JP2019133747A - Porous layer for nonaqueous battery, method for manufacturing the same, separator for nonaqueous battery, electrode for nonaqueous battery and nonaqueous battery - Google Patents

Abstract

To provide: a porous layer to be interposed between positive and negative electrodes of a nonaqueous battery, which can suppress an amount of water contents brought into the nonaqueous battery; a manufacturing method thereof; a separator and an electrode, each having the porous layer; and a nonaqueous battery which has the separator or electrode, and which can suppress the worsening in a property by an amount of water contents brought into the inside.SOLUTION: A porous layer for a nonaqueous battery according to the present invention comprises: corpuscles formed by an organic material or inorganic material; and a water-soluble resin. In the porous layer, the content of the corpuscles is 50 mass% or more; an acrylic acid-based polymer containing a constituting unit based on (meth)acrylic acid and a constituting unit based on a (meth)acrylic acid salt is included as the water-soluble resin; and the content of the acrylic acid-based polymer is 0.05-0.45 mass%. The porous layer further comprises a binder component. A nonaqueous battery of the invention comprises a separator or electrode having the porous layer for a nonaqueous battery according to the invention.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a porous layer interposed between a positive electrode and a negative electrode of a nonaqueous battery, which can suppress the amount of moisture brought into the nonaqueous battery, a method for producing the same, and a separator having the porous layer In addition, the present invention relates to a non-aqueous battery that has an electrode, the separator or the electrode, and is capable of suppressing deterioration in characteristics due to moisture brought into the inside.

  A lithium secondary battery, which is a kind of non-aqueous battery, is widely used as a power source for portable devices such as mobile phones and notebook personal computers because of its high energy density. As the performance of portable devices increases, the capacity of lithium secondary batteries tends to increase further, and it is important to ensure safety.

  In current lithium secondary batteries, a polyolefin-based porous film having a thickness of, for example, about 10 to 30 μm is used as a separator interposed between a positive electrode and a negative electrode. In addition, as separator material, the constituent resin of the separator is melted below the thermal runaway temperature of the battery to close the pores, thereby increasing the internal resistance of the battery and improving the safety of the battery in the event of a short circuit. In order to ensure the so-called shutdown effect, polyethylene having a low melting point may be applied.

  By the way, as such a separator, for example, a uniaxially stretched film or a biaxially stretched film is used for increasing the porosity and improving the strength. Since such a separator is supplied as a single film, a certain strength is required in terms of workability and the like, and this is secured by the stretching. However, with such a stretched film, the degree of crystallinity has increased, and the shutdown temperature has increased to a temperature close to the thermal runaway temperature of the battery. Therefore, it can be said that the margin for ensuring the safety of the battery is sufficient. hard.

  In addition, the film is distorted by the stretching, and there is a problem that when it is exposed to a high temperature, shrinkage occurs due to residual stress. The shrinkage temperature is very close to the shutdown temperature. For this reason, when a polyolefin-based porous film separator is used, when the battery temperature reaches the shutdown temperature in the case of abnormal charging, the current must be immediately decreased to prevent the battery temperature from rising. This is because if the pores are not sufficiently closed and the current cannot be reduced immediately, the battery temperature easily rises to the contraction temperature of the separator, and there is a risk of ignition due to an internal short circuit.

  As a technology to prevent such a short circuit due to thermal contraction of the separator and increase the reliability of the battery, a laminated type in which a heat resistant porous layer for improving heat resistance is formed on the surface of a porous resin film containing a thermoplastic resin. It has been proposed to use a separator of US Pat.

  For example, according to the techniques disclosed in Patent Documents 1 and 2, it is possible to provide a non-aqueous battery that is less likely to cause thermal runaway even when abnormally overheated, and that is excellent in safety and reliability.

  Patent Document 3 discloses a copolymer of an N-vinylcarboxylic acid amide having a specific structure and an unsaturated carboxylic acid monomer having a specific structure in a heat-resistant porous layer interposed between a positive electrode and a negative electrode. Used as an organic binder, this porous layer is used for the heat-resistant porous layer of the above-mentioned laminated separator, or formed on the surface of the positive electrode or negative electrode to play the role of a separator, so it has excellent safety It has been proposed to construct a non-aqueous battery.

JP 2008-123996 A JP 2008-210791 A International Publication No. 2015/046126

  By the way, the porous layer comprises a step of applying a coating liquid such as slurry or paste prepared by dispersing fine particles composed of an organic material or an inorganic material in a solvent to the surface of the resin porous membrane or the electrode. In general, the coating solution is made of carboxymethylcellulose (CMC) or the like as a thickener for the purpose of facilitating the adjustment of the thickness of the coated film after coating. It is normal.

  However, since thickeners such as CMC have hygroscopicity, the porous layer formed by applying the coating liquid contains a large amount of moisture. In particular, when using a coating liquid in which the solid content ratio (ratio of components other than the solvent; the same applies hereinafter) is used, it is necessary to increase the amount of thickener added in order to form a good coating film. The water content of the porous layer after formation increases. If a non-aqueous battery is formed using a separator or electrode having a porous layer having a high water content, a large amount of moisture is brought into the non-aqueous battery, causing deterioration of the characteristics of the non-aqueous battery. It becomes.

  The present invention has been made in view of the above-described current problems, and an object of the present invention is a porous layer interposed between a positive electrode and a negative electrode of a nonaqueous battery, Porous layer capable of suppressing the amount of moisture to be brought in and method for producing the same, separator and electrode having the porous layer, and non-aqueous battery having the separator or the electrode and capable of suppressing characteristic deterioration due to moisture brought into the inside Is to provide.

  The porous layer for a nonaqueous battery of the present invention is a porous layer containing fine particles composed of an organic material or an inorganic material and a water-soluble resin, and the content of the fine particles is 50% by mass or more. In addition, the water-soluble resin includes an acrylic acid polymer including a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate, and the content of the acrylic acid polymer is 0.05 to It is 0.45 mass%, and further contains a binder component.

  “(Meth) acrylic acid” means acrylic acid or methacrylic acid.

  The porous layer for a non-aqueous battery of the present invention is an acrylic acid-based material including fine particles composed of an organic material or an inorganic material, a structural unit based on (meth) acrylic acid, and a structural unit based on (meth) acrylate. The coating liquid containing a polymer, a binder component, and a solvent can be produced by the production method of the present invention having a step of applying to a substrate surface and drying.

  The separator for nonaqueous batteries of the present invention is characterized in that the porous layer for nonaqueous batteries of the present invention is integrated with a porous resin sheet.

  Furthermore, the electrode for a nonaqueous battery of the present invention has an electrode mixture layer containing an active material, and has the porous layer for a nonaqueous battery of the present invention on the electrode mixture layer. It is.

  The nonaqueous battery of the present invention includes (a) a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, and the separator is the nonaqueous battery separator of the present invention, or (b) a positive electrode, a negative electrode And at least one of the positive electrode and the negative electrode is the electrode for a non-aqueous battery according to the present invention.

  According to the present invention, a porous layer interposed between a positive electrode and a negative electrode of a non-aqueous battery, which can suppress the amount of moisture brought into the non-aqueous battery, a method for producing the same, and the porous layer It is possible to provide a non-aqueous battery that includes the separator and the electrode, and the separator or the electrode, and that can suppress deterioration in characteristics due to moisture introduced therein.

It is a longitudinal section showing an example of the nonaqueous battery of the present invention typically.

  As described above, a coating liquid (composition containing a solvent such as slurry or paste) for forming a porous layer provided as a heat-resistant layer of a separator or a separator layer interposed between a positive electrode and a negative electrode, particularly an aqueous system In order to adjust the viscosity, a water-soluble resin having a hygroscopic property such as CMC is generally used for the coating liquid, and this increases the amount of moisture brought into the non-aqueous battery. Causing non-aqueous battery characteristics to deteriorate.

