Polymer electrolyte and secondary battery

Abstract

Provided is a polymer electrolyte which is not susceptible to any decrease in strength even in a high-temperature range, and which has high ionic conductivity at room temperature and lower temperatures even without relying on a liquid electrolyte. The polymer electrolyte contains a polymer having a specific polyether structure having a free terminal, a cross-linked structure produced using a specific polyether, and a specific ammonium cationic group, the polymer electrolyte further contains a lithium salt, and the volume swelling ratio of the polymer electrolyte as determined by a methyl ethyl ketone impregnation method is 40-120%.

Description

Technical Field

[0001] The present disclosure relates to a polymer electrolyte and a secondary battery. Background Art

[0002] In recent years, with the development of portable devices such as tablet terminals and smart phones and electric vehicles, the demand for secondary batteries as their power sources has increased. Generally, secondary batteries are composed of electrodes (positive and negative electrodes) and electrolytes, and are charged and discharged by the migration of ions between the electrodes through the electrolyte. The application of such secondary batteries ranges from small devices such as mobile phones to large devices such as electric vehicles. Therefore, high safety and further improvement of performance are required.

[0003] In order to further improve the safety of secondary batteries, solid-state secondary batteries are being developed in which a solid main electrolyte is used instead of a conventional flammable electrolyte. Sulfide-based, oxide-based, and polymer-based materials are widely studied as solid electrolytes.

[0004] In order to improve the charge and discharge characteristics of secondary batteries, it is generally important to increase the interface between the active material in the electrode and the electrolyte. Here, the active material is a substance that participates in the reaction that generates electricity. Although sulfide-based and oxide-based solid electrolytes have excellent ionic conductivity, it is difficult to increase the interface with the active material and the impact resistance may be insufficient. Therefore, the use of gel electrolytes in which the electrolyte is combined with a polymer has been proposed.

[0005] Patent Document 1 describes a gel electrolyte containing a polyether and an ionic liquid. Patent Document 2 describes a gel electrolyte whose affinity for the electrolyte is improved by incorporating a quaternary ammonium base into the main chain. In addition, Patent Document 3 discloses a polymer electrolyte containing a linear polymer and an ionic liquid.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: JP-A-2017-090677

[0009] Patent Document 2: WO 2004 / 027789

[0010] Patent Document 3: JP-A-2007-280912 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] In recent years, there has been a demand for lithium-ion secondary batteries with improved charge / discharge characteristics in addition to high safety. When polymer gels, such as those disclosed in Patent Documents 1 and 2, are used as electrolytes, or when polymer electrolytes using linear polymers, such as those disclosed in Patent Document 3, are used, it is believed that the strength at high temperatures is insufficient and that strong impacts can cause short circuits. Furthermore, when the liquid electrolyte is removed to prevent short circuits, ionic conductivity may decrease.

[0013] At least one aspect of the present disclosure is to provide a polymer electrolyte having high ion conductivity. In addition, at least one aspect of the present disclosure is to provide a secondary battery that exhibits excellent strength and excellent battery performance even under high temperature environments.

[0014] Solutions for solving problems

[0015] At least one aspect of the present disclosure provides a polymer electrolyte,

[0016] The polymer electrolyte comprises a polymer having:

[0017] The structure represented by the following formula (1);

[0018] At least one structure selected from the group consisting of a structure represented by the following formula (2) and a structure represented by the following formula (3); and

[0019] The structure represented by the following formula (4)

[0020] The polymer electrolyte further comprises a lithium salt, and

[0021] The volume swelling rate of the polymer electrolyte measured by the methyl ethyl ketone immersion method is 40% to 120%.

[0022] [Chemical Formula 1]

[0023]

[0024] (In formula (1), R 1 Represents a hydrogen atom or a methyl group. 2 represents a linear or branched alkylene group having 1 to 6 carbon atoms. 3 It represents an alkyl group having 1 to 6 carbon atoms.

[0025] In formula (2), R 4 Each independently represents a hydrogen atom or a methyl group. 5 and R 6 Each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms.

[0026] In formula (3), R 7Each independently represents a hydrogen atom or a methyl group. 8 、R 9 and R 10 Each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms. 11 It represents a trivalent organic group having 1 to 6 carbon atoms.

[0027] A1, B1, D1, D2 and D3 in formulae (1) to (3) are each independently a linking group having at least an ethylene oxide structure represented by (-CH2CH2-O-).

[0028] [Chemical Formula 2]

[0029]

[0030] (In formula (4), R 12 Represents a hydrogen atom or a methyl group. 13 Represents a divalent linking group. 14 、R 15 and R 16 Each independently represents an alkyl group having 1 to 8 carbon atoms. - represents an anion. ).

[0031] In addition, at least one aspect of the present disclosure provides a secondary battery comprising a positive electrode, a bulk electrolyte, and a negative electrode, wherein

[0032] At least one selected from the group consisting of a positive electrode, a main electrolyte, and a negative electrode includes the above-mentioned polymer electrolyte.

[0033] Effects of the Invention

[0034] According to at least one aspect of the present disclosure, a polymer electrolyte having high ion conductivity can be obtained. In addition, according to at least one aspect of the present disclosure, a secondary battery having excellent strength and excellent battery performance even under high temperature environments can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic cross-sectional view of a secondary battery using the polymer electrolyte of the present disclosure as a main electrolyte.

[0036] Figure 2 Schematic cross-sectional view of a secondary battery using the polymer electrolyte disclosed herein as a positive electrode active material binder.

[0037] Figure 3 Schematic cross-sectional view of a secondary battery using the polymer electrolyte disclosed herein as a positive electrode active material binder, a main electrolyte, and a negative electrode active material binder. DETAILED DESCRIPTION

[0038] In the present disclosure, unless otherwise specified, the expression "XX or more and YY or "XX to YY (XX to YY)" indicating a numerical range means a numerical range including the lower limit and the upper limit as endpoints. In addition, when describing a numerical range in stages, the upper limit and the lower limit of each numerical range can be freely combined. In addition, in the present disclosure, for example, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any one of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, and a combination of XX, YY, and ZZ.

[0039] To achieve the above objectives, the present inventors have conducted intensive research. First, the present inventors discovered that in dry polymer systems where promotion of lithium ion migration by liquid electrolytes cannot be expected, ionic conductivity can be improved by using a polyether acrylic resin having a specific three-dimensional crosslinked morphology.

[0040] As a result of further research, the present inventors discovered that high ionic conductivity can be maintained even at low temperatures only when the molecule contains an anion and a cationic group having a nitrogen-containing heterocyclic structure. This discovery enabled the present inventors to obtain the aforementioned polymer electrolyte. In other words, the polymer electrolyte disclosed herein satisfies the following conditions.

[0041] - The three-dimensional cross-linked structure of the polymer has many terminal free chains that are not bonded to the polymer chain at one end and has a very low cross-linking density.

[0042] - The three-dimensional cross-linked structure of the polymer has anions and cationic groups having a nitrogen-containing aromatic structure.

[0043] The present inventors speculate as to why the polymer electrolytes disclosed herein exhibit unexpectedly high ionic conductivity without relying on a liquid electrolyte. In dry polymer systems where lithium ion stabilization by a liquid electrolyte is undesirable, lithium ions migrate between polymer chains undergoing molecular motion. Therefore, polymer systems that have been three-dimensionally cross-linked to suppress the risk of short circuits due to membrane deformation at high temperatures are more susceptible to steric hindrance than liquid systems.

[0044] The polymer used in the present disclosure has a three-dimensional cross-linked structure (the structures of formulas (2) and (3)) and is not easily deformed even at high temperatures. At the same time, the structure has many free-terminal chains (the structure of formula (1)) at one end of which are not bonded to another polymer chain. This is obviously the reason why the polymer does not form a dense network structure and is less likely to hinder the migration of lithium ions while maintaining strength.

[0045] Furthermore, the ammonium cation structure and anion (structure of formula (4)) bonded to the polymer structure reduce the polarity difference between the lithium salt as the supporting electrolyte contained therein and the polymer, do not cause precipitation of the lithium salt, and increase its soluble amount.

[0046] Furthermore, it is considered that the ammonium cation structure bonded in the above-mentioned polymer structure suppresses three-dimensional regularity and reduces the crystallinity of the polymer, thereby suppressing a decrease in ion conductivity at low temperatures.

[0047] The fact that the three-dimensional cross-linked structure of the polymer has many free end chains that are not bonded to the polymer chain at one end and has a very low cross-linking density is clearly reflected in the volume swelling rate of the polymer electrolyte determined by the methyl ethyl ketone immersion method. Specifically, the volume swelling rate of the polymer electrolyte determined using methyl ethyl ketone (MEK) is 40% to 120%.

[0048] The volume swelling ratio represents the ratio of the volume of a three-dimensional cross-linked polymer before and after it is immersed in a specific solvent and the swelling caused by the solvent reaches saturation. The volume swelling ratio is calculated using the following formula, where the volume of the test sample is calculated from its weight in air and its weight in water. The specific measurement method is described below.

[0049] Volume swelling ratio (%) = (volume after immersion in solvent and saturation swelling) / (volume before immersion in solvent) × 100

[0050] A polymer electrolyte volume swelling ratio of less than 40% is believed to indicate the presence of few free end chains (structure of formula (1)) and a large amount of three-dimensional crosslinked structure. As a result, ionic conductivity tends to be low, and the rate characteristics of the secondary battery tend to be reduced. Meanwhile, a polymer electrolyte volume swelling ratio of greater than 120% indicates a lack of three-dimensional crosslinked structure, which tends to lead to reduced strength, such as reduced impact resistance at high temperatures.

[0051] The volume swelling ratio of the polymer electrolyte is preferably 60% to 110%, more preferably 70% to 105%.

[0052] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The components, materials, shapes and relative positions described in these embodiments do not limit the scope of the present disclosure.

[0053] (1) Implementation of secondary battery

[0054] The secondary battery comprises a positive electrode, a main electrolyte and a negative electrode, and at least one of the positive electrode, the main electrolyte and the negative electrode comprises the polymer electrolyte of the present disclosure. For example, the main electrolyte is a polymer electrolyte.

[0055] An example of a secondary battery using the polymer electrolyte of the present disclosure is shown in Figures 1 to 3middle. Figure 1 The secondary battery 1 shown is an example of a schematic configuration of a secondary battery using a polymer electrolyte as a main electrolyte 7. A positive electrode active material 3 provided on a positive electrode current collector 2 is fixed by a positive electrode active material binder 4 to form a positive electrode 6. The positive electrode 6 may include a conductive auxiliary material 5.

[0056] The negative electrode active material 8 provided on the negative electrode current collector 9 forms the negative electrode 10. Figure 1 In FIG, the negative electrode active material represents metal lithium, indium, etc. The main electrolyte 7 is provided between the positive electrode 6 and the negative electrode 10 .

[0057] Figure 2 The secondary battery 1 shown represents an example of a schematic configuration of a secondary battery using a polymer electrolyte as the positive electrode active material binder 4. Figure 2 In the embodiment shown, the positive electrode 6 includes a polymer electrolyte. For example, the positive electrode 6 includes a positive electrode active material 3 and a positive electrode active material binder 4 that fixes the positive electrode active material, and the positive electrode active material binder 4 is a polymer electrolyte of the present disclosure. Figure 2 In the structure shown, the main electrolyte 7 is an oxide-based or sulfide-based inorganic solid electrolyte. Figure 1 The same features as in .

[0058] Figure 3 The secondary battery 1 shown represents an example of a schematic configuration of a secondary battery using a polymer electrolyte as the positive electrode active material binder 4, the main electrolyte 7, and the negative electrode active material binder 11. Figure 3 In the embodiment shown, the positive electrode, the main electrolyte, and the negative electrode contain a polymer electrolyte. That is, the positive electrode 6 has a positive electrode active material 3 and a positive electrode active material binder 4 that fixes the positive electrode active material, and the positive electrode active material binder 4 is a polymer electrolyte of the present disclosure. In addition, the main electrolyte 7 is a polymer electrolyte of the present disclosure. In addition, the negative electrode 10 has a negative electrode active material 8 and a negative electrode active material binder 11 that fixes the negative electrode active material 8, and the negative electrode active material binder 11 is a polymer electrolyte of the present disclosure. Figure 3 In the structure shown, the negative electrode active material 8 is a carbon material such as graphite. Figure 1 The same features as in .

[0059] In order to more effectively achieve the effects of the present disclosure, Figure 1 and Figure 3 As shown, the main electrolyte 7 is preferably a polymer electrolyte that permeates the positive electrode active material 3 and the negative electrode active material 8 and increases the contact area.

