Electrode inspection method

Abstract

To improve the inspection accuracy in an inspection method for checking the presence or absence of a composite layer regarding an electrode in which a mixture layer is partially provided on a current collector foil (for example, an electrode manufactured by partially removing a mixture layer provided on the surface of the current collector foil).SOLUTION: An electrode inspection method according to the present disclosure is a method for detecting the presence or absence of a mixture layer on the surface of the current collector foil in an electrode including the current collector foil and the mixture layer partially provided on the surface of the current collector foil. In the electrode inspection method according to the present disclosure, the presence or absence of the mixture layer on the surface of the current collector foil is detected on the basis of the intensity of reflected light of a specific visible wavelength.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for inspecting an electrode. [Background technology]

[0002] A known method for manufacturing electrodes used in batteries such as lithium-ion secondary batteries is to form a composite layer containing an active material on a current collector such as a metal foil, and then remove a portion (such as an edge) of the composite layer to manufacture a sheet-like electrode.

[0003] For example, Japanese Patent Laid-Open Publication No. 2000-149911 (Patent Document 1) discloses a method of removing a part of a composite layer by irradiating it with a laser.

[0004] In this way, for electrodes manufactured by a method of removing a portion of the electrode composite layer once formed, conventionally, inspections have typically been carried out using optical coherence tomography (OCT) to confirm whether or not any electrode composite layer remains in the areas where the composite layer should be removed (i.e., to confirm the removal of the composite layer). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-149911 Summary of the Invention [Problem to be solved by the invention]

[0006] Optical coherence tomography (OCT) determines whether or not a composite layer remains based on the measurement value of the height (position of the surface in the thickness direction) of the electrode on the surface of the sheet-like electrode. Therefore, the inspection results are affected by variations in the thickness of the current collecting foil (metal foil, etc.) and the state of the composite layer remaining after removal. Therefore, the inspection accuracy is not sufficiently high.

[0007] The present disclosure aims to improve the inspection accuracy in an inspection method for checking the presence or absence of a composite layer for an electrode having a composite layer partially provided on a collector foil (for example, an electrode manufactured by partially removing a composite layer provided on the surface of a collector foil). [Means for solving the problem]

[0008] (1) An electrode inspection method for detecting the presence or absence of a composite layer on a surface of a current collecting foil, the electrode including the composite layer being partially provided on the surface of the current collecting foil, the method comprising: An electrode inspection method comprising detecting the presence or absence of the composite layer on the surface of the current collector foil based on the intensity of reflected light of a specific visible light wavelength.

[0009] According to the inspection method (1) above, the inspection accuracy is improved because it is less susceptible to the effects of variations in the thickness of the current collector foil and the state of the composite layer remaining after removal by the laser. In addition, because the composite layer and the current collector foil usually have different spectra of reflected light at visible wavelengths, the presence or absence of a composite layer on the surface of the current collector foil can be detected with higher accuracy by performing an inspection based on the intensity of reflected light at a specific visible wavelength. Therefore, the inspection accuracy can be improved in an inspection method for checking the presence or absence of a composite layer for an electrode having a composite layer partially provided on a collector foil (for example, an electrode manufactured by partially removing a composite layer provided on the surface of a collector foil).

[0010] (2) The electrode inspection method according to (1), wherein the presence or absence of the composite layer on the surface of the current collecting foil is detected based on at least one of the intensity of reflected light of a wavelength originating from the current collecting foil and the intensity of reflected light of a wavelength originating from the composite layer.

[0011] According to the inspection method described in (2) above, the presence or absence of a composite layer on the surface of the current collector foil can be detected with higher accuracy by detecting the presence of at least one of the composite layer and the current collector foil based on the intensity of reflected light of a specific wavelength caused by at least one of the composite layer and the current collector foil.

[0012] (3) The electrode inspection method according to (2), wherein the presence or absence of the composite layer on the surface of the current collecting foil is detected based on both the intensity of reflected light at a wavelength originating from the current collecting foil and the intensity of reflected light at a wavelength originating from the composite layer.

