Polymer solid electrolyte, electrode, battery, and method for manufacturing polymer solid electrolyte film

Abstract

To provide a polymer solid electrolyte with excellent ion conductivity and heat resistance.SOLUTION: The present invention relate to a polymer solid electrolyte containing an alkali metal salt and polyether nitrile.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polymer solid electrolyte, an electrode, a battery, and a method for manufacturing a polymer solid electrolyte film.

Background Art

[0002] In recent years, lithium-ion secondary batteries (LIBs) have been used in various applications such as portable devices such as smartphones and mobile phones, hybrid vehicles, electric vehicles, and household power storage devices, and research and development related to them have been actively conducted.

[0003] In particular, in applications such as electric vehicles, there is a strong demand for improving the safety of LIBs. Conventional LIBs use a flammable electrolyte solution, so combustion or explosion of the battery may occur. Therefore, research on solid electrolytes that can contribute to improving safety has been active.

[0004] A solid electrolyte is a solid that easily conducts ions and is generally classified into oxide-based, sulfide-based, and polymer-based. Polymer solid electrolytes have attracted attention due to advantages such as productivity and flexibility. As polymers that function as solid electrolytes in a state containing a solvent (semi-solid electrolytes in the solid state and gel electrolytes in the gel state may be referred to), polyvinylidene fluoride (hereinafter sometimes referred to as PVDF) and polyacrylonitrile (hereinafter sometimes referred to as PAN) are known. On the other hand, polymers that conduct ions without containing a solvent, such as polyethylene oxide (hereinafter sometimes referred to as PEO), are known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The polymer gel electrolyte disclosed in Patent Document 1, which uses PAN as a base polymer and adds a high-dielectric constant solvent, tends to have higher heat resistance than conventional LIBs. However, since it still uses a high-dielectric constant solvent, that is, an organic solvent, it has a risk of ignition.

[0007] In addition, Patent Document 2 discloses a battery that uses a polymer solid electrolyte film that does not add an organic solvent with PEO as a base polymer as a separator layer. Since this battery does not use an organic solvent, there is no risk of ignition or leakage caused by the electrolyte. On the other hand, PEO, which is the base polymer, has a melting point of 60 to 70°C and lacks heat resistance.

[0008] Therefore, in view of such problems, an object of the present invention is to provide a polymer solid electrolyte that exhibits ionic conductivity without adding an organic solvent and has high heat resistance.

Means for Solving the Problems

[0009] As a result of intensive studies to solve such problems, the present invention has found a polymer solid electrolyte that exhibits ionic conductivity without adding an organic solvent and is excellent in heat resistance, and has reached the present invention.

[0010] That is, in order to solve the above problems, the present invention has the following configuration. (1) A polymer solid electrolyte containing an alkali metal salt and polyether nitrile, wherein the polyether nitrile has a repeating unit represented by Chemical Formula (I) (Ar is an arylene group).

[0011]

Chemical formula

[0012] (In formula (I), Ar is a unit represented by formulas (a) to (k), and Ar is composed of one or more than two kinds of units.)

[0013] [Chemical formula]

[0014] (In formulas (a) to (k), R is any one of a linear organic group, a branched organic group, and a cyclic organic group having 1 to 6 carbon atoms, and may contain one or more selected from the group consisting of an oxygen atom, a nitrogen atom, and a sulfur atom. Note that R may be equal to or different from each other. a represents the number of substituents of R and is an integer of 0 to 4. X is a hydrogen atom or a methyl group.) (2) The polymer solid electrolyte according to (1), wherein the glass transition temperature of the polyether nitrile is 100°C or higher.) (3) A polymer solid electrolyte film containing the polymer solid electrolyte according to (1) or (2). (4) The polymer solid electrolyte film according to (3), wherein the Gurley permeability is 10,000 seconds / 100 cm 3 or more.) (5) A method for producing the polymer solid electrolyte film according to (3), comprising the steps of obtaining a solution by dissolving polyether nitrile and an alkali metal salt in an organic solvent, and volatilizing the organic solvent by drying the solution at 80°C or higher and 180°C or lower in this order.) (6) An electrode containing the polymer solid electrolyte according to (1) or (2) and an active material.) (7) A battery containing the polymer solid electrolyte according to (1) or (2). [Advantages of the Invention]

[0015] According to the present invention, it is possible to provide a polymer solid electrolyte that exhibits ionic conductivity without adding an organic solvent and is also excellent in heat resistance.) [Embodiments for Carrying Out the Invention]

[0016] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments described below.

