Conductive resin film for current collector of secondary battery and method for producing same

Abstract

To provide a conductive resin film for a collector of a secondary battery, capable of preventing deterioration of a charging and discharging cycle by improving chemical resistance, preventing the collector of the secondary battery from peeling, and improving a conductivity and a weight saving in a low cost, and provide a manufacturing method of them.SOLUTION: In a conductive resin film 6 for a collector of a secondary battery, 100 pts.mass of a polyether ether ketone resin composition containing a plurality of polyether ether ketone resins having a different apparent melt viscosity each other; and 5 pts.mass or more and 30 pts.mass or less of a carbon system conductive material, and a phase crystallinity index is 80% or more. A manufacturing method of the conductive resin film has an excellent weight saving, a mechanical characteristic, chemical resistance, and heat resistance, and manufactures the conductive resin film 6 for the collector of the secondary battery by each polyether ether ketone resin with low suction water ratio, and can remove a failure that a charging and discharging cycle characteristic is deteriorated without immersing an electrolyte component in an inner part of the conductive resin film 6 for the collector even if the conductive resin film 6 for the collector is used as a collector for instance.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a conductive resin film for a current collector of a secondary battery used in a lithium ion secondary battery, an all-solid-state battery, or the like, and a method for producing the same. [Background technology]

[0002] In recent years, high-performance rechargeable secondary batteries such as nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium-ion secondary batteries, and all-solid-state batteries have been attracting attention. Among these high-performance secondary batteries, lithium-ion secondary batteries and all-solid-state batteries in particular have been attracting attention.

[0003] Although not shown, a lithium-ion secondary battery is composed of a positive electrode, a negative electrode, a separator, an electrolyte, a container, and the like. The positive electrode (positive electrode plate) consists of a current collector plate and a positive electrode mixture containing a positive electrode active material formed on the current collector plate. The positive electrode active material of this positive electrode mixture is lithium cobalt oxide, lithium manganese oxide, or the like. In contrast, the negative electrode (negative electrode plate) consists of a current collector plate and a negative electrode mixture formed on both sides of the current collector plate. The negative electrode active material of this negative electrode mixture is graphitic carbon, such as natural graphite or artificial graphite. The current collectors of these positive and negative electrodes are generally aluminum foil for the positive electrode and metal foil, such as copper foil, for the negative electrode.

[0004] Such lithium-ion secondary batteries and all-solid-state batteries have excellent characteristics, such as high energy density, high operating voltage, long life cycle, and low self-discharge, and are therefore used in a wide variety of fields, including as power sources for mobile information devices such as mobile phones, multi-function mobile phones, and tablet terminals, electronic devices such as cameras, video cameras, and portable digital music players, automobiles such as electric vehicles (EVs), hybrid vehicles (HEVs), and plug-in hybrid vehicles (PHEVs), and aircraft.

[0005] Lithium-ion secondary batteries and all-solid-state batteries used in mobile information devices, automobiles, and the like are required to have high energy densities, and one way to achieve this is to reduce the weight of the battery. Various methods have been investigated for reducing the weight of batteries, one of which is the use of conductive resin films for current collectors. That is, as described above, metal foils are used for the current collectors of the positive and negative electrodes of lithium-ion secondary batteries. However, using conductive resin films, which have a lower specific gravity than metals, instead of the metal foils can contribute to reducing the weight of the battery.

[0006] Therefore, various conductive resin films have been investigated in order to reduce the weight of secondary batteries (see Patent Documents 1, 2, and 3). For example, Patent Document 1 proposes a conductive resin film made of a cyclic olefin resin, a conductive filler, and a conjugated diene rubber, or a cyclic olefin resin, a hydrogenated product of an aromatic vinyl-conjugated diene block copolymer, a conductive filler, and a conjugated diene rubber.

[0007] Patent Document 2 proposes a current collector for a secondary battery having a conductive resin layer containing at least one resin selected from the group consisting of polyether ether ketone and a tetrafluoroethylene-hexafluoropropylene copolymer, and at least one conductive filler selected from the group consisting of ketjen black and multi-walled carbon nanotubes. Patent Document 3 also discloses a current collector for a bipolar lithium-ion secondary battery, which comprises a conductive resin layer (first conductive layer) formed by adding a conductive filler to a substrate containing an imide group-containing resin, and a conductive resin layer (second conductive layer) formed by adding a conductive filler to a substrate containing a non-imide group-containing resin, and a metal layer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-77236 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-248430 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-26192 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the conductive resin film described in Patent Document 1 has a problem with chemical resistance, and therefore, when such a conductive resin film is used as a current collector of a lithium-ion secondary battery, electrolyte components may penetrate into the conductive resin film, resulting in a deterioration in charge-discharge cycle characteristics.

[0010] In addition, in the case of the current collector for secondary batteries in Patent Document 2, ketjen black and multi-walled carbon nanotubes are used as conductive filler components, but when ketjen black is used as the conductive filler component, it is not possible to add a large amount of ketjen black to the resin, so it is not possible to achieve high conductivity for the current collector for secondary batteries. Furthermore, current collector plates containing ketjen black are brittle and may be damaged when applying positive or negative electrode active materials or when assembling them into secondary batteries.

[0011] Furthermore, conductive resin layers manufactured from a raw material mixture using multi-walled carbon nanotubes as the conductive filler instead of Ketjen black have the problem that, because the multi-walled carbon nanotubes are oriented in the plane direction, the layer has excellent conductivity in the plane direction but poor conductivity in the thickness direction. Furthermore, when tetrafluoroethylene-hexafluoropropylene copolymer is used as the resin component, the specific gravity of the resin is high, between 2.1 and 2.2, which may prevent the current collector from being lightweight. Furthermore, because tetrafluoroethylene-hexafluoropropylene copolymer is a fluororesin, special steel materials and equipment are required for melt molding, resulting in the problem of increased costs for the current collector.

[0012] Furthermore, in the case of the current collector for a bipolar lithium-ion secondary battery described in Patent Document 3, the multilayer structure is made up of two different resins, and since the two resins have different linear expansion coefficients, the difference in the expansion rate of the conductive resins caused by heat generation during repeated charging and discharging may lead to peeling of the current collector between the first and second conductive layers. Furthermore, since the resins used in the first and second conductive layers have different water absorption rates, the current collector may curl due to the difference in expansion rate caused by water absorption after production, or the current collector may peel between the first and second conductive layers.

[0013] The present invention has been made in view of the above, and aims to provide an inexpensive conductive resin film for a current collector of a secondary battery, which can improve chemical resistance to prevent a decrease in charge / discharge cycle characteristics, prevent peeling of the current collector of the secondary battery, and contribute to improving conductivity and weight reduction, and a method for producing the same. [Means for solving the problem]

[0014] As a result of extensive research, the present inventors have focused on polyether ether ketone resin, which has the highest heat resistance of all thermoplastic resin materials and also has excellent chemical resistance and mechanical properties, and carbon-based conductive materials, which are lightweight and have excellent conductivity, and have completed the present invention using these polyether ether ketone resin and carbon-based conductive materials.

[0015] That is, in order to solve the above-mentioned problems, the present invention is characterized by including 100 parts by mass of a polyether ether ketone resin composition containing at least a plurality of polyether ether ketone resins having different apparent melt viscosities from each other, and 5 to 30 parts by mass of a carbon-based conductive material, and having a relative crystallinity of 80% or more.

[0016] The thickness is between 5 μm and 500 μm, the mass change rate when immersed in N-methyl-2-pyrrolidone and electrolyte is between 0.0% and 2.0%, and the resistance when measured with a pressure of 1 MPa applied in the thickness direction is 1 mΩ cm 2 More than 1000mΩ cm 2 It is preferable that:

[0017] The multiple polyetheretherketone resins include first and second polyetheretherketone resins, and the composition mass ratios of the first and second polyetheretherketone resins are 5% by mass or more and 60% by mass or less for the first polyetheretherketone resin and 40% by mass or more and 95% by mass or less for the second polyetheretherketone resin, the first polyether ether ketone resin has an apparent melt viscosity of 50 Pa s or more and 500 Pa s or less under conditions of a temperature of 375°C and a load of 50 kgf; The second polyether ether ketone resin preferably has an apparent melt viscosity of more than 500 Pa·s and not more than 2500 Pa·s under conditions of a temperature of 375° C. and a load of 50 kgf.

[0018] The apparent melt viscosity ratio of the first and second polyether ether ketone resins under the conditions of a temperature of 375°C and a load of 50 kgf is: It is preferable that the apparent melt viscosity of the second polyether ether ketone resin / the apparent melt viscosity of the first polyether ether ketone resin be 3 / 1 or more and 15 / 1 or less.

[0019] In order to solve the above problems, the present invention provides a method for producing a conductive resin film for a current collector of a secondary battery according to claim 1 or 2, comprising the steps of: A molding material comprising 100 parts by mass of a polyether ether ketone resin composition containing at least a plurality of polyether ether ketone resins having different apparent melt viscosities from each other and 5 parts by mass or more and 30 parts by mass or less of a carbon-based conductive material is melt-kneaded; The molding material is extruded through a die into a conductive resin film for the current collector. Between the pressure roll and the cooling roll, both of which have temperatures above the glass transition temperature of the polyether ether ketone resin but below the melting point of the polyether ether ketone resin The conductive resin film for current collector is sandwiched between two layers and cooled to have a relative crystallinity of 80% or more.

[0020] Furthermore, the apparent melt viscosity of the molding material at 375°C, measured with a flow tester using a die 1.0 mm in diameter and 10 mm in length under conditions of a temperature of 375°C and a load of 50 kgf, should be between 50 Pa·s and 10,000 Pa·s. The cooled conductive resin film for a current collector is then heat-compressed and molded, and the heating temperature of the conductive resin film for a current collector is set to a temperature equal to or higher than the melting point of the polyether ether ketone resin but lower than the thermal decomposition temperature. The pressure applied to the conductive resin film for a current collector is set to 0.5 kgf / cm with respect to the projected area of ​​the conductive resin film for a current collector. 2 More than 100kgf / cm 2 It would be better to use the following.

[0021] The polyetheretherketone (PEEK) resin composition and the carbon-based conductive material in the claims can be melt-kneaded at a temperature equal to or higher than the melting point of the polyetheretherketone resin and lower than the thermal decomposition temperature of the polyetheretherketone resin. A polyarylene ether ketone resin, such as polyetherketone (PEK) resin, polyetherketoneketone (PEKK) resin, polyetheretherketoneketone (PEEKK) resin, or polyetherketoneetherketoneketone (PEKEKK) resin, can be added to the polyetheretherketone resin as needed, within the range that does not impair the properties of the present invention.

[0022] The carbon-based conductive material includes at least carbon nanotubes. The conductive resin film for a current collector may be any of a uniaxially stretched type, a biaxially stretched type, and a non-stretched type. The conductive resin film for a current collector includes a thin conductive resin film for a current collector as well as a thick conductive resin sheet for a current collector. The molding material can be prepared by stirring and mixing a plurality of polyether ether ketone resin compositions having different apparent melt viscosities with a carbon-based conductive material, followed by melt-kneading.

[0023] The secondary battery according to the present invention includes at least a nickel-cadmium storage battery, a nickel-metal hydride storage battery, a nickel-zinc storage battery, a lithium ion secondary battery, a bipolar lithium ion secondary battery, an all-solid-state battery, etc. Furthermore, the conductive resin film for the current collector preferably has a specific gravity of 1.23 to 1.60, a maximum tensile strength of 60 MPa to 500 MPa, a tensile elongation at break of 10% to 500%, and a tensile modulus of elasticity of 2000 MPa to 10000 MPa.

