electrode

Abstract

To provide an electrode capable of suppressing damage to a conductive carbon layer even when curved. The electrode includes a resin film, a metal underlayer, and a conductive carbon layer in this order in the thickness direction. 2 Bonds and sp 3 sp bonds. 3 Number of atoms bonded and sp 2 sp for the sum of the number of bonded atoms 3 The ratio of the number of bonded atoms is 0.10 or more. The conductive carbon layer has a density of 4.0 g / cm 3 It has the following density:

Description

[Technical Field]

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

[0002] An electrode including a film substrate and a carbon thin film is known (see, for example, Patent Document 1 below). The carbon thin film described in Patent Document 1 contains diamond-like carbon. In this case, the carbon thin film is sp 3 Includes joins. [Prior art documents] [Patent documents]

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

[0004] Electrodes may be curved depending on the application and purpose. However, when the electrode described in Patent Document 1 is curved, cracks tend to occur in the carbon thin film because the carbon thin film is relatively brittle. This causes a problem of increased resistance in the electrode.

[0005] The present invention provides an electrode that can suppress damage to the conductive carbon layer even when bent. [Means for solving the problem]

[0006] The present invention (1) is an electrode having a resin film and a conductive carbon layer in this order in the thickness direction, and the conductive carbon layer is sp 3 The electrode has a bond, and when heated at 150°C for 1 hour, the heat shrinkage rate is -0.2% or more and 0.2% or less.

[0007] In the present invention (2), the conductive carbon layer is sp 2Further having a bond, sp 3 Number of atoms bonded and sp 2 sp for the sum of the number of bonded atoms 3 The electrode according to (1) includes an electrode in which the ratio of the number of bonded atoms is 0.10 or more.

[0008] In the present invention (3), the conductive carbon layer has a density of 1.8 g / cm 3 The electrode according to (1) or (2) has a density of at least 1000 kJ / cm2. [Effects of the Invention]

[0009] The electrode of the present invention can suppress damage to the conductive carbon layer even when bent, and can suppress the rate of increase in resistance before and after bending. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of one embodiment of the electrode of the present invention. [Figure 2] FIG. 2 shows a modified example of the electrode. [Figure 3] FIG. 3 shows a modified example of the electrode. [Figure 4] FIG. 4 shows Test A for measuring the rate of increase in resistance. [Figure 5] Figure 5 shows Test B for measuring the rate of increase in resistance. DETAILED DESCRIPTION OF THE INVENTION

[0011] <One embodiment> One embodiment of the electrode of the present invention will be described with reference to FIG.

[0012] (electrode 1) As shown in Figure 1, electrode 1 has a predetermined thickness. Electrode 1 has a film shape (including a sheet shape) extending in a plane direction. The plane direction is perpendicular to the thickness direction. Electrode 1 has one surface and the other surface spaced apart from each other in the thickness direction.

[0013] (Thermal shrinkage rate of electrode 1) The thermal shrinkage of this electrode 1 when heated at 150° C. for 1 hour is −0.2% or more and 0.2% or less.

[0014] If the thermal shrinkage rate of the electrode 1 is less than −0.2% or more than 0.2%, the electrode 1 is likely to expand and contract when it is bent, which makes it difficult to prevent damage to the conductive carbon layer 4, which will be described later, and ultimately increases the rate of increase in the resistance of the conductive carbon layer 4.

[0015] To measure the thermal shrinkage of the electrode 1, the electrode 1 is heated at 150° C. for 1 hour in air at atmospheric pressure. The length of the electrode 1 before and after heating is measured to determine the thermal shrinkage of the electrode 1.

[0016] The thermal shrinkage rate of the electrode 1 is preferably −0.15% or more, more preferably −0.1% or more, and is preferably 0.15% or less, more preferably 0.1% or less.

[0017] The electrode 1 described above includes a resin film 2, a metal base layer 3, and a conductive carbon layer 4, arranged in this order toward one side in the thickness direction. Specifically, the electrode 1 includes 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. Preferably, the electrode 1 includes the resin film 2, the metal base layer 3, and the conductive carbon layer 4. Each layer will be described in detail below.

