JP2018142443A - Inspection method for electrode, and inspection device for electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection device for an electrode capable of accurately inspecting a formation state of a coating part of a coating layer material.SOLUTION: An inspection method for a negative electrode includes a detection step, a measurement step and a discrimination step. In the detection step, a belt-like electrode 19 comprising a metal foil 11 in a long belt shape, an anode active material layer 12 existing on both surfaces of a metal foil 11 and a coating part 18 that is a precursor of a protection layer formed by coating a surface of the anode active material layer 12 with a ceramic slurry is conveyed in a length direction. With respect to a spot of the belt-like electrode 19 where the belt-like electrode is conveyed while being supported in such a manner that a side view of the belt-like electrode in a length direction becomes arcuate, a fluorescent X-ray detection device 41 is oscillated in a width direction of the belt-like electrode 19 with a center C of a circular arc L defined as an axis, and a fluorescent X ray generated from the belt-like electrode 19 is detected. In the measurement step, an energy strength of aluminum contained in the coating part 18 of the belt-like electrode 19 is measured from the detected fluorescent X ray. In the discrimination step, based on the energy strength, the quality of a formation state of the coating part 18 in the belt-like electrode 19 is discriminated.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electrode inspection method and inspection apparatus having a current collector, an active material layer present on both or one side of the current collector, and a coating layer present on the surface of the active material layer.

  As an example of an electrode used for a secondary battery as a power storage device, a metal foil as a current collector, an active material layer present on both surfaces or one surface of the metal foil, and a coating layer present on the surface of the active material layer An electrode having a protective layer is known (see, for example, Patent Document 1). In the electrode having such a configuration, it is necessary to inspect whether or not the formation state of the coating portion of the protective layer material as the coating layer material is good. In Patent Document 1, fluorescent X-rays generated from a metal foil on which an active material layer and a protective layer material coating part are formed are measured, and the thickness (weight per unit area) of the protective layer material coating part is determined from the measurement result. Acquired and inspected whether the formation state of the coated part is good.

JP 2009-193906 A

In the inspection of the formation state of such a coating part, a highly accurate inspection is desired.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electrode inspection method and an electrode inspection apparatus that can accurately inspect the formation state of the coating portion of the coating layer material. It is in.

  An electrode inspection method that solves the above problem is an electrode inspection method that includes a current collector, an active material layer that is present on both or one side of the current collector, and a coating layer that covers the surface of the active material layer. The elongated strip-shaped current collector, the active material layer existing on both sides or one side of the elongated strip-shaped current collector, and a coating layer material applied to the surface of the active material layer were formed. A belt-shaped electrode having a coating portion that is a precursor of the coating layer is transported in the longitudinal direction, and is transported in a state where the strip-shaped electrode viewed from the longitudinal direction is supported so that a side view is an arc. On the other hand, the fluorescent X-ray detection device is swung in the short direction of the strip electrode with the center of the arc as an axis to detect the fluorescent X-ray generated from the strip electrode, and from the fluorescent X-ray, A measuring process for measuring the energy intensity of the elements contained in the coated part of the strip electrode, Based on the energy intensity is summarized in that comprising a determination step of determining the quality of the formation state of the coated portion of the strip electrodes.

  According to this, since the distance between the strip electrode application portion and the fluorescent X-ray detection device can be made constant in the detection step, variation in detection results is suppressed, and quantitative detection of fluorescent X-rays becomes possible. Therefore, the formation state of the coating part of coating layer material can be test | inspected accurately.

Moreover, about the inspection method of an electrode, it is preferable to include the gas injection process which injects gas toward the coating part of the said strip | belt-shaped electrode in the middle of the said detection process.
According to this, since the atmosphere between the coating part of the belt-like electrode and the fluorescent X-ray detection device can be kept constant, the variation in detection results is suppressed. Therefore, the formation state of the coating part of coating layer material can be test | inspected accurately. Further, since the belt-like electrode is supported in an arc shape, the gas inside the arc does not easily escape, and the atmosphere is more easily maintained.

Moreover, about the inspection method of an electrode, it is preferable that the said gas injection process also serves as a part of drying process which dries the coating part of the said strip electrode.
The inspection of the electrode is performed during the production of the electrode by applying the coating layer material. Since the drying of the coating layer material is promoted by injecting gas in order to keep the atmosphere between the coating portion of the strip electrode and the fluorescent X-ray detection device constant, while checking the formation state of the coating portion The productivity of the strip electrode on which the coating part is formed can be improved. In addition, when a high-temperature gas is used, since the strip electrode is supported in an arc shape, the temperature of the gas inside the arc is not easily lowered, and the coating part can be dried more effectively. .