[0024] According to the present invention, a conductive resin film for a current collector is manufactured using a polyether ether ketone resin composition containing multiple polyether ether ketone resins that are lightweight, excellent in mechanical strength, chemical resistance, etc., and that have low water absorption and different apparent melt viscosities. Therefore, even when the conductive resin film for a current collector is used as a current collector, there is little penetration of electrolyte components into the conductive resin film for a current collector. Furthermore, since there is no need to use two different resins, the risk of peeling of the current collector can be eliminated. In addition, there is little risk of curling due to differences in expansion coefficients caused by water absorption after production, or peeling of the current collector between the first and second conductive layers. [Effects of the Invention]

[0025] According to the present invention, it is possible to improve chemical resistance, prevent deterioration of charge / discharge cycle characteristics, prevent peeling of the current collector of a secondary battery, and further contribute to improving conductivity and weight reduction.

[0026] According to the invention of claim 2, the thickness of the conductive resin film for current collector is 5 μm or more and 500 μm or less, thereby preventing a decrease in the tensile strength of the conductive resin film for current collector and enabling a reduction in the weight of the current collector of a secondary battery. Furthermore, the conductive resin film for current collector has a mass change rate of 2.0% or less when immersed in N-methyl-2-pyrrolidone and an electrolyte solution, thereby achieving excellent chemical resistance. Furthermore, the conductive resin film for current collector has a resistance value of 1 mΩ·cm when measured by applying a pressure of 1 MPa in the thickness direction. 2 More than 1000mΩ cm 2Since the electroconductive resin film for a current collector has a low electrical conductivity of 0.1 to 1.0 V, even when the electroconductive resin film for a current collector is used as a current collector for a secondary battery, a decrease in energy density can be prevented.

[0027] According to the invention of claim 3, the composition mass ratio of the first and second polyether ether ketone resins is 5% to 60% by mass for the first polyether ether ketone resin and 40% to 95% by mass for the second polyether ether ketone resin, making it possible to obtain a conductive resin film for a current collector that has excellent conductivity and mechanical strength and achieves excellent film formability.In addition, the apparent melt viscosity of the first polyether ether ketone resin at a temperature of 375°C and a load of 50 kgf is 50 Pa s to 500 Pa s, making it possible to improve the conductivity of the conductive resin film for a current collector and prevent a decrease in mechanical strength.

[0028] According to the invention of claim 4, the apparent melt viscosity of the second polyether ether ketone resin / the apparent melt viscosity of the first polyether ether ketone resin is equal to or greater than 3 / 1 and equal to or less than 15 / 1, so that excessive similarity in the properties of the first and second polyether ether ketone resins can be suppressed, and electrical conductivity can be suitably improved.Furthermore, the first and second polyether ether ketone resins can be uniformly dispersed, eliminating the risk of fisheyes or holes occurring.

[0029] According to the invention of claim 5, the conductive resin film for current collector is produced by melt extrusion molding, which is expected to improve the thickness accuracy, productivity, and handling properties of the conductive resin film for current collector, and to simplify the manufacturing equipment. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 2 is an explanatory view schematically showing a melt kneader for the first and second polyether ether ketone resins in the embodiment of the method for producing a conductive resin film for a current collector of a secondary battery according to the present invention. [Figure 2]FIG. 1 is an explanatory diagram schematically illustrating a melt kneader for a polyether ether ketone resin composition and a carbon-based conductive material in an embodiment of a method for producing a conductive resin film for a current collector of a secondary battery according to the present invention. [Figure 3] 1 is an overall explanatory view schematically illustrating a manufacturing apparatus in an embodiment of a conductive resin film for a current collector of a secondary battery according to the present invention and a manufacturing method thereof. [Figure 4] 1A and 1B are cross-sectional explanatory views schematically illustrating measurement states of the conductivity of conductive resin films for current collectors in examples and comparative examples of the method for producing a conductive resin film for current collectors of secondary batteries according to the present invention. [Figure 5] FIG. 2 is a partial plan view illustrating a schematic diagram of the measurement state of the conductivity of a conductive resin film for a current collector in an example and a comparative example of the method for producing a conductive resin film for a current collector of a secondary battery according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] A preferred embodiment of the present invention will now be described with reference to the drawings. In this embodiment, a conductive resin film 6 for a current collector of a secondary battery is a conductive resin film having a relative crystallinity of 80% or more, which is formed from a molding material 1 containing a polyether ether ketone resin composition 2 containing multiple polyether ether ketone resins having at least different apparent melt viscosities, and a carbon-based conductive material 5 having excellent conductivity, as shown in FIGS. 1 to 3 , and contributes to the achievement of Goal 9 of the SDGs (the United Nations' international goals for sustainable development, consisting of 17 global goals and 169 targets (achievement criteria)) adopted at the United Nations Summit.

[0032] Molding material 1 is prepared to contain 100 parts by mass of a polyether ether ketone resin composition containing multiple polyether ether ketone (PEEK) resins with different apparent melt viscosities, and 5 to 30 parts by mass of a carbon-based conductive material. The mass ratio of the carbon-based conductive material 5 to 100 parts by mass of the polyether ether ketone resin composition is preferably 5 to 30 parts by mass, more preferably 8 to 25 parts by mass, and even more preferably 10 to 20 parts by mass.

[0033] When the amount of the carbon-based conductive material 5 is less than 5 parts by mass, the resistance value measured by applying a pressure of 1 MPa in the thickness direction of the conductive resin film 6 for current collector is 1000 mΩ cm 2 If the carbon-based conductive material 5 does not exceed 30 parts by mass, sufficient conductivity cannot be imparted to the conductive resin film 6 for current collector, making it difficult to use the film as a current collector for a secondary battery. On the other hand, if the carbon-based conductive material 5 exceeds 30 parts by mass, the melt viscosity of the molding material 1 increases, leading to a decrease in melt flowability, and the processability of the conductive resin film 6 for current collector decreases due to a decrease in melt elongation, resulting in the formation of holes in the conductive resin film 6 for current collector. In addition, it becomes difficult to blend the carbon-based conductive material 5 into multiple polyether ether ketone resins.

[0034] Furthermore, if the carbon-based conductive material 5 exceeds 30 parts by mass, the carbon-based conductive material 5 separates from the conductive resin film 6 for current collector, causing the generation of die fill, which leads to a deterioration in the quality of the conductive resin film 6 for current collector. Explaining this point in more detail, when the conductive resin film 6 for current collector is molded into a film, a large amount of deposits called die fill may adhere and accumulate at the exit (also referred to as the die lip) of the molding die 33 shown in FIG. 3. The accumulation of this die fill may cause die lines to appear in the conductive resin film 6 for current collector, or the die fill may leave the die exit and be mixed into the conductive resin film 6 for current collector, resulting in a deterioration in the quality of the conductive resin film 6 for current collector.

[0035] Furthermore, if the amount of the carbon-based conductive material 5 exceeds 30 parts by mass, in addition to the above, the toughness of the conductive resin film 6 for a current collector is lost, and the conductive resin film 6 for a current collector may crack during molding of the conductive resin film 6 for a current collector, during the coating process of the positive electrode active material or the negative electrode active material, or during assembly of the secondary battery.

[0036] The polyetheretherketone resin composition 2 of the molding material 1 contains a plurality of polyetheretherketone resins, namely, a low-viscosity first polyetheretherketone resin 3 and a high-viscosity second polyetheretherketone resin 4, and the composition mass ratios of these first and second polyetheretherketone resins 3 and 4 are adjusted to 5% by mass or more and 60% by mass or less for the first polyetheretherketone resin and 40% by mass or more and 95% by mass or less for the second polyetheretherketone resin, so that the apparent melt viscosities of the first and second polyetheretherketone resins 3 and 4 are different from each other.

[0037] The polyether ether ketone resin composition 2 has an apparent melt viscosity, under conditions of a temperature of 375°C and a load of 50 kgf, of 50 Pa·s or more and 2500 Pa·s or less, preferably 75 Pa·s or more and 2000 Pa·s or less, more preferably 100 Pa·s or more and 1500 Pa·s or less, and even more preferably 100 Pa·s or more and 1200 Pa·s or less. This is because if the apparent melt viscosity is less than 50 Pa·s, the polyether ether ketone resin is in the oligomer region, which not only fails to improve the conductivity of the conductive resin film for current collector 6 but also may reduce the mechanical strength. On the other hand, if the apparent melt viscosity exceeds 2500 Pa·s, it is not possible to uniformly disperse the carbon-based conductive material 5 in the polyether ether ketone resin composition 2.

[0038] The first and second polyether ether ketone resins 3 and 4 are crystalline thermoplastic resins consisting of arylene groups, ether groups, and carbonyl groups. Examples of such resins include those described in Japanese Patent No. 5702283 and Japanese Patent No. 5847522, and in the literature [Asahi Research Center Co., Ltd.: PEEK, a super engineering plastic growing in cutting-edge applications (Part 1)]. These resins are characterized by excellent mechanical strength, light weight, low dielectric properties, hydrolysis resistance, heat resistance, chemical resistance, and the like.

[0039] Specific examples of the first and second polyether ether ketone resins 3 and 4 include polyether ether ketone resins having a chemical structural formula represented by chemical formula (1), which have a melting point of typically 320 to 360°C, preferably 335 to 345°C, and are typically used in a form suitable for molding, such as powder, granules, or pellets.

[0040] [ka]

[0041] In terms of improving mechanical properties, n in the structural formula of the first and second polyether ether ketone resins 3·4 is preferably 10 or more, and more preferably 20 or more. The first and second polyether ether ketone resins 3·4 may be homopolymers consisting only of repeating units of chemical formula (1), or may contain repeating units other than those of chemical formula (1). Furthermore, the proportion of the chemical structure of chemical formula (1) in the first and second polyether ether ketone resins 3·4 is preferably 50 mol % or more, preferably 70 mol % or more, and more preferably 80 mol % or more, relative to 100 mol % of the polyether ether ketone resin. The first and second polyether ether ketone resins 3·4 may also be block copolymers, random copolymers, or modified products with other copolymerizable monomers, as long as the effects of the present invention are not impaired.

[0042] Examples of the first and second polyether ether ketone resins 3 and 4 include Victrex Powder series and Victrex Granules series manufactured by Victrex, VestaKeep series manufactured by Diesel-Evonik, and KetaSpire PEEK series manufactured by Solvay Specialty Polymers.

[0043] The methods for producing the first and second polyether ether ketone resins are not particularly limited, but a typical production method includes polycondensing an aromatic diol component and an aromatic dihalide component (wherein one of the components contains at least a component having a carbonyl group) in the presence of an alkali metal salt and a solvent at a temperature ranging from 150°C to 400°C. Examples of aromatic diol components include hydroquinone, and examples of aromatic dihalide components include 4,4'-difluorobenzophenone. Examples of alkali metal salts include inorganic potassium carbonate, and examples of solvents include diphenyl sulfone. After the polycondensation reaction is complete, the resin may be pulverized, washed with acetone, methanol, ethanol, water, or the like, and then dried.

[0044] The first and second polyether ether ketone resins 3 and 4 may be used by appropriately adjusting the crystallization temperature by modifying the terminal groups (usually halogen atoms) with alkaline sulfonic acid groups (sodium sulfonate groups, potassium sulfonate groups, lithium sulfonate groups, etc.), but it is preferable to use them without modifying the terminal groups.

[0045] The composition mass ratio of the first and second polyetheretherketone resins 3 and 4 is 5% by mass or more and 60% by mass or less for the first polyetheretherketone resin and 40% by mass or more and 95% by mass or less for the second polyetheretherketone resin, but preferably the composition mass ratio of the first polyetheretherketone resin 3 is 10% by mass or more and 50% by mass or less, more preferably the composition mass ratio is 15% by mass or more and 40% by mass or less, and even more preferably the composition mass ratio is 20% by mass or more and 40% by mass or less.

[0046] This is because, when the composition mass ratio of the first and second polyether ether ketone resins 3 and 4 is within the above range, a conductive resin film 6 for a current collector having excellent conductivity and mechanical strength can be obtained, and also because a molding material 1 having excellent film formability can be obtained.

