electrode

Abstract

An electrode 1 comprises a resin film 2, a metal ground layer 3, and a conductive carbon layer 4 having sp2 bonds and sp3 bonds in order toward one side in the thickness direction. The ratio of the number of sp3-bonded atoms to the sum of the number of sp3-bonded atoms and the number of sp2-bonded atoms is at least 0.25. The thickness of the metal ground layer 3 is less than 50 nm.

Description

[Technical field]

[0001] The present invention relates to an electrode. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an electrode has been known in which a thin underlayer and a thin carbon film are laminated in this order on one side of a plastic substrate (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2016 / 013478 issue Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there is a demand for electrodes with even higher sensitivity. 3 Number of atoms bonded and sp 2 Number of atoms bonded and sp 3 A tentative plan is to increase the ratio of the number of bonded atoms to widen the potential window.

[0005] However, sp 3 If the ratio of the number of bonded atoms is increased, the carbon thin film becomes hard, which causes the electrode to warp.

[0006] The present invention provides an electrode that can widen the potential window while suppressing the amount of warping. [Means for solving the problem]

[0007] The present invention (1) is a resin film, a metal underlayer, and a sp 2 Bonds and sp 3 A conductive carbon layer having a bond is provided in order toward one side in the thickness direction, and sp 3 Number of atoms bonded and sp 2sp for the sum of the number of atoms bonded 3 The ratio of the number of bonded atoms is 0.25 or more, and the thickness of the metal underlayer is less than 50 nm.

[0008] The present invention (2) includes the electrode according to (1), in which the material of the metal underlayer is at least one metal element selected from the group consisting of titanium, tantalum, chromium, molybdenum, and tungsten.

[0009] The present invention (3) includes the electrode according to (1) or (2), in which the conductive carbon layer has a thickness of 0.2 nm or more and 50 nm or less.

[0010] The present invention (4) includes the electrode according to any one of (1) to (3), in which the material of the resin film is polyethylene terephthalate. Effect of the Invention

[0011] The electrode of the present invention can widen the potential window while suppressing the amount of warping. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 shows a cross-sectional view of one embodiment of an electrode of the present invention. [Diagram 2] FIG. 2 is a perspective view illustrating the measurement of the curl amount in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <One embodiment> One embodiment of the electrode of the present invention will be described with reference to FIG.

[0014] (electrode 1) 1, electrode 1 has a predetermined thickness and has a film shape (including a sheet shape) extending in a plane direction perpendicular to the thickness direction. Electrode 1 has one surface in the thickness direction that is flat along the plane direction, and the other surface that is spaced apart from the one surface in the thickness direction.

[0015] Specifically, the electrode 1 comprises a resin film 2, a metal base layer 3 disposed on one surface in the thickness direction of the resin film 2, and a conductive carbon layer 4 disposed on one surface in the thickness direction of the metal base layer 3. That is, the electrode 1 comprises the resin film 2, the metal base layer 3, and the conductive carbon layer 4 in this order on one side in the thickness direction. Preferably, the electrode 1 comprises the resin film 2, the metal base layer 3, and the conductive carbon layer 4. Each layer will be described in detail below.

[0016] (Resin film 2) The resin film 2 forms the other thickness-wise surface of the electrode 1. The resin film 2 has a film shape extending in the planar direction. The resin film 2 is a base film of the electrode 1.

[0017] The resin film 2 has, for example, flexibility. Specifically, the resin film 2 has a folding endurance test (JIS C 5016 (1994)) of, for example, 250 times or more, preferably 500 times or more. If the folding endurance test result of the resin film 2 is equal to or more than the above-mentioned lower limit, the resin film 2 has excellent flexibility.

[0018] Examples of materials for the resin film 2 include polyester resins (e.g., polyethylene terephthalate, polyethylene naphthalate), acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins (e.g., polycycloolefin polymers), (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, polyphenylene sulfide resins, etc. Polyester resins are preferred, and polyethylene terephthalate is more preferred.

[0019] The thickness of the resin film 2 is not particularly limited and is, for example, 2 μm or more, preferably 20 μm or more, and for example, 1000 μm or less, preferably 500 μm or less.