  As a result of intensive studies to realize suppression of deterioration in characteristics of nonaqueous batteries due to the above reasons, the present inventors have applied a coating liquid used for forming a porous layer provided in a separator, an electrode, or the like. As the thickener, an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate is adopted. Thereby, since it becomes difficult for moisture to be contained in the porous layer after formation, it is possible to reduce the amount of moisture brought into the non-aqueous battery and to thereby suppress deterioration of characteristics.

  The porous layer for non-aqueous batteries of the present invention (hereinafter simply referred to as “porous layer”) comprises fine particles composed of an organic material or an inorganic material, a structural unit based on (meth) acrylic acid, and (meth) acrylic acid. An acrylic acid polymer containing a structural unit based on a salt and a binder component are included.

  In the porous layer of the present invention, the fine particles composed of an organic material or an inorganic material are caused by lithium dendrites, for example, by filling the voids formed between the fibrous materials described later. In the case where the fine particles are made of a material having a heat-resistant temperature of 150 ° C. or higher and the porous layer is applied as a heat-resistant layer of the separator, It functions as a component that enhances properties. Furthermore, it is possible to provide a shutdown function to the porous layer by forming the fine particles from a heat-meltable resin, for example, a resin having a melting point of 150 ° C. or less.

  In addition, an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate is used as a thickener for a coating liquid for forming a porous layer, It remains in the porous layer after formation. If it is a coating liquid using the acrylic acid polymer as a thickener, it is possible to easily ensure at least a viscosity enough to perform at least a suitable coating operation with a small amount of addition, and to provide a porous layer after formation. Reduces the amount of moisture adsorbed in the quality layer compared to the use of common thickeners such as CMC and water-soluble resins such as sodium polyacrylate that does not contain structural units based on (meth) acrylic acid. be able to.

  The term “including a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate” in the acrylic acid polymer referred to in the present specification forms a molecule of an acrylic acid polymer. As a structural unit, as shown in the following formula (1), one derived from (meth) acrylic acid (one having a carboxyl group as it is), and as shown in the following formula (2), (meth) It means that the carboxyl group of acrylic acid is in the form of a salt. The structural unit in which the carboxyl group of (meth) acrylic acid is converted into a salt is one introduced into the molecule in the form of using a salt of (meth) acrylic acid as a monomer for polymerizing the acrylic acid polymer [ie, The structural unit derived from a salt of (meth) acrylic acid] or a part of the carboxyl group in the polymer obtained by polymerizing (meth) acrylic acid [the structural unit derived from (meth) acrylic acid in the polymer May be introduced by neutralizing a carboxyl group possessed by a part thereof.

In the formula (1), R ¹ is H or CH ₃ .

In the formula (2), R ² is H or CH ₃ , and M is an alkali metal element, NH ₄ or the like.

  Therefore, as an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate used for the porous layer, for example, in a polyacrylic acid part due to an alkali metal, etc. A part of a carboxylate group (—COOH) in a structural unit based on acrylic acid in a polyacrylic acid (polymer) is converted into an alkali metal salt such as a sodium salt [—COOM ′ (M 'Is an alkali metal element)].

  A completely neutralized product of polyacrylic acid (all of the carboxyl groups are converted to alkali metal salts) is easy to absorb water, and a porous layer containing a certain amount of this makes it difficult to reduce the amount of water. In the porous layer (coating liquid for forming it), an acrylic acid polymer (for example, in a polyacrylic acid part) containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate Japanese).

  The acrylic polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate is composed of a structural unit based on (meth) acrylic acid and a structure based on (meth) acrylate. A ternary system containing a constituent unit other than the unit, and containing a constituent unit based on a monomer component such as acrylamide, acrylonitrile, N-vinylacetamide, or the like, depending on the required properties. The above polymer can also be used.

  However, in the acrylic acid polymer, the number of moles of the structural unit based on (meth) acrylic acid [the structural unit represented by the formula (1)] is a, and the structural unit based on (meth) acrylate [the above In order to obtain a suitable thickening amount in a small amount when b is the number of moles of the structural unit represented by formula (2) and c is the number of moles of the other structural units, (meth) acrylic acid and The ratio (molar ratio) of structural units other than the structural units based on the salt, that is, the value represented by c / (a + b + c) is desirably 0.3 or less, and more desirably 0.2 or less. , 0.1 or less is most desirable.

  In addition, the acrylic polymer represented by a partially neutralized product of polyacrylic acid has a “neutralization degree (%) determined by the following formula from the viewpoint of ensuring a better water content reduction effect in the porous layer. ) "Is preferably 70% or less, and more preferably 55% or less. On the other hand, in order to enhance the thickening effect, the neutralization degree of the acrylic acid polymer is preferably 10% or more, and more preferably 30% or more.

  Degree of neutralization = b ÷ (a + b) × 100

  In order to make the acrylic acid-based polymer function as a thickener and to make the coating liquid containing this a certain viscosity or more necessary for coating, in the porous layer formed by drying the coating liquid What is necessary is just to adjust content in the said coating liquid so that it may become 0.05 mass% or more in content, and content of the said acrylic acid type polymer in a porous layer is 0.1 mass % Or more is preferable.

  On the other hand, if the content of the acrylic acid polymer in the porous layer is too large, the viscosity of the coating solution may be too high, and the water content in the formed porous layer will be too large. There is a possibility that the effect of reducing the amount of water due to the use of the acrylic acid polymer is impaired. In order to prevent the above problems, the content in the coating solution may be adjusted so that the content of the acrylic acid polymer in the porous layer is 0.45% by mass or less. The content of the acrylic acid polymer in the layer is preferably 0.3% by mass or less.

  In addition, according to the purpose, the thickener of the coating liquid includes an acrylic acid polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate, and other than the above-mentioned polymer. A water-soluble resin can also be used in combination.

  Examples of the water-soluble resin that can be used in combination with the acrylic acid polymer include polyacrylic acid, sodium polyacrylate, carboxymethylcellulose, and the like.

  However, in order to make it easier to adjust the viscosity of the coating liquid to a suitable range and to ensure a better water content reduction effect in the porous layer, the content of the entire water-soluble resin in the porous layer For example, in the separator including the porous layer, it is desirable to adjust the moisture content measured by the method described later to 1200 ppm or less. Specifically, the content of the entire water-soluble resin including the acrylic acid polymer in the porous layer is preferably 0.5% by mass or less, for example.

  The acrylic acid polymer that functions as a thickener in the coating solution has a low function as a binder, and this alone does not provide sufficient adhesive strength. Therefore, in the present invention, the binder is further added to the porous layer. Ingredients are included.

  As the binder in the porous layer, ethylene-vinyl acetate copolymer (EVA, structural unit derived from vinyl acetate is 20 to 35 mol%), (meth) acrylate polymer ["(meth) acrylate" It is an expression of acrylate and methacrylate collectively. same as below. ], Fluorinated rubber, styrene butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP), polyurethane, poly N-vinylacetamide, polyacrylamide and the like. Thus, in addition to those used in the form of an aqueous emulsion, a water-soluble resin such as polyvinyl alcohol can also be used. One or more of these can be used for the binder.

  The content of the binder in the porous layer is preferably 0.5% by mass or more from the viewpoint of satisfactorily exerting the action of the binder. On the other hand, if the amount of the binder is too large, the content of other components (such as fine particles composed of an organic material or an inorganic material) decreases, and the action of these other components may be reduced. The binder content in the layer is preferably 10% by mass or less.

  The fine particles composed of an organic material or an inorganic material related to the porous layer have an electrical insulating property, are electrochemically stable, and further include a non-aqueous electrolyte described later and a coating solution for forming a porous layer. There is no particular limitation as long as the solvent used in is stable.

  As used herein, “stable to non-aqueous electrolyte” means dissolved in a solvent or chemical composition in a non-aqueous electrolyte (a non-aqueous electrolyte such as a non-aqueous electrolyte used as an electrolyte for a non-aqueous battery). It means that it is difficult to make changes. “Stable in the solvent used in the coating liquid for forming the porous layer” has the same meaning as described above. Furthermore, “electrochemically stable” as used in the present specification means that a chemical change hardly occurs during charging / discharging of the battery.

