Method of measuring surface energy of metal foil

Abstract

The present invention relates to a method for measuring the surface energy of a metal foil using a surface energy measuring device capable of uniformly applying a measuring reagent to the surface of the metal foil, comprising: a) a step of placing the metal foil on a measuring table; b) a step of injecting a measuring reagent into the surface energy measuring device; c) a step of mounting the surface energy measuring device on a jig; d) a step of moving the measuring table to place the surface energy measuring device on the surface of the metal foil; and e) a step of moving the measuring table (3000) to apply the measuring reagent in a line shape to the surface of the metal foil.

Description

Technology Field

[0001] The present invention relates to a surface energy measurement method capable of accurately measuring the surface energy of a metal foil using a surface energy measuring device capable of uniformly applying a measuring reagent to the surface of the metal foil. Background Technology

[0003] With the increasing technological development and demand for mobile devices such as smartphones, laptops, and digital cameras, technologies related to rechargeable secondary batteries are becoming more active. Furthermore, secondary batteries are being applied to electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), and energy storage devices (ESS) as alternative energy sources to fossil fuels that cause air pollutants.

[0004] Currently, widely used types of rechargeable batteries include lithium-ion batteries, lithium-polymer batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries.

[0005] Such secondary batteries are generally formed by housing the electrode assembly and electrolyte, etc., inside a battery case.

[0006] Here, the electrode assembly may be composed of, but is not limited to, a jelly-roll type assembly having a structure in which a separator is interposed between long sheet-type positive and negative electrodes and then wound; a stack type assembly having a structure in which rectangular positive and negative electrodes are stacked with a separator interposed between them; a stack-folding type assembly in which unit cells are wound by a long separating film; or a lamination-stack type assembly in which battery cells are stacked with a separator interposed between them and attached to one another.

[0007] Meanwhile, a method for manufacturing the electrode of such a secondary battery involves dispersing an active material, a conductive material, and a binder in a solvent to produce a slurry, which is then applied onto an electrode current collector and dried.

[0008] Metal foil is generally used as the electrode current collector, and in particular, aluminum foil is mainly used as the positive electrode current collector, while copper foil is mainly used as the negative electrode current collector.

[0009] As such, metal foil is manufactured by cold rolling to possess the necessary characteristics as a current collector, and as a result, even if the rolling oil is removed in the post-rolling process, some rolling oil remains on the surface of the metal foil.

[0010] If such rolling oil remains on the surface of the metal foil above a certain level, the coating performance may be reduced during the process of applying a slurry onto the electrode current collector.

[0011] Therefore, it is necessary to manage the quality of the electrode current collector by measuring its surface energy prior to the coating process and maintaining it at a certain level.

[0012] However, the conventional method for measuring surface energy according to Patent Document 1, which measures the contact angle by dropping a liquid onto the surface of a measurement target as shown in Fig. 1, can measure accurate surface energy values, but it requires complex equipment like that of Patent Document 1 and has the problem of not being suitable for easy and rapid measurement on a production line.

[0013] Accordingly, as shown in FIG. 2, a method is used to apply a measuring reagent (20) in the form of a long line on the surface of a metal foil (30) using a cotton swab (10), and to determine whether the surface energy of the metal foil (30) satisfies the desired level by checking the level at which the line breaks.

[0014] However, while it is important to maintain a constant amount of the measurement reagent and the thickness of the line for the accuracy of the measurement, the above conventional measurement method has a problem in that differences may occur in the amount of the measurement reagent (20) and the thickness of the line depending on the shape of the cotton swab (10), the angle formed between the surface of the cotton swab (10) and the metal foil (30), and the force applied to the cotton swab (10).

[0015] In particular, since the measuring person draws a line on the surface of the metal foil (30) using a cotton swab (10) soaked in the measuring reagent (20), it is difficult to maintain constant pressure applied to the cotton swab (10).

