JP2014032767A - Method and device for manufacturing electrode for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for manufacturing an electrode for a battery capable of accurately measuring weight of the electrode by using ultrasonic waves without correction.SOLUTION: A device 30 for manufacturing an electrode for a battery includes: a drying furnace 60 for drying an electrode mixture coated on the surface of a base material 20; and a weight measurement device 80 for measuring the weight of the electrode 10 dried by the drying furnace 60 using an ultrasonic sensor 81. Between the drying furnace 60 and the weight measurement device 80, a temperature-equalizing device 70 is provided which equalizes the temperature of the electrode 10 to a desired temperature.

Description

  The present invention relates to a battery electrode manufacturing method and apparatus in which an electrode mixture layer is formed on the surface of a substrate. More specifically, the present invention relates to a battery electrode manufacturing method and apparatus for improving the measurement accuracy of the weight (weight per unit area) of the manufactured electrode.

  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 of a secondary battery is manufactured by apply | coating an active material (a positive electrode active material or a negative electrode active material) to strip | belt-shaped metal foil (base material). Specifically, in the process of manufacturing a battery electrode, a paste-like electrode mixture in which an active material and a binder are kneaded with a solvent is applied, the active material is dried, and the dried active material is pressed with a metal foil. The thin film after rolling is cut into an appropriate width and length.

  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. Therefore, if the electrode mixture is not applied with a uniform thickness (weight per unit area), current tends to concentrate on the thick part of the battery electrode during charging and discharging, and problems such as the occurrence of a short circuit are likely to occur. Therefore, in order to appropriately store and release ions, the electrode mixture needs to be applied to the surface of the base material with a uniform thickness.

  For this reason, in the battery electrode manufacturing process, the weight of the electrode having the electrode mixture layer formed on the substrate is measured. As a method for measuring the weight, for example, there is a method of measuring the weight using attenuation of ultrasonic waves. That is, by using a so-called transmission type ultrasonic sensor, a pair of sensors for transmitting and receiving ultrasonic waves are arranged at positions facing each other through the battery electrode, and the signal intensity with respect to the battery electrode, that is, for the battery The intensity of an ultrasonic signal transmitted to the electrode and transmitted through the battery electrode is measured.

  In this ultrasonic measurement, there is one disclosed in Patent Document 1 as one of techniques for improving measurement accuracy. In the technique disclosed herein, a movable sensor that continuously measures the signal strength with respect to the electrode, a reference material that is used for calibration of the movable sensor, and a fixed sensor that continuously measures the signal strength with respect to the reference material. As an initial calibration of electrode inspection by a movable sensor, the movable sensor is calibrated based on the difference in signal strength between the fixed sensor and the movable sensor relative to the air layer and the difference in signal strength between the fixed sensor and the movable sensor relative to the reference material. The signal intensity for the electrode is measured by the movable sensor, and at the same time, the signal intensity for the reference material is measured by the fixed sensor, and the movable sensor is calibrated based on the difference from the signal intensity of the fixed sensor with respect to the reference material in the initial calibration. . In this measurement technique, in order to eliminate the influence of temperature, the measurement accuracy is improved by constantly calibrating (correcting) the measurement value using a calibration sensor separately from the measurement sensor.

JP 2010-205678 A

However, the above-described electrode weight measurement technique using ultrasonic waves has a problem that a separate sensor is required for correction.
In addition, if a temperature difference occurs between the electrode for measuring the weight (thickness) and the reference material for calibration, the measured value cannot be corrected accurately, and the weight of the electrode cannot be measured accurately. There was also a problem. Such a problem occurs for the following reason. That is, in the electrode manufacturing process, as shown by a broken line in FIG. 4, the temperature of the electrode in the measurement process for measuring the weight increases according to the coating length. And if the temperature of an electrode rises, the air density near an electrode will fall. Then, since the attenuation amount of the ultrasonic wave is reduced, the measured value of the weight is increased. On the other hand, since the temperature of the reference material does not change, the attenuation of ultrasonic waves does not decrease in the calibration sensor. Therefore, as shown in FIG. 6, the amount of measurement deviation increases as the electrode temperature rises, and the weight of the electrode cannot be measured accurately.

  Accordingly, the present invention has been made to solve the above-described problems, and a battery electrode manufacturing method and apparatus capable of accurately measuring the weight of an electrode using ultrasonic waves without correction. The purpose is to provide.

