Secondary battery and manufacturing method thereof

Abstract

This secondary battery has a stack formed by laminating a positive electrode, a separator, and a negative electrode in said order. When a bonding surface X between the positive electrode and the separator and / or a bonding surface Y between the negative electrode and the separator is defined as a surface Z, and the length of a connection side of a positive electrode tab connected to the positive electrode or that of a negative electrode tab connected to the negative electrode is defined as L, within the surface Z, a rectangular region P, which has one pair of opposite sides defined by the connection side and a line segment located at a distance of 0.3 L from the connection side, has a greater resistance A per unit area than the resistance B per unit area in the region Q other than the region P.

Description

[Technical Field]

[0001] The present invention relates to a secondary battery and a method for manufacturing the same. [Background technology]

[0002] Secondary batteries such as lithium-ion secondary batteries are small, lightweight, have high energy density, and can be repeatedly charged and discharged, and are therefore used in a wide range of applications. Secondary batteries generally include battery components such as a positive electrode, a negative electrode, and a separator that separates the positive electrode from the negative electrode to prevent short circuits between the positive electrode and the negative electrode.

[0003] Known secondary battery structures include a stacked type in which a positive electrode, a separator, and a negative electrode are alternately stacked, and a wound type in which a long positive electrode, a separator, and a negative electrode are stacked and wound concentrically, etc. Among these, stacked secondary batteries have been attracting attention in recent years due to their excellent energy density, safety, quality, and durability.

[0004] When manufacturing a secondary battery, for example, a battery component having an adhesive material on its surface is manufactured, and the battery component is then bonded to another battery component. The battery component having an adhesive material on its surface can be produced by applying an adhesive composition (slurry for secondary batteries) made by dispersing and / or dissolving an adhesive polymer (binder) or the like in a solvent onto the surface of the battery component, and then drying the applied composition (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-27945 Summary of the Invention [Problem to be solved by the invention]

[0006] Here, in secondary batteries, metals such as lithium may be deposited on the electrode surfaces during charging. In particular, in large batteries such as those for automotive applications, when the secondary battery has electrode tabs, such as a positive electrode tab connected to the positive electrode and a negative electrode tab connected to the negative electrode, current concentrates around the electrode tabs on the electrode surfaces, making it easy for metals such as lithium to deposit. Furthermore, if metal deposits on the electrode surfaces of secondary batteries, capacity may decrease or electrodes may short-circuit, so there is a need to suppress such metal deposition on the electrode surfaces.

[0007] However, the above-mentioned conventional secondary batteries have room for improvement in terms of suppressing metal deposition on the electrode surfaces during charging.

[0008] Therefore, an object of the present invention is to provide a secondary battery in which metal deposition on the electrode surface during charging is suppressed. [Means for solving the problem]

[0009] The present inventors conducted extensive research to achieve the above object, and discovered that metal deposition on the electrode surface during charging of a secondary battery can be suppressed by increasing the resistance A per unit area of ​​a rectangular region P, which has a pair of opposite sides formed by a connection edge of either the positive electrode tab or the negative electrode tab and a line segment located a predetermined distance from the connection edge, in a surface Z that is at least one of the bonding surface X between the positive electrode and the separator and the bonding surface Y between the negative electrode and the separator, compared with the resistance B per unit area of ​​a region Q other than the region P, and thus completed the present invention.

[0010] That is, the present invention has an object to advantageously solve the above-mentioned problems, and the secondary battery of the present invention is a secondary battery having a laminate formed by stacking a positive electrode, a separator, and a negative electrode in this order, wherein when at least one of a bonding surface X between the positive electrode and the separator and a bonding surface Y between the negative electrode and the separator is defined as surface Z, and the length of a connection edge of either a positive electrode tab connected to the positive electrode or a negative electrode tab connected to the negative electrode is defined as L, the resistance A per unit area of ​​a rectangular region P of surface Z, whose pair of opposite sides is the connection edge and a line segment distanced 0.3L from the connection edge, is greater than the resistance B per unit area of ​​a region Q other than region P. In this way, by making the resistance A per unit area of ​​a rectangular region P (hereinafter sometimes referred to as the "electrode tab peripheral region P") of the surface Z, whose pair of opposite sides is the connection edge of either the positive electrode tab or the negative electrode tab and a line segment located the predetermined distance from the connection edge, larger than the resistance B per unit area of ​​a region Q other than region P (hereinafter sometimes referred to as the "other region Q"), it is possible to suppress metal deposition on the electrode surface when the secondary battery is being charged. In the present invention, the resistance A per unit area of ​​the predetermined electrode tab peripheral region P and the resistance B per unit area of ​​the other region Q can be measured by the method described in the examples of this specification.

[0011] Here, in the secondary battery of the present invention, it is preferable that the coverage rate E of the adhesive material in the region P of the surface Z is greater than the coverage rate F of the adhesive material in the region Q. If the coverage rate E of the adhesive material in the electrode tab peripheral region P is greater than the coverage rate F of the adhesive material in the other region Q, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed.

[0012] Furthermore, in the secondary battery of the present invention, the coverage rate E is preferably 1.3% or more and 30% or less. If the coverage rate E of the adhesive material in the electrode tab peripheral region P of surface Z is within the above-mentioned range, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed. Furthermore, if the coverage rate E of the adhesive material in the electrode tab peripheral region P of surface Z is within the above-mentioned range, the adhesive strength between the electrode and the separator can be sufficiently ensured, and the secondary battery can exhibit sufficiently excellent output characteristics.

[0013] In the secondary battery of the present invention, the coverage F is preferably 0.5% or more and less than 0.4×E%. If the coverage F of the adhesive material in the other region Q of the surface Z is within the above-mentioned range, the adhesive strength between the electrode and the separator can be sufficiently ensured, and the secondary battery can exhibit sufficiently excellent output characteristics.

[0014] In addition, in the secondary battery of the present invention, it is preferable that an adhesive material is present on the surface Z, the adhesive material contains a particulate polymer, and the particulate polymer has a core-shell structure including a core portion and a shell portion partially covering the outer surface of the core portion. By using a particulate polymer having a core-shell structure including a core portion and a shell portion partially covering the outer surface of the core portion as the adhesive material, it is possible to ensure sufficient adhesive strength between the electrode and the separator and to enable the secondary battery to exhibit sufficiently excellent output characteristics.

[0015] Furthermore, the present invention has an object to advantageously solve the above-mentioned problems, and provides a method for manufacturing a secondary battery having a laminate formed by stacking a positive electrode, a separator, and a negative electrode in this order, the method including a step of applying an adhesive material to a surface Z, which is at least one of a bonding surface X between the positive electrode and the separator and a bonding surface Y between the negative electrode and the separator, wherein, when the length of a connecting edge of either the positive electrode tab connected to the positive electrode or the negative electrode tab connected to the negative electrode is L, a coverage rate E of the adhesive material in a rectangular region P of the surface Z, whose pair of opposite sides is the connecting edge and a line segment 0.3L away from the connecting edge, is greater than a coverage rate F of the adhesive material in a region Q other than the region P. Thus, the above-described method for manufacturing a secondary battery of the present invention can provide a secondary battery in which metal deposition on the electrode surfaces during charging is suppressed.

[0016] Here, in the method for manufacturing a secondary battery of the present invention, the coverage rate E is preferably 1.3% or more and 30% or less. If the coverage rate E of the adhesive material in the electrode tab peripheral region P of surface Z is within the above-mentioned predetermined range, metal deposition on the electrode surface during charging of the manufactured secondary battery can be further suppressed. Furthermore, if the coverage rate E of the adhesive material in the electrode tab peripheral region P of surface Z is within the above-mentioned predetermined range, the adhesive strength between the electrode and the separator can be sufficiently ensured, and the manufactured secondary battery can exhibit sufficiently excellent output characteristics.

[0017] In addition, in the method for producing a secondary battery of the present invention, the coverage F is preferably 0.5% or more and less than 0.4×E%. If the coverage F of the adhesive material in the other region Q of the surface Z is within the above-mentioned range, the adhesive strength between the electrode and the separator can be sufficiently ensured, and the produced secondary battery can exhibit sufficiently excellent output characteristics.

[0018] In addition, the method for producing a secondary battery of the present invention is characterized in that the adhesive material contains a particulate polymer, and the particulate polymer has a core-shell structure including a core portion and a shell portion partially covering the outer surface of the core portion. By using a particulate polymer having a core-shell structure including a core portion and a shell portion partially covering the outer surface of the core portion as the adhesive material, it is possible to ensure sufficient adhesive strength between the electrode and the separator, and to enable the produced secondary battery to exhibit sufficiently excellent output characteristics. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a secondary battery in which metal deposition on the electrode surface during charging is suppressed. [Brief explanation of the drawings]

[0020] [Figure 1] 1(a) is a front view showing an example of the structure of a laminate in a secondary battery of the present invention, and FIG. 1(b) is a plan view illustrating the positional relationship between the negative electrode and the positive electrode of the laminate shown in FIG. 1(a). [Figure 2] 1 is a front view showing the structure of an example of a stack obtained by stacking stacks in a secondary battery of the present invention. FIG. [Figure 3] FIG. 10 is a front view showing the structure of another example of the laminate in the secondary battery of the present invention. [Figure 4] 10 is an explanatory diagram illustrating an electrode tab peripheral region P on a plane Z. FIG. [Figure 5] 10 is an explanatory diagram showing an example of a method for applying an adhesive material to a surface Z. FIG. [Figure 6] 10 is an explanatory diagram showing another example of a method for applying an adhesive material to a surface Z. FIG. [Figure 7] FIG. 2 is an explanatory diagram showing an example of a coating pattern of an adhesive material. [Figure 8] FIG. 10 is an explanatory diagram showing another example of a coating pattern of an adhesive material. [Figure 9] FIG. 1 is a cross-sectional view schematically illustrating the structure of an example of a particulate polymer. [Figure 10] 3A to 3C are explanatory views showing an example of a manufacturing process of a laminate in the secondary battery of the present invention. [Figure 11] FIG. 11 is an explanatory diagram showing an example of a coating machine (nozzle head) in FIG. [Figure 12] 1A to 1C are explanatory views showing the manufacturing process of the laminate in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0021] The secondary battery and the method for manufacturing the secondary battery of the present invention will be described below with reference to the drawings. Note that in each drawing, the dimensions of some components are enlarged or reduced to facilitate understanding.

