TW201938607A - Separator for nonaqueous electrolytic battery and production method therefor - Google Patents

Abstract

The present invention pertains to a separator that is for a nonaqueous electrolytic battery and that comprises a porous film formed of an ethylene-vinyl alcohol copolymer, wherein in the porous film, the proportion of the volume of pores having a pore diameter in the range of 0.1-1 [mu]m with respect to the volume of pores having a pore diameter in the range of 0.01-10 [mu]m is 80% or more in a pore distribution as measured by mercury intrusion.

Description

Separation film for non-aqueous electrolyte battery and manufacturing method thereof

The present invention relates to a separator for a nonaqueous electrolyte battery, a method for manufacturing the same, and a nonaqueous electrolyte battery using the separator for a nonaqueous electrolyte battery.

In recent years, various non-aqueous electrolyte batteries have been developed with the popularization of mobile terminals such as mobile phones, notebook personal computers, and pad-type information terminal devices, or electric vehicles and hybrid vehicles. Non-aqueous electrolyte batteries, such as lithium ion secondary batteries, differ in form, capacity, and performance depending on their use, but generally speaking, a positive electrode and a negative electrode are provided via a separator _6, LiBF _4, LiTFSI (lithium (bistrifluoromethylsulfonyl (PEI))), LiFSI (lithium (bis-fluoro (PEI) sulfonyl)) is a lithium salt is dissolved in diethyl carbonate or the like extending from the organic liquid The structure in which the electrolytic solution is stored in a container together.

In the non-aqueous electrolyte battery having the structure described above, compared to water-based batteries, temperature rise due to external heat, smoke generation, fire, and cracks due to overcharging, internal short circuits, or external short circuits are more likely to occur. The danger requires high safety. In the past, in order to ensure safety, most of the separators constituting non-aqueous electrolyte batteries were composed of porous membranes (porous membranes). When the temperature inside the battery increased, the flow of ions or ions was blocked by blocking the holes , Has the so-called shutdown function. As such a separator, a porous film made of a polyolefin resin is widely used. For example, for the purpose of improving safety, it is proposed to provide a coating layer containing filler particles and a binder, and to use a polyolefin resin. The formed porous separator (Patent Document 1). Further, as a porous film, a porous film made of an ethylene-vinyl alcohol copolymer produced by a wet coagulation method is known (Patent Document 2), and an ethylene-vinyl alcohol copolymer porous film has been proposed as a separator. Use (Patent Document 3).
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2007-280911
[Patent Document 2] Japanese Patent Laid-Open No. 49-113859
[Patent Document 3] Japanese Patent Laid-Open No. 56-49157

[Problems to be Solved by the Invention]

However, in an isolation film provided with a coating layer containing filler particles or a binder on a porous film as described in Patent Document 1, the internal resistance of an electrical component increases, and output characteristics tend to decrease. As the charge and discharge cycle progresses, The capacity is drastically reduced, and there is a problem that the cycle life is shortened. In addition, since it is necessary to provide a coating layer on the porous membrane, there are also problems of an increase in production cost or a decrease in productivity. On the other hand, in the method described in Patent Document 2, since it is difficult to sufficiently control the pores or the porosity, the pores of the obtained porous membrane tend to become non-uniform, and the pore diameter tends to be relatively small. Therefore, when such a porous film is used as a separator of a non-aqueous electrolyte battery, the performance of the battery as a constituent member of the battery may not be satisfactory because the liquid permeability of the electrolytic solution is reduced and the internal resistance is increased. Furthermore, the ethylene-vinyl alcohol copolymer porous membrane described in Patent Document 3 is insufficient in mechanical strength as a separator of a non-aqueous electrolyte battery or performance as a constituent member of a battery, and is required to control porosity or pore size. Inorganic powder is used, so some steps such as partial recovery are not necessary, and there is a problem of lack of productivity.

Therefore, an object of the present invention is to provide a separator for a non-aqueous electrolyte battery, which has high safety and sufficient control of pores. When used as a separator for a non-aqueous electrolyte battery, the internal resistance is low, and the battery can be highly efficient and high Capacity, etc. improve battery characteristics. It is another object of the present invention to provide a method for manufacturing a separator for a non-aqueous electrolyte battery, which is capable of easily controlling pores or porosity and efficiently manufacturing a separator for a non-aqueous electrolyte battery capable of improving battery characteristics.

[Means for solving problems]

The present inventors conducted an intensive review in order to solve the above-mentioned problems, and as a result, have reached the present invention. That is, this invention provides the following suitable aspects.
[1] A separator for a non-aqueous electrolyte battery, which is made of a porous film made of an ethylene-vinyl alcohol copolymer. In the porous film, the fineness measured by the mercury intrusion method is determined. The ratio of the pore volume in the pore size range of 0.1 to 1 μm to the pore volume in the range of 0.01 to 10 μm is 80% or more.
[2] The separator for a non-aqueous electrolyte battery according to the above [1], wherein the porosity of the porous film is 20% or more.
[3] The separator for a non-aqueous electrolyte battery according to the above [1] or [2], wherein the endothermic peak heat from the crystalline melting of the porous film and the ethylene from the porous film are measured by a differential scanning calorimeter- The ratio of the endothermic peak heat of the crystal melting of the vinyl alcohol copolymer (the endothermic peak heat of the porous membrane / the endothermic peak heat of the ethylene-vinyl alcohol copolymer) is 1.10 to 3.50.
[4] The separator for a non-aqueous electrolyte battery according to any one of the above [1] to [3], wherein the porous film is a flat film having a thickness of 1 μm or more and less than 50 μm.
[5] The separator for a non-aqueous electrolyte battery according to any one of the above [1] to [4], wherein the ethylene content of the ethylene-vinyl alcohol copolymer is 20 to 60 mol%, and the degree of saponification is 80 More than%.
[6] The separator for a non-aqueous electrolyte battery according to any one of the above [1] to [5], wherein the ethylene-vinyl alcohol copolymer has a crosslinked structure.
[7] A method for manufacturing a separator for a non-aqueous electrolyte battery, comprising the step of wet-coagulating a solution containing an ethylene-vinyl alcohol copolymer and a solvent,
The step of wet coagulation includes immersion in a coagulation solution for 1 second to 30 minutes, and the solution containing the ethylene-vinyl alcohol copolymer and a solvent, and the solution can be applied to a substrate.
The absolute value of the difference between the temperature of the solution and the temperature of the coagulation solution is 35 ° C. or lower, and the solvent constituting the solution is a mixed solvent containing water and alcohol.
[8] The production method according to the aforementioned [7], wherein the temperature of the coagulation liquid is 10 to 70 ° C.
[9] The production method according to the aforementioned [7] or [8], wherein the coagulation liquid contains 50% by mass or more of water relative to the total mass of the coagulation liquid.
[10] A non-aqueous electrolyte battery including the separator for a non-aqueous electrolyte battery according to any one of the above [1] to [6].