In the electrode inspection method, it is preferable that the fluorescent X-ray detection device is continuously swung in the detection step.
According to this, the coating part of the coating layer material of the strip electrode can be inspected in the entire longitudinal direction and the short direction.

Moreover, about the inspection method of an electrode, it is preferable that the said coating layer is a protective layer which protects the said active material layer.
According to this, the coating state of the protective layer material can be accurately inspected. Since the protective layer has an insulating function to insulate between the electrodes when a plurality of electrodes having an active material layer are stacked, it is important to inspect the coating state of the protective layer material.

Regarding the electrode inspection method, the element whose energy intensity is measured in the measurement step is preferably a light element having an atomic number of 3 to 20.
According to this, the coating of the protective layer material is performed by the energy intensity of fluorescent X-rays emitted from a light element having an atomic number of 3 or more that can generate the main component of the protective layer material and an atomic number of 20 or less that does not decrease the weight energy density of the electrode. The formation state of the working part can be inspected.

Regarding the electrode inspection method, the electrode is preferably a negative electrode, and the light element is preferably aluminum.
Generally, since the protective layer is often formed on the negative electrode and often contains aluminum, the protective layer material applied to the negative electrode is formed by the energy intensity of fluorescent X-rays emitted from aluminum. The formation state can be inspected.

  An electrode inspection apparatus that solves the above-described problems is an electrode inspection apparatus that includes a current collector, an active material layer that is present on one or both surfaces of the current collector, and a coating layer that covers the surface of the active material layer. A long strip-shaped current collector, an active material layer covering both surfaces or one surface of the long strip-shaped current collector, and a coating layer material applied to the surface of the active material layer. From a conveying device that conveys a strip electrode having a coating portion that is a precursor of a coating layer in the longitudinal direction, a fluorescent X-ray detection device that detects fluorescent X-rays generated from the strip electrode, and the fluorescent X-ray, A measurement unit that measures the energy intensity of an element contained in the coating part of the strip electrode, and a determination device that determines the quality of the formation state of the coating part of the strip electrode based on the energy intensity, The transport device includes a support member that supports the belt-like electrode, and the support member And a support concave portion having an arc shape in a side view when the belt-like electrode is viewed from the longitudinal direction, and the X-ray fluorescence detector is arranged in a short direction of the belt-like electrode with the center of the arc of the support concave portion as an axis. The gist is that it can swing.

  According to this, since the distance between the coating portion of the strip-shaped electrode supported in an arc shape and the fluorescent X-ray detection device can be made constant, variations in detection results are suppressed, and quantitative detection of fluorescent X-rays is possible. It becomes. Therefore, the formation state of the coating part of coating layer material can be test | inspected accurately.

In addition, the electrode inspection apparatus preferably includes a gas injection device that injects gas toward a portion where the fluorescent X-ray is detected in the coating portion of the strip electrode.
According to this, since the atmosphere between the coating part of the belt-like electrode and the fluorescent X-ray detection device can be kept constant, the variation in detection results is suppressed. Therefore, the formation state of the coating part of coating layer material can be test | inspected accurately. In addition, since the support concave portion supports the belt-like electrode in an arc shape, the gas inside the arc does not easily escape and the atmosphere is more easily maintained.

  ADVANTAGE OF THE INVENTION According to this invention, the formation state of the coating part of coating layer material can be test | inspected accurately.

The perspective view of an electrode. The schematic side view which shows a protective layer formation process. The schematic sectional drawing which shows the detection process in a protective layer formation process. The perspective view which shows the detection process in a protective layer formation process. The perspective view which shows the supporting member of the conveying apparatus of another example.

Hereinafter, an embodiment in which an electrode inspection method is embodied as an electrode inspection method for a secondary battery will be described with reference to FIGS.
Although not shown, a secondary battery as a power storage device using an electrode to be inspected by the inspection method of this embodiment is a square battery having a rectangular external appearance, and is a lithium ion secondary battery. This secondary battery includes an electrode assembly in a case. The electrode assembly includes a plurality of positive electrodes as electrodes and a plurality of negative electrodes. The electrode assembly is configured by alternately laminating positive electrodes and negative electrodes in a state where they are insulated by a separator. Hereinafter, the electrode to be inspected is embodied as a negative electrode, and the configuration and the inspection method will be described.

