Separators for electrochemical elements, electrochemical elements and their manufacturing methods

Abstract

This invention provides a separator for an electrochemical element capable of bonding to an electrode without heating, an electrochemical element having the above-mentioned separator, and a method for manufacturing the same. The separator for the electrochemical element of this invention is characterized by comprising: a substrate layer formed of a porous membrane; and an adhesive layer for bonding to the electrode of the electrochemical element, wherein the adhesive layer contains a particulate resin (A) having a melting point of 75°C to 140°C, and the area weight of the resin (A) in the adhesive layer is 0.05 g / m². 2 The electrochemical element of the present invention is characterized in that it has a separator for electrochemical elements of the present invention, and at least one of the positive and negative electrodes is bonded to the separator by an adhesive layer provided by the separator.

Description

Technical Field

[0001] The present invention relates to a separator for an electrochemical element that can be bonded to an electrode without heating, an electrochemical element having the above-mentioned separator, and a method for manufacturing the same. Background Technology

[0002] In electrochemical elements, such as secondary batteries, various improvements have been made to achieve high capacity, such as increasing the functionality of the application equipment. However, in order to improve the safety and stability of the characteristics of electrochemical elements, the separator between the positive and negative electrodes is also frequently improved.

[0003] For example, Patent Document 1 proposes a separator containing a thermoplastic resin (B) with a melting point 40-60°C lower than that of thermoplastic resin (A) on the surface of a substrate with a thickness of 25 μm or less, primarily composed of a thermoplastic resin (A) with a melting point of 150-170°C. According to this separator, for example, when the temperature inside the electrochemical element rises excessively, the thermoplastic resin (B) with the lower melting point melts, causing the pores of the substrate to close. Therefore, the shape of the substrate primarily composed of the thermoplastic resin (A) with a higher melting point is maintained until the current value inside the electrochemical element reliably decreases. Thus, according to the separator described in Patent Document 1, the occurrence of internal short circuits can be effectively suppressed, and an electrochemical element with excellent safety can be constructed.

[0004] Furthermore, in the separator described in Patent Document 1, from the viewpoint of effectively closing the thermoplastic resin (B), the suitable unit area weight of the thermoplastic resin (B) is set to 1 g / cm³. 2 above.

[0005] Furthermore, in electrochemical devices, it is preferable to maintain the distance between the positive and negative electrodes to a certain extent in order to ensure stable performance during use. However, the electrodes of electrochemical devices undergo volume changes due to discharge and charging, resulting in a problem where the distance between the positive and negative electrodes deviates over time.

[0006] As a means of avoiding such problems, for example, Patent Document 2 proposes the following solution: an adhesive resin that exhibits adhesiveness upon heating is disposed on the surface of the separator, and the separator and the electrode are integrated by the adhesive resin.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2014-179165 (Scope of the technical solution, paragraphs

[0014] ,

[0015] ,

[0035] , etc.)

[0010] Patent Document 2: Japanese Patent Application Publication No. 2011-23186 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, when bonding separators to electrodes using adhesive resins, as described in Patent Document 2, the process is typically carried out while the adhesive resin is being heated to melt or soften it. However, in heat-based bonding, if the heat is not sufficiently transferred to the entire adhesive resin, the adhesion between the separator and the electrode cannot be adequately ensured, thus requiring a certain amount of time for the bonding process. However, for example, in the mass production of electrochemical devices, it is preferable to perform the bonding process between the separator and the electrode continuously to minimize the time spent bonding each part. Therefore, there is a need to develop a technology that can bond separators and electrodes well without heating them.

[0013] The present invention was made in view of the above circumstances, and its object is to provide a separator for an electrochemical element that can be bonded to an electrode without heating, an electrochemical element having the above separator, and a method for manufacturing the same.

[0014] Solution for solving the problem

[0015] The separator for electrochemical elements of the present invention is characterized by comprising: a substrate layer formed of a porous membrane; and an adhesive layer for bonding to the electrodes of the electrochemical element, wherein the adhesive layer contains a particulate resin (A), the resin (A) having a melting point of 75°C to 140°C, and the resin (A) in the adhesive layer having a unit area weight of 0.05 g / m². 2 above.

[0016] Furthermore, the electrochemical element of the present invention is characterized by having a positive electrode and a negative electrode, and a separator between the positive electrode and the negative electrode, wherein the separator is used as the separator of the electrochemical element of the present invention, and at least one of the positive electrode and the negative electrode is bonded to the separator through the adhesive layer of the separator.

[0017] Furthermore, the method for manufacturing an electrochemical element according to the present invention is a method for manufacturing an electrochemical element having a positive electrode and a negative electrode, and a separator between the positive electrode and the negative electrode, characterized by comprising the following steps: using the separator for electrochemical elements according to the present invention as the separator, overlapping at least one of the positive electrode and the negative electrode with the separator, and bonding the electrode to the separator by applying pressure at a temperature at which the resin (A) does not melt.

[0018] Invention Effects

[0019] According to the present invention, it is possible to provide a separator for an electrochemical element that can be bonded to an electrode without heating, an electrochemical element having the above-mentioned separator, and a method for manufacturing the same. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view schematically illustrating an example of a separator for an electrochemical element of the present invention being bonded and integrated with the positive and negative electrodes of the electrochemical element.

[0021] Figure 2 This is a top view schematically illustrating an example of the electrochemical element (non-aqueous electrolyte secondary battery) of the present invention.

[0022] Figure 3 yes Figure 2 Sectional view along line II. Detailed Implementation

[0023] <Separators for Electrochemical Components>

[0024] The separator for electrochemical devices of the present invention (hereinafter, sometimes simply referred to as "separator") has a substrate layer formed of a porous membrane and an adhesive layer for bonding to the electrodes of the electrochemical device. Furthermore, the adhesive layer contains a particulate resin (A) having a melting point of 75°C to 140°C, and the resin (A) in the adhesive layer has a unit area weight of 0.05 g / m³. 2 above.

[0025] The separator of the present invention, through the action of the adhesive layer containing resin (A) described above, can bond well to the electrode without heating (not melting) when the adhesive layer side surface overlaps with the electrode of the electrochemical element, for example, by applying pressure at room temperature. The reason for this is not yet certain, but it is speculated that when the adhesive layer is granular and contains resin (A) with the above melting point per unit area weight, the granular resin (A) is well pressed into the recessed portion of the electrode surface during pressure, thereby increasing the bonding force with the electrode through anchoring effect and the like.

[0026] Figure 1 A cross-sectional view schematically illustrating an example of the separator of the present invention is shown in the figure. Furthermore, Figure 1 The diagram illustrates the bonding of the separator to the electrodes (positive and negative electrodes) of the electrochemical element on both sides. The separator 10 has heat-resistant layers 12 on both sides of the substrate layer 11, and further, adhesive layers 13 on each of the heat-resistant layers 12. Furthermore, the lower adhesive layer 13 is bonded to the positive electrode 20, and the upper adhesive layer 13 is bonded to the negative electrode 30, thereby integrating the separator 10 with both the positive and negative electrodes 20.

[0027] also, Figure 1 In order to make it easier to understand the layer composition of the separator, the adhesive layers 13, 13 are shown in a uniform layered form, but as mentioned above, the resin (A) contained in the adhesive layers 13, 13 is in particulate form.