[Effect of the invention]

According to the present invention, a separator for a non-aqueous electrolyte battery can be provided, which has high safety and adequate control of pores. When used as a separator for a non-aqueous electrolyte battery, it has low internal resistance, high efficiency, and high battery capacity. It improves battery characteristics. In addition, the present invention can provide a method for manufacturing a separator for a non-aqueous electrolyte battery, which is easy to control pores or porosity, and can efficiently manufacture a separator for a non-aqueous electrolyte battery capable of improving battery characteristics.

[Mode for Carrying Out the Invention]

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited thereto.

The separator for a non-aqueous electrolyte battery of the present invention (hereinafter, also referred to as the "separator of the present invention") is made of a porous film composed of an ethylene-vinyl alcohol copolymer to isolate the non-aqueous electrolyte. The positive electrode and the negative electrode in a battery pass through or hold the electrolytic solution, and have an ion transport property that allows ions to pass between the positive electrode and the negative electrode.

In the present invention, as the ethylene-vinyl alcohol copolymer used to form the release film, for example, one obtained by saponifying an ethylene-vinyl ester copolymer such as an ethylene-vinyl acetate copolymer can be used. In the present invention, the ethylene content (ethylene to mass) of the ethylene-vinyl alcohol copolymer is preferably from 20 to 60 mol%. When the ethylene content is above the lower limit, the water resistance of the obtained porous film can be improved. When the ethylene content is below the above upper limit, the ethylene-vinyl alcohol copolymer is moderately hydrophilic, and therefore it is easy. Processed into a porous membrane. In the present invention, the ethylene content of the ethylene-vinyl alcohol copolymer is more preferably 25 mol% or more, particularly preferably 30 mol% or more, and more preferably 55 mol% or less, and even more preferably 50 mol. %the following.

The saponification degree of the ethylene-vinyl alcohol copolymer is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more. When the degree of saponification is at least the above lower limit value, the moldability is good, and a separator having high mechanical strength can be obtained. The upper limit of the degree of saponification is not particularly limited, but it is 100 mol% or less, and it is particularly preferable to use a completely saponification (that is, a degree of saponification of 100 mol%). In addition, as long as the degree of saponification is 99 mol% or more, it is judged that it is completely saponified. In one embodiment of the present invention, as the ethylene-vinyl alcohol copolymer used to form the release film of the present invention, the ethylene content is preferably 20 to 60 mol%, and the saponification degree is preferably 80 mol. %the above.

The copolymerization morphology of the ethylene-vinyl alcohol copolymer is not particularly limited, and may be any of a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer.

In the present invention, the ethylene-vinyl alcohol copolymer may contain a structure derived from a monomer copolymerizable with these units other than the ethylene unit and the vinyl alcohol unit, as long as the effects of the present invention are not impaired. Unit (hereinafter, also referred to as "other structural unit"). Examples of such other structural units include α-olefins such as propylene, isobutylene, α-octene, and α-dodecene; acrylic acid, methacrylic acid, methyl methacrylate, crotonic acid, maleic acid, Unsaturated acids such as itaconic acid or their anhydrides, salts, or mono- or dialkyl esters; nitriles such as acrylonitrile, methacrylonitrile; and other amines such as acrylamide and methacrylamide; Olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid or the like; alkyl vinyl ethers, vinyl ketones, N-vinyl pyrrolidone, vinyl chloride, vinylidene Vinyl chloride, etc. When the ethylene-vinyl alcohol-based copolymer contains a structural unit derived from another monomer, its content is preferably 15 mol% or less, and more preferably 10 mol% or less.

In the present invention, the ethylene-vinyl alcohol copolymer is preferably one having a crosslinked structure. If the ethylene-vinyl alcohol copolymer has a crosslinked structure, the mechanical strength of the porous membrane (separation membrane) composed of the copolymer can be increased, and the liquid retention property can also be improved. The cross-linked structure is a structure derived from a compound (hereinafter, also referred to as a "cross-linking agent") having at least two functional groups capable of reacting with a hydroxyl group contained in a vinyl alcohol unit in an ethylene-vinyl alcohol copolymer. The ethylene-vinyl alcohol copolymer can be reacted with a crosslinking agent to be introduced as a cross-linked structure formed by using a hydroxyl group in a vinyl alcohol unit as a crosslinking point. In the present invention, examples of the crosslinking agent capable of introducing a crosslinking structure into an ethylene-vinyl alcohol copolymer include oxalic acid, malonic acid, methylmalonic acid, succinic acid, methylsuccinic acid, and dicarboxylic acid. Methyl succinic acid, 2,3-dimethyl succinic acid, glutamic acid, 3-methyl glutamic acid, adipic acid, 3-methyl adipic acid, pimelic acid, sebacic acid, azelaic acid Saturated dicarboxylic acids such as tartaric acid, cyclohexanedicarboxylic acid, etc .; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, pentenedioic acid, aconitic acid, etc .; p-benzene Aromatic dicarboxylic acids such as dicarboxylic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid; tricarboxylic acids such as citric acid; polycarboxylic acids such as polyacrylic acid, polymethacrylic acid, and polymaleic acid; Organic cross-linking agents such as diisocyanates and dialdehydes, and inorganic cross-linking agents such as boron compounds. Among them, citric acid, boric acid, and glyoxylic acid are preferred from the viewpoint of maintaining a moderate pore structure and introducing a crosslinked structure. These systems can be used alone or in combination of two or more.

In the ethylene-vinyl alcohol copolymer, the content of the structural unit derived from the crosslinking agent introduced into the above-mentioned crosslinking structure is preferably 0.01 mol% or more, more preferably 0.1 mol% or more, and preferably 15 mol. % Or less, more preferably 10 mol% or less. If the content of the structural unit derived from the cross-linking agent introduced into the cross-linking structure is within the above range, a moderate cross-linking structure is formed between the molecules of the ethylene-vinyl alcohol copolymer and the cross-linking agent, and the obtained release film is maintained. The liquid permeability of the electrolyte can improve mechanical strength or liquid retention.

The introduction of the cross-linked structure into the ethylene-vinyl alcohol copolymer can be achieved by bringing the ethylene-vinyl alcohol copolymer with the above-mentioned polymer before or after the film forming step for forming a porous film from the copolymer. The crosslinking agent proceeds. At this time, the addition amount of the cross-linking agent is preferably 0.001 to 5% by mass, more preferably 0.01 to 3% by mass, and even more preferably 0.05 to 2% by mass relative to the total mass of the ethylene-vinyl alcohol copolymer. In addition, the introduction of the cross-linked structure into the ethylene-vinyl alcohol copolymer may be performed by adding a cross-linking agent to the coagulation liquid. In this case, the ethylene-vinyl alcohol copolymer is used to form the separator of the present invention. The total weight of a solution of a substance and a solvent (hereinafter, also referred to as a "mixed liquid for forming a porous membrane"), the addition amount of the crosslinking agent is preferably 0.001 to 5 mass%, more preferably 0.01 to 4 mass%, and particularly preferably It is 0.05 to 3% by mass. In addition, whether or not a crosslinked structure is introduced can be confirmed by, for example, whether a peak of a crosslinking agent from the obtained film is observed by infrared spectrometry or elemental analysis.