[0013] According to the inspection method described in (3) above, the presence or absence of a composite layer on the surface of the current collecting foil can be detected with even greater accuracy by detecting the presence of both the composite layer and the current collecting foil based on both the intensity of reflected light at a wavelength originating from the current collecting foil and the intensity of reflected light at a wavelength originating from the composite layer.

[0014] (4) The electrode inspection method according to (2) or (3), wherein the wavelength originating from the composite layer is a wavelength originating from an active material contained in the composite layer.

[0015] (5) The electrode is manufactured by partially removing a composite layer provided on the surface of a current collecting foil, The electrode inspection method according to any one of (1) to (4), further comprising inspecting whether or not a remaining composite layer is present in an area where the composite layer should be removed. [Brief explanation of the drawings]

[0016] [Figure 1] 1A to 1C are schematic diagrams for explaining an electrode inspection method according to an embodiment. [Figure 2] 1 is a schematic diagram illustrating an example of an inspection device used in an electrode inspection method according to an embodiment. [Figure 3] 1A to 1C are schematic diagrams for explaining an electrode inspection method according to an embodiment. [Figure 4] 1A to 1C are schematic diagrams for explaining an electrode inspection method according to an embodiment. [Figure 5] FIG. 1 is a diagram showing reflected light spectra of a positive electrode active material and a positive electrode current collector foil (Al foil). DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present disclosure will be described. However, the present disclosure is not limited thereto. In this specification, the "positive electrode" and the "negative electrode" will be collectively referred to as "electrodes."

[0018] <Electrode inspection method> The electrode inspection method in this embodiment is a method for detecting the presence or absence of a composite layer on the surface of a current collecting foil in an electrode that includes a current collecting foil and a composite layer partially provided on the surface of the current collecting foil. In the electrode inspection method of this embodiment, the presence or absence of a composite layer on the surface of a current collector foil is detected based on the intensity of reflected light of a specific visible light wavelength.

[0019] Referring to Figure 1, the inspection method of this embodiment is used to inspect an electrode for the presence or absence of remaining composite layer 34a in an area where the composite layer should be removed, for example, when the electrode is manufactured by first removing a portion (such as an end) of composite layer 34 provided on the surface of collector foil 33.

[0020] In the inspection method of this embodiment, light including visible wavelengths is irradiated from the light source 10 onto a predetermined region on the composite layer 34 side of the electrode, and the intensity of the reflected light of at least one specific wavelength among the reflected light is measured by the light-receiving unit 1. Based on the measured intensity of the reflected light of at least one specific visible wavelength, the presence or absence of a composite layer on the surface of the current collecting foil is detected.

[0021] 2, the inspection device used in the inspection method of this embodiment includes, for example, a light-receiving sensor 21 that can detect visible light wavelengths and a spectrometer 23 that can measure the wavelength detected by the light-receiving sensor 21. The inspection device may further include a light-receiving unit 1, an optical fiber 22, an analysis computer 24, etc. The light-receiving unit 1 includes, for example, a protective glass 11, a cut filter 12, a band-pass filter 13, a lens (f200) 14, and a lens (f50) 15.

[0022] The inspection device can be installed in the electrode processing equipment together with processing equipment 4 (for example, a galvanometer scanner) for processing the electrodes. Therefore, the inspection device can be easily installed in existing processing equipment. This makes it easy to inspect all the electrodes.

[0023] Furthermore, according to the inspection method of this embodiment, electrodes can be inspected in a non-contact and non-destructive manner.

[0024] In this embodiment, it is preferable to detect the presence or absence of a composite layer on the surface of the current collecting foil based on at least one of the intensity of reflected light of a wavelength originating from the current collecting foil and the intensity of reflected light of a wavelength originating from the composite layer.

[0025] It is also more preferable to detect the presence or absence of a composite layer on the surface of the current collecting foil based on both the intensity of reflected light at a wavelength originating from the current collecting foil and the intensity of reflected light at a wavelength originating from the composite layer.