[0020] (metal base layer) The metal underlayer 3 is disposed on one surface in the thickness direction of the resin film 2. Specifically, the metal underlayer 3 is in contact with the entire one surface in the thickness direction of the resin film 2. The metal underlayer 3 extends in the planar direction. The metal underlayer 3 is an intermediate layer located between the resin film 2 and the conductive carbon layer 4.

[0021] Examples of materials for the metal underlayer 3 include Group 4 metal elements such as titanium and zirconium, Group 5 metal elements such as vanadium, niobium, and tantalum, Group 6 metal elements such as chromium, molybdenum, and tungsten, Group 7 metal elements such as manganese, Group 8 metal elements such as iron, Group 9 metal elements such as cobalt, Group 10 metal elements such as nickel and platinum, Group 11 metal elements such as gold, Group 12 metal elements such as zinc, Group 13 metal elements such as aluminum and gallium, and Group 14 metal elements such as germanium and tin. These materials can be used alone or in combination. Examples of materials for the metal underlayer 3 are preferably titanium, tantalum, chromium, molybdenum, and tungsten, and from the viewpoint of chemical stability, more preferably titanium and tungsten, and even more preferably tungsten.

[0022] The thickness of the metal underlayer 3 is less than 50 nm, preferably 45 nm or less, more preferably 40 nm or less, and further preferably 35 nm or less. If the thickness of the metal underlayer 3 exceeds the above upper limit, the electrode 1 will warp.

[0023] The thickness of the metal underlayer 3 is, for example, 0.1 nm or more, preferably 1 nm or more, and more preferably 5 nm or more. When the thickness of the metal underlayer 3 is equal to or more than the above-mentioned lower limit, the sensing stability is excellent.

[0024] The thickness of the metal underlayer 3 is determined by X-ray diffraction method, which will be described in detail in the Examples.

[0025] (Conductive carbon layer 4) The conductive carbon layer 4 has electrical conductivity. The conductive carbon layer 4 forms one surface in the thickness direction of the electrode 1. The conductive carbon layer 4 is disposed on one surface in the thickness direction of the metal base layer 3. Specifically, the conductive carbon layer 4 is in contact with the entire one surface in the thickness direction of the metal base layer 3. The conductive carbon layer 4 extends in the planar direction.

[0026] The conductive carbon layer 4 is made of sp 2 Carbon with bonds and sp 3 The conductive carbon layer 4 mainly contains carbon having bonds. That is, the conductive carbon layer 4 is a layer having a graphite structure and a diamond structure. This provides the conductive carbon layer 4 with good conductivity, and sufficiently improves the sensitivity to the measurement target.

[0027] The conductive carbon layer 4 may contain, for example, oxygen in addition to carbon. Specifically, for example, oxygen is contained on one surface in the thickness direction of the conductive carbon layer 4. The concentration ratio of oxygen to carbon (O / C) on one surface in the thickness direction of the conductive carbon layer 4 is not particularly limited and is, for example, 0.001 or more and, for example, 0.2 or less.

[0028] Furthermore, the conductive carbon layer 4 is permissible to contain trace amounts of unavoidable impurities other than oxygen.

[0029] In the conductive carbon layer 4, sp 3 Number of atoms bonded and sp 2 sp for the sum of the number of atoms bonded 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) is 0.25 or more, preferably 0.30 or more, and more preferably 0.35 or more. 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) falls below the above-mentioned lower limit, the potential window of the electrode 1 cannot be widened.

[0030] Also, sp3 Number of atoms bonded and sp 2 sp for the sum of the number of atoms bonded 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) is, for example, 0.9 or less, preferably 0.6 or less. 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) is equal to or less than the above upper limit, the conductivity of the conductive carbon layer 4 can be ensured, and a decrease in the detection sensitivity of the electrode 1 can be suppressed.

[0031] sp 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) is a spectrum obtained by measuring one surface in the thickness direction of the conductive carbon layer 4 by X-ray photoelectron spectroscopy. 2 Bond peak intensity and sp 3 Calculations are based on peak binding intensities.

