Battery packaging material

Abstract

By using a specific lubricant in the heat-fusible resin layer of the battery packaging material, slidability during molding is improved, and deterioration of battery performance is suppressed. A battery packaging material (1) comprising at least a base material layer (13), a barrier layer (11), and a heat-fusible resin layer (15) in this order from the outside to the inside, the heat-fusible resin layer (15) comprising a polyolefin resin and one or more types of lubricant, and at least one type of lubricant being an N-substituted amide represented by formula (I). R1 is a hydrocarbon chain represented by Cm1Hn1; and R2 represents a hydrocarbon chain represented by Cm < 2 > Hn < 2 >. [Chemical Formula 4] # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a battery packaging material that can be suitably used as a case for secondary batteries such as in-vehicle use, stationary use, laptop use, mobile phone use, and camera use, particularly a small portable lithium-ion secondary battery. Background Art

[0002] Regarding power storage devices represented by lithium-ion batteries, by using a laminated packaging material in which resin films are laminated on both sides of an aluminum foil or the like instead of a metal can case, various shapes can be processed, and in addition, a thin and lightweight structure can be achieved.

[0003] In addition, the laminated battery packaging material is formed into a three-dimensional shape such as a substantially rectangular parallelepiped shape by deep drawing or bulging. By forming the battery packaging material into a three-dimensional shape, a storage space for accommodating electrodes and an electrolyte can be ensured.

[0004] In order to form the battery packaging material into a three-dimensional shape in a good state without pinholes, fractures, etc., it is required to improve the slidability of the surface of the inner heat-sealing resin layer (sealant layer). As a method for improving the slidability of the heat-sealing resin layer, addition of a lubricant to the resin has been carried out (see Patent Documents 1 to 3).

[0005] Patent Document 1 describes that slidability can be improved by using a sealant film containing a specific lubricant in a random copolymer of α-olefins having a specific composition as the heat-sealing resin layer.

[0006] Patent Document 2 describes that slidability can be improved and generation of white powder due to exudation of the lubricant can be prevented by using a sealant film added with a specified amount of saturated fatty acid amide and unsaturated fatty acid amide as the heat-sealing resin layer.

[0007] Patent Document 3 describes that slidability can be improved and generation of white powder due to exudation of the lubricant can be prevented by using a multi-layer sealant film of three or more layers as the heat-sealing resin layer and specifying the lubricant content of each layer.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent Publication No. 3774163

[0011] Patent Document 2: Japanese Patent Publication No. 6808966

[0012] Patent Document 3: Japanese Patent Publication No. 6943547 Summary of the Invention

[0013] Problems to be Solved by the Invention

[0014] In the technologies described in the above-mentioned documents, attention has been paid to the composition of the sealing film, the type and addition amount of the lubricant to improve the slidability during molding. Thus, the material of the heat-sealable resin layer of the battery packaging material has been improved only for the purpose of improving the slidability during molding.

[0015] The heat-sealable resin layer of the battery packaging material forms the inner surface of the battery case and is the layer in contact with the electrodes and the electrolyte, but the influence of the lubricant on the battery performance has not been studied in the past.

[0016] Means for Solving the Problems

[0017] In view of the above-mentioned background art, an object of the present invention is to improve the slidability during molding and suppress the deterioration of battery performance by using a specific lubricant in the heat-sealable resin layer of the battery packaging material.

[0018] That is, the present invention has the following configurations [1] to [7].

[0019] [1] A battery packaging material, characterized in that it is a battery packaging material comprising at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order from the outside to the inside.

[0020] The heat-sealable resin layer contains a polyolefin resin and one or more lubricants, and at least one lubricant is an N-substituted amide represented by the following formula (I).

[0021] [Chemical Formula 1]

[0022]

[0023] R1 is a hydrocarbon chain represented by C m1 H n1 represented hydrocarbon chain

[0024] R2 is a hydrocarbon chain represented by C m2 H n2 represented hydrocarbon chain

[0025] [2] The battery packaging material according to the previous item 1, wherein the N-substituted amide has 34 or more carbon atoms, and the number of carbon atoms (m1) of R1 and the number of carbon atoms (m2) of R2 satisfy the relationship of |m1 - m2| ≤ 15.

[0026] [3] The battery packaging material according to the previous item 1 or 2, wherein the heat-sealable resin layer is a single layer or a multi-layer of two or more layers, the innermost layer contains an N-substituted amide, and the total concentration of all the lubricants containing the N-substituted amide in the innermost layer is 100 mass ppm to 2500 mass ppm.

[0027] [4] The battery packaging material according to any one of the preceding items 1 to 3, wherein the hot-melt adhesive resin layer contains an unsaturated fatty acid amide as a lubricant.

[0028] [5] The battery packaging material according to item 3 or 4 of the preceding items, wherein the proportion of the N-substituted amide in the innermost layer of the hot-melt adhesive resin layer is 30% by mass to 100% by mass based on the total amount of the lubricant.

[0029] [6] The battery packaging material according to any one of the preceding items 1 to 5, wherein a lubricant layer containing an N-substituted amide is formed on the surface of the hot-melt adhesive resin layer.

[0030] [7] A battery case member, characterized in that a recess obtained by deep drawing or bulging is formed in the battery packaging material according to any one of claims 1 to 6.

[0031] Advantages of the Invention

[0032] Regarding the battery packaging material described in [1] above, an N-substituted amide is included as a lubricant added to the hot-melt adhesive resin layer that forms the inner surface of the battery case. The lubricant precipitates on the layer surface, exhibiting the effect of improving the slidability. In deep drawing and bulging, deep forming can be achieved, and the battery capacity can be increased. Moreover, since hydrocarbon chains (aliphatic hydrocarbons) R1 and R2 are bonded to both ends of the amide group in the N-substituted amide, even if it dissolves in the electrolyte, it does not hinder the movement of lithium ions during charge and discharge, and can suppress the reduction of battery performance caused by the lubricant.