[0047] The first polyether ether ketone resin 3 has an apparent melt viscosity of 50 Pa·s to 500 Pa·s, preferably 75 Pa·s to 400 Pa·s, more preferably 90 Pa·s to 300 Pa·s, and even more preferably 100 Pa·s to 200 Pa·s, under conditions of a temperature of 375°C and a load of 50 kgf. This is because if the apparent melt viscosity is less than 50 Pa·s, the polyether ether ketone resin is in the oligomer region, which not only fails to improve the conductivity of the conductive resin film for current collector 6 but also may reduce the mechanical strength. On the other hand, if the apparent melt viscosity exceeds 500 Pa·s, improvement of conductivity will be hindered.

[0048] The apparent melt viscosity of the first polyether ether ketone resin 3 can be measured with a flow tester using a die having a diameter of 1.0 mm and a length of 10 mm under conditions of a temperature of 375° C. and a load of 50 kgf.

[0049] The second polyether ether ketone resin 4 has an apparent melt viscosity of more than 500 Pa·s and not more than 2500 Pa·s, preferably 700 Pa·s or more and not more than 2000 Pa·s, more preferably 900 Pa·s or more and not more than 1500 Pa·s, and even more preferably 900 Pa·s or more and not more than 1200 Pa·s, under conditions of a temperature of 375°C and a load of 50 kgf. The apparent melt viscosity of the second polyether ether ketone resin 4 can also be measured with a flow tester using a die with a diameter of 1.0 mm and a length of 10 mm under conditions of a temperature of 375°C and a load of 50 kgf.

[0050] The apparent melt viscosity ratio of the first and second polyetheretherketone resins 3 and 4 at a temperature of 375°C and a load of 50 kgf (apparent melt viscosity of second polyetheretherketone resin 4 / apparent melt viscosity of first polyetheretherketone resin 3) is preferably in the range of 3 / 1 or more and 15 / 1 or less, preferably 4 / 1 or more and 13 / 1 or less, more preferably 4.5 / 1 or more and 11 / 1 or less, and even more preferably 5 / 1 or more and 10 / 1 or less, because this can significantly improve the properties of the polyetheretherketone resins.

[0051] This is because, if the apparent melt viscosity of the second polyetheretherketone resin 4 is less than three times the apparent melt viscosity of the first polyetheretherketone resin 3, the properties of the second polyetheretherketone resin 4 and the first polyetheretherketone resin 3 tend to be too similar, making it difficult to improve the electrical conductivity. On the other hand, if the apparent melt viscosity of the second polyetheretherketone resin 4 is more than 15 times the apparent melt viscosity of the first polyetheretherketone resin 3, the difference in apparent melt viscosity is so large that it becomes difficult to uniformly disperse the first and second polyetheretherketone resins 3 and 4, and fisheyes and holes may occur.

[0052] Examples of the carbon-based conductive material 5 of the molding material 1 include carbon black such as furnace black (oil furnace black and gas furnace black), channel black, acetylene black, and thermal black; carbon fibers such as carbon nanotubes, carbon nanofibers, fullerenes, amorphous carbon, bread-based carbon fibers, and pitch-based carbon fibers; and graphite such as flake graphite, lump graphite, earthy graphite, expanded graphite obtained by chemically treating flake graphite with concentrated sulfuric acid or the like and then heating it; expanded graphite obtained by heat-treating expanded graphite at high temperatures; and artificial graphite.

[0053] Among these carbon-based conductive materials 5, carbon nanotubes are optimal because they can provide high conductivity with a small amount and can be used to form the conductive resin film 6 for the current collector without losing the mechanical strength of the conductive resin film 6 for the current collector. These carbon nanotubes have a cylindrical hollow fiber structure, and are therefore expected to contribute to weight reduction. Carbon nanotubes include single-walled carbon nanotubes, which have a structure in which one surface of graphite is wrapped around them, and multi-walled carbon nanotubes, which have two or more layers wrapped around them, but are not particularly limited.

[0054] Carbon nanotubes other than these single-walled carbon nanotubes and multi-walled carbon nanotubes include nanografibers, bamboo-shaped nanotubes, and cup-stacked nanotubes, which are described in "Introduction to Materials Chemistry of Carbon Nanotubes" (Corona Publishing, edited by Yahachi Saito, pp. 7-9). Also included are carbon nanotube analogs such as nanohorns, nanocones, microcoils, and nanocoils, which are described in "Introduction to Materials Chemistry of Carbon Nanotubes" (Corona Publishing, edited by Yahachi Saito, pp. 9-11). Among these carbon nanotubes and their analogs, multi-walled carbon nanotubes are the most suitable from the viewpoint of cost reduction.

[0055] The fiber diameter (outer diameter) of the carbon nanotubes is not particularly limited, but is preferably 0.5 nm or more and 200 nm or less. These carbon nanotubes can be produced by known production methods. For example, they can be produced by (1) the arc discharge method, (2) the laser evaporation method, or (3) chemical vapor deposition methods (or pyrolysis methods) such as the substrate growth method, supported catalyst method, fluidized catalyst method, and HiPco method, as described in "Introduction to Materials Chemistry of Carbon Nanotubes" (Corona Publishing, edited by Yahachi Saito, pp. 11-12). They can also be produced by the eDPIS method, the Supergloss method, or the like.

[0056] Examples of carbon nanotube products include Supergrowth CNT (manufactured by the New Energy and Industrial Technology Development Organization), eDIPS-CNT (manufactured by the New Energy and Industrial Technology Development Organization), SWNT series (manufactured by Meijo Nanocarbon Co., Ltd.: product name), VGCF series (manufactured by Showa Denko K.K.: product name), FloTube series (manufactured by CNano Technology: product name), AMC (manufactured by Ube Industries, Ltd.: product name), Nanocyl NC7000 series (manufactured by Nanocyl: product name), Baytubes (manufactured by BAYER: product name), GRAPHISTRENGTH (manufactured by Arkema: product name), MWNT7 (manufactured by Hodogaya Chemical Co., Ltd.: product name), K-Nanos series (manufactured by Kumho), and Hyperion CNT (manufactured by Hypeprion Catalysis International: product name).

[0057] Other metallic or carbonaceous conductive materials may be added to the carbon nanotubes as long as the properties of the present invention are not impaired. Metallic conductive materials include, for example, gold, silver, copper, nickel, iron, aluminum, chromium, niobium, titanium, tin, vanadium, and alloys containing two or more of these, metal oxides, metal carbides, and metal nitrides.

[0058] The carbonaceous conductive material 5 may be in any form, such as powder, granules, lumps, fibers, etc. One type may be used alone, or two or more types may be used in combination. Furthermore, the carbon-based conductive material 5 may contain, within a range that does not impair the properties of the conductive resin film 6 for current collector, a compound selected from the group consisting of a silane coupling agent (vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-aminopropylethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-ureidopropyltrialkoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-trimethoxysilylpropylsuccinic anhydride, imidazole silane, etc.), a titanate-based coupling agent (isopropyl triisostearoyl titanate, isopropyl(diisopropyl)succinic anhydride, imidazole silane, etc.), a silane ... octyl pyrophosphate) titanate, isopropyl tris(N-aminoethyl-aminoethyl) titanate, tetraoctyl bis(di-tridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl) bis(di-tridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate, isopropyl The coating may be treated with various coupling agents such as dimethacryl isostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctylphosphate) titanate, isopropyl tricumylphenyl titanate, tetraisopropyl(dioctylphosphite) titanate, and aluminate coupling agents such as acetoalkoxyaluminum diisopropylate.

[0059] The molding material 1 may include, in addition to the polyether ether ketone resin composition 2 and the carbon-based conductive material 5, polyolefin resins such as polyethylene (PE) resin, polypropylene (PP) resin, polymethylpentene (PMP) resin, and polystyrene (PS) resin, acid-modified olefin resins such as maleic anhydride-modified polyethylene resin and maleic anhydride-modified polypropylene resin, polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, and polyethylene naphthalate (PEN) resin, as long as the characteristics of the present invention are not impaired. Polyester resins such as polyester, polyimide (PI) resin, polyamideimide (PAI) resin, polyetherimide (PEI) resin, and other polyimide resins, polyamide 4T (PA4T) resin, polyamide 6T (PA6T) resin, modified polyamide 6T (modified PA6T) resin, polyamide 9T (PA9T) resin, polyamide 10T (PA10T) resin, polyamide 11T (PA11T) resin, polyamide 6 (PA6) resin, polyamide 66 (PA66) resin, polyamide 46 (PA46) resin, and other polyamide resins, polysulfone (PSU) ) resin, polysulfone resins such as polyethersulfone (PES) resin and polyphenylene sulfone (PPSU) resin, polyarylene sulfide resins such as polyphenylene sulfide (PPS) resin, polyphenylene sulfide ketone resin, polyphenylene sulfide sulfone resin and polyphenylene sulfide ketone sulfone resin, polytetrafluoroethylene (PTFE) resin, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin, tetrafluoroethylene-hexafluoropropylene Fluororesins such as vinylidene fluoride copolymer (FEP) resin, tetrafluoroethylene-ethylene copolymer (ETFE) resin, polychlorotrifluoroethylene (PCTFE) resin, polyvinylidene fluoride (PVdF) resin, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resin, and acid-modified fluororesins, as well as thermoplastic resins such as polycarbonate (PC) resin, polyarylate (PAR) resin, polyacetal (POM) resin, liquid crystal polymer (LCP), and aliphatic polyketone resin can be selectively added.

[0060] Furthermore, in addition to the polyether ether ketone resin composition 2, the carbon-based conductive material 5, and the thermoplastic resin, predetermined additives can be selectively added to the molding material 1, provided that the properties of the present invention are not impaired. Specifically, nucleating agents, impact modifiers, antioxidants, light stabilizers, ultraviolet absorbers, plasticizers, lubricants, flame retardants, heat resistance improvers, inorganic fillers, organic fillers, glass fibers, carbon fibers, etc. can be selectively added.

[0061] The apparent melt viscosity of molding material 1 is measured using a flow tester at a temperature of 375°C under conditions of a temperature of 375°C and a load of 50 kgf using a die with a diameter of 1.0 mm and a length of 10 mm, and is preferably in the range of 50 Pa·s or more and 10,000 Pa·s or less, preferably 100 Pa·s or more and 5,000 Pa·s or less, and more preferably 500 Pa·s or more and 2,500 Pa·s or less.

[0062] This is because, if the apparent melt viscosity is in the range of 50 Pa·s to 10,000 Pa·s, the conductive resin film 6 for current collectors has excellent formability and can be expected to have sufficient mechanical strength. On the other hand, if the apparent melt viscosity is less than 50 Pa·s, the apparent melt viscosity is low, which leads to a decrease in melt tension and makes it difficult to form the conductive resin film 6 for current collectors. On the other hand, if the apparent melt viscosity exceeds 10,000 Pa·s, the melt viscosity is high and the melt elongation is low, which may cause holes to form in the conductive resin film 6 for current collectors and cause breakage, resulting in difficulties in forming the conductive resin film 6 for current collectors.

[0063] In the above, when producing the conductive resin film 6 for a current collector, first, a polyether ether ketone resin composition 2 containing a plurality of polyether ether ketone resins having different apparent melt viscosities is prepared, and this polyether ether ketone resin composition 2 and a carbon-based conductive material 5 are melt-kneaded for a predetermined time to prepare a molding material 1. Thereafter, by feeding the molding material 1 into a melt extrusion molding machine 30 for molding a resin film, a conductive resin film 6 for a current collector having a thickness of 500 μm or less, for example, from 10 μm to 500 μm, can be produced by melt extrusion molding.

[0064] Methods for preparing the polyether ether ketone resin composition 2 include: (1) a method in which first and second polyether ether ketone resins 3 and 4 having different apparent melt viscosities are charged into a melt kneader 10 and melt-kneaded to prepare the polyether ether ketone resin composition 2; and (2) a method in which first and second polyether ether ketone resins 3 and 4 having different apparent melt viscosities are stirred and mixed in a stirring mixer at room temperature (a temperature of about 0°C or higher and about 50°C or lower) to prepare the polyether ether ketone resin composition 2.