[0060] (Method for manufacturing solid-state secondary battery)

[0061] The solid-state secondary battery can be manufactured by a known battery manufacturing method such as a stacked battery type, a button battery type, or a pressurized battery type. Hereinafter, the stacked battery type will be described as an example.

[0062] A laminate in which a positive electrode, a main electrolyte and a negative electrode are arranged between a positive electrode collector and a negative electrode collector is obtained. The electrode tabs are welded to the positive electrode and the negative electrode collector. The laminate in which the positive electrode collector, the positive electrode, the main electrolyte, the negative electrode and the negative electrode collector are stacked in sequence is packaged in an aluminum laminate film and sealed while reducing pressure by using a vacuum packaging machine. The ends of the electrode tabs are exposed to the outside of the laminate film, and the tabs and the aluminum laminate film are sealed in a state in which they are joined by hot pressing. After sealing, pressure can be applied using an isostatic pressing device or the like as needed. The main electrolyte can be a solid electrolyte or a polymer electrolyte, but both can be used in the laminate. In addition to the above-mentioned laminate, other layers such as elastic materials and resin materials can be stacked inside the aluminum laminate film for the purpose of improving strength and forming. A bipolar type in which multiple laminates are stacked can also be used.

[0063] (Positive electrode current collector)

[0064] Examples of the positive electrode current collector include metal foil. Examples of metals include aluminum, stainless steel, copper, silver, gold, platinum, nickel, and palladium. The metals may be used alone or in combination of two or more.

[0065] (Positive electrode active material)

[0066] The positive electrode active material can be selected from those commonly used in secondary batteries such as lithium ion secondary batteries. Examples thereof include (CF) m 、(C2F) m , MnO2, TiS2, MoS2, FeS2, Li xA CoO2、Li xA NiO2、Li xA MnO2、Li xA Co y Ni 1-y O2、Li xA Co y M 1-y O z 、Li xA Ni 1-y M y O z 、Li xB Mn2O4、Li xB Mn 2-y M yO4 (in the above formulas, m is at least one selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb and B. xA = 0 to 1.2, xB = 0 to 2.0, y = 0 to 0.9, z = 2.0 to 2.3), vanadium oxide and its lithium compounds, niobium oxide and its lithium compounds, conjugated polymers using organic conductive substances, olivine compounds, etc.

[0067] The xA and xB values in the above composition formula are values before the start of charge and discharge, and increase or decrease with charge and discharge. The positive electrode active material can be used alone or in combination of two or more.

[0068] (Conductive auxiliary materials)

[0069] The conductive auxiliary material can be selected from, for example, those commonly used in secondary batteries such as lithium-ion secondary batteries. Examples include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black, conductive fibers such as carbon fibers and metal fibers, metal powders such as aluminum powder, conductive whiskers such as zinc oxide whiskers and potassium titanate whiskers, conductive metal oxides such as titanium oxide, and organic conductive substances such as phenylene derivatives. The conductive auxiliary material can be used alone or in combination of two or more.

[0070] (Active material binder)

[0071] The active material binder can be selected from those commonly used in secondary batteries such as lithium ion secondary batteries. Examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyethylene, polypropylene, aromatic polyamide resins, polyamides, polyimides, polyamideimides, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinyl pyrrolidone, polyether, polyether sulfone, hexafluoropolypropylene, styrene butadiene rubber, and carboxymethyl cellulose.

[0072] The polymer electrolyte disclosed herein can be used as a main electrolyte, a positive electrode active material binder, a negative electrode active material binder, or as a main electrolyte, a positive electrode active material binder, and a negative electrode active material binder.

[0073] In other words, the secondary battery preferably satisfies at least one of the following (i) to (iii).

[0074] (i) The positive electrode 6 includes a positive electrode active material 3 and a positive electrode active material binder 4 for fixing the positive electrode active material. The positive electrode active material binder 4 is the polymer electrolyte disclosed herein.

[0075] (ii) The main electrolyte 7 is the polymer electrolyte of the present disclosure.

[0076] (iii) The negative electrode 10 has a negative electrode active material 8 and a negative electrode active material binder 11 that fixes the negative electrode active material 8. The negative electrode active material binder 11 is the polymer electrolyte of the present disclosure.

[0077] Particularly preferably, the polymer electrolyte of the present disclosure is used as the positive electrode active material binder because, in this case, lithium ions can easily reach the deep part from the surface of the positive electrode 6. One kind of active material binder can be used alone or two or more kinds can be used in combination.

[0078] The positive electrode 6 can be manufactured, for example, by pressing the positive electrode mixture onto the surface of the positive electrode current collector 2, or by coating and drying the positive electrode mixture slurry and further rolling it as needed to form the positive electrode 6. It can also be prepared by kneading the positive electrode active material, the conductive auxiliary material, and the positive electrode active material binder. The positive electrode mixture slurry can also be prepared, for example, by dissolving or dispersing the positive electrode active material, the conductive auxiliary material, and the active material binder in a medium such as dehydrated N-methyl-2-pyrrolidone, acetonitrile, methyl ethyl ketone, or ethylene glycol ether.

[0079] (Negative electrode current collector)

[0080] Examples of the negative electrode current collector include metal foils. Examples of the metal include aluminum, stainless steel, copper, silver, gold, platinum, nickel, and palladium. One kind of metal can be used alone or two or more kinds can be used in combination.

[0081] (Negative electrode active material)

[0082] Examples of the negative electrode active material include metals, metal fibers, carbon materials, oxides, nitrides, silicon, silicon compounds, tin, tin compounds, and various alloy materials. Among them, from the viewpoint of capacity density, metals, oxides, carbon materials, silicon, silicon compounds, tin, and tin compounds are preferred.

[0083] Examples of the metal include metallic Li and In-Li, and examples of the oxide include Li4Ti5O 12 (LTO: lithium titanate). Examples of the carbon material include various natural graphites, cokes, carbon during the graphitization process, carbon fibers, spherical carbon, various artificial graphites, and amorphous carbon. Examples of the silicon compound include silicon-containing alloys, silicon-containing inorganic compounds, silicon-containing organic compounds, and solid solutions. Examples of the tin compound include SnO B (0 < B < 2), SnO2, SnSiO3, Ni2Sn4, and Mg2Sn.

[0084] The negative electrode material may also contain a conductive auxiliary material. Examples of conductive auxiliary materials include graphites such as natural graphite and artificial graphite, and carbon blacks such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black. When a polymer electrolyte is used as the main electrolyte, graphite is particularly suitable for use as the negative electrode active material.

[0085] Examples of the conductive auxiliary material include conductive fibers such as carbon fibers, carbon nanotubes, and metal fibers, metal powders such as carbon fluoride and aluminum powder, conductive whiskers such as zinc oxide, conductive metal oxides such as titanium oxide, and organic conductive materials such as phenylene dielectrics.

[0086] (Solid Electrolyte)

[0087] In secondary batteries, solid electrolytes are placed between the positive and negative electrodes as a lithium ion transport layer and can serve as a main electrolyte, also acting as a separator. By mixing with the active material layers of the positive and negative electrodes, they can also serve as an additive to enhance lithium ion conductivity.

[0088] The polymer electrolyte disclosed herein can be used as both a main electrolyte and an auxiliary material. This allows for a larger contact interface between the main electrolyte and the positive and negative electrode active materials, while also providing flexibility to follow the expansion and contraction of the positive and negative electrode active materials, thereby improving the properties of the secondary battery.

[0089] For the main electrolyte and auxiliary materials, solid electrolytes other than polymer electrolytes may be used. Examples of solid electrolytes other than polymer electrolytes include oxide-based solid electrolytes, sulfide-based solid electrolytes, and complex hydride-based solid electrolytes.

[0090] Examples of oxide-based solid electrolytes include Li 1.5 Al 0.5 Ge 1.5 (PO4)3 and Li 1.3 Al 0.3 Ti 1.7 (PO4)3 and other NASICON compounds, as well as Li 6.25 LA3ZR2Al 0.25 O 12 Examples of oxide-based solid electrolytes include Li 0.33 Li 0.55 TiO3 and other perovskite compounds. Examples of oxide-based solid electrolytes also include Li 14Lisicon-type compounds such as Zn(GeO4)4 and acid compounds such as Li3PO4, Li4SiO4 and Li3BO3. Specific examples of sulfide-based solid electrolytes include Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, etc.

[0091] The solid electrolyte may be crystalline or amorphous, or may be glass ceramic. The symbols Li2S-P2S5 and the like refer to sulfide-based solid electrolytes made using raw materials containing Li2S and P2S5.

[0092] The polymer electrolyte of the present disclosure can be used as a main electrolyte, a positive electrode active material binder, or a negative electrode active material binder. The composition of the polymer electrolyte according to one embodiment of the present disclosure will be described in detail below.

[0093] The polymer electrolyte of the present disclosure is preferably a solid electrolyte or a semi-solid electrolyte, such as a dry polymer electrolyte or a gel electrolyte. In other words, a non-liquid electrolyte is preferred. A dry polymer electrolyte is more preferred. The polymer electrolyte preferably does not substantially contain a liquid component such as a liquid electrolyte.

[0094] <Polymer Electrolyte>

[0095] The polymer electrolyte according to one embodiment of the present disclosure has a polymer having the following structure: The polymer is, for example, a vinyl polymer. The polymer electrolyte is, for example, a polyether acrylic resin having a three-dimensional cross-linked structure having the following structure.

[0096] - A structure represented by formula (1).

[0097] - At least one structure selected from the group consisting of the structure represented by formula (2) and the structure represented by formula (3).

[0098] - A structure represented by formula (4).

[0099] The polymer electrolyte has a structure represented by the following formula (1).

[0100] [Chemical Formula 3]

[0101]

[0102] In formula (1), R 1 Represents a hydrogen atom or a methyl group. 2 represents a linear or branched alkylene group having 1 to 6 (preferably 1 to 4, more preferably 2 to 4) carbon atoms. 3 It represents an alkyl group having 1 to 6 (preferably 1 to 4, more preferably 1) carbon atoms.

[0103] In formula (1), A1 is a linking group having at least an ethylene oxide structure represented by (-CH2CH2-O-).

[0104] The structure represented by formula (1) is preferably a structure represented by the following formula (1-1).

[0105] [Chemical Formula 4]

[0106]

[0107] In formula (1-1), R 1 Represents a hydrogen atom or a methyl group. 2 represents a linear or branched alkylene group having 1 to 6 (preferably 1 to 4, more preferably 2 to 4) carbon atoms. 3 represents an alkyl group having 1 to 6 (preferably 1 to 4, more preferably 1) carbon atoms. m1 and n1 are the average number of added moles, m1 is an integer of 1 or greater (preferably 1 to 110, more preferably 13 to 46), and n1 is an integer of 0 or greater (preferably 5% to 25% of m1, more preferably 11% to 25% of m1).

[0108] The polymer electrolyte has at least one structure selected from the group consisting of a structure represented by the following formula (2) and a structure represented by the following formula (3). The at least one structure selected from the group consisting of a structure represented by the following formula (2) and a structure represented by the following formula (3) may be a structure represented by the following formula (2). This structure may form a three-dimensional cross-linked structure.

[0109] [Chemical Formula 5]

[0110]

[0111] In formula (2), R 4 Each independently represents a hydrogen atom or a methyl group. 5 and R 6 Each independently represents a linear or branched alkylene group having 1 to 6 (preferably 1 to 4, more preferably 2 to 4) carbon atoms.

[0112] In formula (3), R 7 Each independently represents a hydrogen atom or a methyl group. 8 、R 9 and R 10 Each independently represents a linear or branched alkylene group having 1 to 6 (preferably 1 to 4, more preferably 2 to 4) carbon atoms. 11 It represents a trivalent organic group having 1 to 6 (preferably 1 to 3, more preferably 1) carbon atoms.

[0113] In formulae (2) and (3), B1, D1, D2, and D3 each independently represent a linking group having at least an ethylene oxide structure represented by (—CH 2 CH 2 —O—).

[0114] In formulas (1) to (3), it is preferred that A1, B1, D1, D2, and D3 each independently further have a propylene oxide structure represented by (-CH2CH(CH3)-O-). The arrangement of the ethylene oxide structure and the propylene oxide structure may be a block copolymer or a random copolymer. Random copolymers are preferred.

[0115] Furthermore, A1, B1, D1, D2, and D3 may each independently further include a diol structure having 1 to 6 (preferably 4 to 6) carbon atoms within the range that does not impair the effects of the present disclosure. x -O- means, where R x It is an alkylene group having 1 to 6 (preferably 4 to 6) carbon atoms.

[0116] The structure represented by formula (2) is preferably a structure represented by the following formula (2-1).