[0033] Regarding the battery packaging material described in [2] above, since the total number of carbon atoms of the N-substituted amide is 34 or more, and the number of carbon atoms (m1) of R1 and the number of carbon atoms (m2) of R2 satisfy the relationship |m1 - m2| ≤ 15, the influence of the amide group becomes smaller due to steric hindrance, and the intramolecular polarity becomes smaller. Therefore, the influence caused by the amide group hindering the movement of lithium ions can be reduced, and it has the effects of suppressing the increase in the internal resistance of the battery and improving the discharge rate.

[0034] Regarding the battery packaging material described in [3] above, since the hot-melt adhesive resin layer is single-layer or multi-layer, the innermost layer contains an N-substituted amide, and the total concentration of all lubricants containing the N-substituted amide is 100 ppm by mass to 2500 ppm by mass, the slidability is good, and the bleeding amount is also suppressed.

[0035] Regarding the battery packaging material described in [4] above, since the hot-melt adhesive resin layer contains an unsaturated fatty acid amide as a lubricant, excellent slidability can be obtained.

[0036] Regarding the battery packaging material described in the above [5], since the proportion of N-substituted amide in the innermost layer of the heat-sealable resin layer is 30% by mass to 100% by mass based on the total amount of the lubricant, the effects of improving the slidability and suppressing the reduction of battery performance can be obtained with good balance.

[0037] Regarding the battery packaging material described in the above [6], by forming a lubricant layer containing N-substituted amide on the surface of the heat-sealable resin layer, the effects of improving the slidability and suppressing the reduction of battery performance can be obtained.

[0038] Regarding the member for a battery case described in the above [7], since the heat-sealable resin layer on the inner surface of the concave portion contains N-substituted amide as a lubricant, deep drawing and bulging forming can be achieved, and the battery capacity can be increased. Moreover, even if it dissolves in the lubricant electrolyte, it does not hinder the movement of lithium ions during charge and discharge, and the reduction of battery performance caused by the lubricant can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a cross-sectional view showing an example of the battery packaging material of the present invention.

[0040] Figure 2 is a cross-sectional view showing another example of the battery packaging material of the present invention.

[0041] Figure 3 is a cross-sectional view showing still another example of the battery packaging material of the present invention.

[0042] Figure 4 is for Figure 1 The cross-sectional view of the battery case made of the battery packaging material. DETAILED DESCRIPTION OF THE INVENTION

[0043] Figures 1 to 3 An example and a modified example of the battery packaging material according to the present invention are shown.

[0044] In the following description, layers denoted by the same reference numerals represent the same or equivalent objects, and repeated descriptions are omitted.

[0045] [Battery Packaging Material]

[0046] The battery packaging material of the present invention is a laminate that at least includes a base material layer, a barrier layer, and a heat-sealable resin layer in this order from the outside to the inside as a basic configuration.

[0047] Figure 1 The battery packaging material 1 of​​​​

[0048] As Figure 4 shown, the above-mentioned battery packaging material 1 is processed into a main body 51 having a recess 52 and a flat lid 55. The heat-sealable resin layers 15 of both are arranged opposite to each other. The battery main body 56 is accommodated in the recess 52, and the flange portion 53 around the recess 52 is heat-sealed to the lid 55, thereby fabricating the battery case 50. In the battery case 50, the above-mentioned base material layer 13 is on the outside and the above-mentioned heat-sealable resin layer 15 is on the inside. Therefore, in the present invention, when the positions of the respective layers constituting the battery packaging material are described in terms of directions, the direction on the base material side is referred to as the outside and the direction of the heat-sealable resin layer is referred to as the inside according to the inside and outside directions of the case.

[0049] Regarding the battery packaging material 1 of the present invention, by using a specific lubricant in the heat-sealable resin layer 15 that forms the inner surface of the case 50 and contacts the battery main body 56, the slidability during molding can be improved, and a decrease in battery performance can be prevented.

[0050] Hereinafter, each layer constituting the above-mentioned battery packaging material 1 will be described in detail.

[0051] (Heat-sealable resin layer)

[0052] The heat-sealable resin layer 15 also has excellent chemical resistance against highly corrosive electrolytes and the like, and plays a role of imparting heat-sealability to the battery packaging material 1.

[0053] The above-mentioned heat-sealable resin layer 15 contains a polyolefin resin and one or more lubricants, and at least one lubricant is an N-substituted amide represented by the following formula (I).

[0054] [Chemical formula 2]

[0055]

[0056] R1 is a hydrocarbon chain represented by C m1 H n1

[0057] R2 is a hydrocarbon chain represented by C m2 H n2

[0058] The lubricant improves the slidability with the mold during molding. If the heat-sealable resin layer 15 is formed with a resin composition in which the resin and the lubricant are mixed, the lubricant precipitates on the layer surface, exerting the effect of improving the slidability. Therefore, deep drawing and bulging molding can be achieved, and the battery capacity can be increased.

[0059] ​​The aforementioned polyolefin resin may be exemplified by a polyethylene resin or a polypropylene resin, and a polypropylene resin is particularly preferred. As the polypropylene resin, an unstretched film such as cast polypropylene (CPP) or blown polypropylene (IPP) is preferred. As the aforementioned polypropylene resin, in addition to a homopolymer of propylene (hPP), an ethylene-propylene copolymer containing ethylene and propylene as copolymer components may be exemplified. The aforementioned ethylene-propylene copolymer may be either a random copolymer (rPP) or a block copolymer (bPP).