[0017] (Polymer solid electrolyte) The polymer solid electrolyte of the present invention contains an alkali metal salt and polyether nitrile. The polymer solid electrolyte in the present invention refers to a substance that is in a solid state at room temperature and allows ions to move easily when an electric field is applied from the outside. In the present invention, a solid refers to a substance that retains its shape regardless of the shape of the container.

[0018] Further, unlike the separator film used in conventional LIBs, the polymer solid electrolyte allows alkali metal ions to move through the solid in the absence of an organic electrolyte solution. Therefore, in Gurley permeability measurement (JIS P8117:2009), for the separator film, the above Gurley permeability is 10000 seconds / 100 cm 3 When the above porosity is not sufficient, the separator film cannot be passed through by alkali metal ions and cannot be used as a separator, but the film of the polymer solid electrolyte has the above Gurley permeability of 10000 seconds / 100 cm 3 Even in the above case, alkali metal ions can pass through the solid of the polymer solid electrolyte and can be used as a separator.

[0019] From the viewpoints of ionic conductivity as an electrolyte for battery applications and charge-discharge performance of the battery, the ionic conductivity of the polymer electrolyte of the present invention is preferably 10 -8 S / cm or more, more preferably 10 -6 S / cm or more.

[0020] (Alkali metal salt) It is important that the polymer solid electrolyte of the present invention contains an alkali metal salt from the viewpoint of ionic conductivity. An alkali metal salt is a salt formed by ionic bonding between an alkali metal ion and a counter anion.

[0021] Examples of the alkali metal ions include lithium ions, sodium ions, potassium ions, magnesium ions, calcium ions and the like.

[0022] The alkali metal salt preferably includes lithium salts and sodium salts. Specifically, it is more preferable to include one or more selected from lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalato)borate (LiBOB), sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium bis(fluorosulfonyl)imide (NaFSI), and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI). From the viewpoint of high ion dissociation property, it is further preferable to include one or more obtained from LiTFSI and LiFSI.

[0023] A plurality of types of alkali metal salts may be mixed at an arbitrary ratio and used.

[0024] The content of the alkali metal salt is preferably such that the ratio of the number of moles of oxygen of the ether bond present in the alkali metal salt and the polyether nitrile is 1:100 or more and 200:100 or less. By being 1:100 or more, more preferably 10:100 or more, the ionic conductivity is excellent. Further, by being 200:100 or less, more preferably 100:100 or less, the processability and handleability are more excellent.

[0025] (Polyether nitrile) The polymer solid electrolyte of the present invention exhibits ionic conductivity by containing a specific polyether nitrile, and the battery using the polymer solid electrolyte of the present invention has high heat resistance.

[0026] Since the polyether nitrile has an oxygen atom in the ether bond and a nitrile group, an alkali metal salt can be ionized without adding an organic solvent. Further, since the oxygen atom in the ether bond and the nitrile group are included in the repeating unit of the polyether nitrile, the ionized alkali metal ions can move without adding an organic solvent. As a result, by including the polyether nitrile without adding an organic solvent, the polymer solid electrolyte of the present invention exhibits ionic conductivity.

[0027] The polyether nitrile has an arylene ether skeleton and high heat resistance. A polymer solid electrolyte using a polyether nitrile with high heat resistance inevitably has high heat resistance. As a result, the battery using the polymer solid electrolyte of the present invention has high heat resistance.