[0022] (Secondary battery) The secondary battery of the present invention includes at least a predetermined laminate, and optionally includes an electrolyte solution and other components. The secondary battery of the present invention can be manufactured using, for example, the method for manufacturing a secondary battery of the present invention.

[0023] <Laminate> The laminate in the secondary battery of the present invention has a laminate formed by laminating a positive electrode, a separator, and a negative electrode in this order. Here, the laminate in the secondary battery of the present invention has, for example, a structure as shown in Fig. 1 or a structure as shown in Fig. 3. The laminates are stacked to form a laminate 200 as shown in Fig. 2, for example, and can be used in a stacked secondary battery or the like. As shown in FIG. 1 or 3, the laminate 100, 100A includes a negative electrode 20, a first separator 10 bonded to one surface of the negative electrode, a positive electrode 40 bonded to the surface of the first separator 10 opposite to the negative electrode 20 side, and a second separator 30 bonded to the other surface of the negative electrode 20 or the surface of the positive electrode 40 opposite to the first separator side 10. 1(b), in the laminates 100, 100A, the size of the positive electrode 40 in a plan view is smaller than the sizes of the negative electrode 20, the first separator 10, and the second separator 30 in a plan view. Specifically, in a plan view, the negative electrode 20 of the laminates 100, 100A has a first edge 24 and a second edge 25 that face each other in a direction perpendicular to the stacking direction, and when viewed in the stacking direction, the positive electrode 40 is located between the first edge 24 and the second edge 25. Note that the first edge 24 and the second edge 25 are typically edges that correspond to the cutting positions when a long negative electrode blank is cut to obtain the negative electrode 20.

[0024] Here, the laminate 100 shown in a front view in FIG. 1(a) includes a negative electrode 20, a first separator 10 bonded to one surface of the negative electrode 20 (the upper surface in FIG. 1), a positive electrode 40 bonded to the surface of the first separator 10 opposite to the negative electrode 20 (the upper surface in FIG. 1), and a second separator 30 bonded to the other surface of the negative electrode 20. In this example, the first separator 10, the negative electrode 20, the second separator 30, and the positive electrode 40 are rectangular in plan view. The negative electrode 20 has a structure in which negative electrode composite layers 22 and 23 containing a negative electrode active material are formed on both surfaces of a negative electrode current collector 21, and the positive electrode 40 has a structure in which positive electrode composite layers 42 and 43 containing a positive electrode active material are formed on both surfaces of a positive electrode current collector 41. Furthermore, the size of the positive electrode 40 in plan view is smaller than the sizes of the negative electrode 20, the first separator 10, and the second separator 30. As shown in Figure 1(b) which shows the positional relationship between the negative electrode 20 and the positive electrode 40 in plan view, the positive electrode 40 is located between a first edge 24 and a second edge 25 of the negative electrode 20 which face each other in a direction perpendicular to the stacking direction (the left-right direction in Figure 1(b)), and between a third edge 26 and a fourth edge 27 which are perpendicular to the first edge 24 and the second edge 25 and extend in the left-right direction in Figure 1(b).

[0025] 3 shows a front view of the laminate 100A, which has the same configuration as the laminate 100 shown in FIG. 1, except that the second separator 30 is bonded to the surface of the positive electrode 40 opposite to the first separator 10 side (the upper side in FIG. 3) instead of to the other surface of the negative electrode 20.

[0026] The laminate in the secondary battery of the present invention is not limited to the examples shown in Figures 1 and 3. For example, in the laminate, the size of the first separator 10 and the second separator 30 in a plan view may be larger than the size of the negative electrode 20. Use of a laminate in which the first separator 10 and the second separator 30 are larger than the negative electrode 20 can further improve the safety of the secondary battery.

[0027] <<Surface Z, electrode tabs (positive electrode tab, negative electrode tab), electrode tab surrounding area P>> Surface Z is at least one of the bonding surface X between the negative electrode and the separator and the bonding surface Y between the positive electrode and the separator. A positive electrode tab is connected to the positive electrode, and a positive electrode tab is connected to the negative electrode. Furthermore, the length of the connection side of either the positive electrode tab connected to the positive electrode or the negative electrode tab connected to the negative electrode is defined as L. The electrode tab peripheral region P is a rectangular region of the surface Z, with a pair of opposite sides being the connecting edge of either the positive electrode tab or the negative electrode tab and a line segment that is 0.3L away from the connecting edge.

[0028] Here, the electrode tab peripheral region P on the plane Z will be described more specifically with reference to FIG. In FIG. 4, surface Z is at least one of surface X where the negative electrode 20 and the first separator 10 are attached and surface Y where the positive electrode 40 and the first separator 10 are attached. A positive electrode tab 44 is connected to the positive electrode 40, and the length of the connection side of the positive electrode tab 44 is L1. A negative electrode tab 28 is connected to the negative electrode 20, and the length of the connection side of the negative electrode tab 28 is L2.

[0029] The electrode tab peripheral region P is either (1) a rectangular region P1 (positive electrode tab peripheral region P1) having a pair of opposite sides formed by the connection side of the positive electrode tab 44 and a line segment that is 0.3L1 away from the connection side of the positive electrode tab 44, or (2) a rectangular region P2 (negative electrode tab peripheral region P2) having a pair of opposite sides formed by the connection side of the negative electrode tab 28 and a line segment that is 0.3L2 away from the connection side of the negative electrode tab 28.

[0030] The electrode tab peripheral region P refers to the region on the periphery or inside of the above-mentioned rectangle on the surface Z. Therefore, if a part of the above-mentioned rectangle is located outside the periphery of the surface Z, the electrode tab peripheral region refers to only the region that is on the periphery or inside of the rectangle and that is also on the periphery or inside of the surface Z.

[0031] Here, the ratio of the area of ​​the positive electrode tab peripheral region P1 alone to the area of ​​the entire surface Z is preferably 2.5% or more, more preferably 2.7% or more, even more preferably 3% or more, and preferably 10% or less. If the ratio of the area of ​​the positive electrode tab peripheral region P1 alone to the area of ​​the entire surface Z is equal to or greater than the above lower limit, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed. On the other hand, if the ratio of the area of ​​the positive electrode tab peripheral region P1 alone to the area of ​​the entire surface Z is equal to or less than the above upper limit, the output characteristics of the secondary battery can be improved. Furthermore, the ratio of the area of ​​the negative electrode tab peripheral region P2 alone to the area of ​​the entire surface Z can be set within the same range as the range of the area of ​​the positive electrode tab peripheral region P1 alone to the area of ​​the entire surface Z described above. Furthermore, the ratio of the total area of ​​the positive electrode tab peripheral region P1 and the negative electrode tab peripheral region P2 to the total area of ​​surface Z is preferably 5% or more, more preferably 5.4% or more, even more preferably 6% or more, and preferably 20% or less. If the ratio of the total area of ​​the positive electrode tab peripheral region P1 and the negative electrode tab peripheral region P2 to the total area of ​​surface Z is equal to or greater than the above-mentioned lower limit, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed. On the other hand, if the ratio of the total area of ​​the positive electrode tab peripheral region P1 and the negative electrode tab peripheral region P2 to the total area of ​​surface Z is equal to or less than the above-mentioned upper limit, the output characteristics of the secondary battery can be improved. The length of the connection side of the positive electrode tab 44 and / or the negative electrode tab 28 and the area of ​​the surface Z can be adjusted as appropriate so that the area of ​​the positive electrode tab peripheral region P1 and / or the negative electrode tab peripheral region P2 satisfies the above-mentioned specified conditions.

[0032] Here, the electrode tab, which is either the positive electrode tab 44 or the negative electrode tab 28, is not particularly limited, but is usually connected to the periphery of the electrode as shown in FIG.

[0033] In this specification, the "connection edge" of an electrode tab connected to an electrode refers to the boundary line between the electrode and the electrode tab observed when the electrode is viewed in plan view. That is, when the electrode tab is connected to the periphery of the electrode, the connection edge of the electrode tab refers to the line segment connecting both end points of the portion of the periphery of the electrode to which the electrode tab is connected, and when the electrode tab is connected inside the periphery of the electrode, the connection edge of the electrode refers to the line segment connecting both end points of the portion of the periphery of the electrode that intersects with the electrode tab.

[0034] The material constituting the electrode tabs is not particularly limited as long as the secondary battery operates normally. For example, the material constituting the current collector of each electrode can be used, such as aluminum constituting the positive electrode current collector for the positive electrode tab, or copper constituting the negative electrode current collector for the negative electrode tab.

[0035] Furthermore, the method for forming an electrode tab on an electrode is not particularly limited, and for example, the electrode tab can be formed by making the material constituting the current collector of the electrode protrude from the periphery of the electrode. More specifically, when forming an electrode mixture layer on the current collector during electrode manufacturing, a region where the electrode mixture layer is not formed is provided at the end of the current collector, and the region can be later cut into a desired shape, thereby forming the electrode tab.