The fine particles composed of an inorganic material are preferably composed of a material having a heat resistant temperature of 150 ° C. or higher, that is, a material that does not decompose or melt at a temperature of 150 ° C. or lower. Is, for example, oxide fine particles such as iron oxide, SiO ₂ , Al ₂ O ₃ , TiO ₂ , BaTiO ₃ , ZrO ₂ , MgO; nitride fine particles such as aluminum nitride and silicon nitride; calcium fluoride and barium fluoride Poorly soluble ionic crystal particles such as barium sulfate; Covalent crystal particles such as silicon and diamond; Clay particles such as talc and montmorillonite; Boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, Substances derived from mineral resources such as hydrotalcite Man-made; and inorganic fine particles such as.

  In addition, the fine particles composed of an organic material, like the inorganic material, are composed of a material having a heat-resistant temperature of 150 ° C. or higher. Specific examples thereof include polyimide, melamine resin, phenolic resin, and crosslinked polymer. Fine particles of crosslinked polymer such as methyl methacrylate (crosslinked PMMA), crosslinked polystyrene (crosslinked PS), polydivinylbenzene (PDVB), benzoguanamine-formaldehyde condensate; and fine particles of heat resistant polymer such as thermoplastic polyimide. The organic resin (polymer) constituting these organic fine particles is a mixture, modified body, derivative, copolymer (random copolymer, alternating copolymer, block copolymer, graft copolymer) of the materials exemplified above. ) Or a crosslinked product (in the case of the heat-resistant polymer).

  On the other hand, when providing a shutdown function to the porous layer, it is preferable that the fine particles are composed of a heat-meltable resin having a melting point of 150 ° C. or lower so that the battery reaction can be suppressed at a safe temperature. In order to increase the melting point, the melting point of the hot-melt resin is more preferably 140 ° C. or lower. Specific examples of such fine particles include, for example, PE, a copolymerized polyolefin having a structural unit derived from ethylene of 85 mol% or more, or a polyolefin derivative (such as chlorinated polyethylene), a polyolefin wax, a petroleum wax, or a carnauba wax. It is done. Examples of the copolymer polyolefin include an ethylene-vinyl monomer copolymer, more specifically, an ethylene-vinyl acetate copolymer (EVA), an ethylene-methyl acrylate copolymer, or an ethylene-ethyl acrylate copolymer. it can. Moreover, polycycloolefin etc. can also be used.

  However, if the temperature at which the shutdown occurs is too low, there is a risk of hindering normal battery operation. Therefore, the melting point of the heat-meltable resin is preferably 100 ° C. or higher, more preferably 120 ° C. or higher. preferable. The melting point of the resin is a melting temperature measured using a differential scanning calorimeter (DSC) in accordance with JIS K 7121.

  The shutdown function in the porous layer can be evaluated by, for example, an increase in resistance due to the temperature of the model cell. That is, a positive electrode, a negative electrode, and an electrolytic solution are provided, and a porous layer is provided on an electrode mixture layer of at least one of the positive electrode and the negative electrode, or a positive electrode, a negative electrode, a separator, and an electrolytic solution are provided, and the separator A model cell having a porous layer on at least one side of the sample cell was prepared, the model cell was held in a high-temperature bath, and the internal resistance value of the model cell was measured while increasing the temperature at a rate of 5 ° C./min. By measuring the temperature at which the internal resistance value is 5 times or more that before heating (resistance value measured at room temperature), this temperature can be evaluated as the shutdown temperature of the porous layer (of the present invention described later) The same shutdown method can be used for the nonaqueous battery separator).

  In addition, in the case of providing a shutdown function by including in the porous layer heat-melting resin fine particles having a melting point of 150 ° C. or less, from the viewpoint of ensuring a good shutdown function, the heat-melting resin in the porous layer The content of the fine particles is preferably 5% by volume or more, more preferably 20% by volume or more, and particularly preferably 50% by volume or more in the total volume of the constituent components of the porous layer.

The fine particles composed of an organic material or an inorganic material may be used alone or in combination of two or more. Further, as the fine particles having a heat resistant temperature of 150 ° C. or higher, oxide or hydroxide fine particles such as SiO ₂ , Al ₂ O ₃ , boehmite are particularly preferable.

The form of fine particles composed of an organic material or an inorganic material may be any form such as a spherical shape, an indeterminate shape, a plate shape, a polyhedral shape, a secondary particle shape, or a needle shape, but from the viewpoint of suppressing lithium dendrite Is preferably plate-shaped. Examples of the plate-like particles include various commercially available products. For example, “Sun Lovely” (SiO ₂ ) manufactured by Asahi Glass S Tech Co., Ltd., “NST-B1” pulverized product (TiO ₂ ) manufactured by Ishihara Sangyo Co., Ltd., Sakai Chemical Industry Co., Ltd. Plate-like barium sulfate “H series”, “HL series”, Hayashi Kasei “micron white” (talc), Hayashi Kasei “bengel” (bentonite), Kawai lime “BMM” and “BMT” (Boehmite), “Cerasure BMT-B” [Alumina (Al ₂ O ₃ )] manufactured by Kawai Lime Co., Ltd., “Seraph” (alumina) manufactured by Kinsei Matec Co., Ltd. ) Etc. are available. In addition, SiO ₂ , Al ₂ O ₃ , ZrO, and CeO ₂ can be produced by the method disclosed in Japanese Patent Laid-Open No. 2003-206475.

  When the fine particles composed of an organic material or an inorganic material are plate-like, in the porous layer, it is preferable to orient the fine particles so that the flat plate surface is substantially parallel to the surface of the porous layer, By using a separator having such a porous layer, the occurrence of a short circuit of the battery can be suppressed more favorably. This is because the fine particles are oriented as described above so that the fine particles are overlapped with each other on a part of the flat plate surface. Therefore, the void (through hole) from one side of the porous layer to the other side is not a straight line. This is considered to be formed in a bent shape (that is, the curvature is increased), and this prevents lithium dendrite from penetrating the porous layer, thereby suppressing the occurrence of a short circuit better. Presumed to be.

  As a form when the fine particles are plate-like particles, for example, the aspect ratio (ratio between the maximum length in the plate-like particles and the thickness of the plate-like particles) is 5 or more, more preferably 10 or more, and 100 Below, it is desirable that it is 50 or less. Further, the average value of the ratio of the major axis direction length to the minor axis direction length of the flat plate surface of the grains is preferably 0.3 or more, more preferably 0.5 or more (ie, the major axis length). And the length in the minor axis direction may be the same). When the plate-like fine particles have the aspect ratio as described above or the average value of the ratios of the major axis direction length and the minor axis direction length of the flat plate surface, the above-described short-circuit prevention effect is more effectively exhibited.

  In addition, the average value of the ratio of the length in the long axis direction to the length in the short axis direction of the flat plate surface when the fine particles are plate-like is, for example, image analysis of an image taken with a scanning electron microscope (SEM). It can ask for. Further, the aspect ratio in the case where the fine particles are plate-like can also be obtained by image analysis of an image taken by SEM.

  The average particle diameter of the fine particles composed of an organic material or an inorganic material is preferably 0.01 μm or more, more preferably 0.1 μm or more, preferably 3 μm or less, more preferably 1 μm or less.

  The average particle size of the fine particles composed of an organic material or an inorganic material as used in this specification is, for example, a laser scattering particle size distribution meter (for example, “LA-920” manufactured by HORIBA), Can be defined as the number average particle size measured by dispersing fine particles in a medium that does not swell (the average particle size shown in the examples below is a value determined by this method).

The specific surface area of the fine particles is preferably 100 m ² / g or less, preferably 50 m ² / g or less, and more preferably 30 m ² / g or less. If the specific surface area is too large, the amount of binder used to bind the fine particles to each other, the fine particles and the base material, and the electrode may become too large, resulting in poor battery output characteristics. There is a possibility that the moisture to be increased will increase the effect of suppressing the deterioration of the characteristics of the non-aqueous battery due to the use of the acrylic polymer. On the other hand, a suitable lower limit of the specific surface area of the fine particles is 1 m ² / g. Here, the specific surface area is a value measured by a BET method using nitrogen gas.

