device including a gripping portion for holding one side of the insulating layer, and applying a tensile force to the held insulating layer to measure a force for peeling the insulating layer from the metal specimen.

In addition, the fixing jig may include a fixing portion on which a test substrate is fixed; and first and second fixing portions in the form of bars installed on the fixing portion to fix one side and the other side of the test substrate, respectively; and one side of the second fixing portion may be a structure in which it is rotatably connected by a hinge pin.

Additionally, the adhesion measuring device may be a 90° peel tester.

The method for measuring wet adhesion of an insulating layer using ultrasonic waves according to the present invention and the system for measuring wet adhesion of an insulating layer can reflect the electrolyte impregnation state of an insulating layer applied during electrode manufacturing, and have the advantage of being able to measure the wet adhesion of an insulating layer more accurately and easily.

Figure 1 is a flow chart showing a method for measuring wet adhesion of an insulating layer according to one embodiment of the present invention.
Figure 2 is a schematic diagram of a system for measuring wet adhesion of an insulating layer according to the present invention.
Figure 3 is a schematic diagram of a fixing jig of a wet adhesion measurement system of an insulating layer.
Figure 4 is a drawing showing the results of measuring the wet adhesion of the insulating coating layers of examples and comparative examples.
Figure 5 is a photograph showing the process of measuring the wet adhesion of a metal specimen on which an insulating layer has been formed sequentially.

The present invention is susceptible to various modifications and various embodiments, and specific embodiments will be described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

In the present invention, it should be understood that terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

In addition, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only the case where it is "directly below" the other part, but also the case where there is another part in between. Furthermore, in the present application, being disposed "on" may include the case where it is disposed below as well as above.

In the present invention, the "insulating layer" may be an insulating coating layer formed by applying and drying an insulating liquid (slurry for an insulating layer) to an electrode tab portion of an electrode current collector coated with an electrode active material. That is, in the present invention, the insulating layer means a measured object to be measured in the method for measuring wet adhesion of an insulating layer of the present invention. Specifically, the insulating layer may be a binder polymer; or an insulating liquid including inorganic particles and a binder polymer.

In the present invention, "wet adhesion" means the adhesion of an insulating coating layer measured in a state immersed in an electrolyte. More specifically, the wet adhesion can be measured by immersing a metal specimen having an insulating coating layer formed thereon in an electrolyte, applying ultrasonic waves, and then checking whether the insulating coating layer swells or peels off. Alternatively, the wet adhesion can mean the adhesion measured through a 90° peel test after immersing a metal specimen having an insulating coating layer formed on one surface in an electrolyte. In particular, the wet adhesion can reflect the electrolyte impregnation state of an insulating coating layer applied during electrode manufacturing in order to evaluate the safety of a secondary battery.

In the present invention, the term "metal specimen" refers to a space where an insulating coating layer is formed, and may mean a metal collector used in the manufacture of an electrode, and may be a metal collector punched to have a predetermined width and a predetermined length. For example, the metal specimen may be aluminum, copper, or an aluminum alloy.

In the present invention, the "overlay region" may mean a region in which an insulating coating layer is formed on an electrode. More specifically, the insulating coating layer covers from at least a part of a non-coated portion of an electrode in which a composite layer is formed to at least a part of the composite layer, and the region in which the insulating coating layer is formed on the composite layer may be referred to as an overlay region.

Hereinafter, the present invention will be described in more detail.

[First embodiment]

The present invention provides a method for measuring wet adhesion of an insulating layer as a first embodiment.

Insulating layer Method for measuring wet adhesion

In one embodiment of the present invention,

A step of wetting a metal specimen on which an insulating layer has been formed in an electrolyte;

A step of applying ultrasonic waves to an electrolyte solution in which a metal specimen is impregnated; and

A method for measuring wet adhesion of an insulating layer is provided, including a step of checking the adhesion of an insulating layer formed on a metal specimen.

FIG. 1 is a flow chart of a method for measuring wet adhesion of an insulating layer according to the present invention. Referring to FIG. 1, a method for measuring wet adhesion of an insulating layer according to the present invention may include a step (S10) of wetting a metal specimen on which an insulating layer is formed in an electrolyte; a step (S20) of applying ultrasonic waves to the electrolyte in which the metal specimen is impregnated; and a step (S30) of checking the adhesion of an insulating layer formed on the metal specimen.

In general, among the physical property evaluations of electrodes, the evaluation of the adhesive strength of the insulating layer is a major factor affecting the performance or stability of secondary batteries, and therefore, a process of measuring the adhesive strength of the insulating layer is required during the electrode manufacturing process. In order to measure the adhesive strength of the insulating layer, the insulating layer is peeled off from a metal specimen coated with the insulating layer, and the peeling strength is measured. Specifically, double-sided tape is attached to a slide glass, and the metal specimen to be evaluated is attached to one side of the slide glass so that the insulating layer of the metal specimen is in contact with the surface of the slide glass. Then, the force of peeling from the slide glass was measured by pulling one side of the metal specimen using a UTM device. That is, a conventional method of measuring the adhesive strength of an insulating layer measures the peeling strength of the insulating layer in a dried state.

However, the electrodes in an actual secondary battery exist in a state of being immersed in an electrolyte. Therefore, in order to evaluate the stability of a secondary battery more accurately, a technology is needed that can measure the wet adhesion that reflects the electrolyte immersion state of the insulating layer applied during electrode manufacturing.

The method for measuring wet adhesion of an insulating layer according to the present invention is described in detail as follows.

Metal specimens in electrolyte Wetting Step (S10)

The method for measuring the wet adhesion of an insulating layer according to the present invention includes a step of immersing a metal specimen having an insulating layer formed on one surface into an electrolyte. In a specific example, the step of immersing the metal specimen into the electrolyte is for simulating an electrode state within a secondary battery, and more specifically, for simulating a metal current collector having an insulating layer formed within a secondary battery. By immersing the metal specimen having the insulating layer formed thereon into an electrolyte and then measuring its adhesion, the performance or safety of the secondary battery can be more easily evaluated.