  In one embodiment of the present invention made to solve the above problems, a drying step of drying an electrode mixture applied to the surface of a base material, and the weight of the electrode dried in the drying step using ultrasonic waves In the method of manufacturing a battery electrode having a weight measurement step, the temperature measurement step of uniformizing the temperature of the electrode to a desired temperature is included between the drying step and the weight measurement step. And

In this method for manufacturing a battery electrode, a temperature equalizing step for equalizing the temperature of the electrode to a desired temperature is included between the drying step and the weight measuring step. Therefore, when the weight of the electrode is measured in the weight measuring step, The electrode temperature can be kept constant. Thereby, the weight of the electrode can be accurately measured using ultrasonic waves without using an ultrasonic sensor for temperature correction.
In addition, since the influence of the electrode temperature after drying on the weight measurement using ultrasonic waves can be suppressed, the weight of the electrode is always measured accurately without being affected by changes in conditions during the drying process. can do.

  In the battery electrode manufacturing method described above, in the temperature equalizing step, a temperature adjusting roll that cools or raises the temperature of the electrode by contacting the electrode is used as an electrode transporting roll, and the temperature of the electrode is made uniform. It is desirable to make it.

  By doing in this way, the measurement accuracy of the weight of the electrode by an ultrasonic wave can be improved without performing correction only by adding a roll. In addition, a cooling roll or a temperature rising roll can be used as a temperature adjustment roll.

  In this case, in the temperature equalization step, two or more temperature adjusting rolls are arranged, and the temperature of each roll is set so that the temperature change of the electrode due to contact with each roll is 15 ° C. or less. good.

  Thus, by arranging two or more rolls and suppressing the temperature change of the electrode after drying to 15 ° C. or less, the temperature of the electrode can be surely made uniform to a desired temperature. Thereby, the measurement accuracy of the weight of the electrode by ultrasonic waves can be further improved, and generation of wrinkles on the electrode due to thermal contraction can also be suppressed. Therefore, the generation of defective products can be avoided. The reason why the temperature change of the electrode due to the contact with each roll is 15 ° C. or less is that when a temperature change larger than 15 ° C. occurs, the possibility that the electrode will be wrinkled due to thermal shrinkage increases.

  In the battery electrode manufacturing method described above, in the temperature equalization step, the temperature of the electrode is adjusted so that the temperature of the electrode falls within a range of ± 2 ° C. with respect to the space temperature of the weight measurement step. It is desirable to equalize.

  By doing in this way, the weight of an electrode can be measured more accurately using an ultrasonic wave, without using an ultrasonic sensor for temperature correction.

  And the manufacturing apparatus for implementing the above-described manufacturing method uses an ultrasonic sensor to dry the electrode mixture coated on the surface of the substrate, and the weight of the electrode dried in the drying furnace. In the battery electrode manufacturing apparatus having a weight measuring device for measuring, a temperature uniformizing device for uniformizing the temperature of the electrode to a desired temperature is provided between the drying furnace and the weight measuring device. And

  In the battery electrode manufacturing apparatus described above, it is preferable that the temperature equalizing apparatus includes a temperature adjusting roll that cools or raises the temperature of the electrode by contacting the electrode as an electrode transporting roll.

  Moreover, in the above-described battery electrode manufacturing apparatus, the temperature equalizing apparatus includes two or more rolls, and the temperature change of the electrodes due to contact with each roll is 15 ° C. or less. It is desirable to set each temperature.

  Further, in any one of the battery electrode manufacturing apparatuses described above, the temperature equalizing apparatus is configured so that the temperature of the electrode is within a range of ± 2 ° C. with respect to the space temperature in the weight measuring apparatus. It is desirable to make the temperature of the electrodes uniform.

  By having such a configuration, it is possible to accurately measure the weight of the electrode using ultrasonic waves without using an ultrasonic sensor for temperature correction. Moreover, it can also suppress that a wrinkle generate | occur | produces in an electrode by heat contraction.

  According to the method and apparatus for manufacturing a battery electrode according to the present invention, as described above, the weight of the electrode can be accurately measured using ultrasonic waves without correction.

It is a side view which shows schematic structure of an electrode. It is a schematic block diagram which shows the outline of an electrode manufacturing apparatus. It is a schematic block diagram which shows the outline of an ultrasonic sensor. It is a figure which shows the measurement result of the electrode temperature in a weight measuring apparatus. It is a figure which shows the result of having measured the weight of the electrode by a weight measuring apparatus. It is a figure which shows the result of having measured the weight of the electrode by a prior art.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a battery electrode manufacturing method and apparatus according to the present invention will be described below in detail with reference to the drawings. Here, the case where the electrode for lithium ion secondary batteries mounted in a vehicle is manufactured is illustrated.