In this invention, the manufacturing method of an ethylene-vinyl alcohol copolymer is not specifically limited, It can be prepared by a conventional method.

The separator of the present invention is made of a porous film, and the porous film is made of an ethylene-vinyl alcohol copolymer. The content of the ethylene-vinyl alcohol copolymer in the separator (porous film) of the present invention is generally 90% by mass or more, preferably 95% by mass or more, and more preferably 97% by mass or more, with respect to the total mass of the separator. The separation film system may be formed of a porous film substantially composed of an ethylene-vinyl alcohol copolymer (that is, the content of the ethylene-vinyl alcohol copolymer is 100% by mass relative to the total mass of the separation film).

In the porous membrane constituting the separator of the present invention, the pore volume in the pore size range of 0.1 to 1 μm in the pore size distribution measured by the mercury intrusion method is relative to the pore volume in the range of 0.01 to 10 μm. The proportion is above 80%. The porous membrane constituting the separation membrane of the present invention is made of a porous membrane showing sharp pore distribution as described above. Since it has uniform pores, it can form a uniform current distribution during charge and discharge, and dendritic crystals are not easy to precipitate. By using such a separator, a nonaqueous electrolyte battery can be obtained, which is less prone to internal short circuits, has excellent safety, has a long battery life, and has excellent battery characteristics. In contrast, if the ratio of the pore volume in the pore size range of 0.1 to 1 μm to the pore volume in the range of 0.01 to 10 μm in the pore size distribution measured by the mercury intrusion method is less than 80%, then The pores become non-uniform and tend to have poor performance as a separator for non-aqueous electrolyte batteries. In the present invention, the ratio of the pore volume in the pore diameter range of 0.1 to 1 μm to the pore volume in the pore diameter range of 0.01 to 10 μm in the pore distribution is preferably 82% or more, and more preferably 85% or more. , Especially better than 88%. The upper limit of the ratio of the pore volume is not particularly limited, but it is usually 99% or less, and preferably 98% or less. In addition, the above-mentioned measurement of the pore distribution by the mercury intrusion method can be performed in accordance with a method described in Examples described later.

The porosity of the porous film constituting the separation film of the present invention is preferably 20% or more, more preferably 25% or more, particularly preferably 30% or more, and particularly preferably 40% or more. When the porosity is equal to or more than the above lower limit value, the electrolyte solution is excellent in liquid permeability and ion passage is facilitated, so that resistance can be reduced. The porosity is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less. If the porosity is equal to or less than the above upper limit, the strength of the porous membrane can be increased. Therefore, by using such a separator, a non-aqueous electrolyte battery that is less prone to internal short circuits can be obtained. The porosity can be measured and calculated from the thickness and weight of the film and the density of the polymer. The detailed measurement and calculation methods are described in Examples described later.

The average pore diameter of the porous film constituting the separator of the present invention is preferably 0.01 μm or more, more preferably 0.1 μm or more, particularly preferably 0.5 μm or more, and preferably 4 μm or less, and more preferably 3.5 μm or less. It is particularly preferably 3 μm or less. When the average pore diameter is equal to or more than the above-mentioned lower limit value, sufficient liquid permeability to the electrolytic solution can be secured, and resistance can be reduced. In addition, if the average pore diameter is equal to or less than the above-mentioned upper limit value, it is possible to prevent the electrodes from coming into contact with each other, and to obtain a nonaqueous electrolyte battery in which an internal short circuit is unlikely to occur. The average pore diameter is a value of pores on the surface of a separator (porous film) obtained by observation with an electron microscope (SEM).

The shape of the pores of the porous membrane is not particularly limited, and examples thereof include a monolithic shape, a honeycomb shape, a disc shape, and a polygonal plate shape. Among them, a monolithic shape is preferable, which includes a shape of a skeleton and a void having a three-dimensional mesh structure that is not easily short-circuited while having a high electrolyte transportability, and each has a short-circuit resistance.

In the separator of the present invention, the ratio of the endothermic peak heat from the crystal melting of the porous film measured by a differential scanning calorimeter to the endothermic peak heat from the crystal melting of the ethylene-vinyl alcohol-based copolymer constituting the porous film. (The endothermic peak heat of the porous film / the endothermic peak heat of the ethylene-vinyl alcohol copolymer) is preferably 1.10 to 3.50, more preferably 1.20 to 3.00, and even more preferably 1.30 to 2.00. The higher the ratio of the above-mentioned endothermic peak heat of the porous film to the ethylene-vinyl alcohol-based copolymer constituting the porous film, it means that a porous film having higher crystallinity is obtained compared with the ethylene-vinyl alcohol-based copolymer as a raw material. . When the ethylene content of the ethylene-vinyl alcohol copolymer used as the raw material is the same, the higher the ratio of the endothermic peak, the higher the crystallinity. Generally, if the ratio of the endothermic peak heat is within the above range, the porous film will crystallize When it is used as a separator of a non-aqueous electrolyte battery, the ion passing system can easily proceed smoothly and the conductivity can be improved. Thereby, resistance can be reduced, and a highly efficient nonaqueous electrolyte battery can be obtained. In addition, the "endothermic peak heat from crystal melting" means the endothermic heat of the second cycle measured by a differential scanning calorimeter when the porous membrane or the ethylene-vinyl alcohol copolymer constituting the porous membrane is heated. The peak absorbs heat. The detailed measurement method is described in Examples described later.

The porous membrane system constituting the separator of the present invention is not particularly limited, but is preferably a flat membrane. The thickness is preferably 1 μm or more and less than 50 μm, more preferably 5 μm or more, even more preferably 10 μm or more, still more preferably 40 μm or less, and even more preferably 35 μm or less. When the thickness of the porous film is equal to or more than the above-mentioned lower limit, the strength of the porous film is sufficiently high, and an isolation film that suppresses the occurrence of cracks and is unlikely to cause a short circuit can be obtained. When the thickness of the porous film is equal to or less than the above-mentioned upper limit value, the liquid permeability of the electrolytic solution is good, and the battery resistance can be reduced.

The separator of the present invention can be produced, for example, by a method including a step of wet-setting a solution containing an ethylene-vinyl alcohol copolymer and a solvent,
The step of wet coagulation includes immersion in a coagulation solution for 1 second to 30 minutes, and the solution containing the ethylene-vinyl alcohol copolymer and a solvent, and the solution can be applied to a substrate.
The absolute value of the difference between the temperature of the solution and the temperature of the coagulation solution is 35 ° C. or lower, and the solvent constituting the solution is a mixed solvent containing water and alcohol.
Therefore, the present invention is also directed to a manufacturing method (hereinafter, also referred to as the "manufacturing method of the present invention"), which is a method for manufacturing a separator for a non-aqueous electrolyte battery, which includes an ethylene-vinyl alcohol-based copolymer and The step of wet coagulation of the solvent solution,
The step of wet coagulation includes immersion in a coagulation solution for 1 second to 30 minutes, and the solution containing the ethylene-vinyl alcohol copolymer and a solvent, and the solution can be applied to a substrate.
The absolute value of the difference between the temperature of the solution and the temperature of the coagulation solution is 35 ° C. or lower, and the solvent constituting the solution is a mixed solvent containing water and alcohol.

