JP7037946B2 - Porous layer for non-water batteries, its manufacturing method, separator for non-water batteries, electrodes for non-water batteries and non-water batteries - Google Patents

Description

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

Lithium secondary batteries, which are a type of non-water batteries, are widely used as power sources for mobile devices such as mobile phones and notebook personal computers because of their high energy density. As the performance of mobile devices increases, the capacity of lithium secondary batteries tends to increase further, and it is important to ensure safety.

In the current lithium secondary battery, for example, a polyolefin-based porous film having a thickness of about 10 to 30 μm is used as a separator interposed between the positive electrode and the negative electrode. In addition, as the material of the separator, the constituent resin of the separator is melted at a temperature 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 shut-off effect, polyethylene having a low melting point may be applied.

By the way, as such a separator, for example, a uniaxially stretched or biaxially stretched film is used in order to make it porous and improve its strength. Since such a separator is supplied as a film that exists alone, a certain strength is required in terms of workability and the like, and this is secured by the stretching. However, in such a stretched film, the crystallinity is increased and the shutdown temperature is also increased to a temperature close to the thermal runaway temperature of the battery, so it is said that the margin for ensuring the safety of the battery is sufficient. hard.

Further, the film is distorted by the stretching, and when it is exposed to a high temperature, there is a problem that shrinkage occurs due to residual stress. The shrinkage temperature is very close to the shutdown temperature. Therefore, when using a polyolefin-based porous film separator, when the battery temperature reaches the shutdown temperature due to abnormal charging or the like, the current must be immediately reduced to prevent the battery temperature from rising. This is because if the vacancies are not sufficiently closed and the current cannot be reduced immediately, the temperature of the battery easily rises to the contraction temperature of the separator, and there is a risk of ignition due to an internal short circuit.

As a technique for preventing a short circuit due to heat shrinkage of such a separator and improving 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 resin porous film containing a thermoplastic resin. It has been proposed to use the separator of (Patent Documents 1, 2, etc.).

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

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

Japanese Unexamined Patent Publication No. 2008-12396 Japanese Unexamined Patent Publication No. 2008-21791 International Publication No. 2015/046126

By the way, in the porous layer, a step of applying a coating liquid such as a slurry or a paste prepared by dispersing fine particles made of an organic material or an inorganic material in a solvent is applied to the surface of a resin porous membrane or an electrode. Although it is generally formed through the process, carboxymethyl cellulose (CMC) or the like is used as a thickener in this coating liquid for the purpose of facilitating the adjustment of the thickness of the coating film after coating. Is normal.

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

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

The porous layer for a non-aqueous battery of the present invention is a porous layer containing fine particles made 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. The water-soluble resin contains an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylic acid salt, and the content of the acrylic acid-based polymer is 0.05 to It is 0.45% by mass and is characterized by further containing a binder component.

In addition, "(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 containing fine particles made of an organic material or an inorganic material, a structural unit based on (meth) acrylic acid, and a structural unit based on (meth) acrylic acid salt. It can be produced by the production method of the present invention, which comprises a step of applying a coating liquid containing a polymer, a binder component, and a solvent to the surface of a substrate and drying it.

Further, the separator for a non-aqueous battery of the present invention is characterized in that the porous layer for a non-aqueous battery of the present invention is integrated with a porous resin sheet.

Further, the electrode for a non-aqueous battery of the present invention is characterized by having an electrode mixture layer containing an active material and having a porous layer for a non-aqueous battery of the present invention on the electrode mixture layer. Is.

Further, the non-aqueous battery of the present invention has (a) a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, and the separator is the separator for a non-aqueous battery of the present invention, or (b) a positive electrode and a negative electrode. , And a non-aqueous electrolyte, characterized in that at least one of the positive electrode and the negative electrode is the electrode for a non-aqueous battery of the present invention.

According to the present invention, there is a porous layer interposed between the positive electrode and the negative electrode of a non-aqueous battery, which can suppress the amount of water 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 having the separator and the electrode having the separator and the separator or the electrode, and capable of suppressing deterioration of characteristics due to moisture brought into the inside.

It is a vertical sectional view schematically showing an example of the non-aqueous battery of this invention.

As described above, a coating liquid (composition containing a solvent such as a slurry or paste) for forming a heat-resistant layer of a separator or a porous layer provided as an isolation layer interposed between a positive electrode and a negative electrode, particularly an aqueous system. In the coating liquid, a water-soluble resin having moisture absorption such as CMC is generally used as a thickener for adjusting the viscosity, which increases the amount of water brought into the non-aqueous battery. It causes and contributes to the deterioration of the characteristics of non-aqueous batteries.

As a result of diligent studies in order to suppress deterioration of the characteristics of non-aqueous batteries due to such reasons, the present inventors have conducted a coating liquid used for forming a porous layer provided on a separator, an electrode, or the like. As the thickener, it was decided to adopt an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylic acid salt. As a result, it becomes difficult for water to be contained in the formed porous layer, so that the amount of water brought into the non-aqueous battery can be reduced, and the resulting deterioration of characteristics can be suppressed.

The porous layer for a non-aqueous battery of the present invention (hereinafter, simply referred to as “porous layer”) includes fine particles composed of an organic material or an inorganic material, a structural unit based on (meth) acrylic acid, and (meth) acrylic acid. Includes acrylic acid-based polymers, including salt-based building blocks, and binder components.

In the porous layer of the present invention, the fine particles composed of an organic material or an inorganic material are caused by lithium dendrite by being the main component thereof or filling the voids formed between the fibrous substances described later. It has the effect of suppressing the occurrence of short circuits, and when 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 the heat resistant layer of the separator, the heat resistance of the separator is applied. It functions as an ingredient that enhances sex. Further, by forming the fine particles with a heat-meltable resin, for example, a resin having a melting point of 150 ° C. or lower, it is possible to impart a shutdown function to the porous layer.

Further, an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylic acid salt is used as a thickener for a coating liquid for forming a porous layer. It also remains in the formed porous layer. If the coating liquid uses the acrylic acid-based polymer as a thickener, it is possible to easily secure a viscosity sufficient to perform at least an appropriate coating operation even with a small amount of addition, and the porosity after formation is sufficient. The amount of water adsorbed is reduced in the layer as compared with the case of using a general thickener such as CMC or a water-soluble resin such as sodium polyacrylate which does not contain a structural unit based on (meth) acrylic acid. be able to.