[0028] The resin (A) contained in the adhesive layer of the separator is a resin with a melting point of 75°C or higher and 140°C or lower. The melting point of the thermoplastic resin (A) mentioned in this specification refers to the melting temperature measured using a differential scanning calorimeter (DSC) in accordance with Japanese Industrial Standard (JIS) K 7121.

[0029] In resin (A), among resins having the above-mentioned melting point, from the perspective of having moderate deformability that makes it easy to obtain the above-mentioned bonding effect, a polymer having structural units derived from ethylene or propylene (hereinafter referred to as "PE / PP polymer") is preferred. The term "structural units derived from ethylene or propylene" here refers to structural units introduced by ethylene or propylene in a polymer obtained by polymerization of monomers containing ethylene or propylene.

[0030] As PE / PP polymers, examples include copolymers of ethylene and propylene, and copolymers of ethylene or propylene with α-olefins having 5 to 20 carbon atoms, in addition to polymers of ethylene and propylene. Examples of α-olefins with 5 to 20 carbon atoms used in copolymerization with ethylene or propylene include 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-nonadecanene, and 1-eicosene; one or more of these can be used.

[0031] The copolymer composition in copolymers of ethylene or propylene with α-olefins having 5 to 20 carbon atoms is not particularly limited as long as the melting point can be adjusted to the values ​​mentioned above. For example, in 100 moles of structural units derived entirely from monomers, the proportion of structural units derived from ethylene and propylene (the sum of both when including structural units derived from ethylene and propylene) can be set to 75 to 95 mol%, and the proportion of structural units derived from α-olefins having 5 to 20 carbon atoms can be set to 5 to 25 mol%. The term "structural units derived from α-olefins having 5 to 20 carbon atoms" refers to structural units introduced by α-olefins having 5 to 20 carbon atoms in copolymers obtained by polymerization of ethylene or monomers containing propylene and α-olefins having 5 to 20 carbon atoms.

[0032] Furthermore, as described later, the adhesive layer in the separator can be formed by coating an adhesive layer forming composition containing resin (A) dispersed in a medium such as water or an organic solvent onto a heat-resistant layer formed on the surface of a substrate layer composed of a porous membrane. In particular, to make the resin (A) an aqueous dispersion, from the viewpoint of improving its affinity with water, the PE / PP polymer can be a polymer in which structural units from polymeric monomers having polar groups are introduced into the main chain or side chain. The term "structural units from polymeric monomers having polar groups" as used here refers to structural units in which polymeric monomers having polar groups are introduced into the main chain or side chain in copolymers obtained by graft polymerization of polymeric monomers having polar groups or by polymerization of monomers containing ethylene or propylene and polymeric monomers having polar groups.

[0033] Polymerizable monomers with polar groups that can be used in copolymers with ethylene or propylene and α-olefins containing 5 to 20 carbon atoms as needed include, for example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid; derivatives of unsaturated carboxylic acids such as maleic anhydride, itaconic anhydride, and citraconic anhydride; and esters such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, monoethyl maleate, diethyl maleate, monomethyl fumarate, dimethyl fumarate, monomethyl itaconic acid, and diethyl itaconic acid.

[0034] Resin (A) may be composed of only one type of PE / PP polymer, or it may be a mixture of two or more different polymers, such as a mixture of two or more copolymers with different types of α-olefins as monomers. Alternatively, resin (A) may be a mixture of a copolymer of ethylene or propylene and a homopolymer of ethylene or propylene.

[0035] In the adhesive layer, the resin (A) is in the form of particles. As described above, by pressing the particle-shaped resin (A) into the recessed portion of the electrode surface, the adhesion between the adhesive layer and the electrode, i.e., the adhesion between the separator and the electrode, can be improved.

[0036] From the viewpoint of improving adhesion to the electrode, the average particle size of the resin (A) in the adhesive layer is preferably 3 μm or less, more preferably 2 μm or less. However, if the particle size of the resin (A) in the adhesive layer is too small, the separator may become clogged, reducing the permeability and retention of the electrolyte in the electrochemical element. Therefore, from the viewpoint of further improving the permeability and retention of the electrolyte in the separator and improving the characteristics of the electrochemical element, the average particle size of the resin (A) is preferably 0.2 μm or more, more preferably 0.3 μm or more.

[0037] The average particle size of resin (A) as described in this specification is the number-average particle size measured using a laser scattering particle size analyzer (HORIBA "LA-920"), which disperses the resin in a non-swelling medium (e.g., water).

[0038] Resin (A) can be obtained, for example, by polymerizing the aforementioned monomers using the same method employed in the polymerization of common polyolefins. Furthermore, commercially available resins (such as "CHEMIPEARL" (registered trademark) manufactured by Mitsui Chemicals Co., Ltd.) in a dispersed state in a medium such as water can also be used for resin (A). Moreover, the average particle size of the resin (A) in the adhesive layer can be adjusted, for example, by adjusting the particle size of the dispersed particles in the aqueous dispersion or organic solvent dispersion of resin (A).

[0039] From the perspective of increasing the adhesion between the separator and the electrode, the unit area weight of resin (A) in the adhesive layer is 0.05 g / m². 2 The above is preferably 0.2 g / m 2 The above, more preferably 0.3 g / m 2 That's all. Furthermore, from the viewpoint of improving the air permeability of the separator and enhancing the permeability and retention of the electrolyte in the electrochemical element, the unit area weight of the resin (A) in the adhesive layer is preferably 0.9 g / m². 2 The following, or more preferably, is 0.7 g / m 2 the following.

[0040] The adhesive layer may also contain adhesive resins other than resin (A). Examples of adhesive resins that may be contained in the adhesive layer include ethylene-vinyl acetate copolymer (EVA, a copolymer with 20 mol% to 35 mol% structural units derived from vinyl acetate), ethylene-acrylate copolymers (ethylene-ethyl acrylate copolymers, etc.), various rubbers and their derivatives [styrene-butadiene rubber (SBR), fluororubber, polyurethane rubber, ethylene-propylene-diene rubber (EPDM, etc.), cellulose derivatives [carboxymethyl cellulose (CMC), hydroxyethyl cellulose, hydroxypropyl cellulose, etc.], polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP), poly-N-vinyl acetamide (PNVA), polyurethane, epoxy resin, polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), etc., and one or more of them may be used.

[0041] When the adhesive layer contains adhesive resin, the content of adhesive resin is preferably set to 1 to 5 parts by mass relative to the content of resin (A) in the adhesive layer: 100 parts by mass.

[0042] The substrate layer of the separator is composed of a porous membrane. The porous membrane constituting the substrate layer can be a porous membrane made of thermoplastic resin, which is used as a separator in known electrochemical devices such as lithium-ion secondary batteries. More specifically, it can be an ion-permeable porous membrane (microporous membrane) produced by solvent extraction, dry or wet stretching methods, etc. Alternatively, a membrane in which inorganic fillers are retained within the pores of a thermoplastic resin nonwoven fabric can also be used as a porous membrane constituting the substrate layer.

[0043] That is, the porous membrane that forms the substrate layer is preferably composed mainly of thermoplastic resin. In this case, when the temperature inside the electrochemical element using the separator rises to above the melting point of the thermoplastic resin constituting the substrate layer of the separator, the thermoplastic resin melts and blocks the pores of the separator, causing a shutdown that inhibits the electrochemical reaction, thereby improving the safety of the electrochemical element.