[0117] [Chemical Formula 6]

[0118]

[0119] In formula (2-1), R 4 Each independently represents a hydrogen atom or a methyl group. 5 and R 6 Each independently represents a linear or branched alkylene group having 1 to 6 (preferably 1 to 4, more preferably 2 to 4) carbon atoms. m2 and n2 are the average number of added moles, m2 is an integer of 1 or greater (preferably 1 to 110, more preferably 13 to 46), and n2 is an integer of 0 or greater (preferably 5% to 25% of m2, more preferably 11% to 25% of m2).

[0120] To the extent that the effects of the present disclosure are not impaired, the chain between the two -COO- groups may further include a diol structure having 1 to 6 (preferably 4 to 6) carbon atoms. For example, the diol structure may be included between ethylene oxide structures, between propylene oxide structures, or between an ethylene oxide structure and a propylene oxide structure. The diol structure is composed of -OR x -O- means, where R x It is an alkylene group having 1 to 6 (preferably 4 to 6) carbon atoms.

[0121] The structure represented by formula (3) is preferably a structure represented by the following formula (3-1).

[0122] [Chemical Formula 7]

[0123]

[0124] In formula (3-1), R 7 Each independently represents a hydrogen atom or a methyl group. 8 、R 9 and R 10 Each independently represents a linear or branched alkylene group having 1 to 6 (preferably 1 to 4, more preferably 2 to 4) carbon atoms. 11 represents a trivalent organic group (preferably a hydrocarbon group) having 1 to 6 (preferably 1 to 3, more preferably 1) carbon atoms. m3 and n3 are the average number of added moles, and m3 independently represents an integer greater than 1 (preferably 1 to 110, more preferably 13 to 46), and n3 independently represents an integer greater than 0 (preferably 5% to 25% of m3, more preferably 11% to 25% of m3).

[0125] To the extent that the effects of the present disclosure are not impaired, 11 The chain between may further include a diol structure having 1 to 6 (preferably 4 to 6) carbon atoms. For example, the diol structure may be included between ethylene oxide structures, between propylene oxide structures, or between ethylene oxide structures and propylene oxide structures. The diol structure is composed of -OR x -O- means, where R x It is an alkylene group having 1 to 6 (preferably 4 to 6) carbon atoms.

[0126] In the polymer contained in the polymer electrolyte, the average addition mole number Meo of the ethylene oxide structure relative to 1 mole of the (meth)acryloyl residue is preferably 2.5 moles or more. Meo is more preferably 13 to 46. Within the above range, the crosslinking density of the polymer main chain becomes more appropriate, so that high lithium ion conductivity can be obtained while maintaining strength at high temperatures. The (meth)acryloyl residue is an addition polymerization form of the (meth)acryloyl group and is represented, for example, by the following structure in formula (1).

[0127] [Chemical Formula 8]

[0128]

[0129] Furthermore, in the polymer electrolyte, the average number of added moles Mpo of (meth)acryloyl residue propylene oxide structures per 1 mole is preferably 5% to 25%, and more preferably 11% to 25%, of the average number of added moles Meo of (meth)acryloyl residue ethylene oxide structures per 1 mole. Within this range, even if the molecular weight between crosslinks is high, the crystallinity of the polymer main chain is suppressed, making it easier to suppress the obstruction of lithium ion migration, particularly at low temperatures.

[0130] The average addition mole numbers Meo and Mpo can be measured by decomposing the polymer electrolyte using pyrolysis GC / MS and quantifying the fragments derived from the (meth)acryloyl residue, the fragments derived from the ethylene oxide structure, and the fragments derived from the propylene oxide structure by creating a calibration curve for each fragment.

[0131] In the polymer electrolyte of the present disclosure, the three-dimensional cross-linked structure of the polymer has a very low cross-linking density as described above, and the polymer chain has many free chains that are not bonded to other polymer chains at one end. This cross-linked structure can be obtained, for example, by reacting the following materials.

[0132] - Polyether mono(meth)acrylate.

[0133] - At least one selected from the group consisting of polyether di(meth)acrylates and polyether tri(meth)acrylates.

[0134] - An ammonium-based ionic compound having an unsaturated reactive functional group.

[0135] (Polyether mono(meth)acrylate)

[0136] The polyether mono(meth)acrylate may have a structure represented by Formula (1) (preferably Formula (1-1)). As the polyether mono(meth)acrylate, for example, at least one selected from the group consisting of polyethylene glycol mono(meth)acrylate and polyethylene glycol-propylene glycol copolymer mono(meth)acrylate may be used. When polyethylene glycol-propylene glycol copolymer mono(meth)acrylate is used, the molar ratio of ethylene glycol structure to propylene glycol structure is preferably 100:0 to 50:50, more preferably 80:20 to 95:5.

[0137] When the molar ratio of ethylene glycol structure:propylene glycol structure is within this range, the lithium ion transportability by polyethylene glycol can be maintained at a high level, and by combining with the structure of formula (4), it becomes easier to suppress the obstruction of lithium ion migration due to polymer crystallization.

[0138] Polyether mono(meth)acrylate is represented by, for example, the following formula (1').

[0139] [Chemical Formula 9]

[0140]

[0141] In formula (1'), R 1 、R 2 、R 3 , m1 and n1 are the same as those in formula (1-1).

[0142] (Polyether di(meth)acrylate)

[0143] The polyether di(meth)acrylate may have a structure represented by Formula (2) (preferably Formula (2-1)). As the polyether di(meth)acrylate, for example, at least one selected from the group consisting of polyethylene glycol di(meth)acrylate and polyethylene glycol-propylene glycol copolymer di(meth)acrylate may be used. When polyethylene glycol-propylene glycol copolymer di(meth)acrylate is used, the molar ratio of ethylene glycol structure:propylene glycol structure is preferably 100:0 to 50:50, more preferably 80:20 to 95:5.

[0144] When the molar ratio of ethylene glycol structure:propylene glycol structure is within this range, the lithium ion transportability by polyethylene glycol can be maintained at a high level, and by combining with the structure of formula (4), it becomes easier to suppress the obstruction of lithium ion migration due to polymer crystallization.

[0145] Polyether di(meth)acrylate is represented by, for example, the following formula (2').

[0146] [Chemical Formula 10]

[0147]

[0148] In formula (2'), R 4 、R 5 、R 6 , m2 and n2 are the same as those in formula (2-1).

[0149] To the extent that the effects of the present disclosure are not impaired, the chain sandwiched between the two -COO- groups may further include a diol structure having 1 to 6 (preferably 4 to 6) carbon atoms. For example, the diol structure may be included between an ethylene oxide structure and a propylene oxide structure. The diol structure is composed of -OR x -O- means, where R x It is an alkylene group having 1 to 6 (preferably 4 to 6) carbon atoms.

[0150] (Polyether tri(meth)acrylate)

[0151] The polyether tri(meth)acrylate may have a structure represented by Formula (3) (preferably Formula (3-1)). As the polyether tri(meth)acrylate, for example, at least one selected from the group consisting of polyethylene glycol tri(meth)acrylate and polyethylene glycol-propylene glycol copolymer tri(meth)acrylate may be used. When polyethylene glycol-propylene glycol copolymer tri(meth)acrylate is used, the molar ratio of ethylene glycol structure:propylene glycol structure is preferably 100:0 to 50:50, more preferably 80:20 to 95:5.

[0152] When the molar ratio of ethylene glycol structure:propylene glycol structure is within this range, the lithium ion transportability by polyethylene glycol can be maintained at a high level, and by combining with the structure of formula (4), it becomes easier to suppress the obstruction of lithium ion migration due to polymer crystallization.

[0153] Polyether tri(meth)acrylate is represented by, for example, the following formula (3').

[0154] [Chemical Formula 11]

[0155]

[0156] In formula (3'), R 7 、R 8 、R 9 、R 10 、R 11 , m3 and n3 are the same as those in formula (3-1). 11 The chain between may further include a diol structure having 1 to 6 (preferably 4 to 6) carbon atoms. For example, the diol structure may be included between the ethylene oxide structure and the propylene oxide structure. The diol structure is composed of -OR x -O- means, where R x It is an alkylene group having 1 to 6 (preferably 4 to 6) carbon atoms.

[0157] The structures represented by formulae (1), (2) and (3) (preferably formulae (1-1), (2-1) and (3-1)) can be obtained, for example, by using a polyether polyol obtained by ring-opening polymerization of ethylene oxide and propylene oxide.

[0158] The arrangement of the ethylene oxide structure represented by (-CH2-CH2-O-) and the propylene oxide structure represented by (-CH2-CH(CH3)-O-) in Formula (1-1), Formula (2-1), and Formula (3-1) (as well as Formula (1'), Formula (2'), and Formula (3')) may be a block copolymer or a random copolymer. Random copolymers are preferred.

[0159] The mass content of the structure represented by formula (1) in the polymer contained in the polymer electrolyte is represented by A. The total mass content of the structure represented by formula (2) and the structure represented by formula (3) in the polymer (preferably the mass-based content of the structure represented by formula (2)) is represented by B. The mass ratio of A to B, A:B, is preferably 70:30 to 98:2. It is more preferably 88:12 to 96:4, and even more preferably 90:10 to 95:5.

[0160] The mass ratio A:B can be adjusted in particular via the ratio of polyether mono(meth)acrylate to polyether di(meth)acrylate and / or tri(meth)acrylate.

[0161] When the mass ratio A:B is within the above range, the polymer does not have an excessively dense network structure and is less likely to hinder the migration of lithium ions while maintaining strength, and thus is particularly preferred.

[0162] In the polymer electrolyte, it is preferred that m1+n1 in formula (1-1) is 1 to 110 (more preferably 14 to 58), and m2+n2 in formula (2-1) and / or m3+n3 in formula (3-1) (preferably m2+n2 and m3+n3) are 1 to 110 (more preferably 14 to 58). Within these ranges, the crosslinking density of the polymer main chain becomes appropriate, so the ionic conductivity of the polymer electrolyte is higher while maintaining the strength at high temperatures, and the rate characteristics of the secondary battery are also improved.

[0163] In the polymer electrolyte, it is preferred that m1:n1 in formula (1-1) is 80:20 to 95:5 (more preferably 80:20 to 90:10), and m2:n2 in formula (2-1) and / or m3:n3 in formula (3-1) (preferably m2:n2 in formula (2-1) and m3:n3 in formula (3-1)) is 80:20 to 95:5 (more preferably 85:15 to 95:5).

[0164] Within the above range, even if the molecular weight between crosslinking points is large, the crystallinity of the polymer main chain is suppressed, and it becomes easier to suppress the inhibition of lithium ion migration particularly at low temperatures.

[0165] <Ammonium Cationic Group>

[0166] The polymer in the polymer electrolyte has at least one structure selected from the group consisting of structures represented by the following formula (4): For example, the structure represented by the following formula (4) may be a reaction product of an ammonium-based ionic compound having an unsaturated reactive functional group.

[0167] [Chemical Formula 12]

[0168]

[0169] In formula (4), R 12 represents a hydrogen atom or a methyl group.

[0170] R 13 Represents a divalent linking group. 14 、R 15 and R 16Each independently represents an alkyl group having 1 to 8 (preferably 1 to 4, more preferably 1 or 2, still more preferably 1) carbon atoms. - Indicates anion.

[0171] R as a linking group 13 Specifically, it represents a linear or branched alkylene group having 1 to 6 (preferably 1 to 4, more preferably 1 or 2, and even more preferably 1) carbon atoms or a divalent organic group containing an ester bond. The divalent organic group containing an ester bond is preferably an ester bond (-COO-) or a carbonyloxyalkylene group of an alkylene group having 1 to 6 (preferably 1 to 4, more preferably 1 or 2, and even more preferably 1) carbon atoms. Preferably, the carbonyl group in the divalent organic group containing an ester bond and the carbonyl group with R 12 Bonded carbon bonding.

[0172] From the perspective of lithium ion transport, the polyether composition of the polyether (meth)acrylate as the main component of the polymer is preferably polyethylene glycol. However, polyethylene glycol has high crystallinity, and to suppress crystallization, especially at low temperatures, a method is used to copolymerize propylene glycol structures with poor lithium ion transport properties at a certain ratio. As a result, it is difficult to achieve high ion conductivity using only polyether compositions having structures of formulas (1) to (3).

[0173] At the same time, the structure of formula (4) is a relatively large functional group having multiple alkyl terminal ends, so that the introduction of the structure of formula (4) into the polymer structure can reduce crystallinity. Therefore, it is possible to suppress crystallization at low temperatures while reducing the number of propylene glycol structures with poor lithium ion transport properties in the polyether composition, and maintain high ion conductivity even at low temperatures.