[0036] 4, the arrangement of the positive electrode tab 44 and the negative electrode tab 28 when the surface Z is viewed from above may be such that the positive electrode tab 44 and the negative electrode tab 28 are arranged on the same edge side of the rectangular surface Z, but is not limited thereto, and the positive electrode tab 44 and the negative electrode tab 28 may be arranged on different edge sides of the surface Z. For example, of the two opposing edges of the rectangular surface Z, the positive electrode tab 44 may be arranged on one edge side, and the negative electrode tab 28 may be arranged on the other edge side. In FIG. 4, the positive electrode 40, the negative electrode 20, and the first separator 10 are all the same size, and therefore the bonding surface X between the negative electrode 20 and the first separator 10 and the bonding surface Y between the positive electrode 40 and the first separator 10 coincide with each other. Therefore, the connection edge of the positive electrode tab on the periphery of the bonding surface X and the connection edge of the negative electrode tab on the periphery of the bonding surface Y are located on the periphery of a single surface Z in plan view; however, the laminate in the secondary battery of the present invention is not limited to this.

[0037] The secondary battery of the present invention is characterized in that the resistance A per unit area of ​​the electrode tab peripheral region P is greater than the resistance B per unit area of ​​the region Q (other region Q) on the surface Z other than the electrode tab peripheral region P. In this way, by making the resistance A per unit area of ​​the electrode tab peripheral region P greater than the resistance B of the region Q on the surface Z other than the electrode tab peripheral region P, it is possible to suppress metal deposition on the electrode surface when the secondary battery is being charged.

[0038] The secondary battery of the present invention only needs to satisfy at least one of the following conditions: (i) the resistance per unit area A1 of the positive electrode tab peripheral region P1 is greater than the resistance per unit area B1 of the other region Q1 on the surface Z other than the positive electrode tab peripheral region P1, or (ii) the resistance per unit area A2 of the negative electrode tab peripheral region P2 is greater than the resistance per unit area B2 of the other region Q2 on the surface Z other than the negative electrode tab peripheral region P2. From the viewpoint of further suppressing metal deposition on the electrode surface during charging of the secondary battery, it is preferable that the secondary battery of the present invention satisfies both of the above conditions (i) and (ii).

[0039] Here, the reason why metal deposition on the electrode surface during charging of the secondary battery can be suppressed by making the resistance A per unit area of ​​the electrode tab peripheral region P larger than the resistance B per unit area of ​​the other region Q is not clear, but is presumed to be as follows. First, in a secondary battery, current flows through surface Z during charging, and metals such as lithium are likely to deposit in areas of surface Z where the current density is high. In conventional secondary batteries, particularly large batteries for automotive applications, in which the resistance A of the electrode tab peripheral region P is equal to or less than the resistance B of the secondary battery, the electrode tab peripheral region P is close to the electrode tab that handles the input and output of power, and therefore the current density is high, making it easier for metals to deposit. In contrast, in the secondary battery of the present invention, the resistance A per unit area in the electrode tab peripheral region P is made larger than the resistance B per unit area in the other region Q, thereby making it possible to uniformize the current density throughout the secondary battery during charging. This is thought to reduce the deposition of metals such as lithium in the electrode tab peripheral region P. Therefore, it is presumed that metal deposition on the electrode surface can be suppressed during charging of the secondary battery.

[0040] The ratio (A / B) of the resistance per unit area A of the electrode tab peripheral region P to the resistance per unit area B of the other region Q must be greater than 1, preferably greater than 1.005, more preferably greater than 1.01, and preferably less than 2, more preferably less than 1.5. When the ratio (A / B) of the resistance per unit area A of the electrode tab peripheral region P to the resistance per unit area B of the other region Q is greater than 1, metal deposition on the electrode surface during charging of the secondary battery can be sufficiently suppressed. On the other hand, when the ratio (A / B) of the resistance per unit area A of the electrode tab peripheral region P to the resistance per unit area B of the other region Q is less than 2, the output characteristics of the secondary battery can be improved. The resistance A per unit area of ​​the electrode tab peripheral region P and the resistance B per unit area of ​​the other region Q can be adjusted by adjusting the coverage of the adhesive material in each region, the type of polymer used as the adhesive material, etc.

[0041] [Adhesive material] Here, an adhesive material is usually present on the surface Z (the bonding surfaces X and Y). The adhesive material is a material that bonds the electrode (positive electrode or negative electrode) and the separator on the bonding surfaces X and Y. Details of the adhesive material will be described later.

[0042] -How to apply adhesive materials- The adhesive material can be supplied to the bonding surfaces X and Y in any state, such as a solid state, a molten state, a state dissolved in a solvent, or a state dispersed in a solvent. Among these, the adhesive material is preferably supplied in a state dissolved in a solvent or a state dispersed in a solvent, and more preferably supplied in a state dispersed in a solvent.

[0043] When the adhesive material is supplied to the bonding surfaces X and Y in a state where it is dissolved or dispersed in a solvent, i.e., when an adhesive composition containing an adhesive material and a solvent is supplied to the bonding surfaces, the solvent for the adhesive composition is not particularly limited and can be, for example, water, an organic solvent, or a mixture thereof. The organic solvent is not particularly limited and can include, for example, cyclic aliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; ketones such as ethyl methyl ketone and cyclohexanone; esters such as ethyl acetate, butyl acetate, γ-butyrolactone, and ε-caprolactone; nitriles such as acetonitrile and propionitrile; ethers such as tetrahydrofuran and ethylene glycol diethyl ether; and alcohols such as methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, and ethylene glycol monomethyl ether. Among the above, from the viewpoint of efficiently producing a laminate, the solvent is preferably a solvent containing at least one of water and alcohol. At least a part of the solvent may be removed by drying or the like in the process of producing the laminate.

[0044] The application of the adhesive material using the coater (51 to 54 in Figs. 10 and 11) described below can be carried out using known coating methods such as the inkjet method, spray method, dispenser method, gravure coating method, screen printing method, etc. Among these, it is preferable to apply the adhesive material using the inkjet method, from the viewpoint of easily adjusting the amount and range of the adhesive material to be applied.

[0045] The adhesive material is applied only to a portion of the bonding surfaces X and Y. Specifically, the adhesive material is arranged (applied) on the bonding surfaces X and Y in a predetermined pattern, such as a stripe pattern, a dot pattern, or a grid pattern. From the viewpoint of improving the output characteristics of the secondary battery, the adhesive material is preferably arranged (applied) on the bonding surfaces X and Y in a dot pattern.

[0046] Here, the diameter of the adhesive dots arranged in the dot pattern is preferably 10 μm or more, more preferably 20 μm or more, and preferably 100 μm or less, more preferably 80 μm or less. If the diameter of the adhesive dots is equal to or greater than the above-mentioned lower limit, the adhesive strength between the electrode and the separator can be increased. On the other hand, if the diameter of the adhesive dots is equal to or less than the above-mentioned upper limit, a decrease in the output characteristics of the secondary battery can be suppressed.

[0047] Hereinafter, a case will be described in which adhesive material is applied to a surface Z so that two areas exist: an area S where the adhesive material is densely applied and an area T where the adhesive material is sparsely applied. Here, the coverage rate of the adhesive material in the "region S where the adhesive material is densely applied" is assumed to be greater than the coverage rate of the adhesive material in the "region T where the adhesive material is sparsely applied". In this specification, the "coverage rate of adhesive material" of a certain surface or region refers to the ratio of the area of ​​the portion covered with adhesive material to the total area of ​​the surface or region [(area of ​​the portion covered with adhesive material / total area of ​​the surface or region) x 100 (%)]. Furthermore, in this specification, when an adhesive composition containing an adhesive material and a solvent is supplied to a bonding surface, the "adhesive material" in the "coverage rate of adhesive material" refers to the adhesive layer composition in a state in which the solvent has been removed by drying or the like.

[0048] The shape of the "region S where the adhesive material is densely applied" is not particularly limited and can be set appropriately within a range in which the desired effects of the present invention can be obtained. That is, the "region S where the adhesive material is densely applied" can have any shape as long as the resistance A of the electrode tab peripheral region P described above is greater than the resistance B of the secondary battery. Furthermore, multiple regions located apart from each other within the plane Z may be combined into one "region S where the adhesive material is densely applied." The "region T where the adhesive material is sparsely applied" is the entire region of the surface Z other than the "region S where the adhesive material is densely applied."

[0049] From the viewpoint of further suppressing metal deposition on the electrode surface when the secondary battery is being charged, it is preferable to set the shape of the "area S where the adhesive material is densely applied" so that the coverage rate E of the adhesive material in the above-mentioned electrode tab peripheral area P is greater than the coverage rate F of the adhesive material in the other area Q.

[0050] The area S where the adhesive material is densely applied preferably includes at least a part of the electrode tab peripheral area P (the positive electrode tab peripheral area P1 and / or the periphery of the negative electrode tab), and more preferably includes the entire electrode tab peripheral area P (the positive electrode tab peripheral area P1 and / or the negative electrode tab peripheral area P2).

[0051] For example, as shown in Fig. 5, when the positive electrode tab 44 and the negative electrode tab 28 are arranged on the same edge side of the rectangular surface Z, the region S where the adhesive material is densely applied can be the region between the edge on which the positive electrode tab 44 and the negative electrode tab 28 are arranged and a straight line parallel to that edge. In Fig. 5, the region S where the adhesive material is densely applied includes the entire positive electrode tab peripheral region P1 and the entire negative electrode tab peripheral region P2 described above.

[0052] 6, for example, when the positive electrode tab 44 is arranged on one of two opposing edges of the rectangular surface Z and the negative electrode tab 28 is arranged on the other edge, the region S where the adhesive material is densely applied can be a belt-shaped region connecting the connection side of the positive electrode tab 44 and the connection side of the negative electrode tab 28. In FIG. 6, the region S where the adhesive material is densely applied includes the entire positive electrode tab peripheral region P1 and the entire negative electrode tab peripheral region P2 described above.

[0053] 5 and 6, a case where the adhesive material is applied to the surface Z when the positive electrode tabs and negative electrode tabs are arranged, i.e., when each electrode tab is connected to each electrode, is described in detail. However, the manufacturing of the laminate in the secondary battery of the present invention is not limited to this, and the adhesive material may be applied to the surface Z when each electrode tab is not connected to each electrode. Even when the adhesive material is applied to the surface Z when each electrode tab is not connected to each electrode, the above-mentioned electrode tab peripheral region P can be set based on the predetermined arrangement of the positive electrode tabs and negative electrode tabs, and the adhesive material can be applied to the surface Z preferably so that the coverage rate E of the adhesive material in the electrode tab peripheral region P is greater than the coverage rate F of the adhesive material in the other regions Q, within a range in which the desired effects of the present invention can be obtained.