[0044] The melting point of the thermoplastic resin constituting the porous membrane that forms the substrate layer varies depending on the required shut-off temperature in the electrochemical element, and is typically below 140°C. Examples of such thermoplastic resins include polyethylene (PE), polyolefins such as ethylene-propylene copolymers, etc. Therefore, a microporous membrane made of polyolefin is preferably preferred for the substrate layer.

[0045] When the porous membrane is mainly composed of a thermoplastic resin with a melting point of 140°C or less, the volume content of the thermoplastic resin, which is the main component, in the total volume of the constituent components of the porous membrane (excluding the void portion) is 50% by volume or more, more preferably 70% by volume or more. For example, when the porous membrane is formed from a microporous membrane of PE, the volume content of the thermoplastic resin (a resin with a melting point of 140°C or less) is 100% by volume.

[0046] When the porous membrane used in the substrate layer is a microporous membrane made of thermoplastic resin, the microporous membrane may contain various additives (antioxidants, etc.) and inorganic fillers (substances that are the same as the inorganic particles in the fillers that can be used in the heat-resistant layer described later).

[0047] Furthermore, when the porous membrane used in the substrate layer comprises a nonwoven fabric made of thermoplastic resin and an inorganic filler retained within its pores, the inorganic filler may be the same inorganic particles used in the filler used in the heat-resistant layer described later. Additionally, when the porous membrane used in the substrate layer comprises a nonwoven fabric made of thermoplastic resin and an inorganic filler retained within its pores, in order to ensure that the inorganic filler is well retained within the pores of the nonwoven fabric, it may further contain an adhesive resin. This adhesive resin may be the same as the adhesive resin used in the heat-resistant layer described later.

[0048] The thickness of the substrate layer (the total thickness when the separator has multiple substrate layers, as detailed later) is preferably 2 μm or more, more preferably 4 μm or more, and even more preferably 5 to 30 μm. Furthermore, the porosity of the substrate layer is preferably 35 to 80%.

[0049] The spacer may consist of only a substrate layer and an adhesive layer. In this case, the spacer may have an adhesive layer on only one side of the substrate layer or on both sides of the substrate layer, depending on the need.

[0050] In addition, the separator may have a substrate layer and an adhesive layer, as well as a heat-resistant layer to improve the shape stability of the separator when the temperature rises within the electrochemical element. By having a heat-resistant layer on the separator, for example, in the event of shutdown, it is possible to suppress the occurrence of short circuits caused by the separator shrinking and the positive and negative electrodes coming into contact, thereby further improving the safety of the electrochemical element.

[0051] The heat-resistant layer preferably contains fillers with a heat resistance temperature of 150°C or higher, thereby ensuring heat resistance. "Heat resistance temperature of 150°C or higher" as stated in this specification means that no softening or deformation is observed at at least 150°C.

[0052] The filler in the heat-resistant layer can be either inorganic or organic particles, provided it has a heat resistance temperature of 150°C or higher, is stable relative to the electrolyte of the electrochemical element, and is not easily oxidized or reduced within the operating voltage range of the electrochemical element. From a dispersion perspective, microparticles are preferred, and inorganic oxide particles are also preferred. More specifically, alumina, silica, and boehmite are preferred. Alumina, silica, and boehmite have high oxidation resistance, and their particle size and shape can be adjusted to desired values, thus facilitating precise control of the porosity of the heat-resistant layer. Furthermore, the filler with a heat resistance temperature of 150°C or higher can be used alone or in combination with two or more of the aforementioned fillers.

[0053] The amount of the filler in the heat-resistant layer is preferably 70% by volume or more, more preferably 80% by volume or more, and even more preferably 90% by volume or more in the total volume of the constituent components of the heat-resistant layer (excluding the pore portion). By making the filler in the heat-resistant layer at a high content as described above, the thermal shrinkage of the separator as a whole can be well suppressed, thus imparting high heat resistance.

[0054] Furthermore, in order to bond the fillers together or to bond the heat-resistant layer to the substrate layer, it is preferable to contain an adhesive resin in the heat-resistant layer. From this point of view, the preferred upper limit of the amount of the fillers in the heat-resistant layer is, for example, 99% by volume of the total volume of the components of the heat-resistant layer. Moreover, if the amount of the fillers in the heat-resistant layer is less than 70% by volume, it is necessary, for example, to increase the amount of adhesive resin in the heat-resistant layer. However, in this case, the voids in the heat-resistant layer are filled with the adhesive resin, and the ion permeability within the separator may be impaired.

[0055] As for the adhesive resin used in the heat-resistant layer, there are no particular limitations as long as it can effectively bond the fillers to each other, the heat-resistant layer to the substrate layer, is electrochemically stable, and is stable relative to the electrolyte of the electrochemical element. Specifically, examples include fluoropolymers (PVDF, etc.), fluororubbers, SBR, CMC, hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP), poly N-vinyl acetamide, acrylic resins (crosslinked acrylic resins, etc.), polyurethane, and epoxy resins. These adhesive resins can be used alone or in combination of two or more.

[0056] When the separator has a heat-resistant layer, the heat-resistant layer can be a single layer or two or more layers (such as having heat-resistant layers on both sides of the substrate layer). Alternatively, in this case, the substrate layer can also be a single layer or two or more layers (such as having substrate layers on both sides of the heat-resistant layer). However, if the separator has too many layers, for example, the overall thickness of the separator may become too large, making it difficult to increase the capacity of the electrochemical element. Therefore, when the separator has a heat-resistant layer, it is preferable to have one heat-resistant layer on one side of a substrate layer, or one heat-resistant layer on each side of a substrate layer.

[0057] The thickness of the heat-resistant layer (the total thickness when the separator has multiple heat-resistant layers) is preferably 1 μm or more, more preferably 2 μm or more, and preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 6 μm or less.

[0058] The total thickness of the separator is preferably 3 μm or more, more preferably 5 μm or more, even more preferably 8 μm or more, and preferably 30 μm or less, more preferably 20 μm or less.

[0059] When manufacturing the separator, for example, the following method can be used: a composition for forming an adhesive layer, comprising a resin (A) dispersed in a medium such as water or an organic solvent, is applied to the surface of a substrate layer or a heat-resistant layer formed on the substrate layer, and then dried to form an adhesive layer. Alternatively, if the adhesive layer also contains an adhesive resin, the adhesive resin can be dispersed in water or an organic solvent, which serves as the medium for forming the adhesive layer composition, or it can be dissolved in these media.

[0060] In addition, when manufacturing a separator with a heat-resistant layer, the heat-resistant layer can be formed, for example, by coating a heat-resistant layer forming composition (slurry, paste, etc.) containing the aforementioned filler, binder resin, and solvent (water, ketones, organic solvents, etc.) onto a substrate layer and then drying it.

[0061] The adhesive layer can be formed on the substrate layer. Alternatively, in the case of a separator with a heat-resistant layer, it can also be formed on the heat-resistant layer. However, the adhesion between the adhesive layer and the heat-resistant layer is more likely to be greater than the adhesion between the adhesive layer and the substrate layer. Therefore, it is more preferable for the separator to have a heat-resistant layer on one or both sides of the substrate layer and an adhesive layer on the heat-resistant layer. In this case, the adhesion (peel strength) to the electrode of the electrochemical element can be further improved.