[0174] Furthermore, by introducing the structure of formula (4) into the polymer structure, the polymer itself becomes ionic, affinity with lithium salt is improved compared to when the structure of formula (4) is not present, and more lithium salt can be dissolved without causing its precipitation.

[0175] The content of the structure represented by formula (4) in the polymer structure is preferably 1 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 5 parts by mass, relative to 100 parts by mass of the total of the structures represented by formulae (1), (2) and (3).

[0176] When the content of formula (4) is within this range, both improved compatibility with the supporting electrolyte and improved ion conductivity at higher levels can be achieved due to reduced crystallinity.

[0177] The state after these reactions can be confirmed by analysis using known means such as pyrolysis GC / MS, FT-IR, and NMR.

[0178] The ammonium-based ionic compound having an unsaturated reactive functional group capable of forming the structure shown in formula (4) is represented by, for example, the following formula (4').

[0179] [Chemical Formula 13]

[0180]

[0181] In formula (4'), R 12 ~R 16 and X - The same as those described in formula (4).

[0182] <Anions>

[0183] The anion X shown in formula (4) - Examples include fluoroalkylsulfonyl imide anion, fluorosulfonyl imide anion, fluoroalkylsulfonate anion, fluorosulfonate anion, fluoroalkylcarboxylate anion, fluoroalkylmethide anion, fluoroborate anion, fluorophosphate anion, dicyanamide anion, thiocyanate anion, bisoxalatoborate anion, perchlorate anion, and derivatives thereof.

[0184] Specific examples of the fluoroalkylsulfonyl imide anion include fluoroalkylsulfonyl imide anions having a fluoroalkyl group having 1 to 6 carbon atoms, such as bis(trifluoromethanesulfonyl)imide anion, bis(pentafluoroethanesulfonyl)imide anion, bis(heptafluoropropanesulfonyl)imide anion, bis(nonafluorobutanesulfonyl)imide anion, bis(dodecafluoropentanesulfonyl)imide anion and bis(perfluorohexanesulfonyl)imide anion, and cyclic fluoroalkylsulfonyl imide anions such as N,N-hexafluoropropane-1,3-disulfonimide.

[0185] A specific example of the fluorosulfonyl imide anion is a bis(fluorosulfonyl)imide anion.

[0186] Specific examples of the fluoroalkylsulfonate anion include a trifluoromethanesulfonate anion, a fluoromethanesulfonate anion, a perfluoroethanesulfonate anion, a perfluoropropanesulfonate anion, a perfluorobutanesulfonate anion, a perfluoropentanesulfonate anion, a perfluorohexanesulfonate anion, and a perfluorooctanesulfonate anion.

[0187] Specific examples of the fluoroalkylcarboxylate anion include a trifluoroacetate anion, a perfluoropropionate anion, a perfluorobutyrate anion, a perfluorovalerate anion, and a perfluorohexanoate anion.

[0188] Specific examples of the fluoroalkyl methide anion include fluorinated alkylsulfonylmethyl anions such as tris(trifluoromethanesulfonyl)methide anion, tris(perfluoroethanesulfonyl)methide anion, tris(perfluoropropanesulfonyl)methide anion, tris(perfluorobutanesulfonyl)methide anion, tris(perfluoropentanesulfonyl)methide anion, tris(perfluorohexanesulfonyl)methide anion, and tris(perfluorooctanesulfonyl)methide anion.

[0189] A specific example of the fluoroborate anion is the tetrafluoroborate anion.

[0190] A specific example of the fluorophosphate anion is the hexafluorophosphate anion.

[0191] Among these anions, at least one selected from the group consisting of fluoroalkylsulfonyl imide anions, fluorosulfonyl imide anions, fluoroborate anions, dicyanamide anions, and thiocyanate anions is particularly preferable because it reduces the decrease in conductivity under low-temperature environments.

[0192] More specifically, it is preferably selected from the group consisting of bis(trifluoromethanesulfonyl)imide anion, bis(fluorosulfonyl)imide anion, trifluoromethanesulfonate anion (CF3-SO3 - ), hexafluorophosphate anion (PF6 - ), fluoroborate anion (BF4 - ), dicyanamide anion (N(CN)2 - ) and thiocyanate anion (SCN - ) is selected from the group consisting of at least one anion.

[0193] More preferably, it is preferably selected from the group consisting of bis(trifluoromethanesulfonyl)imide anion, bis(fluorosulfonyl)imide anion, hexafluorophosphate anion (PF6 - ) and dicyanamide anion (N(CN)2 - ) is selected from the group consisting of at least one anion.

[0194] <Lithium Salt>

[0195] The polymer electrolyte contains a lithium salt. The lithium salt is preferably included as a supporting electrolyte in the lithium ion secondary battery. Examples of the lithium salt include at least one selected from the group consisting of LiBF4, LiPF6, LiN(SO2CF3)2, LiN(SO2F)2, LiN(SO2C2F5)2, LiAlCl4, LiSBF6, LiSCN, LiCF3SO3, LiAsF6, LiClO4, LiN(CN)2, lower aliphatic lithium carboxylates, LiCl, LiBR, and LiI.

[0196] Among them, in terms of chemical stability to lithium-based positive electrode active materials, at least one selected from the group consisting of lithium bis(trifluoromethanesulfonyl)imide (LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiN(SO2F)2), and LiN(C2F5SO2)2 is preferred. The lithium salt can be used alone or in combination of two or more.

[0197] The content of the lithium salt is preferably 5 to 40 parts by mass, more preferably 7 to 20 parts by mass, relative to 100 parts by mass of the polymer in the polymer electrolyte. When the content of the lithium salt is within this range, the lithium salt is well compatible with the polymer and will not precipitate, and high ionic conductivity will be obtained.

[0198] The polymer electrolyte is preferably a solidified product of an electrolyte solution.

[0199] The electrolyte solution may be, for example, a mixture of the following materials.

[0200] - Polyether mono(meth)acrylate.

[0201] - At least one selected from the group consisting of polyether di(meth)acrylates and polyether tri(meth)acrylates.

[0202] - An ammonium-based ionic compound having an unsaturated reactive functional group.

[0203] -lithium salts.

[0204] The electrolyte solution may contain a known polymerization initiator as needed. Examples of the polymerization initiator include photopolymerization initiators.

[0205] <Liquid Electrolyte>

[0206] The polymer electrolyte may contain a liquid electrolyte within the range that does not impair the effects of the present disclosure and does not impair safety at high temperatures. Examples of the liquid electrolyte include ionic liquids and non-aqueous electrolytes.

[0207] Specific examples of the ionic liquid include the following combinations of cations and anions.

[0208] The cation may be at least one selected from the group consisting of quaternary ammonium, imidazolium, pyridinium, pyrrolidinium, and piperidinium.

[0209] The anion may be at least one selected from the group consisting of fluoroalkylsulfonyl imide anion, fluorosulfonyl imide anion, fluoroalkylsulfonate anion, fluorosulfonate anion, fluoroalkylcarboxylate anion, fluoroalkylmethide anion, fluoroborate anion, fluorophosphate anion, dicyanamide anion, thiocyanate anion, bisoxalatoborate anion, perchlorate anion, and derivatives thereof.

[0210] A non-aqueous electrolyte is a liquid in which about 1 mole of a lithium salt is dissolved in a non-aqueous solvent. Examples of non-aqueous solvents include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate. Examples of lithium salts include LiPF6, LiBF4, and LiClO4.

[0211] Although the inclusion of a liquid electrolyte can improve ionic conductivity, in order to avoid a decrease in mechanical strength at high temperatures, the liquid electrolyte is preferably included in an amount of, for example, 10 parts by mass or less, 5 parts by mass or less, 1 part by mass or less, or 0.5 parts by mass or less relative to 100 parts by mass of the polymer contained in the polymer electrolyte.

[0212] If necessary, the polymer electrolyte may contain non-conductive fillers such as silica, quartz powder, titanium oxide, zinc oxide, and calcium carbonate. By adding a non-conductive filler to the coating for forming the electrolyte layer, the filler acts as a film-forming aid when the coating is applied during the electrolyte layer formation process. The content of this non-conductive filler is preferably 0.1 to 10 parts by mass per 100 parts by mass of the polymer forming the electrolyte layer.

[0213] Furthermore, the polymer electrolyte may contain a conductive filler as needed within a range that does not hinder the effects of the present disclosure. As the conductive filler, conductive fine particles such as carbon black, zinc oxide, tin oxide, and titanium oxide can be used.

[0214] In particular, when a polymer electrolyte is used as a positive or negative electrode active material binder, the internal resistance of the secondary battery can be reduced by including a conductive filler in the polymer electrolyte. The content of the conductive filler is preferably 0.5 to 5 parts by mass relative to 100 parts by mass of the polymer contained in the polymer electrolyte.

[0215] (Method for Forming Polymer Electrolyte Layer)

[0216] The method for forming the polymer electrolyte layer is not particularly limited. For example, the above-mentioned polymer electrolyte materials are used and mixed by a known method to obtain an electrolyte solution for forming the polymer electrolyte layer. After the electrolyte solution is applied by a known coating method such as rod coating, spin coating or roller coating, the polymer material contained in the electrolyte solution is polymerized by a known means such as UV to form the polymer electrolyte layer. The polymer electrolyte layer can be formed at a desired position such as on the positive electrode or negative electrode.

[0217] The thickness of the polymer electrolyte layer as the main electrolyte is preferably 5.0 μm to 100.0 μm.

[0218] Example

[0219] Specific examples and comparative examples related to the present disclosure are shown below. However, the present disclosure is not limited to the following examples and comparative examples.

[0220] First, polyether acrylates having the structures shown in formula (1) and formula (2) are synthesized. An example of the synthesis of polyether monoacrylates having the structure shown in formula (1) is shown below.

[0221] <Synthesis of Polyether Monoacrylate>

[0222] (Polyether monoacrylate A-1)

[0223] A total of 15.5 parts by mass of 1-hexanol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and while maintaining the pressure inside the container at about 0.5 MPa, 1041 parts by mass of a gas mixture of ethylene oxide / propylene oxide with a molar ratio of 8:2 was continuously introduced over 260 minutes. The temperature was maintained at 100°C, and the reaction was carried out for 180 minutes until the pressure inside the container became 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and the mixture was stirred until the pressure change inside the container became 0.01 MPa / 30 minutes. A total of 20 parts by mass of pure water was added to the obtained polymer, stirred at 90°C for 30 minutes, and then 50 g of an alkaline adsorbent, Kyowaad 600 (manufactured by Kyowa Chemical Industry Co., Ltd.), was added and the mixture was stirred for another 30 minutes. The alkaline adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 6000.

[0224] Next, 100 parts by mass of the obtained polyether monool, 1.26 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 2.02 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 5 hours while removing water generated by the reaction to the outside of the system.

[0225] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% sodium hydroxide aqueous solution and further washed three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-1.

[0226] (Polyether monoacrylate A-2)

[0227] A total of 18.6 parts by mass of 1-hexanol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C for dissolution and dehydration. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and while maintaining the pressure inside the container at approximately 0.5 MPa, 976 parts by mass of a gaseous mixture of ethylene oxide and propylene oxide at a molar ratio of 95:5 was continuously introduced over 240 minutes. The temperature was maintained at 100°C, and the reaction was carried out for 180 minutes until the pressure inside the container became 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and the mixture was stirred until the pressure change inside the container reached 0.01 MPa / 30 minutes. A total of 20 parts by mass of pure water was added to the obtained polymer, and the mixture was stirred at 90°C for 30 minutes. Then, 50 g of an alkaline adsorbent Kyowaad 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred for another 30 minutes. The alkaline adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 5000.

[0228] Next, 100 parts by mass of the obtained polyether monool, 1.51 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 2.42 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 5 hours while removing water generated by the reaction to the outside of the system.

[0229] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% sodium hydroxide aqueous solution and further washed three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-2.

[0230] (Polyether monoacrylate A-3)

[0231] Polyether monoacrylate A-3 was obtained in the same manner as polyether monoacrylate A-2, except that the molar ratio of the ethylene oxide / propylene oxide mixed gas was changed to 8:2.

[0232] (Polyether monoacrylate A-4)

[0233] A total of 33.7 parts by mass of 1-butanol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and while maintaining the pressure inside the container at about 0.5 MPa, 984 parts by mass of a gas mixture of ethylene oxide / propylene oxide with a molar ratio of 8:2 was continuously introduced over 240 minutes. The temperature was maintained at 100°C, and the reaction was carried out for 150 minutes until the pressure inside the container became 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and the mixture was stirred until the pressure change inside the container became 0.01 MPa / 30 minutes. A total of 20 parts by mass of pure water was added to the obtained polymer, and the mixture was stirred at 90°C for 30 minutes. Then, 50 g of an alkaline adsorbent, Kyowaad 600 (manufactured by Kyowa Chemical Industry Co., Ltd.), was added and the mixture was stirred for another 30 minutes. The alkaline adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 2000.