The production method of the present invention includes a step of wet-coagulating a solution (mixed liquid for forming a porous film) containing an ethylene-vinyl alcohol copolymer and a solvent (hereinafter, also referred to as a "coagulation step"). As the ethylene-vinyl alcohol-based copolymer constituting the mixed liquid for forming a porous film, the same as the ethylene-vinyl alcohol-based copolymer described previously regarding the separator of the present invention can be used.

The solvent used for the mixed liquid for forming a porous film is a mixed solvent containing water and an alcohol from the viewpoint of the solubility of the ethylene-vinyl alcohol copolymer. Examples of alcohols that can be mixed with water in the mixed solvent include methanol, ethanol, butanol, isopropanol, 1-propanol, 1-butanol, and ethylene glycol. These systems can be used alone or in combination of two or more. Among these, from the viewpoint of the solubility of the ethylene-vinyl alcohol copolymer and the formation of pores, the solvent used for the mixed liquid for forming a porous film is preferably water and a solvent selected from the group consisting of methanol, ethanol, isopropanol, and 1- A mixed solvent of one or more alcohols in a group of propanol.

In a mixed solvent containing water and alcohol, the mixing ratio of water to alcohol (water / alcohol) is preferably 20/80 to 70/30, and more preferably 25/75 to 65/35. By using a mixed solvent containing water and alcohol at a ratio in the above range, it is possible to easily prepare a mixed solution for forming a porous film, which contains an ethylene-vinyl alcohol-based copolymer having a solid content concentration suitable for the formation of the porous film. In the production method of the present invention, as long as the mixed solvent used for the mixed liquid for forming a porous film is capable of dissolving an ethylene-vinyl alcohol copolymer, it may contain a small amount of water and a solvent other than alcohol, but it is preferably water. And alcohol mixed solvent.

The solid content concentration of the ethylene-vinyl alcohol copolymer in the mixed liquid for forming a porous film is preferably 3 to 50% by mass, and more preferably 5 to 45% by mass. When the solid content concentration of the ethylene-vinyl alcohol copolymer is within the above range, the handleability of the porous film forming mixed solution is good, and it is easy to form a porous film by wet coagulation.

The mixed solution for forming a porous film may contain a crosslinking agent for introducing a crosslinking structure into the ethylene-vinyl alcohol copolymer constituting the separator of the present invention. At this time, the addition amount of the cross-linking agent is preferably 0.001 to 5% by mass, more preferably 0.01 to 3% by mass, and even more preferably 0.05 to 2% by mass relative to the total mass of the ethylene-vinyl alcohol copolymer.

The mixed liquid system for forming a porous film may contain a polymer compound (copolymer) other than an ethylene-vinyl alcohol copolymer, an antioxidant, an ultraviolet absorber, a lubricant, and the like, as long as the effect of the present invention is not impaired. Additives such as defoamers and anti-blocking agents, such as inorganic fine powder or organic matter. At this time, the content of the components other than the ethylene-vinyl alcohol-based copolymer is usually 10% by mass or less, and preferably 5% by mass or less, relative to the solid content of the mixed solution for forming a porous film. In addition, the solid content of the mixed liquid for porous film formation means the total amount of the component after removing a solvent from the mixed liquid for porous film formation.

The mixed liquid system for forming a porous film can be made by mixing and stirring other components such as an ethylene-vinyl alcohol copolymer and, if necessary, a crosslinking agent or an additive, with a mixed solvent containing water and an alcohol to copolymerize the ethylene-vinyl alcohol system. Derived from the material. A wet film can be obtained by immersing the obtained mixed liquid for forming a porous film in a coagulation liquid and coagulating it.

The impregnation of the mixed liquid for forming a porous film in a coagulation liquid is not particularly limited as long as a wet film having a desired shape and film thickness is obtained after coagulation. For example, the mixed liquid for forming a porous film can be applied to a substrate The mixed solution for forming a porous film is immersed in the coagulation solution together with the substrate, and the mixed solution for forming a porous film may be directly charged into the coagulation solution through a slit. Specific examples of a method for applying the porous film-forming mixed solution to a substrate include a doctor blade method, a dipping method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a dipping method, and a brush coating method. And other methods. In addition, as a method of directly pouring the mixed liquid for forming a porous film into a coagulation liquid, for example, extrusion by a T-die method, an inflation method, or the like can be used.

Examples of the substrate to which the mixed liquid for forming a porous film can be applied include polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), and polyethylene (PE). , Glass, etc.

The coagulation liquid is not particularly limited as long as it is a solution capable of coagulating a mixed liquid for forming a porous film, and examples thereof include water, a mixed solution of water, and an organic solvent. Examples of the organic solvent that can be mixed with water include alcohols such as methanol, ethanol, isopropanol, and 1-propanol, and ketones such as acetone and methyl ethyl ketone. These systems can be used alone or in combination of two or more. In view of the high coagulation ability of the mixed liquid for forming a porous film, and easy to obtain uniform pores, the coagulated liquid is preferably water or a mixed solution of water and an organic solvent. Furthermore, it is easy to prepare or discard the solvent. More preferred is water or a mixed solution of water and alcohol.

When a cross-linking structure is introduced into the ethylene-vinyl alcohol-based copolymer constituting the release film of the present invention, a cross-linking agent may be added to the coagulation solution. At this time, the addition amount of the cross-linking agent is preferably 0.001 to 5% by mass, more preferably 0.01 to 4% by mass, and even more preferably, relative to the total weight of the porous film forming mixed solution used to form the separator of the present invention. It is 0.05 to 3% by mass.

The content of water in the coagulation liquid is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more relative to the total mass of the coagulation solution. In other words, when the coagulation liquid is made of water and an organic solvent (preferably an alcohol), the content of the organic solvent in the coagulation liquid is preferably less than 50% by mass, and more preferably less than 40% with respect to the total mass of the coagulation liquid. Mass%, particularly preferably less than 30% by mass. The upper limit of the content of water in the coagulation liquid is not particularly limited, and may be made of only water (that is, 100% by mass). The higher the water content, the faster the coagulation rate, so the more the water content in the coagulation solution is, the better, but in the continuous production of the separation membrane, due to the alcohol brought in from the mixed solution for porous film formation, Existing, so the upper limit of water content is usually about 98% by mass.