[0054] The ratio of the area of ​​the "region S where the adhesive material is densely applied" to the entire area of ​​surface Z is preferably 5% or more, more preferably 10% or more, and preferably 60% or less, more preferably 40% or less, and even more preferably 30% or less. If the ratio of the area of ​​the "region S where the adhesive material is densely applied" to the entire area of ​​surface Z is within the above-mentioned specified range, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed. Furthermore, if the ratio of the area of ​​the "region S where the adhesive material is densely applied" to the entire area of ​​surface Z is equal to or less than the above-mentioned upper limit, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0055] Furthermore, the ratio of the area of ​​the "region T where the adhesive material is sparsely applied" to the entire area of ​​surface Z is preferably 40% or more, more preferably 60% or more, even more preferably 70% or more, and preferably 95% or less, and more preferably 90% or less. If the ratio of the area of ​​the "region T where the adhesive material is sparsely applied" to the entire area of ​​surface Z is within the above-mentioned specified range, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed. Furthermore, if the ratio of the area of ​​the "region T where the adhesive material is sparsely applied" to the entire area of ​​surface Z is equal to or greater than the above-mentioned lower limit, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0056] The coverage rate J of the adhesive material in the "region S where the adhesive material is densely applied" is not particularly limited as long as it is greater than the coverage rate K of the adhesive material in the "region T where the adhesive material is sparsely applied", but is preferably 1.1% or more, more preferably 3% or more, preferably 30% or less, more preferably 10% or less, and even more preferably 8% or less. If the coverage rate J of the adhesive material in the "region S where the adhesive material is densely applied" is equal to or greater than the above lower limit, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed. Furthermore, if the coverage rate J of the adhesive material in the "region S where the adhesive material is densely applied" is equal to or less than the above upper limit, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0057] Furthermore, the coverage rate K of the adhesive material in the "region T where the adhesive material is sparsely applied" is not particularly limited as long as it is smaller than the coverage rate J of the adhesive material in the "region S where the adhesive material is densely applied", but is preferably 0.3% or more, more preferably 0.5% or more, and preferably less than 0.4 × J%. If the coverage rate K of the adhesive material in the "region T where the adhesive material is sparsely applied" is equal to or greater than the above lower limit, sufficient adhesion between the electrode and the separator can be ensured. Furthermore, if the coverage rate K of the adhesive material in the "region T where the adhesive material is sparsely applied" is less than the above upper limit, metal deposition on the electrode surface during charging of the secondary battery can be sufficiently suppressed.

[0058] The coverage rate of the adhesive material in each of the "area S where the adhesive material is densely applied" and the "area T where the adhesive material is sparsely applied" can be adjusted by changing the arrangement pattern of the adhesive material arranged (applied) in each of the areas.

[0059] Specifically, when adhesive material is arranged (applied) in a dotted pattern in a certain area, the coverage rate of the adhesive material in that area can be adjusted by changing the radius and center-to-center distance of the adhesive material dots. For example, in an area where the adhesive material is arranged (applied) in a dot pattern in which dots are formed at regular intervals in two orthogonal directions as shown in FIG. 7, the coverage of the adhesive material can be calculated using the center-to-center distances (pitch) x and y of the dots and the radius r of the dots according to the following formula (1). Adhesive material coverage = {πr 2 / (x·y)}×100(%) (1)

[0060] Furthermore, when adhesive material is arranged (coated) in a striped pattern in a certain area, the coverage rate of the adhesive material in that area can be adjusted by changing the line width of the coated areas of the adhesive material and the spacing between the coated areas (line width of the uncoated areas). For example, in an area where the adhesive material is coated in a striped pattern as shown in Figure 8, where the line width of the coated portion of the adhesive material is 1 and the spacing between the coated portions (the line width of the uncoated portions) is s, the coverage rate of the adhesive material can be calculated using the following formula (2). Coverage rate of adhesive material = {l / (l+s)} × 100(%) (2)

[0061] The adhesive material weight in the area S where the adhesive material is densely applied is 0.02 g / m 2 It is preferable that the content is 0.8 g / m or more. 2 Preferably, it is 0.35 g / m or less. 2It is more preferable that the adhesive material be applied in a densely coated region S with a basis weight of at least the above lower limit. If the adhesive material is applied in a densely coated region S with a basis weight of at least the above upper limit, the adhesive strength between the electrode and the separator can be sufficiently ensured. Furthermore, if the adhesive material is applied in a densely coated region S with a basis weight of at most the above upper limit, the secondary battery can have sufficiently high output characteristics.

[0062] Furthermore, the basis weight of the adhesive material in the region T where the adhesive material is sparsely applied is 0.02 g / m 2 It is preferable that the content is 0.03 g / m or more. 2 More preferably, it is 0.35 g / m or more. 2 It is preferable that the adhesive material be applied in a sparsely applied region T with a basis weight of the adhesive material equal to or greater than the lower limit. If the adhesive material is applied in a sparsely applied region T with a basis weight of the adhesive material equal to or less than the upper limit, the adhesive strength between the electrode and the separator can be sufficiently ensured. Furthermore, if the adhesive material is applied in a sparsely applied region T with a basis weight of the adhesive material equal to or less than the upper limit, the output characteristics of the secondary battery can be sufficiently high. In this specification, when an adhesive composition containing an adhesive material and a solvent is supplied to a bonding surface, the "adhesive material" in the "basis weight of adhesive material" refers to the adhesive layer composition in a state in which the solvent has been removed by drying or the like.

[0063] In each of the above-mentioned "area S where adhesive material is densely applied" and "area T where adhesive material is sparsely applied," the adhesive material may be arranged (applied) in the same pattern throughout, or adhesive material arranged (applied) in multiple different patterns may be mixed.

[0064] In each region, the pattern in which the adhesive material is applied may gradually change along a certain direction. For example, if the adhesive material is applied in a dotted pattern, the radius and center-to-center distance of the adhesive dots may gradually change along a certain direction, and if the adhesive material is applied in a striped pattern, the line width of the coated portion of the adhesive material and the spacing between the coated portions (line width of the uncoated portion) may gradually change along a certain direction.

[0065] The electrode tab peripheral region P may or may not coincide with the "region S where the adhesive material is densely applied." Therefore, the electrode tab peripheral region P may contain only a portion corresponding to the "region S where the adhesive material is densely applied," or may contain a mixture of a portion corresponding to the "region S where the adhesive material is densely applied" and a portion corresponding to the "region S where the adhesive material is sparsely applied." Furthermore, the other regions Q may or may not coincide with the "region T where the adhesive material is sparsely applied." Therefore, the other regions Q may only include a portion corresponding to the "region T where the adhesive material is sparsely applied," or may include a mixture of a portion corresponding to the "region S where the adhesive material is densely applied" and a portion corresponding to the "region T where the adhesive material is sparsely applied."

[0066] Here, when a region U, which is either the electrode tab peripheral region P or another region Q, contains a mixture of a portion corresponding to the "region S where the adhesive material is densely applied" and a portion corresponding to the "region T where the adhesive material is sparsely applied," the coverage rate of the adhesive material in the region U can be calculated using the following formula (3). Coverage of adhesive material in region U = (coverage of adhesive material in region S) × (ratio of area of ​​region S to the total area of ​​region U) + (coverage of adhesive material in region T) × (ratio of area of ​​region T to the total area of ​​region U) (3)

[0067] The coverage rate E of the adhesive material in the electrode tab peripheral region P is preferably greater than the coverage rate F of the adhesive material in the other region Q. Specifically, the coverage rate E of the adhesive material in the electrode tab peripheral region P is preferably 1.1% or more, more preferably 1.4% or more, even more preferably 3% or more, and preferably 30% or less, more preferably 10% or less, and even more preferably 8% or less. If the coverage rate E of the adhesive material in the electrode tab peripheral region P is equal to or greater than the above-mentioned lower limit, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed. On the other hand, if the coverage rate E of the adhesive material in the electrode tab peripheral region P is equal to or less than the above-mentioned upper limit, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0068] Furthermore, it is preferable that the coverage rate F of the adhesive material in the other region Q is smaller than the coverage rate E of the adhesive material in the peripheral region P of the electrode tab. Specifically, the coverage F of the adhesive material in the other region Q is preferably 0.5% or more, more preferably 0.7% or more, and preferably less than 0.4×E%. If the coverage F of the adhesive material in the other region Q is equal to or greater than the lower limit, sufficient adhesive strength between the electrode and the separator can be ensured. On the other hand, if the coverage F of the adhesive material in the other region Q is less than the upper limit, sufficiently high output characteristics of the secondary battery can be ensured.

[0069] Furthermore, the ratio (E / F) of the coverage rate E of the adhesive material in the electrode tab peripheral region P to the coverage rate F of the adhesive material in the other regions Q is preferably 1.5 or more, more preferably 1.8 or more, even more preferably 2.5 or more, and is preferably 9.0 or less, and more preferably 5.0 or less. If the ratio (E / F) of the coverage rate E of the adhesive material in the electrode tab peripheral region P to the coverage rate F of the adhesive material in the other regions Q is equal to or greater than the above lower limit, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed. On the other hand, if the ratio (E / F) of the coverage rate E of the adhesive material in the electrode tab peripheral region P to the coverage rate F of the adhesive material in the other regions Q is equal to or less than the above upper limit, both the adhesive strength between the electrode and separator and the output characteristics of the secondary battery can be achieved at high levels.