[0234] Next, 100 parts by mass of the obtained polyether monool, 3.78 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 6.05 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 6 hours while removing water generated by the reaction to the outside of the system.

[0235] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% sodium hydroxide aqueous solution and further washed three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-4.

[0236] (Polyether monoacrylate A-5)

[0237] A total of 67.4 parts by mass of 1-butanol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and while maintaining the pressure inside the container at about 0.5 MPa, 946 parts by mass of a gas mixture of ethylene oxide / propylene oxide with a molar ratio of 8:2 was continuously introduced over 240 minutes. The temperature was maintained at 100°C, and the reaction was carried out for 130 minutes until the pressure inside the container became 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and the mixture was stirred until the pressure change inside the container became 0.01 MPa / 30 minutes. A total of 20 parts by mass of pure water was added to the obtained polymer, and the mixture was stirred at 90°C for 30 minutes. Then, 50 g of an alkaline adsorbent Kyowaad 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred for another 30 minutes. The alkaline adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 1000.

[0238] Next, 100 parts by mass of the obtained polyether monool, 7.56 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 12.1 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 6 hours while removing water generated by the reaction to the outside of the system.

[0239] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-5.

[0240] (Polyether monoacrylate A-6)

[0241] A total of 112 parts by mass of 1-butanol (Tokyo Chemical Industry Co., Ltd.) and 5 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and while maintaining the pressure inside the container at about 0.5 MPa, 937 parts by mass of a gas mixture of ethylene oxide / propylene oxide with a molar ratio of 8:2 was continuously introduced over 240 minutes. The temperature was maintained at 100°C, and the reaction was carried out for 120 minutes until the pressure inside the container became 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and the mixture was stirred until the pressure change inside the container became 0.01 MPa / 30 minutes. A total of 20 parts by mass of pure water was added to the obtained polymer, and the mixture was stirred at 90°C for 30 minutes. Then, 50 g of an alkaline adsorbent, Kyowaad 600 (manufactured by Kyowa Chemical Industry Co., Ltd.), was added and the mixture was stirred for another 30 minutes. The alkaline adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 600.

[0242] Next, 100 parts by mass of the obtained polyether monool, 12.6 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 20.2 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 6 hours while removing water generated by the reaction to the outside of the system.

[0243] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-6.

[0244] (Polyether monoacrylate A-7)

[0245] A total of 169 parts by mass of 1-butanol (Tokyo Chemical Industry Co., Ltd.) and 8 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and while maintaining the pressure inside the container at about 0.5 MPa, 927 parts by mass of a gas mixture of ethylene oxide / propylene oxide with a molar ratio of 8:2 was continuously introduced over 220 minutes. The temperature was maintained at 100°C, and the reaction was carried out for 120 minutes until the pressure inside the container became 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and the mixture was stirred until the pressure change inside the container became 0.01 MPa / 30 minutes. A total of 20 parts by mass of pure water was added to the obtained polymer, and the mixture was stirred at 90°C for 30 minutes. Then, 50 g of an alkaline adsorbent, Kyowaad 600 (manufactured by Kyowa Chemical Industry Co., Ltd.), was added and the mixture was stirred for another 30 minutes. The alkaline adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 400.

[0246] Next, 100 parts by mass of the obtained polyether monool, 18.9 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 24.2 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 6 hours while removing water generated by the reaction to the outside of the system.

[0247] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% sodium hydroxide aqueous solution and three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-7.

[0248] (Polyether monoacrylate A-8)

[0249] Polyether monoacrylate A-8 was obtained in the same manner as polyether monoacrylate A-5, except that the molar ratio of the ethylene oxide / propylene oxide mixed gas was changed to 9:1.

[0250] (Polyether monoacrylate A-9)

[0251] Polyether monoacrylate A-9 was obtained in the same manner as polyether monoacrylate A-5, except that the molar ratio of the ethylene oxide / propylene oxide mixed gas was changed to 5:5.

[0252] (Polyether monoacrylate A-10)

[0253] A polyether monool with Mn 600 was obtained in the same manner as in the preparation of polyether monoacrylate A-6, except that the molar ratio of the ethylene oxide / propylene oxide mixed gas was changed to 5:5.

[0254] Next, 100 parts by mass of the obtained polyether monool, 15.0 parts by mass of methacrylic acid (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 20.2 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reactor equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 6 hours while removing water generated by the reaction to the outside of the system.

[0255] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and further washed three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether monomethacrylate A-10.

[0256] (Polyether monoacrylate A-11)

[0257] A polyether monool having an Mn of 400 was obtained in the same manner as in the preparation of polyether monoacrylate A-7, except that the molar ratio of the ethylene oxide / propylene oxide mixed gas was changed to 5:5.

[0258] Next, 100 parts by mass of the obtained polyether monool, 22.6 parts by mass of methacrylic acid (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 24.2 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 6 hours while removing water generated by the reaction to the outside of the system.

[0259] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and further washed three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether monomethacrylate A-11.

[0260] Table 1 shows the obtained polyether mono(meth)acrylates.

[0261] Next, a synthesis example of a polyether diacrylate which can form the structure shown in formula (2) will be described.

[0262] <Synthesis of Polyether Diacrylate>

[0263] (Polyether diacrylate B-1)

[0264] A total of 13.7 parts by mass of 1,4-butanediol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and while maintaining the pressure inside the container at about 0.5 MPa, 1041 parts by mass of a gas mixture of ethylene oxide / propylene oxide with a molar ratio of 8:2 was continuously introduced over 280 minutes. The temperature was maintained at 100°C, and the reaction was carried out for 170 minutes until the pressure inside the container became 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and the mixture was stirred until the pressure change inside the container became 0.01 MPa / 30 minutes. A total of 20 parts by mass of pure water was added to the obtained polymer, and the mixture was stirred at 90°C for 30 minutes. Then, 50 g of an alkaline adsorbent, Kyowaad 600 (manufactured by Kyowa Chemical Industry Co., Ltd.), was added and the mixture was stirred for another 30 minutes. The alkaline adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether diol having an Mn of 6000.

[0265] Next, 100 parts by mass of the obtained polyether diol, 2.52 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 2.02 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 5 hours while removing water generated by the reaction to the outside of the system.

[0266] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% sodium hydroxide aqueous solution and further washed three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-1.

[0267] (Polyether diacrylate B-2)

[0268] A polyether diol having Mn 5000 was obtained in the same manner as in the preparation of polyether diacrylate B-1, except that the amount of 1,4-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) was changed to 16.4 parts by mass.

[0269] Next, 100 parts by mass of the obtained polyether diol, 3.02 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 2.42 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 5 hours while removing water generated by the reaction to the outside of the system.

[0270] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and further washed three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-2.

[0271] (Polyether diacrylate B-3)

[0272] A total of 41.0 parts by mass of 1,4-butanediol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and while maintaining the pressure inside the container at about 0.5 MPa, 955 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar ratio of 9:1 was continuously introduced over 220 minutes. The temperature was maintained at 100°C, and the reaction was carried out for 150 minutes until the pressure inside the container became 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and the mixture was stirred until the pressure change inside the container became 0.01 MPa / 30 minutes. A total of 20 parts by mass of pure water was added to the obtained polymer, and the mixture was stirred at 90°C for 30 minutes. Then, 50 g of an alkaline adsorbent Kyowaad 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred for another 30 minutes. The alkaline adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether diol having an Mn of 2000.

[0273] Next, 100 parts by mass of the obtained polyether diol, 7.56 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 6.05 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reactor equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 5 hours while removing water generated by the reaction to the outside of the system.

[0274] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-3.

[0275] (Polyether diacrylate B-4)

[0276] A total of 205 parts by mass of 1,4-butanediol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and while maintaining the pressure inside the container at about 0.5 MPa, 899 parts by mass of a gas mixture of ethylene oxide / propylene oxide with a molar ratio of 9:1 was continuously introduced over 210 minutes. The temperature was maintained at 100°C, and the reaction was carried out for 110 minutes until the pressure inside the container became 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and the mixture was stirred until the pressure change inside the container became 0.01 MPa / 30 minutes. A total of 20 parts by mass of pure water was added to the obtained polymer, and the mixture was stirred at 90°C for 30 minutes. Then, 50 g of an alkaline adsorbent, Kyowaad 600 (manufactured by Kyowa Chemical Industry Co., Ltd.), was added and the mixture was stirred for another 30 minutes. The alkaline adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether diol having an Mn of 400.

[0277] Next, 100 parts by mass of the obtained polyether diol, 37.8 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 24.2 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reactor equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 6 hours while removing water generated by the reaction to the outside of the system.

[0278] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-4.

[0279] (Polyether diacrylate B-5)

[0280] A polyether diol having an Mn of 600 was obtained in the same manner as in the preparation of polyether diacrylate B-4, except that the amount of 1,4-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) was changed to 137 parts by mass.

[0281] Next, 100 parts by mass of the obtained polyether diol, 25.2 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 20.2 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reactor equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 6 hours while removing water generated by the reaction to the outside of the system.

[0282] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-5.

[0283] (Polyether diacrylate B-6)

[0284] A polyether diol having an Mn of 1000 was obtained in the same manner as in the preparation of polyether diacrylate B-3, except that the amount of 1,4-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) was changed to 82.0 parts by mass.

[0285] Next, 100 parts by mass of the obtained polyether diol, 15.1 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 12.1 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115° C. and reacted for 6 hours while removing water generated by the reaction to the outside of the system.

[0286] The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% sodium hydroxide aqueous solution and further washed three times with 120 g of pure water. The organic phase was separated from the washed reaction solution by fractional distillation, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-6.

[0287] (Polyether diacrylate B-7)

[0288] Polyether diacrylate B-7 was obtained in the same manner as polyether diacrylate B-2, except that the molar ratio of the ethylene oxide / propylene oxide mixed gas was changed to 9:1.

[0289] (Polyether diacrylate B-8)

[0290] A polyether diol having an Mn of 1000 was obtained in the same manner as in the preparation of polyether diacrylate B-6, except that the molar ratio of the ethylene oxide / propylene oxide mixed gas was changed to 5:5.

[0291] Next, 100 parts by mass of the obtained polyether diol, 18.1 parts by mass of methacrylic acid (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 12.1 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115°C and reacted for 6 hours while removing the water generated by the reaction to the outside of the system. Polyether diacrylate B-8 was then obtained in the same manner as for polyether diacrylate B-6.

[0292] (Polyether diacrylate B-9)

[0293] A polyether diol with an Mn of 600 was obtained in the same manner as in the preparation of polyether diacrylate B-5, except that the molar ratio of the ethylene oxide / propylene oxide mixed gas was changed to 5:5.

[0294] Next, 100 parts by mass of the obtained polyether diol, 30.0 parts by mass of methacrylic acid (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 20.2 parts by mass of p-toluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were placed in a Dean-Stark reaction apparatus equipped with a stirring device. The mixture was heated and stirred at 115°C and reacted for 5 hours while removing water generated by the reaction to the outside of the system. Polyether diacrylate B-9 was then obtained in the same manner as for polyether diacrylate B-6.

[0295] Table 2 shows the obtained polyether di(meth)acrylates.

[0296] [Table 1]

[0297] Table 1

[0298]

[0299] The polyether composition ratio is expressed as a mole fraction. EO represents ethylene oxide, and PO represents propylene oxide.

[0300] [Table 2]

[0301] Table 2

[0302]

[0303] The polyether composition ratio is expressed as a mole fraction. EO represents ethylene oxide, and PO represents propylene oxide.

[0304] <Synthesis of Reactive Ionic Compounds>

[0305] (Synthesis of Ionic Compound C-1)

[0306] A total of 15.0 g (0.11 mol) of allyltrimethylammonium chloride (Combi-Blocks Inc.) was dissolved in 160 mL of pure water. A total of 31.7 g (0.11 mol) of lithium bis(trifluoromethanesulfonyl)imide (trade name: EF-N115, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) was added as an anion raw material, and stirred at room temperature for 1 hour. Next, the reaction solution was extracted twice with 100.0 g of ethyl acetate. The separated ethyl acetate layer was then washed three times with 60 g of ion-exchanged water. Ethyl acetate was then distilled off under reduced pressure to obtain ionic compound C-1.