[0062] Furthermore, from the viewpoint of ensuring good permeability of the liquid electrolyte (electrolyte) in the electrochemical element and improving the characteristics of the electrochemical element, the air permeability of the separator is preferably 400 sec / 100 mL or less, more preferably 300 sec / 100 mL or less. Additionally, from the viewpoint of increasing the strength of the separator to a certain extent, the air permeability of the separator is preferably 50 sec / 100 mL or more, more preferably 70 sec / 100 mL or more, and even more preferably 100 sec / 100 mL or more.

[0063] The air permeability of the separators mentioned in this specification is determined by the Gli method as specified in JIS P 8117.

[0064] <Electrochemical Components>

[0065] The electrochemical element of the present invention has a positive electrode and a negative electrode, and a separator between the positive electrode and the negative electrode. The separator is used as the separator, and at least one of the positive and negative electrodes is bonded to the separator via an adhesive layer provided with the separator. That is, there are no particular limitations on the configuration and structure of the electrochemical element other than those described above, and various configurations and structures used in known electrochemical elements such as lithium-ion secondary batteries can be applied.

[0066] The electrochemical elements of the present invention include: various primary and secondary batteries (alkaline primary batteries, alkaline secondary batteries, manganese batteries, etc.) having an aqueous electrolyte (electrolyte, etc.); various primary and secondary batteries (non-aqueous electrolyte primary batteries such as lithium primary batteries, non-aqueous electrolyte secondary batteries such as lithium-ion secondary batteries); and supercapacitors having a non-aqueous electrolyte, etc.

[0067] In the electrochemical element of the present invention, at least one of the positive and negative electrodes is bonded to the separator via an adhesive layer provided by the separator. Therefore, even if volume changes occur in the electrodes during use of the electrochemical element, changes in the spacing or local variations between the positive and negative electrodes can be suppressed, thus maintaining the characteristics of the electrochemical element well. Furthermore, in the present invention, either the positive or negative electrode can be bonded to the separator, but from the viewpoint of better maintaining the characteristics of the electrochemical element, it is preferable that both the positive and negative electrodes are bonded to the separator.

[0068] The following description uses a non-aqueous electrolyte secondary battery, which is a representative electrochemical element of the present invention, as an example.

[0069] As a positive electrode for a non-aqueous electrolyte secondary battery, a positive electrode with a structure having a positive electrode composite layer containing lithium-containing transition metal oxides, binders, and conductive additives as positive electrode active materials on one or both sides of the current collector can be used.

[0070] As a specific example of a positive electrode active material, namely a lithium-containing transition metal oxide, LiM can be cited as an example. x Mn 2-x O4 (where M is at least one element selected from the group consisting of Li, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Fe, Co, Ni, Cu, Al, Sn, Sb, In, Nb, Mo, W, Y, Ru, and Rh, 0.01≤x≤0.5) represents spinel-type lithium manganese composite oxide, Li x Mn （1-y-x） Ni y M z O （2-k） F l (Where M is at least one element selected from the group consisting of Co, Mg, Al, B, Ti, V, Cr, Fe, Cu, Zn, Zr, Mo, Sn, Ca, Sr, and W, and 0.8≤x≤1.2, 0<y<0.5, 0≤z≤0.5, k+l<1, -0.1≤k≤0.2, 0≤l≤0.1) represents a layered compound, LiCo 1-x M xO2 (where M is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Fe, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, 0≤x≤0.5) represents lithium cobalt composite oxides, LiNi 1-x M x O2 (where M is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Fe, Co, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, 0 ≤ x ≤ 0.5) represents lithium-nickel composite oxides, LiM 1-x N x O2 (where M is at least one element selected from the group consisting of Fe, Mn and Co, and N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb and Ba, 0≤x≤0.5) represents olivine-type composite oxides, etc., and only one of them may be used, or two or more may be used together.

[0071] As a binder for the positive electrode, fluoropolymers such as PVDF are used. In addition, as a conductive additive for the positive electrode, carbon materials such as carbon black are used.

[0072] The positive electrode can be manufactured, for example, by dispersing a positive electrode mixture containing a positive electrode active material, a conductive additive, and a binder in a solvent such as N-methyl-2-pyrrolidone (NMP) to prepare a composition (slurry, paste, etc.) containing a positive electrode mixture, coating it onto a current collector and drying it, and then subjecting it to pressing treatments such as calendering as needed. However, the manufacturing method of the positive electrode is not limited to the above method, and other methods can also be used.

[0073] In addition, as the current collector of the positive electrode, aluminum foil, perforated metal, mesh, expanded metal, etc. can be used, and aluminum foil with a thickness of 10 to 30 μm is usually preferred.

[0074] The lead portion on the positive electrode side is typically configured as follows: during the fabrication of the positive electrode, a portion of the current collector that remains exposed without forming a positive electrode flux layer is used as the lead portion. However, the lead portion does not necessarily need to be integrated with the current collector from the beginning; it can also be configured by subsequently connecting an aluminum foil or similar material to the current collector.

[0075] As the negative electrode for a non-aqueous electrolyte secondary battery, there are no particular restrictions as long as it is a negative electrode used in known lithium-ion secondary batteries, i.e., a negative electrode containing an active material capable of absorbing and releasing Li ions. For example, as the active material, one or more of the following carbon materials capable of absorbing and releasing lithium can be used: graphite, pyrolytic carbon, coke, glassy carbon, sintered organic polymers, mesophase carbon microspheres (MCMB), carbon fibers, etc. Alternatively, compounds containing elements such as Si, Sn, Ge, Bi, Sb, In, their compounds and alloys, lithium-containing nitrides, or oxides that can be charged and discharged at low voltages close to that of lithium metal, or lithium metal, lithium / aluminum alloys, and materials composed of Li4Ti5O4 can also be used. 12 Ti oxide is used as the negative electrode active material. For negative electrode additives made by appropriately adding conductive additives (carbon materials such as carbon black), binders such as PVDF, etc. to these negative electrode active materials, for example, negative electrode additives can be obtained by finely machining a current collector as the core material into a molded body (negative electrode additive layer) using the same method as the method described above for forming the positive electrode additive layer, or negative electrode additives can be obtained by laminating the above-mentioned various alloys and lithium metal foils alone or as negative electrode additive layers onto the current collector.

[0076] When a current collector is used at the negative electrode, it can be made of copper or nickel foil, perforated metal, mesh, expanded metal, etc., with copper foil being the most common. To obtain a high-energy-density electrochemical element, the overall thickness of the negative electrode current collector should be thinned, with an upper limit of 30 μm and a lower limit of 5 μm. Furthermore, the lead portion on the negative electrode side can be formed in the same manner as the lead portion on the positive electrode side.

[0077] The aforementioned positive and negative electrodes can be stacked with the separator of the present invention in between, to form a stacked electrode body formed by bonding at least one of the positive and negative electrodes to the separator, or to form a wound electrode body formed by further winding it. Furthermore, after forming the wound electrode body, pressure can be applied to bond the electrode to the separator.

[0078] Non-aqueous electrolyte secondary batteries can use solutions (non-aqueous electrolytes) made by dissolving lithium salts in organic solvents. As for lithium salts, any solution that dissociates in a solvent to form Li2... + There are no particular restrictions on lithium salts whose ions are unlikely to cause decomposition or other side reactions within the voltage range used as electrochemical elements. For example, inorganic lithium salts such as LiClO4, LiPF6, LiBF4, LiAsF6, and LiSbF6 can be used; LiCF3SO3, LiCF3CO2, Li2C2F4(SO3)2, LiN(CF3SO2)2, LiC(CF3SO2)3, and LiC... n F 2n+1SO3 (n≥2), LiN (R) f OSO2)2 [here R] f Organolithium salts such as fluoroalkyl groups.