[0018] (Resin film 2) The resin film 2 forms the other surface in the thickness direction 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 in the electrode 1. The resin film 2 has, for example, flexibility. Examples of materials for the resin film 2 include polyester resins (e.g., polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate), acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyolefin resins (e.g., polyethylene, polypropylene, and polycycloolefin polymers), (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins. As the material for the resin film 2, preferably, polyester resin is used, and more preferably, polyethylene terephthalate is used, from the viewpoint of thermal stability.

[0019] There are no limitations on the thickness of the resin film 2. The thickness of the resin film 2 is, for example, 2 μm or more, or preferably 20 μm or more, and for example, 1000 μm or less, or preferably 500 μm or less.

[0020] (Metal base layer 3) The metal underlayer 3 is in contact with 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] There are no limitations on the material of the metal underlayer 3. Examples of materials for the metal underlayer 3 include metal elements classified into groups 3 to 14 in the periodic table established by IUPAC in 2019, and preferably titanium from the viewpoint of chemical stability.

[0022] There are no limitations on the thickness of the metal underlayer 3. The thickness of the metal underlayer 3 is, for example, 1 nm or more, preferably 5 nm or more, and 100 nm or less, preferably 50 nm or less.

[0023] (Conductive carbon layer 4) The conductive carbon layer 4 is conductive. The conductive carbon layer 4 forms one surface in the thickness direction of the electrode 1. The conductive carbon layer 4 is in contact with one surface in the thickness direction of the metal base layer 3. The conductive carbon layer 4 extends in the planar direction.

[0024] The conductive carbon layer 4 may be, for example, at least sp 3 Specifically, the conductive carbon layer 4 has at least sp 3 The conductive carbon layer 4 contains carbon having a bond. In other words, the conductive carbon layer 4 has at least a diamond structure. This gives the conductive carbon layer 4 high sensitivity to the measurement target.

[0025] The conductive carbon layer 4 is preferably made of sp 2 Bonds and sp 3 More specifically, the conductive carbon layer 4 has sp 2 Carbon with sp bonds 3 The conductive carbon layer 4 includes carbon having a bond. In other words, the conductive carbon layer 4 has a graphite structure and a diamond structure. This provides the conductive carbon layer 4 with excellent conductivity and high sensitivity to the object to be measured.

[0026] Furthermore, the conductive carbon layer 4 may contain, for example, oxygen in addition to carbon. Specifically, the conductive carbon layer 4 may contain, for example, oxygen on one surface in the thickness direction. The concentration ratio of oxygen to carbon (O / C) on one surface in the thickness direction of the conductive carbon layer 4 is not limited.

[0027] Furthermore, the conductive carbon layer 4 is allowed to contain trace amounts of unavoidable impurities other than oxygen.

[0028] In the conductive carbon layer 4, sp 3 Number of atoms bonded and sp 2 sp for the sum of the number of bonded atoms 3The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) is, for example, 0.10 or more, preferably 0.20 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 ) is equal to or greater than the above-mentioned lower limit, the potential window of the electrode 1 can be widened.

[0029] Also, sp 3 Number of atoms bonded and sp 2 sp for the sum of the number of bonded atoms 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.

[0030] sp 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) is a spectrum obtained by measuring one surface of the conductive carbon layer 4 in the thickness direction by X-ray photoelectron spectroscopy, 2 Bond peak intensity and sp 3 Calculations are based on peak binding intensities.

[0031] The density of the conductive carbon layer 4 is, for example, 1.8 g / cm 3 More than 2.0 g / cm 3 More preferably, 2.1 g / cm 3 More preferably, 2.2 g / cm 3 If the density of the conductive carbon layer 4 is equal to or higher than the above-mentioned lower limit, sp 3The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) is high, the potential window can be widened. In addition, the density of the conductive carbon layer 4 is, for example, 4.0 g / cm 3 The density of the conductive carbon layer 4 is determined by X-ray reflectivity.

[0032] The surface resistance of one surface of the conductive carbon layer 4 in the thickness direction is, for example, 1.0×10 4 Ω / □ or less, preferably 1.0×10 3 The surface resistance of the conductive carbon layer 4 is Ω / □ or less. There is no lower limit to the surface resistance of the conductive carbon layer 4.

[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.

[0034] The thickness of the electrode 1 is the total thickness of the resin film 2, the metal base layer 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.