[0028] The polyether nitrile used in the present invention has a repeating unit represented by chemical formula (I).

[0029]

Chemical formula

[0030] (In chemical formula (I), Ar is a unit represented by formulas (a) to (k), and Ar is composed of one or more types of units.)

[0031]

Chemical formula

[0032] (In formulas (a) to (k), R is any of a linear organic group, a branched organic group, and a cyclic organic group having 1 to 6 carbon atoms, and may contain one or more selected from the group consisting of an oxygen atom, a nitrogen atom, and a sulfur atom. Note that R may be equal to or different from each other. a represents the number of substituents of R and is an integer from 0 to 4. X is a hydrogen atom or a methyl group.) The polyether nitrile used in the present invention preferably has a repeating unit represented by the above chemical formula (I) and a being 0 in all of the units represented by the above formulas (a) to (k).

[0033] Unlike the simple mixture of polyethylene oxide and polyacrylonitrile, the polyether nitrile contained in the polymer solid electrolyte of the present invention has a structure of the above chemical formula (I), which can ionize an alkali metal and exhibit ionic conductivity, and further shows high heat resistance.

[0034] The polyether nitrile used in the present invention is crystalline or amorphous.

[0035] The end groups of the polyether nitrile used in the present invention are a hydroxyl group, a metal salt of a hydroxyl group, a halogeno group, a linear organic group having 1 to 16 carbon atoms, a branched organic group having 3 to 16 carbon atoms, and a cyclic organic group having 3 to 16 carbon atoms. The end structure of the polyether nitrile used in the present invention can be evaluated by nuclear magnetic resonance (NMR) analysis.

[0036] The glass transition temperature of the polyether nitrile used in the present invention is preferably 100°C or higher, more preferably 130°C or higher, and still more preferably 150°C or higher. When the glass transition temperature of the polyether nitrile is at the above temperature or higher, the heat resistance of the battery using the polymer solid electrolyte of the present invention becomes high.

[0037] The method for producing the polyether nitrile used in the present invention is not particularly limited as long as it can synthesize a polyether nitrile having a repeating unit represented by the above chemical formula (I), and any production method can be adopted. For example, an aromatic compound (M1) substituted with two hydroxyl groups, one or more kinds, an aromatic compound (M2) having a benzonitrile skeleton substituted with two halogeno groups, and a mixture of a base are heated in an organic polar solvent to produce it.

[0038] Examples of the aromatic compound (M1) substituted with two hydroxyl groups include compounds represented by the formulas (a') to (k') corresponding to the formulas (a) to (k).

[0039] [Chemical formula]

[0040] In the above formulas (a') to (k'), R is any one of a linear organic group having 1 to 6 carbon atoms, a branched organic group having 3 to 6 carbon atoms, and a cyclic organic group having 3 to 6 carbon atoms, and may contain one or more oxygen atoms, nitrogen atoms, or sulfur atoms. a represents the number of substituents of R and is an integer from 0 to 4. When there are a plurality of Rs, they may be the same as or different from each other.

[0041] Examples of the aromatic compound (M2) having a benzonitrile skeleton substituted with two halogeno groups include the compound represented by the formula (l).

[0042] [Chemical formula]

[0043] In the formula (l), R is any one of a linear organic group having 1 to 6 carbon atoms, a branched organic group having 3 to 6 carbon atoms, and a cyclic organic group having 3 to 6 carbon atoms, and may contain one or more oxygen atoms, nitrogen atoms, or sulfur atoms. a represents the number of substituents of R and is an integer from 0 to 3. X1 and X2 are each independently a halogen atom and may be the same or different. When there are a plurality of Rs, they may be the same as or different from each other.

[0044] The polyether nitrile used in the present invention may have a random or block copolymer sequence, but is preferably random from the viewpoint of crystallinity.

[0045] For the purpose of adjusting the molecular weight during the production of the polyether nitrile used in the present invention, the following formulas (m) and (n) can be added.