In the present specification, "including a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylic acid salt" in the acrylic acid-based polymer forms a molecule of the acrylic acid-based polymer. As the structural unit, as shown in the following formula (1), one derived from (meth) acrylic acid (one in which the carboxyl group exists as it is) and (meth) as shown in the following formula (2). It means that the carboxyl group of acrylic acid is contained in a salt state. The structural unit in which the carboxyl group of (meth) acrylic acid is a salt is introduced into the molecule in the form of using a salt of (meth) acrylic acid as a monomer for polymerizing the acrylic acid-based polymer [that is,. It may be a 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 [a structural unit derived from (meth) acrylic acid in the polymer]. It may be introduced by neutralizing the carboxyl group of a part of the above.

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

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

Therefore, as the acrylic acid-based polymer containing the (meth) acrylic acid-based structural unit and the (meth) acrylic acid salt-based structural unit used for the porous layer, for example, in the part of the polyacrylic acid made of an alkali metal or the like. Japanese products, that is, some of the carboxyl groups (-COOH) in the acrylic acid-based structural unit of polyacrylic acid (polymer) are neutralized to alkali metal salts such as sodium salts [-COOM'(M). 'Is an alkali metal element)] is exemplified.

A completely neutralized product of polyacrylic acid (all of the carboxyl groups are alkali metal salts) easily absorbs water, and it is difficult to reduce the water content in a porous layer containing a certain amount of this. Therefore, the porous material of the present invention is used. In the layer (coating liquid for forming it), in an acrylic acid-based polymer containing (meth) acrylic acid-based structural units and (meth) acrylic acid salt-based structural units (eg, in a portion of polyacrylic acid). Japanese) is used.

The acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate is a structural unit based on (meth) acrylic acid and a constitution based on (meth) acrylate. A ternary system comprising a constituent unit other than the unit, and depending on the required properties, an ethylenically constituent unit, such as a constituent unit based on a monomer component such as acrylamide, acrylonitrile, N-vinylacetamide, etc. It is also possible to obtain the above polymer.

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

Further, the acrylic acid-based 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 effect of reducing the water content 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 degree of neutralization of the acrylic acid-based polymer is preferably 10% or more, more preferably 30% or more.

Neutralization degree = b ÷ (a + b) × 100

In order to make the acrylic acid-based polymer function as a thickener and to make the coating liquid containing the acrylic acid polymer have a viscosity higher than a certain level required for coating, the porous layer formed by drying the coating liquid is used. The content in the coating liquid may be adjusted so that the content in the coating liquid is 0.05% by mass or more, and the content of the acrylic acid-based polymer in the porous layer is 0.1% by mass. % Or more is preferable.

On the other hand, if the content of the acrylic acid-based polymer in the porous layer is too large, the viscosity of the coating liquid may become too high, and the water content in the formed porous layer becomes too large. , The effect of reducing the water content by using the acrylic acid-based polymer may be impaired. In order to prevent the above-mentioned problem, the content in the coating liquid may be adjusted so that the content of the acrylic acid-based polymer in the porous layer is 0.45% by mass or less, and the porosity may be prevented. The content of the acrylic acid-based polymer in the layer is preferably 0.3% by mass or less.

The thickener of the coating liquid includes an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylic acid salt, and other than the polymer, depending on the purpose. 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-based polymer include polyacrylic acid, sodium polyacrylate, and carboxymethyl cellulose.

However, in order to make it easy to adjust the viscosity of the coating liquid to a suitable range and to secure a better effect of reducing the water content in the porous layer, the content of the entire water-soluble resin in the porous layer It is desirable to adjust so that the amount of water is not too large, and for example, in the separator containing the porous layer, it is desirable to adjust so that the water content measured by the method described later is 1200 ppm or less. Specifically, the content of the entire water-soluble resin containing the acrylic acid-based polymer in the porous layer is preferably, for example, 0.5% by mass or less.

The acrylic acid-based polymer that functions as a thickener in the coating liquid has a low function as a binder, and sufficient adhesive strength cannot be obtained by itself. Therefore, in the present invention, a binder is further applied to the porous layer. Contains ingredients.

As the binder in the porous layer, an ethylene-vinyl acetate copolymer (EVA, one having a structural unit derived from vinyl acetate of 20 to 35 mol%), a (meth) acrylate polymer [“(meth) acrylate” is It is a collective expression of acrylate and methacrylate. same as below. ], Fluorine-based rubber, styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP), polyurethane, polyN-vinylacetamide, polyacrylamide, etc. As described above, in addition to those used in the form of aqueous emulsions, water-soluble resins 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 binder is too large, the content of other components (such as fine particles composed of organic or inorganic materials) may be reduced, and the action of these other components may be reduced, so that the composition is porous. The binder content in the layer is preferably 10% by mass or less.

The fine particles made of an organic material or an inorganic material related to the porous layer have an electrical insulating property, are electrochemically stable, and are a non-aqueous electrolyte described later and a coating liquid for forming a porous layer. As long as the solvent used for the above is stable, there is no particular limitation.

As used herein, "stable with respect to a non-aqueous electrolyte" means that it is soluble in a solvent or has a chemical composition in a non-aqueous electrolyte (a non-aqueous electrolyte such as a non-aqueous electrolyte used as an electrolyte of a non-aqueous battery). It means that it is difficult for changes to occur. "Stable to the solvent used in the coating liquid for forming a porous layer" has the same meaning as described above. Further, "electrochemically stable" as used herein means that a chemical change is unlikely to occur during charging and discharging of a battery.

The fine particles made of an inorganic material are preferably made 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, and as a specific example of such fine particles. For example, oxide fine particles such as iron oxide, SiO ₂ , Al ₂ O ₃ , TiO ₂ , BaTIO ₃ , ZrO ₂ , MgO; and nitride fine particles such as aluminum nitride and silicon nitride; calcium fluoride, barium fluoride. , Poorly soluble ion crystal particles such as barium sulfate; Covalently bonded crystal particles such as silicon and diamond; Clay particles such as talc and montmorillonite; Inorganic fine particles such as substances derived from mineral resources such as hydrotalcite or man-made products thereof; may be mentioned.