  In addition, when the porous layer of the present invention uses highly heat-resistant fine particles having a heat-resistant temperature of 150 ° C. or higher as described above, its action suppresses thermal shrinkage at high temperatures and enhances dimensional stability. Can do. In addition, when the porous layer of the present invention containing fine particles having a high heat resistance of 150 ° C. or higher is integrated with an electrode (positive electrode or negative electrode), the dimensions of the porous layer at a high temperature Stability can be further enhanced.

  Furthermore, even when a separator is composed of a porous layer containing fine particles with high heat resistance of 150 ° C. or higher and a porous resin sheet, the porous resin sheet is inferior in dimensional stability at high temperatures. Even so, the heat resistance of the porous resin sheet is suppressed by the action of fine particles having a heat-resistant temperature of 150 ° C. or higher, so that the heat shrinkage of the porous resin sheet is suppressed. The overall dimensional stability of the separator is improved. Therefore, in the present invention, by using a porous layer having high dimensional stability, for example, a separator composed only of a conventional polyethylene (PE) porous film (PE microporous film) is used. Since the occurrence of a short circuit due to the generated heat shrinkage can be prevented, the reliability and safety when the inside of the battery is abnormally overheated can be further improved.

  Thus, according to one embodiment of the present invention, it is possible to improve the reliability of preventing a short circuit due to the thermal contraction of the separator at a high temperature.

  The porous layer may contain a fibrous material having a heat resistant temperature of 150 ° C. or higher. For example, in the case where the separator is constituted only by the porous layer and the porous layer is not integrated with the electrode, the fibrous material is included from the viewpoint of reinforcing the porous layer and improving its handleability. It is preferable that the fibrous material is the main component of the separator. Also, when a separator is constituted by a porous layer and a porous resin film, or when the porous layer is integrated with an electrode, a fibrous material having a heat resistant temperature of 150 ° C. or more is contained for reinforcement. be able to.

  In particular, the porous layer contains a material that can be melted at a temperature of 140 ° C. or lower to block the pores of the porous layer (separator) and provide a function of blocking the movement of ions in the separator (so-called shutdown function). In such a case, the fibrous layer having a heat-resistant temperature of 150 ° C. or higher is also included in the porous layer, so that even if the temperature of the separator further increases by 20 ° C. or higher after shutdown due to heat generation in the battery, etc. The shape can be kept more stable.

  The fibrous material has a heat-resistant temperature of 150 ° C. or higher, is electrically insulating, is electrochemically stable, and is further described in detail below with a non-aqueous electrolyte (non-aqueous electrolyte), organic If it is stable to the solvent used for the coating liquid for porous layer formation containing the fine particle comprised with the material or the inorganic material, there will be no restriction | limiting in particular. The “fibrous material” in the present specification means that having an aspect ratio [length in the longitudinal direction / width (diameter) in a direction perpendicular to the longitudinal direction] of 4 or more. The aspect ratio of the fibrous material is preferably 10 or more.

  Specific constituent materials of the fibrous material include, for example, cellulose, modified cellulose (such as carboxymethyl cellulose), polypropylene (PP), polyester [polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT). And the like], resins such as polyacrylonitrile (PAN), aramid, polyamideimide, and polyimide; inorganic materials (inorganic oxides) such as glass, alumina, and silica; and the like. The fibrous material may contain one kind of these constituent materials, or may contain two or more kinds. In addition to the above-described constituent materials, the fibrous material may contain various known additives (for example, an antioxidant in the case of a resin) as necessary. Absent.

  Note that the fibrous material may be subjected to a surface treatment such as a corona discharge treatment or a treatment with a surfactant in order to enhance the adhesion with fine particles made of an organic material or an inorganic material.

  Although the diameter of a fibrous material should just be below the thickness of a porous layer, it is preferable that it is 0.01-5 micrometers, for example. If the diameter is too large, the entanglement between the fibrous materials may be insufficient, and the strength of the sheet-like material constituted by these, and consequently the strength of the porous layer may be reduced, making it difficult to handle. On the other hand, if the diameter is too small, the pores of the porous layer become too small, and the ion permeability tends to decrease, which may reduce the load characteristics of the battery.

  The fibrous material may be contained in the porous layer in a state where each fibrous material is independent, and the porous layer in a sheet-like material (woven fabric, non-woven fabric, etc.) composed of the fibrous material. It may be included.

  That is, the porous layer for a non-aqueous battery is formed so as to fill a void of a porous resin sheet such as a nonwoven fabric, and the porous resin sheet is integrated in the porous layer. Also good.

  For example, the state of the fibrous material in the porous layer (sheet-like material) is preferably such that the angle of the long axis (axis in the long direction) to the separator surface is 30 ° or less on average, 20 ° The following is more preferable.

  The content of fine particles composed of organic material or inorganic material in the porous layer is the composition of the porous layer from the viewpoint of more effectively exerting the effect of using fine particles composed of organic material or inorganic material. What is necessary is just to set it as 50 mass% or more in the total mass of a component, It is preferable that it is 70 mass% or more, It is more preferable that it is 80 mass or more, It is still more preferable that it is 90 mass% or more.

  In addition, when the porous layer contains the fibrous material, the content of the fibrous material in the porous layer is the configuration of the porous layer from the viewpoint of more effectively exerting the effect of using the fibrous material. The total volume of the components is preferably 10% by volume or more, and more preferably 30% by volume or more. On the other hand, in the porous layer containing the fibrous material, if the content of the fibrous material is too much, the content of other components (such as fine particles composed of an organic material or an inorganic material) decreases, Since the effects of these other components may be reduced, the content of the fibrous material is preferably 90% by volume or less, and 70% by volume or less in the total volume of the constituent components of the porous layer. Is more preferable.

  The thickness of the porous layer is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 2 μm or more, and preferably 10 μm or less, preferably 5 μm or less. Is more preferable.

The porosity of the porous layer is preferably 20 to 60%. The porosity of the porous layer can be calculated by calculating the sum of each component i from the thickness of the porous layer, the mass per area, and the density of the constituent components using the following formula (3).
P = 100− (Σa _i / ρ _i ) × (m / t) (3)

Here, in the formula (3), a _i : ratio of the component i expressed by mass%, ρ _i : density of the component i (g / cm ³ ), m: mass per unit area of the porous layer (g / Cm ² ), t: thickness of the porous layer (cm).

  The porous layer of the present invention comprises an acrylic polymer containing fine particles composed of an organic material or an inorganic material, a binder component, and a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate Further, a coating liquid for forming a porous layer (composition containing a solvent) containing a fibrous material or the like used as necessary is applied to the surface of a substrate, for example, a porous resin sheet (non-inventive of the present invention). A method for producing a separator for a water battery) and a method of applying the present invention to a surface of an electrode mixture layer of an electrode for a non-aqueous battery (when making an electrode for a non-aqueous battery of the present invention) and drying. Can be obtained by:

  In the case of producing a separator in which a porous layer is integrated with a porous resin sheet (woven fabric, nonwoven fabric, etc.) made of a fibrous material, for example, the coating liquid is not used for coating, but an immersion liquid. And impregnating the sheet-like material therein, and if necessary, promote the penetration of the immersion liquid into the gap of the sheet-like material through the gap, or apply the coating liquid to the sheet-like material. Then, the porous layer can be formed through a drying step after the coating liquid is allowed to enter the gap of the sheet-like material through a gap.

  The coating liquid for forming a porous layer (including the case where it is used as an immersion liquid; the same applies hereinafter) includes fine particles composed of an organic material or an inorganic material, a binder component, and a structural unit based on (meth) acrylic acid. It contains an acrylic acid-based polymer containing a structural unit based on (meth) acrylate, and further contains a fibrous material used as necessary, and these contain a solvent containing water (including a dispersion medium. The same applies hereinafter). ) Is dissolved or dispersed. In general, the acrylic polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate, which is a thickener, is dissolved in the solvent, and the binder component is also included. It can also be dissolved in a solvent. The solvent used in the coating liquid may be water alone, but the fine particles are uniformly dispersed, the acrylic acid polymer is dissolved well, or the binder component is dissolved uniformly. For the purpose of dispersing or controlling the interfacial tension, a solvent other than water such as alcohols (methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, etc.) can be added as appropriate.