[0070] It is preferable that the secondary battery of the present invention satisfies at least one of the following conditions: (i) the coverage rate E1 in the positive electrode tab peripheral region P1 is greater than the coverage rate F1 in the other region Q1 on the surface Z other than the positive electrode tab peripheral region P1; or (ii) the coverage rate E2 in the negative electrode tab peripheral region P2 is greater than the coverage rate F2 in the other region Q2 on the surface Z other than the negative electrode tab peripheral region P2. From the viewpoint of further suppressing metal deposition on the electrode surface during charging of the secondary battery, it is more preferable that the secondary battery satisfies both of the above-mentioned conditions (i) and (ii).

[0071] The weight of the adhesive material in the electrode tab peripheral region P is 0.02 g / m 2 It is preferable that the content is 0.8 g / m or more. 2 Preferably, it is 0.35 g / m or less. 2 It is more preferable that the adhesive weight in the central region P is equal to or greater than the above lower limit, the adhesive strength between the electrode and the separator can be sufficiently ensured. Furthermore, if the adhesive weight in the central region P is equal to or less than the above upper limit, the output characteristics of the secondary battery can be sufficiently high.

[0072] Furthermore, the basis weight of the adhesive material in the other region Q is 0.02 g / m 2 It is preferable that the content is 0.03 g / m or more. 2 More preferably, it is 0.35 g / m or more. 2 It is preferable that the weight per unit area of ​​the adhesive material in the other region Q is equal to or greater than the above lower limit, the adhesive strength between the electrode and the separator can be sufficiently ensured. Also, if the weight per unit area of ​​the adhesive material in the other region Q is equal to or less than the above upper limit, the output characteristics of the secondary battery can be sufficiently high.

[0073] -Details of adhesive materials- The adhesive material is not particularly limited as long as it does not inhibit the battery reaction, and any adhesive material used in the field of secondary batteries can be used. Among these, it is preferable to use an adhesive material made of a polymer. The adhesive material may be made of one type of polymer, or two or more types of polymers.

[0074] Polymers that can be used as adhesive materials are not particularly limited, and examples thereof include fluorine-based polymers such as polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP); conjugated diene polymers such as styrene-butadiene copolymer (SBR) and acrylonitrile-butadiene copolymer (NBR); hydrogenated conjugated diene polymers; polymers containing (meth)acrylic acid alkyl ester monomer units (acrylic polymers); and polyvinyl alcohol polymers such as polyvinyl alcohol (PVA). In the present invention, the term "(meth)acrylic acid" means acrylic acid and / or methacrylic acid.

[0075] The shape of the adhesive material made of a polymer is not particularly limited, and may be particulate, non-particulate, or a combination of particulate and non-particulate. In addition, when the adhesive material made of a polymer is a particulate polymer, the particulate polymer adhesive material may be particles with a single phase structure formed from a single polymer, or particles with a heterogeneous phase structure formed by physically or chemically bonding two or more different polymers. Specific examples of heterophase structures include a core-shell structure in which the central part (core part) and the outer shell part (shell part) of spherical particles are formed from different polymers; and a side-by-side structure in which two or more polymers are arranged side by side. In the present invention, the "core-shell structure" includes not only a structure in which the shell portion completely covers the outer surface of the core portion, but also a structure in which the shell portion partially covers the outer surface of the core portion, as shown in Figure 9. In the present invention, even if the outer surface of the core part appears to be completely covered by the shell part, if pores communicating the inside and outside of the shell part are formed, the shell part is considered to be a shell part that partially covers the outer surface of the core part. Therefore, for example, a particulate polymer having a shell part with pores communicating from the outer surface of the shell part (i.e., the peripheral surface of the particulate polymer) to the outer surface of the core part corresponds to a particulate polymer in which the shell part partially covers the outer surface of the core part.

[0076] The swelling degree of the adhesive material in an electrolyte solution (a solution in which LiPF6 is dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate / diethyl carbonate = 3 / 7 by volume ratio) (hereinafter sometimes simply referred to as "swelling degree") is preferably 110% or more, and preferably 1500% or less, more preferably 1300% or less, and particularly preferably 1000% or less. If the swelling degree of the adhesive material is the above upper limit or less, the penetration of the electrolyte solution into the center of the positive electrode or negative electrode can be improved. The degree of swelling of the adhesive material with respect to the electrolyte solution can be measured by the method described in the examples of this specification.

[0077] --Particulate polymer-- It is preferable to use a particulate polymer as the adhesive material. As the particulate polymer, either a particulate polymer having a core-shell structure or a particulate polymer not having a core-shell structure may be used, but it is preferable to use at least a particulate polymer having a core-shell structure, and it is more preferable to use a particulate polymer having a core-shell structure and a particulate polymer not having a core-shell structure in combination. When a particulate polymer having a core-shell structure and a particulate polymer not having a core-shell structure are used in combination, the mass ratio of the particulate polymer having a core-shell structure to the particulate polymer not having a core-shell structure in the adhesive material can be appropriately adjusted within a range in which the desired effects of the present invention can be obtained.

[0078] =Particulate polymer having a core-shell structure= The particulate polymer having a core-shell structure is a component that functions as a binder in an adhesive material that bonds together battery components such as separators, electrodes, etc. By using the particulate polymer having a core-shell structure as a binder, it is possible to firmly bond together battery components via the adhesive material and also to enable the secondary battery to exhibit excellent output characteristics.

[0079] Here, the particulate polymer has a core-shell structure comprising a core portion and a shell portion covering the outer surface of the core portion. Here, the shell portion may cover the entire outer surface of the core portion, or may cover only a portion of the outer surface of the core portion. Even if the outer surface of the core portion appears to be completely covered by the shell portion from the outside, the shell portion is a shell portion that partially covers the outer surface of the core portion as long as holes that communicate between the inside and outside of the shell portion are formed.

[0080] The cross-sectional structure of an example of a particulate polymer is shown in Fig. 9. In Fig. 9, the particulate polymer 300 has a core-shell structure including a core portion 310 and a shell portion 320. Here, the core portion 310 is a portion of the particulate polymer 300 that is located more inward than the shell portion 320. The shell portion 320 is a portion that covers the outer surface 310S of the core portion 310, and is usually the outermost portion of the particulate polymer 300. In the example of Fig. 9, the shell portion 320 does not cover the entire outer surface 310S of the core portion 310, but only partially covers the outer surface 310S of the core portion 310.

[0081] The particulate polymer may have any constituent element other than the core and shell as described above, as long as the intended effect is not significantly impaired. Specifically, for example, the particulate polymer may have a portion formed of a polymer different from the core inside the core. As a specific example, seed particles used when producing the particulate polymer by seed polymerization may remain inside the core. However, from the viewpoint of significantly exhibiting the intended effect, it is preferable that the particulate polymer has only the core and shell.

[0082] The glass transition temperature of the polymer in the core portion of the particulate polymer is preferably -30°C or higher, more preferably -20°C or higher, and preferably 200°C or lower, more preferably 100°C or lower, and particularly preferably 50°C or lower. If the glass transition temperature of the polymer in the core portion is -30°C or higher, the battery components can be more firmly bonded to each other via the adhesive material. On the other hand, if the glass transition temperature of the polymer in the core portion is 200°C or lower, the polymerization stability of the particulate polymer can be ensured. The glass transition temperature of the core polymer can be adjusted, for example, by changing the type and ratio of the monomers used in preparing the core polymer.

[0083] Examples of monomers used to prepare the core polymer include vinyl chloride monomers such as vinyl chloride and vinylidene chloride; vinyl acetate monomers such as vinyl acetate; aromatic vinyl monomers such as styrene, α-methylstyrene, styrene sulfonic acid, butoxystyrene, and vinylnaphthalene; vinylamine monomers such as vinylamine; vinylamide monomers such as N-vinylformamide and N-vinylacetamide; methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and the like. Examples of the monomers include (meth)acrylic acid ester monomers such as acrylate, ethyl methacrylate, butyl methacrylate, and cyclohexyl methacrylate; (meth)acrylamide monomers such as acrylamide and methacrylamide; (meth)acrylonitrile monomers such as acrylonitrile and methacrylonitrile; fluorine-containing (meth)acrylic acid ester monomers such as 2-(perfluorohexyl)ethyl methacrylate and 2-(perfluorobutyl)ethyl acrylate; maleimide; and maleimide derivatives such as phenylmaleimide. These monomers may be used alone or in combination of two or more at any ratio. In the present invention, (meth)acrylic means acrylic and / or methacrylic, and (meth)acrylonitrile means acrylonitrile and / or methacrylonitrile.

[0084] Among these monomers, from the viewpoint of further firmly bonding battery components together via the adhesive material, it is preferable to use at least a (meth)acrylic acid ester monomer as the monomer used to prepare the core polymer, and a combination of a (meth)acrylic acid ester monomer and an aromatic vinyl monomer, or a combination of a (meth)acrylic acid ester monomer and a (meth)acrylonitrile monomer is more preferable, and a combination of a (meth)acrylic acid ester monomer and an aromatic vinyl monomer is particularly preferable. That is, the core polymer preferably contains at least a (meth)acrylic acid ester monomer unit, more preferably a (meth)acrylic acid ester monomer unit and an aromatic vinyl monomer unit or a (meth)acrylonitrile monomer unit, and even more preferably a (meth)acrylic acid ester monomer unit and an aromatic vinyl monomer unit. In the present invention, "containing a monomer unit" means that "a polymer obtained using the monomer contains a repeating unit derived from the monomer." In the present invention, the term "(meth)acrylic acid ester monomer" refers to a monofunctional (meth)acrylic acid ester monomer having only one polymerization reactive group.