In addition, in the step of impregnating the metal specimen into the electrolyte, the electrolyte can be controlled in a temperature range of 10°C to 150°C, and specifically, can be controlled in a temperature range of 15°C to 140°C; 25°C to 130°C; and 30°C to 120°C. The present invention controls the temperature of the electrolyte in the above temperature range, and can evaluate the adhesive strength of the insulating layer in the above temperature range.

Meanwhile, the method for measuring the wet adhesion of an insulating layer according to the present invention may further include a step of preparing a metal specimen on which an insulating layer is formed by coating an insulating liquid on the metal specimen. In a specific example, the insulating layer may be formed by applying and drying an insulating liquid (slurry for an insulating layer) on one surface of the metal specimen.

This insulating layer may be a commonly used insulating liquid (slurry for an insulating layer), may be a binder polymer, or may include inorganic particles and a binder polymer, and may further include a dispersant as needed. In a specific example, the insulating layer may include the inorganic particles and the binder polymer in a weight ratio of 1:99 to 95:5, specifically, may include the inorganic particles and the binder polymer in a weight ratio of 5:95 to 90:10, 5:95 to 80:20, or 10:90 to 50:50.

The above inorganic particles may be at least one selected from the group consisting of alumina (Al ₂ O ₃ ), boehmite (AlOOH), silica (SiO ₂ ), titanium dioxide (TiO ₂ ), aluminum hydroxide (Al(OH) ₃ ), magnesium oxide (MgO), magnesium hydroxide (Mg(OH) ₂ ), zinc oxide (ZnO), barium titanate (BaTiO), aluminum nitride (AlN), boron nitride (BN), silicon carbide (SiC), and beryllium oxide (BeO).

In addition, the binder polymer may be at least one selected from the group consisting of polyvinylidene fluoride, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, acrylic rubber, butyl rubber, fluoroelastomer, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene copolymer, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, and diacetyl cellulose.

Examples of the dispersant include cellulose compounds, and non-limiting examples thereof include carboxyl methyl cellulose, carboxyl ethyl cellulose or derivatives, for example, cation-substituted compounds such as ammonium ion and divalent metal ion thereof. The dispersant can be used in an amount of 0.1 to 5 wt% relative to the inorganic particles. Meanwhile, solvents or dispersion media used in the slurry for forming the insulating layer include water; alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone and kenyl ethyl ketone; ethers such as methyl ethyl ether, diethyl ether, and diisoamyl ether; lactones such as gamma-butyrolactone; N-methyl-2-pyrrolidone (NMP); lactams such as beta-lactam; cyclic aliphatics such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene and toluene; Esters such as methyl lactate and ethyl lactate can be used. Among these, water can be particularly suitably used as an environmentally friendly dispersion medium.

Methods for forming an insulating layer on a metal specimen include, but are not limited to, dipping, spray coating, spin coating, roll coating, die coating, gravure printing, and bar coating.

Meanwhile, in the method for measuring the wet adhesion of an insulating layer according to the present invention, the metal specimen may be aluminum, copper or an aluminum alloy. For example, the metal specimen may be aluminum.

Furthermore, the electrolyte used in the electrolyte impregnation step may be an organic solvent. In a specific example, the organic solvent may be, without limitation, those commonly used in electrolytes for lithium secondary batteries, and may include at least one organic solvent selected from the group consisting of ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, propylene carbonate (PC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinylethylene carbonate (VEC), butylene carbonate, ethyl propionate, ethyl butyrate, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, gamma-valerolactone, ma-butyrolactone, and tetrahydrofuran.

In particular, among the above carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents with high dielectric constants and thus can better dissociate lithium salts in the electrolyte. When low-viscosity, low-dielectric constant linear carbonates, such as dimethyl carbonate and diethyl carbonate, are mixed and used in an appropriate ratio with these cyclic carbonates, an electrolyte having higher electrical conductivity can be produced.

Meanwhile, since the electrolyte does not contain lithium salts, etc., it is possible to prevent the pH of the electrolyte from decreasing due to continuous reaction between the lithium salt and moisture in the air. Accordingly, it is possible to prevent the physical properties of the electrolyte from changing.

Metal specimen Impregnated Step of applying ultrasonic waves to the electrolyte (S20)

A method for measuring wet adhesion of an insulating layer according to the present invention includes a step of applying ultrasonic waves to an electrolyte solution in which a metal specimen is impregnated.

The method for measuring the wet adhesion of an insulating layer according to the present invention can measure the wet adhesion of an insulating layer more accurately by applying ultrasonic waves to an electrolyte in which the metal specimen is impregnated.

The step of applying ultrasonic waves to the electrolyte solution in which the metal specimen is impregnated can be performed by a tip sonicator or a bath sonicator, and can be performed by, for example, a tip sonicator.

Meanwhile, the step of applying ultrasonic waves to the electrolyte includes a process of applying ultrasonic waves of 10 Hz to 200 Hz. In a specific example, the step of applying ultrasonic waves to the electrolyte may apply ultrasonic waves having a frequency in the range of 1 kHz to 200 kHz; 5 kHz to 150 kHz; 10 kHz to 100 kHz; 20 kHz to 70 kHz; or 20 kHz to 40 kHz. If the frequency range of the ultrasonic waves is lower than the lower limit, the cavitation effect due to the application of ultrasonic waves may be minimal, and conversely, if the frequency range of the ultrasonic waves exceeds the upper limit, the insulating layer or the metal specimen may be destroyed due to excessive application of ultrasonic waves.

In addition, the step of applying ultrasonic waves to the electrolyte may apply ultrasonic waves within the above range for 1 minute or more. For example, ultrasonic waves may be applied until swelling or detachment of the insulating layer occurs. Meanwhile, the electrolyte may evaporate due to an increase in the temperature of the electrolyte when applying ultrasonic waves, and the application of ultrasonic waves may be stopped.