  The viscosity of the coating liquid (viscosity obtained by the method described in Examples below) is preferably 10 to 1000 mPa · s, and preferably 20 to 700 mPa · s from the viewpoint of improving the coating property. Is more preferable.

  The separator for nonaqueous batteries of the present invention (hereinafter simply referred to as “separator”) is obtained by integrating the porous layer of the present invention with a porous resin sheet.

  In the separator of the present invention, when the shutdown function is ensured by a porous resin sheet, for example, a porous resin film such as a microporous membrane made of polyolefin, the resin constituting the porous resin film includes the heat-meltable fine particles. The same resin (thermoplastic resin) as the resin to be used can be used. The shutdown temperature of the porous resin film is preferably set in the range of 100 ° C. to 150 ° C., more preferably 140 ° C. or less. Therefore, the thermoplastic resin constituting this also has a melting point of 100 to 150. It is desirable to use one having a temperature of 140 ° C., more preferably 140 ° C. or less.

  On the other hand, when the heat resistance of the separator is emphasized and the shutdown function is not given, a heat resistant porous resin sheet can be used. As a specific constituent material of such a porous resin sheet, the heat-resistant temperature is 150 ° C. or more, it is stable with respect to the non-aqueous electrolyte used in the battery, and further stable with respect to the oxidation-reduction reaction inside the battery. Any resin can be used. More specifically, heat-resistant resins such as polyimide, polyamideimide, aramid, polytetrafluoroethylene, polysulfone, polyurethane, PAN, polyester (PET, PBT, PEN, etc.) can be mentioned.

In the porous resin sheet, for example, a porous film composed of the above-described exemplary resin used in a conventionally known non-aqueous battery, that is, an ion produced by a solvent extraction method, a dry type or a wet drawing method, etc. A permeable porous film (microporous film), fibrous sheets, such as a woven fabric and a nonwoven fabric, can be used. In addition, a film microporous by a foaming method using a drug, supercritical CO ₂ or the like can also be used.

  In the separator of the present invention, because of the action of the porous layer of the present invention, it is possible to ensure good heat resistance (heat shrinkage resistance) even when a porous resin sheet that is easily heat-shrinkable is applied. It is preferable to employ a porous resin sheet that can ensure a good shutdown function, and it is more preferable to use a porous film (microporous film) made of polyolefin (PE, PP, ethylene-propylene copolymer, etc.).

  In the separator of the present invention, each of the porous layer and the porous resin sheet does not need to be one layer, and one or both may be two or more layers, but the number of layers of the separator is excessively increased. For example, the total number of layers of the porous layer and the porous resin sheet is preferably 5 or less.

  From the viewpoint of enhancing the short-circuit prevention effect of the non-aqueous battery to which the separator is applied, ensuring the strength of the separator, and improving its handleability, the thickness of the separator of the present invention is preferably 3 μm or more, for example. More preferably, it is 5 μm or more. On the other hand, from the viewpoint of further increasing the energy density of the nonaqueous battery to which the separator is applied, the thickness of the separator is preferably 50 μm or less, and more preferably 30 μm or less.

  In addition, in the case of a porous resin film, the thickness of the porous resin sheet (the total thickness when the separator has a plurality of porous resin sheets) is expressed by a specific value, which is 5 μm or more. In addition, it is preferably 30 μm or less. Regarding the thickness of the porous layer in the separator, when the separator has a plurality of porous layers, it is preferable that the total thickness satisfies the preferred thickness of the porous layer described above.

  Further, the separator of the present invention preferably has a thermal shrinkage rate at 150 ° C. measured in a non-aqueous electrolyte (its solvent) of 5% or less. By configuring the porous layer as the heat-resistant layer of the separator, such a heat shrinkage rate can be ensured.

In addition, the porosity of the separator is preferably 20% or more, and preferably 30% or more in a dried state, in order to ensure the amount of the nonaqueous electrolyte retained and to improve the ion permeability. It is more preferable. On the other hand, from the viewpoint of ensuring the strength of the separator and preventing internal short circuit, the porosity of the separator is preferably 70% or less, more preferably 60% or less, in a dry state. Note that the porosity of the separator: P (%) is obtained by setting m as the mass per unit area of the separator (g / cm ² ) and t as the thickness of the separator (cm) in the above formula (3). , Can be obtained using the above equation (3).

Furthermore, in the above formula (3), m is the mass per unit area (g / cm ² ) of the porous resin sheet, and t is the thickness (cm) of the porous resin film. Can also be used to determine the porosity: P (%) of the porous resin sheet. It is preferable that the porosity of the porous resin sheet calculated | required by this method is 30 to 70%.

  Further, the strength of the separator is desirably 50 g or more in terms of piercing strength using a needle having a diameter of 1 mm. If the piercing strength is too low, a short circuit may occur due to the piercing of the separator when lithium dendrite crystals are generated.

The air permeability of the separator is measured by a method according to JIS P 8117, and is 10 to 300 sec as a Gurley value indicated by the number of seconds that 100 ml of air passes through the membrane under a pressure of 0.879 g / mm ^2. It is desirable to be. If the air permeability is too high, the ion permeability is reduced, and if it is too low, the strength of the separator may be reduced.

Furthermore, it is desirable that the Gurley value of the separator satisfies the relationship of the following formula (4).
Gs ≦ max {Ga, Gb} +10 (4)

In the above formula (4), Gs: Gurley value of the separator, Ga: Gurley value of the porous resin film, Gurley value of the porous layer of the present invention, max {a, b}: whichever is larger of a and b is there. However, Gb is calculated | required using following formula (5).
Gb = Gs-Ga (5)

  The piercing strength and air permeability can be ensured by using the separator having the configuration described so far.

  The nonaqueous battery electrode of the present invention (hereinafter simply referred to as “electrode”) is obtained by forming the porous layer of the present invention on an electrode mixture layer (positive electrode mixture layer or negative electrode mixture layer). The electrode of the present invention is used for a positive electrode or a negative electrode of a nonaqueous battery. In addition, as a battery in which the electrode of the present invention is used, there are a non-aqueous primary battery and a non-aqueous secondary battery. Hereinafter, the main non-aqueous secondary battery is used as a battery in which the electrode of the present invention is used. Details of the electrode having a configuration suitable for the above will be described.

  As an electrode of the present invention when used for a positive electrode of a nonaqueous battery, for example, an electrode mixture layer (positive electrode mixture layer) containing a positive electrode active material, a conductive additive, a binder, and the like is used. Alternatively, a structure having a structure in which the porous layer of the present invention is formed on both electrode mixture layers on both surfaces is exemplified.

Examples of the positive electrode active material include lithium cobalt oxides such as LiCoO ₂ ; lithium manganese oxides such as LiMnO ₂ and Li ₂ MnO ₃ ; lithium nickel oxides such as LiNiO ₂ ; LiMn ₂ O ₄ and Li _4/3 Ti _5/3 O ₄ and other spinel-structured lithium-containing composite oxides; LiFePO ₄ and other olivine-structured lithium-containing composite oxides; oxides obtained by substituting the above-mentioned oxides with various elements; Only one of these may be used, or two or more may be used in combination.

  Examples of the conductive auxiliary agent related to the positive electrode mixture layer include graphites such as natural graphite (flaky graphite, etc.) and artificial graphite; acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc. It is preferable to use carbon materials such as carbon blacks; carbon fibers; and conductive fibers such as metal fibers; carbon fluorides; metal powders such as aluminum; zinc oxide; Conductive whiskers; conductive metal oxides such as titanium oxide; organic conductive materials such as polyphenylene derivatives; and the like can also be used.