[0046] [Chemical formula]

[0047] In formulas (m) and (n), Q is any one of a linear organic group having 1 to 10 carbon atoms, a branched organic group having 3 to 10 carbon atoms, and a cyclic organic group having 3 to 10 carbon atoms, and may contain one or more oxygen atoms, nitrogen atoms, or sulfur atoms. Note that Q may be equal to or different from each other. b represents the number of substituents of Q and is an integer from 0 to 5. Specifically, examples include phenol, 4-phenylphenol, 4-tert-butylphenol, 4-cumylphenol, 4-phenoxyphenol, 4-ethylphenol, 4-methoxyphenol, 4-tert-octylphenol, 1-naphthol, and 2-naphthol. Among them, from the viewpoint of manufacturability, 4-phenylphenol, 4-phenoxyphenol, 1-naphthol, and 2-naphthol are preferred.

[0048] The molecular weight calculated from the NMR of the polyether nitrile is preferably 5000 or more from the viewpoints of film-forming property and heat resistance.

[0049] (Method for producing a polymer solid electrolyte and its film) The polymer solid electrolyte and the polymer solid electrolyte film of the present invention exhibit performance as long as they have the configuration of the present invention regardless of the production method. For example, the solution method, melt extrusion method, calender method, or compression molding method is exemplified as the production method. Among the above production methods, from the viewpoint of processability, it is preferable to produce by the solution method or the melt extrusion method. Further, from the viewpoint of the dispersibility of the alkali metal salt and the polyether nitrile, and in the case of a film, from the viewpoint of thinning the film, it is more preferable to produce by the solution method.

[0050] Examples of the melt extrusion method include a method in which an alkali metal salt and a polyether nitrile are supplied to a twin-screw extruder and melt-extruded. Particularly in the case of a film, a method is exemplified in which an alkali metal salt and a polyether nitrile are supplied to a twin-screw extruder equipped with a T-die at the tip, and the melt-extruded film is cast onto a casting drum to continuously obtain a film-like material. The processing temperature in the twin-screw extruder is preferably 180°C or higher and 350°C or lower. Also, the casting drum may be cooled to an arbitrary temperature using a chiller.

[0051] Examples of the solution method include a method (hereinafter sometimes referred to as solution film formation) having, in this order, a step of obtaining a solution in which a polyether nitrile and an alkali metal salt are dissolved in an organic solvent, and a step of drying the solution at 80°C or higher and 180°C or lower to volatilize the organic solvent.

[0052] The organic solvent is not particularly limited as long as it can dissolve both the alkali metal salt and the polyether nitrile. Examples thereof include aprotic polar solvents such as N-methyl-2-pyrrolidone, dichloromethane, dichloroethane, N,N-dimethylacetamide, tetrahydrofuran, γ-butyrolactone, ethyl acetate, acetonitrile, dimethylformamide, and dimethyl sulfoxide. Among these, N-methyl-2-pyrrolidone is particularly preferred from the viewpoints of simplicity of the drying process, stability and toxicity of the solvent, etc. In the step of drying the solution to volatilize the organic solvent, when obtaining a polymer solid electrolyte film, it is preferable to dry the solution after uniformly casting or coating it.

[0053] The casting or coating of the solution in which the polyether nitrile and the alkali metal salt are dissolved may be performed on a support. The support may be directly coated using a positive electrode or a negative electrode. Alternatively, it may be cast or coated on another substrate and then dried, and this may be separated to obtain a polymer solid electrolyte film.

[0054] The material of the substrate is not particularly limited, and examples thereof include stainless steel, glass, and resins such as polyethylene terephthalate (PET).

[0055] Examples of the casting or coating of the solution include methods such as solvent casting, spin coating, doctor blade coating, dip coating, die coating, spray coating, roll coating, flow coating, bar coating, or knife coating.