In a specific example, the step of applying ultrasonic waves to the electrolyte may apply ultrasonic waves to the electrolyte at 20 kHz using a tip sonicator, and amplification control may be possible at the ultrasonic frequency.

formed on a metal specimen Insulating layer Step for checking adhesion (S30)

The method for measuring wet adhesion of an insulating layer according to the present invention may include a step of checking the adhesion of an insulating layer impregnated with an electrolyte. In a specific example, the step of checking the adhesion of an insulating layer formed on a metal specimen may include a process of checking whether the insulating layer is swelling or detached.

By immersing the metal specimen on which the insulating layer is formed in an electrolyte and applying ultrasonic waves, swelling and detachment of the insulating layer formed on the metal specimen can be checked to determine whether the wet adhesive strength of the insulating layer is excellent.

For example, when a metal specimen having an insulating layer formed thereon is immersed in an electrolyte and ultrasonic waves are applied, if no swelling or detachment occurs in the insulating layer, it can be judged that the adhesive strength is excellent.

[Second embodiment]

The present invention provides a method for measuring wet adhesion of an insulating layer as a second embodiment.

Insulating layer Method for measuring wet adhesion

In one embodiment of the present invention,

A step of wetting a metal specimen on which an insulating layer has been formed in an electrolyte;

A step of applying ultrasonic waves to an electrolyte solution in which a metal specimen is impregnated; and

A method for measuring wet adhesion of an insulating layer is provided, including a step of checking the adhesion of an insulating layer formed on a metal specimen.

Metal specimens in electrolyte Wetting Step (S10)

The method for measuring the wet adhesion of an insulating layer according to the present invention includes a step of immersing a metal specimen having an insulating layer formed on one surface into an electrolyte. In a specific example, the step of immersing the metal specimen into the electrolyte is for simulating an electrode state within a secondary battery, and more specifically, for simulating a metal current collector having an insulating layer formed within a secondary battery. By immersing the metal specimen having the insulating layer formed thereon into an electrolyte and then measuring its adhesion, the performance or safety of the secondary battery can be more easily evaluated.

Meanwhile, the method for measuring wet adhesion of an insulating layer according to the present invention may further include a step of forming a self-standing region of the insulating layer prior to the step of impregnating the metal specimen with an electrolyte.

In a specific example, the step of forming the self-standing region of the insulating layer includes peeling one end of the insulating layer coated on the metal specimen from the metal specimen, and allowing the region peeled from the metal specimen to be self-standing in a vertical direction from the metal specimen. The self-standing region of the insulating layer is a region gripped by a grip portion of an adhesion measuring device, which will be described later, and is a region of the insulating layer that is not impregnated with an electrolyte. More specifically, the self-standing region may have a shape in which the other end is connected to the metal-coated insulating layer, and one end is self-standing in a vertical direction from the metal specimen.

The self-standing region of the above-mentioned insulating layer is connected to the grip portion of the adhesive strength measuring device in the adhesive strength measuring step, and can receive a pulling force in a direction perpendicular to the metal specimen. At this time, the self-standing region is not affected by the electrolyte, so that the insulating layer can be prevented from tearing when measuring the adhesive strength of the insulating layer, and the adhesive strength of the insulating layer attached to the metal specimen can be easily measured.

Next, the method for measuring the wet adhesion of an insulating layer according to the present invention includes a step of immersing a metal specimen having the insulating layer formed thereon in an electrolyte. In a specific example, the metal specimen may be immersed in the electrolyte by placing the metal specimen in a tank or tray having a space formed therein and then pouring the electrolyte therein.

Meanwhile, the step of impregnating the metal specimen with the electrolyte may include a process of impregnating the metal specimen with the electrolyte except for the self-standing region of the insulating layer. The self-standing region of the insulating layer is a region that is gripped by the grip part of the adhesive force measuring device, and the self-standing region is not impregnated with the electrolyte to prevent it from being affected by the electrolyte.

In addition, in the step of impregnating the metal specimen into the electrolyte, the electrolyte is at 10°C. The temperature of the electrolyte can be controlled in a temperature range of from 10 to 150°C, and specifically, it can be controlled in a temperature range of from 15°C to 140°C; from 25°C to 130°C; and from 30°C to 120°C. The present invention controls the temperature of the electrolyte in the above temperature range, and can evaluate the adhesive strength of the insulating layer in the above temperature range.

Metal specimen Impregnated Step of applying ultrasonic waves to the electrolyte (S20)

A method for measuring wet adhesion of an insulating layer according to the present invention includes a step of applying ultrasonic waves to an electrolyte solution in which a metal specimen is impregnated.

The method for measuring the wet adhesion of an insulating layer according to the present invention applies ultrasonic waves to an electrolyte in which the metal specimen is impregnated, so that the wet adhesion of the insulating layer can be measured more accurately, and the swelling phenomenon occurring within a secondary battery can be provided, so that the impregnation state of the electrolyte in the metal specimen on which the insulating layer is formed can be reflected. Since this has been described above, a detailed description thereof will be omitted.

formed on a metal specimen Insulating layer Step for checking adhesion (S30)

The method for measuring wet adhesion of an insulating layer according to the present invention includes a step of measuring the adhesion of an insulating layer by applying a tensile force to one side of the insulating layer while fixing a metal specimen impregnated with an electrolyte and measuring the force at which the insulating layer is peeled off from the metal specimen.

In a specific example, the step of measuring the adhesive strength of the insulating layer includes a process of attaching a metal specimen on which an insulating layer is formed to a test substrate. At this time, the metal specimen can be attached to the test substrate in an area where the insulating layer is not formed. The test substrate is for attaching and fixing the metal specimen, and may be a metal block or a glass substrate (Slide glass), for example, a glass substrate.