[0035] (Method of manufacturing electrode 1) Next, a description will be given of a method for manufacturing the electrode 1. The method for manufacturing the electrode 1 includes first to fourth steps. In this manufacturing method, the first to fourth steps are carried out in order.

[0036] (1st step) In the first step, a resin film 2 is prepared.

[0037] (2nd process) In the second step, the resin film 2 prepared in the first step is heated.

[0038] Heating the resin film 2 is a step for adjusting the thermal shrinkage of the electrode 1 to -0.2% or more and 0.2% or less. The heating conditions are not limited. The temperature is, for example, 70°C or more, preferably 100°C or more, more preferably 130°C or more, and for example, 200°C or less, preferably 180°C or less, more preferably 160°C or less. The heating time is, for example, 5 minutes or more, preferably 15 minutes or more, more preferably 30 minutes or more, and for example, 10 hours or more, preferably 5 hours or more, more preferably 2 hours or more. The heating is carried out under normal pressure (0.1 MPa) or reduced pressure (less than 0.1 MPa). The atmosphere is air or an inert gas (including argon).

[0039] (3rd step) In the third step, a metal underlayer 3 is formed on one surface in the thickness direction of the resin film 2. There are no limitations on the method for forming the metal underlayer 3. Examples of the method for forming the metal underlayer 3 include a dry method, preferably a PVD method, and more preferably a sputtering method.

[0040] (4th step) In the fourth step, the conductive carbon layer 4 is formed on one surface in the thickness direction of the metal underlayer 3. Examples of methods for forming the conductive carbon layer 4 include dry methods. Examples of dry methods include PVD (physical vapor deposition) and CVD (chemical vapor deposition), with PVD being preferred. Examples of PVD methods include sputtering, vacuum deposition, laser deposition, and ion plating (including arc deposition). Sputtering is preferred.

[0041] Examples of sputtering methods include unbalanced magnetron sputtering (UBM sputtering), high-power pulse sputtering, electron cyclotron resonance sputtering, RF sputtering, DC sputtering, DC pulse sputtering, and ion beam sputtering. 3From the viewpoint of easily setting the ratio of the number of bonded atoms within the desired range, DC sputtering is more preferred, and DC magnetron sputtering is even more preferred.

[0042] The target used in the sputtering method may be, for example, sintered carbon. The sputtering gas may be, for example, an inert gas. The inert gas may include Ar. The pressure during sputtering is, for example, 1 Pa or less. The film formation temperature is, for example, 0°C or more and, for example, 150°C or less.

[0043] By carrying out the first to fourth steps, the electrode 1 described above is obtained.

[0044] (Use of electrode 1) Electrode 1 can be used as various electrodes, and preferably as an electrode for electrochemical measurement, specifically as a working electrode (working electrode) for performing cyclic voltammetry (CV) or anodic stripping voltammetry (ASV).

[0045] In this case, in consideration of the effects described below, the electrode 1 can be curved for use. Specifically, the electrode 1 can be used by being fixed to a curved wall surface or by being attached to a rod-shaped substrate.

[0046] (Effects of one embodiment) This electrode 1 has a thermal shrinkage rate of 0, that is, not less than −0.2% and not more than 0.2%, so that even when bent, damage to the conductive carbon layer 4 can be suppressed and the rate of increase in resistance before and after bending can be suppressed.

[0047] In addition, in the conductive carbon layer 4 of this electrode 1, sp 3 Number of atoms bonded and sp 2 sp for the sum of the number of bonded atoms 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2) is 0.10 or more, the potential window of the electrode 1 can be widened.

[0048] In this electrode 1, the conductive carbon layer 4 has a density of 1.8 g / cm 3 If the density is greater than or equal to sp 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) is high, the potential window can be widened.

[0049] (Variation) In the modified example, the same components and steps as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, the modified example can achieve the same effects as those in the first embodiment unless otherwise specified. Furthermore, the first embodiment and its modified example can be combined as appropriate.

[0050] Furthermore, it is also possible to prepare in advance in the first step a resin film 2 whose heat shrinkage rate has been adjusted to be low so that the heat shrinkage rate of the electrode 1 is -0.2% or more and 0.2% or less, without performing the second step. For example, a resin having a molecular structure with a low heat shrinkage rate may be used as a raw material, or the heat shrinkage rate of the resin film 2 itself may be reduced by heating or reducing the tension during transport at the stage of molding the resin film 2 from the raw material.