[0056] The viscosity of the solution may be adjusted depending on the casting or coating method. The viscosity of the solution is preferably a value measured at 30 °C and 10 rpm using a B-type viscometer and is 1 to 800 Pa·s. More preferably, it is 10 to 600 Pa·s. If the solution viscosity is less than 1 Pa·s, the solution may flow excessively and not reach the desired film thickness. If the solution viscosity exceeds 800 Pa·s, casting or coating may become difficult.

[0057] After casting or coating the solution, drying is performed to volatilize the organic solvent. The drying temperature is preferably equal to or lower than the glass transition temperature of polyether nitrile, preferably 180 °C or lower, and more preferably 160 °C or lower. The lower limit temperature is preferably 80 °C or higher from the viewpoint of the efficiency of volatilizing the organic solvent.

[0058] The method of drying is not particularly limited, and examples thereof include hot air drying and vacuum drying.

[0059] The polymer solid electrolyte film of the present invention may be annealed or stretched after being formed into a film shape.

[0060] From the perspective of reducing resistance, the polymer solid electrolyte film of the present invention preferably has a thickness of 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. Also, from the perspectives of preventing short circuits and ease of handling when used in a battery, it preferably has a thickness of 0.1 μm or more, and more preferably 0.5 μm or more.

[0061] (Electrode and its manufacturing method) From the perspective of excellent ion conductivity, the electrode of the present invention contains the polymer solid electrolyte and the active material of the present invention. In addition to the polymer solid electrolyte and the active material, the electrode preferably further contains one or more selected from conductive materials and binders from the perspectives of conductivity and mechanical strength. Also, the electrode is a positive electrode or a negative electrode.

[0062] When the electrode is a positive electrode, examples of the positive electrode active material include oxides described as LiAl x Co y Ni z Mn w O2 where x + y + z + w = 1, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 ≤ w ≤ 1, and LiFePO4, LiMn x Fe 1-x O4, etc.

[0063] When the electrode is a negative electrode, examples of the negative electrode active material include graphite, hard carbon, Li4Ti5O 12 , Si(SiO x ), etc.

[0064] Without being limited as long as the effects of the present invention are not impaired, the electrode in the present invention can be manufactured as follows. First, a solution in which an alkali metal salt and a polyether nitrile are dissolved in an organic solvent is obtained. An active material is added to and mixed with the solution to obtain a slurry of the active material. The slurry is applied to a conductive substrate and dried to obtain an electrode containing a polymer solid electrolyte.

[0065] (Battery and its manufacturing method) The battery of the present invention includes the polymer solid electrolyte of the present invention. The battery of the present invention consists of a positive electrode, a negative electrode, and a separator layer, and at least one of the positive electrode, the negative electrode, and the separator layer includes the polymer solid electrolyte of the present invention. The positive electrode included in the battery of the present invention can use the electrode of the present invention. As the negative electrode included in the battery of the present invention, the electrode of the present invention, Li metal, an alloy of In or Sn and Li, etc. can be used. For the separator layer included in the battery of the present invention, it is preferable to use the polymer solid electrolyte film of the present invention. Although not limited as long as the effects of the present invention are not impaired, the battery in the present invention can be manufactured as follows. First, a polymer solid electrolyte film is produced by the method for producing the polymer solid electrolyte film. Also, a positive electrode and a negative electrode are produced by the method for producing the electrode. The positive electrode, the negative electrode, and the polymer solid electrolyte film are laminated. At this time, in order to ensure the contact between the positive electrode and the polymer solid electrolyte film and between the negative electrode and the polymer solid electrolyte film, heat pressure bonding may be performed. The laminate of the positive electrode, the polymer solid electrolyte film, and the negative electrode obtained as described above is molded into a coin cell, a laminate cell, a cylindrical cell, a square cell, etc. to obtain the battery of the present invention.

Examples

[0066] Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited only to these.

[0067] [Measurement method] (1) Structure confirmation When the polyether nitrile is composed of two or more repeating units, the molar ratio of the two or more repeating units was evaluated using nuclear magnetic resonance spectroscopy (NMR). NMR was performed in a mixed solvent of pentafluorophenol / deuterated chloroform = 5 / 3 (volume ratio) using JNM-ECZ-500R manufactured by JEOL Ltd. 1 1H-NMR measurement was performed, and the molar ratio of two or more repeating units constituting the polyether nitrile was calculated from the ratio of the integral values of the obtained spectra.