In the production method of the present invention, the absolute value of the difference between the temperature of the mixed liquid for forming a porous film and the temperature of the coagulation liquid is 35 ° C or lower. By setting the difference between the temperature of the mixed solution for porous film formation and the temperature of the coagulation solution to an absolute value of 35 ° C. or less, the pores or porosity of the obtained porous film can be effectively and easily controlled, and it is possible to obtain a porous film suitable for A porous membrane having a fine pore diameter and a uniform pore in a separator for a water electrolyte battery. On the other hand, if the difference between the temperature of the porous film forming mixed liquid and the temperature of the coagulation liquid becomes too large, the coagulation speed of the ethylene-vinyl alcohol copolymer is faster than the pore formation speed, and the copolymer cannot be sufficiently coagulated. Ground pores are formed, making it difficult to obtain a desired pore size. In addition, the production method of the present invention can control the pores or porosity by adjusting the temperature of the mixed liquid for forming a porous film and the temperature of the coagulation liquid. Since no further steps or complicated steps for controlling the pores or porosity are required. Steps, so it has high productivity and has the advantage of reducing production costs. In addition, by reducing the difference between the temperature of the mixed liquid for forming a porous film and the temperature of the coagulation liquid, under a condition in the above-mentioned temperature range, a coagulation step is performed, so that the obtained porous film and the ethylene constituting the porous film can be easily separated. -The ratio of the endothermic peak heat of crystalline melting of the vinyl alcohol copolymer is controlled within a desired range. In the manufacturing method of the present invention, the absolute value of the difference between the temperature of the mixed liquid for forming a porous film and the temperature of the coagulation liquid is preferably 20 ° C or lower, more preferably 15 ° C or lower, and even more preferably 12 ° C or lower. The lower limit of the difference between the temperature of the porous film forming mixed liquid and the temperature of the coagulating liquid is not particularly limited, and is usually about 10 ° C. The temperature of the mixed liquid for porous film forming and the temperature of the coagulating liquid may be the same (ie, 0 ° C) . In addition, in the present invention, the temperature of the mixed liquid for forming a porous film means the temperature of the mixed liquid when the mixed liquid for forming a porous film is put into a coagulation liquid, and it is immersed in a substrate immediately after being applied to a substrate or the like. In the case of a coagulation liquid, the temperature at the time of applying the mixed liquid for forming a porous film can be regarded as the temperature of the mixed liquid for forming a porous film.

The temperature of the coagulation liquid is preferably 10 to 70 ° C, more preferably 15 ° C or more, particularly preferably 20 ° C or more, particularly preferably 30 ° C or more, very preferably more than 30 ° C, and more preferably 65 ° C or less. When the temperature of the coagulation liquid is within the above range, a film and pores are formed by coagulation of the ethylene-vinyl alcohol copolymer in a well-balanced manner, so that a porous film having desired pores and porosity can be obtained. In addition, by reducing the difference between the temperature of the mixed liquid for forming a porous film and the temperature of the coagulation liquid, under a condition in the above-mentioned temperature range, a coagulation step is performed, so that the obtained porous film and the ethylene constituting the porous film can be easily separated. -The ratio of the endothermic peak heat of crystalline melting of the vinyl alcohol copolymer is controlled within a desired range. On the other hand, if the temperature of the coagulation liquid is too low, phase separation is performed before pore formation, so that it is difficult to perform sufficient pore formation, and it is difficult to obtain a porous film having a desired pore diameter or porosity. Further, if the temperature of the coagulation liquid is too high, spinodal decomposition does not sufficiently occur, and it becomes difficult to form a porous film.

The temperature of the mixed liquid for forming a porous film is preferably 20 to 90 ° C, and more preferably 30 to 80 ° C. When the temperature of the mixed solution for forming a porous film is within the above range, when immersed in the coagulation liquid, the film formation and pore formation are performed by coagulation of the ethylene-vinyl alcohol copolymer in good balance. In addition, by reducing the difference between the temperature of the mixed liquid for forming a porous film and the temperature of the coagulation liquid, under a condition in the above-mentioned temperature range, a coagulation step is performed, so that the obtained porous film and the ethylene constituting the porous film can be easily separated. -The ratio of the endothermic peak heat of crystalline melting of the vinyl alcohol copolymer is controlled within a desired range.

In the manufacturing method of the present invention, the immersion time of the mixed liquid for forming a porous film in the coagulation liquid is 1 second to 30 minutes, preferably 3 seconds or more, more preferably 5 seconds or more, and preferably 25 minutes or less. It is more preferably 20 minutes or less. If the immersion time is too short, the ethylene-vinyl alcohol copolymer is not sufficiently solidified, and it is difficult to obtain a pore having a desired pore diameter. In addition, if the immersion time is too long, excessive swelling occurs in the coagulation liquid, and in extreme cases, the porosity decreases, not only the desired pores are not obtained, but also productivity decreases.

In the manufacturing method of the present invention, the wet film obtained by the coagulation step may be subjected to a drying treatment for removing a solvent. The drying method is not particularly limited. For example, natural drying can be performed; warm air, hot air, and low humidity air can be used for drying; heating and drying; reduced pressure / vacuum drying; infrared, far infrared, and electron rays. Drying and these combinations are performed. From the viewpoint of not disturbing the pores and voids formed in the solidification step and improving the production efficiency, aeration drying is preferred. The drying conditions can be based on the type of solvent used or the amount of solvent contained in the wet film, within a range that does not damage the obtained porous film (for example, the occurrence of cracks caused by stress concentration), so as to be as fast as possible The method of removing the solvent is appropriately determined. For example, the drying temperature is usually 10 to 150 ° C, preferably 25 to 110 ° C, and the drying time is usually about 1 to 90 minutes.

In order to improve the smoothness of the porous film, a rolling treatment may be applied to the porous film after the solvent is removed. Examples of the rolling method include a method such as die pressing or rolling.

The non-aqueous electrolyte separation membrane obtained by the manufacturing method of the present invention is made of a porous membrane showing sharp pore distribution. Since it has uniform pores, it can form a uniform current distribution during charging and discharging. It is difficult to precipitate like crystals. By using such a separator, a non-aqueous electrolyte battery can be obtained. The internal short circuit is not easy to occur, the safety is excellent, the battery life is long, and the battery characteristics are excellent. Therefore, the present invention also targets a nonaqueous electrolyte battery including the separator for a nonaqueous electrolyte battery of the present invention.

The non-aqueous electrolyte battery of the present invention includes the separator of the present invention. Examples of the non-aqueous electrolyte battery include a lithium-ion battery, a sodium-ion battery, a lithium-sulfur battery, an all-solid-state battery, and a lithium-ion capacitor.

The non-aqueous electrolyte battery of the present invention generally includes a positive electrode, a negative electrode, and an electrolyte in addition to the separator of the present invention. The non-aqueous electrolyte battery system of the present invention can be manufactured using well-known materials and technologies.

As the negative electrode, a negative electrode generally used in a non-aqueous electrolyte battery such as a lithium ion secondary battery can be used without particular limitation. For example, as the negative electrode active material, graphite, hard carbon, Si-based oxide, or the like can be used. In addition, the negative electrode active material and conductive additives such as metal powder, conductive polymer, acetylene black, carbon black, and SBR, NBR, acrylic rubber, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinylidene can be used. Binders such as vinyl fluoride and polyvinyl alcohol are mixed in water or a solvent having a boiling point of 100 ° C to 300 ° C (for example, N-methyl-2-pyrrolidone, etc.) under normal pressure to prepare a slurry for negative electrodes. This negative electrode slurry is applied to a negative electrode current collector such as a copper foil, and the solvent is dried to form a negative electrode.