[0065] First, the preparation method (1) will be described in detail. In this method, a predetermined melt kneader 10 shown in Fig. 1 is prepared, and the first and second polyether ether ketone resins 3 and 4 are simultaneously fed into this melt kneader 10 through an inlet 15, or the first polyether ether ketone resin 3 is fed through the inlet 15 and the second polyether ether ketone resin 4 is separately fed through a side feeder 16, and melt-kneaded to prepare a polyether ether ketone resin composition 2. Alternatively, the second polyether ether ketone resin 4 may be fed into the inlet 15, and the first polyether ether ketone resin 3 may be separately fed through the side feeder 16, and melt-kneaded.

[0066] Examples of the melt kneader 10 include a Banbury mixer, a mixing roll, a pressure kneader, a single-screw extruder, or a multi-screw extruder consisting of a twin-screw extruder, a triple-screw extruder, a four-screw extruder, or an eight-screw extruder. Among these, a vent-type multi-screw extruder is preferred, as it is expected to achieve good kneading and dispersion of the first and second polyether ether ketone resins 3 and 4 and is capable of degassing the moisture and volatile gases generated therefrom.

[0067] The temperature during melt-kneading in the melt-kneader 10 is not particularly limited as long as it allows melt-kneading and dispersion and does not decompose the first and second polyetheretherketone resins 3·4, but is preferably in the range of from the melting points to the thermal decomposition temperatures of the first and second polyetheretherketone resins 3·4. Specifically, the temperature is in the range of from 360°C to 450°C, preferably from 360°C to 420°C, and more preferably from 370°C to 400°C. This is because, if the temperature during melt-kneading in the melt-kneader 10 is below the melting points of the first and second polyetheretherketone resins 3·4, the first and second polyetheretherketone resins 3·4 will not melt and will not be able to be kneaded and dispersed together. Furthermore, if the temperature of the melt kneader 10 exceeds the thermal decomposition temperature of the first and second polyether ether ketone resins 3 and 4, the first and second polyether ether ketone resins 3 and 4 will be violently decomposed, which is undesirable.

[0068] As shown in FIG. 1 , melt mixer 10, which is a multi-screw extruder, is equipped with: cylinder 12 mounted on base 11; screw 13, which is built into cylinder 12 and axially supported by a motor, which rotates to melt-mix first and second polyether ether ketone resins 3 and 4 together and extrudes strands (rod-shaped) or the like from a die 14 at the tip of the screw; inlet 15 for first polyether ether ketone resin 3, which is a hopper connected to the upstream part of cylinder 12; side feeder 16 for feeding second polyether ether ketone resin 4, which is connected to the downstream part of cylinder 12; and a rotatable cutter 17 that cuts the strands extruded from die 14 of cylinder 12 and cooled with air or water to produce polyether ether ketone resin composition 2.

[0069] When the polyetheretherketone resin composition 2 is kneaded and dispersed using such a melt kneader 10, the first polyetheretherketone resin 3 is introduced into the inlet 15 of the melt kneader 10, and then the second polyetheretherketone resin 4 is introduced laterally into the side feeder 16 of the cylinder 12, which has a screw structure. This allows the second polyetheretherketone resin 4 to be injected into the molten first polyetheretherketone resin 3, thereby appropriately kneading and dispersing the first and second polyetheretherketone resins 3 and 4, which have different apparent melt viscosities. This shortens the melt kneading time, which is expected to prevent thermal decomposition and crosslinking of the first and second polyetheretherketone resins 3 and 4. Alternatively, the second polyetheretherketone resin 4 may be introduced into the inlet 15 of the melt kneader 10, and then the first polyetheretherketone resin 3 may be introduced laterally into the side feeder 16 of the cylinder 12.

[0070] The kneaded and dispersed first and second polyether ether ketone resins 3 and 4 are extruded from a die 14 in the form of strands to form a polyether ether ketone resin composition 2, but after being extruded from the die 14 as a polyether ether ketone resin film, the polyether ether ketone resin composition 2 may be prepared by processing it into powder, granules, flakes, or pellets.

[0071] Next, the preparation method (2) will be described in detail. In this method, first and second polyether ether ketone resins 3·4 having different apparent melt viscosities can be prepared by stirring and mixing them at room temperature. When stirring and mixing the first and second polyether ether ketone resins 3·4 together at room temperature, a stirring and mixing machine such as a tumbler mixer, Henschel mixer, V-type mixer, Nauta mixer, ribbon blender, or universal stirring mixer is used. In this case, the first and second polyether ether ketone resins 3·4 are preferably in a powder form, which contributes to uniform dispersion. Methods for pulverizing them into a powder form include, for example, shear pulverization, impact pulverization, collision pulverization, freeze pulverization, and solution pulverization.

[0072] Next, a method for preparing the molding material 1 using the polyether ether ketone resin composition 2 will be described. Examples of methods for preparing this molding material 1 include: (1) a method in which a carbon-based conductive material 5 is introduced into a melt kneader 20 for the molding material 1 and melt-kneaded with the molten polyether ether ketone resin composition 2 to prepare the molding material 1; and (2) a method in which the polyether ether ketone resin composition 2 and the carbon-based conductive material 5 are stirred and mixed at room temperature (a temperature of about 0°C or higher and 50°C or lower) using a stirring mixer, and then melt-extruded and kneaded in the melt kneader 20 to prepare the molding material 1.

[0073] First, the preparation method (1) will be described in detail. In this method, a predetermined melt kneader 20 shown in FIG. 2 is prepared, a polyether ether ketone resin composition 2 is charged into this melt kneader 20 and melted, and then a carbon-based conductive material 5 is newly charged into the melt kneader 20 by a side feeder method or the like and melt-kneaded with the already melted polyether ether ketone resin composition 2 to prepare a molding material 1.

[0074] Examples of the melt kneader 20 include a Banbury mixer, a mixing roll, a pressure kneader, and a multi-screw extruder consisting of a single-screw extruder, a twin-screw extruder, a triple-screw extruder, a four-screw extruder, or an eight-screw extruder. Among these, it is preferable to use a vent-type multi-screw extruder, which is expected to achieve good kneading and dispersion of the polyether ether ketone resin composition 2 and the carbon-based conductive material 5 and can degas the moisture and volatile gases generated therefrom.

[0075] As shown in FIG. 2 , melt kneader 20, which is a multi-screw extruder, is equipped with: cylinder 22 installed on base 21; screw 23, which is built into and journaled in cylinder 22 and rotates by a motor to melt-knead polyether ether ketone resin composition 2 and carbon-based conductive material 5, and extrudes strands or the like from a die 24 at the tip of the screw; inlet 25 for polyether ether ketone resin composition 2, which is a hopper connected to the upstream part of cylinder 22; side feeder 26 for carbon-based conductive material 5, which is connected to the downstream part of cylinder 22; and rotatable cutter 27, which cuts the strands or the like extruded from die 24 of cylinder 22 and cooled with air or water, to obtain molding material 1.

[0076] When such a melt kneader 20 is used to knead and disperse the polyether ether ketone resin composition 2 and the carbon-based conductive material 5, the polyether ether ketone resin composition 2 is charged into the inlet 25 of the melt kneader 20, and then the fine powder of the carbon-based conductive material 5 is charged from the side using the side feeder 26 with a screw structure of the cylinder 22, thereby injecting the carbon-based conductive material 5 into the molten polyether ether ketone resin composition 2, and the polyether ether ketone resin composition 2 and the carbon-based conductive material 5 can be uniformly and appropriately kneaded and dispersed. In this case, the kneading time can be shortened, which is expected to prevent decomposition of the polyether ether ketone resin composition 2.

[0077] The melting temperature when melt-kneading the polyether ether ketone resin composition 2 and the carbon-based conductive material 5 is not particularly limited as long as it is a temperature that allows melt-kneading dispersion and does not decompose the polyether ether ketone resin composition 2, but is in the range of the melting point of the polyether ether ketone resin to less than the thermal decomposition temperature of the polyether ether ketone resin. Specifically, the range is 360°C to 450°C, preferably 360°C to 420°C, and more preferably 370°C to 400°C.

[0078] This is because if the temperature during melt-kneading in the melt-kneader 20 is lower than the melting point of the polyether ether ketone resin, the polyether ether ketone resin composition 2 does not melt, and therefore it is not possible to uniformly disperse the polyether ether ketone resin composition 2 and the carbon-based conductive material 5. Conversely, if the temperature of the melt-kneader 20 exceeds the thermal decomposition temperature of the polyether ether ketone resin composition 2, the polyether ether ketone resin composition 2 will be violently decomposed, and this is therefore preferable.

[0079] The melt-kneaded polyether ether ketone resin composition 2 and carbon-based conductive material 5 are extruded from a die 24 as strands to prepare the strand molding material 1, but after being extruded from the die 24 as a resin film, the resin may be prepared into powder, granules, flakes, or pellets as the molding material 1. When preparing the molding material 1, a predetermined amount or more of either the polyether ether ketone resin composition 2 or the carbon-based conductive material 5 may be dispersed to form a masterbatch.

[0080] Next, the preparation method (2) will be described in detail. When this method is used to stir and mix the polyether ether ketone resin composition 2 and the carbon-based conductive material 5 at room temperature, a stirring mixer such as a tumbler mixer, a Henschel mixer, a V-type mixer, a Nauta mixer, a ribbon blender, or a universal stirring mixer is used. In this case, the polyether ether ketone resin composition 2 is preferably in the form of powder so that it can be more uniformly dispersed with the carbon-based conductive material 5. Examples of methods for pulverizing into this powder form include shear pulverization, impact pulverization, collision pulverization, freeze pulverization, and solution pulverization.

[0081] The polyether ether ketone resin composition 2 and the carbon-based conductive material 5 are stirred and mixed, and then melt-kneaded and dispersed in a melt kneader 20 such as a Banbury mixer, mixing roll, pressure kneader, single-screw extruder, or a multi-screw extruder consisting of a twin-screw extruder, a triple-screw extruder, a four-screw extruder, or an eight-screw extruder, to prepare the molding material 1. The melt kneader 20 is preferably a vent-type multi-screw extruder, which is expected to achieve good kneading and dispersion of the polyether ether ketone resin composition 2 and the carbon-based conductive material 5 and is capable of degassing the moisture and volatile gases generated therefrom. When preparing the molding material 1, a predetermined amount or more of either the polyether ether ketone resin composition 2 or the carbon-based conductive material 5 can be dispersed to form a masterbatch.

[0082] The moisture content (water content) of the molding material 1 before preparation is adjusted to 2000 ppm or less, preferably 1000 ppm or less, and more preferably 500 ppm or less, using a hot air dryer or the like. This is because a moisture content exceeding 2000 ppm may cause foaming of the conductive resin film 6 for current collector. To achieve such a low moisture content, the molding material 1 is preferably heated and dried before preparation. Examples of the heating and drying method include known methods such as hot air circulation drying, dehumidified hot air drying, heated vacuum drying, and microwave drying.

[0083] The heat-drying temperature for molding material 1 is preferably in the range of −50°C to +50°C of the glass transition point of the polyether ether ketone resin. Specifically, it is preferably in the range of 80°C to 210°C, preferably 110°C to 190°C, more preferably 130°C to 180°C, and even more preferably 150°C to 170°C. The glass transition point of polyether ether ketone resin is typically in the range of 130°C to 160°C (test method: differential scanning calorimeter), preferably 135°C to 155°C, and more preferably 140°C to 150°C. The heat-drying time for molding material 1 is preferably 2 hours or more, preferably 4 hours or more, and more preferably 8 hours or more. There is no particular upper limit to this heat-drying time, but 24 hours or less is appropriate.

