JP2018098096A - Negative electrode inspection method, negative electrode manufacturing method, negative electrode inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative electrode inspection method, a negative electrode manufacturing method, and a negative electrode inspection device that are able to hinder a decrease in the reliability of inspection, due to a change in inspection environment, in the inspection of formation of a part coated with a material for a heat resistant layer.SOLUTION: To inspect a coated part 18 of a belt-like electrode 19, a comparison electrode piece 80 having a comparison coated part 81 of predetermined basis weight is used. The belt-like electrode 19 is longitudinally conveyed while the comparison electrode piece 80 is disposed laterally outside the belt-like electrode 19, also, a fluorescent X-ray detection device 41 is reciprocally moved in a lateral direction of the belt-like electrode 19, and fluorescent X-rays β, generated from the belt-like electrode 19 and the comparison electrode piece 80, are respectively generated. The energy strength of a light element included in the coated part 18 of the belt-like electrode 19 and that included in the comparison coated part 81 of the comparison electrode piece 80 are measured from the respective fluorescent X-rays β thus detected. The belt-like electrode 19 and the comparison electrode piece 80 are compared for the measured energy strength. On the basis of the result of the comparison, the quality of formation of the coated part 18 of the belt-like electrode 19 is determined.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an inspection method, a manufacturing method, and an inspection of a negative electrode having a current collector, a negative electrode active material layer present on both surfaces or one surface of the current collector, and a heat-resistant layer present on the surface of the negative electrode active material layer. Relates to the device.

  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 or one side of the metal foil, and a heat-resistant layer present on the surface of the active material layer The electrode which has is known (for example, refer 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 heat-resistant layer material is good. In Patent Document 1, fluorescent X-rays generated from a metal foil on which an active material layer and a heat-resistant layer material coating portion are formed are measured, and the thickness (weight per unit area) of the heat-resistant layer material coating portion is determined from the measurement result. Acquired and inspected whether the formation state of the coated part is good.

JP 2009-193906 A

  However, the temperature and humidity of the environment in which fluorescent X-rays are detected may change and affect the measurement results. In this case, for example, it is determined that the coating weight to be inspected is inferior despite being within the target range, or is determined to be non-defective though the weight is significantly larger or smaller than the target value. As a result, the reliability of the inspection is lowered.

  The present invention has been made in order to solve the above-mentioned problems, and its purpose is to provide a negative electrode capable of suppressing a decrease in inspection reliability due to changes in the inspection environment in the inspection of the formation state of the coated portion of the heat-resistant layer material. An electrode inspection method, a negative electrode manufacturing method, and a negative electrode inspection device are provided.

  The negative electrode inspection method for solving the above problems includes a current collector, a negative electrode active material layer present on both surfaces or one surface of the current collector, and a heat resistant layer present on the surface of the negative electrode active material layer. A long strip current collector, a negative electrode active material layer present on both sides or one side of the long strip current collector, and heat resistance on the surface of the negative electrode active material layer A belt-like electrode having a coating portion which is a precursor of the heat-resistant layer formed by coating a layer material, and a comparative coating portion formed so that the heat-resistant layer material has a predetermined basis weight. The comparison electrode is carried out, the belt-like electrode is transported in the longitudinal direction in a state in which the comparison electrode is disposed outside the belt-like electrode in the short direction, and the fluorescent X-ray detection device is connected to the short electrode of the belt-like electrode. Fluorescence X generated from the strip electrode and the comparison electrode by reciprocating in the hand direction A detecting step for detecting each of the above, a measuring step for measuring energy intensity of each light element contained in the coating portion of the strip electrode and the comparative coating portion of the comparison electrode from the fluorescent X-ray, and the strip shape Based on the comparison process in the comparison process in which the energy intensity of the light element contained in the coating part of the electrode and the energy intensity of the light element contained in the comparison coating part of the comparison electrode are compared in the comparison process And determining the quality of the formation state of the coating part of the strip electrode.