[0016] Meanwhile, Dyne Pens are sometimes used instead of cotton swabs, but even when using a Dyne Pen to apply the measurement reagent, there is a problem with inconsistent application of the reagent and difficulty in reusing the Dyne Pen due to contamination, which also causes an increase in costs. Prior art literature

[0018] Korean Registered Patent Publication No. 1952307 The problem to be solved

[0019] The present invention aims to solve the above-mentioned problems by providing a method for measuring surface energy using a surface energy measuring device equipped with a replaceable cotton ball and capable of uniformly applying a measuring reagent to the surface of a metal foil. means of solving the problem

[0021] A surface energy measuring method according to the present invention for achieving the above-mentioned purpose is a method for measuring the surface energy of a metal foil using a surface energy measuring device (1000) capable of uniformly applying a measuring reagent to the surface of the metal foil, and is characterized by comprising: a) a step of positioning the metal foil on a measuring table (3000); b) a step of injecting the measuring reagent into the surface energy measuring device (1000); c) a step of mounting the surface energy measuring device (1000) on a jig (2000); d) a step of moving the measuring table (3000) to position the surface energy measuring device (1000) on the surface of the metal foil; and e) a step of moving the measuring table (3000) to apply the measuring reagent in a line shape to the surface of the metal foil.

[0022] In addition, in the surface energy measuring method according to the present invention, the surface energy measuring device (1000) comprises a body part (100) for storing and discharging the measuring reagent and a coating part (200) for applying the measuring reagent supplied from the body part to the surface of the metal foil, and the coating part (200) comprises a cotton ball (240) that contacts the metal foil and applies the measuring reagent to the surface of the metal foil.

[0023] In addition, the surface energy measurement method according to the present invention is characterized by further including a step of determining whether there is a defect by sensing the line shape of the measurement reagent using a camera (4000) after step e).

[0024] In addition, in the surface energy measurement method according to the present invention, step f) is characterized by determining whether there is a defect based on the degree of breakage of the line sensed by the camera.

[0025] In addition, the surface energy measurement method according to the present invention is characterized in that the jig is equipped with a push pull gauge.

[0026] In addition, in the surface energy measurement method according to the present invention, step d) is characterized by including the step of moving the measurement table in a vertical direction to reach the pressure set in the tensile-compressive gauge.

[0027] In addition, the surface energy measurement method according to the present invention is characterized by determining whether there is a defect by repeatedly performing steps d), e), and f) at different locations on the metal foil.

[0028] In addition, the surface energy measuring method according to the present invention is characterized by including the step of replacing the cotton ball of the surface energy measuring device after determining whether the metal foil is defective.

[0029] In addition, in the surface energy measurement method according to the present invention, the measurement reagent is characterized by comprising ethylene glycol monoethyl ether.

[0030] In addition, in the surface energy measurement method according to the present invention, the metal foil is characterized as being an aluminum (Al) foil. Effects of the invention

[0032] The surface energy measurement method of the present invention has the advantage of being able to uniformly apply a measurement reagent to the surface of a metal foil at a constant pressure by using a finely movable measuring table and a tensile-compressive gauge.

[0033] In addition, the surface energy measurement method of the present invention has the advantage of being able to measure the surface energy of a metal foil simply and accurately by uniformly applying a measurement reagent and sensing the applied state with a camera. Brief explanation of the drawing

[0035] Figure 1 is a schematic diagram illustrating a conventional method of measuring surface energy by measuring the contact angle. Figure 2 is a schematic diagram showing a method of measuring surface energy by soaking a conventional cotton swab in a measuring reagent. FIG. 3 is a schematic diagram showing a surface energy measuring device according to one embodiment of the present invention. Figure 4 is an enlarged view of the coating portion inside the dotted line of Figure 3. FIG. 5 is a drawing showing the shape of a surface energy measuring device with a cotton ball removed according to one embodiment of the present invention. FIG. 6 is a diagram showing the behavior of a stopper before (a) and after (b) pressurization in a surface energy measuring device according to one embodiment of the present invention. FIG. 7 is a schematic diagram illustrating a surface energy measurement method according to one embodiment of the present invention. Specific details for implementing the invention

[0036] In this application, terms such as “comprising,” “having,” or “having” are intended to specify the existence of the features, numbers, steps, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0037] In addition, the same reference numerals are used for parts having similar functions and operations throughout the drawings. Throughout the specification, when a part is described as being connected to another part, this includes not only cases where they are directly connected, but also cases where they are indirectly connected with other elements in between. Furthermore, unless specifically stated otherwise, the inclusion of a certain component does not exclude other components but implies that additional components may be included.