  Examples of the binder related to the positive electrode mixture layer include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), and polyvinylpyrrolidone (PVP).

  For example, the positive electrode mixture containing a positive electrode active material, a conductive additive, a binder, and the like is dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP) or water to form a paste-like or slurry-like positive electrode mixture. An agent-containing composition is prepared (however, the binder may be dissolved in a solvent), applied to one or both sides of the current collector, dried, and then subjected to a calender treatment as necessary. Using the positive electrode as a base material, it can be produced through the step of forming the porous layer of the present invention on the positive electrode mixture layer by the method described above. However, the positive electrode is not limited to those manufactured by the above method, and may be manufactured by other methods.

  As the positive electrode current collector, an aluminum foil, a punching metal, a net, an expanded metal, or the like can be used, but an aluminum foil is usually used. The thickness of the positive electrode current collector is preferably 10 to 30 μm.

  Moreover, you may form the lead body for electrically connecting with the other member in a non-aqueous battery according to a conventional method as needed.

  As composition of a positive mix layer, it is preferable that content of a positive electrode active material is 80.0-99.8 mass%, for example, and content of a conductive support agent is 0.1-10 mass%. It is preferable that the binder content is 0.1 to 10% by mass. Moreover, it is preferable that the thickness of a positive mix layer is 1-100 micrometers per single side | surface of a collector.

  As an electrode of the present invention when used for a negative electrode of a nonaqueous battery, for example, an electrode mixture layer (a negative electrode mixture layer) containing a negative electrode active material and a binder, and further, if necessary, a conductive additive, etc. And a structure in which the porous layer of the present invention is formed on one or both surfaces of the current collector and on the electrode mixture layer.

  The negative electrode active material may be any material that can be doped / undoped with lithium ions. For example, graphite, pyrolytic carbons, cokes, glassy carbon, fired organic polymer compound, mesocarbon microbeads, carbon Examples thereof include carbonaceous materials such as fibers and activated carbon. Moreover, lithium or a lithium-containing compound can also be used as the negative electrode active material. Examples of the lithium-containing compound include tin oxide, silicon oxide, nickel-silicon alloy, magnesium-silicon alloy, tungsten oxide, lithium iron composite oxide, lithium-aluminum, and lithium-lead. , Lithium-indium, lithium-gallium, lithium-indium-gallium, and other lithium alloys. Some of these exemplary negative electrode active materials do not contain lithium at the time of manufacture, but are in a state containing lithium at the time of charging.

  As the binder relating to the negative electrode mixture layer, the same binders as those exemplified above as the binder relating to the positive electrode mixture layer can be used.

  When the conductive additive is contained in the negative electrode mixture layer, the same conductive assistants as those exemplified above as the conductive auxiliary agent related to the positive electrode mixture layer can be used.

  The negative electrode includes, for example, a negative electrode active material, a binder, and a negative electrode mixture containing a conductive auxiliary agent, if necessary, in a solvent such as NMP or water, and a paste-like or slurry-like negative electrode mixture-containing composition (However, the binder may be dissolved in a solvent.) This is applied to one or both sides of the current collector, dried, and then calendered as necessary. As a material, it can manufacture through the process of forming the porous layer of this invention on the negative mix layer by the said method. However, the negative electrode is not limited to those manufactured by the above method, and may be manufactured by other methods.

  The negative electrode current collector may be, for example, a foil, punched metal, expanded metal, net, or the like made of copper, stainless steel, nickel, titanium, or an alloy thereof. Usually, copper having a thickness of 5 to 30 μm is used. A foil is preferably used.

  Moreover, you may form the lead body for electrically connecting with the other member in a nonaqueous battery according to a conventional method as needed.

  In the negative electrode mixture layer, for example, the content of the negative electrode active material is preferably 70 to 99% by mass, and the content of the binder is preferably 1 to 30% by mass. Moreover, when using a conductive support agent, it is preferable that content of the conductive support agent in a negative mix layer is 1-20 mass%. Furthermore, the thickness of the negative electrode mixture layer is preferably 1 to 100 μm per one side of the current collector.

  The nonaqueous battery of the present invention has a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, and the separator is the separator of the present invention, or has a positive electrode, a negative electrode, and a nonaqueous electrolyte, and the positive electrode and the negative electrode It is sufficient that at least one of the electrodes is the electrode of the present invention, and there is no particular limitation on the other configuration and structure. Conventionally known non-aqueous batteries (non-aqueous secondary batteries such as lithium secondary batteries and the like) Various configurations and structures employed in non-aqueous primary batteries) can be applied.

  In the nonaqueous battery of the present invention, when the separator of the present invention is not used, the porous layer (the porous layer of the present invention) according to the electrode of the present invention plays the role of a separator, but a separate separator is used. The porous resin film for constituting the separator can be used as the separator in that case. In addition, in the nonaqueous battery of the present invention, when the electrode of the present invention is not used as a positive electrode, the positive electrode has the same configuration as the electrode of the present invention except that it has the porous layer of the present invention. Can be used. Furthermore, in the non-aqueous battery of the present invention, when the electrode of the present invention is not used as a negative electrode, the negative electrode having the same configuration as that of the electrode of the present invention is used except that the positive electrode has the porous layer of the present invention. Can be used.

  In the nonaqueous battery of the present invention, the positive electrode and the negative electrode are laminated with a separator interposed therebetween, or are laminated so that a porous layer formed on at least one electrode mixture layer is interposed therebetween. It is used in the form of a laminated body (laminated electrode body) or a wound body (wound electrode body) obtained by winding this laminated body in a spiral shape.

As the non-aqueous electrolyte of the non-aqueous battery, as described above, a solution (non-aqueous electrolyte) in which a lithium salt is dissolved in an organic solvent is used. The lithium salt is not particularly limited as long as it dissociates in a solvent to form Li ⁺ ions and does not cause a side reaction such as decomposition in a voltage range used as a battery. For example, inorganic lithium salts such as LiClO ₄ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ ; LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , Li ₂ C ₂ F ₄ (SO ₃ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiC _n F _{2n + 1} SO ₃ (n ≧ 2), LiN (R _f OSO ₂ ) ₂ [where R _f is a fluoroalkyl group], etc .; Can be used.

  The organic solvent used for the non-aqueous electrolyte is not particularly limited as long as it dissolves the lithium salt and does not cause a side reaction such as decomposition in a voltage range used as a battery. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; chain esters such as methyl propionate; cyclic esters such as γ-butyrolactone; Chain ethers such as ethane, diethyl ether, 1,3-dioxolane, diglyme, triglyme and tetraglyme; cyclic ethers such as dioxane, tetrahydrofuran and 2-methyltetrahydrofuran; nitriles such as acetonitrile, propionitrile and methoxypropionitrile; Sulfites such as ethylene glycol sulfite; and the like, and these may be used alone. , It may be used in combination of two or more thereof. In order to obtain a battery with better characteristics, it is desirable to use a combination that can obtain high conductivity, such as a mixed solvent of ethylene carbonate and chain carbonate. In addition, vinylene carbonates, 1,3-propane sultone, diphenyl disulfide, cyclohexylbenzene, biphenyl, and fluorobenzene are used for the purpose of improving safety, charge / discharge cycleability, and high-temperature storage properties of these non-aqueous electrolytes. An additive such as t-butylbenzene may be added as appropriate.

  The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.5 to 1.5 mol / l, and more preferably 0.9 to 1.25 mol / l.

  Also, instead of the organic solvent, melting at room temperature such as ethyl-methylimidazolium trifluoromethylsulfonium imide, heptyl-trimethylammonium trifluoromethylsulfonium imide, pyridinium trifluoromethylsulfonium imide, guanidinium trifluoromethylsulfonium imide A salt can also be used.

  Further, a polymer material that contains the non-aqueous electrolyte and gels may be added to make the non-aqueous electrolyte into a gel (gel electrolyte) for use in a battery. Polymer materials for making the non-aqueous electrolyte into a gel include PVDF, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), PAN, polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymer And a known host polymer capable of forming a gel electrolyte, such as a crosslinked polymer having an ethylene oxide chain in the main chain or side chain, and a crosslinked poly (meth) acrylate.