Further, as the fine particles made of an organic material, when the fine particles are made of a material having a heat resistant temperature of 150 ° C. or higher as in the case of the inorganic material, specific examples thereof include polyimide, melamine-based resin, phenol-based resin, and crosslinked poly. Examples thereof include cross-linked polymer fine particles such as methyl methacrylate (cross-linked PMMA), cross-linked polystyrene (cross-linked PS), polydivinylbenzene (PDVB), and benzoguanamine-formaldehyde condensate; and heat-resistant polymer fine particles such as thermoplastic polyimide. The organic resin (polymer) constituting these organic fine particles is a mixture, a modified product, a derivative, or a copolymer (random copolymer, alternate copolymer, block copolymer, graft copolymer) of the above-exemplified materials. ), A crosslinked body (in the case of the above-mentioned heat-resistant polymer).

On the other hand, when imparting a shutdown function to the porous layer, it is preferable to configure the fine particles with a heat-meltable resin having a melting point of 150 ° C. or lower so that the reaction of the battery can be suppressed at a safe temperature, and it is safe. It is more preferable that the melting point of the heat-meltable resin is 140 ° C. or lower in order to increase the temperature. Specific examples of such fine particles include PE, a copolymerized polyolefin having an ethylene-derived structural unit of 85 mol% or more, a polyolefin derivative (chlorinated polyethylene, etc.), a polyolefin wax, a petroleum wax, a carnauba wax, and the like. Be done. Examples of the copolymerized 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. can. Further, polycycloolefin and the like can also be used.

However, if the temperature at which shutdown occurs is too low, it may interfere with the operation of a normal battery. 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 by a differential scanning calorimeter (DSC) according to JIS K 7121.

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

When the porous layer contains fine particles of a heat-meltable resin having a melting point of 150 ° C. or lower to have a shut-down function, the heat-meltable resin in the porous layer is provided from the viewpoint of ensuring a good shutdown function. 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, fine particles of oxides or hydroxides such as SiO ₂ , Al ₂ O ₃ and boehmite are particularly preferable.

The form of the fine particles composed of an organic material or an inorganic material may be any form such as spherical, irregular shape, plate shape, polyhedral shape, secondary particle shape, needle shape, etc., but from the viewpoint of suppressing lithium dendrite. Therefore, it 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 SI Tech Co., Ltd., "NST-B1" crushed product (TiO ₂ ) manufactured by Ishihara Sangyo Co., Ltd., and Sakai Chemical Industry Co., Ltd. Plate-shaped barium sulfate "H series", "HL series", Hayashi Kasei "Micron White" (Tark), Hayashi Kasei "Bengel" (Bentnite), Kawai Lime "BMM" and "BMT" (Bemite), Kawai Lime Co., Ltd. "Cerasur BMT-B" [Alumina (Al ₂ O ₃ )], Kinsei Matek Co., Ltd. "Seraph" (Alumina), Hikawa Mining Co., Ltd. "Hikawa Mika Z-20" (Serisite) ) Etc. are available. In addition, SiO ₂ , Al ₂ O ₃ , ZrO, and CeO ₂ can be produced by the method disclosed in JP-A-2003-206475.

When the fine particles made of an organic material or an inorganic material are plate-shaped, it is preferable to orient the fine particles in the porous layer so that the flat plate surface thereof is substantially parallel to the surface of the porous layer. By using a separator having such a porous layer, it is possible to better suppress the occurrence of a short circuit in the battery. This is because the fine particles are arranged so as to overlap each other on a part of the flat plate surface by orienting the fine particles as described above, so that the voids (through holes) from one side to the other side of the porous layer are straight lines. It is thought that it is formed in a curved shape (that is, the winding ratio is increased), which can prevent the lithium dendrite from penetrating the porous layer, so that the occurrence of short circuit is better suppressed. It is presumed to be.

When the fine particles are plate-shaped particles, for example, the aspect ratio (ratio of the maximum length in the plate-shaped particles to the thickness of the plate-shaped particles) is 5 or more, more preferably 10 or more, and 100. Below, it is more preferably 50 or less. Further, the average value of the ratio of the length in the major axis direction to the length in the minor axis direction of the flat plate surface of the particles is preferably 0.3 or more, more preferably 0.5 or more (1, that is, the length in the major axis direction). And the minor axis length may be the same). When the plate-shaped fine particles have the aspect ratio and the average value of the ratio of the length in the major axis direction to the length in the minor axis direction of the flat plate surface as described above, the short circuit prevention action is more effectively exhibited.

When the fine particles are plate-shaped, the average value of the ratio of the length in the major axis direction to the length in the minor axis direction of the flat plate surface is, for example, an image analysis of an image taken by a scanning electron microscope (SEM). Can be obtained by. Further, the aspect ratio when the fine particles are plate-shaped can also be obtained by image analysis of the image taken by SEM.

The average particle size 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, and more preferably 1 μm or less.

For the average particle size of the fine particles made of the organic material or the inorganic material referred to in the present specification, for example, a laser scattering particle size distribution meter (for example, "LA-920" manufactured by HORIBA) can be used to dissolve the fine particles or the fine particles. It can be specified as a 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 obtained 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 even more preferably 30 m ² / g or less. If the specific surface area is too large, the amount of binder for binding the fine particles to each other or the fine particles to the base material or the electrode becomes too large, so that the output characteristics of the battery may deteriorate, and the particles are adsorbed on the surface of the fine particles. There is a possibility that the amount of water to be added increases, and the effect of suppressing deterioration of the characteristics of the non-aqueous battery due to the use of the acrylic acid-based polymer becomes small. On the other hand, a suitable lower limit of the specific surface area of the fine particles is 1 m ² / g. The specific surface area referred to here is a value measured by the BET method using nitrogen gas.

Further, in the porous layer of the present invention, when the above-mentioned fine particles having a high heat resistance of 150 ° C. or higher are used, the action thereof suppresses heat shrinkage at high temperature and enhances dimensional stability. Can be done. Further, when the porous layer of the present invention containing fine particles having a high heat resistance of 150 ° C. or higher is integrated with the electrode (positive electrode or negative electrode), the dimensions of the porous layer at high temperature are high. Stability can be further enhanced.