As the positive electrode, a positive electrode generally used in a non-aqueous electrolyte battery such as a lithium ion secondary battery can be used without particular limitation. For example, as the positive electrode active material, TiS ₂ , TiS ₃ , amorphous MoS ₃ , Cu ₂ V ₂ O ₃ , amorphous V ₂ OP ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O _{13 can be used.} And other transition metal oxides or lithium-containing composite metal oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , and LiMn ₂ O ₄ . In addition, the positive electrode active material and the conductive auxiliary agent shown in the negative electrode can be bonded to SBR, NBR, acrylic rubber, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinylidene fluoride, polyvinyl alcohol, and the like. The agent is mixed with water or a solvent having a boiling point of 100 ° C. to 300 ° C. under normal pressure to prepare a slurry for a positive electrode. The slurry for a positive electrode is applied to a positive electrode current collector such as aluminum, and the solvent is dried. And become positive.

As the electrolytic solution in the non-aqueous electrolyte battery of the present invention, an electrolytic solution obtained by dissolving an electrolyte in a solvent can be used. As long as the electrolytic solution is used in ordinary non-aqueous electrolyte batteries such as lithium ion secondary batteries, it may be in a liquid state or a gel state. It can be appropriately selected and used according to the type of the negative electrode active material and the positive electrode active material. Functional person of battery. As specific electrolytes, for example, conventional lithium salts can be used, and examples thereof include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiB ₁₀ Cl ₁₀ , and LiAlC. _l4 , LiCl, LiBr, LiB (C ₂ H ₅ ) ₄ , CF ₃ SO ₃ Li, CH ₃ SO ₃ Li, LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, low grade Aliphatic lithium carboxylate and the like.

The solvent (electrolytic solution solvent) for dissolving such an electrolyte is not particularly limited. Specific examples include carbonates such as propylene carbonate, ethylene carbonate, butyl carbonate, dimethyl carbonate, and diethyl carbonate; and lactones such as γ-butyllactone; Ethers such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, and the like ; 1,3-dioxolane, 4-methyl-1,3-dioxolane and other oxolane; nitrogen compounds such as acetonitrile or nitromethane; methyl formate, methyl acetate, Organic acid esters such as ethyl acetate, butyl acetate, methyl propionate, and ethyl propionate; inorganic acid esters such as triethyl phosphate, dimethyl carbonate, and diethyl carbonate; diethylene glycol di Methyl ethers; triethylene glycol dimethyl ethers; cyclobutanes; 3-methyl-2-oxazolidinones, etc .; oxazolidinones; 1,3-propanelactone, 1,4- Sulfolactones such as butyrolactone and naphthalene-1,8-sultone can be used alone or in combination of two or more. When a gel-like electrolytic solution is used, as the gelling agent, a nitrile polymer, an acrylic polymer, a fluorine polymer, an alkylene oxide polymer, or the like can be added.

In particular, as a binder used in the negative electrode or the positive electrode, a polymer compound is used, which has a copolymer containing vinyl alcohol, vinyl acetal, and / or vinyl ester, which is the same material as the separator of the present invention. Productivity is improved by preventing the electrode position from being separated from the separator of the present invention or preventing the active material from falling off. Therefore, as the adhesive, it is more preferable to use the same material as the release film of the present invention. On the other hand, from the viewpoint of achieving a balance between ease and productivity improvement, the use of SBR-based emulsions is also one of the appropriate aspects.

The method for manufacturing the non-aqueous electrolyte battery of the present invention is not particularly limited, and it can be manufactured according to a conventional method. For example, a method in which a negative electrode and a positive electrode are laminated through the separator of the present invention, and wound and folded according to the shape of the battery, and the method is put into a battery container, and an electrolytic solution is injected to seal the method. In the present invention, the shape of the non-aqueous electrolyte battery may be any of a well-known coin type, button type, sheet type, cylindrical type, square type, flat type, and the like.

The non-aqueous electrolyte battery of the present invention containing the separator of the present invention as a constituent member has high battery safety, does not easily increase internal resistance, and has excellent battery characteristics such as high battery capacity. The non-aqueous electrolyte battery system of the present invention can be applied to various applications. For example, the non-aqueous electrolyte battery system can be used as a mobile terminal that requires miniaturization, thinness, weight reduction, and high performance, or charge and discharge characteristics that require high capacity and large current. Battery used in large equipment such as electric cars.

[Example]

Hereinafter, the present invention will be specifically described by examples, but these are not intended to limit the scope of the present invention.

Example 1
(1) Preparation of a mixed liquid for forming a porous film An ethylene-vinyl alcohol copolymer powder (K105, manufactured by Kurary, E105B) having an ethylene content of 44 mol% was dissolved in water and mixed with 1-propanol at 70 ° C for 3 hours. In the solvent (water / 1-propanol = 35/65 volume ratio), a mixed solution for forming a porous film having a solid content concentration of 10% by mass was prepared.

(2) Preparation of separator Using a bar coater (T101, manufactured by Matsuo Industry Co., Ltd.), apply the above-mentioned obtained mixed liquid for forming a porous film (temperature of mixed liquid for forming a porous film: 50 ° C) and leave it After the substrate made of a glass plate on a water platform was immersed, the mixed liquid for forming a porous film was immersed in a water bath at 40 ° C. for 10 minutes with the glass plate substrate to solidify. Next, a wet film made of an ethylene-vinyl alcohol copolymer was taken out, peeled from the substrate, and air-dried, and then dried at 100 ° C for 1 hour to obtain a release film made of a porous film. The film thickness of the obtained porous film was 28 μm.

(3) Measurement of physical properties of the separator (porous film) The pore distribution, pore size, porosity, liquid absorption, crystallinity, tensile strength, and membrane resistance of the obtained separator (porous film) were measured according to the following Method measurement and calculation. The results are shown in Table 1.

＜ pore distribution ＞
The pore volume distribution was calculated by the mercury intrusion method under the following conditions. Based on the measured pore distribution, the ratio of the pore volume in the range of pore diameters of 0.1 to 1 μm to the pore volume in the range of pore diameters of 0.01 to 10 μm was calculated.
Measurement conditions:
Measuring device: QUANTACHROME instrument poremaster 33-P-GT manufactured by Nippon Union
Mercury contact angle 130.00∘, surface tension 485.00erg / cm ²
Pressure range: 12.2kPa ～ 123MPa
Cell box volume: 1cc

＜ Calculation of void ratio ＞
The porosity of the porous membrane is measured by measuring the thickness and mass of a sample punched to a specified size (φ17 mm), and calculating it according to the following formula.
Void ratio = {1- (theoretical volume of the separator / apparent volume of the separator)} × 100
Theoretical volume of the separator = (mass of the separator) / (theoretical density)
Apparent volume of the separator = (thickness) × (area of the separator)

＜ Liquid absorption ＞
100 ml of a mixed solvent (EC / EMC = 3/7) of ethyl carbonate (EC) and ethyl methyl carbonate (EMC) was placed in a container. The separator was cut to a length of 10 mm and a width of 60 mm. The width of the front end was immersed in the mixed solvent of 1 mm. After 1 minute, the mixed solvent absorbed by the capillary phenomenon was measured from the liquid surface. Lifting height (aspiration height). The evaluation was performed ten times on one sample, and the average value was taken as the electrolyte liquid absorption height.