[0084] Once the molding material 1 is prepared, the conductive resin film 6 for a current collector is manufactured using this molding material 1. As a manufacturing method, a melt extrusion method, a calendar molding method, a casting method, or the like can be adopted. Among these manufacturing methods, from the viewpoints of improving the thickness accuracy, productivity, and handleability of the conductive resin film 6 for a current collector, and simplifying the equipment, the melt extrusion method, which allows the conductive resin film 6 for a current collector to be continuously extruded into a strip shape, is optimal.

[0085] The melt extrusion molding method is a method for producing a conductive resin film 6 for a current collector by melt-kneading a molding material 1 using a melt extruder 30 and continuously extruding the conductive resin film 6 for a current collector from a die 33, such as a T-die or a round die, connected to the tip of the melt extruder 30 (see FIG. 3). As shown in FIG. 3, the melt extruder 30 is, for example, a single-screw extruder or a twin-screw extruder, and has a raw material inlet 31 for the molding material 1 at the upper rear. This raw material inlet 31 is connected to an inert gas supply pipe 32 that supplies an inert gas such as helium gas, neon gas, argon gas, krypton gas, or nitrogen gas as needed. The supply of the inert gas from the inert gas supply pipe 32 effectively prevents oxidative degradation, oxygen crosslinking, and thermal crosslinking of the molding material 1.

[0086] The melting temperature during melt-kneading in the melt extruder 30 is not particularly limited as long as it is a temperature that allows melt-kneading and dispersion and does not decompose the polyether ether ketone resin composition 2. However, it is preferably in the range of the melting point of the polyether ether ketone resin to less than the thermal decomposition temperature of the polyether ether ketone resin. Specifically, it is in the range of 360°C to 450°C, preferably 360°C to 420°C, and more preferably 370°C to 400°C. This is because, if the temperature during melt-kneading in the melt extruder 30 is below the melting point of the polyether ketone resin, the polyether ether ketone resin and the carbon-based conductive material 5 cannot be melt-kneaded and dispersed. Conversely, if the temperature is above the thermal decomposition temperature, the polyether ether ketone resin will be decomposed.

[0087] The die 33 is connected to the tip of the melt extruder 30 via a connecting pipe 34, and functions to continuously extrude a strip-shaped conductive resin film for current collector 6 downward. This die 33 is preferably a T-die, which is capable of obtaining a conductive resin film for current collector 6 with excellent thickness precision. A gear pump 35 is preferably attached to the connecting pipe 34 upstream of the die 33. This gear pump 35 functions to transfer the molding material 1 melt-kneaded by the melt extruder 30 to the downstream die 33 at a constant flow rate and with high precision.

[0088] The temperature of the die 33 during extrusion is in the range of from the melting point of the polyether ether ketone resin to the thermal decomposition temperature of the polyether ether ketone resin. Specifically, it is in the range of 360°C to 450°C, preferably 360°C to 420°C, and more preferably 370°C to 400°C. This is because, if the temperature is below the melting point of the polyether ether ketone resin, it is not possible to melt-knead the polyether ether ketone resin composition 2 and the carbon-based conductive material 5 to disperse the carbon-based conductive material 5. Conversely, if the temperature is above the thermal decomposition temperature, it is not preferable because it will lead to decomposition of the polyether ether ketone resin.

[0089] Below the die 33, a pair of opposing pressure rolls 36 are rotatably supported at a distance, and a plurality of cooling rolls 37 arranged in a row and in sliding contact with each other are rotatably supported between the pair of pressure rolls 36, and of the plurality of cooling rolls 37, the upstream cooling roll 37 and the downstream cooling roll 37 each slide against the circumferential surface of the pressure roll 36. Each pressure roll 36 is configured to have a reduced diameter, and each cooling roll 37 is configured to have a larger diameter than the pressure roll 36.

[0090] Of the pair of pressure rolls 36, a winder 39 is installed downstream of the downstream pressure roll 36, which winds the conductive resin film 6 for the current collector onto a rotatable winding tube 38. Between the downstream pressure roll 36 and the winder 39, a slit blade 40 is arranged to be able to rise and fall, which forms a slit in the longitudinal direction of the side of the conductive resin film 6 for the current collector. Between this slit blade 40 and the winder 39, a required number of rotatable tension rolls 41 are supported on shafts to apply tension to the conductive resin film 6 for smooth winding.

[0091] Each pressure roll 36 has a temperature equal to or higher than the glass transition temperature of the polyether ether ketone resin and lower than the melting point of the polyether ether ketone resin, specifically, 140°C or higher and lower than 340°C, preferably 180°C or higher and 300°C or lower, more preferably 200°C or higher and 280°C or lower, and even more preferably 210°C or higher and 240°C or lower.

[0092] The reason why the temperature of the pressure roller 36 is within this range is that if the temperature is below the glass transition point of the polyether ether ketone resin, the relative crystallinity of the current collector conductive resin film 6 cannot be 80% or more. Conversely, if the temperature exceeds the melting point, the current collector conductive resin film 6 may stick to the peripheral surface of the pressure roller 36 and break, or the strength of the current collector conductive resin film 6 may decrease, leading to breakage. Methods for adjusting the temperature of the pressure roller 36 include, for example, a method using a heat medium such as air, water, or oil, a method using an electric heater, and a method using induction heating.

[0093] The peripheral surface of each pressure roll 36 is coated as needed with a rubber layer such as at least natural rubber, isoprene rubber, butadiene rubber, norbornene rubber, acrylonitrile butadiene rubber, nitrile rubber, urethane rubber, silicone rubber, or fluororubber, from the viewpoint of improving the adhesion between the conductive resin film 6 for current collector and the cooling roll 37. An inorganic compound such as silica or alumina is selectively added to this rubber layer. Of these, silicone rubber and fluororubber, which have excellent heat resistance, are preferably selected.

[0094] As the pressure roll 36, a metal elastic roll with a metal surface may be used as needed. When this metal elastic roll is used, it is possible to form a conductive resin film 6 for a current collector with an excellent surface smoothness. Specific examples of this metal elastic roll include a metal sleeve roll, an air roll (product name manufactured by Dymco Corporation), and a UF roll (product name manufactured by Hitachi Zosen Corporation). It is also possible to use a pressure roll 36 whose surface is coated with a fluororesin film such as polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin or tetrafluoroethylene-hexafluoropyrene copolymer (FEP) resin.

[0095] The plurality of cooling rolls 37 are, for example, metal rolls having a larger diameter than the pressure roll 36, and are rotatably supported below the die 33 to sandwich the extruded conductive resin film 6 for a current collector between them and the pressure roll 36. The cooling rolls 37, together with the pressure roll 36, function to cool the conductive resin film 6 for a current collector and control its thickness within a predetermined range. Like the pressure roll 36, the cooling roll 37 is adjusted to a temperature equal to or higher than the glass transition temperature of the polyether ether ketone resin and lower than the melting point of the polyether ether ketone resin, specifically, 140°C or higher and lower than 340°C, preferably 180°C or higher and 300°C or lower, more preferably 200°C or higher and 280°C or lower, and even more preferably 210°C or higher and 240°C or lower, and come into sliding contact with the conductive resin film 6 for a current collector.

[0096] The reason why the temperature of the cooling roll 37 is adjusted to a temperature equal to or higher than the glass transition temperature of the polyether ether ketone resin and lower than the melting point of the polyether ether ketone resin is that if the temperature is lower than the glass transition temperature of the polyether ether ketone resin, the relative crystallinity of the conductive resin film 6 for current collector cannot be made 80% or higher. Conversely, if the temperature exceeds the melting point, the conductive resin film 6 for current collector may stick to the circumferential surface of the pressure roll 36 and break, or the strength of the conductive resin film 6 for current collector may decrease, leading to breakage. Methods for adjusting the temperature and cooling the cooling roll 37 include methods using a heat medium such as air, water, or oil, or an electric heater or induction heating.

[0097] After the molding material 1 is extrusion-molded into a strip-shaped conductive resin film 6 for a current collector, this conductive resin film 6 for a current collector is wound around a pair of pressure-bonding rolls 36, a plurality of cooling rolls 37, a tension roll 41, and a take-up tube 38 of a winder 39, and both side portions of the conductive resin film 6 for a current collector are cut in the longitudinal direction with a slit blade 40, and the film is sequentially wound around the take-up tube 38 of the winder 39, thereby producing a long conductive resin film 6 for a current collector.

[0098] The thickness of the conductive resin film 6 for a current collector produced by cooling with the cooling roll 37 is preferably 5 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less, more preferably 20 μm or more and 200 μm or less, and even more preferably 20 μm or more and 100 μm or less. This is because if the thickness of the conductive resin film 6 for a current collector is less than 5 μm, the tensile strength of the conductive resin film 6 for a current collector will be significantly reduced, making it difficult to produce the conductive resin film 6 for a current collector.

[0099] Conversely, if the thickness of the conductive resin film 6 for current collector exceeds 500 μm, it will hinder weight reduction when used as a current collector for a secondary battery such as a lithium ion secondary battery, a bipolar lithium ion secondary battery, or an all-solid-state battery. The thickness of this conductive resin film 6 for current collector can be measured using various contact thickness gauges. Alternatively, the thickness can be measured by averaging multiple measured values.

[0100] The specific gravity of the conductive resin film 6 for a current collector is 1.60 or less, preferably 1.23 to 1.60, more preferably 1.26 to 1.55, even more preferably 1.28 to 1.50, and even more preferably 1.33 to 1.41. This is because if the specific gravity of the conductive resin film 6 for a current collector is 1.60 or less, particularly less than 1.23, voids or cracks may occur in the conductive resin film 6 for a current collector, causing a problem of reduced mechanical strength, which is undesirable.

[0101] On the other hand, if the specific gravity of the conductive resin film 6 for current collector exceeds 1.60, it will hinder weight reduction when used as a current collector for a secondary battery such as a lithium ion secondary battery, a bipolar lithium ion secondary battery, or an all-solid-state battery. The specific gravity of the conductive resin film 6 for current collector can be measured, for example, by a specific gravity measurement method in accordance with JIS K 7112 Method A.

[0102] The relative crystallinity of the conductive resin film 6 for a current collector is optimally 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 100%. This is because if the relative crystallinity of the conductive resin film 6 for a current collector is less than 80%, problems arise in the mechanical strength, heat resistance, chemical resistance, and solvent resistance of the conductive resin film 6 for a current collector. On the other hand, if the relative crystallinity is more than 80%, the conductive resin film 6 for a current collector can be expected to have sufficient mechanical strength, heat resistance, and chemical resistance to be usable as a conductive resin film 6 for a current collector.

[0103] The crystallinity of the conductive resin film 6 for a current collector can be expressed by the relative crystallinity, which is calculated by the following formula based on the results of thermal analysis measured at a heating rate of 10°C / min using a differential scanning calorimeter. Relative crystallinity (%) = {1-(ΔHc / ΔHm)} × 100 ΔHc: Heat quantity at the recrystallization peak of the conductive resin film for the current collector (J / g) ΔHm: Heat of melting peak of conductive resin film for current collector (J / g)

[0104] The mechanical properties of the conductive resin film 6 for current collector can be expressed by the tensile modulus, tensile elongation at break, and maximum tensile strength. The tensile modulus of the conductive resin film 6 for current collector, as measured in accordance with JIS K 7127, is preferably 2000 MPa or more, preferably 3000 MPa or more, more preferably 3500 MPa or more, and even more preferably 4000 MPa or more. There are no particular restrictions on the upper limit of this tensile modulus, but in practical terms, it is preferably 10000 MPa or less.

[0105] This is because if the tensile modulus is less than 2000 MPa, when the conductive resin film 6 for current collectors is used as a current collector of a secondary battery, the conductive resin film 6 for current collectors will have poor rigidity, and may be deformed during the coating process of the positive electrode active material or the negative electrode active material, or during assembly of the secondary battery. On the other hand, if the tensile modulus exceeds 10000 MPa, the conductive resin film 6 for current collectors will have too great rigidity and will not be able to be wound up.