  According to this, fluorescent X-rays generated from the strip electrode that is the inspection target and fluorescent X-rays generated from the comparison electrode that is the comparison target are detected in the same inspection environment. For this reason, even if the fluorescent X-ray of the element contained in the coating portion of the strip electrode is affected by the change in the inspection environment, the fluorescent X-ray of the element contained in the comparative coating portion of the comparative electrode is the same. Affected by. Then, from the fluorescent X-rays detected in the same inspection environment, the energy intensity of the light element contained in the coating portion of the strip electrode and the energy intensity of the light element contained in the comparison coating portion of the comparison electrode are measured. By comparing, the quality of the formation state of the coating part of the heat-resistant layer material of the strip electrode is determined. Therefore, in the inspection of the formation state of the coating part of the heat-resistant layer material, it is possible to perform an inspection taking into consideration the inspection environment, and it is possible to suppress a decrease in the inspection reliability due to a change in the inspection environment. Further, since the fluorescent X-rays generated from the strip electrode and the fluorescent X-rays generated from the comparison electrode are detected by the same fluorescent X-ray detection device, different fluorescent X-ray detection devices are used for the strip electrode and the comparison electrode. It is not necessary to take into account variations in detection results that occur when used. Moreover, since a detection process is performed conveying a strip | belt-shaped electrode, it can detect, without reducing the productivity of a negative electrode.

In the inspection method for the negative electrode, the light element whose energy intensity is measured in the measurement step is preferably aluminum or silicon.
According to this, the formation state of the coating part of the heat-resistant layer material can be inspected by the energy intensity of the fluorescent X-rays emitted from aluminum or silicon.

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

In the inspection method of the negative electrode, the comparative electrode is preferably disposed on the same plane as the strip electrode.
According to this, since the distance between the fluorescent X-ray detection device and the strip electrode and the distance between the fluorescent X-ray detection device and the comparison electrode are substantially the same distance, the fluorescent X-ray detection is quantitatively performed. be able to.

  In the inspection method of the negative electrode, in the measurement step, the light X-ray fluorescence intensity of the light element having the first energy and the X-ray fluorescence intensity of the light element having the second energy Is preferably measured.

According to this, since two types of energy intensity are used in the comparison step, the inspection accuracy of the coated portion of the heat-resistant layer material is improved as compared with the case where one type of energy intensity is used.
A method of manufacturing a negative electrode for solving the above problems includes a current collector, a negative electrode active material layer present on both surfaces or one surface of the current collector, and a heat-resistant layer present on the surface of the negative electrode active material layer. In the method for producing a negative electrode having a coating, a coating part which is a precursor of the heat-resistant layer by applying a heat-resistant layer material on the surface of the negative electrode active material layer formed on both sides or one side of a long strip-shaped current collector The method for inspecting an electrode according to any one of claims 1 to 5, comprising: a coating step for forming a coating layer; and an inspection step for inspecting a coating portion of the heat-resistant layer material. The gist is to change the coating amount of the heat-resistant layer material in the coating process based on the determination result in the determination process.

According to this, since the determination result of the formation state of the coating part is reflected in the coating amount of the heat-resistant layer material, the negative electrode in which the formation state of the coating part of the heat-resistant layer material becomes defective can be reduced.
Moreover, about the manufacturing method of the said negative electrode, it is preferable that the said determination process is performed before the drying process which dries the said coating part.

  According to this, since the determination result can be reflected in the coating amount of the heat-resistant layer material earlier than when the determination step is performed after the drying step, the negative electrode in which the formation state of the coated portion of the heat-resistant layer material becomes defective Can be further reduced.

Moreover, about the manufacturing method of the said negative electrode, it is preferable to use a gravure coating apparatus for the said coating process.
In coating using a gravure coating device, the basis weight of the coating part depends on the rotation speed of the gravure roll, so when changing the basis weight of the coating part, it is only necessary to change the rotation speed of the gravure roll. No need for complicated adjustment work.

  A negative electrode inspection apparatus for solving the above problems includes a current collector, a negative electrode active material layer present on both sides or one side of the current collector, and a heat-resistant layer present on the surface of the negative electrode active material layer. A negative electrode inspection apparatus comprising: a long strip current collector; a negative electrode active material layer present on both sides or one side of the long strip current collector; and a heat resistant surface on the negative electrode active material layer A transport device that transports a strip electrode having a coating portion that is a precursor of the heat-resistant layer formed by coating a layer material in a longitudinal direction; and a reciprocating operation in a short direction of the strip electrode; Fluorescence generated from the comparison electrode disposed on the outer side in the short-side direction of the band-shaped electrode, having the band-shaped electrode and the comparative coating portion formed so that the heat-resistant layer material has a predetermined basis weight. A fluorescent X-ray detection device for detecting X-rays respectively, and from the fluorescent X-rays, A measuring unit for measuring the energy intensity of the light element contained in the coating part of the electrode and the comparative coating part of the comparative electrode, and the energy intensity of the light element contained in the coating part of the strip electrode, Based on the comparison result by the comparison part and the comparison part by the comparison part which compares the energy intensity of the light element contained in the comparison application part of the comparison electrode, the quality of the formation state of the application part of the strip electrode is judged. The gist is to include a determination device.

