JP5655773B2 - Electrode material application amount measurement method - Google Patents

Description

  The present invention relates to a coating amount measuring method for measuring a coating amount of an electrode material applied to the surface of a substrate. More specifically, the present invention relates to a method for measuring the coating amount of an electrode material that performs off-line actual weight measurement.

  In recent years, electric vehicles such as hybrid vehicles and electric vehicles equipped with a motor as a drive source are becoming popular. Such an electric vehicle is equipped with a secondary battery for charging and discharging. The electrode plate of the secondary battery is manufactured by applying an active material to a strip-shaped metal foil (base material). Specifically, in the manufacturing process of the electrode plate, a paste-like active material is applied to both surfaces of the metal foil, the active material is dried, and the dried active material is rolled with a metal foil with a press roll. Cutting thin films into appropriate widths and lengths has been performed.

  In this secondary battery, when charging or discharging, ions are occluded or released between the positive electrode active material contained in the coating film of the positive electrode plate and the negative electrode active material contained in the coating film of the negative electrode plate. Done. In order to appropriately perform occlusion and release of ions, a paste-like active material needs to be uniformly applied to the surfaces of the positive electrode plate and the negative electrode plate.

Therefore, the application amount of the electrode material applied to the electrode plate is measured. As a method for measuring the coating amount, for example, an image is taken over the entire length of the electrode plate with a CCD sensor, the film thickness of the battery material on the electrode plate is measured based on the imaging data, and the coating amount is feedback controlled. (See Patent Document 1). In addition, there is also a technique in which the amount of transmission is measured by irradiating a coating with radiation such as β-rays or X-rays, and the amount of electrode material applied per unit area is measured based on the measured amount of transmission (see Patent Document 2).
However, such a measuring method cannot measure the coating amount of the electrode material at a low cost because the measuring device is expensive.

  Therefore, in order to measure the application amount of the electrode material at a low cost, the electrode plate coated with the electrode material is sampled (cut out), and the application amount of the sample is measured by actual weight measurement. In such a measurement method, for example, as shown in FIG. 10, a part is cut out from a belt-like electrode plate coated with a coating film (electrode material) (see FIG. 10A) to obtain a sample. (See FIG. 10B), and the weight of the sample is measured. Thereafter, the sample coating film is scraped off (see FIG. 10C), and the weight is measured again. Then, the coating amount is calculated from the measured weight difference.

JP 2007-066821 A Japanese Patent Laid-Open No. 9-161792

  However, the conventional method for measuring the coating amount by actual weight measurement has a problem in that the measurement time is very long because it takes a long time to remove the electrode member. Thus, the removal work takes a lot of time because the electrode is formed by forming a coating film of about 50 μm on a very thin electrode plate (base material) of about 10 to 15 μm, so that it does not break. This is because, after the coating film (electrode material) is roughly removed from the electrode plate using a resin blade, it is necessary to perform a special removal operation of wiping with a sponge-like member.

Moreover, since the surface of the electrode plate has minute irregularities, it is difficult to completely remove the coating film from the electrode plate, and a measurement error occurs, so that the coating amount cannot be measured with high accuracy.
Furthermore, since the weight per unit area was calculated by dividing the weight of the cut sample (see FIG. 10B) by the area, it was impossible to grasp the variation in the coating amount.

  Therefore, the present invention has been made to solve the above-described problems, and the amount of the electrode material applied to the surface of the base material can be measured inexpensively, easily and accurately in a short time. It aims to provide a method.

One aspect of the present invention made in order to solve the above problems is that a coated part to which an electrode material is applied and an uncoated part that is located on both sides of the coated part and to which no electrode material is applied are in a band shape. In the measuring method for measuring the coating amount of the electrode material on the electrode plate formed in the width direction of the substrate, the electrode plate on which the coated part and the uncoated part are formed is the same in the substrate transport direction. at transverse direction at the position, the measuring coated portion and said punching step of punching out the respective between uncoated portion, respectively the weight on the coated portion and a portion in which the punched out respectively in the uncoated portions at the punching step A weight calculation step for calculating the weight per unit area, and a coating amount calculation step for obtaining the coating amount of the electrode material based on the difference in weight per unit area calculated in the weight calculation step. It is characterized by.