[0106] The tensile elongation at break of the conductive resin film 6 for current collector, as measured in accordance with JIS K 7127, is preferably 10% or more, preferably 15% or more, more preferably 20% or more, and even more preferably 25% or more. This is because if the tensile elongation at break of the conductive resin film 6 for current collector is less than 10%, the conductive resin film 6 for current collector has poor toughness and may crack during its manufacture. Furthermore, this is because the conductive resin film 6 for current collector may crack during the coating process of the positive electrode active material or negative electrode active material of the conductive resin film 6 for current collector. The upper limit of this tensile elongation at break is not particularly limited, but is preferably 500% or less. This is because if it exceeds 500%, the conductive resin film 6 for current collector may stretch during the coating process of the positive electrode active material or negative electrode active material of the conductive resin film 6 for current collector.

[0107] The maximum tensile strength of the conductive resin film 6 for a current collector, as measured in accordance with JIS K 7127, is preferably 60 MPa or more, preferably 70 MPa or more, more preferably 90 MPa or more, and even more preferably 100 MPa or more. This is because, if the maximum tensile strength of the conductive resin film 6 for a current collector is less than 60 MPa, the conductive resin film 6 for a current collector will have poor toughness and will crack during the production of the conductive resin film 6 for a current collector. In addition, the conductive resin film 6 for a current collector will crack during the coating process of the positive electrode active material or negative electrode active material of the conductive resin film 6 for a current collector.

[0108] Although the upper limit of the tensile elongation at break is not particularly limited, it is preferably 500 MPa or less. This is because if it exceeds 500 MPa, the cutting ability with the slit blade 40 decreases during the production of the conductive resin film 6 for a current collector, which undesirably reduces the production speed of the long conductive resin film 6 for a current collector.

[0109] The conductivity of the conductive resin film 6 for current collector can be evaluated by the resistance value measured when a pressure of 1 MPa is applied in the thickness direction. The resistance value when a pressure of 1 MPa is applied in the thickness direction is 1000 mΩ cm. 2 Less than or equal to 800 mΩ·cm, preferably 2 Less than or equal to 600 mΩ·cm, preferably 2 or less, more preferably 500 mΩ·cm 2 The optimum value is as follows. There are no particular restrictions on the lower limit of the resistance value when measured with a pressure of 1 MPa applied in the thickness direction, but in practice it should be 1 mΩ cm. 2 That's all.

[0110] This is because the resistance of the conductive resin film 6 for the current collector is 1000 mΩ cm 2 If the resistance exceeds 1 mΩ cm, the energy density will decrease when used as a current collector for a secondary battery. 2 If it is less than this, a large amount of carbon-based conductive material 5 must be added, which makes the resulting conductive resin film 6 for current collector brittle, causing the problem of the conductive resin film 6 for current collector cracking during assembly of the secondary battery.

[0111] The chemical resistance of the conductive resin film 6 for a current collector can be evaluated by immersing the conductive resin film 6 for a current collector in N-methyl-2-pyrrolidone and an electrolyte solution and measuring the change in mass. From the viewpoint of improving chemical resistance and solvent resistance, the rate of mass change when the conductive resin film 6 for a current collector is immersed in N-methyl-2-pyrrolidone and an electrolyte solution is optimally 2.0% or less, preferably 0.0% to 2.0%, more preferably 0.0% to 1.0%, and even more preferably 0.0% to 0.1%.

[0112] The electrolyte is an organic electrolyte solution containing a lithium salt dissolved in an organic solvent as a solute. Examples of organic solvents for this electrolyte include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC), chain carbonates such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), cyclic ethers such as tetrahydrofuran (THF) and 1,3-dioxolane (DOXL), chain ethers such as 1,2-dimethoxyethane (DEM) and 1,2-diethoxyethane (DEE), cyclic esters such as γ-butyrolactone (GBL), and chain esters such as methyl acetate (MA).

[0113] Examples of lithium salts include lithium perchlorate (LiClO4), lithium borofluoride (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2), and lithium tris(trifluoromethanesulfonyl)methide (LiC(CF3SO2)3).

[0114] If N-methyl-2-pyrrolidone or the electrolyte remains in the conductive resin film for current collector 6, the N-methyl-2-pyrrolidone or the electrolyte may seep into the secondary battery during operation, causing problems, so care must be taken. Also, care must be taken because the electrolyte of the secondary battery may seep into the current collector, reducing the charge / discharge cycle.

[0115] The molded conductive resin film 6 for current collector may be used as is, or may be further subjected to heat compression molding. Heat compression molding of the conductive resin film 6 for current collector can lower the resistance value and increase the conductivity, and can reduce the amount of carbon-based conductive material 5 used, thereby reducing costs.

[0116] When the conductive resin film 6 for a current collector is subjected to heat compression molding, the conductive resin film 6 for a current collector is sandwiched between a plurality of metal plates, metal rolls, or metal belts that have been heated to a temperature not lower than the melting point of the polyetheretherketone resin but lower than the thermal decomposition temperature of the polyetheretherketone resin, specifically not lower than the melting point of the polyetheretherketone resin +10°C and not higher than the thermal decomposition temperature of the polyetheretherketone resin, specifically not lower than the melting point of the polyetheretherketone resin +100°C, preferably not lower than the melting point of the polyetheretherketone resin +20°C and not higher than the melting point of the polyetheretherketone resin +80°C, more preferably not lower than the melting point of the polyetheretherketone resin +30°C and not higher than the melting point of the polyetheretherketone resin +60°C, and even more preferably not lower than the melting point of the polyetheretherketone resin +30°C and not higher than the melting point of the polyetheretherketone resin +50°C, and a pressure of 0.5 kgf / cm is applied to the projected area of ​​the conductive resin film 6 for a current collector. 2 More than 100kgf / cm 2 The pressure is applied to the resin, and the pressure is maintained for 0.5 seconds to 300 seconds, and the resin is immediately cooled to a temperature below the glass transition point of the polyether ether ketone resin.

[0117] According to the above, polyether ether ketone resin, which has excellent lightness, mechanical properties, chemical resistance, and heat resistance and low water absorption, is selected as the thermoplastic resin of molding material 1 to manufacture conductive resin film 6 for current collector, so that even if conductive resin film 6 for current collector is used as a current collector, electrolyte components do not penetrate into conductive resin film 6 for current collector, effectively eliminating the risk of deterioration in charge / discharge cycle characteristics. Furthermore, because polyether ether ketone resin is used instead of fluororesin, no special steel materials or equipment are required for molding, and significant cost reductions in the current collector can be expected.

[0118] Furthermore, by using first and second polyether ether ketone resins 3 and 4 with different apparent melt viscosities, there is no need to use two different resins, eliminating the risk of current collector peeling. Furthermore, there is no risk of curling due to differences in expansion coefficients caused by water absorption after manufacturing, or peeling of the current collector between the first and second conductive layers. Furthermore, when the carbon-based conductive material 5 is carbon nanotubes, it is chemically stable and can further reduce the weight of secondary batteries. Furthermore, since the thickness of the conductive resin film for current collector 6 is 5 μm or more and 500 μm or less, a decrease in the tensile strength of the conductive resin film for current collector 6 is prevented, which is expected to significantly reduce the weight of secondary battery current collectors.

[0119] In addition, since the specific gravity of the conductive resin film 6 for current collector is 1.60 or less, it can contribute to a significant weight reduction of the secondary battery and the current collector. Furthermore, when a pressure of 1 MPa is applied to the conductive resin film 6 for current collector in the thickness direction, the resistance value is 1 mΩ cm. 2 More than 1000mΩ cm 2 Since the electrical conductivity is low at or below 100 kJ / cm 2 , even when the conductive resin film 6 for current collector is used as a current collector for a secondary battery, it is possible to prevent a decrease in energy density.

[0120] The polyether ketone resin in the above embodiment may be in any form, including powder, granules, blocks, powder, pellets, etc. The conductive resin film 6 for a current collector has a specific gravity of 1.33 to 1.41 as measured in accordance with JIS K7112 Method A, a relative crystallinity of 95% to 100%, a tensile modulus of 3683 MPa to 5274 MPa as measured in accordance with JIS K 7127, a tensile elongation at break of 24% to 45% as measured in accordance with JIS K 7127, a maximum tensile strength of 94 MPa to 126 MPa as measured in accordance with JIS K 7127, and a resistance of 107 mΩ cm as measured under a pressure of 1 MPa in the thickness direction. 2 More than 227mΩ cm 2 The following is also fine.

[0121] In order to utilize the properties of carbon nanotubes, a mixture of carbon nanotubes having different outer diameters and lengths may be used. Furthermore, a single cooling roll 37 may be rotatably supported between a pair of pressure bonding rolls 36. [Example]

[0122] EXAMPLES Hereinafter, examples of a conductive resin film for a current collector of a secondary battery according to the present invention and a method for producing the same will be described together with comparative examples. Example 1 First, to prepare a polyetheretherketone resin composition comprising a plurality of polyetheretherketone resins having different apparent melt viscosities, a commercially available polyetheretherketone resin (manufactured by Victrex, product name: Victrex Granules 90G, hereinafter abbreviated as "90G") was prepared as the first polyetheretherketone resin, and a commercially available polyetheretherketone resin (manufactured by Victrex, product name: Victrex Granules 381G, hereinafter abbreviated as "381G") was prepared as the second polyetheretherketone resin.

[0123] These first and second polyether ether ketone resins were each pulverized by freeze-pulverization. The pulverized first and second polyether ether ketone resins were weighed out in the composition mass ratios shown in Table 1, charged into a stirring mixer, and stirred and mixed to prepare polyether ether ketone resin compositions with different apparent melt viscosities. The polyether ether ketone resin will hereinafter be abbreviated as "PEEK resin."

[0124] The apparent melt viscosity of the PEEK resin was measured using a flow tester (Shimadzu Corporation, product name: Shimadzu Flow Tester CFT-500D). Specifically, the PEEK resin was dried in advance in a hot air dryer at 160°C for 12 hours, and 1.5 cm of PEEK resin was 3 The mixture was packed into a cylinder at 375°C equipped with a die (diameter: 1 mm, length: 10 mm), and a 1.0 cm2 area was placed on top of the cylinder. 2A plunger was attached, and when the cylinder temperature reached 375°C, it was preheated for 5 minutes. Immediately after this preheating, a load of 50 kgf was applied, causing the PEEK resin to melt and flow out, and its apparent melt viscosity was measured. The apparent melt viscosity was measured in the same manner as below. The apparent melt viscosity at 90G was 109 Pa·s, and at 381G it was 879 Pa·s.

[0125] After preparing the PEEK resin composition, the PEEK resin composition and multi-walled carbon nanotubes, which are a carbon-based conductive material, were weighed out to obtain the mass ratio shown in Table 1. The PEEK resin and multi-walled carbon nanotubes were then placed in a mixer to prepare a stirred mixture. NC7000 (product name manufactured by Nanosil Co., Ltd., hereinafter abbreviated as "NC7000") was used as the multi-walled carbon nanotubes.

[0126] Once the stirred mixture was prepared, it was fed into a co-rotating twin-screw extruder equipped with a vacuum pump and melt-kneaded under reduced pressure. The melt-kneaded mixture was extruded into a rod shape from the die at the tip of the co-rotating twin-screw extruder, cooled with water, and cut to prepare pellet-shaped molding materials. The co-rotating twin-screw extruder was a φ25mm, L / D=41 type. The stirred mixture was melt-kneaded under conditions of a cylinder temperature of 300-370°C and a die temperature of 370°C, with the vent on the raw material inlet side of the co-rotating twin-screw extruder open and the vent on the die side degassing under reduced pressure, to prepare molding materials. The temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was measured to be 376°C. Once the molding material was prepared, the apparent melt viscosity of this molding material was measured using the same method as above.

[0127] The prepared molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for at least 12 hours. After confirming that the moisture content of the dried molding material was 300 ppm or less, the molding material was placed in a φ40 mm single-screw extruder and continuously extruded through a 900 mm wide T-die to form a strip of conductive resin film for current collectors with a relative crystallinity of 100%. The moisture content of the molding material was confirmed by Karl Fischer titration using a trace moisture analyzer (Mitsubishi Chemical Corporation, product name: CA-100). The moisture content of the molding material was subsequently measured using the same method.