[0060] In addition, the heat-sealable resin layer may be either a single layer or a multilayer. Figure 1 The heat-sealable resin layer 15 of the battery packaging material 1 is a single layer. Figure 2 The heat-sealable resin layer 20 of the battery packaging material 2 is a three-layer structure. Figure 3 The heat-sealable resin layer 25 of the battery packaging material 3 is a two-layer structure. The multilayer film constituting the aforementioned multilayer heat-sealable resin layer can be produced by coextrusion or the like. In the case of a three-layer film, among the above-mentioned various polypropylene resin films, considering excellent heat-sealing properties, delamination resistance, and insulation properties, a three-layer coextruded CPP film with hPP or bPP as the intermediate layer and rPP layers arranged on both outer sides of the intermediate layer can be recommended. Figure 2 The heat-sealable resin layer 20 of the battery packaging material 2 is composed of a three-layer film with a laminated layer 22 adhered to the second adhesive layer 14 arranged on one surface of the intermediate layer 21 and a sealing layer 23 arranged on the other surface. Figure 3 The heat-sealable resin layer 25 of the battery packaging material 3 is a two-layer film of the laminated layer 22 and the sealing layer 23.

[0061] The aforementioned lubricant may use a variety of N-substituted amides under the condition of containing N-substituted amides, and other lubricants may also be used.

[0062] Examples of the N-substituted amide represented by the above formula (I) include N-oleyl palmitamide, N-stearyl stearamide, N-stearyl oleamide, N-oleyl stearamide, and N-stearyl erucamide. Table 1 shows the total number of carbon atoms, the number of carbon atoms of R1 (m1), and the number of carbon atoms of R2 (m2) of these N-substituted amides.

[0063] [Table 1]

[0064]

[0065] The N-substituted amide has hydrocarbon chains (aliphatic hydrocarbons) R1 and R2 bonded to both ends of the amide group. Therefore, even if it dissolves in the electrolyte, it does not hinder the movement of lithium ions during charge and discharge. In particular, it can prevent the performance degradation of lithium secondary batteries such as an increase in internal resistance and a decrease in discharge rate. On the other hand, in the case of erucic acid amide where the amide group is present at the end of the molecular chain, the amide group interacts with Li ions and easily forms non-covalent bonds, thus hindering the movement of Li ions.

[0066] Among the aforementioned N-substituted amides, amides with a total carbon atom number of 34 or more and the carbon atom number (m1) of R1 and the carbon atom number (m2) of R2 satisfying the relationship |m1 - m2| ≤ 15, that is, amides with the absolute value of m1 - m2 being 15 or less, are preferably used. For N-substituted amides satisfying this condition, due to steric hindrance, the influence of the amide group becomes smaller and the intramolecular polarity becomes smaller. Therefore, the influence caused by the amide group hindering the movement of lithium ions can be reduced. Specifically, the effect of suppressing the increase in the internal resistance of the battery and improving the discharge rate is large.

[0067] The heat-sealable resin layer is single-layer or multi-layer. In order to achieve an improvement in slidability and suppress the degradation of battery performance, it is preferable to contain N-substituted amide in the innermost layer and to specify the total concentration of all lubricants containing N-substituted amide in the innermost layer. The innermost layer refers to the layer that forms the inner surface of the battery case 50 and contacts the corresponding material during heat sealing. Figure 2 of the three-layer heat-sealable resin layer 20 or Figure 3 the innermost layer of the two-layer heat-sealable resin layer 25 is the sealing layer 23. In the case of a single layer, the entire heat-sealable resin layer 15 is the innermost layer. The total concentration of all lubricants in the innermost layer is preferably 100 mass ppm to 2500 mass ppm. When it is less than 100 mass ppm, good slidability cannot be obtained. If it exceeds 2500 mass ppm, the amount of exudation increases, and the lubricant may precipitate in a powdery white form on the surface of the innermost layer and adhere to the molding die and the production line. When it is 2500 mass ppm or less, the amount of exudation is suppressed. The particularly preferred total concentration of all lubricants in the innermost layer is 200 mass ppm to 2000 mass ppm.

[0068] The lubricant added to the innermost layer described above may be only N-substituted amide, or other lubricants may be used in combination. When using other lubricants in combination, in order to prevent a decrease in battery performance, it is preferable that the proportion of N-substituted amide in the innermost layer of the heat-sealable resin layer is 30% by mass or more based on the total amount of lubricants. If the proportion of N-substituted amide is less than 30% and the proportion of other lubricants increases, the other lubricants dissolved in the electrolyte may hinder the movement of lithium ions during charge and discharge, resulting in a decrease in battery performance. Therefore, the preferable proportion of N-substituted amide in the innermost layer is 30% to 100% by mass based on the total amount of lubricants. The particularly preferable proportion of N-substituted amide in the innermost layer is 40% by mass or more. The names of the lubricants used in combination with N-substituted amide will be described in detail later.

[0069] In addition, in the multi-layer heat-sealable resin layer, when adding N-substituted amide or other lubricants to the layers other than the innermost layer, it is preferable to increase or decrease the concentration of other layers based on the total concentration of all lubricants containing N-substituted amide in the innermost layer as the reference concentration.

[0070] In Figure 2 In the three-layer heat-sealable resin layer 20 of , taking the total concentration of all lubricants in the innermost layer, i.e., the sealing layer 23, as the reference concentration, it is preferable that the concentration of the intermediate layer 21 is 1000 ppm or more and 2 times or less of the reference concentration, and the concentration of the laminated layer 22 is 1 / 2 or less (including 0 mass ppm) of the reference concentration. By making the N-substituted amide concentration in the intermediate layer 21 higher than that in the sealing layer 23, the migration of N-substituted amide in the sealing layer 26 to the intermediate layer 21 can be suppressed, and the exudation of N-substituted amide to the surface of the sealing layer 23 can be promoted. In addition, by making the N-substituted amide concentration in the laminated layer 21 lower than that in the sealing layer 23, the exudation of N-substituted amide to the laminated layer / adhesive layer interface can be suppressed, and the decrease in lamination strength can be prevented. In Figure 3 In the three-layer heat-sealable resin layer 25 of , taking the total concentration of all lubricants in the sealing layer 23 as the reference concentration, it is preferable that the lubricant concentration of the laminated layer 22 is 1 / 2 or less of the reference concentration.