In addition, in the above process, the metal specimen can be attached to the test substrate using an adhesive such as an epoxy adhesive or a double-sided tape. For example, the metal specimen can be attached to the test substrate using a polyimide double-sided tape. Meanwhile, in the method for measuring wet adhesion of an insulating layer according to the present invention, the metal specimen can be attached to the test substrate before the step of immersing the metal specimen in the electrolyte; however, if the adhesive member is exposed to the electrolyte, the adhesive member may be deformed or the adhesive strength may be weakened. Therefore, it is preferable to attach the metal specimen to the test substrate after immersing the metal specimen in the electrolyte.

Furthermore, the step of measuring the adhesive strength of the insulating layer includes a process of pulling the self-standing region of the insulating layer in a direction perpendicular to the test substrate. That is, the step of measuring the adhesive strength of the insulating layer can be measured by a 90° peel test method. For example, after setting the load of the UTM device to zero, the adhesive strength of the metal specimen can be measured by setting the load speed in the range of 10 to 200 mm/min. For example, the adhesive strength of the insulating layer formed on the metal specimen can be measured using a UTM (TA Company) device.

The step (S30) of measuring the adhesive strength of the insulating layer is to measure the adhesive strength of the insulating layer in a wet state, which allows for easy measurement of the adhesive strength of the insulating layer in a state simulating an electrode inside a secondary battery.

[Third embodiment]

The present invention provides a system for measuring wet adhesion of an insulating layer as a third embodiment.

Insulating layer Wet Adhesion Measurement System

The present invention provides a wet adhesion measurement system of an insulating layer for the wet adhesion measurement method of an insulating layer described above.

In one example, a system for measuring wet adhesion of an insulating layer according to the present invention may include a tank containing an electrolyte therein and impregnated with a metal specimen having an insulating layer formed thereon; and an ultrasonic disperser that applies ultrasonic waves to the electrolyte in which the metal specimen is impregnated.

The above tank (not shown) is configured to contain an electrolyte inside and is used to immerse a metal specimen having an insulating layer formed thereon into the electrolyte. A recessed structure that allows the electrolyte to be contained inside is preferable.

In particular, the wet adhesion measurement system according to the present invention may include an ultrasonic disperser (not shown) that applies ultrasonic waves to the electrolyte. In a specific example, the ultrasonic disperser is for applying ultrasonic waves to the electrolyte in which the metal specimen is impregnated. That is, after applying ultrasonic waves to the electrolyte in which the metal specimen is impregnated, the purpose is to check whether the insulating layer formed on the metal specimen is swollen and detached to confirm whether the wet adhesion of the insulating layer is excellent. Accordingly, the wet adhesion of the insulating layer (111) can be measured more accurately.

The above ultrasonic disperser may be a tip sonicator or a bath sonicator, and may be performed by, for example, a tip sonicator.

The method includes applying ultrasonic waves of 1 kHz to 200 kHz to the electrolyte using the ultrasonic disperser. In a specific example, the step of applying ultrasonic waves to the electrolyte may apply ultrasonic waves having a frequency in the range of 1 kHz to 200 kHz; 5 kHz to 150 kHz; 10 kHz to 100 kHz; 20 kHz to 70 kHz; or 20 kHz to 40 kHz. If the frequency range of the ultrasonic waves is lower than the lower limit, the cavitation effect due to the application of ultrasonic waves may be minimal, and conversely, if the frequency range of the ultrasonic waves exceeds the upper limit, the insulating layer or metal specimen may be destroyed due to excessive application of ultrasonic waves.

In addition, the step of applying ultrasonic waves to the electrolyte may apply ultrasonic waves within the above range for 1 minute or more. For example, ultrasonic waves may be applied until swelling or detachment of the insulating layer occurs. Meanwhile, the electrolyte may evaporate due to an increase in the temperature of the electrolyte when applying ultrasonic waves, and the application of ultrasonic waves may be stopped.

FIG. 2 is a schematic diagram of a wet adhesion measurement system of an insulating layer according to the present invention, and FIG. 3 is a schematic diagram of a fixing jig of the wet adhesion measurement system of an insulating layer. Referring to FIGS. 2 and 3, a wet adhesion measurement system (100) of an insulating layer according to the present invention includes: a tank (not shown) containing an electrolyte therein and impregnating a metal specimen (112) having an insulating layer formed on one surface; an ultrasonic disperser (not shown) that applies ultrasonic waves to the electrolyte impregnated with the metal specimen (112); a test substrate (110) to which the metal specimen (112) impregnated with the electrolyte is attached; a fixing jig (120) that fixes the test substrate (110) to which the metal specimen (112) is attached; It includes a grip portion (131) that holds one side of the insulating layer, and an adhesive force measuring device (130) that applies a tensile force to the held insulating layer (111) and measures the force at which the insulating layer (111) is peeled off from the metal specimen (112).

In one example, the test substrate (110) of the wet adhesion measurement system (100) of the insulating layer according to the present invention is for fixing a metal specimen (112) on which an insulating layer (111) is formed, and may be a metal block or a glass substrate (slide glass), for example, a glass substrate. The metal specimen (112) on which the insulating layer (111) is formed may be in a state of being impregnated with an electrolyte.

Meanwhile, the metal specimen (112) may be attached to the surface of the test substrate (110) using an adhesive member (not shown). In a specific example, the surface of the test substrate (110) may be attached to the opposite side of the metal specimen (112) where the insulating layer (111) is not formed. In addition, the insulating layer (111) of the metal specimen (112) attached to the test substrate (110) may have a structure in which a self-standing region is formed. In a specific example, one end of the insulating layer (111) coated on the metal specimen (112) is peeled off from the metal specimen (112), and the region peeled off from the metal specimen (112) is made to be self-standing in the vertical direction from the metal specimen (112). The self-standing region of the insulating layer (111) is a region that is gripped by the grip portion (131) of the adhesive force measuring device (130) described below, and is a region of the insulating layer (111) that is not impregnated with an electrolyte. More specifically, the self-standing region (1111) may have a shape in which one end is connected from a metal-coated insulating layer (111) and the other end is vertically independent from a metal specimen. The self-standing region (1111) of the insulating layer (111) may be connected to a grip portion (131) of an adhesive force measuring device (130) and may receive a pulling force in a direction perpendicular to the test substrate (110).