  Examples of the form of the nonaqueous battery of the present invention include a tubular shape (such as a rectangular tube shape or a cylindrical shape) using a steel can, an aluminum can, or the like as an outer can. Moreover, it can also be set as the soft package battery which used the laminated film which vapor-deposited the metal as an exterior body.

  The nonaqueous battery of the present invention can be applied to the same applications as conventionally known nonaqueous secondary batteries such as lithium secondary batteries and nonaqueous primary batteries.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.

Example 1
<Preparation of positive electrode>
LiCoO _{2 as a} positive electrode active material: 90 parts by mass, carbon black as a conductive auxiliary agent: 5 parts by mass are added and mixed, and a solution in which 5 parts by mass of PVDF as a binder is dissolved in NMP is added to this mixture. The mixture was mixed to obtain a positive electrode mixture-containing slurry, which was passed through a 70-mesh net to remove a large particle size. This positive electrode mixture-containing slurry is uniformly applied to both sides of a positive electrode current collector made of an aluminum foil having a thickness of 15 μm, dried, and then compression-molded by a roll press machine to a total thickness of 105 μm, followed by cutting. Then, an aluminum lead body was welded to the exposed portion of the current collector to produce a strip-like positive electrode.

<Production of negative electrode>
Artificial graphite as a negative electrode active material: 95 parts by mass and PVDF as a binder: 5 parts by mass were mixed, and NMP was further added and mixed to prepare a negative electrode mixture-containing paste. This negative electrode mixture-containing paste is uniformly coated on both sides of a negative electrode current collector made of copper foil having a thickness of 10 μm, dried, and then compression-molded by a roll press machine to a total thickness of 100 μm, followed by cutting. Then, a nickel lead body was welded to the exposed portion of the current collector to produce a strip-shaped negative electrode.

<Preparation of non-aqueous electrolyte>
In a solvent mixture of ethylene carbonate, methyl ethyl carbonate and diethyl carbonate having a volume ratio of 10:10:30, LiPF ₆ was dissolved at a concentration of 1.0 mol / l, and vinylene carbonate was added to the total amount of the non-aqueous electrolyte. The non-aqueous electrolyte was prepared by adding 2.5% by mass.

<Preparation of separator>
Boehmite powder (plate shape, average particle size: 1 μm, aspect ratio: 10, specific surface area: 8 m ² / g): 4000 g, fine particles having a heat-resistant temperature of 150 ° C. or higher, are added to water: 4000 g in four portions, A uniform slurry was prepared by stirring at 2800 rpm for 5 hours with a disper. To this slurry, 400 g of binder SBR (solid content 50%) and sodium partially neutralized polyacrylic acid as a thickener [“Viscomate NP-800” (trade name) manufactured by Showa Denko, neutralization degree: 35%] of 1.5% strength aqueous solution: 267 g, and further added water, stirred at room temperature until uniformly dispersed, and a slurry for forming a porous layer having a solid content concentration of 35% by weight (coating solution) ) Was prepared.

  The slurry for forming a porous layer is applied by a microgravure coater on a treated surface of a PE microporous membrane (thickness: 16 μm, porosity: 40%, PE melting point: 135 ° C.) subjected to corona discharge treatment on one side. And drying to form a porous layer, thereby obtaining a separator having a thickness of 20 μm.

<Battery assembly>
The separator obtained as described above was laminated while being interposed between the positive electrode and the negative electrode so that the porous layer was directed to the positive electrode side, and wound into a spiral shape to produce a wound electrode body. The obtained wound electrode body is put into an iron outer can (battery case) having a diameter of 18 mm and a height of 65 mm, and after sealing with a nonaqueous electrolyte, sealing is performed, and the nonaqueous water having the structure shown in FIG. A secondary battery was produced.

  Here, the battery shown in FIG. 1 will be described. In the nonaqueous secondary battery shown in FIG. 1, the positive electrode 1 and the negative electrode 2 are spirally wound via the separator 3, and nonaqueous electrolysis is used as a wound electrode body. It is accommodated in the battery case 5 together with the liquid 4. In FIG. 1, in order to avoid complication, the current collectors used for manufacturing the positive electrode 1 and the negative electrode 2 are not shown, and each layer of the separator is not shown.

  The battery case 5 is made of stainless steel, and an insulator 6 made of PP is disposed at the bottom of the battery case 5 prior to the insertion of the wound electrode body. The sealing plate 7 is made of aluminum and has a disk shape. A thin portion 7a is provided at the center of the sealing plate 7, and a pressure introduction port 7b for allowing the battery internal pressure to act on the explosion-proof valve 9 around the thin portion 7a. As a hole. And the protrusion part 9a of the explosion-proof valve 9 is welded to the upper surface of this thin part 7a, and the welding part 11 is comprised. The thin-walled portion 7a provided on the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are shown only on the cut surface for easy understanding on the drawing, and the contour behind the cut surface is The illustration is omitted. In addition, the welded portion 11 of the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 is also illustrated in an exaggerated state so as to facilitate understanding on the drawing.

  The terminal plate 8 is made of rolled steel, has a nickel plating on the surface, and has a hat shape with a peripheral edge portion having a hook shape. The terminal plate 8 is provided with a gas discharge port 8a. The explosion-proof valve 9 is made of aluminum and has a disk shape, and a central portion is provided with a protruding portion 9a having a tip portion on the power generation element side (lower side in FIG. 1) and a thin portion 9b. As described above, the lower surface of the protruding portion 9a is welded to the upper surface of the thin portion 7a of the sealing plate 7 to constitute the welded portion 11. The insulating packing 10 is made of PP and has an annular shape. The insulating packing 10 is arranged at the upper part of the peripheral portion of the sealing plate 7. The explosion-proof valve 9 is arranged at the upper part of the insulating packing 10. The gap between the two is sealed so that the non-aqueous electrolyte does not leak between the two. The annular gasket 12 is made of PP, the lead body 13 is made of aluminum, the sealing plate 7 and the positive electrode 1 are connected, an insulator 14 is disposed on the upper part of the wound electrode body, and the negative electrode 2 and the battery case 5 The bottom is connected by a lead body 15 made of nickel.

  In this non-aqueous secondary battery, the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are in contact with each other at the welded portion 11, and the peripheral portion of the explosion-proof valve 9 and the peripheral portion of the terminal plate 8 are in contact. Since the positive electrode 1 and the sealing plate 7 are connected by the lead body 13 on the positive electrode side, in the normal state, the positive electrode 1 and the terminal plate 8 are connected to the lead body 13, the sealing plate 7, the explosion-proof valve 9 and their welding. The portion 11 provides an electrical connection and functions normally as an electrical circuit.

  When the battery is exposed to a high temperature and an abnormal situation occurs, gas is generated inside the battery and the internal pressure of the battery rises, the internal pressure rises and the central portion of the explosion-proof valve 9 is moved in the internal pressure direction. (The upper direction in FIG. 1) is deformed, and accordingly, the thin portion 7a integrated with the welded portion 11 is subjected to a shearing force to break the thin portion 7a, or the protruding portion of the explosion-proof valve 9 After the welded part 11 between 9a and the thin part 7a of the sealing plate 7 is peeled off, the thin part 9b provided in the explosion-proof valve 9 is cleaved and the gas is discharged from the gas outlet 8a of the terminal plate 8 to the outside of the battery. It is designed to prevent the battery from bursting.

  The non-aqueous secondary battery of this example has a design electric capacity of 1400 mAh when charged to 4.2 V (the positive electrode potential is 4.3 V with respect to Li) (for all examples and comparative examples described later). The same applies to the battery).

Example 2
In the preparation of the slurry for forming the porous layer, a separator having a thickness of 20 μm was prepared in the same manner as in Example 1 except that 800 g of a 1.5% strength aqueous solution of sodium partially neutralized polyacrylic acid was added. And the non-aqueous secondary battery was produced like Example 1 except having used the said separator.