  According to this, the fluorescent X-ray detection apparatus detects fluorescent X-rays generated from the strip-shaped electrode that is the inspection target and fluorescent X-rays generated from the comparison electrode that is the comparison target in the same inspection environment. . For this reason, even if the fluorescent X-ray of the element contained in the coating portion of the strip electrode is affected by the change in the inspection environment, the fluorescent X-ray of the element contained in the comparative coating portion of the comparative electrode is the same. Affected by. Then, from the fluorescent X-rays detected in the same inspection environment, the energy intensity of the light element contained in the coating portion of the strip electrode and the energy intensity of the light element contained in the comparison coating portion of the comparison electrode are measured. By comparing, the quality of the formation state of the coating part of the heat-resistant layer material of the strip electrode is determined. Therefore, in the inspection of the formation state of the coating part of the heat-resistant layer material, it is possible to perform an inspection taking into consideration the inspection environment, and it is possible to suppress a decrease in the inspection reliability due to a change in the inspection environment. In addition, since one fluorescent X-ray detection device detects fluorescent X-rays generated from the strip electrode and fluorescent X-rays generated from the comparison electrode, fluorescent X-ray detection is different between the strip electrode and the comparison electrode. It is not necessary to take into account variations in detection results that occur when using an apparatus. In addition, since the inspection is performed while transporting the strip electrode by the transport device, the inspection can be performed without reducing the productivity of the negative electrode.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the reliability of a test | inspection by the change of a test | inspection environment can be suppressed in the test | inspection of the formation state of the coating part of heat-resistant layer material.

The perspective view of a negative electrode. (A) is a schematic side view which shows the coating process and detection process in a heat-resistant layer formation process, (b) is a schematic plan view which shows the detection process in a heat-resistant layer formation process.

Hereinafter, an embodiment in which a negative electrode inspection method is embodied as a secondary battery negative electrode inspection method will be described with reference to FIGS. 1 and 2.
Although not shown, the secondary battery as a power storage device using the negative 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 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.

  As shown in FIG. 1, the 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 present on both surfaces of the metal foil 11. The metal foil 11 is made of a metal (for example, copper) that does not contain aluminum as a light 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 heat resistant layer 15 that covers the entire surface of the negative electrode active material layer 12. The heat-resistant layer 15 includes alumina particles as ceramic particles and a resin binder, and the alumina particles or alumina particles and the active material particles on the surface of the negative electrode active material layer 12 are bonded to each other through the binder to form a layer structure. Have. The heat-resistant temperature of the heat-resistant layer 15 mainly composed of alumina particles is higher than that of a resin separator. Moreover, since the heat-resistant layer 15 has alumina particles as a main component, it contains aluminum as a light element as a main component. The light element is an 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 reduce the weight energy density of the negative electrode 10.

  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 sides of the long metal foil 11 and a heat resistant layer formation in which the heat resistant layer 15 is formed on the surface of the negative electrode active material layer 12. And a cutting step of cutting the metal foil 11 on which the negative electrode active material layer 12 and the heat-resistant layer 15 are formed into the shape of the negative electrode 10.

  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.

As shown in FIG. 2A, the heat-resistant layer forming step includes a coating step, an inspection step, and a drying step.
In the coating process, a ceramic slurry 17 as a heat-resistant layer material is applied to the surface of the negative electrode active material layer 12 of the electrode material 16 while conveying the electrode material 16 in the longitudinal direction, and a coating that becomes a precursor of the heat-resistant layer 15. This is a process of forming the work part 18. Therefore, the coating part 18 is formed by the coating of the ceramic slurry 17.

  The transport device 20 used in the heat-resistant layer forming step includes a supply roll 21, a take-up roll 22, and a plurality of guide rolls 23 arranged at a location between the supply roll 21 and the take-up roll 22. Each of the rolls 21 to 23 is rotatably supported by a support device (not shown). The electrode material 16 is wound around the supply roll 21. The electrode material 16 supplied from the supply roll 21 is conveyed by being wound around the winding roll 22. 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.

  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 non-aqueous 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. And in 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 roll 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.

  The inspection step is a step of inspecting the formation state of the coating part 18. The inspection process is performed using the negative electrode inspection apparatus 40. The inspection device 40 includes a fluorescent X-ray detection device 41, a measurement device 44, and a determination device 51, which will be described in detail later.