The adhesive member may be a strong adhesive having a high adhesive strength and not deforming during the adhesive strength measurement so as not to affect the metal specimen (112). The adhesive member may be an epoxy adhesive or a double-sided tape, for example, a polyimide double-sided tape.

In one example, a wet adhesion measurement system (100) of an insulating layer (111) according to the present invention includes a fixing jig (120) for fixing a test substrate (110). In a specific example, the fixing jig (120) includes a fixing portion (121) on which a test substrate (110) is fixed; and first and second fixing portions (122, 123) in the form of bars installed on the fixing portion (121) and fixing one side and the other side of the test substrate (110), respectively.

The above fixing member (121) is in the form of a plate, and a space for fixing a test substrate (110) can be provided. In addition, the first and second fixing members (122, 123) are in the form of a bar, and the test substrate (110) fixed to the fixing jig (120) is positioned between the upper surface of the fixing member (121) and the fixing members (122, 123). In addition, the first and second fixing members (122, 123) may further include clamping members (1221, 1231), respectively. The clamping members (1221, 1231) serve to fix the test substrate (110) inserted between the fixing member (121) of the fixing jig (120) and the first and second fixing members (122, 123), respectively. For example, the clamping members (1221, 1231) may be clamping bolts. In addition, the first and second fixing members (122, 123) may include holes formed with screw threads having a structure corresponding to the screw threads formed on the outer surface of the clamping bolts, and the clamping bolts may fix the test substrate (110) when fastened to the holes of the first and second fixing members (122, 123).

As illustrated in FIG. 3, the first fixing member (122) is provided in a fixed state inside the fixing member (121) of the fixing jig (120), and may be provided on one side of the space where the test substrate (110) is fixed. As described above, the first fixing member (122) is in the shape of a bar, and the first fixing member (122) in the shape of a bar may have a structure in which both ends are fixed to the upper surface of the fixing jig (120). Meanwhile, the first fixing member (122) may be installed in a direction crossing the length of the test substrate (110), and the central region of the first fixing member (122) may have a structure that is curved upward, except for both ends, so that the test substrate (110) can be positioned between the upper surface of the fixing jig (120) and the first fixing member (122). Furthermore, a clamping member (1221) is installed in the central area of the first fixing member (122), and the clamping member (1221) can fix one side of the test substrate (110).

The second fixing part (123) is arranged on the upper part of the fixing part (121) of the fixing jig (120), and may be provided on the other side of the space where the test substrate (110) is fixed. However, the second fixing part (123) may be in the form of a bar, like the first fixing part (122), but may have a structure in which one side is rotatably fastened by a hinge pin (not shown), and the other side may have a structure in which a fastening groove (1232) is formed. For reference, the fastening groove (1232) may be fastened to a fastening projection, which will be described later. The second fixing part (123) may have one side fixed and the other side rotatably fastened, so that the test substrate (110) may be easily fastened.

In addition, the fixing jig (120) may include a fixing projection (1233) to which the fixing groove (1212) of the second fixing portion (123) is fixed. In a specific example, the fixing projection (1233) may be located in an area facing a hinge pin (not shown). That is, when the fixing groove (1232) of the second fixing portion (123) is fixed to the fixing projection (1233), the first and second fixing portions (122, 123) may have a structure that is parallel to each other.

Meanwhile, the second fixing member (123) may have a structure in which the central region thereof, except for both ends of the second fixing member (123), is curved upwards so that the test board (110) can be positioned between the upper surface of the fixing jig (120) and the second fixing member (123), similar to the first fixing member (122). In addition, a clamping member (1231) may be installed in the central region of the second fixing member (123).

In order to fix a test board (110) having a metal specimen (112) attached to the above-described fixing jig (120), the test board (110) is first placed on the fixing portion (121) of the fixing jig (120). At this time, the other side fixing groove (1212) of the second fixing portion (123) is removed from the fixing projection (1233). Then, the clamping member (1221) of the first fixing portion (122) is pressed to fix one side of the test board (110). Meanwhile, since the present invention measures the wet adhesive strength of the insulating layer (111), the first fixing portion (122) is positioned above the metal specimen (112) so that the metal specimen (112) is not tensioned together when measuring the wet adhesive strength of the insulating layer (111).

Next, the other side of the second fixing member (123) is rotated so that the fastening groove (1212) is fastened to the fastening projection (1233). Then, the clamping member (1231) of the second fixing member (123) is pressed to fasten the other side of the test substrate (110). Meanwhile, when the metal specimen (112) is attached to the test substrate (110), the self-standing area (1111) is excluded, so that the clamping member (1231) of the second fixing member (123) can fix only the test substrate (110) excluding the self-standing area (1111) of the metal specimen (112).

In one example, a wet adhesion measurement system (100) of an insulating layer according to the present invention includes an adhesion measurement device (130). In a specific example, the adhesion measurement device (130) includes a grip portion (131) that grips one area of an insulating layer (111), and can measure a force (hereinafter, adhesion) for peeling the insulating layer (111) from a metal specimen (112) by applying a tensile force to the gripped insulating layer (111).

The above-described adhesive force measuring device (130) may be a typical 90° peel tester. In a specific example, the adhesive force measuring device (130) may measure the adhesive force of a metal specimen (112) by fixing a self-standing area (1111) of the metal specimen (112) to a grip portion (131) of the adhesive force measuring device (130) and measuring the peeling force of the composite layer at a 90° angle (90° peel test).

In one example, the adhesive strength measuring device (130) further includes an output unit (133) that outputs a force for peeling an insulating layer (111) from a metal specimen (112). The output unit (133) can express the adhesive strength of the insulating layer (111) in a numerical value.