[0032] The surface resistance of the conductive carbon layer 4 on one surface in the thickness direction is, for example, 1.0×10 4 Ω / □ or less, preferably 1.0×10 3 It is less than Ω / □.

[0033] The thickness of the conductive carbon layer 4 is, for example, 0.1 nm or more, preferably 0.2 nm or more, and 100 nm or less, preferably 50 nm or less. When the thickness of the conductive carbon layer 4 is equal to or more than the above-mentioned lower limit, stable electrode characteristics can be exhibited. On the other hand, when the thickness of the conductive carbon layer 4 is equal to or less than the above-mentioned upper limit, the electrode 1 has excellent flexibility and is easy to handle. The thickness of the conductive carbon layer 4 is determined by X-ray diffraction. The X-ray diffraction method will be described in detail in the Examples.

[0034] (Physical properties of electrode 1) The curl amount of this electrode 1 is small, specifically, the curl amount of the electrode 1 cut into a rectangular shape of 100 mm x 100 mm is, for example, 40 mm or less, preferably 30 mm or less, more preferably 20 mm or less, even more preferably 15 mm or less, and most preferably 0 mm. As shown in FIG. 2, the electrode 1 cut to the above size is placed on the upper surface of a flat plate 5. The temperature at this time is 23°C. Thereafter, when the four corners 6 are warped up, the amount of warping (height from the flat plate) of each is measured, and the curl amount is obtained as the average of the measured values. The smaller the curl amount of the electrode 1, the more the amount of warping of the electrode 1 is suppressed.

[0035] The thickness of the electrode 1 is the total thickness of the resin film 2, the metal underlayer 3 and the conductive carbon layer 4, and is specifically, for example, 2 μm or more, preferably 20 μm or more, and for example, 1000 μm or less, preferably 500 μm or less.

[0036] (Method of Manufacturing Electrode 1) Next, a method for manufacturing the electrode 1 will be described.

[0037] In this method, first, a resin film 2 is prepared.

[0038] Next, the metal underlayer 3 is formed on one surface in the thickness direction of the resin film 2. The method for forming the metal underlayer 3 is not particularly limited, and examples thereof include metal film forming methods such as dry methods and wet methods such as plating. A dry method is preferably used. Examples of the dry method include PVD (physical vapor deposition) and CVD (chemical vapor deposition), and a preferred example is PVD. Examples of the PVD method include sputtering, vacuum deposition, laser deposition, and ion plating (arc deposition, etc.). A preferred example is sputtering. The target in the sputtering method is, for example, the material of the metal underlayer 3. Examples of the sputtering gas include inert gases such as Ar and Xe. The pressure in the sputtering is, for example, 1 Pa or less. The film forming temperature is, for example, 50° C. or more, and, for example, 200° C. or less.

[0039] Thereafter, the conductive carbon layer 4 is formed on one surface in the thickness direction of the metal underlayer 3. The method for forming the conductive carbon layer 4 may be, for example, a dry method. Examples of the dry method include a PVD method (physical vapor deposition method) and a CVD method (chemical vapor deposition method), and preferably, the PVD method. Examples of the PVD method include a sputtering method, a vacuum deposition method, a laser deposition method, an ion plating method (such as an arc deposition method), and the like. Preferably, the sputtering method is used.

[0040] Examples of sputtering methods include unbalanced magnetron sputtering (UBM sputtering), high-power pulse sputtering, electron cyclotron resonance sputtering, RF sputtering, DC sputtering (DC magnetron sputtering, etc.), DC pulse sputtering, and ion beam sputtering. 3 From the viewpoint of easily setting the ratio of the numbers of bonded atoms within the desired range described above and of improving the film formation rate and adhesion to the metal underlayer 3, UBM sputtering is more preferable.

[0041] The target in the sputtering method may be, for example, sintered carbon. The sputtering gas may be, for example, an inert gas. The pressure in the sputtering is, for example, 1 Pa or less. The film formation temperature is, for example, 0° C. or more, for example, 100° C. or less.