  As shown in FIG. 1, a negative electrode 10 for a secondary battery includes a rectangular metal foil 11 as a current collector and a negative electrode active material layer 12 as an active material layer present on both surfaces of the metal foil 11. Prepare. The metal foil 11 is made of a metal (for example, copper) that does not contain aluminum as an element used for later inspection. The negative electrode 10 has an uncoated portion 13 along which the negative electrode active material layer 12 is not present and the metal foil 11 is exposed. And in the negative electrode 10, the current collection tab 14 exists in the state which protrudes in a part of uncoated part 13. FIG. The negative electrode 10 includes a protective layer 15 as a coating layer that covers the entire surface of the negative electrode active material layer 12. The protective layer 15 has an insulating function for insulating the positive electrode and the negative electrode 10. The protective layer 15 includes alumina particles as ceramic particles and a resin binder, and the alumina particles or the alumina particles and the active material particles on the surface of the negative electrode active material layer 12 are bonded via the binder to form a layer structure. Have. The heat-resistant temperature of the protective layer 15 mainly composed of alumina particles is higher than that of a resin separator. Moreover, since the protective layer 15 has alumina particles as a main component, it contains aluminum which is a light element among the elements as a main component.

  Next, the manufacturing process of the negative electrode 10 will be described. The manufacturing process of the negative electrode 10 includes an active material layer forming process in which the negative electrode active material layer 12 is formed on both surfaces of the long metal foil 11, and a coating layer forming in which the protective layer 15 is formed on the surface of the negative electrode active material layer 12. A protective layer forming step as a step and a cutting step of cutting the metal foil 11 on which the negative electrode active material layer 12 and the protective layer 15 are formed into the shape of the negative electrode 10 are included.

  Although not shown, the active material layer forming step includes a coating step, a drying step, and a pressing step. The application step is a step of applying an active material paste to one side of the long strip-shaped metal foil 11. However, the active material paste is not applied to the portion that will later become the uncoated portion 13. The drying step is a step of drying the coated active material paste to form a negative electrode active material layer precursor. A press process is a process of raising the active material density of a negative electrode active material layer precursor by letting the metal foil 11 in which the negative electrode active material layer precursor was formed pass a roll press machine after a drying process. Thereby, the negative electrode active material layer 12 having a predetermined density and thickness is formed on one surface of the strip-shaped metal foil 11. Similarly, the negative electrode active material layer 12 is formed on the other surface of the metal foil 11. In the active material layer forming step, the long strip-shaped metal foil 11 having the negative electrode active material layer 12 formed on both surfaces becomes the electrode material 16. Hereinafter, a direction perpendicular to the longitudinal direction of the electrode material 16 and along the surface of the electrode material 16 is defined as a short direction.

  As shown in FIG. 2, the protective layer forming process includes a coating process, an inspection process, and a drying process. In the coating process, while conveying the electrode material 16 in the longitudinal direction, a ceramic slurry 17 that is a protective layer material as a coating layer material is applied to the surface of the negative electrode active material layer 12 of the electrode material 16, This is a step of forming the coating portion 18 to be a precursor. Therefore, the coating part 18 is formed by the coating of the ceramic slurry 17. The inspection step is a step of inspecting the formation state of the coating part 18 formed in the coating step.

  The transport device 20 used in the protective layer forming step includes a supply reel 21, a take-up reel 22, a plurality of guide rolls 23, and a transport roll 24 as a support member. The supply reel 21 is disposed at a location upstream of the coating process, and the take-up reel 22 is disposed at a location downstream of the drying process. The guide roll 23 is disposed at a location between the supply reel 21 and the take-up reel 22. The supply reel 21, the take-up reel 22, and the guide roll 23 are rotatably supported by a support device (not shown). The electrode material 16 is wound around the supply reel 21. The electrode material 16 supplied from the supply reel 21 is taken up by the take-up reel 22.

  As shown in FIG. 4, the transport roll 24 is arranged in the inspection process. The transport roll 24 is rotatably supported by a support device (not shown). The transport roll 24 has a support recess 24a that exists over the entire circumference. The support recess 24a is configured such that the diameter of the transport roll 24 decreases in a curved manner from both ends in the rotation axis direction to the center. The support recesses 24 a are on the inner side than both ends of the transport roll 24 in the rotation axis direction. In the side view as seen from the longitudinal direction of the electrode material 16, the support recess 24a has an arc shape. A surface lubricant may or may not be applied by applying a solid lubricant or the like to the surface of the recess 61a. The center of the arc L of the support recess 24a is defined as the center C. When the electrode material 16 is supported by the transport roll 24, the electrode material 16 is supported in a state of being deformed in an arc shape along the support recess 24a. Moreover, the electrode material 16 is conveyed in a longitudinal direction by the conveyance roll 24 rotating.