In another example, the adhesive strength measuring device (130) may further include a storage unit (not shown). When the wet adhesive strength measurement of the insulating layer (111) is completed, the storage unit receives and stores the wet adhesive strength measurement result. The storage unit may store the measurement result of the insulating layer (111) and create a database thereof. Specifically, the type of binder, inorganic particles, dispersant or solvent included in the insulating layer (111), thickness, temperature during electrolyte impregnation, etc. may be divided into types, and the adhesive strength measurement result of the insulating layer (111) may be organized in a table or graph accordingly. When such measurement data are combined in various ways, the adhesive strength of the insulating layer (111) can be predicted, and whether the insulating layer is detached after manufacturing a battery cell can be predicted.

In another example, the tank may include a temperature control unit (not shown) that controls the temperature of the electrolyte contained therein. In a specific example, the temperature control unit may control the temperature of the electrolyte in a temperature range of 10° C. to 150° C. when the metal specimen (112) on which the insulating layer (111) is formed is immersed in the electrolyte, and specifically, may control the temperature in a temperature range of 15° C. to 140° C.; 25° C. to 130° C.; and 30° C. to 120° C. The present invention controls the temperature of the electrolyte in the temperature range and evaluates the adhesive strength of the insulating layer in the temperature range.

The above temperature control unit may be a commonly used heating member and/or cooling member, and the tray may further include a temperature sensor for measuring the temperature of the electrolyte contained therein in real time. This is to easily simulate the electrode state inside the secondary battery and to evaluate the adhesive strength of the insulating layer (111) according to the temperature of the electrolyte.

In one example, the adhesion measuring device (130) includes a grip portion (131) for gripping a self-standing area (1111), which is one area of the insulating layer (111).

At this time, the grip portion (131) may include a metal jaw face (1311) having a grid formed on the surface, or may include an elastic pad. In general, during the process of measuring the wet adhesive force of the insulating layer (111), a phenomenon in which the insulating layer (111) breaks or slips may occur while being pressed by the grip portion (131). In the present invention, by including a grid or an elastic pad on the jaw face surface facing the insulating layer (111), the fixing force of the grip portion (131) to the insulating layer (111) can be increased. The jaw face (1311) can be formed of various types of metal, and may be made of, for example, carbon steel, stainless steel, aluminum, or an alloy thereof. The 'grid' mentioned in the present invention means a pattern in the shape of a grid or a checkerboard grid, and collectively refers to a form in which two or more parallel patterns intersect each other.

Hereinafter, the present invention will be described in more detail through examples and the like. However, the configurations described in the examples described in this specification are only one embodiment of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

Example 1.

A dispersant (carboxymethyl cellulose) was dissolved in N-methyl-2-pyrrolidone (NMP) as a solvent, and boehmite (hereinafter, AlOOH) as an inorganic particle was dispersed. A binder was added to the thus dispersed AlOOH slurry so that the inorganic particles and the binder had a weight ratio of 50:50, thereby obtaining an insulating coating layer composition. At this time, styrene-butadiene rubber (hereinafter, SBR) was used as the binder.

Example 2~4, Comparative example 1~2.

An insulating coating solution was obtained in the same manner as in Example 1, except that the content of inorganic particles and binder was changed when preparing the insulating coating layer composition.

The specific compositions of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 1 below.

Insulating coating layer composition menstruum Weapon particles bookbinder Weapon Particle:Binder (Weight Ratio) Example 1 NMP AlOOH SBR 50:50 Example 2 NMP AlOOH SBR 60:40 Example 3 NMP AlOOH SBR 75:25 Example 4 NMP AlOOH SBR 80:20 Comparative Example 1 NMP AlOOH PVDF 80:20 Comparative Example 2 NMP AlOOH PVDF 88:12

Experimental example 1. Insulating layer Wet Adhesion Measurement

In order to evaluate the adhesive strength of the insulating layer according to the present invention, the following experiment was conducted.

Metal specimen with an insulating coating layer formed

The insulating layer compositions manufactured in Examples 1-4 and Comparative Examples 1 and 2 were coated on aluminum metal foil and dried to prepare a metal specimen having an insulating layer of about 10 ㎛ in thickness. The metal specimen having the insulating coating layer formed thereon was punched into a size of 2 cm × 2 cm using a puncher for measuring adhesion.

Ultrasonic authentication

200 g of electrolyte EC/EMC=3/7(vol.%) was added to a 250 ml beaker, and a metal specimen having an insulating layer formed thereon was immersed in the electrolyte. In order to control the movement of the metal specimen, the metal specimen was fixed with a jig.

Then, ultrasonic waves were applied to the electrolyte solution in which the metal specimen was impregnated using an ultrasonic disperser (BANDELIN, 4200). At this time, the ultrasonic wave application conditions were as follows.

- Frequency: 20kHz

- Tip diameter: 13 mm (TS-113)

- Amplitude: 100%

(When using 13 mm tip, peak-to-peak 132 ㎛)

And, the results are shown in Table 2 and Figure 4 below.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 furtherance AlOOH:SBR
=50:50 AlOOH:SBR
=60:40 AlOOH:SBR
=75:25 AlOOH:SBR
=80:20 AlOOH:PVDF
=80:20 AlOOH:PVDF
=88:12 Time (minutes) 19 19 19 15 5 10 End temperature (℃) 109 109 109 100 71 87 Wet Adhesion Comparison No swelling and no tearing No swelling and no tali No swelling and no tali No swelling and no tali Swelling occurs Swelling and tearing occur

Figure 4 is a drawing showing the results of measuring the wet adhesion of the insulating coating layers of Examples 1 and 4 and Comparative Example 1-2.

Looking at Table 2 and Fig. 4, the electrode specimen of Example 1 did not experience swelling or detachment in the insulating coating layer. However, in the case of Example 1, the boiling point of EMC was 107.5°C due to the increase in temperature of the electrolyte caused by the application of ultrasonic waves, and the measurement was stopped when it reached 109°C due to the evaporation of the solvent and the change in the measurement environment.