[0307] (Synthesis of Ionic Compound C-2)

[0308] A total of 15.0 g (0.11 mol) of allyltrimethylammonium chloride (Combi-Blocks Inc.) was dissolved in 160 mL of pure water. A total of 9.8 g (0.11 mol) of sodium dicyanamide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as an anion raw material and stirred at room temperature for 1 hour. Next, the reaction solution was extracted twice with 100.0 g of ethyl acetate. Next, the separated ethyl acetate layer was washed three times with 60 g of ion-exchanged water. Then, ethyl acetate was distilled off under reduced pressure to obtain ionic compound C-2.

[0309] (Synthesis of Ionic Compound C-3)

[0310] A total of 12.1g (0.06mol) 8-bromo-1-octene (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 15.0g (0.06mol) trimethylamine (about 25% ethanol solution, about 3mol / L) (manufactured by Tokyo Chemical Industry Co., Ltd.), and the reaction system was placed in a nitrogen atmosphere and then stirred at room temperature for 43h. The solvent was distilled off under reduced pressure, and the mixture was washed 3 times with 100.0g n-hexane. The upper layer was removed by separation, and the solvent was distilled off under reduced pressure. The product therefrom was dissolved in 160mL pure water. A total of 9.6g (0.06mol) lithium hexafluorophosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as an anion raw material, and stirred at room temperature for 1h. Then, the reaction solution was extracted 2 times with 100.0g ethyl acetate. Then, the separated ethyl acetate layer was washed 3 times with 60g ion exchange water. Then, ethyl acetate was distilled off under reduced pressure to obtain ionic compound C-3.

[0311] (Synthesis of Ionic Compound C-4)

[0312] (2-Acryloyloxyethyl)trimethylammonium=bis(trifluoromethanesulfonyl)imide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as it was.

[0313] (Synthesis of Ionic Compound C-5)

[0314] A total of 15.0 g (0.06 mol) of [2-(acryloyloxy)ethyl]trimethylammonium chloride solution (manufactured by Merck & Co., Inc.) was dissolved in 160 mL of pure water. A total of 11.6 g (0.06 mol) of lithium bis(fluorosulfonyl)imide (manufactured by Kanto Chemical Co., Inc.) was added as an anion raw material, and stirred at room temperature for 1 hour. Next, the reaction solution was extracted twice with 100.0 g of ethyl acetate. The separated ethyl acetate layer was then washed three times with 60 g of ion-exchanged water. The ethyl acetate was then distilled off under reduced pressure to obtain ionic compound C-5.

[0315] (Synthesis of Ionic Compound C-6)

[0316] N-[2-(Methacryloxy)ethyl]-N,N-dimethylbutane-1-ammonium bis(trifluoromethanesulfonyl)imide (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as it was.

[0317] (Synthesis of Ionic Compound C-7)

[0318] 15.0g (0.10mol) (dimethylamino) methyl 2-methyl-2-acrylate ((dimethylamino) methyl 2-methylprop-2-enoate) (manufactured by Hong Kong Chemhere Co., Ltd.) is dissolved in 30.0g tetrahydrofuran (THF). The reaction system is then placed in a nitrogen atmosphere and ice-cooled. Then, 20.2g (0.10mol) 1-bromooctane (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 60.0g tetrahydrofuran (THF) is added dropwise in 30min. After the reaction solution is heated to reflux for 9h, 100mL water is added and the solvent is distilled off under reduced pressure. 100mL ethanol is added to the residue and stirred at room temperature. Insoluble matter is removed by filtration through diatomaceous earth, and the solvent is distilled off under reduced pressure again.

[0319] The resulting product was dissolved in 160 mL of pure water, and 30.1 g (0.10 mol) of lithium bis(trifluoromethanesulfonyl)imide (trade name: EF-N115, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) was added as an anion raw material, and stirred at room temperature for 1 hour. Next, the reaction solution was extracted twice with 100.0 g of ethyl acetate. Next, the separated ethyl acetate layer was washed three times with 60 g of ion-exchanged water. Then, the ethyl acetate was distilled off under reduced pressure to obtain ionic compound C-7.

[0320] (Synthesis of Ionic Compound C-8)

[0321] A total of 15.0g (0.08mol) 2-(diethylamino) ethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 30.0g tetrahydrofuran. The reaction system was placed in a nitrogen atmosphere and ice-cooled. Then, 8.8g (0.08mol) bromoethane (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 60.0g tetrahydrofuran was added dropwise in 30min. After the reaction solution was heated to reflux for 9h, 100mL water was added and the solvent was distilled off under reduced pressure. A total of 100mL ethanol was added to the residue and stirred at room temperature. Insoluble matter was removed by filtration through diatomaceous earth, and the solvent was distilled off under reduced pressure again.

[0322] The resulting product was dissolved in 160 mL of pure water, and 23.2 g (0.10 mol) of lithium bis(trifluoromethanesulfonyl)imide (trade name: EF-N115, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) was added as an anion raw material, and stirred at room temperature for 1 hour. Next, the reaction solution was extracted twice with 100.0 g of ethyl acetate. Next, the separated ethyl acetate layer was washed three times with 60 g of ion-exchanged water. Then, the ethyl acetate was distilled off under reduced pressure to obtain ionic compound C-8.

[0323] (Synthesis of Ionic Compound C-9)

[0324] After the reaction system was placed in a nitrogen atmosphere, a total of 14.0 g (0.06 mol) of 4-bromobutyl methacrylate (manufactured by Hong Kong Chemhere Co., Ltd.) dissolved in 40.0 g of ethanol was added dropwise to 15.0 g (0.06 mol) of trimethylamine (about 25% ethanol solution, about 3 mol / L) (manufactured by Tokyo Chemical Industry Co., Ltd.) over 30 minutes. The reaction solution was heated under reflux for 6 hours, and the solvent was distilled off under reduced pressure.

[0325] The resulting product was dissolved in 160 mL of pure water, and 18.2 g (0.06 mol) of lithium bis(trifluoromethanesulfonyl)imide (trade name: EF-N115, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) was added as an anion raw material, and stirred at room temperature for 1 hour. Next, the reaction solution was extracted twice with 100.0 g of ethyl acetate. Next, the separated ethyl acetate layer was washed three times with 60 g of ion-exchanged water. Then, the ethyl acetate was distilled off under reduced pressure to obtain ionic compound C-9.

[0326] The chemical structures of the obtained reactive ionic compounds are shown in Formulas C-1 to C-9.

[0327] [Chemical Formula 14]

[0328]

[0329] [Chemical Formula 15]

[0330]

[0331] <Preparation of Electrolyte Solution of Polymer Electrolyte>

[0332] [Example 1]

[0333] As materials of the polymer electrolyte, the following materials were mixed and stirred.

[0334] - Polyether monoacrylate NK ester M-230G (manufactured by Shin-Nakamura Chemical Co., Ltd.): 50.0 parts by mass

[0335] -Polyether diacrylate B-1: 50.0 parts by mass

[0336] -Ionic compound C-3: 2.0 parts by mass

[0337] -Lithium bis(trifluoromethanesulfonyl)imide (Li·TFSI) (manufactured by Kishida Chemical Co., Ltd.): 10.0 parts by mass

[0338] - Initiator Omnirad 184 (IGM RESINS BV): 2.0 parts by mass

[0339] Next, methyl ethyl ketone (hereinafter referred to as MEK) was added so as to have a total solid content ratio of 60% by mass, and the mixture was mixed with a motor stirrer to prepare an electrolyte solution.

[0340] (Measurement of volume swelling ratio by MEK immersion method)

[0341] Using the electrolyte solutions of each example, test pieces for volume swelling ratio were prepared by MEK immersion as follows. A prescribed amount of the surface layer-forming dispersion of each example was added to an aluminum mold coated with a fluororesin to achieve a film thickness of 200 μm. The mold was then placed on a sunflower stand and dried until the viscosity increased to a point where the film surface did not flow. The mold was then placed on a horizontal platform and dried at 60°C for 2 hours.

[0342] Then, a high-pressure mercury UV irradiation device (trade name: Handy 1000, manufactured by Mario Network Co., Ltd.) was used to irradiate the film surface at 5000 mJ / cm 2 The accumulated light amount is irradiated with UV light to crosslink and solidify the polymer electrolyte.

[0343] After curing, the mold was left at 23°C and 40% RH for 24 hours, and the electrolyte membrane was peeled from the aluminum mold to prepare a sheet with a film thickness of 200 μm. The obtained polymer electrolyte sheet was cut into 50 mm × 50 mm pieces and left at 23°C and 40% RH for 24 hours to prepare a test piece.

[0344] First, measure the initial weight in air (W1) and the initial weight in water (W2) at 23°C and 40% humidity. Next, immerse the test piece after the initial weight measurement in MEK at 23°C for 48 hours. Immediately after removing the test piece from the MEK, wipe the MEK on the surface with a non-woven fabric, place the test piece in a pre-weighed weighing bottle, and measure the weight after immersion in air (W3) and the weight after immersion in water (W4). Calculate the volume swelling rate after immersion in MEK using the following formula.

[0345] Volume swelling ratio (%) = ((W3-W4)-(W1-W2)) / (W1-W2)×100

[0346] W1: initial weight in air

[0347] W2: initial weight in water

[0348] W3: Weight after immersion in air

[0349] W4: Weight after immersion in water

[0350] (Measurement of ionic conductivity at room temperature (25°C))

[0351] The electrolyte solution obtained in Example 1 was coated on an aluminum plate having a thickness of 100 μm using a bar coater and dried at 60° C. for 30 min. Next, a high-pressure mercury UV irradiation device (trade name: Handy1000, manufactured by Mario Network Co., Ltd.) was used to irradiate the membrane surface at a rate of 5000 mJ / cm 2 The accumulated light amount was irradiated with UV light, and the polymer electrolyte membrane of Example 1 was cross-linked and cured. The thickness of the film after curing was 60 μm.

[0352] The obtained polymer electrolyte membrane was punched out with an aluminum substrate to a diameter of 50 mm and vacuum dried at 80° C. for 48 h. Then, the polymer electrolyte membrane was placed in an argon-substituted glove box (temperature 25° C., dew point -70° C.), and the AC impedance between the electrodes was measured using an impedance analyzer E4990A (manufactured by KEYSIGHT) at an applied voltage of 10 mV and a frequency range of 100 MHz to 1 Hz. The bulk resistance R was determined from the real impedance intercept of the obtained Cole-Cole plot. B (Ω), and the ionic conductivity was calculated using the following formula:

[0353] σ=L / R B ×S

[0354] (σ: ionic conductivity (S·cm -1 ), L: sample thickness (cm), S: sample area (cm 2 )).

[0355] (Measurement of ionic conductivity at low temperature (5°C))

[0356] In the same manner as for the measurement of ionic conductivity at room temperature, a polymer electrolyte membrane was formed on an aluminum plate. The polymer electrolyte membrane was then placed in an argon-substituted glove box (temperature 25°C, dew point -70°C) and assembled into an all-solid-state battery evaluation unit (manufactured by Hohsen Corp.).

[0357] The evaluation cell assembled with the polymer electrolyte membrane was placed in a low-temperature environmental tester and allowed to stand for 1 hour at 5° C. The ion conductivity at low temperature was then determined in the same manner as in the above-mentioned measurement.

[0358] <Preparation of Secondary Battery>

[0359] 1. Composition using the polymer electrolyte disclosed herein as the main electrolyte

[0360] (Preparation of negative electrode)

[0361] A 20 mm x 20 mm, 60 μm thick lithium foil (manufactured by Honjo Metal Co., Ltd.) was stacked on a 20 mm x 30 mm, 20 μm thick copper foil, leaving a 10 mm non-stacked end on one side, and then pressed to prepare a negative electrode. The total thickness of the prepared negative electrode was 70 μm. A 5 mm wide nickel-plated copper tab was attached to the non-stacked end on one side of the negative electrode.

[0362] (Preparation of positive electrode)

[0363] A total of 100 parts by mass of lithium cobalt oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 7 parts by mass of Kureha KH Polymer L#1120 (manufactured by Kureha Corporation) as an active material binder and 5 parts by mass of Denka Black Li-100 (manufactured by Denka Corporation) as a conductive auxiliary material. 40 parts by mass of N-methylpyrrolidone was added, mixed, and stirred. The resulting slurry was then applied to a 15 mm × 25 mm, 20 μm thick rolled aluminum foil, leaving a 10 mm non-coated edge on one side, and then dried at 100°C for 30 minutes and pressed to obtain a positive electrode. The thickness of the positive electrode was 80 μm.

[0364] A 5 mm wide aluminum tab was joined to the non-coated end portion of one side of the positive electrode.

[0365] (Formation of Polymer Electrolyte Layer)

[0366] The electrolyte solution was applied to the entire surface of the obtained positive electrode coated with the active material using a bar coater, air-dried at 23°C for 10 minutes, and then dried at 60°C for 30 minutes. Next, a high-pressure mercury UV irradiation device (trade name: Handy1000, manufactured by Mario Network Co., Ltd.) was used to irradiate the membrane surface at 5000 mJ / cm 2 The film was irradiated with UV light with a cumulative light amount of 100 μm to perform curing. The thickness of the film after curing was 60 μm.