  The coating apparatus that performs the coating process is a gravure coating apparatus 30. The gravure coating apparatus 30 includes a storage portion 31 for the ceramic slurry 17, a cylindrical gravure roll 32, and a back roll 33 that faces the gravure roll 32 and the electrode material 16. The ceramic slurry 17 stored in the storage unit 31 is obtained by kneading alumina particles and a binder such as PVDF (polyvinylidene fluoride) with water or a nonaqueous solvent such as NMP (N methylpyrrolidone). The concentration of alumina particles contained in the ceramic slurry 17 is made uniform.

  Although not shown, an oblique gravure pattern is engraved on the outer peripheral surface of the gravure roll 32. For this reason, the gravure roll 32 has the groove | channel 32a extended diagonally with respect to an axial direction. Further, the gravure roll 32 is supported in a state where a part of the outer peripheral surface is always exposed in the storage portion 31.

  Such a gravure roll 32 is rotationally driven by a motor 34. A controller 35 is connected to the motor 34. The rotation speed of the motor 34 is controlled by the control device 35. As the gravure roll 32 rotates, the ceramic slurry 17 in the reservoir 31 adheres to the surface of the gravure pattern while entering the groove 32a of the gravure roll 32. The ceramic slurry 17 adhering to the surface of the gravure pattern is conveyed toward the electrode material 16 from the storage unit 31 by the rotation of the gravure roll 32. At the coating position P, the conveyed ceramic slurry 17 contacts the surface of the negative electrode active material layer 12 of the electrode material 16 supplied from the supply reel 21. As a result, the ceramic slurry 17 is applied to the surface of the negative electrode active material layer 12 to form a coating portion 18. As described above, since the concentration of alumina particles in the ceramic slurry 17 is constant, the concentration of aluminum in the coating part 18 is also constant. The electrode material 16 on which the coating part 18 is formed becomes a strip electrode 19.

  In the inspection process, a negative electrode inspection device 40 as an electrode inspection device is used. The inspection device 40 includes a fluorescent X-ray detection device 41, a gas injection device 44, a measurement device 45, and a determination device 48 which will be described later.

  The inspection step includes a detection step of detecting fluorescent X-rays β generated from the strip electrode 19 while transporting the strip electrode 19 in the longitudinal direction. The detection process is performed using the fluorescent X-ray detection device 41 of the inspection device 40. The X-ray fluorescence detector 41 is disposed above the support recess 24 a of the transport roll 24. In this embodiment, as a fluorescent X-ray detector 41, a Oxford handheld metal material discriminator (model: X-MET8000, X-ray tube: voltage 50 kV, rhodium target, detector: silicon drift type) is used. However, it is not limited to this.

  As shown in FIGS. 2 and 3, the X-ray fluorescence detection apparatus 41 has an integrated X-ray tube 42 capable of emitting primary X-rays α and a detection unit 43 capable of detecting fluorescence X-rays β. Device. The X-ray tube 42 irradiates the primary X-ray α on the irradiation range Q on the strip electrode 19 (for example, a rectangular range extending 5 mm in the longitudinal direction and 5 mm in the short direction) (see FIG. 4). Then, in the irradiation range Q of the primary X-ray α, the atoms of the portion constituting the thickness of the strip electrode 19 are in an excited state, and fluorescent X-rays β are generated when returning from the excited state to the stable state. The detection unit 43 detects this fluorescent X-ray β.

  The X-ray fluorescence detector 41 can swing in the short direction of the strip electrode 19 with the center C of the arc L of the support recess 24a as the swing axis. Further, as described above, the strip electrode 19 is conveyed in a state of being supported along the arc L by the support recess 24a in a side view as viewed from the longitudinal direction. For this reason, the distance X between the fluorescent X-ray detector 41 and the strip electrode 19 is always constant. In addition, the X-ray fluorescence detection apparatus 41 of the present embodiment continuously swings from one end (the other end) to the other end (one end) in the short direction of the strip electrode 19 and is short on the strip electrode 19. X-rays β generated from the strip electrode 19 are detected for a plurality of irradiation ranges Q (for example, first to fifth irradiation ranges Q1 to Q5) existing at different positions. Therefore, the fluorescent X-ray detection device 41 inspects the whole of the strip electrode 19 in the longitudinal direction and the lateral direction. Then, the detection unit 43 outputs the detection result of the fluorescent X-rays β generated in the first to fifth irradiation ranges Q1 to Q5 of the strip electrode 19 to the measurement device 45.