In addition, for Examples 2 and 3, although not shown in the photographs, no swelling or detachment occurred in the insulating coating layer of the electrode specimens, as in Example 1. However, since the boiling point of EMC was 107.5°C, the measurement environment changed as the solvent evaporated, and the measurement was stopped when it reached 109°C.

In the case of Example 4, when ultrasonic waves were applied to the electrolyte, no swelling or detachment occurred in the electrode specimen for 15 minutes. However, although not disclosed in the drawing, when the temperature of the electrolyte reached 108°C due to the continued application of ultrasonic waves, swelling and detachment of the electrode specimen occurred.

In addition, in the case of Comparative Examples 1 and 2, swelling and detachment occurred in the electrode specimen within 5 minutes of applying ultrasonic waves to the electrolyte.

Through this, the wet adhesion of the insulating layer could be easily measured, and it could be confirmed that the insulating coating layer of the example had superior wet adhesion compared to the insulating coating layer of Comparative Example 1-2.

Experimental example 2. Measurement of wet adhesion of insulating coating layer

The metal specimens manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 were punched into a size of 20 mm × 125 mm, and then the dry adhesion, wet adhesion, etc. were measured. After manufacturing a monocell, the detachment of the insulating layer was checked.

Insulating layer Dry adhesion measurement

The adhesive strength of the metal specimen with the insulating layer formed was measured using the 90° Peel Test method. Specifically, an imide double-sided tape was attached to a slide glass, an electrode specimen was attached thereon, and then a 2 kg roller was used to roll it back and forth 10 times to adhere it. At this time, one side of the metal specimen without the insulating layer formed was attached to the slide glass.

Then, using a UTM (TA Corporation) device, one side of the insulating layer was pulled at 100 mm/min to measure the force required to peel off the slide glass. At this time, the measurement angle between the slide glass and the electrode was 90°.

At this time, three metal specimens were prepared, and the adhesive strength of each insulating layer was measured through the 90° peel test described above, and the average value was calculated, and the results are shown in Table 1 below.

Insulating layer Wet Adhesion Measurement

The adhesion of the metal specimen with the insulating layer formed was measured using the 90° peel test method. Figure 4 is a photograph showing the process of measuring the wet adhesion of the metal specimen with the insulating layer formed sequentially.

Referring to Fig. 4, in a metal specimen having an insulating layer formed thereon, one end of the insulating layer is peeled off from the metal specimen to form a self-standing region of the insulating layer (Fig. 4a). Then, the metal specimen having the insulating layer formed thereon was immersed in a mixed solvent of dimethyl carbonate (DEC) and ethylene carbonate (EC) (DEC:EC=1:1). At this time, the solvent was at an average temperature of 25°C (room temperature), and the electrode specimen was immersed for 1 hour. The self-standing region of the insulating layer was not allowed to be immersed in an electrolyte (Fig. 4b).

Next, imide double-sided tape was attached to a slide glass, and an electrode specimen impregnated with electrolyte was attached thereon, and then a 2 kg roller was used to roll the specimen back and forth 10 times to adhere it. At this time, one side of the metal specimen on which an insulating layer was not formed was attached to the slide glass.

Then, the test board with the electrode specimen attached was fixed to a fixing jig, and the self-standing area of the insulating layer was pulled at 100 mm/min using a UTM (TA Corporation) device to measure the force for the insulating layer to be peeled off from the electrode specimen. At this time, the measurement angle between the slide glass and the insulating layer was 90° (Figs. 4c and 4d).

For reference, three metal specimens under the same conditions were prepared, and the adhesive strength of each insulating layer was measured through the aforementioned 90° peel test, and the average value was calculated, and the results are shown in Table 1 below.

Using ultrasound Insulating layer Wet Adhesion Measurement

The wet adhesion of the insulating layer was measured using the same method as that described above, except that ultrasonic waves were applied during electrolyte impregnation.

Specifically, the metal specimen on which the insulating layer was formed was immersed in a mixed solvent of dimethyl carbonate (DEC) and ethylene carbonate (EC) (DEC:EC=1:1). Then, ultrasonic waves were applied to the electrolyte in which the metal specimen was immersed for 5 minutes using a tip sonicator.

Then, the adhesive strength of each insulation layer was measured through the aforementioned 90° peel test, the average value was calculated, and the results are shown in Table 1 below.

After manufacturing the battery cell Insulating layer Tally Check whether

After manufacturing the monocell, we checked whether the insulation layer detached.

The monocell was manufactured by using lithium metal as an anode, interposing a separator between each cathode and anode, and laminating the electrode assembly. Meanwhile, an insulating solution used in the example was applied to the electrode tab portion of the cathode to form an insulating layer. Thereafter, the electrolyte was manufactured by dissolving 1 M LiPF ₆ in a mixed solvent of dimethyl carbonate (DEC) and ethylene carbonate (EC) (DEC:EC = 1:1).

The lithium secondary battery manufactured as described above was charged and discharged 50 times at 25°C, disassembled, and the cross-section of the electrode tab of the positive electrode was observed to check whether each insulating layer was detached.

And, the results of whether the insulation layer was detached or not are shown in Table 1 below.

Adhesion (gf/20mm) Results of insulation layer detachment after cell manufacturing dry Wet Wet (ultrasonic) Example 1 21.4 19.3 17.1 normal Example 2 18.5 17.1 16.2 normal Comparative Example 1 21.7 19.3 12.1 Insulation layer detachment Comparative Example 2 21.8 19 11.5 Insulation layer detachment

Looking at Table 3, we could see the difference in the adhesive strength of the insulation layer in a dry state, in a wet state, and in the wet adhesive strength of the insulation layer using ultrasonic waves.

