JP2019197650A - Inspection method of electrode layer and manufacturing method of battery - Google Patents

Abstract

To detect the moisture content in an electrode layer with high accuracy without interrupting manufacturing of the electrode layer.SOLUTION: An inspection method of an electrode layer (3) in the electrode layer of a battery includes a step (S4) of detecting the moisture content in the electrode layer (3) during conveyance of a sheet of the electrode layer (3) in a manufacture line which unwinds and conveys a roll body of electrode foil (2), laminates the film of the electrode material on the electrode foil (2), takes up the obtained sheet of the electrode layer (3) and forms the roll body. The inspection method emits the laser beam to the electrode layer (3), receives coherent anti-Stokes Raman scattering light from the electrode layer (3), and detects the vibration peak of the water molecule from the spectrum of the received coherent anti-Stokes Raman scattering light in the step (S4) of detecting the moisture content.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrode layer inspection method and a battery manufacturing method.

  Lithium ion batteries, nickel metal hydride batteries, and the like have a structure in which positive electrode layers and negative electrode layers are alternately stacked via separators. The electrode layer can be manufactured roll-to-roll. For example, an electrode material sheet is applied onto a sheet of electrode foil to be conveyed, and a film of the electrode material is laminated, whereby the electrode layer sheet is continuously manufactured (see, for example, Patent Document 1).

JP 2014-192043 A

  Since the electrode layer easily deteriorates when it contains moisture, an inspection for detecting moisture in the electrode layer is performed when the electrode layer is manufactured. Usually, a sample is prepared by cutting off a part of the electrode layer sheet in an atmosphere of an inert gas such as argon gas, and moisture in the sample is detected by the Karl Fischer method or the like.

  However, when the electrode layer is continuously produced by roll-to-roll, production must be interrupted for inspection, and production efficiency is reduced. In addition, it is necessary to cut the electrode layer sheet for preparing the sample, and it becomes difficult to obtain a long sheet of the electrode layer.

  An object of this invention is to detect the water | moisture content in an electrode layer with high precision, without interrupting manufacture of an electrode layer.

  The method for inspecting the electrode layer of the battery according to the present invention unwinds and conveys a roll body of the electrode foil, laminates a film of the electrode material on the electrode foil, winds up and rolls the obtained electrode layer sheet In a production line for forming a body, the method includes a step of detecting moisture in the electrode layer during conveyance of the sheet of the electrode layer, and the step of detecting moisture emits laser light to the electrode layer, Coherent anti-Stokes Raman scattered light is received from the electrode layer, and a vibration peak of water molecules is detected from the spectrum of the received coherent anti-Stokes Raman scattered light.

  The method for producing a battery according to the present invention is a method for producing a battery having an electrode layer, the step of unwinding and transporting a roll of electrode foil, applying an electrode material ink on the electrode foil, Forming the film, drying the electrode material film to obtain the electrode layer, detecting moisture in the electrode layer, and winding the electrode layer after detecting the moisture A step of forming a roll body, and a step of adjusting a drying condition of the film of the electrode material according to the detection result of the moisture. In the step of detecting the moisture, a laser beam is applied to the electrode layer. It emits light, receives coherent anti-Stokes Raman scattering light from the electrode layer, and detects a vibration peak of water molecules from the spectrum of the received coherent anti-Stokes Raman scattering light.

  According to the present invention, moisture in the electrode layer can be detected with high accuracy without interrupting the production of the electrode layer.

It is a front view which shows the structure of the manufacturing apparatus used by this embodiment. It is a flowchart explaining the manufacturing method of this embodiment. It is a graph which shows an example of the spectrum of the electrode layer from which the water | moisture content was detected. It is a graph which shows an example of the spectrum of the electrode layer from which the water | moisture content was not detected.

  Embodiments of an electrode layer inspection method and a battery manufacturing method according to the present invention will be described below with reference to the drawings.

  FIG. 1 shows the configuration of a manufacturing apparatus 1 used in an embodiment of the manufacturing method of the present invention. The manufacturing apparatus 1 manufactures the electrode layer 3 of the battery by roll-to-roll. That is, the manufacturing apparatus 1 unwinds and conveys the electrode foil 2 of the roll body, laminates a film of an electrode material on the electrode foil 2 being conveyed, winds up the sheet of the obtained electrode layer 3, and rolls the roll body. Has a production line. The manufacturing apparatus 1 performs an inspection to detect moisture in the electrode layer 3 while the sheet of the electrode layer 3 is being conveyed.