  In this coating amount measuring method, in the punching process, the coated portion and the uncoated portion of the electrode plate are punched in the width direction at the same position in the substrate transport direction. Thereby, a sample is acquired about a coated part and an uncoated part, respectively. Next, in the weight calculation process, the weights of the coated part and uncoated part samples obtained in the punching process are measured. And the weight per unit area is calculated about the sample of a coating part and an uncoated part, respectively. Thereafter, in the coating amount calculation step, the coating amount of the electrode material is obtained based on the weight difference per unit area between the coated portion and the uncoated portion calculated in the weight calculation step. That is, the coating amount of the electrode material is calculated by subtracting the weight per unit area of the uncoated part that has been punched from the weight per unit area of the stamped coated part.

Since the coating amount of the electrode material is measured in this way, the weights of the coated portion and the uncoated portion of the electrode plate can be accurately obtained, so that the coating amount of the electrode material can be accurately measured. Moreover, since the removal operation of an electrode member becomes unnecessary, measurement time can be shortened very much. Furthermore, since the measuring device does not become expensive, it is possible to measure the coating amount of the electrode material at a low cost.
Therefore, according to this coating amount measuring method, the coating amount of the electrode material can be accurately measured with a low cost and in a short time.

  In the coating amount measuring method described above, in the punching step, it is desirable to punch the coating part at two or more locations.

  By doing so, it is possible to measure the application amount of the electrode material with high accuracy at a low cost, in a short time, and to grasp variations in the application amount in the width direction of the electrode plate.

  In the coating amount measuring method described above, in the punching step, it is desirable to punch the coating portion with rounded corners.

  By doing in this way, when punching out the coating part of an electrode plate, peeling of the electrode material from an electrode plate can be suppressed. Therefore, the weight of the coated part can be measured more accurately. Thereby, the application amount of the electrode material can be measured with higher accuracy.

In this case, the corner portion may be punched so that the R chamfer size of the corner portion is equal to or greater than R5 (mm) .

  By doing in this way, peeling of the electrode material from an electrode plate can be suppressed reliably. Therefore, the weight of the coated part can be measured more accurately. Thereby, the application amount of the electrode material can be measured with higher accuracy.

  According to the electrode material application amount measuring method of the present invention, as described above, the electrode material application amount can be accurately measured in a short time, at a low cost.

It is a top view which shows schematic structure of an electrode plate. It is sectional drawing which shows the cross section of the width direction of an electrode plate. It is a figure which shows typically the location and shape which are pierce | punched. It is a figure which shows the comparison result of the measurement time required in order to measure a coating amount. It is a figure which shows the comparison result of the measurement dispersion | variation in application amount. It is the figure which expanded the corner | angular part of the coating part sample which punched the coating part. It is a figure which shows the result of the measurement dispersion | variation in the coating amount by the shape (size of R) in the corner | angular part of a coating part sample. It is a figure which shows an example in the case of punching a coating part in multiple places. It is a figure which shows the application quantity of each coating part sample punched in each position shown in FIG. It is a figure which shows the procedure of the conventional coating amount measuring method.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a method for measuring an application amount of an electrode material according to the present invention will be described below in detail with reference to the drawings. Here, the case where the application amount of the coating material (coating film) applied to the base material is measured in the manufacturing process of the electrode plate that becomes the electrode of the lithium ion secondary battery mounted on the electric vehicle is illustrated.