  By the way, the detection unit 43 detects fluorescent X-rays β of a plurality of elements included in the strip electrode 19. The fluorescent X-ray β has a unique energy that is different for each element. For example, since the metal foil 11 is made of copper, the detection unit 43 detects the fluorescent X-ray β having energy specific to copper. Further, since the coating unit 18 includes alumina particles (aluminum), the detection unit 43 detects fluorescent X-rays β having energy specific to aluminum. Further, the energy intensity of the fluorescent X-ray β of each element is determined by the amount of atoms contained in the portion constituting the thickness of the strip electrode 19 in the irradiation range Q. The detection result of the fluorescent X-ray β output from the detection unit 43 to the measurement device 45 includes the energy intensity of a plurality of elements included in the strip electrode 19.

  The inspection process includes a gas injection process for injecting gas toward the coating portion 18 of the strip electrode 19. The gas injection process is performed during the detection process. The gas injection process is performed using the gas injection device 44 of the inspection device 40. In addition, illustration of the gas injection apparatus 44 is abbreviate | omitted in FIG.

  The gas injection device 44 of this embodiment is attached to both ends of the fluorescent X-ray detection device 41 in the short direction of the strip electrode 19 and is integrated with the fluorescent X-ray detection device 41. The gas injection device 44 oscillates in the short direction of the strip electrode 19 as the fluorescent X-ray detection device 41 oscillates, and injects gas toward the irradiation range Q. As a result, the gas fills the inside of the support recess 24 a of the transport roll 24, that is, the coating portion 18 of the strip electrode 19. The gas used in the gas injection process is, for example, an inert gas such as argon, and the temperature and humidity of the gas are set higher and higher than the coating unit 18. Moreover, drying of the coating part 18 can be accelerated | stimulated with this gas. However, since the coating unit 18 cannot be completely dried in the gas injection process, the coating unit 18 needs to be further dried by a drying device 50 described later. The gas injection process also serves as a part of the drying process for drying the coating part 18.

  The inspection step includes a measurement step of measuring the energy intensity of aluminum contained in the strip electrode 19 from the detection result in the detection step. The measurement process is performed using the measurement device 45 of the inspection device 40. The measuring device 45 is signal-connected to the fluorescent X-ray detection device 41.

  The measuring device 45 includes a measuring unit 46 that measures the energy intensity of aluminum. A detection result for the strip electrode 19 is input from the detection unit 43 to the measurement unit 46. The measurement part 46 measures the energy intensity of the aluminum contained in the strip electrode 19 for the first to fifth irradiation ranges Q1 to Q5, respectively, and sets each measurement value as the first to fifth inspection values A1 to A5. Moreover, the measurement part 46 measures energy intensity, whenever a detection result is output from the detection part 43, and updates 1st-5th test value A1-A5.

  The inspection step includes a comparison step of comparing each inspection value A1 to A5 with the upper limit value AH and the lower limit value AL of the energy intensity. The comparison process is performed using the comparison unit 47 of the measurement device 45. The first to fifth inspection values A1 to A5 are input from the measurement unit 46 to the comparison unit 47. The upper limit value AH and the lower limit value AL are aluminum energy strengths set in advance corresponding to the upper limit and the lower limit of the basis weight of the coating unit 18, and are stored in the comparison unit 47.

  The comparison unit 47 compares the first inspection value A1 with the upper limit value AH. The comparison unit 47 generates a signal S1 when the first inspection value A1 is larger than the upper limit value AH, and generates a signal S2 when the first inspection value A1 is equal to or lower than the upper limit value AH. The comparison unit 47 compares the first inspection value A1 with the lower limit value AL. The comparison unit 47 generates a signal S3 when the first inspection value A1 is greater than or equal to the lower limit value AL, and generates a signal S4 when the first inspection value A1 is smaller than the lower limit value AL. The comparison unit 47 similarly compares the second to fifth inspection values A2 to A5, and generates signals S1 to S4.

  The inspection process includes a determination process for determining whether the formation state of the coating part 18 of the strip electrode 19 is good or not based on the signals S1 to S4 generated by the comparison part 47. The determination process is performed by the determination device 48 of the inspection device 40. The determination device 48 is signal-connected to the measurement device 45. Signals S <b> 1 to S <b> 4 are input from the comparison unit 47 to the determination device 48. The determination device 48 is connected to the control device 35 of the motor 34 of the gravure coating device 30.

  When the signals S2 and S3 are input from the comparator 47 for the first inspection value A1, that is, when the first inspection value A1 is equal to or lower than the upper limit value AH and equal to or higher than the lower limit value AL, the determination device 48 determines the first irradiation range Q1. The formation state of the coating part 18 is determined to be good (the basis weight is within the target range). When the signal S1 is input from the comparison unit 47 for the first inspection value A1, that is, when the first inspection value A1 is larger than the upper limit value AH, the determination device 48 forms the coating unit 18 in the first irradiation range Q1. The state is determined to be defective 1 (the basis weight is outside the target range). When the signal S4 is input from the comparison unit 47 for the first inspection value A1, that is, when the first inspection value A1 is smaller than the lower limit value AL, the determination device 48 forms the coating unit 18 in the first irradiation range Q1. The state is determined to be defective 2 (the basis weight is outside the target range). The determination device 48 performs the same determination on the second to fifth inspection values A2 to A5.