As shown in FIG. 1, the manufacturing apparatus 1 includes a transport mechanism 10 for the electrode foil 2, a coating apparatus 20, a drying apparatus 30, an inspection apparatus 40, and a control apparatus 50.
In the present embodiment, an example in which the electrode layer 3 of the lithium ion battery is manufactured by the manufacturing apparatus 1 will be described.

(Lithium ion battery)
The lithium ion battery is a secondary battery in which positive electrode layers 3 and negative electrode layers 3 are alternately stacked and enclosed in a case together with an electrolytic solution. A separator is provided between each electrode layer 3 of the positive electrode and the negative electrode in order to prevent a short circuit between the positive electrode and the negative electrode.

(Electrode layer)
The electrode layer 3 includes an electrode foil 2 and a positive electrode or negative electrode material film laminated on the electrode foil 2. The electrode material of the positive electrode and the negative electrode of a lithium ion battery each contains an electrode active material. A conventionally well-known substance can be used as an electrode active material of a positive electrode and a negative electrode.

  Examples of the positive electrode active material include lithium compounds such as lithium cobaltate, lithium nickelate, and lithium manganate, lithium-containing composite oxides including nickel, cobalt, manganese, etc., and olivine-type lithium such as olivine-type iron phosphate Compounds and the like. Examples of the electrode active material for the negative electrode include graphite, coke obtained by firing pitch, furfuryl alcohol resin, graphitizable carbonaceous material such as amorphous carbon obtained by firing low temperature phenol resin, titanic acid, etc. Examples thereof include lithium compounds such as lithium, porous silicon particles coated with a conductive material such as carbon, and silicon-based materials such as silicon oxycarbide (SiOC) composite materials.

  Examples of the electrode foil 2 include metals such as aluminum, copper, stainless steel, titanium, and metal foils of alloys. The types of the positive and negative electrode foils 2 may be the same or different. The thickness of the electrode foil 2 is usually 5 to 30 μm, and preferably 8 to 16 μm from the viewpoints of transportability and ease of winding.

(Transport mechanism)
The transport mechanism 10 includes an unwind roller 11, a take-up roller 12, and a plurality of transport rollers 13. The transport mechanism 10 unwinds the roll body of the electrode foil 2 by the unwinding roller 11 and transports the unwound sheet of the electrode foil 2 by each transport roller 13. Moreover, the conveyance mechanism 10 conveys the sheet | seat of the electrode layer 3 obtained by laminating | stacking the film | membrane of an electrode material on the electrode foil 2 with the conveyance roller 13, and the electrode layer 3 by which the detection of the water | moisture content was performed during conveyance. Is rolled up by a winding roller 12 to form a roll body.

(Applicator)
The coating device 20 applies electrode material ink on the electrode foil 2 unwound by the transport mechanism 10 to form a film of electrode material. The coating method is not particularly limited, and examples thereof include a die coating method, a roll coating method, a flow coating method, an ink jet method, a spray coating method, a dip coating method, a bar coating method, and a gravure printing method.

  In addition to the electrode active material described above, the electrode material ink may contain a binder, a solvent, a conductive auxiliary agent, and the like. Examples of the binder include polytetrafluoroethylene (PTFE) resin, polyvinylidene fluoride (PVdF) resin, and fluororubber. Examples of the solvent include protic polar solvents such as water and alcohols such as isopropanol, amides such as N-methylpyrrolidone and dimethyl sulfoxide, and aprotic polar solvents such as γ-butyrolactone. Examples of the conductive auxiliary agent include carbon materials such as carbon black.

(Drying device)
The drying device 30 is disposed downstream of the coating device 20 in the conveying direction of the electrode foil 2. The drying device 30 dries the electrode material film formed by the coating device 20. By drying, a sheet of the electrode layer 3 in which a film of an electrode material is laminated on the electrode foil 2 is obtained. In this embodiment, as shown in FIG. 1, the drying device 30 has a plurality of heaters 31 arranged in the transport direction, and dries by radiant heat from each heater 31. The drying method of the drying device 30 is not limited to this, and a known drying method such as blowing hot air with a dryer can be used.