In particular, when comparing Example 1 with Comparative Examples 1 and 3, the dry adhesion of the insulation layer was similar to each other at 21.4 gf/20mm, 21.7 gf/20mm, and 21.5 gf/20mm, respectively, but there was a difference between the wet adhesion of the insulation layer and the wet adhesion of the insulation layer using ultrasonic waves. In particular, the wet adhesion of Example 1 and Comparative Examples 1 and 2 were similar to each other, and the wet adhesion of the insulation layer using ultrasonic waves was 17.1 gf/20mm, 12.1 gf/20mm, and 11.5 gf/20mm, respectively, showing that Example 1 had a higher wet adhesion of the insulation layer using ultrasonic waves than Comparative Examples 1 and 2.

In addition, as a result of observing whether the insulating layer detached after cell manufacturing, detachment of the insulating layer occurred in the electrodes of Comparative Examples 1 and 2, which had low wet adhesive strength.

This has the effect of simulating the internal state of an electrode in a secondary battery by evaluating the adhesive strength of an insulating layer after applying ultrasonic waves while the electrode is immersed in an electrolyte, thereby increasing the reliability of predicting detachment of the insulating layer.

The above description is merely an illustrative description of the technical idea of the present invention, and those skilled in the art will appreciate that various modifications and variations may be made without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to explain it, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

100: Wet adhesion measurement system of insulation layer
110: Test board
111: Insulating layer
1111: Self-standing area
112: Metal specimen
120: Fixed jig
121: Settlement
122: 1st fixed part
1221: Clamping Absence
123: Second fixed part
1231: Clamping Absence
1232: Conclusion Home
1233: Fastening protrusion
130: Adhesion Measuring Device
131: Grip
1311: Joe Pace
132: Output section

Claims (17)

A step of forming a self-standing region of the insulating layer;
A step of wetting a metal specimen on which an insulating layer has been formed in an electrolyte;
A step of applying ultrasonic waves to an electrolyte solution in which a metal specimen is impregnated; and
A step of checking the adhesion of an insulating layer formed on a metal specimen is included.
The step of immersing the above metal specimen in an electrolyte is:
The metal specimen, excluding the self-standing area of the insulating layer, is immersed in the electrolyte.
A method for measuring the wet adhesion of an insulating layer without immersing it in an electrolyte, the self-standing area of the insulating layer.
In the first paragraph,
A method for measuring wet adhesion of an insulating layer, the step of checking the adhesion of an insulating layer formed on a metal specimen including a process of checking whether the insulating layer is swelling or detached.
In the first paragraph,
A method for measuring wet adhesion of an insulating layer, the step of checking the adhesion of an insulating layer of a metal specimen includes a process of measuring the adhesion of an insulating layer by applying a tensile force to one side of the insulating layer while fixing a metal specimen impregnated with an electrolyte and measuring the force at which the insulating layer is peeled off from the metal specimen.
In the first paragraph,
A method for measuring wet adhesion of an insulating layer, wherein the step of forming a self-standing region of the insulating layer includes a process of peeling off one end of the insulating layer so that one side of the insulating layer becomes self-standing in a direction perpendicular to a metal specimen.
delete In the third paragraph,
A method for measuring wet adhesion of an insulating layer, characterized in that the process of measuring the adhesion of the insulating layer includes a process of attaching one side of a metal specimen on which an insulating layer is not formed to a test substrate.
In the third paragraph,
A method for measuring wet adhesion of an insulating layer, characterized in that the step of measuring adhesion of the insulating layer includes a process of pulling one side of the insulating layer in a direction perpendicular to the test substrate.
In the first paragraph,
A method for measuring wet adhesion of an insulating layer, wherein the step of applying ultrasonic waves to an electrolyte is performed by a tip sonicator or a bath sonicator.
In the first paragraph,
A method for measuring wet adhesion of an insulating layer, wherein the step of applying ultrasonic waves to an electrolyte includes a process of applying ultrasonic waves of 1 kHz to 200 kHz.
In the first paragraph,
A method for measuring wet adhesion of an insulating layer, characterized in that the electrolyte contains at least one organic solvent selected from the group consisting of ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, propylene carbonate (PC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinylethylene carbonate (VEC), butylene carbonate, ethyl propionate, ethyl butyrate, dimethyl sulfoxide, dimethyl formamide, dimethyl acetamide, gamma-valerolactone, m-butyrolactone, and tetrahydrofuran.
In the first paragraph,
A method for measuring wet adhesion of an insulating layer, wherein the metal specimen is made of aluminum, copper or an aluminum alloy.
In the first paragraph,
A method for measuring wet adhesion of an insulating layer, characterized in that the insulating layer comprises a binder polymer; or an inorganic particle and a binder polymer.
A test substrate to which a metal specimen immersed in an electrolyte is attached;
A fixing jig for fixing a test substrate to which a metal specimen having a self-standing area formed thereon is attached;
A tank containing an electrolyte inside and impregnated with a metal specimen having an insulating layer formed thereon;
An ultrasonic disperser that applies ultrasonic waves to an electrolyte solution in which a metal specimen is impregnated; and
It includes a gripping part that holds a self-standing area of an insulating layer, and an adhesive measuring device that applies a tensile force to the held insulating layer and measures the force at which the insulating layer is peeled off from a metal specimen.
The electrolyte contained in the above tank contains:
The metal specimen, excluding the self-standing area of the insulating layer, is immersed in the electrolyte.
Self-standing area of the insulating layer is a system for measuring the wet adhesion of the insulating layer without immersion in electrolyte.
In Article 13,
A system for measuring the wet adhesion of an insulating layer, characterized in that the ultrasonic disperser is a tip sonicator or a bath sonicator.
delete In Article 13,
A fixed jig is a fixture on which a test board is fixed; and
It is installed on the mounting part and includes first and second fixing parts in the form of bars that fix one side and the other side of the test board, respectively.
A system for measuring wet adhesion of an insulating layer, wherein one side of the second fixed part is rotatably connected by a hinge pin.
In Article 13,
A wet adhesion measurement system of an insulating layer, characterized in that the adhesion measurement device is a 90° peel tester.