[0039] Hereinafter, a surface energy measuring device according to the present invention will be described with reference to the attached drawings.

[0040] FIG. 3 is a schematic diagram showing a surface energy measuring mechanism according to one embodiment of the present invention, and FIG. 4 is an enlarged view of the coating portion inside the dotted line of FIG. 3.

[0041] Referring to FIGS. 3 and FIGS. 4, the surface energy measuring device (1000) of the present invention is described as follows: the surface energy measuring device (1000) of the present invention largely comprises a body part (100) that stores and discharges a measuring reagent, and a coating part (200) that uniformly applies the measuring reagent discharged from the body part to the surface of a metal foil to be measured for surface energy.

[0042] First, the body part (100) includes a reagent storage part (110), a reagent injection port (120), a reagent discharge port (130), a discharge control part (140), and a discharge pipe (150).

[0043] The reagent storage section (110) is a section that stores a certain amount of measuring reagent, and since it can store a sufficient amount of measuring reagent, it is possible to measure the surface energy of the metal foil without supplying additional measuring reagent.

[0044] Accordingly, unlike when using conventional cotton swabs, the inconvenience of frequently injecting reagent can be eliminated, and the reagent storage part (110) can be formed of a transparent material that allows the internal reagent to be checked and a scale marked so that the amount of reagent remaining can be checked immediately.

[0045] The material of the reagent storage section (110) can be appropriately selected within a range that has enough transparency to check the remaining amount of the reagent inside and has no reactivity with the reagent stored inside.

[0046] In addition, the shape of the reagent storage section (110) can be either a cylindrical shape or a polygonal shape, and the thickness is not particularly limited but can be appropriately selected within a range that is easy for the user to use.

[0047] The upper part of the reagent storage unit (110) is provided with a reagent injection port (120) for injecting a measuring reagent into the reagent storage unit (110), and the reagent injection port (120) can be opened and closed.

[0048] Additionally, a reagent discharge port (130) for discharging a measurement reagent from the reagent storage unit (110) is provided at the bottom of the reagent storage unit (110), and a discharge control unit (140) for controlling the amount of measurement reagent discharged is connected to the reagent discharge port (130).

[0049] Such an emission control unit (140) may utilize various known devices such as valves, and a dial gauge that can easily control the emission amount is preferred.

[0050] Additionally, a discharge pipe (150) is provided at the bottom of the reagent discharge port (130) to guide the measurement reagent discharged from the reagent discharge port (130) to a desired location in the application section (200).

[0051] Meanwhile, the coating portion (200) includes a connecting portion (210), a cover portion (220), a stopper (230), and a cotton ball (240).

[0052] The upper part of the connecting part (210) is connected to the body part (100), and the lower part is equipped with a stopper (230) and a cotton ball (240).

[0053] The cover portion (220) is provided in a shape that encloses the connecting portion (210), the stopper (230), and the cotton ball (240), and has a shape in which the upper part connected to the body portion (100) is wider and the lower part where the cotton ball (240) is located is narrower.

[0054] The cover portion (220) having such a shape has a slanted side, and the discharge pipe (150) can be provided in such a way that the end through which the measurement reagent is discharged contacts the inner wall surface of the cover portion (220).

[0055] In this case, the measuring reagent discharged from the discharge pipe (150) seeps into the cotton ball (240) at the bottom along the inner wall of the cover part (200).

[0056] Accordingly, by using the discharge control unit (140) to appropriately control the discharge amount of the measuring reagent and contacting the cotton ball (240) with the metal foil to measure surface energy, a certain amount of measuring reagent can be continuously supplied to the cotton ball (240), and accordingly, the accuracy of the surface energy measurement is also increased.

[0057] Cotton balls (240) are formed by bundling cotton or cotton into a ball shape, and can be compressed by pressure and have the characteristic of absorbing solution well. They can be appropriately selected and used from among various known cotton balls (240).

[0058] FIG. 5 is a drawing showing the shape of a surface energy measuring device with a cotton ball removed according to one embodiment of the present invention.