  The inspection step includes a detection step of detecting fluorescent X-rays β generated from the strip electrode 19 and a later-described comparative electrode piece 80 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. In the present embodiment, as a fluorescent X-ray detection device 41, a handheld metal material separator (model: X-MET8000, X-ray tube: voltage 50 kV, rhodium target, detector: silicon drift type) manufactured by Oxford is used at room temperature. Although used, it is not limited to this.

  2A and 2B, the fluorescent X-ray detection apparatus 41 includes an X-ray tube 42 that can irradiate primary X-rays α, and a detection unit 43 that can detect fluorescent X-rays β. Is an integrated device. The X-ray fluorescence detection apparatus 41 exists in a state where a predetermined interval is provided from the upper end portion of the back roll 33. Further, the fluorescent X-ray detection device 41 can reciprocate on the flow line L along the short direction of the belt-like electrode 19 while maintaining this interval. A comparison electrode piece 80 as a comparison electrode is disposed on the flow line L of the fluorescent X-ray detection device 41 and on both outer sides in the short direction of the strip electrode 19. The end of the flow line L is located on the comparison electrode piece 80. Therefore, the fluorescent X-ray detection device 41 detects the fluorescent X-ray β generated from the strip electrode 19 when it is within the range of the strip electrode 19 on the flow line L. When the fluorescent X-ray detection device 41 is at one end or the other end on the flow line L, the fluorescent X-ray detection device 41 detects the fluorescent X-ray β generated from the comparison electrode piece 80.

  The comparative electrode piece 80 has a rectangular sheet shape. Further, the comparative electrode piece 80 includes a metal foil piece, a negative electrode active material layer present on both sides of the metal foil piece, and a comparative coating formed by coating the ceramic slurry 17 on the surface of the negative electrode active material layer. Part 81. For the metal foil piece, the negative electrode active material layer, and the comparative coating portion 81, the same material as that of the metal foil 11, the negative electrode active material layer 12, and the coating portion 18 of the strip electrode 19 is used. The comparative electrode piece 80 exists on the same plane as the strip electrode 19. Among the comparison electrode pieces 80, the one disposed outside the one end in the short direction of the strip electrode 19 is referred to as a first comparison electrode piece 80a, and the one disposed outside the other end in the short direction of the strip electrode 19 The second comparison electrode piece 80b is used. The first comparison electrode piece 80a and the second comparison electrode piece 80b differ in the basis weight of the comparison coating part 81. The basis weight of the first comparison coating portion 81a of the first comparison electrode piece 80a is formed to be an upper limit in the target range of the basis weight of the coating portion 18 of the strip electrode 19. On the other hand, the basis weight of the second comparison coating portion 81b of the second comparison electrode piece 80b is formed to be a lower limit in the target range of the basis weight of the coating portion 18 of the strip electrode 19.

  In the detection step, the X-ray tube 42 of the fluorescent X-ray detection device 41 is set to 1 in the irradiation range Q (for example, a rectangular range extending in the longitudinal direction 5 mm and the lateral direction 5 mm) on the strip electrode 19 or the comparative electrode piece 80. Next, X-ray α is irradiated. 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 or the comparative electrode piece 80 are in the excited state, and the fluorescent X-ray β is generated when returning from the excited state to the stable state. . The detection unit 43 of the fluorescent X-ray detection device 41 detects this fluorescent X-ray β.

  As described above, the detection step is performed while the belt-like electrode 19 is transported by the transport device 20 and the fluorescent X-ray detection device 41 is reciprocated between one end and the other end of the flow line L. Therefore, the irradiation range Q moves on the strip electrode 19 in the longitudinal direction and the lateral direction, and the entire longitudinal direction and the lateral direction of the strip electrode 19 are inspected. In this embodiment, since the fluorescent X-ray detection device 41 is continuously reciprocated, the locus of the irradiation range Q has a sine wave shape. When the fluorescent X-ray detection device 41 moves to one end on the flow line L, the fluorescent X-ray detection device 41 detects the fluorescent X-ray β generated from the first comparison electrode piece 80 a and outputs the detection result to the measurement device 44. When the fluorescent X-ray detection device 41 moves to the other end on the flow line L, the fluorescent X-ray detection device 41 detects the fluorescent X-ray β generated from the second comparison electrode piece 80 b and outputs the detection result to the measurement device 44. In addition, the fluorescent X-ray detection device 41 moves from one end (other end) to the other end (one end) on the flow line L, and a plurality of irradiation ranges Q (for example, existing at different positions on the strip electrode 19 (for example, In the first to fifth irradiation ranges Q1 to Q5), fluorescent X-rays β generated from the strip electrode 19 are detected. Then, the detection unit 43 outputs the detection results of the strip electrode 19 in the first to fifth irradiation ranges Q1 to Q5 to the measuring device 44.