  First, the electrode to be manufactured will be briefly described with reference to FIG. FIG. 1 is a side view showing a schematic configuration of an electrode plate. As shown in FIG. 1, the electrode 10 has an electrode mixture layer 21 formed on the surface of a band-shaped substrate (current collector) 20 (see FIG. 3). The electrode mixture layer 21 is bonded to the base material 20 by applying the electrode mixture to the base material 20 and then drying it. The electrode mixture is a conductive paste in which an active material, a conductive auxiliary material, a binder, a solvent, and the like are kneaded. In this embodiment, the thickness of the base material 20 is about 10 μm, and the thickness of the electrode mixture layer 21 is about 25 μm before drying and about 20 μm after drying.

  Here, there are two types of electrodes 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. Moreover, as an active material contained in the electrode mixture forming the electrode mixture layer 21 of the positive electrode, any material that occludes lithium ions during charging and releases lithium ions during discharging can be used. Examples thereof include lithium transition metal composite oxides such as lithium nickelate 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 of the lithium ion secondary battery. The active material contained in the electrode mixture forming the negative electrode mixture layer 21 may be any material that occludes lithium ions at the time of discharge and releases lithium ions at the time of charge. Examples thereof include carbon such as graphite, and amorphous amorphous carbon such as soft carbon and hard carbon.

  Here, although the material is different between the positive electrode and the negative electrode as described above, the width and thickness of the base material 20 and the electrode mixture layer 21 are basically the same. For this reason, the electrode manufacturing method and apparatus according to the present embodiment can be applied to either a positive electrode or a negative electrode of a lithium ion secondary battery. Therefore, below, it demonstrates as the electrode 10, without distinguishing especially a positive electrode and a negative electrode.

  Next, a manufacturing apparatus for manufacturing the above-described electrode 10 will be described with reference to FIG. FIG. 2 is a schematic configuration diagram showing an outline of the electrode manufacturing apparatus. The electrode manufacturing apparatus 30 includes an unwinding reel 40, a coating apparatus 50, a drying furnace 60 that performs a drying process, a temperature uniformizing apparatus 70 that performs a temperature uniformizing process, and a weight that performs a weight measuring process. A measuring device 80 and a take-up reel 90 are provided. In the electrode manufacturing apparatus 30, the electrode 10 is manufactured by performing the following steps in each apparatus on the base material 20 fed from the unwinding reel 40, and the manufactured electrode 10 is used as the winding reel 90. It is designed to be wound up by

  In the coating apparatus 50, a coating process for coating the electrode mixture on the surface of the substrate 20 is performed. In this coating step, the electrode mixture layer 21 is formed by applying the electrode mixture to the substrate 20 delivered from the unwinding reel 40. The coating device 50 is provided with a backup roll 51 and a die 52. The backup roll 51 is disposed at a position facing the die slit of the die 52 at a predetermined interval through which the substrate 20 can pass. Then, in a state where the base material 20 is sent out at a predetermined speed and supported by the outer peripheral surface of the backup roll 51, the electrode mixture supplied to the die 52 is discharged from the die slit at a constant flow rate, and is applied to the surface of the base material 20. Coated. Thereby, the electrode mixture having a predetermined thickness is applied to the surface of the base material 20 to form the electrode mixture layer 21.

  In the drying furnace 60, a drying process for drying the electrode mixture layer 21 formed on the surface of the substrate 20 is performed. In this drying step, the electrode mixture layer 21 on the substrate 20 passing through the drying furnace 60 is heated by hot air from a heating nozzle provided in the drying furnace 60, and the solvent is evaporated to form an electrode mixture layer. 21 is dried. At this time, the drying furnace 60 is controlled so as not to rapidly dry the electrode mixture layer 21. When the electrode mixture layer 21 is rapidly dried, the electrode mixture layer is cracked due to evaporation of the solvent contained in the electrode mixture, and the binder moves to the surface layer side and solidifies during drying. This is because segregation (migration) occurs in the mixture layer 21 and causes a problem.