Further, even when the separator is composed of a porous layer containing highly heat-resistant fine particles having a heat-resistant temperature 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 shrinkage of the porous resin sheet is suppressed because it is integrated with the porous layer with good dimensional stability at high temperatures due to the action of fine particles with a heat resistant temperature of 150 ° C or higher, and at high temperatures. The dimensional stability of the entire separator is improved. Therefore, in the present invention, by constructing the separator using the porous layer having high dimensional stability, for example, the separator composed only of the conventional porous film made of polyethylene (PE) (microporous film made of PE). Since it is possible to prevent the occurrence of a short circuit due to the heat shrinkage that has occurred, it is possible to further improve the reliability and safety when the inside of the battery is abnormally overheated.

As described above, according to one embodiment of the present invention, the reliability of preventing a short circuit due to thermal shrinkage of the separator at high temperature can be improved.

The porous layer may contain a fibrous material having a heat resistant temperature of 150 ° C. or higher. For example, when the separator is composed of only the porous layer and the porous layer is not integrated with the electrode, the fibrous material is contained from the viewpoint of reinforcing the porous layer and improving its handleability. It is preferable, and it is more preferable that this fibrous material forms the main component of the separator. Further, even when the separator is composed of the porous layer and the porous resin film, or when the porous layer is integrated with the electrode, a fibrous material having a heat resistant temperature of 150 ° C. or higher is contained to reinforce the separator. be able to.

In particular, the porous layer contains a material that can be melted at a temperature of 140 ° C. or lower to close the pores of the porous layer (separator) and impart a function of blocking the movement of ions in the separator (so-called shutdown function). In this case, by including a fibrous material having a heat resistant temperature of 150 ° C. or higher in the porous layer, even if the temperature of the separator rises further by 20 ° C. or higher after shutdown occurs due to heat generation in the battery or the like. , The shape can be kept more stable.

The fibrous material has a heat resistant temperature of 150 ° C. or higher, has an electric insulating property, is electrochemically stable, and is a non-aqueous electrolyte (non-aqueous electrolyte solution) described in detail below, or an organic substance. There is no particular limitation as long as the solvent used for the coating liquid for forming a porous layer containing fine particles composed of a material or an inorganic material is stable. The term "fibrous material" as used herein means a material having an aspect ratio [length in the long direction / width (diameter) in the direction orthogonal to the long 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, a cellulose modified product (carboxymethyl cellulose, etc.), polypropylene (PP), polyester [polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT). ) Etc.], resins such as polyacrylonitrile (PAN), aramid, polyamideimide, and polyimide; inorganic materials such as glass, alumina, and silica (inorganic oxides); and the like. The fibrous material may contain one of these constituent materials, or may contain two or more of them. In addition to the above-mentioned constituent materials, the fibrous material may contain various known additives (for example, an antioxidant in the case of a resin), if necessary. do not have.

The fibrous material may be subjected to surface treatment such as corona discharge treatment or treatment with a surfactant in order to enhance the adhesiveness with fine particles composed of an organic material or an inorganic material.

The diameter of the fibrous material may be not less than or equal to the thickness of the porous layer, but is preferably 0.01 to 5 μm, for example. If the diameter is too large, the entanglement of the fibrous materials may be insufficient, and the strength of the sheet-like material composed of these, and thus the strength of the porous layer, may be reduced, which may make handling difficult. Further, if the diameter is too small, the pores of the porous layer become too small, and the ion permeability tends to decrease, which may deteriorate the load characteristics of the battery.

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

That is, a porous layer for a non-aqueous battery is formed so as to fill the voids of a porous resin sheet such as a non-woven fabric, and the porous resin sheet is integrated and exists in the porous layer. May be good.

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

The content of the fine particles composed of the organic material or the inorganic material in the porous layer is the composition of the porous layer from the viewpoint of more effectively exerting the action by using the fine particles composed of the organic material or the inorganic material. It may be 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more, based on the total mass of the components.

Further, when the porous layer contains the above-mentioned fibrous material, the content of the fibrous material in the porous layer is a constitution of the porous layer from the viewpoint of more effectively exerting the action by using the fibrous material. The total volume of the components is preferably 10% by volume or more, more preferably 30% by volume or more. On the other hand, if the content of the fibrous material is too large in the porous layer containing the fibrous material, the content of other components (fine particles composed of an organic material or an inorganic material, etc.) is reduced. Since the action of these other components may be reduced, the content of the fibrous material is preferably 90% by volume or less, preferably 70% by volume or less, based on 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, and 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 by using the following formula (3).
P = 100- (Σa _i / ρ _i ) × (m / t) (3)

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

The porous layer of the present invention is an acrylic acid-based 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) acrylic acid salt. Further, a coating liquid (composition containing a solvent) for forming a porous layer containing a fibrous substance or the like used as needed is applied to the surface of a substrate, for example, a porous resin sheet (non-invention of the present invention). The manufacturing method of the present invention comprising a step of applying to the surface of the electrode mixture layer of the electrode for a non-water battery (when the separator for a water battery is used) and drying. Can be obtained by

Further, when producing a separator in which the porous layer is integrated with a porous resin sheet (woven fabric, non-woven fabric, etc.) made of a fibrous material, for example, the coating liquid is not used for coating but is used as an immersion liquid. The sheet-like material is impregnated therein, and if necessary, the immersion liquid is passed through a gap to promote the penetration of the immersion liquid into the voids of the sheet-like material, or the coating liquid is applied to the sheet-like material. After that, the coating liquid may be allowed to penetrate into the voids of the sheet-like material through a gap, and then dried to form a porous layer.

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 a fibrous substance used as needed, and these are used as a solvent containing water (including a dispersion medium; the same applies hereinafter). ) Is dissolved or dispersed. Normally, an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid, which is a thickener, and a structural unit based on (meth) acrylic acid salt are dissolved in the solvent, and a binder component is also contained. It can also be dissolved in a solvent. Although only water may be used as the solvent used in the coating liquid, each of the fine particles may be uniformly dispersed, the acrylic acid-based polymer may be satisfactorily dissolved, or the binder component may be uniformly dissolved. A solvent other than water such as alcohols (methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, etc.) can be appropriately added for the purpose of dispersing and controlling the interfacial tension.

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

The separator for a non-aqueous battery of the present invention (hereinafter, simply referred to as "separator") is one in which the porous layer of the present invention is integrated 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 film made of polyolefin, the resin constituting the porous resin film comprises the above-mentioned heat-meltable fine particles. A resin (thermoplastic resin) similar to 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 lower. Therefore, the thermoplastic resin constituting the porous resin film also has a melting point of 100 to 150. It is desirable to use one having a temperature of ° C, and it is more preferable to keep the temperature at 140 ° C or lower.