  By the way, the detection unit 43 detects fluorescent X-rays β of a plurality of elements contained in the strip electrode 19 and the comparison electrode piece 80. The fluorescent X-ray β has a unique energy that is different for each element. For example, since the metal foil 11 and the metal foil piece are made of copper, the detection unit 43 detects the fluorescent X-ray β having energy unique to copper. Further, since the coating unit 18 and the comparative coating unit 81 include alumina particles (aluminum), the detection unit 43 detects fluorescent X-rays β having energy specific to aluminum. In addition, 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 or the comparative electrode piece 80 in the irradiation range Q. The detection result of the fluorescent X-ray β output from the detection unit 43 to the measurement device 44 includes the energy intensity of a plurality of elements included in the strip electrode 19 or the comparison electrode piece 80.

  The inspection step includes a measurement step of measuring the energy intensity of aluminum contained in the strip electrode 19 and the comparative electrode piece 80 from the detection result in the detection step. The measurement process is performed using the measurement device 44 of the inspection device 40. The measuring device 44 is signal-connected to the fluorescent X-ray detection device 41.

  The measuring device 44 includes a measuring unit 45 that measures the energy intensity of aluminum. Detection results for the first comparison electrode piece 80 a, the second comparison electrode piece 80 b, and the strip electrode 19 are input to the measurement unit 45 from the detection unit 43. The measurement unit 45 measures the energy intensity of aluminum contained in the first comparison electrode piece 80a. Since the first comparison electrode piece 80a has the first comparison coating portion 81a formed so that the basis weight is the upper limit value of the target range, the aluminum content is large and the energy intensity of the aluminum is increased. . The measurement unit 45 sets the measurement value at the first comparison electrode piece 80a as the upper limit value AH. The measurement unit 45 measures the energy intensity of aluminum contained in the second comparison electrode piece 80b. Since the second comparison electrode piece 80b has the second comparison coating portion 81b formed so that the basis weight is the lower limit value of the target range, the aluminum content is small and the energy intensity of the aluminum is weakened. . The measurement unit 45 sets the measurement value at the second comparison electrode piece 80b as the lower limit value AL. Moreover, the measurement part 45 each measures the energy intensity of the aluminum contained in the strip | belt-shaped electrode 19 about the 1st-5th irradiation range Q1-Q5, and sets each measured value as 1st-5th test value A1-A5. To do. The measuring unit 45 measures the energy intensity each time a detection result is output from the detecting unit 43, and updates the upper limit value AH, the lower limit value AL, and the first to fifth inspection values A1 to 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. The comparison process is performed using the comparison unit 46 of the measuring device 44. The comparison unit 46 receives the first to fifth inspection values A1 to A5, the upper limit value AH, and the lower limit value AL from the measurement unit 45. The comparison unit 46 compares the first inspection value A1 with the upper limit value AH. The comparison unit 46 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. Moreover, the comparison part 46 compares 1st test value A1 and lower limit AL. The comparison unit 46 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 46 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 or not the formation state of the coating part 18 of the strip electrode 19 is good based on the signals S <b> 1 to S <b> 4 generated by the comparison unit 46. The determination process is performed by the determination device 51 of the inspection device 40. The determination device 51 is signal-connected to the measurement device 44. Signals S <b> 1 to S <b> 4 are input from the comparison unit 46 to the determination device 51. The determination device 51 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 46 for the first inspection value A1, that is, when the first inspection value A1 is not more than the upper limit value AH and not less than the lower limit value AL, the determination device 51 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 46 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 51 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). The determination device 51 forms the coating unit 18 in the first irradiation range Q1 when the signal S4 is input from the comparison unit 46 for the first inspection value A1, that is, when the first inspection value A1 is smaller than the lower limit value AL. The state is determined to be defective 2 (the basis weight is outside the target range). The determination device 51 performs the same determination for the second to fifth inspection values A2 to A5.

  In addition, when the determination device 51 determines that three or more of the coating parts 18 in the first to fifth irradiation ranges Q1 to Q5 are defective 1, a signal of “excess basis weight” to the control device 35. Is output. When the determination device 51 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 51 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.