[0085] From the viewpoint of further firmly bonding battery components together via the adhesive material, the proportion of (meth)acrylic acid ester monomer units in the core polymer is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 20% by mass or more, with all repeating units (all monomer units) contained in the core polymer being 100% by mass, and is preferably 80% by mass or less, and more preferably 70% by mass or less. Furthermore, when the core polymer contains (meth)acrylic acid ester monomer units and aromatic vinyl monomer units, the proportion of the aromatic vinyl monomer units in the core polymer is preferably 15% by mass or more, more preferably 20% by mass or more, and particularly preferably 25% by mass or more, and is preferably 95% by mass or less, more preferably 80% by mass or less, and particularly preferably 65% ​​by mass or less, based on 100% by mass of all repeating units (all monomer units) contained in the core polymer, from the viewpoint of further firmly bonding the battery components together via the adhesive material. Furthermore, when the core polymer contains (meth)acrylic acid ester monomer units and (meth)acrylonitrile monomer units, the proportion of the (meth)acrylonitrile monomer units in the core polymer is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 15% by mass or more, and is preferably 30% by mass or less, and more preferably 25% by mass or less, based on 100% by mass of all repeating units (all monomer units) contained in the core polymer, from the viewpoint of further firmly bonding the battery components together via the adhesive material.

[0086] The core polymer may also contain an acid group-containing monomer unit. Examples of the acid group-containing monomer include a monomer having an acid group, such as a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, or a monomer having a phosphoric acid group.

[0087] Examples of the monomer having a carboxylic acid group include monocarboxylic acids and dicarboxylic acids. Examples of the monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid. Examples of the dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid. Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth)allyl sulfonic acid, (meth)acrylic acid-2-ethyl sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid. Furthermore, examples of the monomer having a phosphate group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate. In the present invention, (meth)allyl means allyl and / or methallyl, and (meth)acryloyl means acryloyl and / or methacryloyl. Among these, as the acid group-containing monomer, a monomer having a carboxylic acid group is preferred, and among these, a monocarboxylic acid is preferred, and (meth)acrylic acid is more preferred. The acid group-containing monomer may be used alone or in combination of two or more kinds in any ratio.

[0088] The proportion of the acid group-containing units in the core polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less, based on 100% by mass of all repeating units (total monomer units) contained in the core polymer. By keeping the proportion of the acid group-containing units within the above range, the dispersibility of the core polymer can be improved during preparation of the particulate polymer, and it can be made easier to form a shell portion that partially covers the outer surface of the core polymer.

[0089] In addition to the above-mentioned monomer units, the core polymer preferably contains a crosslinkable monomer unit. The crosslinkable monomer is a monomer that can form a crosslinked structure during or after polymerization by heating or irradiation with energy rays.

[0090] Examples of crosslinkable monomers include polyfunctional monomers having two or more polymerization reactive groups. Examples of such polyfunctional monomers include divinyl monomers such as divinylbenzene, 1,3-butadiene, isoprene, and allyl methacrylate; di(meth)acrylic acid ester monomers such as ethylene dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butylene glycol diacrylate; tri(meth)acrylic acid ester monomers such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; ethylenically unsaturated monomers containing epoxy groups such as allyl glycidyl ether and glycidyl methacrylate; and γ-methacryloxypropyltrimethoxysilane. Among these, di(meth)acrylic acid ester monomers are more preferred. These may be used alone or in combination of two or more in any ratio.

[0091] Furthermore, the proportion of crosslinkable monomer units in the core polymer is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and particularly preferably 0.4% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less, where the total mass of all repeating units (total monomer units) contained in the core polymer is 100% by mass. By keeping the proportion of crosslinkable monomer units within the above range, the battery components can be more firmly bonded together via the adhesive material.

[0092] The glass transition temperature of the polymer in the shell portion of the particulate polymer is preferably 70°C or higher, more preferably 80°C or higher, and particularly preferably 90°C or higher, and is preferably 140°C or lower, more preferably 130°C or lower, and particularly preferably 120°C or lower. If the glass transition temperature of the polymer in the shell portion is 70°C or higher, the output characteristics of the secondary battery can be improved. On the other hand, if the glass transition temperature of the polymer in the shell portion is 140°C or lower, the battery components can be more firmly bonded to each other via the adhesive material. The glass transition temperature of the polymer can be measured by the method described in the examples of this specification. The glass transition temperature of the shell polymer can be adjusted, for example, by changing the type and ratio of the monomers used to prepare the shell polymer.

[0093] From the viewpoint of maintaining the shape of the particulate polymer after bonding the battery components together and suppressing an increase in resistance, the glass transition temperature of the polymer in the shell portion is preferably at least 10°C higher, more preferably at least 30°C higher, and particularly preferably at least 50°C higher than the glass transition temperature of the polymer in the core portion described above.

[0094] Examples of the monomers used to prepare the shell polymer include the same monomers as those exemplified as the monomers that can be used to produce the core polymer. These monomers may be used alone or in combination of two or more types in any ratio.

[0095] Among these monomers, aromatic vinyl monomers are preferably used as the monomers used to prepare the shell polymer, from the viewpoint of further firmly bonding the battery components together via the adhesive material, i.e., the shell polymer preferably contains aromatic vinyl monomer units.

[0096] From the viewpoint of bonding battery components together more firmly in the electrolyte via the adhesive material, the proportion of aromatic vinyl monomer units in the polymer of the shell portion is preferably 85% by mass or more, more preferably 90% by mass or more, particularly preferably 95% by mass or more, and preferably 99% by mass or less, where all repeating units (all monomer units) contained in the polymer of the shell portion are taken as 100% by mass.

[0097] The shell polymer may contain, in addition to aromatic vinyl monomer units, acid group-containing monomer units. Examples of the acid group-containing monomer include monomers having an acid group, such as monomers having a carboxylic acid group, monomers having a sulfonic acid group, and monomers having a phosphoric acid group. Specifically, the acid group-containing monomer may be the same as the acid group-containing monomer that can be used to form the core. Among these, as the acid group-containing monomer, a monomer having a carboxylic acid group is preferred, among which a monocarboxylic acid is more preferred, and (meth)acrylic acid is even more preferred. The acid group-containing monomer may be used alone or in combination of two or more kinds in any ratio.

[0098] The proportion of the acid group-containing monomer units in the polymer of the shell portion is preferably 0.1% by mass or more, more preferably 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less, where the total repeating units (total monomer units) contained in the polymer of the shell portion is taken as 100% by mass. By keeping the proportion of the acid group-containing monomer units within the above range, the dispersibility of the particulate polymer can be improved, and the battery components can be bonded together even more firmly via the adhesive material.

[0099] In the particulate polymer having a core-shell structure, the mass ratio of the core polymer to the shell polymer (core / shell) is preferably 5 / 5 or more, more preferably 6 / 4 or more, and preferably 9 / 1 or less, and more preferably 8 / 2 or less. When the mass ratio of the core polymer to the shell polymer (core / shell) is within the above-mentioned range, the battery components can be more firmly bonded to each other in the electrolyte solution via the adhesive material.

[0100] The volume average particle diameter of the particulate polymer having a core-shell structure is preferably 100 nm or more, more preferably 300 nm or more, and is preferably 1000 nm or less, more preferably 900 nm or less, even more preferably 800 nm or less, and still more preferably 700 nm or less. When the volume average particle diameter of the particulate polymer having a core-shell structure is within the above-mentioned range, the battery components can be more firmly bonded to each other via the adhesive material. The volume average particle size of the particulate polymer can be measured by the method described in the examples of this specification.

[0101] The particulate polymer having the core-shell structure can be prepared by, for example, using a monomer for the core polymer and a monomer for the shell polymer, polymerizing them stepwise while changing the ratio of these monomers over time. Specifically, the particulate polymer can be prepared by a continuous multi-stage emulsion polymerization method or multi-stage suspension polymerization method in which the polymer in the earlier stage is successively coated with the polymer in the later stage.

[0102] Therefore, an example of obtaining a particulate polymer having the above core-shell structure by a multistage emulsion polymerization method will be described below.

[0103] For the polymerization, an emulsifier may be used according to a conventional method, such as an anionic surfactant such as sodium dodecylbenzenesulfonate or sodium dodecyl sulfate, a nonionic surfactant such as polyoxyethylene nonylphenyl ether or sorbitan monolaurate, or a cationic surfactant such as octadecylamine acetate. Furthermore, a polymerization initiator may be used, such as a peroxide such as t-butylperoxy-2-ethylhexanoate, potassium persulfate, or cumene peroxide, or an azo compound such as 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)-propionamide) or 2,2'-azobis(2-amidinopropane) hydrochloride.

[0104] The polymerization procedure is as follows: first, a monomer for forming the core part and an emulsifier are mixed and emulsion-polymerized all at once to obtain a particulate polymer for forming the core part. Then, a monomer for forming the shell part is polymerized in the presence of the particulate polymer for forming the core part, thereby obtaining a particulate polymer having the above-mentioned core-shell structure.

[0105] In this case, when preparing a particulate polymer in which the outer surface of the core part is partially covered with the shell part, it is preferable to supply the monomer that forms the polymer for the shell part to the polymerization system in multiple divided portions or continuously. By supplying the monomer that forms the polymer for the shell part to the polymerization system in divided portions or continuously, the polymer that forms the shell part is formed in a particulate form, and this particle is bonded to the core part, thereby forming the shell part that partially covers the core part.

[0106] =Particulate polymer not having a core-shell structure= The adhesive material may contain a particulate polymer not having a core-shell structure in addition to the particulate polymer having the core-shell structure described above.

[0107] Here, the glass transition temperature of the particulate polymer not having a core-shell structure is preferably -40°C or higher, more preferably -35°C or higher, even more preferably -30°C or higher, and preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower. If the glass transition temperature of the particulate polymer not having a core-shell structure is -40°C or higher, battery components can be more firmly bonded to each other via the adhesive material. On the other hand, if the glass transition temperature of the particulate polymer not having a core-shell structure is 0°C or lower, the polymerization stability of the particulate polymer can be ensured.

[0108] The monomer used to prepare the particulate polymer without a core-shell structure may be the same as the monomer exemplified as the monomer that can be used to prepare the core polymer of the particulate polymer with a core-shell structure.For example, the monomer used to prepare the particulate polymer without a core-shell structure is preferably a (meth)acrylic acid ester monomer, an aromatic vinyl monomer, an acid group-containing monomer, or a crosslinkable monomer.In addition, one type of such monomer may be used alone, or two or more types may be used in combination at any ratio.