  Further, when the determination device 48 determines that three or more of the coating portions 18 in the first to fifth irradiation ranges Q1 to Q5 are defective 1, a signal of “overweight per unit weight” is sent to the control device 35. Is output. When the determination device 48 determines that three or more of the coating portions 18 in the first to fifth irradiation ranges Q1 to Q5 are defective 2, the controller 48 outputs a signal of “insufficient basis weight” to the control device 35. To do. When the “overweight basis weight” signal is input, the control device 35 accelerates the rotational drive of the motor 34 to accelerate the rotation speed of the gravure roll 32 and reduces the basis weight of the coating unit 18. On the other hand, when a signal of “insufficient basis weight” is input, the control device 35 reduces the rotational speed of the gravure roll 32 by reducing the rotational drive of the motor 34 and increases the basis weight of the coating unit 18.

  After the inspection process, the strip electrode 19 is conveyed into the drying device 50. The drying device 50 completely dries the coating part 18 in a state where the drying has progressed by the gas in the gas injection process. The coating part 18 becomes a protective layer precursor. The strip electrode 19 on which the protective layer precursor is formed is cut into the shape of the negative electrode 10 in a cutting step (not shown). A protective layer 15 is formed from the protective layer precursor. In this way, the sheet-like negative electrode 10 is manufactured.

Next, the operation of this embodiment will be described.
In the detection step of the protective layer forming step, the fluorescent X-rays β generated from the strip electrode 19 are detected by the fluorescent X-ray detection device 41 while the strip electrode 19 is transported in the longitudinal direction by the transport device 20. At this time, a part of the belt-like electrode 19 is transported while being supported in an arc shape by the support recess 24a of the transport roll 24 in a side view as viewed from the longitudinal direction. The fluorescent X-ray detection apparatus 41 swings in the short direction of the strip electrode 19 with the center C of the arc L of the support recess 24a as the swing axis. For this reason, the distance X between the coating part 18 of the strip electrode 19 and the fluorescent X-ray detector 41 is kept constant, and the fluorescent X-ray β can be quantitatively detected.

Next, the effect of this embodiment will be described.
(1) In the detection step, a part of the strip electrode 19 is transported in the longitudinal direction while being supported in an arc shape by the support recess 24a of the transport roll 24 in a side view as viewed from the longitudinal direction. The X-ray fluorescence detector 41 that detects the fluorescent X-rays β generated from the strip electrode 19 swings in the short direction of the strip electrode 19 with the center C of the arc L of the support recess 24a as the swing axis. For this reason, the distance X between the coating part 18 of the strip electrode 19 and the fluorescent X-ray detection device 41 in the detection step is kept constant. Therefore, variation in the detection result of the fluorescent X-ray β is suppressed, the fluorescent X-ray β can be quantitatively detected, and the formation state of the coating portion 18 can be inspected with high accuracy.

  (2) Since the detection step includes a gas injection step of injecting gas toward the coating portion 18 of the strip electrode 19 during the detection step, the coating portion 18 of the strip electrode 19 and the fluorescent X-ray detection device 41 is kept constant, and variations in detection results are suppressed. Therefore, the formation state of the coating part 18 can be inspected with high accuracy. Further, since the belt-like electrode 19 is supported in an arc shape by the support recess 24a, the gas inside the arc L is difficult to escape, and the atmosphere is more easily maintained.

(3) Since the gas used in the gas injection process is an inert gas, the scattering of the fluorescent X-ray β by the atmosphere is suppressed, and the formation state of the coating part 18 can be inspected with higher accuracy.
(4) Since the fluorescent X-ray detection device 41 is continuously swung, the coating portion 18 of the strip electrode 19 can be inspected over the entire length direction and the short direction.

(5) The formation state of the coating part 18 can be inspected by the energy intensity of the fluorescent X-ray β emitted from aluminum which is a light element.
(6) The gas injection process also serves as a part of the drying process. For this reason, drying of the coating part 18 is accelerated | stimulated with the gas in a gas injection process, and the drying time by the drying apparatus 50 can be shortened. Even when a high-temperature gas is used, the belt-like electrode 19 is supported in an arc shape by the support recess 24a, so that the temperature of the gas inside the arc L is less likely to be lowered, and the coating portion 18 is further dried. Can be done effectively.