[0051] As shown in FIG. 1 , in one embodiment, an electrode 1 includes one resin film 2, one metal base layer 3, and one conductive carbon layer 4. On the other hand, as shown in FIG. 2 , an 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 one resin film 2, two metal base layers 3, and two conductive carbon layers 4. 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 toward one side in the thickness direction.

[0052] As shown in FIG. 3, the electrode 1 may not include the metal underlayer 3, but may include a resin film 2 and a conductive carbon layer 4 in this order on one side in the thickness direction. [Example]

[0053] The present invention will be described in more detail below with reference to examples and comparative examples. It should be noted that the present invention is not limited to these examples and comparative examples. The specific numerical values ​​of the blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the upper limit values ​​(numeric values ​​defined as "not more than" or "less than") or lower limit values ​​(numeric values ​​defined as "not less than" or "exceeding") of the corresponding blending ratios (content ratios), physical property values, parameters, etc. described in the above "Modes for Carrying Out the Invention." Furthermore, unless otherwise specified in the following description, "parts" and "%" are based on mass.

[0054] First, the methods for measuring the physical properties of each layer will be described.

[0055] (In the conductive carbon layer 4, sp 3 (ratio of the number of atoms bonded) In the 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 Based on the peak intensity of the bond, sp 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) was calculated.

[0056] (thickness and density) The thickness and density of the conductive carbon layer 4 were each determined based on an X-ray reflectivity method.

[0057] (Surface resistance) In accordance with JIS K 7194, the surface resistance of the electrode 1 on the conductive carbon layer 4 side was measured by the four-terminal method.

[0058] <Manufacture of electrode 1> Example 1 A resin film 2 made of polyethylene terephthalate and having a thickness of 50 μm was prepared (first step).

[0059] Subsequently, the resin film 2 was heated in a heating oven at 120° C. for 1 hour (second step).

[0060] Next, a metal underlayer 3 made of titanium was formed on one surface in the thickness direction of the resin film 2 by DC magnetron sputtering (third step). The conditions for DC magnetron sputtering were as follows:

[0061] Target material: Titanium Target power: 100W Sputtering gas: argon Sputtering chamber pressure: 0.2 Pa

[0062] The thickness of the metal underlayer 3 was 12 nm.

[0063] A conductive carbon layer 4 was formed on one surface in the thickness direction of the metal underlayer 3 by DC pulse magnetron sputtering (fourth step). The conditions for DC pulse magnetron sputtering were as follows. Target material: sintered carbon Argon gas pressure: 0.4 Pa Target power: 2.0W / cm 2 Temperature: 120℃ or less

[0064] The surface resistance of the conductive carbon layer 4 is 1.0×10 2 It was Ω / □. sp in the conductive carbon layer 4 3 Ratio (sp 3 / sp 3 +sp 2 ) is 0.35, and the density is 2.1g / cm 3 The thickness of the conductive carbon layer 4 was 40 nm.

[0065] The third and fourth steps were carried out by a roll-to-roll method.

[0066] This produced the electrode 1. The electrode 1 was produced by the roll-to-roll method described above, and therefore has an MD direction and a TD direction.

[0067] Example 2 An electrode 1 was produced in the same manner as in Example 1. However, the heating temperature in the second step was changed from 120°C to 150°C.

[0068] Example 3 An electrode 1 was produced in the same manner as in Example 2. However, the conditions for the fourth step were changed as follows. Argon gas pressure: 0.2 Pa Target power: 1.7W / cm 2

[0069] In the electrode 1 of Example 3, the surface resistance of the conductive carbon layer 4 was 140 Ω / □. 3 Ratio (sp 3 / sp 3 +sp 2 ) is 0.45, and the density is 2.3 g / cm 3 The thickness of the conductive carbon layer 4 was 40 nm.

[0070] Example 4 An electrode 1 was produced in the same manner as in Example 2. However, the conditions for the fourth step were changed as follows. Argon gas pressure: 2 Pa Target power: 1.1W / cm2

[0071] In the electrode 1 of Example 4, the surface resistance of the conductive carbon layer 4 was 160 Ω / □. 3 Ratio (sp 3 / sp 3 +sp 2 ) is 0.30, and the density is 1.8 g / cm 3The thickness of the conductive carbon layer 4 was 40 nm.