(Inspection equipment)
The inspection device 40 is disposed downstream of the drying device 30 in the sheet conveyance direction of the electrode layer 3. The inspection device 40 detects moisture in the electrode layer 3 during conveyance of the dried electrode layer 3 sheet. The inspection device 40 detects moisture by coherent anti-Stokes Raman scattering (CARS) spectroscopy.
As illustrated in FIG. 1, the inspection apparatus 40 includes a light source 41, probes 42 and 43, a spectroscopic unit 44, a conversion unit 45, and a data processing unit 46.

  The light source 41 generates two laser beams having different angular frequencies. As the light source 41, a pulse laser light source or the like can be used. Of the two laser beams, the laser beam having a high angular frequency (ω1) is called pump light, and the laser beam having a low angular frequency (ω2) is called Stokes light. The probe 42 guides and condenses two laser beams onto the electrode layer 3 to be measured. When the angular frequency difference (ω1, ω2) between the pump light and the Stokes light matches the frequency unique to each molecule in the electrode layer 3, a dipole moment of the matched molecule is induced, and scattered light is generated. Of this scattered light, light (ω3) having an angular frequency of (2ω1-ω2) is CARS light.

  Scattered light from the film is received by the probe 43 and guided to the spectroscopic unit 44. The spectroscopic unit 44 extracts CARS light from the scattered light received by the probe 43 and separates it for each wavelength. The conversion unit 45 outputs an electrical signal indicating the intensity of light of each wavelength obtained by the spectroscopic unit 44. As the conversion unit 45, for example, a photoelectric conversion element such as a charge coupled device (CCD) or an intensified CCD (ICCD) can be used. The data processing unit 46 creates a spectrum of CARS light based on the electrical signal output from the conversion unit 45. Further, the data processing unit 46 detects a vibration peak of water molecules from the created spectrum. As the data processing unit 46, a computer having a processor such as a CPU (Central Processing Unit) and a memory such as a hard disk can be used.

(Control device)
The control device 50 controls operations of the transport mechanism 10, the coating device 20, and the drying device 30. For example, the control device 50 can control the transport speed by the transport mechanism 10, the transport start timing, the coating amount by the coating device 20, the coating timing, the drying temperature by the drying device 30, the drying time, and the like. As the control device 50, for example, a computer including a processor, a memory, and the like can be used.

FIG. 2 is a flowchart illustrating an inspection method for an electrode layer 3 of a lithium ion battery and a method for manufacturing a lithium ion battery, which are performed in the manufacturing apparatus 1 as an embodiment of the present invention.
In the manufacturing apparatus 1, a roll body of the electrode foil 2 is set in advance on the unwinding roller 11, and the sheet of the electrode foil 2 is wound from the unwinding roller 11 to the winding roller 12.

  When the production of the electrode layer 3 is started in the production apparatus 1, as shown in FIG. 2, the electrode foil 2 of the roll body is sequentially unwound and conveyed by the conveyance mechanism 10 (step S1). On one surface of the electrode foil 2 being conveyed, the electrode material ink is applied by the coating device 20 to form a film of the electrode material (step S2). The coating amount of the electrode material ink is adjusted according to the conveying speed of the electrode foil 2 and the drying conditions so that a film having a desired thickness can be obtained after drying. Next, the film on the electrode foil 2 is dried in the drying device 30 (step S3). By drying, moisture and solvent in the film are evaporated, and a sheet of the electrode layer 3 in which the film of the electrode material is laminated on the electrode foil 2 is obtained.

  After drying, an inspection for detecting moisture in the electrode layer 3 is performed in the inspection device 40 (step S4). Specifically, pulse laser light emitted from the light source 41 is irradiated to the electrode layer 3 by the probe 42. Scattered light generated in the electrode layer 3 is received by the probe 42 and guided to the spectroscopic unit 44. In the spectroscopic unit 44, the CARS light is extracted from the scattered light, and further separated for each wavelength. The light of each wavelength is converted into an electric signal indicating the light intensity by the converter 45, and a spectrum is created from the electric signal by the data processor 46. In the data processing unit 46, the spectrum is analyzed, and the vibration peak of the water molecule having an intensity equal to or higher than the threshold is detected. After the inspection, the sheet of the electrode layer 3 is taken up by the take-up roller 12 to form a roll body of the electrode layer 3.