[0079] As for organic solvents used in non-aqueous electrolytes, there are no particular limitations as long as they can dissolve the aforementioned lithium salts and do not undergo decomposition or other side reactions within the voltage range used as electrochemical elements. Examples include cyclic carbonates such as ethylene carbonate, propylene carbonate, butyl 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 dimethoxyethane, diethyl ether, 1,3-dioxolane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether; cyclic ethers such as dioxane, tetrahydrofuran, and 2-methyltetrahydrofuran; nitrile compounds such as acetonitrile, propionitrile, and methoxypropionitrile; and sulfite compounds such as ethylene glycol sulfite. Two or more of these can also be used in combination.

[0080] The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.5 to 1.5 mol / L, more preferably 0.9 to 1.25 mol / L.

[0081] Alternatively, gel-like non-aqueous electrolytes (gel electrolytes) can be prepared by adding known polymers or other gelling agents.

[0082] Examples of electrochemical elements of the present invention, primarily non-aqueous electrolyte secondary batteries, include cylindrical shapes (square, cylindrical, etc.) using steel or aluminum cans as outer packaging. Alternatively, flexible encapsulated elements can be manufactured using a laminated film coated with vapor-deposited metal as the outer packaging.

[0083] Furthermore, when the positive and negative electrodes are composed of an additive layer containing active materials (positive electrode additive layer and negative electrode additive layer), the adhesion to the separator can be further increased. This is presumably because, since the additive layers of the positive and negative electrodes are porous, the particulate resin (A) contained in the adhesive layer of the separator is pressed into the pores and other recessed areas on its surface, thus exerting an excellent anchoring effect.

[0084] The electrochemical element of the present invention can be manufactured, for example, by a method comprising a step of forming an electrode body (a stacked electrode body, a wound electrode body, etc.) by stacking a positive electrode, a negative electrode, and a separator, and a step of encapsulating the electrode body obtained by this step together with an electrolyte into an outer casing. Furthermore, in the step of forming the electrode body, at least one of the positive and negative electrodes is overlapped with a separator, and an adhesive layer of the separator is bonded to the electrode. During this bonding, pressure is applied at a temperature at which the resin (A) contained in the adhesive layer does not melt. That is, the pressure applied for bonding the adhesive layer of the separator to the electrode can be performed without heating, for example at room temperature; however, as long as the temperature at which the resin (A) does not melt, pressure can be applied while heating, for example, by heating to below 70°C.

[0085] If the separator is the one of the present invention, as described above, the adhesion to the electrode can be increased by applying pressure without heating. For example, the peel strength between the separator and the electrode can be made to be 0.4 N / m or more, preferably 1.0 N / m or more. There is no particular limit to the upper limit of the peel strength between the separator and the electrode, which is usually around 5.0 N / m.

[0086] The peel strength between the separator and the electrode, as described in this specification, is measured using the following method. A test piece is cut with a length of 110 mm in the MD direction and a width of 20 mm in the TD direction. The adhesive layer of the test piece and the adhesive layer of an electrode sheet cut to 110 mm × 25 mm are placed face-to-face and overlapped, and the test piece is placed in a manual press with the pre-temperature adjusted to a predetermined temperature. The overlap length between the test piece and the electrode is 10 cm. The test piece is held under a predetermined load for a predetermined time to bond it to the electrode, thus creating a sample for peel strength measurement. Next, using double-sided adhesive tape (manufactured by Nitto Denko Co., Ltd., N5605), the electrode side of the sample is adhered to a stainless steel plate (SUS plate). Furthermore, to facilitate installation on the tensile testing machine, after applying tape in a U-shape to one end of the test piece (separator) that does not overlap with the electrode, the SUS plate was placed on the tensile testing machine (Minebea: TGE-10kN). The tape portion was stretched for 24 seconds at a tensile direction of 90° and a tensile speed of 200 mm / min, and the adhesion force to the electrode was measured (the average peel force in the peel force curve obtained through testing). Each specimen was measured three times, and the average of their adhesion forces was taken as the peel strength between the separator and the electrode.

[0087] In addition, the temperature, load, and holding time when the test piece is bonded to the electrode can be set to the conditions in the actual manufacturing process of the electrochemical device.

[0088] Example

[0089] The present invention will now be described in detail based on embodiments. However, the following embodiments do not limit the present invention.

[0090] Example 1

[0091] <Making of the separator>

[0092] 5 kg of powder containing plate-shaped boehmite (average primary particle size 1 μm, aspect ratio 10) was mixed with 5 kg of ion-exchanged water and 0.5 kg of dispersant (aqueous polycarboxylate ammonium salt, solids concentration 40% by mass). The mixture was then subjected to a ball mill with an internal volume of 20 L and a rotation speed of 40 rpm for 10 hours to prepare a dispersion. A portion of the treated dispersion was vacuum-dried at 120 °C and observed using a scanning electron microscope (SEM). The results showed that the boehmite was approximately plate-shaped. Furthermore, the average particle size of the treated boehmite was 1 μm, confirming that the crushing was thorough.

[0093] Add 0.5g of xanthan gum as a thickener and 17g of resin binder dispersion (containing modified polybutyl acrylate and PNVA at a mass ratio of 2:1, with a solid content of 45% by mass) to 500g of the above dispersion. Stir for 3 hours using a "Three-one motor" (product name) manufactured by Shin-Tung Science Co., Ltd. to prepare a uniform heat-resistant layer forming slurry (solid content ratio of 50% by mass).

[0094] A polyolefin microporous laminate (total thickness 12 μm, porosity 50%) was used as the substrate layer, consisting of a 4 μm thick polyethylene intermediate layer and an outer 4 μm thick polypropylene layer stacked on both sides. Both sides of the substrate layer were subjected to corona discharge treatment (discharge rate 40 W·min / m). 2 A heat-resistant layer forming slurry is applied to the treated surface using a micro-gravure coating machine and then dried to form a heat-resistant layer on both sides of the substrate layer. The thickness of the heat-resistant layer on both sides is 1.9 μm.

[0095] Next, as a composition for forming an adhesive layer containing resin (A), an aqueous dispersion of a propylene polymer [Mitsui Chemicals Co., Ltd. "CHEMIPEARL (registered trademark) EP151H", melting point of resin (A) 80°C, average particle size of resin (A) 0.4 μm] was applied to one side of the heat-resistant layer formed on both sides of the substrate layer, such that the dried resin (A) has a unit area weight of 0.4 g / m². 2 The material is dried to obtain a separator with an adhesive layer composed of granular resin (A) on one side.

[0096] <Measurement of air permeability (initial test)>

[0097] The prepared separator was cut into 5cm × 5cm pieces, and its air permeability was measured using the Wang Yan-style testing machine method described in JIS P8117:2009. The average air permeability of the separator cut at three locations was taken as the initial air permeability of the separator. The measured initial air permeability was 205 seconds / 100mL.