[0128] The single-screw extruder had an L / D ratio of 25, a compression ratio of 2.5, and a full-flight screw. The temperature of the single-screw extruder was adjusted to 360-395°C, the temperature of the T-die to 395°C, and the temperature of the connecting pipe connecting the single-screw extruder to the T-die to 395°C. The temperature of the molten molding material was measured from the resin temperature at the inlet of the T-die and found to be 398°C. When the molding material was introduced into the single-screw extruder, nitrogen gas was supplied at a rate of 15 L / min.

[0129] After the conductive resin film for a current collector was formed, this conductive resin film for a current collector was sequentially wound around a pair of silicone rubber pressure rolls (210°C) and a cooling roll (220°C) as shown in Figure 3, and a take-up tube of a 6-inch take-up machine located downstream of these, and was sandwiched between the pressure roll and a metal roll, and the continuous conductive resin film for a current collector was sequentially taken up around the take-up tube to produce a conductive resin film for a current collector having a length of 100 m and a width of 150 mm.

[0130] Once the conductive resin film for current collectors was manufactured, the presence or absence of die buildup during manufacturing of the conductive resin film for current collectors, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for current collectors were evaluated, and the results are summarized in Table 1. The mechanical properties of the conductive resin film for current collectors were evaluated by the tensile modulus, tensile elongation at break, and maximum tensile strength, chemical resistance was evaluated by the change in mass before and after immersion in N-methyl-2-pyrrolidone and electrolyte, and conductivity was evaluated by the conductivity of the conductive film before and after immersion in electrolyte.

[0131] -Film used in the current collector is made of conductive resin. Regarding the die resin generated during the production of the conductive resin film for current collector, after producing 100 m of conductive resin film for current collector, the vicinity of the lip of the T-die was visually observed.

[0132] Thickness of conductive resin film for current collector The thickness of the conductive resin film for the current collector was measured using a micrometer (Mitutoyo Corporation, product name: Coolant-proof micrometer, model number MDC-25PJ). Measurements were taken at 10 random locations in the width direction (the direction perpendicular to the extrusion direction (hereinafter abbreviated as "TD")) of the conductive resin film for the current collector, and the average value was taken as the film thickness.

[0133] Specific gravity of conductive resin film for current collector The specific gravity of the conductive resin film for current collector was measured in an environment of 23°C in accordance with the standard of JIS K 7112 Method A.

[0134] Relative crystallinity of conductive resin film for current collector The relative crystallinity of the conductive resin film for current collectors was measured by weighing out approximately 5 mg of a measurement sample from the conductive resin film for current collectors and using a differential scanning calorimeter (manufactured by SII Nanotechnologies, Inc., product name: EXSTAR7000 series X-DSC7000) at a heating rate of 10°C / min over a measurement temperature range of 20°C to 380°C. The heat quantity (J / g) of the melting peak and the heat quantity (J / g) of the recrystallization peak obtained at this time were used to calculate the crystallinity using the following formula.

[0135] Relative crystallinity (%) = {1-(ΔHc / ΔHm)} × 100 ΔHc: Heat quantity at the recrystallization peak of the conductive resin film for the current collector (J / g) ΔHm: Heat of melting peak of conductive resin film for current collector (J / g)

[0136] Mechanical properties of conductive resin film for current collectors The mechanical properties of the conductive resin film for current collector were evaluated in terms of tensile modulus, elongation at break, and maximum tensile strength at 23°C. The mechanical properties were measured in the extrusion direction (hereinafter abbreviated as "MD") and TD. The measurements were performed in accordance with JIS K 7127 under conditions of a pulling speed of 50 mm / min, a temperature of 23°C ± 2°C, and a relative humidity of 50 RH ± 5% RH.

[0137] Chemical resistance of conductive resin film for current collectors The chemical resistance of the conductive resin film for current collectors was evaluated by immersing it in N-methyl-2-pyrrolidone (NMP) and electrolyte and measuring the mass change. To evaluate the mass change of the conductive resin film for current collectors, the conductive resin film for current collectors was cut into a size of 5.5 cm MD x 5.5 cm TD and weighed [W0]. This conductive resin film for current collectors, along with 5 g of NMP or 5 g of electrolyte, was placed in a PET / AL / PE flat bag (manufactured by Nippon Seisaku Co., Ltd.: trade name Lamizip) and heat-sealed. The electrolyte used was an electrolyte for lithium primary / secondary / polymer batteries and lithium-ion capacitors (manufactured by Kishida Chemical Co., Ltd.: trade name LiPF6, molarity 1 mol / L, solvent EC:DEC (3:7) V / V%).

[0138] After sealing with heat sealing, the PET / AL / PE flat bag was left to stand in a hot air oven heated to 50°C for 15 days. After leaving it to stand, the conductive resin film for the current collector was removed from the PET / AL / PE flat bag and washed with ethanol. This conductive resin film for the current collector was left to stand in a hot air oven heated to 50°C for 24 hours, and after leaving it to stand, it was left to stand in a glass desiccator containing a desiccant (manufactured by Ozone Chemical Co., Ltd.: product name OZO-C) in an environment of 23°C for 24 hours. Thereafter, the conductive resin film for the current collector was weighed [W1], and the mass change rate was calculated using the following formula and evaluated as A to F.

[0139] Mass change rate (%) = {(W1-W0) / W0} x 100 W0: Initial mass of conductive resin film for current collector [g] W1: Mass of the conductive resin film for the current collector after immersion in NMP or electrolyte [g] A: When the mass change rate is between 0.0% and 0.1% B: Mass change rate is over 0.1% and 1.0% or less C: Mass change rate is over 1.0% and 2.0% or less D: Mass change rate is over 2.0% and 5.0% or less E: Mass change rate is over 5.0% and 10% or less

[0140] Conductivity of conductive resin film for current collector The conductivity of the conductive resin film for current collectors was evaluated by the resistance value in the thickness direction. To evaluate the resistance value in the thickness direction (Rc), a test piece was prepared by cutting the conductive resin film for current collectors to a size of 5.5 cm MD × 5.5 cm TD, as shown in Figures 4 and 5. The conductive resin film for current collectors was sandwiched between a pair of 5.0 cm × 5.0 cm carbon paper strips, which were then sandwiched between a pair of gold-plated electrodes. A direct current was applied, and a pressure of 1 MPa was applied from above. The resistance value (R0) was measured after 1 minute using a resistance meter, and the resistance value was calculated using the following formula:

[0141] Rc=R1×S R1 = R0 - (resistance of two sheets of carbon paper) S: Carbon paper

[0142] The carbon paper used was a SIGRACET Gas Diffusion Media type GDL24B (manufactured by SGL GROUP, product name). The resistance meter used was a Milliohm HiTester 3540 (manufactured by Hioki E.E. Corporation, product name). The resistance value (Rc) through the thickness direction was measured before and after a chemical resistance test using a conductive resin film and an electrolyte for lithium primary and secondary polymer batteries and lithium ion capacitors (manufactured by Kishida Chemical Co., Ltd., product name: electrolyte LiPF6, molar concentration 1 mol / L, solvent EC:DEC (3:7) V / V%). The measurements were taken in an environment with a temperature of 23°C ± 2°C and a relative humidity of 50 ± 5% RH.

[0143] Example 2 The composition mass ratio of the pulverized first and second PEEK resins of Example 1, which had different apparent melt viscosities, was changed as shown in Table 1, and a PEEK resin composition was prepared in the same manner as in Example 1. After the PEEK resin composition was prepared, this PEEK resin composition and multi-walled carbon nanotubes, which are carbon-based conductive materials, were weighed out to obtain the mass ratio shown in Table 1, and then the PEEK resin and multi-walled carbon nanotubes were charged into a mixer to prepare a stirred mixture. After preparing the stirred mixture, a pellet-shaped molding material was prepared in the same manner as in Example 1.

[0144] The temperature during melt kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 375° C. The multi-walled carbon nanotubes used were the NC7000 used in Example 1. After preparing the molding material, the apparent melt viscosity of this molding material was measured in the same manner as in Example 1.

[0145] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and was found to be 398°C. After molding, a conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of this conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of this conductive resin film for a current collector were evaluated and the results are summarized in Table 1.

[0146] Example 3 The procedure was basically the same as in Example 1, except that the PEEK resin composition used was changed to Victrex Granules 151G (product name of Victrex Corporation; hereinafter abbreviated as "151G"), which was prepared by pre-freezing and crushing the 90G PEEK resin used in Example 1. 151G and the 381G used in Example 1 were weighed out in the compositional mass ratios shown in Table 1, charged into a stirring mixer, and stirred and mixed to prepare PEEK resin compositions with different apparent melt viscosities. The apparent melt viscosity of 151G was measured using the same method as in Example 1 and was found to be 192 Pa s.

[0147] After preparing the PEEK resin composition, the PEEK resin composition and multi-walled carbon nanotubes, which are a carbon-based conductive material, were weighed out to obtain the mass ratio shown in Table 1. The PEEK resin and multi-walled carbon nanotubes were then charged into a mixer to prepare a stirred mixture. The multi-walled carbon nanotubes used were the NC7000 used in Example 1. After preparing the molding material, the apparent melt viscosity of the molding material was measured using the same method as in Example 1.

[0148] Next, a molding material was prepared in the same manner as in Example 1. The temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 375°C.

[0149] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and was found to be 398°C. After molding, the conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for a current collector were evaluated and the results are summarized in Table 1.

[0150] Example 4 The process was basically the same as in Example 1, but PEEK resin compositions with different apparent melt viscosities were prepared by weighing out 151G, the PEEK resin used in Example 3, and 381G, the PEEK resin used in Example 1, in the composition mass ratios shown in Table 1, putting them into a stirring mixer, and stirring and mixing them.

[0151] After preparing the PEEK resin composition, the PEEK resin composition and multi-walled carbon nanotubes, which are a carbon-based conductive material, were weighed out to obtain the mass ratio shown in Table 1, and then the PEEK resin and multi-walled carbon nanotubes were charged into a mixer to prepare a stirred mixture. The multi-walled carbon nanotubes used in Example 1 were changed from NC7000 in Example 1 to FloTube 9000 (product name, manufactured by CNano Technology, hereinafter abbreviated as "9000"). The PEEK resin composition and multi-walled carbon nanotubes were weighed out to obtain the composition mass ratio shown in Table 1, and a stirred mixture was prepared.

[0152] Next, a molding material was prepared in the same manner as in Example 1. The temperature during melt kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 380° C. After the molding material was prepared, the apparent melt viscosity of this molding material was measured in the same manner as in Example 1.

[0153] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and found to be 400°C. After molding, a conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for a current collector were evaluated and the results are summarized in Table 1.

[0154] [Table 1]

[0155] Example 5 The procedure was basically the same as in Example 1, except that the PEEK resin 381G used in Example 1 was replaced with pre-frozen and crushed Victrex Granules 450G (product name of Victrex Corporation; hereinafter abbreviated as "450"), which was weighed out to the composition mass ratio shown in Table 2 relative to the 90G used in Example 1, and then charged into a stirring mixer and stirred and mixed to prepare PEEK resin compositions with different apparent melt viscosities. The apparent melt viscosity of 450G was measured in the same manner as in Example 1 and was found to be 1067 Pa s.

[0156] After preparing the PEEK resin composition, the PEEK resin composition and multi-walled carbon nanotubes, which are a carbon-based conductive material, were weighed out to obtain the mass ratio shown in Table 2. The PEEK resin and multi-walled carbon nanotubes were then placed in a mixer to prepare a stirred mixture. The multi-walled carbon nanotubes used were NC7000, the same as in Example 1.

[0157] Next, a molding material was prepared in the same manner as in Example 1. The temperature during melt kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 375° C. After the molding material was prepared, the apparent melt viscosity of this molding material was measured in the same manner as in Example 1.