[0059] In addition, the cotton ball (240) in the surface energy measuring device (1000) of the present invention can be easily removed and replaced after use as shown in FIG. 5, thereby preventing contamination by rolling oil remaining on the metal foil.

[0060] FIG. 6 is a diagram showing the behavior of a stopper before (a) and after (b) pressurization in a surface energy measuring device according to one embodiment of the present invention.

[0061] Referring to FIGS. 3, 4 and 6, the stopper (230) of the present invention is used to control the amount of measurement reagent applied by adjusting the pressure applied to the cotton ball (240). It includes a spring (231) that adjusts the pressure applied to the cotton ball (240), a fixing part (232) located above the spring (231) that fixes the spring (231), and a pressing part (233) located below the spring (231) that is in contact with the cotton ball (240).

[0062] Meanwhile, since the amount of measuring reagent applied to the surface of the metal foil may vary depending on the pressure applied to the cotton ball (240) supplied with the measuring reagent, it is necessary to control this.

[0063] Therefore, if the stopper (230) is provided on the upper part of the cotton ball, even if the pressure applied to the cotton ball (240) for measuring surface energy exceeds a certain level, the stopper (230) can absorb part of the pressure and prevent excessive pressure from being applied to the cotton ball (240).

[0064] That is, when a surface energy measuring device (1000) is placed on a metal foil and pressure is applied to a cotton ball (240), the cotton ball (240) will have a height difference (h1) after applying pressure (b) compared to before applying pressure (a) as shown in FIG. 6.

[0065] If pressure exceeding a certain value is applied to the cotton ball (240), the pressure is transmitted to the stopper (230), and the stopper (230) absorbs some of this pressure, thereby compressing the spring (h2) and preventing excessively high pressure from being applied to the cotton ball (240) (h1 > h2).

[0066] These stoppers (230) can be manufactured by appropriately selecting the elasticity of the spring (231) to match the desired pressure range.

[0068] FIG. 7 is a schematic diagram illustrating a surface energy measurement method according to one embodiment of the present invention.

[0069] Looking at the method for measuring the surface energy of a metal foil using the surface energy measuring device (1000) of the present invention described above and FIG. 7, the surface energy measuring method includes a) a step of placing the metal foil on a measuring table (3000), b) a step of injecting a measuring reagent into the surface energy measuring device (1000), c) a step of mounting the surface energy measuring device (1000) on a jig (2000), d) a step of moving the measuring table (3000) to place the surface energy measuring device (1000) on the surface of the metal foil, and e) a step of moving the measuring table (3000) to apply the measuring reagent in a line shape to the surface of the metal foil.

[0070] In addition, the method further includes a step of applying a measuring reagent to the surface of a metal foil and then using a camera (4000) to sense the line shape of the measuring reagent to determine whether it is defective.

[0071] The defect can be determined based on the degree of breakage of the line sensed by the camera.

[0072] For example, if the line coated with the measurement reagent breaks within a certain period of time, it is judged as defective.

[0073] Various known cameras, such as a CCD camera, can be used as the camera (4000) for sensing the line coated with such a measuring reagent.

[0074] Meanwhile, the jig (2000) on which the surface energy measuring device (1000) is mounted is equipped with a push-pull gauge, so that a desired pressure can be applied between the surface energy measuring device (1000) and the metal foil in conjunction with the measuring table (3000).

[0075] Additionally, the measuring table (3000) can be movable in the forward, backward, left, right, horizontal, and vertical directions, with a metal foil placed on it.

[0076] In particular, it is desirable that the measuring table (3000) be capable of fine movement in the mm range for accurate measurement of surface energy, and for this purpose, a servo motor or the like may be provided as a driving means.

[0077] This measuring table (3000) can finely control vertical movement in conjunction with the tensile-compressive gauge of the jig (2000) so that the pressure between the surface energy measuring device (1000) and the metal foil has a set value.

[0078] In addition, it can automatically move at a uniform speed in the horizontal direction according to the set value and uniformly apply the measuring reagent to the surface of the metal foil.

[0079] Meanwhile, since metal foils used in mass production have a large surface area, there may be variations in surface energy depending on the location. Therefore, to measure the surface energy of the metal foil, it is desirable to draw two or more lines at different locations on the metal foil using a measuring reagent.