[0068] (2) Measurement of glass transition temperature, melting point, heat of fusion, and cold crystallization temperature The crystallinity determination, glass transition temperature, melting point, heat of fusion, and cold crystallization temperature of the polyether nitrile were determined by differential scanning calorimetry (DSC) measurement. The DSC measurement was performed using a Q20 manufactured by TA Instruments. Using a cooled press film (3 to 10 mg), the temperature was raised from 50°C to 400°C at a rate of 10°C / min, and based on the results, it was determined whether the polyether nitrile was crystalline or amorphous. In the case of crystallinity, the glass transition temperature, melting point, heat of fusion, and cold crystallization temperature were calculated. In the case of amorphousness, the glass transition temperature was calculated. The press film was prepared using a tabletop test press SA303 manufactured by Tester Sangyo Co., Ltd.

[0069] (3) Evaluation of heat resistance The heat resistance of the polymer solid electrolyte depends on the heat resistance of the polymer contained in the polymer solid electrolyte. That is, when the heat resistance of the polyether nitrile is excellent, inevitably, the heat resistance of the polymer solid electrolyte of the present invention will be excellent. Therefore, for the evaluation of the heat resistance of the polymer solid electrolyte, in the DSC measurement in (2) above, those with a glass transition temperature of the polymer less than 100°C were given a D evaluation, those with a glass transition temperature of 100°C or more and less than 130°C were given a C evaluation, those with a glass transition temperature of 130°C or more and less than 150°C were given a B evaluation, and those with a glass transition temperature of 150°C or more were given an A evaluation. In order to obtain the effects of the present invention, the evaluation of heat resistance needs to be C evaluation or higher, B evaluation or higher is preferable, and A evaluation or higher is more preferable.

[0070] (4) Thickness The thickness of the polymer solid electrolyte was measured with a constant pressure thickness measuring instrument in accordance with JIS K6250 (2019).

[0071] (5) Gurley air permeability measurement Using a Gurley densometer (manufactured by Toyo Seiki Seisakusho, G-B3C), the measurement was performed in accordance with the method specified in JIS-P8117 (2009). A sample of the polymer solid electrolyte film had a diameter of 28.6 mm and an area of 642 mm 2Fasten it to the circular hole, and use the inner cylinder (inner cylinder mass: 567 g) to allow the air inside the cylinder to pass from the test circular hole part to the outside of the cylinder. The Gurley permeability was determined by measuring the time it takes for 100 ml of air to pass through. When the Gurley permeability exceeds 10,000 seconds / 100 cm 3 it is not measured any further, and the measurement result is expressed as 10,000 seconds / 100 cm 3 or more. The Gurley permeability of the polymer solid electrolyte must be 10,000 seconds / 100 cm 3 or more.

[0072] (6) Ionic conductivity The ionic conductivity of the polymer solid electrolyte was determined by alternating current impedance measurement. The polymer solid electrolyte was set in a pressure holder (LN-Z2-HF-PH series manufactured by Toyo Technica Co., Ltd.), and the thickness of the polymer solid electrolyte was measured. Then, using an impedance measurement device (4990EDMS-120K manufactured by Toyo Technica Co., Ltd.), an alternating current voltage of 100 Hz to 100 MHz was applied at 25°C, and the impedance was measured by the complex impedance method to obtain a Nyquist plot. Then, the temperature was raised, and the impedance was measured in the same manner at each temperature in the order of 40°C, 60°C, and 80°C to obtain a Nyquist plot. From the obtained Nyquist plot, the resistance value (R) was read, and together with the measured thickness (D) and the sample area (S) in contact with the measurement electrode, the ionic conductivity (σ) was calculated using the following formula (1).