[0071] Examples of the lubricants used in combination with N-substituted amide include hydroxymethylamide, saturated fatty acid amide, saturated fatty acid bisamide, unsaturated fatty acid bisamide, fatty acid ester amide, and aromatic bisamide. Among these lubricants, fatty acid amide, especially unsaturated fatty acid amide, which has a greater effect of improving the sliding property compared with N-substituted amide, is recommended.

[0072] As hydroxymethylamide, hydroxymethyl stearamide can be used.

[0073] As saturated fatty acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide can be used.

[0074] As the saturated fatty acid bisamide, methylene bisstearamide, ethylene bisdecanoamide, ethylene dilauramide, ethylene bisstearamide, ethylene bis(hydroxystearamide), ethylene bisbehenamide, hexamethylene bisstearamide, hexamethylene bisbehenamide, hexamethylene hydroxystearamide, N,N'-distearyl adipamide, N,N'-distearyl sebacamide can be used.

[0075] As the unsaturated fatty acid bisamide, oleamide, erucamide, ethylene bisoleamide, ethylene biserucamide, hexamethylene bisoleamide, N,N'-dioleyl adipamide, N,N'-dioleyl sebacamide can be used.

[0076] As the fatty acid ester amide, stearamide ethyl stearate can be used.

[0077] As the aromatic bisamide, m-phenylene bisstearamide, m-phenylene bis(hydroxystearamide), N,N'-distearyl isophthalamide can be used.

[0078] The lubricant added to the aforementioned hot melt adhesive resin layer 15 precipitates on the layer surface, thereby improving the slidability. The preferred amount of the lubricant precipitated on the layer surface is 0.1 μg / cm 2 ~1 μg / cm 2 .

[0079] In the aforementioned hot melt adhesive resin layer 15, in addition to the lubricant, solid particles can also be added as an anti-blocking material for preventing adhesion to the substrate layer 13 and a roughening material for improving the slidability. Examples of the aforementioned solid particles include silica, alumina, calcium carbonate, barium carbonate, titanium oxide, aluminum silicate, talc, kaolin, acrylic resin beads, polyethylene resin beads, etc. When these solid particles are used as the anti-blocking material, the preferred average particle size is 0.05 μm to 5 μm, and the preferred content is 500 ppm to 3500 ppm. In addition, when used as the roughening material, the preferred average particle size is greater than 5 μm and 20 μm or less, and the preferred content is 200 ppm to 5000 ppm.

[0080] The aforementioned roughening material is an ingredient added to form unevenness on the layer surface. Therefore, in the multi-layer heat-sealable resin layers 20 and 25, it is only necessary to add it to the innermost layer, i.e., the sealing layer 23, and it should not be added to the laminated layer 22 on the barrier layer 11 side. In addition, the preferred average particle size of the roughening material is greater than 5 μm and 20 μm or less. Therefore, the thickness of the layer to which the roughening material is added is preferably in the range of 5 μm to 20 μm. If it is added to a layer with a thickness less than 5 μm, the roughening material is likely to fall off. On the other hand, if the layer thickness is greater than 20 μm, the portion of the roughening material with an average particle size greater than 5 μm and 20 μm or less buried in the resin increases. As a result, the rigidity of the film may be impaired. In addition, the dispersion of the roughening material in the layer becomes uneven, so the impact resistance and interlayer strength may decrease.

[0081] The dynamic friction coefficient of the aforementioned heat-resistant resin layers 15, 20, and 25 is preferably 0.02 to 0.3. When the dynamic friction coefficient is less than 0.02, the sliding property is too good, and winding deviation and meandering of the battery packaging material are likely to occur on the production line. On the other hand, if the dynamic friction coefficient is greater than 0.3, the sliding property decreases, and the effect of improving the formability cannot be expected.

[0082] The thickness of the aforementioned heat-sealable resin layer 15 is preferably 20 μm to 120 μm. The total thickness of the multi-layer films 20 and 25 is also the same. The particularly preferred thickness is 30 μm to 80 μm.

[0083] In addition, it is also preferred to form a lubricant layer containing N-substituted amide on the surface of the aforementioned heat-sealable resin layers 15, 20, and 25. The aforementioned lubricant layer is the total amount of the lubricant layer formed by precipitation from the heat-sealable resin layer and the lubricant layer formed by coating and transfer from the substrate layer 13. Through this lubricant layer, the effects of improving the sliding property and suppressing the reduction of battery performance can also be obtained. The aforementioned lubricant layer can be a layer that completely covers the surface of the heat-sealable resin layers 15, 20, and 25, or a layer in which the lubricant intermittently exists on the surface of the heat-sealable resin layers 15, 20, and 25. In addition, the preferred amount of lubricant in the aforementioned lubricant layer is 0.15 μg / cm 2 ~0.6 μg / cm 2 。

[0084] (Barrier layer)

[0085] The foregoing barrier layer 11 functions to impart gas barrier properties to the battery packaging material 1 to prevent the intrusion of oxygen and moisture. As the foregoing barrier layer 11, there is no particular limitation as long as it is a metal foil. For example, aluminum foil, SUS foil (stainless steel foil), copper foil, nickel foil, titanium foil, and coated foil can be cited, and aluminum foil is preferably used. The thickness of the foregoing barrier layer 11 is preferably 10 μm to 120 μm. By being 10 μm or more, pinholes generated during rolling when manufacturing the metal foil can be prevented, and by being 120 μm or less, the stress during forming such as bulging forming and deep drawing forming can be reduced, and the formability can be improved. A particularly preferred thickness of the foregoing barrier layer 11 is 30 μm to 90 μm.

[0086] In addition, for the foregoing barrier layer 11, it is preferable to perform substrate treatment such as chemical conversion treatment on at least one surface on the side of the heat-sealable resin layer 15 of the foregoing metal foil. By performing such chemical conversion treatment, corrosion of the metal foil surface caused by the contents (such as the electrolyte of the battery) can be sufficiently prevented.