On the other hand, when the heat resistance of the separator is emphasized and the shutdown function is not provided, a heat-resistant porous resin sheet can also be used. As a specific constituent material of such a porous resin sheet, a heat resistant temperature of 150 ° C. or higher is stable against a non-aqueous electrolytic solution used in a battery, and further stable against a redox reaction inside the battery. Any resin may be used. More specifically, heat-resistant resins such as polyimide, polyamide-imide, aramid, polytetrafluoroethylene, polysulfone, polyurethane, PAN, and polyester (PET, PBT, PEN, etc.) can be mentioned.

The porous resin sheet is, for example, a porous film composed of the above-exemplified resin used in a conventionally known non-aqueous battery or the like, that is, an ion produced by a solvent extraction method, a dry method, a wet stretching method, or the like. A permeable porous film (microporous film), a woven fabric, a fibrous sheet such as a non-woven fabric can be used. Further, a film microporous by a foaming method using a chemical or supercritical CO ₂ can also be used.

In the separator of the present invention, good heat resistance (heat shrinkage) can be ensured even if a material that easily shrinks heat is applied to the porous resin sheet by the action of the porous layer of the present invention. Therefore, for example, It is preferable to use 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, the porous layer and the porous resin sheet do not have to be one layer each, and one or both of them may be two or more layers, but the number of layers of the separator is increased too much. Is not preferable, and 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 further 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. It is more preferably 5 μm or more. On the other hand, from the viewpoint of further increasing the energy density of the non-aqueous 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.

When 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, it should be 5 μm or more in the case of the porous resin film. Is preferable, and 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 preferable thickness of the porous layer described above.

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

The porosity of the separator is preferably 20% or more, preferably 30% or more, in a dry state in order to secure the retention amount of the non-aqueous electrolytic solution and improve the ion permeability. Is more preferable. On the other hand, from the viewpoint of ensuring the strength of the separator and preventing internal short circuits, the porosity of the separator is preferably 70% or less, more preferably 60% or less in a dry state. For the porosity of the separator: P (%), in the above formula (3), m is the mass per unit area of the separator (g / cm ² ), and t is the thickness of the separator (cm). , Can be obtained using the above formula (3).

Further, in the above formula (3), m is the mass per unit area of the porous resin sheet (g / cm ² ), and t is the thickness (cm) of the porous resin film. The porosity of the porous resin sheet: P (%) can also be determined by using. The porosity of the porous resin sheet obtained by this method is preferably 30 to 70%.

Further, as the strength of the separator, it is desirable that the piercing strength using a needle having a diameter of 1 mm is 50 g or more. If the piercing strength is too small, a short circuit may occur due to the piercing of the separator when lithium dendrite crystals are generated.

The air permeability of the separator was measured by a method according to JIS P 8117, and the Garley value, which is the number of seconds that 100 ml of air permeates the membrane under a pressure of 0.879 g / mm ² , is 10 to 300 sec. It is desirable to have. If the air permeability is too large, the ion permeability may be small, and if it is too small, the strength of the separator may be small.

Further, it is desirable that the Garley value of the separator satisfies the relationship of the following equation (4).
Gs ≤ max {Ga, Gb} +10 (4)

In the above formula (4), Gs: the gallium value of the separator, Ga: the gallium value of the porous resin film, the gallium value of the porous layer of the present invention, max {a, b}: a or b, whichever is larger. be. However, Gb is obtained by using the following formula (5).
Gb = Gs-Ga (5)

The piercing strength and air permeability can be ensured by using the separator having the structure described above.

The electrode for a non-aqueous battery 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 electrodes of the present invention are used for the positive electrode or the negative electrode of a non-aqueous battery. The batteries in which the electrodes of the present invention are used include non-aqueous primary batteries and non-aqueous secondary batteries, and the following are the main non-aqueous secondary batteries as batteries in which the electrodes of the present invention are used. The details of the electrode having a configuration suitable for the above will be described.

As the electrode of the present invention when used for the positive electrode of a non-aqueous battery, for example, an electrode mixture layer (positive electrode mixture layer) containing a positive electrode active material, a conductive auxiliary agent, a binder and the like is provided on one side of a current collector. Alternatively, a structure having both sides and having a porous layer of the present invention formed on these electrode mixture layers can be mentioned.

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. Examples thereof include a spinnel-structured lithium-containing composite oxide such as _{5/3 O4 ; an olivine-structured lithium-containing composite oxide such as LiFePO 4 ;} an oxide having the above oxide as a basic composition and substituted with various elements; and the like. Only one of these may be used, or two or more thereof may be used in combination.

Conductive auxiliaries related to the positive electrode mixture layer include, for example, natural graphite (scaly graphite, etc.), graphite such as 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 fluoride; metal powders such as aluminum; zinc oxide; conductivity such as potassium titanate. Sexual 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), polyvinylpyrrolidone (PVP) and the like.

For the positive electrode, for example, a positive electrode mixture containing a positive electrode active material, a conductive auxiliary agent, a binder, etc. is dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP) or water to form a paste-like or slurry-like positive electrode. An agent-containing composition is prepared (however, the binder may be dissolved in a solvent), which is applied to one or both sides of the current collector, dried, and then subjected to calendar treatment as necessary, and further subjected to this. It can be produced through the steps of forming the porous layer of the present invention on the positive electrode mixture layer using the positive electrode as a base material by the above method. However, the positive electrode is not limited to the one manufactured by the above method, and may be manufactured by another method.

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.

Further, a lead body for electrically connecting to other members in the non-aqueous battery may be formed on the positive electrode according to a conventional method, if necessary.

As for the composition of the positive electrode mixture layer, for example, the content of the positive electrode active material is preferably 80.0 to 99.8% by mass, and the content of the conductive auxiliary agent is 0.1 to 10% by mass. The binder content is preferably 0.1 to 10% by mass. The thickness of the positive electrode mixture layer is preferably 1 to 100 μm per one side of the current collector.

When used as a negative electrode of a non-aqueous battery, the electrode of the present invention includes, for example, an electrode mixture layer (negative electrode mixture layer) containing a negative electrode active material, a binder, and, if necessary, a conductive auxiliary agent. , A structure having a current collector on one side or both sides and having a porous layer of the present invention formed on these electrode mixture layers can be mentioned.