[0109] From the viewpoint of further firmly bonding battery components together via the adhesive material, the proportion of (meth)acrylic acid ester monomer units in the particulate polymer not having a core-shell structure is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, and is preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less, where all repeating units (total monomer units) contained in the polymer are 100% by mass.

[0110] From the viewpoint of further firmly bonding battery components together via the adhesive material, the proportion of aromatic vinyl monomer units in the particulate polymer not having a core-shell structure is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, where all repeating units (total monomer units) contained in the polymer are 100% by mass.

[0111] The proportion of the acid group-containing monomer units in the particulate polymer having no core-shell structure is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less, based on 100% by mass of all repeating units (total monomer units) contained in the polymer. By keeping the proportion of the acid group-containing units in the particulate polymer having no core-shell structure within the above range, the dispersibility of the particulate polymer can be improved.

[0112] From the viewpoint of further firmly bonding battery components together via the adhesive material, the proportion of crosslinkable monomer units in the particulate polymer not having a core-shell structure is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, with all repeating units (total monomer units) contained in the polymer being 100% by mass, preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less.

[0113] The volume average particle diameter of the particulate polymer having no core-shell structure is preferably 50 nm or more, more preferably 100 nm or more, and even more preferably 200 nm or more, and is preferably 600 nm or less, more preferably 500 nm or less, and even more preferably 400 nm or less. When the volume average particle diameter of the particulate polymer having no core-shell structure is within the above-mentioned range, the battery components can be more firmly bonded to each other via the adhesive material.

[0114] The particulate polymer having no core-shell structure is not particularly limited, and can be prepared, for example, by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water. Here, the ratio of each monomer in the monomer composition is usually the same as the ratio of each monomer unit in the particulate polymer having no core-shell structure. The polymerization method and polymerization reaction are not particularly limited, and known polymerization methods and polymerization reactions can be used.

[0115] -others- The adhesive material present in the electrode tab peripheral region P and the adhesive material present in the other region Q may be the same or different. Therefore, the above-mentioned "area S where the adhesive material is densely applied" and "area T where the adhesive material is sparsely applied" may be coated with the same adhesive material or different adhesive materials.

[0116] In the above-mentioned section "Method of Applying Adhesive Material," a case was described in which the adhesive material is applied so that "areas S where the adhesive material is densely applied" and "areas T where the adhesive material is sparsely applied" exist on the surface Z, but the laminate in the secondary battery of the present invention is not limited to this, and the adhesive material can also be applied so that a "coated area S1" exists instead of the "area S where the adhesive material is densely applied," and a "coated area S2" exists instead of the "area T where the adhesive material is sparsely applied." That is, the adhesive material can also be applied so that a "coated area S1" and a "coated area S2" exist on the surface Z.

[0117] Here, the coverage rate and / or basis weight of the adhesive material in each of the "coating region S1" and the "coating region S2" can be set within the same range as the preferred range of the coverage rate and / or basis weight of the adhesive material in the above-mentioned "region S where the adhesive material is densely coated." Alternatively, the adhesive material may be coated so that the coverage rate and / or basis weight of the adhesive material are the same in the "coating region S1" and the "coating region S2."

[0118] The adhesive material applied to the "coating area S1" is different from the adhesive material applied to the "coating area S2." By appropriately selecting and using different adhesive materials as the adhesive material applied to the "coating area S1" and the adhesive material applied to the "coating area S2," the resistance A per unit area in the electrode tab peripheral area P can be made greater than the resistance B per unit area in the other area Q.

[0119] For example, the adhesive material to be applied to the "coating region S1" and the adhesive material to be applied to the "coating region S2" may use a particulate polymer M1 and a particulate polymer M2 having different swelling degrees.

[0120] Here, the swelling degree of the particulate polymer M1 contained in the adhesive material to be applied to the "coating area S1" with respect to the electrolyte solution (a solution in which LiPF6 is dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate / diethyl carbonate = 3 / 7 in volume ratio) is preferably 800% or more, more preferably 1000% or more, and preferably 1300% or less. Furthermore, the swelling degree of the particulate polymer M2 contained in the adhesive material to be applied to the "coating area S2" with respect to the electrolyte solution (a solution in which LiPF6 is dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate / diethyl carbonate = 3 / 7 in volume ratio) is preferably 110% or more, preferably less than 800%, more preferably 500% or less, and even more preferably 300% or less. By setting the swelling degree of the particulate polymers M1 and M2 within the above-mentioned predetermined range, the resistance A per unit area of ​​the electrode tab peripheral region P can be made larger than the resistance B per unit area of ​​the other region Q.

[0121] As the particulate polymers M1 and M2, for example, the particulate polymers having a core-shell structure described above in the section "Details of Adhesive Material" can be used. Among the particulate polymers having a core-shell structure described above, the particulate polymer M1 is preferably one in which the core polymer contains a (meth)acrylic acid ester monomer unit and a (meth)acrylonitrile monomer unit, and the particulate polymer M2 is preferably one in which the core polymer contains a (meth)acrylic acid ester monomer unit and an aromatic vinyl monomer unit.

[0122] Furthermore, for example, particulate polymers having different structures may be used for the adhesive material coated on the "coating region S1" and the adhesive material coated on the "coating region S2". More specifically, a particulate polymer having a core-shell structure may be used as the particulate polymer M3 contained in the adhesive material coated on the "coating region S1", and a particulate polymer not having a core-shell structure may be used as the particulate polymer M4 contained in the adhesive material coated on the "coating region S2". Here, for example, the particulate polymer M3 may be the particulate polymer having a core-shell structure described above in the "Details of Adhesive Material" section. Furthermore, for example, the particulate polymer M4 may be a particulate polymer consisting only of a polymer having the same composition as the core polymer in the particulate polymer having a core-shell structure described above in the "Details of Adhesive Material" section.

[0123] <<Laminate manufacturing method>> The method for producing a laminate in a secondary battery of the present invention includes a step (A) of preparing a bonded body and a step (B) of cutting the bonded body, and optionally, when the bonded body prepared in step (A) does not include a positive electrode, further includes a step (C) of bonding a positive electrode to the cut body obtained by cutting the bonded body in step (B). Note that, in addition to the above-mentioned steps (A), (B), and (C), the method for producing a laminate in a secondary battery of the present invention may further include a step of connecting electrode tabs (positive electrode tab and negative electrode tab) to the electrodes (positive electrode and negative electrode).

[0124] [Process (A)] Here, examples of the laminate prepared in step (A) include the following (I) and (II). (I) A laminated body (hereinafter, sometimes referred to as "laminated body (I)") comprising a long negative electrode raw sheet or negative electrode (hereinafter, "negative electrode raw sheet or negative electrode" may be referred to as "negative electrode material"), a long first separator raw sheet laminated to one surface of the negative electrode material, and a long second separator raw sheet laminated to the other surface of the negative electrode material, and optionally a positive electrode laminated to the surface of the first separator raw sheet opposite to the negative electrode material side. (II) A laminated body obtained by laminating, in this order, a negative electrode material made of a long negative electrode raw sheet, a long first separator raw sheet, a positive electrode, and a long second separator raw sheet (hereinafter, sometimes referred to as "laminate (II)").

[0125] In the method for producing a laminate in a secondary battery of the present invention, when the laminate (I) is prepared in step (A), a laminate is usually obtained that includes a negative electrode, a first separator bonded to one surface of the negative electrode, a positive electrode bonded to the surface of the first separator opposite to the negative electrode side, and a second separator bonded to the other surface of the negative electrode, as shown in FIG. 1, for example. When the laminate (I) does not have a positive electrode, the method for producing a laminate in the secondary battery of the present invention usually involves carrying out step (C) after step (B) to produce a laminate. In the method for producing a laminate in a secondary battery of the present invention, when a laminate (II) is prepared in step (A), a laminate is usually obtained that includes a negative electrode, a first separator bonded to one surface of the negative electrode, a positive electrode bonded to the surface of the first separator opposite to the negative electrode side, and a second separator bonded to the surface of the positive electrode opposite to the first separator side, as shown in FIG. 3, for example.

[0126] Here, the preparation of the bonded body in step (A) is usually carried out by applying an adhesive material to the bonding surfaces of the components to be bonded together and bonding the components constituting the bonded body together via the adhesive material. That is, step (A) includes step (a1) of applying the adhesive material to bonding surface Y between the negative electrode material and the separator raw sheet to be bonded to the negative electrode material, and may further include step (a2) of applying the adhesive material to bonding surface X between the separator raw sheet and the positive electrode.

[0127] The "separator raw sheet to be bonded to the negative electrode material" refers to the first separator raw sheet and the second separator raw sheet when the bonded body to be prepared is the bonded body (I), and refers to the first separator raw sheet when the bonded body is the bonded body (II). The adhesive material may be applied to only one of the members, or to both of the members to be bonded to each other.

[0128] Specifically, in the step (A), for example, a laminate (I) can be prepared as shown in FIG.

[0129] 10, a long first separator blank 10A unwound from a first separator blank roll is bonded to one surface of a long negative electrode blank 20A unwound from a negative electrode blank roll via an adhesive material supplied from a coater 51, and a long second separator blank 30A unwound from a second separator blank roll is bonded to the other surface of the negative electrode material 20A via an adhesive material supplied from a coater 52. The bonding can be performed using, for example, pressure rollers 61 and 62. Then, positive electrodes 40 are bonded at a predetermined arrangement pitch to the surface of the first separator blank 10A opposite to the negative electrode blank 20A via an adhesive material supplied from a coater 53, thereby obtaining a bonded body (I) including positive electrodes. In FIG. 10 , an adhesive material is supplied from a coating machine 54 to the surface of the second separator raw roll 30A opposite to the negative electrode raw roll 20A side, and the laminate is cut between longitudinally adjacent positive electrodes 40 to obtain a laminate, which is then stacked to produce a laminate. This ensures that the laminates can be well bonded to each other.