  In the temperature equalizing apparatus 70, a temperature equalizing process is performed in which the temperature of the electrode 10 dried in the drying furnace 60 is equalized to a desired temperature. The temperature equalizing device 70 is provided with temperature adjusting rolls 71 and 72 that are in contact with the electrode 10 and adjust the temperature of the electrode 10 to a desired temperature (25 ° C. in the present embodiment). In the present embodiment, cooling rolls are used as the temperature adjustment rolls 71 and 72.

  The temperature adjustment rolls 71 and 72 are brought into contact with the electrode 10 to change the temperature of the electrode 10 stepwise to a desired temperature (25 ° C. in the present embodiment). At this time, the temperature of each of the rolls 71 and 72 is set so that the temperature change of the electrode 10 due to contact with each of the rolls 71 and 72 (temperature decrease in the present embodiment) is 15 ° C. or less. Further, the temperature adjusting rolls 71 and 72 are temperature controlled so that the temperature of the electrode 10 is within a range of ± 2 ° C. (23 to 27 ° C. in this embodiment) with respect to the space temperature of the weight measuring device 80. Has been done.

  Thereby, while the temperature change of the electrode 10 after drying is suppressed to 15 degrees C or less, the temperature of the electrode 10 can be reliably equalized to desired temperature. Moreover, it can also suppress that a wrinkle generate | occur | produces in the electrode 10 by heat contraction. Note that the temperature change of the electrode 10 due to contact with each of the rolls 71 and 72 is set to 15 ° C. or less. If a temperature change larger than 15 ° C. occurs in the electrode 10, wrinkles due to thermal contraction may occur in the electrode 10. This is because the sex becomes higher.

  In the weight measuring device 80, a weight measuring step of measuring the weight of the electrode 10 that has been uniformized to a desired temperature by the temperature uniformizing device 70 is performed. In this weight measurement step, the weight of the electrode 10 (the weight per unit area of the electrode 10 in the present embodiment) is calculated using ultrasonic waves. For this purpose, the weight measuring device 80 is provided with an ultrasonic sensor 81 as shown in FIG. FIG. 3 is a schematic configuration diagram showing an outline of the ultrasonic sensor.

  The ultrasonic sensor 81 is a pair of transmission type ultrasonic sensors including a transmission probe 81a and a reception probe 81b. The transmission probe 81a and the reception probe 81b are arranged so as to face each other with the electrode 10 being conveyed. The transmission probe 81a transmits an ultrasonic wave toward the electrode 10 and transmits through the electrode 10. When the reception probe 81b receives the ultrasonic wave (transmitted wave), the signal intensity with respect to the electrode 10 (the intensity of the ultrasonic signal transmitted toward the electrode 10 and transmitted through the electrode 10) is measured. Then, the weight measuring device 80 calculates the basis weight (corresponding to the thickness) of the electrode 10 according to the measured signal intensity.

  The transmission probe 81a and the reception probe 81b are configured so as to be integrally movable in the direction in which the electrode 10 extends (the width direction of the electrode 10) orthogonal to the direction in which the electrode 10 is conveyed. In addition, the electrode 10 is configured to reciprocate within a predetermined range with respect to the width direction of the electrode 10. Further, the ultrasonic frequency in the ultrasonic sensor 81 is a value that can be propagated in the air, and may be set to an optimum value (for example, 100 KHz or less) depending on the material of the electrode to be measured.

  Then, the method to manufacture the electrode 10 with the above-mentioned electrode manufacturing apparatus 30 is demonstrated. First, the electrode mixture is applied to the substrate 20 fed from the unwinding reel 40 by the coating device 50, and the electrode mixture layer 21 is formed on the surface of the substrate 20. The base material 20 on which the electrode mixture layer 21 is formed is dried in a drying furnace 60. Thus, the electrode 10 is obtained. Next, the temperature of the electrode 10 carried out of the drying furnace 60 is lowered stepwise by the temperature equalizing device 70 to be equalized to a desired temperature. Then, the weight measuring device 80 calculates the thickness of the electrode 10 at which the temperature is made uniform to the desired temperature.

Here, since the temperature of the electrode (base material) in the weight measuring apparatus 80 was measured, the measurement result is shown in FIG. FIG. 4 is a diagram showing the measurement result of the electrode temperature in the weight measuring apparatus. In addition, the broken line has shown the electrode temperature at the time of applying a prior art.
As apparent from FIG. 4, in the weight measuring device 80, it can be seen that the temperature of the electrode 10 is stable at a desired temperature (25 ° C. in the present embodiment). It can also be seen that the temperature of the electrode 10 is within ± 1 ° C. with respect to the desired temperature.