＜ pore diameter ＞
The diameters of 100 openings observed by scanning electron microscope photography were averaged and calculated.

<Crystalliness>
The ratio of the endothermic peak heat from the crystalline melting of the porous membrane to the endothermic peak heat from the crystalline melting of the ethylene-vinyl alcohol-based copolymer constituting the porous film (Peak heat), under the following conditions, using a differential scanning calorimeter (DSC) to measure the porous membrane and the ethylene-vinyl alcohol copolymer, respectively, and the obtained values of the second cycle peak are regarded as derived from the porous membrane The endothermic peak heat of crystal melting and the endothermic peak heat from crystal melting of the ethylene-vinyl alcohol-based copolymer constituting the porous film were calculated.
Measurement conditions:
Measuring device: TA Instruments Japan Inc. DISCOVERY DSC / DSC25
Sample weight 2mg
Heating rate: 10 ℃ / min. Scanning temperature: 0 ～ 200 ℃

<Tensile strength>
The tensile strength is a test piece based on JIS K 7162-1B and calculated by a tensile tester under the following conditions.
Measurement conditions:
Measuring device: Autograph AG5000B, manufactured by Shimadzu Corporation Temperature: 25 ° C
Distance between chucks: 70mm
Test speed: 500mm / min Test piece: Dumbbell type (width of test section 10mm)

＜ Film resistance ＞
Cut out the dimensions of 4.8 × 4.5cm and 4.9 × 4.7cm from the aluminum foil with a thickness of 20μm. After attaching the lead head, sandwich these 2 pieces of aluminum foil into an insulation film (porous membrane) cut into a size of 5.1 × 5.0cm. )1. The release film sandwiched by the aluminum foil was placed in the aluminum laminated laminated module so that the lead head was exposed out of the aluminum laminated module, and then the electrolytic solution (ethylene carbonate (EC) was sealed under reduced pressure. / Ethyl methyl carbonate (EMC) / dimethyl carbonate (DMC) = 1/1/1, 1.0 M LiPF ₆ ) 350 μl to obtain a battery for measuring membrane resistance.
A battery for measuring film resistance was produced by the same method as above except that the number of the separators sandwiched by the aluminum foil was set to two and three. The prepared battery was placed in a 25 ° C constant temperature bath, and the resistance of the battery was measured by an AC impedance method at an amplitude of 10 mV and a frequency of 100 kHz. The measured resistance value of the battery was fabricated with respect to the number of separators in the battery, and the fabrication was linearly approximated to obtain the slope. This slope was multiplied by 4.8 × 4.5 cm of the electrode area to determine the film resistance (Ωcm ² ) per one sheet of the separator.

(4) Evaluation of battery characteristics of separator The battery characteristics of a non-aqueous electrolyte battery using the obtained separator were evaluated according to the following method.

＜ Production of battery negative electrode ＞
Solid content of SBR-based emulsified aqueous solution (TRD2001, manufactured by JSR Co., Ltd.) (48.3% by mass) with respect to 96 parts by mass of artificial graphite (FSN-1, manufactured by Shanshan, China) as an active material for the negative electrode 2 1 part by mass of solid content of CMC-Na (Sodium Carboxymethyl Cellulose; Cellogen BSH-6, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., 10% by mass) as a thickener, and a conductive additive (conductivity imparting agent) 1 part by mass of solid content of Super-P (manufactured by TIMCAL Co., Ltd.) was put into a dedicated container, and kneaded with a planetary agitator (ARE-250, manufactured by THINKY Co., Ltd.) to prepare an electrode coating slurry. The composition ratio of the active material and the binder in the slurry is expressed by solid content, graphite powder: conductive additive: SBR: CMC-Na = 96: 1: 2: 1 (mass ratio).

＜ Production of battery negative electrode ＞
Using a bar coater (T101, manufactured by Matsuo Industry Co., Ltd.), the obtained electrode coating slurry was applied to a copper foil (CST8G, manufactured by Fukuda Metal Foil Powder Co., Ltd.) of a current collector, After drying at a temperature (24.5 ° C) for the next time, a roll press (manufactured by Baoquan Co., Ltd.) was used to perform a rolling treatment. Then, it was punched into a battery electrode (φ14 mm), and then subjected to secondary drying at 140 ° C for 3 hours under reduced pressure to obtain a coated electrode for a coin battery.

＜ Production of coin-type battery ＞
The coated electrode for a coin-type battery obtained above was transferred to a glove box (manufactured by Miwa Manufacturing Co., Ltd.) under an argon atmosphere. A metal lithium foil (thickness: 0.2 mm, φ16 mm) was used for the positive electrode. In addition, the porous membrane obtained as described above was used as the separator. The electrolytic solution used was ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in which lithium hexafluoride phosphate (LiPF ₆ ) was added. (VC) mixed solvent system (1M-LiPF ₆ , EC / EMC = 3/7% by volume, VC2% by mass) was injected to make a coin-type battery (type 2032).

＜ Resistance measurement ＞
Using the coin-type battery produced as described above, an AC impedance measurement was performed using an impedance measuring device (potentiometer / galvanostat (SI1287, manufactured by SOLARTRON) and a frequency response analyzer (FRA, manufactured by SOLARTRON)). The coin-type battery was placed in a constant temperature bath at 25 ° C and -20 ° C, and the impedance pattern of the test battery was measured by an AC impedance method at a frequency of 0.01 to 10 ⁶ Hz and a voltage amplitude of 10 mV. For the measured impedance spectrum, on the complex plane (Cole-Cole mapping) specified by the component axis (Z-axis, imaginary axis) of the resistance and the component axis (Z-axis, imaginary axis) of the capacity, the When the line graph including the arc-shaped portion is shown, the diameter of the arc-shaped portion is taken as the interface resistance (Rin) with the separator, and the component axis (Z axis, imaginary axis) of the capacity when the component axis (Z axis, imaginary axis) of the capacity is 0 ( The values of the Z axis and the real axis) are taken as the solution resistance (Rsol), and the conductivity at 25 ° C and -20 ° C are calculated, respectively. The results are shown in Table 1.

2.Example 2
A separator was produced in the same manner as in Example 1 except that an ethylene-vinyl alcohol copolymer powder (KURARY, F101B) with an ethylene content of 32 mol% was used, and the temperature of the coagulation liquid was set to 30 ° C. Each physical property was evaluated. . A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 1.