[0042] The conductive carbon layer 4 may be subjected to known surface treatments such as ion milling, ion bombardment, electrolytic polishing, and voltage application cycles (2 to 20 cycles) as required.

[0043] sp 3 In order to set the ratio of the numbers of bonded atoms within the above-mentioned desired range, the above-mentioned sputtering conditions and surface treatment are appropriately selected.

[0044] As a result, an electrode 1 is obtained which includes the resin film 2, the metal base layer 3, and the conductive carbon layer 4 in that order on one side in the thickness direction.

[0045] (Use of electrode 1) The electrode 1 can be used as various electrodes, and preferably can be used as an electrode for electrochemical measurement to perform an electrochemical measurement method, specifically, as a working electrode (working electrode) to perform cyclic voltammetry (CV) or a working electrode (working electrode) to perform anodic stripping voltammetry (ASV).

[0046] (Effects of one embodiment) And according to this electrode 1, sp 3 Number of atoms bonded and sp 2 sp for the sum of the number of atoms bonded 3 Since the ratio of the number of bonded atoms is 0.25 or more, the potential window can be widened.

[0047] On the other hand, in this electrode 1, since the thickness of the metal underlayer 3 is less than 50 nm, the internal stress that imparts (applies) a force that distorts the resin film 2 is reduced in the metal underlayer 3, and as a result, the amount of warping is suppressed.

[0048] Therefore, this electrode 1 can widen the potential window while suppressing the amount of warping.

[0049] Furthermore, in this electrode 1, if the material of the metal underlayer 3 is at least one metal element selected from the group consisting of titanium, tantalum, chromium, molybdenum, and tungsten, sufficient adhesion between the resin film 2 and the conductive carbon layer 4 can be ensured.

[0050] Furthermore, when the thickness of the conductive carbon layer 4 is 0.2 nm or more, stable electrode characteristics can be exhibited. On the other hand, when the thickness of the conductive carbon layer 4 is 50 nm or less, the flexibility is excellent, and therefore the handling properties of the electrode 1 become good.

[0051] (Modification) As shown in Fig. 1, in one embodiment, the electrode 1 includes one resin film 2, one metal base layer 3, and one conductive carbon layer 4. On the other hand, the electrode 1 may include one resin film 2, two metal base layers 3, and two conductive carbon layers 4. That is, the electrode 1 may include two metal base layers 3 and two conductive carbon layers 4 for one resin film 2. In this case, the conductive carbon layer 4, the metal base layer 3, the resin film 2, the metal base layer 3, and the conductive carbon layer 4 are arranged in this order in the thickness direction.

[0052] Moreover, in order to form the metal underlayer 3 with a desired thickness, the above-mentioned metal film formation method can be carried out multiple times. EXAMPLES

[0053] The present invention will be described in more detail below with reference to examples and comparative examples. The present invention is not limited to the examples and comparative examples. The specific numerical values ​​of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (a numerical value defined as "equal to or less than") or lower limit (a numerical value defined as "equal to or more than" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Form for carrying out the invention".

[0054] (Method of Measuring Thickness of Metal Underlayer 3 and Conductive Carbon Layer 4) First, the method for measuring the thickness of the metal underlayer 3 and the thickness of the conductive carbon layer 4 is described below. Specifically, the measurement principle is X-ray reflectivity, and X-ray reflectivity is measured under the following <measurement conditions> using a powder X-ray diffractometer (manufactured by Rigaku Corporation, "RINT-2200"), and the obtained measurement data is analyzed using analysis software (manufactured by Rigaku Corporation, "GXRR3") to calculate the thickness of the metal underlayer 3 and the thickness of the conductive carbon layer 4 in each of the examples and comparative examples.

[0055] For the analysis, a three-layer model consisting of a resin film 2, a metal base layer 3, and a conductive carbon layer 4 was adopted under the following <analysis conditions>, and the target thickness and density of the metal base layer 3 were 19.30 g / cm 3 are input as initial values, and the target thickness and density of the conductive carbon layer 4 are 19.5 g / cm 3 was input as an initial value. Then, least squares fitting with the measured values ​​was performed to calculate the thickness of the metal underlayer 3 and the thickness of the conductive carbon layer 4.