The negative electrode active material may be any material that can be doped and dedoped with lithium ions, for example, graphite, pyrolytic carbons, cokes, glassy carbon, calcined organic polymer compounds, mesocarbon microbeads, and carbon. Examples include carbonaceous materials such as fiber and activated carbon. Further, 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, and the like, as well as lithium-aluminum and lithium-lead. , Lithium-indium, lithium-gallium, lithium-indium-gallium, and the like. Some of these exemplified negative electrode active materials do not contain lithium at the time of manufacture, but they are in a state of containing lithium at the time of charging.

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

When the negative electrode mixture layer contains a conductive auxiliary agent, the same conductive auxiliary agent as the various conductive auxiliary agents exemplified above can be used as the conductive auxiliary agent for the positive electrode mixture layer.

The negative electrode has a negative electrode mixture-containing composition in the form of a paste or slurry by dispersing, for example, a negative electrode active material, a binder, and a negative electrode mixture containing a conductive auxiliary agent as necessary in a solvent such as NMP or water. A product is prepared (however, the binder may be dissolved in a solvent), this is applied to one or both sides of the current collector, dried, and then subjected to calendar treatment as necessary, and further based on this negative electrode. As a material, it can be produced through the step of forming the porous layer of the present invention on the negative electrode mixture layer by the above method. However, the negative electrode is not limited to the one manufactured by the above method, and may be manufactured by another method.

For the current collector of the negative electrode, for example, a foil made of copper, stainless steel, nickel, titanium or an alloy thereof, punched metal, expanded metal, net, etc. can be used, but copper having a thickness of 5 to 30 μm is usually used. Foil is preferably used.

Further, a lead body for electrically connecting to other members in the non-aqueous battery may be formed on the negative electrode according to a conventional method, if necessary.

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. When a conductive auxiliary agent is used, the content of the conductive auxiliary agent in the negative electrode mixture layer is preferably 1 to 20% by mass. Further, the thickness of the negative electrode mixture layer is preferably 1 to 100 μm per one side of the current collector.

The non-aqueous battery of the present invention has a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, and the separator is the separator of the present invention or has a positive electrode, a negative electrode and a non-aqueous electrolyte, and the positive electrode and the negative electrode. At least one of them may be the electrode of the present invention, and the other configurations and structures are not particularly limited. , Non-aqueous primary batteries) can be applied with various configurations and structures.

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

In the non-aqueous battery of the present invention, the positive electrode and the negative electrode are laminated with a separator interposed therebetween, or the porous layer formed on at least one electrode mixture layer is laminated so as to be in between. It is used in the form of a laminated body (laminated electrode body) or a wound body (wound electrode body) in which the laminated body is wound in a spiral shape.

As the non-aqueous electrolyte of the non-aqueous battery, as described above, a solution (non-aqueous electrolyte solution) 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 side reactions such as decomposition in the 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 [Here, R _f is a fluoroalkyl group] and other organic lithium salts; Can be used.

The organic solvent used for the non-aqueous electrolytic solution is not particularly limited as long as it dissolves the above-mentioned lithium salt and does not cause a side reaction such as decomposition in the voltage range used as a battery. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate; chain esters such as dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate; chain esters such as methyl propionate; cyclic esters such as γ-butylolactone; dimethoxy. Chained ethers such as ethane, diethyl ether, 1,3-dioxolane, diglime, triglime, tetraglyme; cyclic ethers such as dioxane, tetrahydrofuran, 2-methyltetraoxide; nitriles such as acetonitrile, propionitrile, methoxypropionitrile; Examples thereof include sulfite esters such as ethylene glycol sulfite; and the like, and these may be used alone or in combination of two or more. In order to obtain a battery having better characteristics, it is desirable to use a combination such as a mixed solvent of ethylene carbonate and chain carbonate, which can obtain high conductivity. In addition, for the purpose of improving the properties of these non-aqueous electrolytes such as safety, charge / discharge cycle property, and high temperature storage property, vinylene carbonates, 1,3-propanesalton, diphenyl disulfide, cyclohexylbenzene, biphenyl, and fluorobenzene. , T-butylbenzene and other additives can be added as appropriate.

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

Further, instead of the above-mentioned organic solvent, room temperature melting such as ethyl-methylimidazolium trifluoromethyl sulfonium imide, heptyl-trimethylammonium trifluoromethyl sulfonium imide, pyridinium trifluoromethyl sulfonium imide, guadinium trifluoromethyl sulfonium imide is used. Salt can also be used.

Further, a polymer material containing the non-aqueous electrolyte solution and gelling may be added to make the non-aqueous electrolyte solution into a gel state (gel-like electrolyte) for use in a battery. Examples of the polymer material for gelling the non-aqueous electrolyte solution include PVDF, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), PAN, polyethylene oxide, polypropylene oxide, and ethylene oxide-propylene oxide copolymer. Examples thereof include known host polymers capable of forming a gel-like electrolyte, such as a crosslinked polymer having an ethylene oxide chain in the main chain or a side chain, and a crosslinked poly (meth) acrylic acid ester.

Examples of the non-aqueous battery of the present invention include a tubular shape (square tubular shape, cylindrical shape, etc.) using a steel can, an aluminum can, or the like as an outer can. Further, a soft package battery having a laminated film on which metal is vapor-deposited as an exterior body can also be used.

The non-water battery of the present invention can be applied to the same applications as a non-water secondary battery such as a conventionally known lithium secondary battery and a non-water primary battery.

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

Example 1
<Manufacturing of positive electrode>
To 90 parts by mass of LiCoO ₂ : which is a positive electrode active material, 5 parts by mass of carbon black which is a conductive auxiliary agent is added and mixed, and a solution in which 5 parts by mass of PVDF which is a binder is dissolved in NMP is added to this mixture. And mixed to obtain a positive electrode mixture-containing slurry, which was passed through a 70-mesh net to remove those having a large particle size. This positive electrode mixture-containing slurry is uniformly applied to both sides of a positive electrode current collector made of 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, and then cut. , An aluminum lead body was welded to the exposed part of the current collector to prepare a strip-shaped positive electrode.

<Manufacturing 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 paste containing a negative electrode mixture. This negative electrode mixture-containing paste is uniformly applied to both sides of a negative electrode current collector made of a copper foil having a thickness of 10 μm, dried, and then compression-molded by a roll press to make the total thickness 100 μm, and then cut. A nickel lead body was welded to the exposed portion of the current collector to prepare a band-shaped negative electrode.