FIG. 3 shows an example of the spectrum of the electrode layer 3 in which moisture is detected. FIG. 4 shows an example of the spectrum of the electrode layer 3 in which moisture was not detected.
When the electrode layer 3 contains moisture, as shown in FIG. 3, in the spectrum obtained by CARS spectroscopy, water molecules are present in the vicinity of 3400 cm ⁻¹ as a broad band due to OH stretching and antisymmetric stretching motions. The vibration peak _POH is observed. CARS light, since the intensity than the scattered light measured in a typical Raman spectroscopy is large, the water content in the electrode layer 3 is also a small amount, detecting the vibration peak P _OH of water molecules with high precision be able to. When thoroughly dried to the moisture of the electrode layer 3 is removed, as shown in FIG. 4, spectrum vibrational peak P _OH is not observed in the water molecules shown in Figure 3 is obtained.

Therefore, the data processing unit 46, for example, when a vibration peak with a certain intensity or more is detected within a certain range centered on 3400 cm ⁻¹ (for example, 3000 to 3600 cm ⁻¹ ), the vibration peak is a water molecule. it is determined that the vibration peak P _OH, it is possible to detect the water.

  In step S4 for detecting moisture, the inspection apparatus 40 can detect moisture at a plurality of different positions in the sheet conveyance direction or width direction of the electrode layer 3. The width direction is a direction orthogonal to the conveyance direction on the sheet. Thereby, quality assurance in the length direction or width direction of the sheet of the electrode layer 3 is possible. The inspection apparatus 40 may detect moisture at a plurality of positions in both the transport direction and the width direction.

  Since the sheet of the electrode layer 3 is conveyed, the inspection apparatus 40 can perform detection at a plurality of positions different in the conveyance direction of the sheet of the electrode layer 3 by performing detection at an arbitrary interval. In addition, the inspection apparatus 40 can detect moisture at a plurality of arbitrary positions by scanning the probes 42 and 43 in the width direction. The inspection apparatus 40 has a plurality of sets of probes 42 and 43 arranged at a plurality of positions in the width direction, and can detect moisture at each position.

  In step S4 for detecting moisture, the inspection device 40 can detect the amount of moisture in the electrode layer 3 by analyzing the intensity of the vibration peak of water molecules. For example, the data processing unit 46 creates a spectrum in which the moisture content in the electrode layer 3 is known, and obtains a function representing the relationship between the intensity of the vibration peak of water molecules in the spectrum and the moisture content. From this function, the data processor 46 obtains the amount of water corresponding to the intensity of the vibration peak of water molecules observed in the spectrum of the electrode layer 3 to be examined.

  When detecting the amount of moisture in step S4 for detecting moisture, the inspection apparatus 40 detects the amount of moisture at a plurality of different positions in the sheet width direction of the electrode layer 3, and the amount of moisture detected at each position. The average value of can be output. Thereby, the average water content in the width direction can be grasped.

  When moisture is detected in the inspection device 40 (step S5: YES), the drying conditions are adjusted by the control device 50 (step S6). In step S6 for adjusting the drying conditions, the control device 50 can execute at least one of adjustment for increasing the drying temperature in the drying device 30 and adjustment for increasing the drying time. By the adjustment, water in the produced electrode layer 3 can be sufficiently removed.

  For example, the control device 50 can be adjusted to increase the drying temperature by increasing the temperature of the heater 31 by 1 ° C. The control device 50 can adjust the drying time to be longer by turning on the power and increasing the number of heaters 31 used for drying among the plurality of heaters 31 arranged in the transport direction. Specifically, two heaters 31 are used initially for drying, and the number of heaters 31 is increased to three when moisture is detected. Further, the control device 50 can adjust the drying time to be longer by reducing the transport speed of the electrode foil 2 by the transport mechanism 10. In this case, the control device 50 also performs adjustment to reduce the coating amount of the coating device 20 so that the thickness of the electrode material film does not change. Only one of the adjustment of the drying temperature and the adjustment of the drying speed may be performed, or both may be performed.

  In step S <b> 6 for adjusting the drying conditions of the electrode layer 3, at least one of the drying temperature to be increased and the drying time to be lengthened is determined by the control device 50 according to the amount of water in the electrode layer 3 detected by the inspection device 40. can do. Thereby, the water | moisture content in the electrode layer 3 can fully be removed, suppressing the damage of the film | membrane of the electrode material by drying.