The manufacturing method of the negative electrode 10 includes the above-described coating process and an inspection process (detection process, measurement process, comparison process, and determination process), and further includes a process of adjusting the basis weight of the coating portion 18.
After the inspection process, the strip electrode 19 is conveyed into the drying device 60. The coating part 18 is dried with the drying apparatus 60, and becomes a heat-resistant layer precursor. Although not shown, the strip electrode 19 on which the heat-resistant layer precursor is formed is cut into the shape of the negative electrode 10 in the cutting step. The heat resistant layer 15 is formed from the heat resistant layer precursor. In this way, the sheet-like negative electrode 10 is manufactured.

Next, operations and effects of this embodiment will be described.
(1) The fluorescent X-rays β generated from the strip electrode 19 that is the inspection target and the fluorescent X-rays β generated from the comparative electrode piece 80 that is the comparison target are detected in the same inspection environment. For this reason, even if the fluorescent X-ray β of the element contained in the coating portion 18 of the strip electrode 19 is affected by the change in the inspection environment, the element contained in the comparison coating portion 81 of the comparison electrode piece 80 The fluorescent X-ray β is similarly affected. Then, from the fluorescent X-rays β detected in the same inspection environment, the energy intensity of aluminum contained in the coating part 18 of the strip electrode 19 and the energy intensity of aluminum contained in the comparison coating part 81 of the comparison electrode piece 80 Is measured and compared to determine whether or not the formation state of the coating portion 18 of the strip electrode 19 is good. Therefore, in the inspection of the formation state of the coating part 18 of the strip electrode 19, it is possible to perform an inspection taking the inspection environment into account, and it is possible to suppress a decrease in inspection reliability due to a change in the inspection environment. Further, since the fluorescent X-ray β generated from the strip electrode 19 and the fluorescent X-ray β generated from the comparative electrode piece 80 are detected by the same fluorescent X-ray detection device 41, the strip electrode 19 and the comparative electrode piece 80 are detected. Therefore, it is not necessary to take into consideration variations in detection results that occur when different fluorescent X-ray detection devices are used. Further, since the detection step is performed while the belt-like electrode 19 is being transported by the transport device 20, it can be detected without reducing the productivity of the negative electrode 10.

(2) By measuring and comparing the energy intensity of fluorescent X-rays emitted from aluminum which is a light element, the formation state of the coating part 18 of the strip electrode 19 can be inspected.
(3) In the detection process, since the fluorescent X-ray detection device 41 is continuously reciprocated while the belt-like electrode 19 is conveyed, the locus of the irradiation range Q becomes a sine wave. Therefore, the whole longitudinal direction and short direction of the coating part 18 can be inspected.

  (4) Since the first and second comparison electrode pieces 80a and 80b are arranged on the same plane as the strip electrode 19, the distance between the fluorescent X-ray detector 41 and the strip electrode 19 and the fluorescent X-ray detector The distance between 41 and the comparative electrode piece 80 is kept constant. Therefore, the fluorescent X-ray β can be detected quantitatively.

  (5) The control device 35 reflects the quality of the formation state of the coating portion 18 determined by the determination device 51 in the coating amount of the ceramic slurry 17, and thus the negative electrode 10 in which the formation state of the coating portion 18 becomes defective. Can be reduced.

  (6) Since the determination step is performed before the drying step of drying the coating unit 18, the determination result can be reflected in the coating amount of the ceramic slurry 17 earlier than when the determination step is performed after the drying step. . Therefore, the negative electrode 10 in which the formation state of the coating part 18 becomes defective can be further reduced.

  (7) The gravure coating apparatus 30 is used for the coating process. In coating using the gravure coating device 30, the basis weight of the coating unit 18 depends on the rotational speed of the gravure roll 32. Therefore, when changing the basis weight of the coating unit 18, the rotational speed of the gravure roll 32 is changed. It only needs to be changed, and no complicated adjustment work is required.

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 heat resistant 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.
In the above embodiment, the ceramic particles included in the heat-resistant layer 15 are alumina particles, but may be aluminum nitride. The ceramic particles may be oxides or nitrides of other light elements such as silicon dioxide and silicon nitride.

  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 heat-resistant 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 light element fluorescent X-rays β contained in the coating portion 18 of the strip electrode 19 or the comparison coating portion 81 of the comparison electrode piece 80 may have a plurality of intrinsic energies. For example, the fluorescent X-ray β of aluminum has a first specific energy and a second specific energy. In this case, the measurement unit 45 may measure the energy intensity of the fluorescent X-ray β of aluminum having the first intrinsic energy and the energy intensity of the fluorescent X-ray β of aluminum having the second intrinsic energy, respectively. . Since the comparison process can be performed using two types of energy intensity, the inspection accuracy of the formation state of the coated portion 18 is improved as compared with the case where one type of energy intensity is used.