[0072] (Comparative Example 1) An electrode 1 was produced in the same manner as in Example 1, except that the second step was not carried out.

[0073] (Comparative Example 2) An electrode 1 was produced in the same manner as in Example 3, except that the second step was not carried out.

[0074] (Comparative Example 3) An electrode 1 was produced in the same manner as in Example 4, except that the second step was not carried out.

[0075] The conditions or presence or absence of the second step, the density of the conductive carbon layer 4, and the sp 3 The ratio of the number of bonded atoms (sp 3 / sp 3 +sp 2 ) are listed in Table 1.

[0076] <Evaluation> Electrode 1 was subjected to the following evaluations, and the results are shown in Table 1.

[0077] (Thermal shrinkage rate of resin film 2) Electrode 1 was cut into a square with a side length of 30 mm to prepare a sample. The sample was then heated in a heating oven at 150°C for 1 hour. The dimensions of electrode 1 before and after heating were measured using an image dimension measuring instrument (Keyence, IM-6020), and the thermal shrinkage rate was calculated using the following formula.

[0078] Heat shrinkage rate [%] = (MD length after heating - MD length before heating) / MD length before heating x 100

[0079] Generally, the thermal shrinkage in the MD direction is higher than that in the TD direction, so the thermal shrinkage in the MD direction is evaluated above. However, when the electrode 1 is manufactured by a method other than the roll-to-roll method, the thermal shrinkage in the direction with the largest absolute value can be evaluated. The above-mentioned method includes a batch method.

[0080] (Resistance increase rate of electrode 1) Sample 5 was prepared by cutting electrode 1 into a strip measuring 70 mm in longitudinal length and 20 mm in transverse length. The longitudinal direction was along the MD direction. Sample 5 was bent so that both longitudinal ends 6 of sample 5 approached each other. At this time, a central portion 7 of sample 5 in the longitudinal direction was wrapped around a metal rod 8 having a diameter of 6.5 mm. Both longitudinal ends 6 of sample 5 were fixed with clips 10 to which 150 g weights 9 were attached and held for 10 seconds. The surface resistance of electrode 1 at central portion 7 before and after bending was measured, and the resistance increase rate was calculated using the following formula.

[0081] Resistance increase rate [%] = (surface resistance of electrode 1 at center portion 7 after bending - surface resistance of electrode 1 at center portion 7 before bending) / surface resistance of electrode 1 at center portion 7 before bending × 100

[0082] Note that a test in which the resin films 2 face each other when the sample 5 is wound around the rod 8, as shown in FIG. 4, is referred to as Test A. In Test A, the rod 8, the resin film 2, the metal base layer 3, and the conductive carbon layer 4 are arranged in this order from top to bottom. In Test A, a tensile force acts on the conductive carbon layer 4 in the center.

[0083] On the other hand, a test in which the conductive carbon layers 4 face each other when the sample 5 is wound around the rod 8, as shown in Fig. 5, is designated as Test B. In Test B, the rod 8, the conductive carbon layer 4, the metal base layer 3, and the resin film 2 are arranged in this order from top to bottom. In Test B, a compressive force acts on the conductive carbon layer 4 in the center.

[0084] [Table 1]

[0085] The above invention is provided as an exemplary embodiment of the present invention, but it is merely an example and should not be interpreted as being limiting. 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 electrode is used as an electrode for electrochemical measurements. [Explanation of symbols]

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

Claims

1. An electrode including a resin film, a metal base layer, and a conductive carbon layer in this order in a thickness direction, The conductive carbon layer is sp ２ Bonds and sp ３ having a bond, The sp ３ The number of atoms bonded and the sp ２ The sp relative to the sum of the number of bonded atoms ３ The ratio of the number of bonded atoms is 0.10 or more, The conductive carbon layer has a density of 4.0 g / cm ３ Electrodes having the following densities:

2. The electrode according to claim 1 , wherein the thickness of the metal underlayer is 1 nm or more and 50 nm or less.

3. 3. The electrode according to claim 1, which is an electrode for electrochemical measurements.

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