[0367] (Preparation of a Secondary Battery Using a Polymer Electrolyte as a Main Electrolyte)

[0368] The positive electrode coated with the polymer electrolyte was vacuum dried at 80 ° C for 48 h. Then, the polymer electrolyte membrane was placed in an argon-substituted glove box (temperature 25 ° C, dew point -70 ° C), and a polyimide sheet punched into a window frame shape was attached to cover the peripheral portion of the positive electrode surface to form a short circuit prevention layer. Next, the polymer electrolyte layer of the positive electrode coated with the polymer electrolyte was stacked in a manner corresponding to the lithium layer of the negative electrode. The stack was sandwiched between aluminum laminate films and vacuum packaged to obtain a secondary battery according to Example 1.

[0369] <Evaluation of Battery Characteristics>

[0370] (Rate characteristics)

[0371] The theoretical capacity was determined from the total mass of lithium cobalt oxide contained in the positive electrode.A charge / discharge test was performed on the prototype secondary battery at 25°C by using a charge / discharge apparatus BCS-805 (manufactured by BioLogic Co., Ltd.).

[0372] The theoretical capacity is determined by the total mass of lithium cobalt oxide contained in the positive electrode, and in the first cycle,

[0373] - Charged by constant current charging at a charge rate of 0.05C and a cut-off value of 3.9V for 2h, and

[0374] - Discharge was performed by constant current discharge at a discharge rate of 0.05C and a cutoff value of 2.0V for 1 h.

[0375] Then, similar charging and discharging were performed by increasing the charging rate and the discharging rate by 0.05 C each time, and the rate at which the battery could be charged and discharged without exceeding the cutoff value was determined as the rate characteristic.

[0376] (Strength evaluation at high temperature)

[0377] The prototype secondary battery was subjected to a single impact test at 25°C using a thin film impact tester QC-633 (manufactured by Cometech Testing MAchines Co., Ltd.) with an impact tip diameter of 38.1 mm, a load of 120 g, and a height of 150 mm. The battery was then subjected to a short-circuit test using the tester. For each example, five batteries were manufactured, and a total of five impact tests were performed, and the number of batteries that short-circuited was counted.

[0378] The impact tester and the secondary battery were then placed in an environmental tester set at 60° C. and allowed to stand for 2 hours. The same test was performed, and the number of batteries that were short-circuited in the high-temperature test was counted.

[0379] [Examples 2 to 34]

[0380] Polymer electrolytes and secondary batteries according to Examples 2 to 34 were prepared in the same manner as in Example 1 except that the types and compounding amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compound, and supporting electrolyte were changed as shown in Table 3.

[0381] [Table 3]

[0382] Table 3

[0383]

[0384] The structures of the materials used in the polymerization are as follows.

[0385] M-230G (methoxy polyethylene glycol methacrylate; in formula (1-1), R 1 :Methyl, R 2 :ethylene-(CH2)2-, R 3 : methyl, m1:23, n1:0)

[0386] AM-130G (methoxy polyethylene glycol #600 acrylate; in formula (1-1), R 1 : hydrogen atom, R 2 :ethylene, R 3 : methyl, m1:13, n1:0)

[0387] AM-230G (methoxy polyethylene glycol #1000 acrylate; in formula (1-1), R 1 : hydrogen atom, R 2 :ethylene, R 3 : methyl, m1:23, n1:0)

[0388] AM-90G (methoxy polyethylene glycol #400 acrylate; in formula (1-1), R 1 : hydrogen atom, R 2 :ethylene, R 3 : methyl, m1:9, n1:0)

[0389] M-450G (methoxy polyethylene glycol methacrylate; in formula (1-1), R 1 :Methyl, R 2 :ethylene, R 3 : methyl, m1:45, n1:0)

[0390] A-1000PER (In formula (2-1), R 4 : hydrogen atom, R 5 : ethylene or propylene, R 6 : ethylene or propylene, m2: 17, n2: 4)

[0391] A-1000 (polyethylene glycol #1000 diacrylate; in formula (2-1), R 4 : hydrogen atom, R 5 :ethylene, R 6 : ethylene, m2:23, n2:0)

[0392] A-400 (polyethylene glycol #400 diacrylate; in formula (2-1), R 4 : hydrogen atom, R 5 :ethylene, R 6 : ethylene, m2:9, n2:0)

[0393] A-600 (polyethylene glycol #600 diacrylate; in formula (2-1), R 4 : hydrogen atom, R 5 :ethylene, R 6 : ethylene, m2:14, n2:0)

[0394] A-GLY-20E (ethoxylated glyceryl triacrylate; in formula (3-1), R 7 : hydrogen atom, R 8 :ethylene, R 9 :ethylene, R 10 :ethylene, R 11 :-CH2(CH-)CH2-, m3: the sum of formula (3-1) is 20, n3: 0)

[0395] 9G: Polyethylene glycol #400 dimethacrylate (In formula (2-1), R 4 :Methyl, R 5 :ethylene, R 6 : ethylene, m2:9, n2:0)

[0396] 14G: Polyethylene glycol #600 dimethacrylate (In formula (2-1), R 4 :Methyl, R 5 :ethylene, R 6 : ethylene, m2:14, n2:0)

[0397] All of the above are manufactured by Shin-Nakamura Chemical Co., Ltd.

[0398] MEMA-4000: (Polyethylene glycol #4000 dimethacrylate (In formula (2-1), R 4 :Methyl, R 5 :ethylene, R 6: ethylene, m2:90, n2:0), manufactured by Toho Chemical Co., Ltd.

[0399] PEGDA-4000: (polyethylene glycol diacrylate; in formula (2-1), R 4 : hydrogen atom, R 5 :ethylene, R 6 : ethylene, m2:90, n2:0), manufactured by Techno Chemical Co., Ltd.

[0400] Li·FSI stands for lithium bis(fluorosulfonyl)imide.

[0401] 2. Composition of using the polymer electrolyte disclosed herein as a positive electrode active material binder

[0402] [Example 35]

[0403] (Preparation of negative electrode)

[0404] A 20 mm x 30 mm, 60 μm thick lithium foil (manufactured by Honjo Metal Co., Ltd.) was laminated onto a 20 mm x 30 mm, 20 μm thick copper foil, leaving a 10 mm non-laminated end on one side, and then pressed to prepare a negative electrode. The total thickness of the negative electrode was 70 μm. A 5 mm wide nickel-plated copper tab was attached to the non-laminated end on one side of the negative electrode.

[0405] (Solid Electrolyte)

[0406] A 20 mm x 20 mm, 0.18 mm thick sheet of LICGC (manufactured by Ohara Inc.) was used.

[0407] (Preparation of positive electrode)

[0408] A total of 100 parts by mass of lithium cobalt oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 18 parts by mass of the electrolyte solution (60% solid content) from Example 1 as an active material binder and 5 parts by mass of Denka Black Li-100 (manufactured by Denka Corporation) as a conductive auxiliary material, and 40 parts by mass of N-methylpyrrolidone were added, mixed and stirred. The resulting slurry was then applied to a 15 mm × 25 mm, 20 μm thick rolled aluminum foil, leaving a 10 mm non-coated end on one side, and then dried at 100 ° C for 30 min. The membrane surface was then irradiated with 7000 mJ / cm by using a high-pressure mercury UV irradiation device (trade name: Handy 1000, manufactured by Mario Network Co., Ltd.)2 The film was cured by irradiating with UV light with a cumulative light amount of . After curing, it was pressed to obtain a positive electrode with a thickness of 80 μm. An aluminum tab with a width of 5 mm was joined to the non-coated end of one side of the positive electrode.

[0409] (Preparation of a Secondary Battery Using a Polymer Electrolyte as a Binder for a Positive Electrode Active Material)

[0410] The positive electrode with a polymer electrolyte as an active material binder was vacuum dried at 80 ° C for 48 h. Then, the polymer electrolyte membrane was placed in an argon-substituted glove box (temperature 25 ° C, dew point -70 ° C) and stacked in the order of positive electrode / solid electrolyte / negative electrode. The stack was sandwiched between aluminum laminate films and vacuum packed to obtain a secondary battery using the polymer electrolyte of the present disclosure as a positive electrode active material binder according to Example 35.

[0411] [Examples 36 to 39]

[0412] Secondary batteries according to Examples 36 to 39 were prepared in the same manner as in Example 35, except that the electrolyte solution (polymer electrolyte) was changed as shown in Table 7. Evaluation results such as rate characteristics are shown in Table 7.

[0413] 3. Composition of using the polymer electrolyte disclosed herein as the main electrolyte, positive electrode active material binder and negative electrode active material binder

[0414] [Example 40]

[0415] (Preparation of negative electrode)

[0416] A total of 100 parts by mass of graphite powder (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 20 parts by mass of the electrolyte solution (60% solid content) from Example 1 as an active material binder and 5 parts by mass of Denka Black Li-100 (manufactured by Denka Corporation) as a conductive auxiliary material, and 80 parts by mass of N-methylpyrrolidone were added, mixed and stirred. The resulting slurry was then applied to a 20 mm × 30 mm, 20 μm thick copper foil, leaving a 10 mm non-coated end on one side, and then dried at 100 ° C for 30 min. The membrane surface was then irradiated with 8000 mJ / cm by using a high-pressure mercury UV irradiation device (trade name: Handy 1000, manufactured by Mario Network Co., Ltd.) 2The film was cured by irradiating it with UV light with an accumulated light intensity of 100 μm. After curing, it was pressed to obtain a negative electrode with a thickness of 80 μm. Negative electrode active material-uncoated sections (not coated with negative electrode active material) were provided at both ends. A 5 mm wide nickel-plated copper collector tab was bonded to one of the negative electrode active material-uncoated sections.

[0417] (Preparation of positive electrode)

[0418] A total of 100 parts by mass of lithium cobaltate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 18 parts by mass of the electrolyte solution (60% solid content) from Example 1 as an active material binder and 5 parts by mass of Denka Black Li-100 (manufactured by Denka Corporation) as a conductive auxiliary material, and 40 parts by mass of N-methylpyrrolidone were added, mixed and stirred. The resulting slurry was then coated onto a 20 μm thick rolled aluminum foil and dried at 60 ° C for 30 min. Then, the membrane surface was irradiated with 7000 mJ / cm by using a high-pressure mercury UV irradiation device (trade name: Handy 1000, manufactured by Mario Network Co., Ltd.) 2 The film was cured by irradiating it with UV light using a cumulative light intensity of 100 μm. After curing, it was pressed to obtain a positive electrode with a thickness of 80 μm. Positive electrode active material-uncoated sections (not coated with positive electrode active material) were provided at both ends, and a 5 mm wide aluminum current collector tab was bonded to one of the positive electrode active material-uncoated sections.

[0419] (Formation of Polymer Electrolyte Layer)

[0420] The electrolyte solution of Example 1 was applied to the obtained positive electrode using a bar coater, and then air-dried at 23° C. for 10 minutes, and then dried at 60° C. for 30 minutes. Then, the membrane surface was irradiated with a high-pressure mercury UV irradiation device (trade name: Handy1000, manufactured by Mario Network Co., Ltd.) at a concentration of 5000 mJ / cm 2 The film was cured by irradiating with UV light with a cumulative light amount of 100 μm. The thickness of the film after curing was 60 μm.

[0421] (Preparation of a Secondary Battery Using a Polymer Electrolyte as a Main Electrolyte, a Positive Electrode Active Material Binder, and a Negative Electrode Active Material Binder)

[0422] The positive electrode and negative electrode coated with the polymer electrolyte were vacuum dried at 80 ° C for 48h. Then, the polymer electrolyte membrane was placed in an argon-substituted glove box (temperature 25 ° C, dew point -70 ° C), and a polyimide sheet punched into a window frame shape was attached to cover the peripheral portion of the positive electrode surface to form a short circuit prevention layer. Next, the polymer electrolyte layer of the positive electrode coated with the polymer electrolyte was stacked in a manner corresponding to the active material layer of the negative electrode. The stack was sandwiched between aluminum laminate films and vacuum packed to obtain a secondary battery according to Example 40 in which the polymer electrolyte of the present disclosure was used as the main electrolyte, positive electrode active material binder, and negative electrode active material binder.

[0423] [Examples 41 to 44]

[0424] Secondary batteries according to Examples 41 to 44 were prepared in the same manner as in Example 40, except that the electrolyte solution (polymer electrolyte) was changed as shown in Table 7. The evaluation results of rate characteristics and the like are shown in Table 7.