[0098] <The Making of the Positive Electrode>

[0099] LiMn will be used as the positive electrode active material 1.5 Ni 0.5 O4: 85 parts by weight, acetylene black as a conductive additive: 10 parts by weight, and PVDF as a binder: 5 parts by weight are mixed evenly with NMP as a solvent to prepare a paste containing a positive electrode additive. This paste is intermittently coated onto both sides of an aluminum foil with a thickness of 15 μm, which serves as a current collector. After drying, it is calendered to adjust the thickness of the positive electrode additive layer to a total thickness of 150 μm. The foil is then cut into a shape with a width of 105 mm, a length of 200 mm, and an exposed portion containing the positive electrode current collector. A tab is then welded to the exposed portion of the aluminum foil to form a lead portion, thus producing the positive electrode. Furthermore, in the subsequent measurements of air permeability (after bonding) and peel strength, the produced positive electrode is cut to a predetermined size for use.

[0100] <Making the Negative Electrode>

[0101] 95 parts by mass of graphite (as the negative electrode active material) and 5 parts by mass of PVDF (as the binder) were mixed evenly with NMP as a solvent to prepare a paste containing the negative electrode additive. This paste containing the negative electrode additive was intermittently coated onto both sides of a 10 μm thick current collector formed from copper foil. After drying, it was calendered to adjust the thickness of the negative electrode additive layer to a total thickness of 142 μm. The layer was then cut into a shape with a width of 110 mm, a length of 205 mm, and an exposed portion of the negative electrode current collector. A tab was then welded to the exposed portion of the copper foil to form a lead portion, thus fabricating the negative electrode. Furthermore, in the peel strength measurement described later, the fabricated negative electrode was cut to a predetermined size for use.

[0102] <Measurement of air permeability (after bonding)>

[0103] The prepared separator was cut into 50mm x 50mm pieces. With PTFE sheets, each 50μm thicker than the separator, placed on both sides, the adhesive layer of the separator was placed on a 50mm x 50mm positive electrode, facing towards the positive electrode. The entire assembly was pressed down with a load of 3.9MPa for 10 seconds, thereby flattening the adhesive layer. This state of the adhesive layer was considered bonded to the positive electrode. The separator was then peeled off from the PTFE sheets, and the air permeability of the separator cut at three points was measured in the same manner as before. The average value was taken as the air permeability of the separator after bonding. The measured air permeability after bonding was 220 seconds / 100mL.

[0104] <Measurement of peel strength>

[0105] (Measurement 1-1)

[0106] The separator was cut with a length of 110 mm in the MD direction and a width of 20 mm in the TD direction. Then, the positive electrode was cut into 110 mm × 25 mm pieces, and a sample for peel strength measurement was prepared using the above method. Furthermore, the temperature of the manual press used for bonding was 25°C, the load was 3.9 MPa, and the holding time was 10 seconds to bond the positive electrode and the separator.

[0107] Using the prepared peel strength test specimen, the peel strength between the positive electrode and the separator was measured by the above method, and the result was 1.3 N / m.

[0108] (Measurement 1-2)

[0109] Except for the load of 6.4 MPa and the holding time of 60 seconds when bonding the positive electrode and the separator, the sample for peel strength measurement was prepared in the same manner as in Measurement 1-1, and the peel strength between the positive electrode and the separator was measured, with a result of 4.2 N / m.

[0110] (Measurements 1-3)

[0111] Except for the load of 17.7 MPa when bonding the positive electrode and the separator, the same specimen for peel strength measurement was prepared as in Measurement 1-1, and the peel strength between the positive electrode and the separator was measured, with a result of 7.6 N / m.

[0112] (Measurements 1-4)

[0113] Instead of the positive electrode, the negative electrode was cut into 110mm × 25mm pieces. During bonding, the temperature of the manual press was 25°C, the load was 3.9 MPa, and the holding time was 10 seconds to bond the negative electrode to the separator. Otherwise, a sample for peel strength measurement was prepared in the same manner as in measurement 1-1. Using the prepared sample for peel strength measurement, the peel strength between the negative electrode and the separator was measured using the above method, and the result was 0.9 N / m.

[0114] (Measurements 1-5)

[0115] Except for the load of 6.4 MPa and the holding time of 60 seconds when bonding the negative electrode to the separator, the sample for peel strength measurement was prepared in the same manner as for measurements 1-4, and the peel strength between the negative electrode and the separator was measured, with a result of 3.7 N / m.

[0116] (Measurements 1-6)

[0117] Except for the temperature of 70°C and the load of 2.5MPa when bonding the positive electrode and the separator, the sample for peel strength measurement was prepared in the same manner as in Measurement 1-1. The peel strength between the positive electrode and the separator was measured, and the result was 6.6N / m.

[0118] (Measurements 1-7)

[0119] Except for the temperature of 70°C and the load of 2.5MPa when bonding the negative electrode and the separator, the sample for peel strength measurement was prepared in the same manner as for measurements 1-4. The peel strength between the negative electrode and the separator was measured, and the result was 7.4N / m.

[0120] Example 2

[0121] The dried resin (A) has a unit area weight of 0.2 g / m². 2 and 0.6g / m 2 The adhesive layer forming composition used in Example 1 was applied in the same manner as in Example 1, except that two separators with adhesive layers having different weights per unit area were obtained.

[0122] <Measurement of peel strength>

[0123] (Measurement 2-1)

[0124] The weight per unit area of ​​the dried resin (A) is 0.2 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 4.5 N / m.

[0125] (Measurement 2-2)

[0126] The weight per unit area of ​​the dried resin (A) is 0.6 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 9.2 N / m.

[0127] Example 3

[0128] As a composition for forming an adhesive layer containing resin (A), 100 parts by weight of the above polymer relative to the aqueous dispersion of the propylene polymer used in Example 1 are used, and a composition of the resin adhesive dispersion also used in Example 1 is added in a ratio of 6.7 parts by weight (containing 2 parts by weight of modified polybutyl acrylate and 1 part by weight of PNVA). Otherwise, the operation is the same as in Example 1 to obtain a separator having an adhesive layer formed of particulate resin (A) on one side.

[0129] <Measurement of peel strength>

[0130] (Measurement 3-1)

[0131] For the obtained separator, the peel strength between the positive electrode and the above separator was measured in the same manner as measurements 1-2 in Example 1, and the result was 6.0 N / m.

[0132] In addition, the air permeability of the above-mentioned separator was measured. The initial air permeability was 210 seconds / 100mL, and the air permeability after bonding with the positive electrode was 220 seconds / 100mL.

[0133] (Measurement 3-2)

[0134] For the obtained separator, the peel strength between the negative electrode and the above separator was measured in the same manner as measurements 1-5 in Example 1, and the result was 5.8 N / m.

[0135] Example 4

[0136] As a composition for forming an adhesive layer containing resin (A), an aqueous dispersion of an ethylene polymer [Mitsui Chemicals Co., Ltd. "CHEMIPEARL (registered trademark) W700", melting point of resin (A) 127°C, average particle size of resin (A) 1 μm] was used. Otherwise, a separator having an adhesive layer formed of particulate resin (A) on one side was obtained in the same manner as in Example 1.

[0137] <Measurement of peel strength>

[0138] (Measurement 4-1)

[0139] For the obtained separator, the peel strength between the positive electrode and the above separator was measured in the same manner as measurement 1-1 in Example 1, and the result was 0.6 N / m.