[0087] (Base material layer)

[0088] For the foregoing base material layer 13, a heat-resistant resin film that does not melt at the heat-sealing temperature when heat-sealing the battery packaging material 1 is used. As the foregoing heat-resistant resin, a heat-resistant resin having a melting point 10 °C or more, preferably 20 °C or more higher than the melting point of the resin constituting the heat-sealable resin layer 15 is used. As the resin satisfying this condition, for example, polyamide films such as nylon films, polyester films, etc. can be cited, and their stretched films are preferably used. Among them, as the foregoing base material layer 13, biaxially stretched polyamide films such as biaxially stretched nylon films, biaxially stretched polybutylene terephthalate (PBT) films, biaxially stretched polyethylene terephthalate (PET) films, or biaxially stretched polyethylene naphthalate (PEN) films are particularly preferably used. As the foregoing nylon film, there is no particular limitation. For example, nylon 6 film, nylon 6,6 film, nylon MXD film, etc. can be cited. The foregoing base material layer 13 can be formed of a single layer, or can also be formed by, for example, a multilayer formed of a polyester film / polyamide film (such as a multilayer formed of a PET film / nylon film).

[0089] The thickness of the foregoing base material layer 13 is preferably 9 μm to 50 μm, which can ensure sufficient strength as a packaging material, and can reduce the stress during forming such as bulging forming and deep drawing forming, and can improve the formability. A further preferred thickness of the foregoing base material layer 13 is 9 μm to 30 μm. When the base material layer 13 is multilayered, the total thickness is set to the above thickness. In addition, the thickness of the adhesive for laminating multiple layers is also included in the above thickness.

[0090] (First adhesive layer)

[0091] As the aforementioned first adhesive layer 12, there is no particular limitation. For example, an adhesive layer formed of a two-component curable adhesive can be cited. As the aforementioned two-component curable adhesive, for example, a two-component curable adhesive composed of a first liquid (main agent) containing one or two or more polyols selected from the group consisting of polyurethane-based polyols, polyester-based polyols, polyether-based polyols, and polyesterurethane-based polyols, and a second liquid (curing agent) containing isocyanate can be cited. Among them, a two-component curable adhesive composed of a first liquid containing one or two or more polyols selected from the group consisting of polyester-based polyols and polyesterurethane-based polyols, and a second liquid (curing agent) containing isocyanate is preferably used. The preferred thickness of the aforementioned first adhesive layer 12 is 2 μm to 5 μm.

[0092] In addition, in the case where the aforementioned outer layer is composed of multiple layers (including the case where the base material layer is multiple layers), the above-mentioned adhesive is also recommended.

[0093] (Second adhesive layer)

[0094] As the aforementioned second adhesive layer 14, there is no particular limitation. For example, an adhesive containing one or more of polyurethane-based resins, acrylic-based resins, epoxy-based resins, polyolefin-based resins, elastic system resins, fluorine-based resins, and acid-modified polypropylene resins can be recommended. Among them, an adhesive formed of a polyurethane composite resin with acid-modified polyolefin as the main agent is preferably used. The preferred thickness of the aforementioned second adhesive layer 14 is 2 μm to 5 μm.

[0095] The aforementioned first adhesive layer 12 and second adhesive layer 14 are not essential layers. The base material layer 13 can be directly adhered to the barrier layer 11. In addition, the heat-sealable resin layer 15 can be directly adhered to the barrier layer 11.

[0096] A layer can be added to the outside of the base material layer 13 of the battery packaging material 1 of the present invention. For example, a base material protective layer composed of a resin composition containing a resin component and solid particles can be formed to impart slidability to one side of the outside, thereby improving formability and being able to impart excellent chemical resistance, solvent resistance, and abrasion resistance.

[0097] The preferred materials of the resin composition constituting the aforementioned base material protective layer are as described below.

[0098] As the aforementioned resin component, at least one resin selected from acrylic-based resins, epoxy-based resins, urethane-based resins, polyolefin-based resins, fluorine-based resins, and phenoxy resins is preferably used. These resins have high chemical resistance and solvent resistance, so the shedding of solid particles caused by resin deterioration and the like is not likely to occur.

[0099] In addition, the resin component may be a main agent resin containing at least one of the above-mentioned resins and a curing agent for curing the main agent resin. The curing agent is not particularly limited and can be appropriately selected according to the main agent resin. For example, when the main agent resin is a mixture of a urethane-based resin and a phenoxy-based resin, an isocyanate compound is preferably used. Various polyfunctional isocyanate compounds of aliphatic, alicyclic, and aromatic series can be recommended for the isocyanate compound. As the aliphatic polyfunctional isocyanate compound, hexamethylene diisocyanate (HDI) etc. can be cited, as the alicyclic polyfunctional isocyanate compound, isophorone diisocyanate (IPDI) etc. can be cited, and as the aromatic polyfunctional isocyanate compound, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) etc. can be cited. In addition, it may be a modified product of these polyfunctional isocyanate compounds, and polyfunctional isocyanate modified products obtained by polycondensation reactions such as isocyanuration, carbodiimidation, and polymerization can be exemplified.

[0100] It is preferable to blend 5 to 30 parts by mass of the aforementioned curing agent with respect to 100 parts by mass of the aforementioned main agent resin. When it is less than 5 parts by mass, the adhesion to the base material layer 13 and the solvent resistance may decrease. In addition, if it exceeds 30 parts by mass, the base material protective layer 30 may become hard and the moldability may decrease. The blending amount of the curing agent that is particularly preferable is 10 to 20 parts by mass with respect to 100 parts by mass of the aforementioned main agent resin.

[0101] The base material protective layer has a smaller shrinkage rate than the film constituting the base material layer 13, and thus can reduce the stress generated due to the expansion and contraction of the outer layer toward the base material layer 13 side. In addition, especially when a polyamide film is used in the base material layer 13, polyamide has the property of being easily shrunk in moisture, but since the base material protective layer 30 blocks the moisture in the air, it becomes less likely to shrink, and the stress toward the outer layer can also be suppressed.

[0102] In addition, as the main agent, it is also preferable to use a urethane-based resin and a polyester urethane-based resin.