[0073]

Equation

[0074] Since the sample area was punched out to a diameter of 10 mm, it was calculated as 78.5 mm 2 as calculated.

[0075] Note that the ionic conductivity was expressed with E as the power of 10. That is, for example, "1.0E-6" represents 1.0×10 -6 as represented.

[0076] For the evaluation of ionic conductivity, when measuring the ionic conductivity at room temperature, 40 °C, 60 °C, and 80 °C, those with an ionic conductivity of less than 1.0E-6 S / cm at all four temperatures were evaluated as B, and those showing 1.0E-6 S / cm or more at any one temperature were evaluated as A. In order to obtain the effect of the present invention, the ionic conductivity needs to be evaluated as A.

[0077] [Constituent components] (Polyether nitrile 1) In Chemical Formula (I), a polyether nitrile composed of only one type of unit (Chemical Formula (II)) in which Ar is Formula (a) and the number of substituents of R in Formula (a) is 0 was designated as Polyether Nitrile 1.

[0078] [Chemical formula]

[0079] (Polyether nitrile 2) In Chemical Formula (I), a polyether nitrile composed of two types of units, a unit (Chemical Formula (II)) in which Ar is Formula (a) and the number of substituents of R in Formula (a) is 0, and a unit (Chemical Formula (III)) in which Ar is Formula (c) and the number of substituents of R in Formula (c) is 0, and the molar ratio of the two types of units is 1:1 was designated as Polyether Nitrile 2.

[0080] [Chemical formula]

[0081] (Polyether nitrile 3) In Chemical Formula (I), a polyether nitrile composed of two types of units, a unit (Chemical Formula (III)) in which Ar is Formula (c) and the number of substituents of R in Formula (c) is 0, and a unit (Chemical Formula IV) in which Ar is Formula (d) and the number of substituents of R in Formula (d) is 0, and the molar ratio of the two types of units is 1:1 was designated as Polyether Nitrile 3.

[0082] [Chemical formula]

[0083] (Alkali metal salt) Lithium bis(trifluoromethanesulfonyl)imide (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the alkali metal salt.

[0084] [Examples 1 - 2] Polyether nitrile and an alkali metal salt were weighed in the combinations and mass ratios shown in Table 1, and dissolved in N-methyl-2-pyrrolidone (NMP) (manufactured by Fujifilm Wako Pure Chemical Corporation) so that the polyether nitrile concentration became 15% by mass. The NMP solution of the polyether nitrile and the alkali metal salt was applied onto a glass substrate and flattened using an applicator set to a clearance of 160 μm. The applied solution was dried in an oven at 110°C for 15 minutes and then peeled off from the glass substrate. Finally, it was vacuum dried at 100°C for 12 hours to obtain a film of the polymer solid electrolyte. The films using the polymer solid electrolytes of Examples 1 - 2 showed ionic conductivities of 5.1E-6 in Example 1 and 1.5E-5 in Example 2 at 80°C without adding a solvent, and the evaluations of the ionic conductivities of Examples 1 - 2 were both A. Also, the glass transition temperatures of both polyether nitrile 1 and polyether nitrile 2 were 180°C, and the heat resistance evaluation was an A evaluation. Also, the Gurley air permeability of the films using the polymer solid electrolytes of Examples 1 - 2 was 10,000 seconds / 100 cm 3 as above.

[0085] [Example 3] A polyether nitrile and an alkali metal salt were weighed in the combination described in Table 1 and in a mass ratio, and dissolved in N-methyl-2-pyrrolidone (NMP) (manufactured by Fujifilm Wako Pure Chemical Corporation) so that the polyether nitrile concentration became 13% by mass. Thereafter, a film of the polymer solid electrolyte was obtained in the same manner as in Examples 1 and 2. The film using the polymer solid electrolyte of Example 3 showed an ionic conductivity of 1.8E-5 at 80 °C without adding a solvent, and the evaluation of the ionic conductivity of Example 3 was A. Also, the glass transition temperature of polyether nitrile 3 was 155 °C, and the heat resistance evaluation was an A evaluation. Also, the Gurley air permeability of the film using the polymer solid electrolyte of Example 3 was 10,000 seconds / 100 cm 3 or less.