  For example, when the water content is equal to or less than the threshold value, the control device 50 can determine the increase in the drying temperature as 1 ° C., or can determine the extension time of the drying time as 1 second. On the other hand, when the moisture content exceeds the threshold value, the control device 50 can determine the increase in the drying temperature as 2 ° C. or can determine the extension time of the drying time as 2 seconds. If a plurality of threshold values are used, it is possible to adjust the drying temperature and the drying time in a plurality of stages.

  As described above, according to the manufacturing method of the present embodiment, since moisture in the electrode layer 3 is detected by CARS spectroscopy, inspection can be performed in a non-contact manner. In addition, since CARS spectroscopy has a higher signal intensity than general Raman spectroscopy, it is possible to detect a very small amount of moisture in the electrode layer 3 with high accuracy. Therefore, the water in the electrode layer 3 can be detected with high accuracy without interrupting the production of the electrode layer 3, and the high-quality electrode layer 3 can be produced with high production efficiency. By using the high-quality electrode layer 3, the quality of the battery is improved, and the overall production efficiency of the battery is also improved.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the scope of the present invention.
For example, a battery in which the electrode layers of the positive electrode and the negative electrode are alternately laminated, and other batteries such as a nickel metal hydride battery, a nickel cadmium battery, etc., as long as the electrode layer is easily deteriorated by moisture The present invention can also be implemented.

DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus, 2 ... Electrode foil, 3 ... Electrode layer, 10 ... Conveyance mechanism, 20 ... Coating apparatus, 30 ... Drying apparatus, 40 ... Inspection apparatus, 41 ... Light source, 42, 43 ... Probe, 44 ... Spectral unit, 45 ... Conversion unit, 46 ... Data processing unit, 50 ... Control device

Claims (7)

A method for inspecting a battery electrode layer,
In a production line in which a roll body of electrode foil is unwound and conveyed, a film of an electrode material is laminated on the electrode foil, and a sheet of the obtained electrode layer is wound to form a roll body, the sheet of the electrode layer Detecting the moisture in the electrode layer during transport of (S4),
In the step of detecting moisture (S4), laser light is emitted to the electrode layer, coherent anti-Stokes Raman scattered light is received from the electrode layer, and the spectrum of the received coherent anti-Stokes Raman scattered light is received. Detect vibration peaks of water molecules,
Inspection method of electrode layer. In the step of detecting the moisture (S4), moisture is detected at each of a plurality of different positions in the sheet conveyance direction or width direction of the electrode layer.
The electrode layer inspection method according to claim 1. In the step of detecting moisture (S4), the intensity of the vibration peak of water molecules in the spectrum is analyzed to detect the amount of moisture in the electrode layer.
The inspection method of the electrode layer according to claim 1 or 2. In the step of detecting the moisture (S4), the moisture amount is detected at a plurality of different positions in the width direction of the electrode layer sheet, and an average value of the moisture amount detected at each position is output.
The method for inspecting an electrode layer according to claim 3. A method for producing a battery having an electrode layer,
Unwinding and conveying the roll of electrode foil (S1);
Applying an electrode material ink on the electrode foil to form a film of the electrode material (S2);
Drying the electrode material film to obtain a sheet of the electrode layer (S3);
Detecting the moisture in the electrode layer during the conveyance of the sheet of the electrode layer (S4);
Winding the sheet of the electrode layer after detecting the moisture to form a roll body;
If moisture in the electrode layer is detected, adjusting the drying conditions of the electrode material film (S6),
In the step of detecting moisture (S4), laser light is emitted to the electrode layer, coherent anti-Stokes Raman scattered light is received from the electrode layer, and the spectrum of the received coherent anti-Stokes Raman scattered light is received. Detect vibration peaks of water molecules,
Battery manufacturing method. In the step (S6) of adjusting the drying condition of the electrode material film, at least one of adjustment for increasing the drying temperature of the electrode material film and adjustment for increasing the drying time of the electrode material film is executed. ,
The method for producing a battery according to claim 5. In the step of detecting the water (S4), the intensity of the vibration peak of the water molecule is analyzed to detect the amount of water in the electrode layer,
In the step of adjusting the drying condition of the electrode material film (S6), at least one of the drying temperature to be increased and the drying time to be increased is determined according to the amount of water detected in the electrode layer.
The battery manufacturing method according to claim 6.

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