[0026] The wavelength originating from the composite layer may be, for example, a wavelength originating from the active material contained in the composite layer, but may also be a wavelength originating from a material other than the active material contained in the composite layer. However, it is preferable that the "wavelength originating from the composite layer" used as an indicator in the inspection method of this embodiment is a wavelength different from the "wavelength originating from the current collecting foil."

[0027] For example, as shown in the reflected light spectrum (spectroscopic spectrum) in Figure 5, by measuring the intensity of reflected light at one or both of the wavelengths of 480 nm (see the lower spectrum in Figure 5), which is a typical wavelength derived from aluminum (A1050) foil, and 580 nm (see the upper spectrum in Figure 5), which is a typical wavelength derived from the positive electrode active material contained in the positive electrode composite layer, it is possible to detect the presence or absence of a composite layer on the current collecting foil based on the measured value of the intensity of reflected light.

[0028] In this specification, a wavelength originating from a certain member (material) refers to a wavelength with a relatively high intensity in the reflected light spectrum of a certain material (for example, the wavelength of the peak marked with a black circle in the spectrum of Fig. 5). It is preferable to measure the intensity of the wavelength with the highest intensity (representative wavelength) among these wavelengths, and detect the presence or absence of a composite layer on the surface of the current collecting foil based on the measured intensity value.

[0029] Specifically, with reference to Figures 3 and 4, an inspection method will be described for an electrode having a composite layer 34 (positive electrode composite layer), a current collecting foil (Al foil) 33, an adhesive layer 32, and a current collecting foil (Cu foil) in this order as shown in Figure 4, in which a portion of the composite layer is melted, volatilized, and removed by irradiating laser light from the composite layer 34 side.

[0030] When composite layer 34 is being removed but not yet completely, the intensity of reflected light with a wavelength of 580 nm originating from the active material in the composite layer is high, and the intensity of reflected light with a wavelength of 480 nm originating from current collecting foil 33 is low. On the other hand, when removal of composite layer 34 is complete (as shown in FIG. 4 , when removed portion (hole) 35 formed by laser irradiation reaches current collecting foil 33), current collecting foil 33 is exposed, so the intensity of reflected light with a wavelength of 480 nm increases and the intensity of reflected light with a wavelength of 580 nm decreases.

[0031] A threshold value is set in advance for determining the presence or absence of a composite layer for the intensity of reflected light of such specific visible light wavelengths, and the presence or absence of a composite layer (e.g., removal of the composite layer) can be confirmed based on the relationship between the measured value of the reflected light intensity and the threshold value.

[0032] For example, if the intensity of the reflected light at a wavelength of 580 nm is greater than a threshold, the presence of the composite layer 34 can be detected; if it is less than the threshold, the absence of the composite layer 34 can be detected. Furthermore, if the intensity of the reflected light at a wavelength of 480 nm is less than a threshold, the presence of the composite layer 34 can be detected; if it is greater than the threshold, the absence of the composite layer 34 can be detected. The presence or absence of the composite layer 34 may be detected based on the measurement results of any one of these wavelengths, or the presence or absence of the composite layer 34 may be determined comprehensively from the detection results at both of these wavelengths. Determining the presence or absence of the composite layer 34 comprehensively from the detection results at both of these wavelengths allows for more accurate inspection.

[0033] If the laser irradiation time is too long, for example, and the removed portion (hole) 36 formed by the laser irradiation reaches the adhesive layer 32 (see FIG. 4), the current collector foil will be perforated, which is an unsuitable state for the electrode. The presence or absence of such a defect can also be detected in the same manner as above, based on the intensity of reflected light of visible wavelengths originating from the current collector foil 33 and the adhesive layer 32 (see FIG. 3).

[0034] The electrode to be inspected by the inspection method of this embodiment may be either a positive electrode or a negative electrode. The current collector foil 33 may be a positive electrode current collector foil or a negative electrode current collector foil. The mixture layer 34 may be a positive electrode mixture layer or a negative electrode mixture layer.