[0103] The aforementioned solid particles can be used in any form of inorganic particles and organic particles, or they can be mixed and used. As the inorganic particles, silica, alumina, calcium oxide, calcium carbonate, calcium sulfate, calcium silicate, carbon black etc. can be exemplified, and as the organic particles, particles such as acrylate-based compounds, polystyrene-based compounds, epoxy-based resins, polyamide-based compounds, or their crosslinked products can be used. The aforementioned solid particles can be used singly or two or more kinds can be mixed and used.

[0104] For these solid particles, solid particles with an average particle size of 1 μm to 10 μm are preferably used, and those with a particle size of 2 μm to 5 μm are more preferably used. When using solid particles with a particle size smaller than 1 μm which are too small, they will be buried in the coating liquid and it is difficult to obtain the desired properties. On the other hand, when using solid particles with a particle size larger than 10 μm which are too large, the particle size exceeds the coating thickness and it is easy to fall off from the substrate protective layer.

[0105] In addition, the content of the solid particles in the resin composition is preferably in the range of 0.1% by mass to 60% by mass, and more preferably in the range of 5% by mass to 55% by mass.

[0106] The thickness of the cured substrate protective layer is preferably 1 to 10 μm. In the case of a layer thinner than the lower limit value, the effect of improving the slidability is small, and in the case of a layer thicker than the upper limit value, the cost increases. The particularly preferred thickness is in the range of 2 to 5 μm.

[0107] [Component for battery case]

[0108] The component for battery case of the present invention has a recess formed by deep drawing or bulging the above-mentioned packaging material for battery. Figure 4 The main body 51 having the recess 52 corresponds to the component for battery case of the present invention. Since the packaging material for battery of the present invention has good slidability and excellent formability of the heat-sealable resin layer, it is advantageous for the formation of the recess 52 and is suitable for the formation of deep recesses. By forming deep recesses, the accommodation space for the battery main body is expanded, thereby enabling an increase in battery capacity. In addition, since the inner surface of the recess is a heat-sealable resin layer added with N-substituted amide, a decrease in battery performance can be suppressed.

[0109] Examples

[0110] [Packaging material for battery]

[0111] As Examples 1, 2, 4 to 7 and Comparative Examples 1, 2, the battery packaging materials 2 in the Figure 2 laminated form were fabricated. As Example 3, the battery packaging material 1 in the Figure 1 laminated form was fabricated. For these battery packaging materials 1 and 2, they are common in that a substrate layer 13, a first adhesive layer 12, a barrier layer 11, and a second adhesive layer 14 are laminated in sequence from the outside to the inside, and the number of heat-sealable resin layers 15, 20 laminated on the inside of the second adhesive layer 14 is different. The heat-sealable resin layer 15 of the battery packaging material 1 is a single layer, and the heat-sealable resin layer 20 of the battery packaging material 2 is three layers, namely a sealing layer 23, an intermediate layer 21, and a laminated layer 22 (see Table 2).

[0112] The common materials in the battery packaging materials 1 and 2 of each example are as follows.

[0113] (Common material)

[0114] As the barrier layer 11, an aluminum foil formed of A8021-O specified in JIS H4160 and having a thickness of 40 μm is used. A product obtained by coating both sides of the aforementioned aluminum foil with a chemical conversion treatment liquid containing phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol, and then drying at 180°C to form a chemical conversion film is used. The chromium adhesion amount of the chemical conversion film is 5 mg / m per side 2 .

[0115] As the base material layer 13, a biaxially stretched nylon 6 film with a thickness of 25 μm is used.

[0116] As the first adhesive layer 12, a two-component curable urethane-based adhesive is used.

[0117] As the second adhesive layer 14, a two-component curable maleic acid-modified propylene adhesive is used.

[0118] (Production of the film for the heat-sealable resin layer)

[0119] As the single-layer heat-sealable resin layer 15 of Example 3, two kinds of lubricants described in Table 3 and silica having an average particle size of 2 μm as an anti-blocking material (AB material) were compounded in an ethylene-propylene random copolymer (rPP) to produce an unstretched PP film with a thickness of 30 μm. The names of the lubricants, the concentrations of the lubricants, and the content of the anti-blocking material are shown in Table 3.

[0120] As the heat-sealable resin layer 20 of Examples 1, 2, 4 to 7 and Comparative Examples 1 and 2, a three-layer film was produced.

[0121] The sealant layer 23 is formed by compounding one or two kinds of lubricants shown in Table 3, silica having an average particle size of 2 μm as an anti-blocking material (AB material), and HDPE beads having an average size of 12 μm as a roughening material in an ethylene-propylene random copolymer (rPP). The intermediate layer 21 is formed by compounding one or two kinds of lubricants shown in Table 3 in an ethylene-propylene block copolymer (bPP). The laminated layer 22 is formed by compounding the lubricants shown in Table 3 and silica having an average particle size of 2 μm as an anti-blocking material in an ethylene-propylene random copolymer (rPP). The names of the lubricants, the concentrations of the lubricants, the content of the anti-blocking material, and the content concentration of the roughening material in each layer are shown in Table 3.

[0122] The mixed materials of the above-mentioned respective layers were co-extruded to produce a three-layer film with a thickness of 12 μm for the sealant layer 23, a thickness of 56 μm for the intermediate layer 21, a thickness of 12 μm for the laminated layer 22, and a total thickness of 80 μm.

[0123] Table 2 shows the total concentration (mass ppm) of all lubricants, the N-substituted amide concentration (mass ppm), and the ratio (mass %) of the N-substituted amide in the innermost layer to the total amount of lubricants in the innermost layers of the heat-sealable resin layers 15 and 20. For the single-layer heat-sealable resin layer 15, the heat-sealable resin layer 15 itself is the innermost layer, and the innermost layer of the three-layer heat-sealable resin layer 20 is the sealing layer 23.