  The X-ray fluorescence detector 41 may reciprocate without maintaining a predetermined distance from the back roll 33. However, since the distance between the fluorescent X-ray detection device 41 and the strip electrode 19 or the comparative electrode piece 80 changes, it is preferable to correct the measurement result of the energy intensity.

  If the coating part 18 is formed, the arrangement position of the fluorescent X-ray detection device 41 may not be above the back roll 33. For example, the fluorescent X-ray detection device 41 may be disposed at a position on the metal foil 11 side with respect to the strip electrode 19 on which the coating part 18 is formed. In this case, the X-ray tube 42 of the fluorescent X-ray detection device 41 irradiates the primary X-ray α from the metal foil 11 side. Moreover, although the detection process was performed before the drying process, it may be performed after the drying process.

  The comparative electrode piece 80 may not be disposed on the same plane as the strip electrode 19. However, since the distance between the fluorescent X-ray detection device 41 and the strip electrode 19 and the distance between the fluorescent X-ray detection device 41 and the comparison electrode piece 80 are different distances, the measurement result of the energy intensity is corrected. preferable.

  In the above embodiment, while the fluorescent X-ray detection device 41 moves from one end (other end) on the flow line L to the other end (one end), detection is performed in the five irradiation ranges Q1 to Q5 on the strip electrode 19. However, the number of irradiation ranges Q may be changed as appropriate.

In the above embodiment, the fluorescent X-ray detection device 41 is continuously reciprocated, but the reciprocating operation may be intermittently stopped.
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. However, the average of the measured values may be taken for the first to fifth irradiation ranges Q1 to Q5, and the average value of the energy intensity may be set as one inspection value.

The shape of the comparative electrode piece 80 may be appropriately changed within a range where the area is larger than the irradiation range Q.
The configuration of the comparative electrode piece 80 may be changed as appropriate as long as the comparative coating portion 81 is included, such as a configuration in which the metal foil and the negative electrode active material layer are eliminated. However, the configuration other than the comparative coating unit 81 is configured not to include light elements used for measuring the energy intensity.

  In the above embodiment, the comparison electrode pieces 80 are arranged on both outer sides of the strip electrode 19 in the short direction, but may be arranged only on one outer side of the strip electrode 19 in the short direction. In this case, the comparative coating part 81 is formed so as to be a target value of the basis weight of the coating part 18 of the strip electrode 19. Further, in the above embodiment, the comparison coating portions 81a and 81b of the first comparison electrode piece 80a and the second comparison electrode piece 80b have different basis weights, but the same basis weight (application of the strip electrode 19). (The target value of the basis weight of the unit 18).

  In this case, the difference between the energy intensity of aluminum contained in the comparative coating part 81 of the comparative electrode piece 80 and the energy intensity of aluminum contained in the coating part 18 of the strip electrode 19 in the irradiation range Q is calculated. When the calculated difference is smaller than a predetermined value, the determination device 51 determines that the formation state of the coating portion 18 in the irradiation range Q is good, and when the calculated difference is equal to or larger than the predetermined value, the irradiation range. The formation state of the coating part 18 at Q is determined to be defective.

The condition for the determination device 51 to output a signal of “overweight per unit weight” or “underpercent per unit weight” to the control unit 35 may be changed as appropriate.
○ In the above embodiment, the determination of the quality of the coating portion 18 is used by feeding back to the coating process. However, for the selection of non-defective / defective products of the negative electrode 10 on which the heat-resistant layer 15 is formed. It may be used.

In the above embodiment, the active material layer forming step, the heat-resistant layer forming step, and the cutting step are performed in separate production lines, but may be performed continuously in the same production line.
The fluorescent X-ray detection device 41 and the measurement device 44 may be integrated or separated.

(Circle) You may apply to the inspection method of the negative electrode for winding type electrode assemblies not only the inspection method of the negative electrode for laminated electrode assemblies.
(Circle) the inspection method of the negative electrode 10 in the said embodiment may be applied to the inspection method of the negative electrode used for electrical storage apparatuses, such as an electrode used for a nickel hydride secondary battery, and a lithium capacitor, for example.