Therefore, first, an electrode plate for measuring the coating amount will be briefly described with reference to FIGS. FIG. 1 is a plan view showing a schematic configuration of an electrode plate. FIG. 2 is a cross-sectional view showing a cross section of the electrode plate in the width direction.
As shown in FIGS. 1 and 2, the electrode plate 10 has a coating film 21 formed on both surfaces of a belt-like substrate 20. The coating film 21 is bonded to the base material 20 by applying a coating material (electrode material) to the base material 20 and then drying it. The coating material is a conductive paste in which an active material, a conductive auxiliary material, a binder, a solvent, and the like are kneaded. The coating film 21 is applied in the vicinity of the center of the base material 20 in the width direction (vertical direction in FIG. 1), and this portion serves as a coating portion 22. On the other hand, uncoated portions 23 to which the coating film 21 is not applied are formed at both ends in the width direction of the substrate 20.

  The coating width of the left coating film 21 in FIG. 2 is the same as the coating width of the right coating film 21 in FIG. Further, the position in the width direction of the coating film 21 on the left side in FIG. 2 is the same as the position in the width direction of the coating film 21 on the right side in FIG. That is, the coating film 21 on the left side in FIG. 2 is in a position directly behind the coating film 21 on the right side in FIG. In this embodiment, the thickness of the base material 20 is about 10 μm, and the thickness of the coating film 21 is about 40 μm before drying and about 30 μm after drying.

  There are two types of electrode plates 10, a positive electrode and a negative electrode. An aluminum foil or the like can be used as the base material 20 for the positive electrode plate of the lithium ion secondary battery. The active material contained in the coating material for forming the coating film 21 of the positive electrode may be any material that occludes lithium ions during charging and releases lithium ions during discharging. For example, lithium cobaltate, nickel Examples thereof include lithium transition metal composite oxides such as lithium oxide and lithium manganate.

  On the other hand, a copper foil or the like can be used as the base material 20 for the negative electrode plate of the lithium ion secondary battery. The active material contained in the coating material forming the negative electrode coating film 21 may be any material that occludes lithium ions during discharge and releases lithium ions during charging. For example, natural graphite, artificial graphite And amorphous amorphous carbon such as soft carbon and hard carbon.

  Here, although the material is different between the positive electrode plate and the negative electrode plate as described above, there is no great difference in the width and thickness of the base material 20 and the coating film 21. Further, as shown in FIG. 2, both the positive electrode plate and the negative electrode plate are formed by coating the coating film 21 on both surfaces of the substrate 20. For this reason, the coating amount measuring method according to the present embodiment can be applied to either the positive electrode plate or the negative electrode plate of the lithium ion secondary battery. Therefore, below, it demonstrates as the electrode plate 10, without distinguishing especially a positive electrode and a negative electrode.

Next, a method for measuring the coating amount of the coating material (coating film) applied to the above electrode plate will be described with reference to FIG. FIG. 3 is a diagram schematically showing a location and shape to be punched.
In the coating amount measurement method according to the present embodiment, a sample is obtained offline and the coating amount of the coating film 21 is measured. Specifically, the punching step, the weight calculation step, and the coating amount calculation step are performed in this order, and the coating amount of the coating material (coating film 21) applied to the substrate 20 is measured. Therefore, each step will be described below.

  First, in the punching process, the electrode plate 10 is punched with a punching machine as shown in FIG. Specifically, each of the coated part 22 and the uncoated part 23 is rectangular in the width direction (up and down direction in FIG. 3) of the electrode plate at the same position in the substrate transport direction (left and right direction in FIG. 3). The electrode plate 10 is punched into a shape. Thereby, the coated part sample 22a and the uncoated part sample 23a are cut out from the electrode plate 10.

Subsequently, in the weight calculation process, the weight per unit area is calculated for each of the coated part sample 22a and the uncoated part sample 23a acquired in the punching process. That is, first, the weights of the coated part sample 22a and the uncoated part sample 23a are measured. And since each area of the coating part sample 22a and the uncoated part sample 23a is known (calculatable), from the measured weight and each area, the weight A per unit area of the coating part sample 22a ( g / mm ² ) and the weight B (g / mm ² ) per unit area of the uncoated part sample 23a are calculated.