3. Example 3
Except using 27 mol% ethylene-vinyl alcohol copolymer powder (L171B, manufactured by Kurary), and dissolving it in a mixed solvent of water / 1-propanol = 45/55 (volume ratio) at 70 ° C for 3 hours A separator was produced in the same manner as in Example 2, and each physical property was evaluated by the same method as in Example 1. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 1.

4.Example 4
A separator was produced in the same manner as in Example 1 except that an ethylene-vinyl alcohol copolymer powder (K156, manufactured by G156B) containing 48 mol% of ethylene was used, and each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 1.

5.Example 5
A separator was produced in the same manner as in Example 1 except that a mixed solvent of water / 1-propanol = 40/60 (volume ratio) was used as a mixed solvent for the mixed liquid for forming a porous film. Each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 1.

6. Example 6
A separator was produced in the same manner as in Example 1 except that the mixed solvent for the mixed liquid for forming a porous film was a mixed solvent of water / 1-propanol = 45/55 (volume ratio), and each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 1.

7.Example 7
A separator was produced in the same manner as in Example 1 except that the temperature of the coagulation liquid was set to 15 ° C, and each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 1.

8.Example 8
A separator was produced in the same manner as in Example 1 except that the immersion time was set to 1 minute, and each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 1.

9. Comparative Example 1
A separator was produced in the same manner as in Example 1 except that the immersion time was 60 minutes, and each physical property was evaluated. In addition, coin-type batteries were produced and resistance measurement was performed in the same manner as in Example 1. However, three out of 20 short-circuited battery systems occurred, and battery production stability was poor.

10. Comparative Example 2
A separator was produced in the same manner as in Example 1 except that the temperature of the coagulation liquid was changed to 5 ° C, and various physical properties were evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 1.

11. Comparative Example 3
A coin-type battery was produced in the same manner as in Example 1 except that a commercially available polypropylene-based separator (Celgard # 2400, film thickness: 25 μm, pore diameter 0.043 μm, manufactured by POLYPORE) was used as the separator. . The resistance was measured by the same method as in Example 1. The results are shown in Table 1.

12.Example 15
A separator was produced in the same manner as in Example 1 except that the thickness of the film was set to 53 μm, and each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 1.

13.Example 9
A separator was prepared in the same manner as in Example 1 except that citric acid (Wako Pure Chemical Industries, Ltd.) was added to the coagulation liquid in an amount of 0.05% by mass, and each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 2. In addition, in Examples 9 to 12, it was confirmed by infrared spectroscopy that a structure derived from citric acid, oxalic acid, or terephthalic acid was present in the obtained separation film.

14.Example 10
A separator was produced in the same manner as in Example 9 except that the amount of citric acid was 0.10% by mass, and each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 2.

15.Example 11
A separator was produced in the same manner as in Example 9 except that the amount of citric acid was 1.00% by mass, and each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 2.

16.Example 12
A separator was produced in the same manner as in Example 10 except that an ethylene-vinyl alcohol copolymer powder (KURARY, F101B) with an ethylene content of 32 mol% was used, and each physical property was evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 2.

17.Example 13
A release film was produced in the same manner as in Example 10 except that oxalic acid (Wako Pure Chemical Industries, Ltd.) was used instead of citric acid, and various physical properties were evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 2.

18.Example 14
A release film was produced in the same manner as in Example 10, except that terephthalic acid (Wako Pure Chemical Industries, Ltd.) was used instead of citric acid, and various physical properties were evaluated. A coin-type battery was produced in the same manner as in Example 1 and resistance measurement was performed. The results are shown in Table 2.

Compared with the general-purpose separator shown in Comparative Example 3, the separators according to Examples 1 to 15 according to the present invention show that the conductivity at low temperatures useful as a battery is increased. In addition, the liquid absorbing time is high, and the electrolyte permeation time after the liquid injection is sufficiently shortened, which can shorten the curing time after the liquid electrolyte injection, which is the main factor that reduces the productivity in the battery assembly step. In the manufacturing process of the separator, and in the manufacturing process of the battery, productivity can be improved. On the other hand, in the separator produced by Comparative Example 1 having a long immersion time, the pore volume in the pore size range of 0.1 to 1 μm in the pore distribution is relative to the pore volume in the range of 0.01 to 10 μm. The ratio is less than 80%, the pore size is large, the porosity is also high, and the number of short-circuited batteries is increased. On the other hand, in the separator made in Comparative Example 2 in which the temperature of the coagulation solution is low and the temperature difference from the mixed solution for forming a porous film is large, the porosity and the pore diameter become small, and the separator has high resistance. membrane. In addition, in the separators of Examples 9 to 14 using an ethylene-vinyl alcohol-based copolymer having a crosslinked structure, it was confirmed that the tensile strength and the liquid absorbency were improved.

Claims (10)

A separator for a non-aqueous electrolyte battery, which is made of a porous film made of an ethylene-vinyl alcohol copolymer. In the porous film, a pore distribution is measured by a mercury intrusion method. The ratio of the pore volume in the range of pore diameters of 0.1 to 1 μm to the pore volume in the range of pore diameters of 0.01 to 10 μm is 80% or more. The separator for a non-aqueous electrolyte battery according to claim 1, wherein the porosity of the porous film is 20% or more. The separator for a non-aqueous electrolyte battery according to claim 1 or 2, wherein the endothermic peak heat from crystal melting of the porous film and the crystal from the ethylene-vinyl alcohol copolymer constituting the porous film are measured by a differential scanning calorimeter. The ratio of the melting endothermic peak heat (the endothermic peak heat of the porous membrane / the endothermic peak heat of the ethylene-vinyl alcohol copolymer) is 1.10 to 3.50. The separator for a non-aqueous electrolyte battery according to claim 1 or 2, wherein the porous film is a flat film having a thickness of 1 μm or more and less than 50 μm. For example, the non-aqueous electrolyte battery separator according to claim 1 or 2, wherein the ethylene content of the ethylene-vinyl alcohol copolymer is 20 to 60 mol%, and the degree of saponification is 80 mol% or more. The separator for a non-aqueous electrolyte battery according to claim 1 or 2, wherein the ethylene-vinyl alcohol copolymer has a crosslinked structure. A manufacturing method, which is a method for manufacturing a separator for a non-aqueous electrolyte battery, comprising the step of wet-coagulating a solution containing an ethylene-vinyl alcohol copolymer and a solvent, The aforementioned wet coagulation step includes immersing in a coagulation solution for 1 second to 30 minutes, and the solution containing the ethylene-vinyl alcohol copolymer and a solvent, and the solution can be applied to a substrate, The absolute value of the difference between the temperature of the solution and the temperature of the coagulation solution is 35 ° C. or lower, and the solvent constituting the solution is a mixed solvent containing water and alcohol. The manufacturing method according to claim 7, wherein the temperature of the coagulating solution is 10 to 70 ° C. The manufacturing method according to claim 7 or 8, wherein the coagulating liquid contains 50% by mass or more of water relative to the total mass of the coagulating liquid. A non-aqueous electrolyte battery including the separator for a non-aqueous electrolyte battery according to any one of claims 1 to 6.