[0035] The positive electrode includes a positive electrode current collector foil and a positive electrode mixture layer.

[0036] The positive electrode current collector foil may be, for example, an aluminum (Al) foil.

[0037] The positive electrode mixture layer includes at least a positive electrode active material. For example, the positive electrode mixture layer may consist essentially of the positive electrode active material. In addition to the positive electrode active material, the positive electrode mixture layer may also include, for example, a conductive material, a binder, and the like. The positive electrode active material may be, for example, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, etc. (e.g., Li 1.15 Ni1 / 3 Co 1 / 3 Mn 1 / 3 The positive electrode active material may contain at least one selected from the group consisting of lithium niobate (LiNbO), lithium nickel cobalt aluminate, and lithium iron phosphate. The positive electrode active material may be subjected to a surface treatment. A buffer layer may be formed on the surface of the positive electrode active material by the surface treatment. The buffer layer may contain, for example, lithium niobate (LiNbO). The conductive material may include, for example, a conductive carbon material (eg, vapor grown carbon fiber (VGCF)). The binder may include, for example, polyvinylidene fluoride (PVdF).

[0038] The negative electrode includes a negative electrode current collector foil and a negative electrode mixture layer.

[0039] The negative electrode current collector foil may be, for example, a copper (Cu) foil, a nickel (Ni) foil, or the like.

[0040] The negative electrode mixture layer includes at least a negative electrode active material. For example, the negative electrode mixture layer may consist essentially of the negative electrode active material. In addition to the negative electrode active material, the negative electrode mixture layer may also include, for example, a conductive material, a binder, and the like. Examples of the negative electrode active material include graphite, soft carbon, hard carbon, silicon, silicon oxide, silicon-based alloys, tin, tin oxide, tin-based alloys, and lithium titanate (Li4Ti5O 12 ) may contain at least one selected from the group consisting of

[0041] The embodiments and examples disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is not limited to the above description, but is defined by the claims. It is therefore intended to include all modifications that come within the meaning and scope of equivalency of the appended claims. [Explanation of symbols]

[0042] 1 light receiving unit, 10 light source, 11 protective glass, 12 cut filter, 13 band pass filter, 14 lens (f200), 15 lens (f50), 21 light receiving sensor, 22 optical fiber, 23 spectroscope, 24 analysis computer, 3 electrode, 31 current collecting foil (Cu foil), 32 adhesive layer, 33 current collecting foil (Al foil), 34 composite layer, 34a remaining composite layer, 35, 36 removal portion, 4 processing equipment.

Claims

1. A method of manufacturing a collector foil, comprising: a removing step of partially removing a composite layer formed on a surface of the collector foil; an inspection step of detecting the presence or absence of the composite layer on the surface of the current collecting foil based on both the intensity of reflected light at a wavelength originating from the current collecting foil and the intensity of reflected light at a wavelength originating from the composite layer during the removal step, Electrode manufacturing method.

2. An electrode inspection method for detecting the presence or absence of a composite layer on a surface of a current collecting foil, the electrode including the composite layer being partially provided on a surface of the current collecting foil, the method comprising: the electrode includes a positive electrode mixture layer, a positive electrode current collector foil, an adhesive layer, a negative electrode current collector foil, and a negative electrode mixture layer in this order; detecting the presence or absence of the composite layer on the surface of the current collecting foil based on both the intensity of reflected light of a wavelength originating from the current collecting foil and the intensity of reflected light of a wavelength originating from the composite layer; an electrode inspection method for detecting whether or not a hole has formed in the current collecting foil based on both the intensity of reflected light at a wavelength originating from the current collecting foil and the intensity of reflected light at a wavelength originating from the adhesive layer.

3. The electrode inspection method according to claim 2 , wherein the wavelength originating from the composite layer is a wavelength originating from an active material contained in the composite layer.

4. the electrode is manufactured by partially removing a composite layer provided on a surface of a current collecting foil, 4. The electrode inspection method according to claim 2, further comprising inspecting whether or not a remaining composite layer is present in an area where the composite layer is to be removed.

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