(7) Since the gas injection device 44 swings together with the fluorescent X-ray detection device 41, the gas injection device 44 can inject gas toward the irradiation range Q in the coating portion 18 of the strip electrode 19.
In addition, you may change the said embodiment as follows.

  The negative electrode 10 may have the negative electrode active material layer 12 and the protective layer 15 only on one side of the metal foil 11. In this case, the negative electrode active material layer 12 is provided only on one surface of the belt-like electrode 19, and the coating portion 18 of the ceramic slurry 17 is formed on the negative electrode active material layer 12.

The current collector is not limited to the metal foil 11 as long as the negative electrode active material layer 12 can be formed. For example, a woven or net-like sheet may be used.
O The element whose energy intensity is measured in the measurement process is not limited to aluminum, but may be other elements. For example, a light element having an atomic number of 3 or more that can generate ceramic particles and an atomic number of 20 or less that does not decrease the weight energy density of the negative electrode 10 may be used.

  In the above embodiment, the ceramic particles included in the protective layer 15 are alumina particles, but may be aluminum nitride. Moreover, when the negative electrode active material layer 12 does not contain silicon (silicon), the ceramic particles included in the protective layer 15 may be oxides or nitrides of other elements such as silicon dioxide and silicon nitride.

  The coating layer may be an active material layer different from the negative electrode active material layer 12 present on both surfaces of the metal foil 11. However, elements included in the negative electrode active material layer 12 present on both surfaces of the metal foil 11 and elements included in another negative electrode active material layer covering the negative electrode active material layer 12 and whose energy intensity is measured in the measurement step are , Make another element.

  In the above embodiment, the inspection method and the inspection apparatus 40 for the negative electrode 10 are described in detail, but the positive electrode can also be inspected by the same inspection method and inspection apparatus. However, the element constituting the current collector of the positive electrode and the element which is included in the protective layer of the positive electrode and whose energy intensity is measured in the measurement process are different elements.

  The active material paste coating step in the active material layer forming step may be continuous coating performed continuously in the longitudinal direction of the long strip-shaped metal foil 11 or intermittent coating applied at intervals. In the case of intermittent coating, the coating process of the ceramic slurry 17 in the protective layer forming process is performed by intermittently stopping the rotation of the gravure roll 32 and coating the electrode material 16 at intervals in the longitudinal direction. can do.

The support member for supporting the strip electrode 19 in an arc shape when viewed from the longitudinal direction is not limited to the transport roll 24 of the above embodiment.
For example, as shown in FIG. 5, instead of the transport roll 24, a support portion 61 having an arcuate recess 61 a that supports the strip electrode 19 may be used as a support member. The support part 61 is fixed by a support device (not shown). In this case, the belt-like electrode 19 is conveyed in the longitudinal direction by being wound from the supply reel 21 to the take-up reel 22. A surface lubricant may or may not be applied by applying a solid lubricant or the like to the surface of the recess 61a.

The strip electrode 19 may be supported in an arc shape by the support recess 24a not only in the detection step but also in a subsequent step (in the embodiment, a drying step) that is continuous with the detection step.
The range in which the fluorescent X-ray detection device 41 is swung may be changed as appropriate, for example, according to the width of the coating unit 18 in the short direction.

In the above embodiment, the fluorescent X-ray detection device 41 is continuously swung, but may be swung intermittently.
O Although the detection process was performed before the drying process, it may be performed after the drying process.

○ The gas injection step may be omitted.
○ Depending on the temperature and humidity of the gas in the gas injection process, the gas injection process may be part of the drying process.

  The number of gas injection devices 44 may be changed as appropriate. Further, the gas injection device 44 may be separate from the fluorescent X-ray detection device 41. In this case, the gas injection device 44 may be swung or fixed.

  ○ As the inert gas used in the gas injection step, nitrogen or carbon dioxide may be used in addition to argon. Moreover, the gas used for a gas injection process is not limited to an inert gas, Air may be sufficient. Moreover, you may change suitably the temperature and humidity of the gas used for a gas injection process. When the temperature and humidity of the gas are higher than the temperature and humidity of the coating unit 18, the coating unit 18 can be dried.

The X-ray fluorescence detection device 41 and the measurement device 45 may be integrated or separated.
In the above embodiment, while the X-ray fluorescence detector 41 swings from one end (other end) to the other end (one end) in the short direction of the strip electrode 19, the five irradiation ranges Q1 on the strip electrode 19 Although the detection is performed in Q5, the number of irradiation ranges Q may be changed as appropriate.