[0140] (Measurement 4-2)

[0141] For the obtained separator, the load for bonding the positive electrode to the separator was set to 6.4 MPa, and the holding time was set to 60 seconds. Otherwise, the same sample for peel strength measurement was prepared as in measurement 4-1, and the peel strength between the positive electrode and the separator was measured. The result was 1.5 N / m.

[0142] (Measurement 4-3)

[0143] For the obtained separator, the load for bonding the positive electrode to the separator was set to 17.7 MPa. Otherwise, the same sample for peel strength measurement was prepared as in measurement 4-1, and the peel strength between the positive electrode and the separator was measured. The result was 2.5 N / m.

[0144] Example 5

[0145] The weight per unit area of ​​the dried resin (A) is 0.2 g / m². 2 The adhesive layer forming composition used in Example 4 is applied in the same manner as in Example 1, except that a separator having an adhesive layer composed of particulate resin (A) on one side is obtained.

[0146] <Measurement of peel strength>

[0147] (Measurement 5-1)

[0148] For the obtained separator, the peel strength between the positive electrode and the above separator was measured in the same manner as measurement 4-3 in Example 4, and the result was 1.2 N / m.

[0149] Example 6

[0150] As a composition for forming an adhesive layer containing resin (A), an aqueous dispersion of an ethylene-based polymer [Mitsui Chemicals Co., Ltd. "CHEMIPEARL (registered trademark) W401", melting point of resin (A) 109°C, average particle size of resin (A) 1 μm] is applied to one side of a heat-resistant layer formed on both sides of a substrate layer, such that the dried area weight of resin (A) is 0.2 g / m². 2 and 0.4g / m 2 In addition, two types of separators with different adhesive layers per unit area weight were obtained in the same manner as in Example 1.

[0151] <Measurement of peel strength>

[0152] (Measurement 6-1)

[0153] The weight per unit area of ​​the dried resin (A) is 0.2 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 2.7 N / m.

[0154] (Measurement 6-2)

[0155] The weight per unit area of ​​the dried resin (A) is 0.4 g / m². 2The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 5.7 N / m.

[0156] Example 7

[0157] As a composition for forming an adhesive layer containing resin (A), an aqueous dispersion of an ethylene-based polymer [Mitsui Chemicals Co., Ltd. "CHEMIPEARL (registered trademark) W4005", melting point of resin (A) 108°C, average particle size of resin (A) 0.6 μm] is applied to one side of a heat-resistant layer formed on both sides of a substrate layer, such that the dried area weight of resin (A) is 0.05 g / m². 2 and 0.4g / m 2 In addition, two types of separators with different adhesive layers per unit area weight were obtained in the same manner as in Example 1.

[0158] <Measurement of peel strength>

[0159] (Measurement 7-1)

[0160] The unit area weight of the dried resin (A) is 0.05 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 2.3 N / m.

[0161] (Measurement 7-2)

[0162] The weight per unit area of ​​the dried resin (A) is 0.4 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 6.6 N / m.

[0163] Example 8

[0164] As a composition for forming an adhesive layer containing resin (A), an aqueous dispersion of an ethylene-based polymer [Mitsui Chemicals Co., Ltd. "CHEMIPEARL (registered trademark) W900", resin (A) melting point 125°C, resin (A) average particle size 0.6 μm] is applied to one side of a heat-resistant layer formed on both sides of a substrate layer, such that the dried area weight of resin (A) is 0.05 g / m². 2 0.2g / m 2 and 0.4g / m 2 In addition, three types of separators with different adhesive layers per unit area weight were obtained in the same manner as in Example 1.

[0165] <Measurement of peel strength>

[0166] (Measurement 8-1)

[0167] The unit area weight of the dried resin (A) is 0.05 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 1.3 N / m.

[0168] (Measurement 8-2)

[0169] The weight per unit area of ​​the dried resin (A) is 0.2 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 2.0 N / m.

[0170] (Measurement 8-3)

[0171] The weight per unit area of ​​the dried resin (A) is 0.4 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 7.1 N / m.

[0172] Example 9

[0173] As a composition for forming an adhesive layer containing resin (A), an aqueous dispersion of an ethylene-based polymer [GifuShellat Manufacturing Co., Ltd. "AB-50", resin (A) melting point 125°C, resin (A) average particle size 1 μm] is applied to one side of a heat-resistant layer formed on both sides of a substrate layer, such that the dried resin (A) has a unit area weight of 0.05 g / m². 2 0.1g / m 2 and 0.2g / m 2 In addition, three types of separators with different adhesive layers per unit area weight were obtained in the same manner as in Example 1.

[0174] <Measurement of peel strength>

[0175] (Measurement 9-1)

[0176] The unit area weight of the dried resin (A) is 0.05 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 0.6 N / m.

[0177] (Measurement 9-2)

[0178] The weight per unit area of ​​the dried resin (A) is 0.1 g / m². 2 The separation strength between the positive electrode and the separation element was measured in the same manner as measurements 1-3 in Example 1, and the result was 0.9 N / m.

[0179] (Measurement 9-3)

[0180] The weight per unit area of ​​the dried resin (A) is 0.2 g / m². 2 The separator was measured in the same manner as measurements 1-3 in Example 1, and the peel strength between the positive electrode and the separator was measured, with a result of 2.5 N / m.

[0181] Comparative Example 1

[0182] A separator with heat-resistant layers formed on both sides of a substrate layer but without an adhesive layer on the surface was directly used. Similar to measurement 1-1 in Example 1, it was overlapped with the positive electrode to bond them together, but no bond was formed, and the peel strength was 0 N / m. Similarly, when bonded to the negative electrode in the same manner as measurement 1-4 in Example 1, the peel strength was also 0 N / m, the same as with the positive electrode.

[0183] In addition, the initial permeability of the separator in Comparative Example 1 was 185 seconds / 100 mL, and the permeability after being compressed together with the PTFE sheet and the positive electrode, as measured in the same manner as in Example 1, was 190 seconds / 100 mL.

[0184] Comparative Example 2

[0185] As a composition for forming an adhesive layer, an aqueous dispersion of PVDF particles with an average particle size of 0.4 μm is used. Otherwise, a separator having an adhesive layer composed of PVDF particles on one side is obtained in the same manner as in Example 1.

[0186] <Measurement of peel strength>

[0187] (Measurement 2C-1)

[0188] For the obtained separator, the peel strength between the positive electrode and the above separator was measured in the same manner as measurement 1-1 in Example 1, and the result was 0.2 N / m.

[0189] (Measurement 2C-2)

[0190] For the obtained separator, the peel strength between the negative electrode and the above separator was measured in the same manner as measurements 1-4 in Example 1, and the result was approximately 0 N / m.

[0191] Table 1 shows the composition of the adhesive layer [resin (A)] of the separators in Examples 1 to 9 and Comparative Examples 1 and 2. Table 2 shows the preparation conditions (pressing conditions) of the test specimens for measuring the peel strength between the electrode (positive electrode or negative electrode) and the separator, as well as the measurement results of the peel strength.

[0192] [Table 1]

[0193]

[0194] [Table 2]

[0195]

[0196] Example 10

[0197] <Making of the separator>

[0198] Similar to Example 1, the heat-resistant layers formed on both sides of the substrate layer were each 0.4 g / m² of the dried resin (A). 2 The resin was coated and dried to obtain a separator with an adhesive layer containing granular resin (A) on both sides. The separator was then cut into 115mm × 220mm pieces for battery assembly.