  DESCRIPTION OF SYMBOLS 10 ... Negative electrode, 11 ... Metal foil as a collector, 12 ... Negative electrode active material layer, 15 ... Heat-resistant layer, 17 ... Ceramic slurry as heat-resistant layer material, 18 ... Coating part, 19 ... Strip electrode, 20 ... Conveying device, 30 ... gravure coating device, 40 ... inspection device, 41 ... fluorescent X-ray detection device, 44 ... measuring device, 45 ... measuring unit, 46 ... comparison unit, 51 ... determination device, 80 ... as comparison electrode Comparative electrode piece, 81... Comparative coating portion, .beta.

Claims (9)

A method for inspecting a negative electrode having a current collector, a negative electrode active material layer present on both or one side of the current collector, and a heat-resistant layer present on the surface of the negative electrode active material layer,
The long current collector, the negative electrode active material layer existing on both sides or one side of the long current collector, and the heat resistant layer material applied to the surface of the negative electrode active material layer A strip electrode having a coating part which is a precursor of a heat-resistant layer;
It is performed using a comparative electrode having a comparative coating portion formed so that the heat-resistant layer material has a predetermined basis weight,
The belt-like electrode is transported in the longitudinal direction in a state where the comparison electrode is disposed outside the belt-like electrode in the short-side direction, and the fluorescent X-ray detector is reciprocated in the short-side direction of the belt-like electrode. And a detection step of detecting each fluorescent X-ray generated from the comparison electrode,
From the fluorescent X-ray, a measurement step of measuring the energy intensity of each light element contained in the coating portion of the strip electrode and the comparative coating portion of the comparative electrode,
A comparison step for comparing the energy intensity of the light element contained in the coating portion of the strip electrode and the energy intensity of the light element contained in the comparison coating portion of the comparative electrode,
Based on the comparison result in the comparison step, a determination step of determining the quality of the formation state of the coating portion of the strip electrode,
A negative electrode inspection method comprising:   The negative electrode inspection method according to claim 1, wherein the light element whose energy intensity is measured in the measuring step is aluminum or silicon.   The negative electrode inspection method according to claim 1, wherein in the detection step, the fluorescent X-ray detection device is continuously reciprocated.   The negative electrode inspection method according to claim 1, wherein the comparison electrode is disposed on the same plane as the strip electrode.   5. The energy intensity of the fluorescent X-ray of the light element having the first energy and the energy intensity of the fluorescent X-ray of the light element having the second energy are measured in the measuring step. The inspection method of the negative electrode as described in any one of these. In a method for producing a negative electrode having a current collector, a negative electrode active material layer present on both or one side of the current collector, and a heat-resistant layer present on the surface of the negative electrode active material layer,
A coating step of coating a heat-resistant layer material on the surface of the negative electrode active material layer formed on both sides or one side of the long belt-shaped current collector to form a coating portion that is a precursor of the heat-resistant layer;
An inspection process for inspecting the coating portion of the heat-resistant layer material;
With
The inspection step is performed by the electrode inspection method according to any one of claims 1 to 5,
A method for producing a negative electrode, comprising: changing a coating amount of the heat-resistant layer material in the coating step based on a determination result in the determination step.   The said determination process is a manufacturing method of the negative electrode of Claim 6 performed before the drying process which dries the said coating part.   The manufacturing method of the negative electrode of Claim 6 or Claim 7 which uses a gravure coating apparatus for the said coating process. An inspection apparatus for a negative electrode having a current collector, a negative electrode active material layer present on both or one side of the current collector, and a heat-resistant layer present on the surface of the negative electrode active material layer,
The long current collector, the negative electrode active material layer existing on both sides or one side of the long current collector, and the heat resistant layer material applied to the surface of the negative electrode active material layer A transport device for transporting a strip electrode having a coating part which is a precursor of the heat-resistant layer in the longitudinal direction;
The belt-like electrode is capable of reciprocating in the short direction of the belt-like electrode, and has a comparative coating portion formed so that the belt-like electrode and the heat-resistant layer material have a predetermined weight per unit area. A fluorescent X-ray detector for detecting fluorescent X-rays generated from the comparative electrodes arranged on the outside in the hand direction;
From the fluorescent X-ray, a measurement unit for measuring the energy intensity of each light element contained in the coating part of the strip electrode and the comparison coating part of the comparison electrode,
A comparison unit for comparing the energy intensity of the light element contained in the coating part of the strip electrode and the energy intensity of the light element contained in the comparison coating part of the comparison electrode,
Based on the comparison result by the comparison unit, a determination device for determining the quality of the formation state of the coating portion of the strip electrode,
An inspection apparatus for a negative electrode, comprising:

Images