[0124] [Table 2]

[0125]

[0126] [Table 3]

[0127]

[0128] (Manufacture of Battery Packaging Materials)

[0129] For the single-layer film for the heat-sealable resin layer 15 produced, one surface is subjected to corona treatment. Further, for the three-layer film for the multi-layer heat-sealable resin layer 20, the surface of the laminate layer 22 is subjected to corona treatment.

[0130] A first adhesive layer 12 with a thickness of 3 μm is formed on one surface of the barrier layer 11 formed with a chemical conversion film, and dry lamination is performed on the substrate layer 13. Then, a second adhesive layer 14 with a thickness of 2 μm is formed on the other surface of the barrier layer 11, and the corona-treated surface of the single-layer heat-sealable resin layer 15 or the laminate layer 22 (corona-treated surface) of the multi-layer heat-sealable resin layer 20 is laminated on the second adhesive layer 14, and press bonding is performed while sandwiching between lamination rollers heated to 100 °C, thereby performing dry lamination to produce a laminate, which is wound around a reel.

[0131] The laminate wound around the reel is cured at 40 °C for 10 days to produce battery packaging materials 1 and 2.

[0132] [Evaluation of Battery Packaging Materials]

[0133] The slidability of the produced battery packaging materials 1 and 2 is evaluated using the coefficient of kinetic friction measured by the following method, and the formability is evaluated using the maximum forming depth measured by the following method. In addition, for the performance of the battery using the case made of these battery packaging materials, evaluation is performed using the following method. The evaluation results are shown in Table 4.

[0134] (Coefficient of Kinetic Friction)

[0135] Based on JIS K7125:1999, the dynamic friction coefficient between the heat-sealable resin layers 15 and 20 of the battery packaging materials 1 and 2 was measured using the Toyo Seiki friction tester TR type. A case where the dynamic friction coefficient is 0.45 or less was regarded as qualified.

[0136] (Formability)

[0137] The fabricated battery packaging materials 1 and 2 were cut into 100 mm × 150 mm as raw materials for forming. Then, a deep drawing die equipped with a die, a punch, and a blank holder was installed on a servo press, and deep drawing forming was performed into a rectangular parallelepiped shape with a length of 55 mm × a width of 35 mm × a depth of D. The aforementioned deep drawing forming was carried out at a forming speed of 20 spm in such a manner that the top surface of the punch contacted the heat-sealable resin layers 15 and 20 of the forming raw material and the base material layer 13 protruded outward, and the forming depth D was changed in units of 0.5 mm.

[0138] Then, the corners of the formed product were illuminated, and visual observation was made for transmitted light due to pinholes or cracks. The maximum forming depth (mm) at which good forming without pinholes and cracks could be achieved was investigated. Based on the following judgment criteria, the formability was evaluated by the maximum forming depth, and AB was regarded as qualified.

[0139] A: The maximum forming depth is 7 mm or more

[0140] B: The maximum forming depth is 6 mm or more and less than 7 mm

[0141] C: The maximum forming depth is 5 mm or more and less than 6 mm

[0142] D: The maximum forming depth is less than 5 mm

[0143] (Battery performance)

[0144] As the battery case of the evaluation battery, a forming blank with a length of 140 mm × a width of 55 mm was sampled from the battery packaging materials 1 and 2, and deep drawing forming was performed on one half (length 70 mm × width 55 mm) of the forming blank to form a rectangular parallelepiped-shaped recess with a length of 55 mm × a width of 35 mm × a depth of 4 mm. Then, the other part (non-forming part) of the forming blank was bent to be used as the cover material part, and a battery case was fabricated.

[0145] As the material for the battery body to be housed in the aforementioned battery case, the following positive electrode plate and negative electrode plate were fabricated, and a non-aqueous electrolyte was prepared.

[0146] Positive electrode plate:

[0147] To 90 g of LiCoO2 as the positive electrode active material, 5 g of carbon black (manufactured by TIMCAL) as the conductive additive, and 5 g of polyvinylidene fluoride (PVdF) as the binder material, N-methyl-pyrrolidone was appropriately added while stirring and mixing to obtain a paste-like positive electrode paste. The aforementioned positive electrode paste was coated on an aluminum foil with a thickness of 20 μm using a roll coater, dried, and the paste was cured. For the dried sheet, the positive electrode active material density was made 3.6 g / cm 3 , and a positive electrode sheet was obtained.

[0148] Negative electrode sheet:

[0149] As the negative electrode active material, artificial graphite particles and carbon-coated SiO2 particles were used, and they were mixed at a mass ratio of 4:1 to prepare a mixed negative electrode active material. As the conductive additive, carbon black and vapor-grown carbon fiber (VGCF (registered trademark)-H, manufactured by Showa Denko K.K.) were used, and they were mixed at a mass ratio of 3:2 to prepare a mixed conductive additive. As the binder, styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were used. The aforementioned styrene-butadiene rubber (SBR) was dispersed in purified water to prepare an SBR dispersion. The aforementioned carboxymethyl cellulose (CMC) was mixed with purified water and stirred for a whole day and night using a stirrer to prepare a CMC solution.

[0150] 90 parts by mass of the aforementioned mixed negative electrode active material, 5 parts by mass of the aforementioned mixed conductive additive, the SBR dispersion containing 2.5 parts by mass of the solid component, and the CMC solution containing 2.5 parts by mass of the solid component were mixed, and an appropriate amount of water was further added to adjust the viscosity, and kneading was performed using a rotation-revolution mixer to obtain a negative electrode paste. The aforementioned negative electrode paste was uniformly coated on a copper foil with a thickness of 20 μm so that the thickness became 150 μm using a doctor blade, dried using a heating plate, and then vacuum dried. For the dried sheet, it was pressed using a uniaxial press at a pressure of 3 ton / cm 2 , and a negative electrode sheet was obtained.