<Preparation of non-aqueous electrolyte solution>
In a mixed solvent of ethylene carbonate, methyl ethyl carbonate and diethyl carbonate in 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 solution. The non-aqueous electrolyte solution was prepared by adding the mixture in an amount of 2.5% by volume.

<Making a separator>
Add 4000 g of boehmite powder (plate-shaped, average particle size: 1 μm, aspect ratio: 10, specific surface area: 8 m ² / g), which is a fine particle having a heat resistant temperature of 150 ° C. or higher, to water: 4000 g in 4 portions. A uniform slurry was prepared by stirring with a disper at 2800 rpm for 5 hours. In this slurry, SBR (solid content 50%) as a binder: 400 g and a partially neutralized sodium polyacrylic acid as a thickener [Showa Denko "Viscomate NP-800" (trade name), degree of neutralization: 35%] 1.5% aqueous solution: 267 g was added, and water was further added and stirred at room temperature until uniformly dispersed. A slurry for forming a porous layer (coating liquid) having a solid content concentration of 35% by mass was added. ) Was prepared.

The slurry for forming a porous layer is applied by a microgravure coater on the treated surface of a PE microporous membrane (thickness: 16 μm, porosity: 40%, PE melting point: 135 ° C.) whose one surface is treated with corona discharge. Then, it was dried to form a porous layer to obtain a separator having a thickness of 20 μm.

<Battery assembly>
The separators obtained as described above were stacked while being interposed between the positive electrode and the negative electrode so that the porous layer faces the positive electrode side, and wound in a spiral shape to prepare a wound electrode body. The obtained wound electrode body was placed in an iron outer can (battery case) having a diameter of 18 mm and a height of 65 mm, and after injecting a non-aqueous electrolytic solution, sealing was performed to create a non-water structure shown in FIG. A secondary battery was manufactured.

Here, the battery shown in FIG. 1 will be described. In the non-aqueous secondary battery shown in FIG. 1, a positive electrode 1 and a negative electrode 2 are spirally wound via a separator 3 and are non-aqueous electrolyzed as a wound electrode body. It is housed in the battery case 5 together with the liquid 4. In addition, in FIG. 1, in order to avoid complication, the current collector used for manufacturing the positive electrode 1 and the negative electrode 2 is 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 arranged on the bottom thereof prior to the insertion of the wound electrode body. The sealing plate 7 is made of aluminum and has a disk shape, a thin-walled portion 7a is provided in the center thereof, and a pressure introduction port 7b for applying the battery internal pressure to the explosion-proof valve 9 around the thin-walled portion 7a. Is provided with a hole. Then, the protruding portion 9a of the explosion-proof valve 9 is welded to the upper surface of the thin-walled portion 7a to form the welded portion 11. For the thin-walled portion 7a provided on the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9, only the cut surface is shown for easy understanding on the drawing, and the contour behind the cut surface is shown. Illustration is omitted. Further, 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 shown in an exaggerated state so as to be easy to understand on the drawing.

The terminal plate 8 is made of rolled steel and has a nickel-plated surface, and has a cap shape with a brim-shaped peripheral edge. 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 protruding portion 9a having a tip on the power generation element side (lower side in FIG. 1) is provided at the center thereof, and a thin-walled portion 9b is provided. The lower surface of the protruding portion 9a is welded to the upper surface of the thin-walled portion 7a of the sealing plate 7 as described above to form the welded portion 11. The insulating packing 10 is made of PP and has an annular shape. It is arranged on the upper part of the peripheral edge of the sealing plate 7, and the explosion-proof valve 9 is arranged on the upper part thereof to insulate the sealing plate 7 and the explosion-proof valve 9. , The gap between the two is sealed so that the non-aqueous electrolytic solution 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 arranged on the upper part of the wound electrode body, and the negative electrode 2 and the battery case 5 are arranged. It is connected to the bottom by a lead body 15 made of nickel.

In this non-water secondary battery, the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 come into contact with each other at the welded portion 11, and the peripheral edge portion of the explosion-proof valve 9 and the peripheral edge portion of the terminal plate 8 come into contact with each other. Since the positive electrode 1 and the sealing plate 7 are connected by the lead body 13 on the positive electrode side, under normal conditions, 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. An electrical connection is obtained by the portion 11 and functions normally as an electric circuit.

When an abnormal situation occurs in the battery such as the battery being exposed to a high temperature and gas is generated inside the battery to increase the internal pressure of the battery, the increase in the internal pressure causes the central portion of the explosion-proof valve 9 to move in the internal pressure direction. (In FIG. 1, it is deformed in the upper direction), and a shearing force acts on the thin-walled portion 7a integrated with the welded portion 11 to break the thin-walled portion 7a, or the protruding portion of the explosion-proof valve 9 is formed. After the welded portion 11 between the 9a and the thin-walled portion 7a of the sealing plate 7 is peeled off, the thin-walled portion 9b provided on the explosion-proof valve 9 is torn and gas is discharged to the outside of the battery from the gas discharge port 8a of the terminal plate 8. It is designed to prevent the battery from exploding.

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

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 an aqueous solution having a concentration of 1.5% of a partially neutralized sodium polyacrylate was added. Then, a non-aqueous secondary battery was produced in the same manner as in Example 1 except that the above separator was used.

Example 3
In the preparation of the slurry for forming the porous layer, the thickener was changed to a partially neutralized product of polyacrylic acid having a neutralization degree of 50% [Showa Denko's "Viscomate NP-700" (trade name)]. Made a separator having a thickness of 20 μm in the same manner as in Example 2. Then, a non-aqueous secondary battery was produced in the same manner as in Example 2 except that the above separator was used.

Example 4
Instead of the PE microporous membrane, a microporous membrane in which a PP layer and a PE layer are laminated in the order of PP / PE / PP (thickness: 16 μm, pore ratio: 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. Then, a non-aqueous secondary battery was produced in the same manner as in Example 1 except that the above separator was used.

Comparative Example 1
In the preparation of the slurry for forming a porous layer, 2000 g of a 2% aqueous solution of CMC (Daicel "2200") was added instead of the 1.5% aqueous solution of a partially neutralized sodium polyacrylate. A separator having a thickness of 20 μm was prepared in the same manner as in Example 1 except for the above. Then, a non-aqueous secondary battery was produced in the same manner as in Example 1 except that the above separator was used.