[0086] [Comparative Example 1] Only polyether nitrile was dissolved in NMP so that the concentration became 15% by mass, and thereafter, a polyether nitrile film formed in the same manner as in Examples 1 to 2 was used as Comparative Example 1. The heat resistance of Comparative Example 1 was evaluated as A, but the evaluation of the ionic conductivity was B, which was inferior. Also, the Gurley air permeability of the film using the polymer solid electrolyte of Comparative Example 1 was 10,000 seconds / 100 cm 3 or less.

[0087] [Comparative Example 2] Polyethylene oxide (number average molecular weight 5,000,000) (manufactured by Fujifilm Wako Pure Chemical Corporation) and an alkali metal salt were weighed in the mass ratio described in Table 1 and dissolved in acetonitrile so that the polyethylene oxide concentration became 15% by mass. The acetonitrile solution of the polyethylene oxide and the alkali metal salt was applied in the same manner as in Examples 1 to 2, and after performing hot air drying at 40 °C for 4 hours, vacuum drying was performed at 50 °C for 48 hours to obtain a film of the polymer solid electrolyte using polyethylene oxide. The film using the polyethylene oxide polymer solid electrolyte of Comparative Example 2 had an A evaluation for the ionic conductivity evaluation without adding a solvent, but a D evaluation for the heat resistance evaluation.

[0088] [Comparative Example 3] Polyacrylonitrile (number average molecular weight: 150,000, manufactured by Sigma-Aldrich) and an alkali metal salt were weighed at the mass ratios shown in Table 1, and dissolved in NMP so that the polyacrylonitrile concentration became 10% by mass. The NMP solution of the polyacrylonitrile and the alkali metal salt was applied and dried by the same means as in Examples 1 to 2 to obtain a film of a polymer solid electrolyte using polyacrylonitrile. The film using the polyacrylonitrile polymer solid electrolyte of Comparative Example 3 had an ion conductivity evaluation of B, and the heat resistance of the polymer was evaluated as C.

[0089] Table 1 shows the compositions and performances of the films of the polymer solid electrolytes of Examples 1 to 2 and Comparative Examples 1 to 3.

[0090]

Table 1

Claims

1. A polymer solid electrolyte comprising an alkali metal salt and a polyether nitrile, The polyethernitrile has a repeating unit represented by chemical formula (I) (Ar is an arylene group). 【Chemistry 1】 (In chemical formula (I), Ar is a unit represented by formulas (a) to (k), and Ar is composed of one or more types of units.) 【Chemistry 2】 (In formulas (a) to (k), R is any one of a linear organic group, a branched organic group, and a cyclic organic group having 1 to 6 carbon atoms, and may contain one or more atoms selected from the group consisting of an oxygen atom, a nitrogen atom, and a sulfur atom. R may be the same or different from each other. a represents the number of substituents on R and is an integer of 0 to 4. X is a hydrogen atom or a methyl group.)

2. 2. The polymer solid electrolyte according to claim 1, wherein the polyethernitrile has a glass transition temperature of 100° C. or higher.

3. A polymer solid electrolyte film comprising the polymer solid electrolyte according to claim 1 or 2.

4. 4. The polymer solid electrolyte membrane according to claim 3, having a Gurley air permeability of 10,000 sec / 100 cm ３ That is all about the polymer solid electrolyte film.

5. 4. A method for producing a polymer solid electrolyte membrane according to claim 3, comprising the steps of: obtaining a solution by dissolving a polyether nitrile and an alkali metal salt in an organic solvent; and drying the solution at 80° C. or higher and 180° C. or lower to volatilize the organic solvent, in this order.

6. An electrode comprising the polymer solid electrolyte according to claim 1 or 2 and an active material.

7. A battery comprising the polymer solid electrolyte according to claim 1 or 2.

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