[0425] <Comparative Example>

[0426] [Comparative Example 1]

[0427] As materials of the polymer electrolyte, the following materials were mixed and stirred.

[0428] - Polyether monomethacrylate NK-Ester M-40G (manufactured by Shin-Nakamura Chemical Co., Ltd.): 70 parts by mass

[0429] -Polyether dimethacrylate 4G (manufactured by Shin-Nakamura Chemical Co., Ltd.): 30 parts by mass

[0430] -Lithium bis(trifluoromethanesulfonyl)imide (manufactured by Kishida Chemical Co., Ltd.): 5.0 parts by mass

[0431] - Initiator Omnirad 184 (manufactured by IGM RESINS BV): 2.0 parts by mass

[0432] Next, methyl ethyl ketone was added so as to have a total solid content ratio of 60% by mass, and the mixture was mixed with a motor stirrer to prepare an electrolyte solution.

[0433] A polymer electrolyte and a secondary battery of Comparative Example 1 were manufactured in the same manner as in Example 1.

[0434] [Comparative Examples 2 to 6]

[0435] Polymer electrolytes and secondary batteries of Comparative Examples 2 to 6 were prepared in the same manner as in Example 1 except that the types and amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compound, and supporting electrolyte were changed as shown in Table 4.

[0436] The secondary batteries of Comparative Examples 1 to 6 were constructed using a polymer electrolyte as the main electrolyte. Table 6 shows the evaluation results of rate characteristics and the like.

[0437] [Table 4]

[0438] Table 4

[0439]

[0440] The structures of the materials used in the polymerization are as follows.

[0441] M-40G: Methoxytetraethylene glycol methacrylate (In formula (1-1), R 1 :Methyl, R 2 :ethylene, R 3 : methyl, m1:3, n1:0)

[0442] 4G: Polyethylene glycol #200 dimethacrylate (In formula (2-1), R 4 :Methyl, R 5 :ethylene, R 6 : ethylene, m2:4, n2:0)

[0443] APG-400: Polypropylene glycol #400 diacrylate (In formula (2-1), R 4 : hydrogen atom, R 5 :propylene, R 6 :propylene, m2:0, n2:7)

[0444] AM-90G, AM-130G and A-600 are as described above.

[0445] All of the above are manufactured by Shin-Nakamura Chemical Co., Ltd.

[0446] PA-500: Hydroxypolypropylene glycol monoacrylate (In formula (1-1), R 1 : hydrogen atom, R 2 :propylene, R 3 : hydroxyl, m1: 0, n1: 5), manufactured by Toho Chemical Co., Ltd.

[0447] [Comparative Example 7]

[0448] A secondary battery according to Comparative Example 7 was manufactured in the same manner as in Example 35, except that the positive electrode active material binder was 7 parts by mass of Kureha KH Polymer L#1120 (manufactured by Kureha Co., Ltd.).

[0449] [Comparative Examples 8 to 10]

[0450] Secondary batteries according to Comparative Examples 8 to 10 were manufactured in the same manner as in Example 35, except that the polymer electrolyte used was changed as shown in Table 8.

[0451] Secondary batteries according to Comparative Examples 7 to 10 were constructed using a polymer electrolyte as a positive electrode active material binder. Table 8 shows the evaluation results of rate characteristics and the like.

[0452] [Comparative Examples 11 to 14]

[0453] Secondary batteries according to Comparative Examples 11 to 14 were manufactured in the same manner as in Example 40, except that the polymer electrolyte used was changed as shown in Table 8.

[0454] Secondary batteries according to Comparative Examples 11 to 14 were constructed using polymer electrolytes as a positive electrode active material binder, a main electrolyte, and a negative electrode active material binder. Table 8 shows the evaluation results of rate characteristics and the like.

[0455] The obtained polymer electrolytes and secondary batteries according to Examples 2 to 44 and Comparative Examples 1 to 14 were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 5, 6, 7, and 8.

[0456] [Table 5]

[0457] Table 5

[0458]

[0459] In Tables 5 and 6, Mpo% is the ratio of the average number of added moles Mpo to the average number of added moles Meo.

[0460] [Table 6]

[0461] Table 6

[0462]

[0463] The polymer electrolytes according to Examples 1 to 34 have a structure of formula (1), at least one of the structures of formulas (2) and (3), and a structure of formula (4) in the polymer structure, and have a volume swelling ratio of 40% to 120%. As a result, these polymer electrolytes exhibit high ionic conductivity at both 25°C and 5°C. In addition, secondary batteries using the polymer electrolytes according to Examples 1 to 34 as the main electrolyte have both high rate characteristics and high impact resistance at high temperatures.

[0464] In addition, Examples 7, 8, 11, 13, 14, 18 and 19, in which the mass ratio A:B of the content A of the structure of formula (1) to the content B of the structure of formula (2) in the polymer structure is 70:30 to 98:2, m1+n1 in formula (1-1) is 14 to 58, and m2+n2 in formula (2-1) is 14 to 58, show particularly high ionic conductivity and the rate characteristics of the secondary battery are also good.

[0465] At the same time, the polymer electrolytes of Comparative Example 1 which does not have the structure of formula (4) in the polymer structure, Comparative Examples 2 and 6 which do not have the structure of formula (1), and Comparative Example 3 which has a volume swelling ratio of less than 40% show low ionic conductivity and very poor rate characteristics of secondary batteries.

[0466] Furthermore, the secondary batteries using the polymer electrolytes of Comparative Examples 4 and 5 having a volume swelling ratio greater than 120% or having no three-dimensional crosslinking showed a significant decrease in impact resistance at high temperatures.

[0467] [Table 7]

[0468] Table 7

[0469]

[0470] [Table 8]

[0471] Table 8

[0472]

[0473] The secondary batteries according to Examples 35 to 39 in which the polymer electrolyte of the present invention is used as a positive electrode active material binder and the secondary batteries according to Examples 40 to 44 in which the polymer electrolyte is used as a positive electrode active material binder, a main electrolyte and a negative electrode active material binder have high rate characteristics and high impact resistance at high temperatures, just like the case of using a polymer electrolyte as the main electrolyte.

[0474] Meanwhile, the secondary batteries according to Comparative Examples 8 and 11, which did not have the structure of Formula (4) in the polymer structure, had poor rate characteristics, the secondary batteries according to Comparative Examples 9 and 10, which did not have the structure of Formula (1), had poor rate characteristics, and the secondary battery according to Comparative Example 12, which had a volume swelling ratio of less than 40%, had poor rate characteristics. In addition, the secondary batteries according to Comparative Examples 13 and 14, which had a volume swelling ratio of more than 120% or did not have three-dimensional crosslinking, showed a significant decrease in impact resistance at high temperatures.

[0475] The present disclosure is not limited to the above embodiments, and various modifications and changes can be made without departing from the spirit and scope of the present disclosure. Therefore, the following claims are intended to publicly disclose the scope of the present disclosure.

[0476] This application claims priority based on Japanese Patent Application No. 2022-207165 filed on December 23, 2022, the entire contents of which are incorporated herein by reference.

Claims

1. A polymer electrolyte comprising a polymer having: The structure represented by the following formula (1); At least one structure selected from the group consisting of a structure represented by the following formula (2) and a structure represented by the following formula (3); and The structure represented by the following formula (4) The polymer electrolyte further comprises a lithium salt, and The volume swelling rate of the polymer electrolyte measured by the methyl ethyl ketone immersion method is 40% to 120%. In formula (1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a straight or branched alkylene group having 1 to 6 carbon atoms, R 3 represents an alkyl group having 1 to 6 carbon atoms, In formula (2), R 4 Each independently represents a hydrogen atom or a methyl group, R 5 and R 6 each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms, In formula (3), R 7 Each independently represents a hydrogen atom or a methyl group, R 8 、R 9 and R 10 Each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms, R 11 represents a trivalent organic group having 1 to 6 carbon atoms, A1, B1, D1, D2 and D3 in formulas (1) to (3) are each independently a linking group having at least an ethylene oxide structure represented by -CH2CH2-O-, In formula (4), R 12 represents a hydrogen atom or a methyl group, R 13 Represents a divalent linking group, R 14 、R 15 and R 16 Each independently represents an alkyl group having 1 to 8 carbon atoms, X - Indicates anion. 2 . The polymer electrolyte according to claim 1 , wherein in the polymer, the average number of added moles Meo of the ethylene oxide structure per 1 mole of the (meth)acryloyl residue is 2.5 moles or more. 3 . The polymer electrolyte according to claim 1 , wherein each of A1, B1, D1, D2, and D3 independently further has a propylene oxide structure represented by —CH 2 CH(CH 3 )—O—.

4. The polymer electrolyte according to claim 3, wherein the average number of added moles Mpo of the propylene oxide structure relative to 1 mole of the (meth)acryloyl residue in the polymer is 5% to 25% of the average number of added moles Meo of the ethylene oxide structure relative to 1 mole of the (meth)acryloyl residue in the polymer.

5. The polymer electrolyte according to any one of claims 1 to 4, wherein the mass-based content of the structure represented by the formula (1) in the polymer contained in the polymer electrolyte is represented by A and the mass-based total content of the structure represented by the formula (2) and the structure represented by the formula (3) is represented by B, and the mass ratio A:B is 70:30 to 98:

2.

6. The polymer electrolyte according to any one of claims 1 to 5, wherein The structure represented by the formula (1) is a structure represented by the following formula (1-1), The structure represented by the formula (2) is a structure represented by the following formula (2-1), and The structure represented by the formula (3) is a structure represented by the following formula (3-1): In formula (1-1), R 1 represents a hydrogen atom or a methyl group, R 2 represents a straight or branched alkylene group having 1 to 6 carbon atoms, R 3 represents an alkyl group having 1 to 6 carbon atoms, m1 and n1 are average addition mole numbers, m1 is an integer greater than or equal to 1, and n1 is an integer greater than or equal to 0, the arrangement of the ethylene oxide structure represented by -CH2-CH2-O- and the propylene oxide structure represented by -CH2-CH(CH3)-O- may be a block copolymer or a random copolymer, In formula (2-1), R 4 Each independently represents a hydrogen atom or a methyl group, R 5 and R 6 each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms, m2 and n2 are average addition mole numbers, m2 represents an integer greater than or equal to 1, and n2 represents an integer greater than or equal to 0, the arrangement of the ethylene oxide structure represented by -CH2-CH2-O- and the propylene oxide structure represented by -CH2-CH(CH3)-O- may be a block copolymer or a random copolymer, and the chain sandwiched between the two -COO- may further include a diol structure having 1 to 6 carbon atoms, In formula (3-1), R 7 Each independently represents a hydrogen atom or a methyl group, R 8 、R 9 and R 10 Each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms, R 11 represents a trivalent organic group having 1 to 6 carbon atoms, m3 and n3 are the average number of added moles, m3 each independently represents an integer greater than 1, and n3 each independently represents an integer greater than 0, the arrangement of the ethylene oxide structure represented by -CH2-CH2-O- and the propylene oxide structure represented by -CH2-CH(CH3)-O- may be a block copolymer or a random copolymer, sandwiched between -COO- and R 11 The chain between them may further include a diol structure having 1 to 6 carbon atoms.

7. The polymer electrolyte according to claim 6, wherein m1+n1 in the formula (1-1) is 14 to 58, and m2+n2 in the formula (2-1) and / or m3+n3 in the formula (3-1) are 14 to 58.

8. The polymer electrolyte according to claim 6 or 7, wherein The m1:n1 ratio in the formula (1-1) is 80:20 to 95:5, and The ratio of m2:n2 in the formula (2-1) and / or the ratio of m3:n3 in the formula (3-1) is 80:20 to 95:

5.

9. The polymer electrolyte according to any one of claims 1 to 8, wherein the polymer electrolyte is a dry polymer electrolyte.

10. A secondary battery comprising a positive electrode, a main electrolyte and a negative electrode, wherein At least one selected from the group consisting of a positive electrode, a main electrolyte, and a negative electrode includes the polymer electrolyte according to any one of claims 1 to 9.

11. A secondary battery comprising a positive electrode, a main electrolyte and a negative electrode, wherein The secondary battery satisfies at least any one of the following (i) to (iii): (i) the positive electrode comprises a positive electrode active material and a positive electrode active material binder for fixing the positive electrode active material, and the positive electrode active material binder is a polymer electrolyte according to any one of claims 1 to 9; (ii) the host electrolyte is a polymer electrolyte according to any one of claims 1 to 9; and (iii) The negative electrode includes a negative electrode active material and a negative electrode active material binder that fixes the negative electrode active material, and the negative electrode active material binder is the polymer electrolyte according to any one of claims 1 to 9.

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