In the coating amount calculation step, the coating amount of the coating film 21 is obtained based on the weight difference between the coated portion sample 22a and the uncoated portion sample 23a calculated in the weight calculating step. That is, the weight of the base material 20 included in the weight of the coated part sample 22a is regarded as the weight of the uncoated part sample 23a, and the coating amount C (g / mm ² ) of the coated film 21 is expressed as C = Obtained by AB.

  Thus, in the coating amount measuring method according to the present embodiment, the removal work of the coating film 21 is unnecessary, and therefore the measurement time can be shortened very much. In addition, since no sensor or radiation is used, the measuring device does not become expensive, so that the coating amount of the coating film 21 can be measured at a low cost. And since each weight A and B of the coating part sample 22a and the uncoated part sample 23a can be calculated | required correctly, the coating amount C of the coating film 21 can be measured with a sufficient precision.

  Here, since the coating amount of the coating film 21 was measured by the conventional coating amount measuring method by actual weight measurement and the coating amount measuring method according to the present embodiment, the comparison results are shown in FIGS. 4 and 5. . FIG. 4 is a diagram showing a comparison result of measurement time necessary for measuring the coating amount of the coating film. FIG. 5 is a diagram showing a comparison result of measurement variations of the coating amount of the coating film. 4 and 5 show the comparison results with the measurement result by the coating amount measurement method in the conventional actual weight measurement as “100”.

As is apparent from FIG. 4, according to the coating amount measuring method according to the present embodiment, it can be seen that the measuring time is greatly shortened. More specifically, according to the coating amount measurement method according to the present embodiment, the measurement time can be shortened by about 90% compared to the conventional method.
Further, as apparent from FIG. 5, it can be seen that the measurement accuracy is improved by the coating amount measuring method according to the present embodiment. More specifically, according to the coating amount measurement method according to the present embodiment, the measurement variation (3σ: σ is a standard deviation) can be reduced by 10% compared to the conventional method, that is, the measurement accuracy can be improved by 10%. it can.

  Thus, in the coating amount measuring method according to the present embodiment, the coating amount of the coating film 21 applied to the substrate 20 is measured based on the weight difference between the coated portion sample 22a and the uncoated portion sample 23a. Therefore, the removal work of the coating film 21 is not necessary, the measurement time can be shortened and the measurement accuracy can be improved.

  Here, a modified example of the coating amount measuring method described above will be described with reference to FIGS. FIG. 6 is an enlarged view of a corner portion of a coating portion sample obtained by punching the coating portion. FIG. 7 is a diagram showing the results of measurement variation in the coating amount due to the shape (R size) at the corners of the coated part sample. FIG. 8 is a diagram illustrating an example of punching a coating portion at a plurality of locations. FIG. 9 is a diagram showing the coating amount of each coating part sample punched out at each position shown in FIG. FIG. 9 shows a comparison result in which the measurement result by the coating amount measurement method in the above embodiment is “100”.

  First, a first modification will be described with reference to FIGS. In the first modification, the corner portion is rounded when the coated portion sample is acquired. Specifically, as shown in FIG. 6, the corner portion 22c of the coating portion sample 22a is rounded by rounding off the chamfer. FIG. 6 shows only one corner in the coated part sample 22a. However, in the first modification, all four corners of the coated part sample 22a have the same size (shape). It is

  Thereby, in the 1st modification, when punching out the coating part 22 of the electrode plate 10 and acquiring the coating part sample 22a, peeling of the coating film 21 from the base material 20 can be suppressed. As a result, the weight of the coated part sample 22a can be measured more accurately. Therefore, the coating amount of the coating film 21 can be measured with higher accuracy.