[0056] <Measurement conditions> Measurement equipment: Powder X-ray diffraction equipment (Rigaku Corporation, "RINT-2000") Light source: Cu-Kα line (wavelength: 1,5418Å), 40kV, 40mA Optical system: Parallel beam optical system Divergence slit: 0.05mm Receiving slit: 0.05 mm Monochromatization and collimation: Using multi-layer Goebel mirrors Measurement mode: θ / 2θ scan mode Measurement range (2θ): 0.3 to 2.0°

[0057] <Analysis conditions> Analysis software: Rigaku's "GXRR3" Analysis method: Least squares fitting Analysis range (2θ): 2θ=0.3~2.0°

[0058] Example 1 (Preparation of resin film 2) A resin film 2 made of polyethylene terephthalate having a thickness of 50 μm was prepared.

[0059] (Formation of Metal Underlayer 3) Next, a metal underlayer 3 made of tungsten was formed by sputtering on one surface in the thickness direction of the resin film 2. The thickness of the metal underlayer 3 was 40 nm. The conditions for the sputtering are described below.

[0060] Target material: Tungsten Argon gas pressure: 0.6 Pa Target power: 400W Film forming roll temperature: 120℃

[0061] (Formation of Conductive Carbon Layer 4) Thereafter, a conductive carbon layer 4 was formed by UBM sputtering on one surface in the thickness direction of the metal underlayer 3. The thickness of the conductive carbon layer 4 was 30 nm. The conditions for the UBM sputtering are described below.

[0062] Target material: sintered carbon Argon gas pressure: 0.8 Pa Target power: 400W Film forming roll temperature: 30℃ DC bias (between metal substrate 3 and target material): 75V

[0063] Thereafter, a voltage application cycle in which a voltage was applied to the conductive carbon layer 4 was alternately changed between 0 V and 2.3 V was carried out 10 times.

[0064] In this way, the electrode 1 was obtained.

[0065] Example 2 An electrode 1 was obtained by the same treatment as in Example 1. However, the thickness of the metal underlayer 3 was changed from 40 nm to 30 nm.

[0066] Example 3 An electrode 1 was obtained by the same treatment as in Example 1. However, the thickness of the metal underlayer 3 was changed from 40 nm to 10 nm.

[0067] Example 4 An electrode 1 was obtained by the same treatment as in Example 1. However, the thickness of the metal underlayer 3 was changed from 40 nm to 30 nm, and the DC bias was changed from 75 V to 30 V.

[0068] Comparative Example 1 An electrode 1 was obtained by the same treatment as in Example 1. However, the thickness of the metal underlayer 3 was changed from 40 nm to 50 nm.

[0069] Comparative Example 2 An electrode 1 was obtained by the same treatment as in Example 1. However, the thickness of the metal underlayer 3 was changed from 40 nm to 50 nm. Meanwhile, no DC bias was applied, and no voltage application cycle was performed.

[0070] Example 5 An electrode 1 was obtained by the same process as in Example 2. However, chromium was used as the target material in forming the metal underlayer 3. In other words, the material of the metal underlayer 3 was changed from tungsten to chromium.

[0071] Comparative Example 3 An electrode 1 was obtained by the same treatment as in Example 5. However, the thickness of the metal underlayer 3 was changed from 30 nm to 50 nm.

[0072] Example 6 An electrode 1 was obtained by the same process as in Example 2. However, molybdenum was used as the target material in forming the metal underlayer 3. In other words, the material of the metal underlayer 3 was changed from tungsten to molybdenum.

[0073] Comparative Example 4 An electrode 1 was obtained by the same treatment as in Example 6. However, the thickness of the metal underlayer 3 was changed from 30 nm to 50 nm.

[0074] Example 7 An electrode 1 was obtained by the same process as in Example 2. However, tantalum was used as the target material in forming the metal underlayer 3. In other words, the material of the metal underlayer 3 was changed from tungsten to tantalum.