[0080] In other words, the measurement method examined above involves drawing a line on the metal foil through steps d) and e), and repeating the step of sensing the line to determine whether it is defective.

[0081] Meanwhile, the cotton ball (240) of the surface energy measuring device (1000) may be replaced appropriately in consideration of contamination by rolling oil, etc. remaining on the metal foil, and may be replaced after the measurement of one metal foil is completed, but is not limited thereto.

[0082] The measurement reagents used for such surface energy measurement may be used either individually or by mixing two or more known measurement reagents in appropriate proportions, depending on the desired Dyne index.

[0083] For example, when measuring the surface energy of an aluminum (Al) foil used as an anode current collector, ethylene glycol monoethyl ether and formamide can be mixed in appropriate proportions and used as a measuring reagent.

[0084] The ratio for mixing the two measurement reagents can be selected by referring to the announced ratios to match the required multi-factor index.

[0085] The metal foil determined to be good in the surface energy measurement step above can be used as an electrode current collector.

[0086] That is, an electrode can be manufactured by applying a slurry containing active material, etc. onto a metal foil, and a battery cell can be manufactured using the electrode manufactured in this way.

[0087] In addition, battery cells manufactured in this way can be produced in the form of modules or packs and used as power sources for various devices.

[0089] As specific parts of the present invention have been described in detail above, it is obvious to those skilled in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of the invention, and that various changes and modifications are possible within the scope and spirit of the invention, and that such variations and modifications fall within the scope of the appended claims. Explanation of the symbols

[0091] 1000 : Surface energy measuring instrument 100 : Body part 110: Reagent storage area 120: Reagent injection port 130 : Reagent outlet 140: Emission control unit 150 : Discharge pipe 200 : Coating part 210 : Connection part 220 : Cover part 230 : Stopper 231 : Spring 232 : Fixed part 233 : Pressurizing part 240 : Cotton Ball 2000 : Jig 3000 : Measurement table 4000 : Camera

Claims

Claim 1 A method for measuring the surface energy of a metal foil using a surface energy measuring device capable of uniformly applying a measuring reagent to the surface of the metal foil, comprising: a) a step of placing the metal foil on a measuring table; b) a step of injecting the measuring reagent into the surface energy measuring device; c) a step of mounting the surface energy measuring device on a jig; d) a step of moving the measuring table to place the surface energy measuring device on the surface of the metal foil; and e) a step of moving the measuring table to apply the measuring reagent in a line shape to the surface of the metal foil; wherein the surface energy measuring device comprises a body portion for storing and discharging the measuring reagent and a coating portion for applying the measuring reagent supplied from the body portion to the surface of the metal foil, the coating portion comprises a cotton ball that contacts the metal foil and applies the measuring reagent to the surface of the metal foil, the coating portion further comprises a stopper, and the stopper comprises a spring that regulates the pressure applied to the cotton ball. Claim 2 delete Claim 3 A surface energy measurement method according to claim 1, further comprising the step of f) after step e) of sensing the line shape of the measurement reagent using a camera to determine whether it is defective. Claim 4 A surface energy measurement method according to paragraph 3, wherein step f) determines whether there is a defect based on the degree of breakage of the line sensed by the camera. Claim 5 A surface energy measurement method according to paragraph 3, characterized in that the jig is equipped with a push-pull gauge. Claim 6 A surface energy measurement method according to claim 5, wherein step d) comprises the step of moving the measurement table in a vertical direction to reach the pressure set on the tensile-compressive gauge. Claim 7 A surface energy measurement method according to claim 3, characterized by repeatedly performing steps d), e), and f) at different locations on the metal foil to determine whether there is a defect. Claim 8 A surface energy measuring method according to claim 7, characterized by including the step of replacing the cotton ball of the surface energy measuring device after determining whether the metal foil is defective. Claim 9 A method for measuring surface energy according to claim 3, characterized in that the measuring reagent comprises ethylene glycol monoethyl ether. Claim 10 A surface energy measurement method according to claim 9, characterized in that the metal foil is an aluminum (Al) foil.

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