Comparative Example 2
In the preparation of the slurry for forming a 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 an aqueous solution having a concentration of 1.5% of a partially neutralized sodium polyacrylate was added. Then, a non-aqueous secondary battery was produced in the same manner as in Example 1 except that the above separator was used.

Comparative Example 3
In the preparation of the slurry for forming a porous layer, a slurry for forming a porous layer was prepared in the same manner as in Example 1 except that 80 g of an aqueous solution having a concentration of 1.5% of a partially neutralized sodium polyacrylic acid was added. When applied on a microporous film made of PE, the viscosity of the slurry was low, and a homogeneous separator could not be produced. Therefore, 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 as in Example 1 except that the thickener was changed to a completely neutralized sodium polyacrylate [(Showa Denko's "Viscomate F480SS" (trade name)]]. A separator having a thickness of 20 μm was produced, and a non-aqueous secondary battery was produced in the same manner as in Example 1 except that the above-mentioned 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 (a polymer not neutralized). When it was prepared and applied on a PE microporous film, the viscosity of the slurry was low and a homogeneous separator could not be produced. Therefore, the separator and the non-aqueous secondary battery using the separator were not evaluated.

The viscosities of the slurry for forming a porous layer prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were measured under the following conditions.

(Measurement of viscosity of slurry for forming porous layer)
The viscosity of each porous layer forming slurry was measured using an E-type viscometer (VISCONIC ED type) manufactured by Tokyo Keiki Co., Ltd. in an environment of 25 ° C. with a cone of 1 ° 34'and a rotation speed of 1 R. P. M. It was measured at (slip speed 3.83s ^-1 ).

In addition, the water content of the separators prepared in Examples 1 to 4 and Comparative Examples 1, 2 and 4 was measured under the following conditions.

(Measurement of water content of separator)
After each separator was allowed to stand in a glove box having a dew point of −50 ° C. for 12 hours or more, the measurement sample was placed in a heating furnace at 150 ° C. in which nitrogen gas was flown and held for 1 minute. After that, the flowed nitrogen gas was introduced into the measuring cell of the Karl Fischer Moisture Meter for each separator, and the water content was measured. The water content is measured in a glove box with a dew point of -50 ° C, and the water content of each separator is calculated by dividing the above measured value by the mass of the separator sample, using the integrated value up to the titration end point as the contained water content (mass standard). did.

Furthermore, the charge / discharge characteristics of the non-aqueous 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-water secondary batteries)
For each non-aqueous secondary battery, constant current charging is performed at a current value of 0.2C until the battery voltage reaches 4.2V, and then constant current-constant voltage charging is performed for constant voltage charging at 4.2V. rice field. The total charging time until the end of charging was 15 hours. Then, the charge capacity of each battery at that time was measured. Next, each battery after charging was discharged with a discharge current of 0.2 C until the battery voltage reached 3.0 V, and the discharge capacity was measured. Then, for each battery, the ratio of the discharge capacity to the charge capacity was expressed as a percentage to obtain the charge / discharge efficiency.

Table 1 shows the composition 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 results of each of the above measurements and evaluations.

As shown in Tables 1 and 2, a slurry for forming a porous layer using the acrylic acid-based polymer as a thickener was used, and a separator having an appropriate content of the acrylic acid-based polymer in the porous layer was used. Since the non-aqueous secondary batteries of Examples 1 to 4 have a low water content in the separator, the charge / discharge efficiency is very close to 100%, and it has been confirmed that the batteries operate well.

On the other hand, the batteries of Comparative Examples 1, 2 and 4 used a separator having a large amount of water content due to the thickener contained in the porous layer, so that the charge / discharge efficiency was low and the water content was high. Gas generation due to the influence of

1 Positive electrode 2 Negative electrode 3 Separator 4 Non-aqueous electrolyte

Claims (11)

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, and the content is 50% by mass or more.
The water-soluble resin contains an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylate.
The acrylic acid-based polymer has a structural unit (a) based on the (meth) acrylic acid, a structural unit (b) based on the (meth) acrylic acid salt, and the structural unit (a) and the structural unit (b). When the number of moles of the structural unit (c) other than the above is a, b and c, respectively, the degree of neutralization obtained from the following formula is 30% or more and 70% or less, and is represented by c / (a + b + c). The value is 0.3 or less,
Neutralization degree (%) = b ÷ (a + b) × 100
The total content of the water-soluble resin is 0.5% by mass or less, and the content is 0.5% by mass or less.
The content of the acrylic acid-based polymer is 0.05 to 0.45% by mass, and the content is 0.05 to 0.45% by mass.
Further, a porous layer for a non-aqueous battery, which is 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. The porous layer for a non-aqueous battery according to claim 1 or 2 , wherein the acrylic acid-based polymer is a partially neutralized product of polyacrylic acid. The porous layer for a non-aqueous battery according to any one of claims 1 to 3 , wherein the fine particles are fine particles of an oxide or a hydroxide. The porous layer for a non-aqueous battery according to any one of claims 1 to 4 , wherein the binder content is 0.5 to 10% by mass. The method for producing a porous layer for a non-aqueous battery according to any one of claims 1 to 5 .
It contains fine particles composed of an organic material or an inorganic material, an acrylic acid-based polymer containing a structural unit based on (meth) acrylic acid and a structural unit based on (meth) acrylic acid salt, a binder component, and a solvent. A method for producing a porous layer for a non-aqueous battery, which comprises a step of applying a coating liquid to the surface of a base material and drying it. A separator for a non-aqueous battery, wherein the porous layer for a non-aqueous battery according to any one of claims 1 to 5 is integrated with a porous resin sheet. The separator for a non-aqueous battery according to claim 7 , wherein the porous resin sheet is a microporous polyolefin membrane. An electrode for a non-aqueous battery, comprising an electrode mixture layer containing an active material, and having the porous layer for a non-aqueous battery according to any one of claims 1 to 5 on the electrode mixture layer. .. A non-aqueous battery comprising a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, wherein the separator is the separator for a non-aqueous battery according to claim 7 or 8 . A non-aqueous battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein at least one of the positive electrode and the negative electrode is the electrode for a non-aqueous battery according to claim 9 .

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