[0158] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and was found to be 395°C. After molding, the conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for a current collector were evaluated and are shown in Table 2.

[0159] Example 6 The process was basically the same as in Example 1, but the 90G used in Example 1 and the 450G used in Example 5 were weighed out to achieve the composition mass ratio shown in Table 2, and then charged into a stirring mixer and stirred and mixed to prepare PEEK resin compositions with different apparent melt viscosities. After preparing the PEEK resin composition, this PEEK resin composition and multi-walled carbon nanotubes, which are a carbon-based conductive material, were weighed out to achieve the mass ratio shown in Table 2, and then the PEEK resin and multi-walled carbon nanotubes were charged into the mixer to prepare a stirred mixture. The multi-walled carbon nanotubes used were NC7000, the same as in Example 1.

[0160] Next, a molding material was prepared in the same manner as in Example 1. The temperature during melt kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 375° C. After the molding material was prepared, the apparent melt viscosity of this molding material was measured in the same manner as in Example 1.

[0161] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and was found to be 395°C. After molding, the conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for a current collector were evaluated and are shown in Table 2.

[0162] Example 7 The process was basically the same as in Example 1, but the 151G used in Example 3 and the 450G used in Example 5 were weighed out to achieve the composition mass ratio shown in Table 2, and then charged into a stirring mixer and stirred and mixed to prepare PEEK resin compositions with different apparent melt viscosities. After preparing the PEEK resin composition, this PEEK resin composition and multi-walled carbon nanotubes, which are a carbon-based conductive material, were weighed out to achieve the mass ratio shown in Table 2, and then the PEEK resin and multi-walled carbon nanotubes were charged into the mixer to prepare a stirred mixture. The 9000 multi-walled carbon nanotubes used in Example 4 were used.

[0163] Next, a molding material was prepared in the same manner as in Example 1. The temperature during melt kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 376° C. After the molding material was prepared, the apparent melt viscosity of this molding material was measured in the same manner as in Example 1.

[0164] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and was found to be 398°C. After molding, the conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for a current collector were evaluated and are shown in Table 2.

[0165] Example 8 The procedure was basically the same as in Example 1, except that the 151G used in Example 3 and the 450G used in Example 5 were weighed out to the composition mass ratio shown in Table 2, charged into a stirring mixer, and stirred and mixed to prepare PEEK resin compositions with different apparent melt viscosities. After preparing the PEEK resin composition, this PEEK resin composition and multi-walled carbon nanotubes, a carbon-based conductive material, were weighed out to the mass ratio shown in Table 2, and then the PEEK resin and multi-walled carbon nanotubes were charged into a mixer to prepare a stirred mixture. The 9000 multi-walled carbon nanotubes used in Example 4 were used. After preparing the molding material, the apparent melt viscosity of this molding material was measured using the same method as in Example 1.

[0166] Next, a molding material was prepared in the same manner as in Example 1. The temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 380°C.

[0167] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and was found to be 395°C. After molding, the conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for a current collector were evaluated and are shown in Table 2.

[0168] [Table 2]

[0169] Comparative Example 1 The process was basically the same as in Example 1, but the first and second PEEK resins used in Example 1, which had different apparent melt viscosities, were weighed out in composition mass ratios outside the range of the present invention shown in Table 3, and then charged into a stirring mixer and stirred and mixed to prepare multiple PEEK resin compositions with different apparent melt viscosities.

[0170] Next, the PEEK resin composition was prepared into a molding material in the same manner as in Example 1. That is, the PEEK resin composition and multi-walled carbon nanotubes were weighed in the composition mass ratio shown in Table 3 and charged into a stirring mixer to prepare a stirred mixture, and this stirred mixture was prepared into a pellet-shaped molding material in the same manner as in Example 1. The temperature during melt kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was measured to be 376°C. After the molding material was prepared, the apparent melt viscosity of this molding material was measured in the same manner as in Example 1.

[0171] Next, the prepared molding material was used to mold a conductive resin film for a current collector having a relative crystallinity of 100% into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die, and it was 398°C. After molding, a conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of this conductive resin film for a current collector were evaluated and the results are summarized in Table 3.

[0172] Comparative Example 2 First, the PEEK resin used in Example 3 and the PEEK resin used in Example 1 were weighed out in a composition mass ratio outside the range of the present invention shown in Table 3, and then charged into a stirring mixer and stirred and mixed to prepare multiple PEEK resin compositions with different apparent melt viscosities.The PEEK resin compositions and multi-walled carbon nanotubes were then weighed out in the composition mass ratio shown in Table 3 and charged into a stirring mixer to prepare a stirred mixture, and this stirred mixture was prepared into a pellet-shaped molding material using the same method as in Example 1.

[0173] The temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 375° C. After preparing the molding material, the apparent melt viscosity of this molding material was measured in the same manner as in Example 1.

[0174] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and was found to be 397°C. After molding, the conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for a current collector were evaluated and the results are summarized in Table 3.

[0175] Comparative Example 3 The PEEK resin composition used in Example 5 and the multi-walled carbon nanotubes used in Example 1 were weighed out in a composition mass ratio outside the range of the present invention shown in Table 3 and charged into a stirring mixer to prepare a stirred mixture, and this stirred mixture was prepared into a pellet-shaped molding material by the same method as in Example 1. The temperature during melt kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was measured to be 375°C. After preparing the molding material, the apparent melt viscosity of this molding material was measured by the same method as in Example 1.

[0176] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and was found to be 396°C. After molding, the conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for a current collector were evaluated and the results are summarized in Table 3.

[0177] Comparative Example 4 The PEEK resin composition used in Example 7 and the multi-walled carbon nanotubes used in Example 4 were weighed out in a composition mass ratio outside the range of the present invention shown in Table 3 and charged into a stirring mixer to prepare a stirred mixture, and this stirred mixture was prepared into a pellet-shaped molding material by the same method as in Example 1. The temperature during melt kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was measured to be 381°C. After preparing the molding material, the apparent melt viscosity of this molding material was measured by the same method as in Example 1.

[0178] Next, the prepared molding material was used to mold a conductive resin film for a current collector into a strip shape in the same manner as in Example 1. The temperature of the molten molding material was measured from the resin temperature at the entrance of a T-die and was found to be 396°C. After molding, the conductive resin film for a current collector was produced in the same manner as in Example 1, and the generation of die boogers during the production of the conductive resin film for a current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for a current collector were evaluated and the results are summarized in Table 3.

[0179] Comparative Example 5 A conductive resin film for a current collector having a relative crystallinity of 35% was molded using a molding material comprising the polyether ether ketone resin composition and multi-walled carbon nanotubes used in Example 1. The molding of the conductive resin film for a current collector was carried out in the same manner as in Example 1. However, the temperatures of the pressure roll and the chill roll were changed from 220°C for the pressure roll and 210°C for the chill roll in Example 1 to 100°C for the pressure roll and 100°C for the chill roll in Comparative Example 5, and the conductive resin film for a current collector was molded into a strip shape. The temperature of the molten molding material was measured from the resin temperature at the entrance of the T-die and was found to be 398°C.

[0180] After the conductive resin film for current collector was formed, the generation of die deposits during the production of the conductive resin film for current collector, as well as the thickness, specific gravity, relative crystallinity, mechanical properties, chemical resistance, and conductivity of the conductive resin film for current collector were evaluated and the results are shown in Table 3.

[0181] [Table 3]

[0182] 〔evaluation〕 In Examples 1 to 7, good results were obtained in terms of the mechanical properties, chemical resistance, and conductivity of the conductive resin film for current collector. In Example 8, the chemical resistance of the conductive resin film for current collector was slightly reduced, but practically sufficient results were obtained.

[0183] In contrast, in Comparative Example 1, the composition mass ratio of the first PEEK resin was outside the range of the present invention, resulting in a significant deterioration in the conductivity of the conductive resin film for a current collector. Furthermore, in Comparative Example 2, the composition mass ratio of the second PEEK resin was outside the range of the present invention, resulting in a significant deterioration in the tensile elongation at break of the conductive resin film for a current collector. In Comparative Example 3, the amount of carbon-based conductive material added was outside the range of the present invention, resulting in a significant deterioration in the conductivity of the conductive resin film for a current collector. Furthermore, in Comparative Example 4, the amount of carbon-based conductive material added was outside the range of the present invention, resulting in a deterioration in the chemical resistance as well as the tensile elongation at break of the conductive resin film for a current collector. Furthermore, in Comparative Example 5, the relative crystallinity was outside the range of the present invention, resulting in a significant deterioration in the chemical resistance of the conductive resin film for a current collector, raising doubts about its practical utility. [Industrial Applicability]

[0184] The conductive resin film for a current collector of a secondary battery and the method for producing the same according to the present invention are used in the field of producing secondary batteries such as nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium ion secondary batteries, and all-solid-state batteries. [Explanation of symbols]

[0185] 1 Molding material 2. Polyether ether ketone resin composition 3. First polyether ether ketone resin 4. Second polyether ether ketone resin 5 Carbon-based conductive materials 6. Conductive resin film for current collectors 10 Melt kneader 20 Melt kneader 30 Melt extrusion molding machine 33 Dice 36 Crimping roll 37 Cooling Roll 38 Winding tube 39 Winder

Claims

1. 1. A conductive resin film for a current collector of a secondary battery, comprising: 100 parts by mass of a polyether ether ketone resin composition containing at least a plurality of polyether ether ketone resins having different apparent melt viscosities; and 5 parts by mass or more and 30 parts by mass or less of a carbon-based conductive material, the conductive resin film having a relative crystallinity of 80% or more.

2. The thickness is 5 μm or more and 500 μm or less, the mass change rate when immersed in N-methyl-2-pyrrolidone and electrolyte is 0.0% or more and 2.0% or less, and the resistance value when measured by applying a pressure of 1 MPa in the thickness direction is 1 mΩ cm 2 More than 1000mΩ・cm 2 2. The conductive resin film for a current collector of a secondary battery according to claim 1, wherein:

3. the plurality of polyether ether ketone resins include first and second polyether ether ketone resins, and the composition mass ratios of the first and second polyether ether ketone resins are 5% by mass or more and 60% by mass or less for the first polyether ether ketone resin and 40% by mass or more and 95% by mass or less for the second polyether ether ketone resin; the first polyether ether ketone resin has an apparent melt viscosity of 50 Pa s or more and 500 Pa s or less under conditions of a temperature of 375°C and a load of 50 kgf; 3. The conductive resin film for a current collector of a secondary battery according to claim 1, wherein the second polyether ether ketone resin has an apparent melt viscosity of more than 500 Pa·s and not more than 2500 Pa·s under conditions of a temperature of 375°C and a load of 50 kgf.

4. The apparent melt viscosity ratio of the first and second polyether ether ketone resins under the conditions of a temperature of 375°C and a load of 50 kgf is:

4. The conductive resin film for a current collector of a secondary battery according to claim 3, wherein the apparent melt viscosity of the second polyether ether ketone resin / the apparent melt viscosity of the first polyether ether ketone resin is equal to or greater than 3 / 1 and equal to or less than 15 / 1.

5. A method for producing the conductive resin film for a current collector of a secondary battery according to claim 1 or 2, comprising: A molding material comprising 100 parts by mass of a polyether ether ketone resin composition containing at least a plurality of polyether ether ketone resins having different apparent melt viscosities from each other and 5 parts by mass or more and 30 parts by mass or less of a carbon-based conductive material is melt-kneaded; A method for producing a conductive resin film for a current collector of a secondary battery, comprising extruding a molding material through a die into a conductive resin film for a current collector, and then cooling the film by sandwiching the film between a pressure roll and a cooling roll, both of which have temperatures equal to or higher than the glass transition temperature of the polyether ether ketone resin but lower than the melting point of the polyether ether ketone resin, to thereby produce a conductive resin film for a current collector having a relative crystallinity of 80% or higher.

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