[0199] <Battery Assembly>

[0200] The positive and negative electrodes prepared in Example 1 are overlapped with the above-mentioned separator with the positive and negative electrode mixture layers facing the separator side respectively. The positive and negative electrodes are bonded to the separator by applying a pressure of 3.9 MPa for 10 seconds at 25°C to obtain a laminated electrode body.

[0201] Two rectangular metal laminates (rectangular, 130mm × 240mm) with a thickness of 150μm, consisting of a polyester film, an aluminum film, and a modified polyolefin film, were used as the outer casing. The aforementioned laminated electrode and a solution containing LiPF6 dissolved in a solvent of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 1:2 (1:2 volume ratio) were then encapsulated within the outer casing, thereby obtaining… Figure 2 The appearance shown Figure 3 The structure shown is a non-aqueous electrolyte secondary battery.

[0202] Here, on Figure 2 as well as Figure 3 To explain, Figure 2 This is a schematic top view representing a non-aqueous electrolyte secondary battery. Figure 3 yes Figure 2 A cross-sectional view along line II. The non-aqueous electrolyte secondary battery 100 is housed within a laminated membrane casing 400 composed of two metal laminated films, forming a laminated electrode body 500 and an electrolyte (non-aqueous electrolyte, not shown). The laminated membrane casing 400 is sealed at its outer periphery by thermally fusing the upper and lower laminated films. Furthermore, in... Figure 3 In order to avoid complicating the accompanying drawings, the layers constituting the laminated film outer casing 400, as well as the positive electrodes, negative electrodes, and spacers constituting the laminated electrode body 500, are not shown separately.

[0203] The positive electrode constituting the laminated electrode body 500 is connected to the positive external terminal 200 within the battery 100 via a tab. Similarly, although not shown, the negative electrode constituting the laminated electrode body 500 is also connected to the negative external terminal 300 within the battery 100 via a tab. Furthermore, one end of both the positive external terminal 200 and the negative external terminal 300 is extended to the outside of the laminated film outer casing 400 to facilitate connection to external devices, etc.

[0204] Comparative Example 3

[0205] Except for using the same separator as in Comparative Example 1, a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 10.

[0206] The non-aqueous electrolyte secondary batteries of Example 10 and Comparative Example 3 were charged to 4.2V with a constant current of 600mA, and then charged to 10mA with a constant voltage of 4.2V. They were then discharged to 2.5V with a current of 600mA, and the discharge capacity (standard capacity) was measured.

[0207] Next, after charging under the above conditions, the capacitor was discharged to 2.5V at a current of 3A, and the discharge capacity (high current capacity) was measured. The ratio of the high current capacity to the standard capacity was then used as the load characteristic. The results are shown in Table 3.

[0208] [Table 3]

[0209]

[0210] The non-aqueous electrolyte secondary battery of Example 10, which uses the separator of the present invention with an adhesive layer, has load characteristics that are substantially the same as those of the non-aqueous electrolyte secondary battery of Comparative Example 3, which uses a conventional separator without an adhesive layer. These results demonstrate that, in the separator of the present invention with an adhesive layer, the reduction in load characteristics caused by the adhesive layer is minimal, and a non-aqueous electrolyte secondary battery with excellent characteristics can be constructed.

[0211] This invention can also be implemented in ways other than those described above without departing from its spirit. The embodiments disclosed in this application are examples, and the invention is not limited to these embodiments. The scope of the invention is interpreted preferentially to the description of the appended technical solutions compared to the description above, and all modifications within the scope equivalent to the scope of the technical solutions are included in the scope of the technical solutions.

[0212] Industrial utilization potential

[0213] The electrochemical element of the present invention can be applied to various applications similar to those using known electrochemical elements such as lithium-ion secondary batteries. Furthermore, the separator used in the electrochemical element of the present invention can be used to construct the electrochemical element of the present invention.

[0214] By applying the separator of the electrochemical element of the present invention to the electrochemical element, it is possible to help achieve the goals of the United Nations Sustainable Development Goals (SDGs) 17, including Goal 3 (ensuring healthy lives and promoting well-being for all people of all ages), Goal 7 (ensuring access to affordable and reliable sustainable modern energy for all people), Goal 11 (enabling sustainable cities and human habitation in an inclusive, safe and resilient (regulated environment) manner), and Goal 12 (ensuring sustainable production and consumption patterns).

[0215] Symbol Explanation

[0216] 10—Separator for electrochemical element; 11—Substrate layer; 12—Heat-resistant layer; 13—Adhesive layer; 20—Positive electrode; 30—Negative electrode; 100—Non-aqueous electrolyte secondary battery (electrochemical element); 200—Positive electrode external terminal; 300—Negative electrode external terminal; 400—Laminated film outer casing; 500—Laminated electrode body.

Claims

1. A separator for an electrochemical element, comprising: a substrate layer formed of a porous membrane; and an adhesive layer for bonding to the electrodes of the electrochemical element, characterized in that, The adhesive layer contains particulate resin (A). The melting point of the resin (A) is 75℃~140℃. The resin (A) in the adhesive layer has a unit area weight of 0.05 g / m². 2 above.

2. The separator for electrochemical elements according to claim 1, characterized in that, The resin (A) in the adhesive layer has a unit area weight of 0.2 g / m². 2 above.

3. The separator for electrochemical elements according to claim 1, characterized in that, The resin (A) in the adhesive layer has a unit area weight of 0.9 g / m². 2 the following.

4. The separator for electrochemical elements according to claim 1, characterized in that, The average particle size of the resin (A) is 0.2–3 μm.

5. The separator for electrochemical elements according to claim 1, characterized in that, The air permeability is 50–400 sec / 100 mL.

6. The separator for an electrochemical element according to claim 1, characterized in that, The resin (A) contains a polymer having structural units derived from ethylene or propylene.

7. The separator for an electrochemical element according to claim 6, characterized in that, The adhesive layer contains an adhesive resin that is different from the resin (A).

8. The separator for an electrochemical element according to claim 1, characterized in that, The substrate layer has a heat-resistant layer containing fillers with a heat resistance temperature of 150°C or higher on one or both sides.

9. The separator for an electrochemical element according to claim 8, characterized in that, The heat-resistant layer has the adhesive layer.

10. The separator for an electrochemical element according to claim 1, characterized in that, The substrate layer has a microporous membrane made of polyolefin.

11. An electrochemical element having a positive electrode and a negative electrode, and a separator between the positive electrode and the negative electrode, characterized in that, The separator for the electrochemical element as described in any one of claims 1 to 10 is used as the separator. At least one of the positive and negative electrodes is bonded to the separator via the adhesive layer of the separator.

12. The electrochemical element according to claim 11, characterized in that, The peel strength between the electrode and the separator bonded by the adhesive layer is 0.4 N / m or higher.

13. The electrochemical element according to claim 11, characterized in that, The electrode, which is bonded to the separator via the adhesive layer, has an agent layer containing active material.

14. A method for manufacturing an electrochemical element, comprising manufacturing an electrochemical element having a positive electrode and a negative electrode, and a separator between the positive electrode and the negative electrode, characterized in that, The separator for the electrochemical element according to any one of claims 1 to 10 is used as the separator. The process includes: overlapping at least one of the positive and negative electrodes with the separator, and applying pressure at a temperature at which the resin (A) does not melt, thereby bonding the electrodes to the separator.

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