[0151] Generally, when manufacturing a lithium-ion battery by opposing a positive electrode sheet and a negative electrode sheet, it is necessary to consider the capacity balance between the two. That is, if the negative electrode on the side receiving lithium ions is too small, excess Li will precipitate on the negative electrode side and become a cause of cycle degradation. Conversely, if the negative electrode is too much, since charging and discharging will occur in a state of low load, the cycle characteristics will be improved, but the energy density will be reduced.

[0152] In the production of the above-mentioned negative electrode sheet, in order to prevent the above-mentioned adverse conditions, the same sheet is used for the positive electrode sheet. For the negative electrode sheet, the discharge capacity per unit weight of the active material is evaluated in advance using a half-cell with respect to the counter electrode Li, and the capacity of the negative electrode sheet is finely adjusted so that the ratio of the capacity (QA) of the negative electrode sheet to the capacity (QC) of the positive electrode sheet becomes a constant value of 1.2.

[0153] Non-aqueous electrolyte:

[0154] In a non-aqueous solvent in which ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate are mixed at a volume ratio of 3:5:2, 1% by mass of vinylene carbonate (VC) and 5% by mass of fluoroethylene carbonate (FEC) are mixed as additives. The electrolyte LiPF6 is dissolved therein to a concentration of 1 mol / L to prepare a non-aqueous electrolyte.

[0155] Fabrication of evaluation battery:

[0156] Inside a glove box maintaining a dry argon atmosphere with a dew point of -80°C or lower, an evaluation battery is fabricated through the following steps.

[0157] The aforementioned positive electrode sheet and negative electrode sheet are punched to obtain a positive electrode sheet and a negative electrode sheet with an area of 20 cm 2 . Separately, an Al tab is attached to the aluminum foil of the aforementioned positive electrode sheet, and an Ni tab is attached to the copper foil of the negative electrode sheet. A polypropylene microporous membrane is sandwiched between the aforementioned positive electrode sheet and negative electrode sheet, and it is inserted into the concave portion of the battery case in a state where the Al tab and Ni tab are led out from one side of the battery case, and 0.5 mL of non-aqueous electrolyte is injected. Then, the opening of the battery case is sealed by heat welding to obtain an evaluation battery.

[0158] For the fabricated evaluation battery, using the Al tab and Ni tab, the internal resistance and discharge rate are measured using a HIOKI electrode resistance value measurement system RM2610, and thus the battery performance is evaluated.

[0159] Regarding the internal resistance, the DCR at a charge rate (SOC) of 20% and 80% is measured, and a value less than 6 Ω is regarded as qualified.

[0160] The discharge rate (%) is the ratio (%) of the discharge capacity when discharging at 1C or 3C with respect to a discharge capacity of 100%. The charging conditions are set to CC = 0.5C, CV = 4.2V, 0.05C cut-off, and the discharge conditions are set to CC = 0.5C, EV = 2.8V. Regarding the discharge rate at 1C, a value of 70% or more is regarded as qualified, and regarding the discharge rate at 3C, a value of 18% or more is regarded as qualified.

[0161] [Table 4]

[0162]

[0163] It can be confirmed from Table 4 that the slidability and moldability of the battery packaging materials of the examples are good, and in the batteries using these battery packaging materials as the housing, a decrease in battery performance is suppressed.

[0164] Industrial applicability

[0165] The battery packaging material of the present invention can be suitably used as a housing material for secondary batteries such as in-vehicle, stationary, laptop computer, mobile phone, and camera.

[0166] This application claims the priority of Japanese Patent Application No. 2022-194657 filed on December 6, 2022, the disclosure of which is directly incorporated herein by reference.

[0167] The terms and expressions used herein are for illustrative purposes and not for limiting interpretation, and do not exclude any equivalents of the features disclosed and described herein, and it should be understood that various modifications within the scope claimed in the present invention are permitted.

[0168] Description of reference numerals

[0169] 1, 2, 3... Battery packaging material

[0170] 11... Barrier layer

[0171] 12... First adhesive layer

[0172] 13... Substrate layer

[0173] 14... Second adhesive layer

[0174] 15... Heat-sealable resin layer (innermost layer)

[0175] 20, 25... Heat-sealable resin layer

[0176] 21... Intermediate layer

[0177] 22... Laminated layer

[0178] 23... Sealing layer (innermost layer)

[0179] 50... Battery housing

[0180] 51... Main body (member for battery housing)

[0181] 52... Recess

Claims

1. A packaging material for a battery, characterized in that, It is a battery packaging material that sequentially includes at least a base material layer, a barrier layer, and a heat-sealable resin layer from the outside to the inside. The heat-sealable resin layer contains a polyolefin resin and one or more lubricants, and at least one lubricant is an N-substituted amide represented by the following formula (I). [Chemical formula 3] R1 is C m1 H n1 a hydrocarbon chain represented by R2 is C m2 H n2 representing a hydrocarbon chain.

2. The packaging material for a battery according to claim 1, wherein, The N-substituted amide has 34 or more carbon atoms, and the number of carbon atoms (m1) of R1 and the number of carbon atoms (m2) of R2 satisfy the relationship |m1 - m2| ≤ 15.

3. The packaging material for a battery according to claim 1 or 2, wherein The heat-sealable resin layer is a single layer or a multi-layer of two or more layers. The innermost layer contains an N-substituted amide, and the total concentration of all lubricants containing the N-substituted amide in the innermost layer is 100 mass ppm to 2500 mass ppm.

4. The battery packaging material according to any one of claims 1 to 3, wherein, The heat-sealable resin layer contains an unsaturated fatty acid amide as a lubricant.

5. The packaging material for a battery according to any one of claims 1 to 4, wherein, The proportion of the N-substituted amide in the innermost layer of the heat-sealable resin layer relative to the total amount of lubricants is 30 mass% to 100 mass%.

6. The packaging material for a battery according to any one of claims 1 to 5, wherein, A lubricant layer containing an N-substituted amide is formed on the surface of the heat-sealable resin layer.

7. A component for a battery housing, characterized in that, In the battery packaging material according to any one of claims 1 to 6, a recess obtained by deep drawing or bulging is formed.

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