The size (radius) of the R chamfer at the corner is preferably R5 (mm) or more. This is because, as shown in FIG. 7, when the size of the R chamfer is less than R5 (mm) , the measurement variation hardly changes, whereas when the size of the R chamfer is R5 (mm) or more, the measurement variation is This is because it can be made smaller. Specifically, the measurement accuracy can be improved by about 35% by setting the size of the R chamfer to R5 (mm) or more.
In addition, the upper limit of the magnitude | size of R chamfering becomes a radius when the shape of the coating part sample 22a becomes circular.

  As described above, in the first modified example, when the R chamfer size of the corner is set to R5 or more, peeling of the coating film 21 from the substrate 20 can be reliably suppressed. Therefore, the weight of the coated part sample 22a can be measured more accurately. Thereby, the application amount of the coating film 21 can be measured with higher accuracy.

  Note that if at least one corner of the coated part sample 22a is rounded, the measurement accuracy of the coating amount can be improved, but it is preferable to round all corners. This is because the improvement rate of the measurement accuracy is further increased.

  Next, a second modification will be described with reference to FIGS. In the second modification, a plurality of coating part samples are acquired. Specifically, as shown in FIG. 8, a coating part sample 22 a having the same shape (here, rectangular shape) is obtained at a plurality of places (here, six places) in the width direction of the coating part 22.

Accordingly, as shown in FIG. 9, the weight per unit area of the coating film 21 can be accurately calculated at each position in the width direction of the coating film 21. As a result, it is possible to grasp the variation in the coating amount of the coating film 21 in the width direction of the electrode plate 10. For example, in the example shown in FIG. 9, it can be seen that the distribution is such that the film thickness increases from position (1) to position (6) shown in FIG.
Also in the second modified example, as described above, the coating amount of the coating film 21 can be measured with high accuracy at a low cost and in a short time.

  In the second modification, the corners of each coated part sample 22a may be rounded as in the first modification. Thereby, the film thickness variation and the coating amount of the coating film 21 can be measured with higher accuracy.

  As described above in detail, according to the coating amount measuring method according to the present embodiment, the coated portion 22 and the uncoated portion 23 of the electrode plate 10 are respectively punched, and the coated portion sample 22a and the uncoated portion are coated. The part sample 23a is obtained, and the coating amount of the coating film 21 applied to the substrate 20 is measured based on the weight difference between the coated part sample 22a and the uncoated part sample 23a. Therefore, the removal work of the coating film 21 becomes unnecessary, the measurement time can be shortened, and the measurement accuracy can be improved.

  It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, the punching shape is exemplified as a rectangular shape, but the punching shape is not particularly limited and may be a shape whose area can be grasped (for example, a polygonal shape other than a square or a circular shape). It ’s fine.

DESCRIPTION OF SYMBOLS 10 Electrode board 20 Base material 21 Coating film 22 Coating part (coating film)
22a Coated part sample 22c Corner part 23 Uncoated part 23a Uncoated part sample

Claims (4)

The electrode material in the electrode plate in which the coated part to which the electrode material is applied and the uncoated part to which the electrode material is not applied and which is located on both sides of the coated part are formed in the width direction of the belt-like base material In the measuring method for measuring the coating amount,
The punching step of punching the electrode plate in which the coated part and the uncoated part are formed in the width direction at the same position in the substrate transport direction , respectively, in the coated part and the uncoated part,
A weight calculating step of measuring the weight of each of the portions punched in the coated portion and the uncoated portion in the punching step and calculating the weight per unit area, respectively;
A coating amount calculating step for obtaining a coating amount of the electrode material based on a difference in weight per unit area calculated in the weight calculating step;
A method for measuring an application amount of an electrode material, comprising: In the electrode material application amount measuring method according to claim 1,
In the punching step, the coating amount measurement method of the electrode material, wherein the coating part is punched at two or more locations. In the electrode material coating amount measuring method according to claim 1 or 2,
In the punching step, the coating amount measurement method for the electrode material is characterized by punching the coating portion with rounded corners. In the electrode material application amount measuring method according to claim 3,
The electrode material coating amount measuring method, wherein the corner portion has a rounded chamfer of R5 (mm) or more.

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