  In the above embodiment, the energy intensity of aluminum contained in the strip electrode 19 is measured for each irradiation range Q1 to Q5, and the measured values are set as the first to fifth inspection values A1 to A5. You may take the average of a measured value about the 5th irradiation range Q1-Q5, and may set the average value of energy intensity as one inspection value.

The condition for the determination device 48 to output a signal of “excess basis weight” or “underweight basis weight” to the control device 35 may be changed as appropriate.
○ In the above-described embodiment, the pass / fail judgment of the formation state of the coating part 18 is utilized by feeding back to the coating process. However, for the selection of non-defective / defective products of the negative electrode 10 on which the protective layer 15 is formed. It may be used.

In the above embodiment, the active material layer forming step, the protective layer forming step, and the cutting step are performed in separate production lines, but may be performed continuously in the same production line.
(Circle) You may apply to the inspection method of the electrode for not only the electrode inspection method for laminated | stacked electrode assemblies but the winding type electrode assembly.

  The electrode inspection method in the above embodiment may be applied to, for example, an electrode inspection method for electrodes used in nickel hydride secondary batteries and power storage devices such as lithium capacitors.

  DESCRIPTION OF SYMBOLS 10 ... Negative electrode as an electrode, 11 ... Metal foil as a collector, 12 ... Negative electrode active material layer as an active material layer, 15 ... Protective layer as a coating layer, 17 ... Ceramic slurry as a coating layer material, 18 DESCRIPTION OF SYMBOLS ... Coating part, 19 ... Strip electrode, 20 ... Conveyance device, 24 ... Conveyance roll as support member, 24a ... Support recessed part, 40 ... Inspection apparatus, 41 ... Fluorescence X-ray detection apparatus, 44 ... Gas injection apparatus, 46 ... Measurement unit, 48: determination device, L: arc, β: fluorescent X-ray.

Claims (9)

An inspection method for an electrode comprising a current collector, an active material layer present on both or one side of the current collector, and a coating layer covering the surface of the active material layer,
A long strip current collector, an active material layer present on both or one side of the long strip current collector, and the coating layer formed by coating a coating layer material on the surface of the active material layer A belt-like electrode having a coating part that is a precursor of the material is conveyed in the longitudinal direction, and the portion of the belt-like electrode viewed from the longitudinal direction is supported so that the side view is an arc. A detection step of detecting an X-ray fluorescence generated from the strip electrode by swinging an X-ray detection device in the short direction of the strip electrode with the center of the arc as an axis;
From the fluorescent X-ray, a measurement step of measuring the energy intensity of the element contained in the coating part of the strip electrode,
And a determination step of determining whether or not the formation state of the coating portion of the strip electrode is based on the energy intensity.   The electrode inspection method according to claim 1, further comprising a gas injection step of injecting a gas toward the coating portion of the strip electrode during the detection step.   The electrode inspection method according to claim 2, wherein the gas injection step also serves as a part of a drying step of drying a coating portion of the strip electrode.   The electrode inspection method according to claim 1, wherein in the detection step, the fluorescent X-ray detection device is continuously swung.   The said coating layer is a protective layer which protects the said active material layer, The inspection method of the electrode as described in any one of Claims 1-4.   6. The electrode inspection method according to claim 5, wherein the element whose energy intensity is measured in the measuring step is a light element having an atomic number of 3 to 20. The electrode is a negative electrode;
The electrode inspection method according to claim 6, wherein the light element is aluminum. An inspection apparatus for an electrode having a current collector, an active material layer present on both or one side of the current collector, and a coating layer covering the surface of the active material layer,
A long strip current collector, an active material layer present on both or one side of the long strip current collector, and the coating layer formed by coating a coating layer material on the surface of the active material layer A transport device for transporting in the longitudinal direction a strip electrode having a coating part which is a precursor of
A fluorescent X-ray detector for detecting fluorescent X-rays generated from the strip electrode;
From the fluorescent X-ray, a measurement unit that measures the energy intensity of the element contained in the coating portion of the strip electrode,
A determination device that determines whether the formation state of the coating portion of the strip electrode is based on the energy intensity;
The transport device includes a support member that supports the belt-like electrode, and the support member includes a support concave portion that has an arc shape in a side view when the belt-like electrode is viewed from the longitudinal direction.
2. The electrode inspection apparatus according to claim 1, wherein the fluorescent X-ray detection apparatus is swingable in a short direction of the strip electrode with the center of the arc of the support recess as an axis.   The electrode inspection apparatus according to claim 8, further comprising a gas injection device that injects gas toward a portion where the fluorescent X-ray detection is performed in the coating portion of the strip electrode.

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