[0075] Comparative Example 5 An electrode 1 was obtained by the same treatment as in Example 7. However, the thickness of the metal underlayer 3 was changed from 30 nm to 50 nm.

[0076] Example 8 An electrode 1 was obtained by the same process as in Example 2. However, titanium was used as the target material in forming the metal underlayer 3. In other words, the material of the metal underlayer 3 was changed from tungsten to titanium.

[0077] Tables 1 and 2 show the material of the metal underlayer 3, the thickness of the metal underlayer 3, and the thickness of the conductive carbon layer 4 in Examples 1 to 8 and Comparative Examples 1 to 5.

[0078] (evaluation) The following items were evaluated, and the results are shown in Tables 1 and 2.

[0079] (sp 3 Number of atoms bonded and sp 2 sp for the sum of the number of atoms bonded 3 (ratio of the number of bonded atoms) X-ray photoelectron spectroscopy was performed on one surface in the thickness direction of the conductive carbon layer 4 under the following <measurement conditions>. In the spectrum obtained by this, sp 2 Bond peak intensity and sp 3 Based on the peak intensity of the bond, sp 2 Number of carbon atoms bonded and sp 3 The number of carbon atoms bonded to the atom is expressed as sp 3 The ratio of the number of carbon atoms in the bond (sp 3 / sp 3 +sp 2 ) was calculated.

[0080] <Measurement conditions> Measuring device: X-ray photoelectron spectroscopy (XPS) device (manufactured by Shimadzu Corporation, product name "AXIS Nova") X-ray source: Rowland circle 500 mm diameter monochromator equipped AlKα (1486.6 eV), 15 kV, 10 mA Photoelectron spectrometer: Orbit radius 165 mm, electrostatic double hemispherical analyzer / spherical mirror analyzer hybrid type Detector: Delay Line Detector (DLD) system Energy resolution: Ag3d5 / 2 photoelectron peak half-width 0.48 eV or less Charge neutralization: Uniform low-energy electron irradiation

[0081] (Curl amount) First, the electrode 1 was cut to a size of 100 mm in length and 100 mm in width. Next, as shown in FIG. 2, the electrode 1 was placed on the upper surface of a flat plate 5 with the resin film 2 facing downward. The temperature at this time was 23° C. After one minute had passed, the four corners 6 had warped up, and the amount of warping at each corner (the height from the flat plate 5) was measured, and the curl amount was calculated as the average of the measured amounts. From the amount of curl, the suppression of the amount of warping was evaluated according to the following criteria.

[0082] ◯: The curl amount was 40 mm or less. ×: The curl amount exceeded 40 mm.

[0083] [Table 1]

[0084] [Table 2]

[0085] The above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be interpreted as being limited. Modifications of the present invention that are obvious to those skilled in the art are included in the scope of the following claims. [Industrial Applicability]

[0086] The electrodes are used in electrochemical measurement electrodes for carrying out electrochemical measurements. [Explanation of symbols]

[0087] 1 electrode 2. Resin film 3 Metal base layer 4 Conductive carbon layer

Claims

1. A resin film; A metal underlayer; s.p. ２ Bonds and sp ３ A conductive carbon layer having a bond are provided in order toward one side in the thickness direction, s.p. ３ Number of atoms bonded and sp ２ sp relative to the sum of the number of bonded atoms ３ The ratio of the number of bonded atoms is 0.3 or more and 0.4 or less, The thickness of the metal underlayer is 30 nm or more and 40 nm or less, An electrode, wherein the material of the metal underlayer is at least one metal element selected from the group consisting of zirconium, vanadium, niobium, tantalum, molybdenum, manganese, iron, cobalt, nickel, platinum, gold, zinc, gallium, germanium, and tin.

2. The electrode according to claim 1 , wherein the conductive carbon layer has a thickness of 0.2 nm or more and 50 nm or less.

3. The electrode according to claim 1 , wherein the material of the resin film is polyethylene terephthalate.

4. The electrode according to claim 2 , wherein the material of the resin film is polyethylene terephthalate.

Images