  Thus, in the weight measuring device 80, since the temperature of the electrode 10 is stable, it is not necessary to perform temperature correction as in the prior art when measuring the weight. Therefore, it is not necessary to separately provide an ultrasonic sensor for temperature correction. Thereby, it is not necessary to perform correction processing at the time of weight measurement. And the weight of the electrode 10 can be measured with high accuracy only by the ultrasonic sensor 81 without using the ultrasonic sensor for temperature correction.

Here, the measurement result of the weight of the electrode by the weight measuring apparatus 80 is shown in FIG. Note that the deviation amount shown in FIG. 5 is an error between the measured value and the measured value of the basis weight.
As is apparent from FIG. 5, the amount of deviation is almost zero. The measurement error is about 2% in the prior art, but can be reduced to about 0.2% in the present embodiment. That is, the measurement accuracy can be increased 10 times (error is 1/10).
As described above, since the influence of the electrode temperature on the weight measurement can be suppressed, the weight of the electrode 10 can always be accurately measured without being affected by a change in conditions in the drying process.

As described above in detail, in the present embodiment, the temperature at which the temperature of the electrode 10 is equalized to a desired temperature between the drying furnace 60 that performs the drying process and the weight measuring device 80 that performs the weight measuring process. Since the temperature equalizing device 70 for performing the homogenizing step is provided, the electrode temperature when the weight of the electrode 10 is measured by the weight measuring device 80 can be kept constant. As a result, the weight of the electrode 10 can be accurately measured using only the ultrasonic sensor 81 without using an ultrasonic sensor for temperature correction.
Moreover, since the influence on the weight measurement using the ultrasonic wave due to the temperature of the electrode 10 after drying can be suppressed, the weight of the electrode 10 is always kept without being affected by the condition change in the drying furnace 60. It can measure with high accuracy.

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, cooling rolls are used as the temperature adjustment rolls 71 and 72, but the temperature of the electrode 10 conveyed to the temperature uniformizing apparatus 70 depends on the manufacturing conditions and the like. When the temperature is lower than the space temperature, a heating roll may be used instead of the cooling roll.
In the above-described embodiment, two temperature adjusting rolls are provided in the temperature equalizing apparatus 70, but three or more temperature adjusting rolls may be provided.

DESCRIPTION OF SYMBOLS 10 Electrode 20 Base material 21 Electrode mixture layer 30 Electrode manufacturing apparatus 50 Coating apparatus 60 Drying furnace 70 Temperature equalization apparatus 71 Temperature adjustment roll 72 Temperature adjustment roll 80 Weight measuring apparatus 81 Ultrasonic sensor 81a Transmission probe 81b Reception probe Tentacle

Claims (5)

In a method for producing a battery electrode, comprising: a drying step of drying an electrode mixture coated on the surface of a substrate; and a weight measurement step of measuring the weight of the electrode dried in the drying step using ultrasonic waves. ,
A method for producing a battery electrode, comprising: a temperature equalizing step for equalizing a temperature of the electrode to a desired temperature between the drying step and the weight measuring step. In the manufacturing method of the battery electrode according to claim 1,
In the temperature equalizing step, a temperature adjusting roll that cools or raises the temperature of the electrode by contacting the electrode is used as an electrode transporting roll, and the temperature of the electrode is made uniform. Manufacturing method. In the manufacturing method of the battery electrode according to claim 2,
In the temperature equalization step, two or more temperature adjustment rolls are arranged, and the temperature of each roll is set so that the temperature change of the electrode due to contact with each roll is 15 ° C. or less. A method for producing a battery electrode. In the manufacturing method of any one battery electrode as described in any one of Claims 1-3,
In the temperature homogenization step, the temperature of the electrode is made uniform so that the temperature of the electrode falls within a range of ± 2 ° C. with respect to the space temperature of the weight measurement step. Manufacturing method. A battery electrode manufacturing apparatus comprising: a drying furnace for drying an electrode mixture coated on a surface of a substrate; and a weight measuring device for measuring the weight of the electrode dried in the drying furnace using an ultrasonic sensor. In
An apparatus for manufacturing a battery electrode, comprising: a temperature uniformizing device for uniformizing a temperature of the electrode to a desired temperature between the drying furnace and the weight measuring device.

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