Example 3
In the preparation of the slurry for forming the porous layer, the thickener was changed to a partially neutralized polyacrylic acid sodium (“Viscomate NP-700” (trade name) manufactured by Showa Denko) with a neutralization degree of 50%. Produced a separator having a thickness of 20 μm in the same manner as in Example 2. And the non-aqueous secondary battery was produced like Example 2 except having used the said separator.

Example 4
Instead of the PE microporous membrane, a microporous membrane in which three layers of PP layer and PE layer are laminated in the order of PP / PE / PP (thickness: 16 μm, porosity: 45%, thickness of each layer; PP layer: A separator having a thickness of 20 μm was produced in the same manner as in Example 1 except that 5 μm / PE layer: 6 μm / PP layer: 5 μm) was used. And the non-aqueous secondary battery was produced like Example 1 except having used the said separator.

Comparative Example 1
In the preparation of the slurry for forming the porous layer, 2000 g of a 2% aqueous solution of CMC (“2200” manufactured by Daicel) was added in place of the 1.5% aqueous solution of polyacrylic acid sodium partially neutralized product. Except for the above, a separator having a thickness of 20 μm was produced in the same manner as in Example 1. And the non-aqueous secondary battery was produced like Example 1 except having used the said separator.

Comparative Example 2
In the preparation of the slurry for forming the porous layer, a separator having a thickness of 20 μm was prepared in the same manner as in Example 1 except that 1333 g of a 1.5% strength aqueous solution of sodium partially neutralized polyacrylic acid was added. And the non-aqueous secondary battery was produced like Example 1 except having used the said separator.

Comparative Example 3
In the preparation of the slurry for forming the porous layer, a slurry for forming the porous layer was prepared in the same manner as in Example 1 except that 80 g of a 1.5% aqueous solution of sodium partially neutralized polyacrylic acid was added. When applied on a PE microporous film, the slurry had a low viscosity, and a homogeneous separator could not be produced. For this reason, the separator and the non-aqueous secondary battery using the separator were not evaluated.

Comparative Example 4
In the preparation of the slurry for forming the porous layer, the same procedure as in Example 1 was performed except that the thickener was changed to a completely neutralized polyacrylic acid sodium (“Viscomate F480SS” (trade name) manufactured by Showa Denko). A separator having a thickness of 20 μm was produced, and a nonaqueous secondary battery was produced in the same manner as in Example 1 except that the separator was used.

Comparative Example 5
In the preparation of the slurry for forming the porous layer, the slurry for forming the porous layer was prepared in the same manner as in Example 1 except that the thickener was changed to a homopolymer of polyacrylic acid (an unneutralized polymer). When prepared and applied onto a PE microporous membrane, the slurry had a low viscosity, and a homogeneous separator could not be produced. For this reason, the separator and the non-aqueous secondary battery using the separator were not evaluated.

  About the slurry for porous layer formation prepared in Examples 1-4 and Comparative Examples 1-5, the viscosity was measured on condition of the following.

(Measurement of viscosity of slurry for forming porous layer)
The viscosity of each slurry for forming a porous layer was measured using a cone of 1 ° 34 ′ in an environment of 25 ° C. using an E-type viscometer (VISCONIC ED type) manufactured by Tokyo Keiki Co., Ltd. P. M.M. Measurement was performed at (shear rate 3.83 s ⁻¹ ).

  Moreover, about the separator produced in Examples 1-4 and Comparative Examples 1, 2, and 4, the moisture content was measured on condition of the following.

(Measurement of moisture content in separator)
Each separator was allowed to stand in a glove box having a dew point of −50 ° C. for 12 hours or more, and then a measurement sample was placed in a 150 ° C. heating furnace in which nitrogen gas was flowed and held for 1 minute. The nitrogen gas which flowed through each separator after that was introduce | transduced into the measurement cell of the Karl Fischer moisture meter, and the moisture content was measured. The moisture content is measured in a glove box with a dew point of -50 ° C. The integrated value up to the end of titration is taken as the moisture content (mass standard), and the moisture content of each separator is calculated by dividing the measured value by the mass of the separator sample. did.

  Furthermore, the charge / discharge characteristics of the nonaqueous secondary batteries produced in Examples 1 to 4 and Comparative Examples 1, 2, and 4 were evaluated under the following conditions.

(Evaluation of charge / discharge characteristics of non-aqueous secondary battery)
For each non-aqueous secondary battery, constant current charging is performed until the battery voltage reaches 4.2 V at a current value of 0.2 C, and then constant current-constant voltage charging is performed to perform constant voltage charging at 4.2 V. It was. The total charging time until the end of charging was 15 hours. And the charge capacity of each battery at that time was measured. Next, each battery after charging was discharged at a discharge current of 0.2 C until the battery voltage reached 3.0 V, and the discharge capacity was measured. And about each battery, the ratio of the discharge capacity with respect to charge capacity was represented by the percentage, and charge / discharge efficiency was calculated | required.

  Table 1 shows the constitution of the thickener used in the slurry for forming a porous layer prepared in Examples 1 to 4 and Comparative Examples 1 to 5. Table 2 shows the measurement and evaluation results.

  As shown in Table 1 and Table 2, a slurry for forming a porous layer using the acrylic acid polymer as a thickener was used, and a separator having an appropriate content in the porous layer of the acrylic acid polymer was used. In the non-aqueous secondary batteries of Examples 1 to 4, since the water content of the separator was kept low, the charge / discharge efficiency was very close to 100%, and it was confirmed that the batteries operated well.

  On the other hand, the batteries of Comparative Examples 1, 2 and 4 used a separator having a higher water content due to the thickener contained in the porous layer, so the charge / discharge efficiency was lowered, and the water content was The generation of gas due to the effect of was also noticeable.

1 Positive electrode 2 Negative electrode 3 Separator 4 Nonaqueous electrolyte

Claims (12)

A porous layer containing fine particles composed of an organic material or an inorganic material and a water-soluble resin,
The content of the fine particles is 50% by mass or more,
As the water-soluble resin, an acrylic acid polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate is contained,
The content of the acrylic acid polymer is 0.05 to 0.45% by mass,
Furthermore, the porous layer for nonaqueous batteries characterized by containing a binder component.   The porous layer for a non-aqueous battery according to claim 1, wherein the (meth) acrylate is an alkali metal salt. When the number of moles of the structural unit based on the (meth) acrylic acid and the structural unit based on the (meth) acrylic acid salt is a and b, the acrylic acid polymer has a neutralization degree calculated from the following formula: The porous layer for a nonaqueous battery according to claim 1 or 2, wherein the porous layer is 30% or more and 70% or less.
Degree of neutralization (%) = b ÷ (a + b) × 100   The porous layer for a nonaqueous battery according to claim 1, wherein the acrylic acid polymer is a partially neutralized product of polyacrylic acid.   The porous layer for a non-aqueous battery according to claim 1, wherein the fine particles are oxide or hydroxide fine particles.   Content of the said binder is 0.5-10 mass%, The porous layer for non-aqueous batteries in any one of Claims 1-5. It is a manufacturing method of the porous layer for nonaqueous batteries in any one of Claims 1-6,
It contains an acrylic acid polymer including fine particles composed of an organic material or an inorganic material, a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate, a binder component, and a solvent. The manufacturing method of the porous layer for non-aqueous batteries characterized by having the process of apply | coating a coating liquid to the base-material surface, and drying.   A nonaqueous battery separator, wherein the porous layer for a nonaqueous battery according to any one of claims 1 to 6 is integrated with a porous resin sheet.   The separator for a nonaqueous battery according to claim 8, wherein the porous resin sheet is a polyolefin microporous membrane.   A nonaqueous battery electrode comprising an electrode mixture layer containing an active material and the porous layer for a nonaqueous battery according to any one of claims 1 to 6 on the electrode mixture layer. .   A nonaqueous battery comprising a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, wherein the separator is the separator for a nonaqueous battery according to claim 8 or 9.   A nonaqueous battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte, wherein at least one of the positive electrode and the negative electrode is the electrode for a nonaqueous battery according to claim 10.

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