[0130] FIG. 11 is an explanatory diagram showing an example of the coating machine (nozzle head) in FIG. In FIG. 11, droplets 50 of adhesive material are applied onto a substrate 60 through nozzles 55 of coaters 51-54.

[0131] The method for preparing the laminate in step (A) is not limited to the above-mentioned example. For example, in FIG. 10, after cutting the laminate, adhesive material may be supplied from a coating machine 54 to the obtained cut pieces.

[0132] -Anode materials and cathodes- Here, the electrode (negative electrode or positive electrode) is not particularly limited, and for example, an electrode obtained by cutting a long electrode raw sheet (negative electrode raw sheet or positive electrode raw sheet) can be used. The electrode raw sheet (negative electrode raw sheet or positive electrode raw sheet) can be an electrode raw sheet made of an electrode base material formed by forming an electrode composite layer (negative electrode composite layer or positive electrode composite layer) on one or both sides of a long current collector, or an electrode raw sheet formed by further forming a porous membrane layer on the electrode composite layer of the electrode base material. The current collector, electrode mixture layer, and porous membrane layer are not particularly limited, and any current collector, electrode mixture layer, and porous membrane layer that can be used in the field of secondary batteries, such as those described in JP 2013-145763 A, can be used. Here, the porous membrane layer refers to a layer containing non-conductive particles, such as those described in JP 2013-145763 A.

[0133] -Separator raw material- The separator raw sheet is not particularly limited, and for example, a separator raw sheet made of a long separator substrate, or a separator raw sheet made of a long separator substrate with a porous membrane layer formed on one or both sides thereof can be used. The separator substrate and the porous membrane layer are not particularly limited, and any separator substrate and porous membrane layer that can be used in the field of secondary batteries, such as those described in JP-A-2012-204303 and JP-A-2013-145763, can be used.

[0134] In the step (a1) of applying an adhesive material to the bonding surface Y of the separator raw sheet to be bonded to the negative electrode material, or the step (a2) of applying an adhesive material to the bonding surface X of the separator raw sheet to be bonded to the positive electrode, it is preferable to apply the adhesive material to the bonding surface Z, which is at least one of the bonding surfaces X and Y, so that the coverage E of the adhesive material in the electrode tab peripheral region P described above is greater than the coverage F of the adhesive material in the other region Q. This can further suppress metal deposition on the electrode surface during charging of the secondary battery. Note that, as a method for applying the adhesive material to the surface Z so that the coverage rate E of the adhesive material in the electrode tab peripheral region P is greater than the coverage rate F of the adhesive material in the other regions Q, for example, the adhesive material application method described above in the section "Surface Z, Electrode Tabs (Positive Electrode Tab, Negative Electrode Tab), and Electrode Tab Peripheral Region P" can be used. The coverage rate E of the adhesive material in the electrode tab peripheral region P, the coverage rate F of the adhesive material in the other regions Q, and the range of the ratio (E / F) of the coverage rate E to the coverage rate F can also be set within the preferred ranges described above in the same section.

[0135] In the step (a2), an adhesive material is applied to the bonding surface between the separator raw sheet and the positive electrode. Specifically, when a bonded body including a positive electrode is prepared in step (A) (for example, FIG. 10 ), and when a bonded body (a bonded body without a positive electrode) in which an adhesive material is applied in advance to the position where the positive electrode will be bonded after cutting is prepared in step (A), the adhesive material is applied to the bonding surface between the separator raw sheet and the positive electrode in step (a2). That is, for example, in FIG. 10, an adhesive material is applied from a coater 53 to the bonding surface between the first separator web 10A and the positive electrode 40.

[0136] In step (A), as shown in FIG. 10, for example, an adhesive material may be supplied to one surface of the bonded body (in FIG. 10, the surface of the second separator raw material 30A opposite to the negative electrode raw material 20A side) so that the laminates can be well bonded to each other when the laminates are stacked to produce the laminate.

[0137] [Process (B)] In step (B), the bonded body is cut using a cutting machine 70. When the bonded body having the positive electrode is cut in step (B), the cut body obtained becomes a laminate. Here, the cutter 70 can be any cutter that can be used in the field of secondary battery manufacturing, such as a cutter that sandwiches the bonded body with cutting blades from both sides in the thickness direction of the bonded body to cut it.

[0138] In the step (B) carried out after the step (A), as described above, the laminate can be cut well while preventing the separator from being peeled off from the negative electrode.

[0139] [Process (C)] In step (C), which can be optionally performed, when the bonded body not having a positive electrode is cut in step (B), a positive electrode is bonded to the cut body obtained by cutting the bonded body in step (B) to obtain a laminate.

[0140] <Electrolyte> The electrolyte solution is usually an organic electrolyte solution in which a supporting electrolyte is dissolved in an organic solvent. For example, when the secondary battery is a lithium ion secondary battery, a lithium salt can be used as the supporting electrolyte. Examples of lithium salts include LiPF6, LiAsF6, LiBF4, LiSbF6, LiAlCl4, LiClO4, CF3SO3Li, CF4F9SO3Li, CF3COOLi, (CF3CO)2NLi, (CF3SO2)2NLi, and (C2F5SO2)NLi. Among these, LiPF6, LiClO4, and CF3SO3Li are preferred, with LiPF6 being particularly preferred, as they are easily soluble in solvents and exhibit a high degree of dissociation. One type of electrolyte may be used alone, or two or more types may be used in combination at any ratio. Generally, the use of a supporting electrolyte with a higher degree of dissociation tends to result in higher lithium ion conductivity, so the lithium ion conductivity can be adjusted by the type of supporting electrolyte.

[0141] The organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte. For example, carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), ethyl methyl carbonate (EMC), and vinylene carbonate (VC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; and sulfur-containing compounds such as sulfolane and dimethyl sulfoxide are preferably used. A mixture of these solvents may also be used. Among these, carbonates are preferred because of their high dielectric constant and wide stable potential range. Generally, the lower the viscosity of the solvent used, the higher the lithium ion conductivity tends to be, so the lithium ion conductivity can be adjusted by the type of solvent. The concentration of the electrolyte in the electrolytic solution can be adjusted as appropriate, and known additives can be added to the electrolytic solution.

[0142] The secondary battery of the present invention can be produced, for example, by stacking laminates to form a stack, which can then be rolled or folded, as necessary, according to the battery shape, placed in a device container (battery container), and then injecting an electrolyte into the device container and sealing it. The stack may be the laminate itself, or a plurality of laminates may be stacked together. The stack may also be produced by stacking a laminate with additional battery components (electrodes and / or separators, etc.). The secondary battery of the present invention may also be provided with a fuse, an overcurrent protection element such as a PTC element, an expanded metal, a lead plate, etc., as necessary to prevent internal pressure buildup, overcharging and overdischarging, etc. The secondary battery may have any shape, such as a coin type, a button type, a sheet type, a cylindrical type, a rectangular type, or a flat type.

[0143] (Secondary battery manufacturing method) The method for producing a secondary battery of the present invention is a method for producing a secondary battery having a laminate formed by laminating a positive electrode, a separator, and a negative electrode in this order, and is characterized by including a step (coating step) of applying an adhesive material under predetermined conditions to surface Z, which is at least one of surface X where the positive electrode and the separator are attached and surface Y where the negative electrode and the separator are attached. Furthermore, according to the method for producing a secondary battery of the present invention, a secondary battery can be produced in which metal deposition on the electrode surface during charging is suppressed. Furthermore, according to the manufacturing method of the present invention, the secondary battery of the present invention described above can be manufactured efficiently. The method for producing a secondary battery of the present invention may include other steps in addition to the coating step described above.

[0144] <Coating process> In the coating process, when at least one of the bonding surface X between the positive electrode and the separator and the bonding surface Y between the negative electrode and the separator is defined as surface Z, and the length of the connection side of either the positive electrode tab connected to the positive electrode or the negative electrode tab connected to the negative electrode is defined as L, the adhesive material is coated on surface Z so that the coverage rate E of the adhesive material in a rectangular region P (electrode tab peripheral region P) of surface Z, whose pair of opposite sides is the connection side and a line segment whose distance from the connection side is 0.3L, is greater than the coverage rate F of the adhesive material in a region Q (other region Q) other than region P on surface Z. As a method for applying the adhesive material to the surface Z so that the coverage rate E of the adhesive material in the electrode tab peripheral region P described above is greater than the coverage rate F of the adhesive material in the other region Q, for example, the adhesive material application method described in the section on "Secondary battery" can be used. The coverage rate E of the adhesive material in the electrode tab peripheral region P, the coverage rate F of the adhesive material in the other region Q, and the range of the ratio of the coverage rate E to the coverage rate F (E / F) can also be set within the preferred ranges described above in the "Secondary Battery" section. The positive electrode, separator, negative electrode, and adhesive material used in the coating step can be those described above in the "Secondary battery" section.

[0145] <Other processes> Other steps include, for example, a lamination step, an electrode tab connection step, and an assembly step.

[0146] <<Lamination process>> In the lamination step, after applying the adhesive material to surface Z under the above-mentioned predetermined conditions, the positive electrode, separator, and negative electrode are laminated in this order to obtain a laminate.

[0147] <<Electrode tab connection process>> In the electrode tab connecting step, electrode tabs (positive electrode tab and negative electrode tab) are connected to the electrodes (positive electrode and negative electrode). It should be noted that a laminate can also be obtained by using the method for manufacturing a laminate described above in the section "Secondary Battery" and performing the coating step, laminating step, and electrode tab connecting step as part of the manufacturing method for the laminate.

[0148] <<Assembly process>> The assembly process is a process of assembling a secondary battery using a laminate and an electrolytic solution, and is, for example, a process in which additional battery components (electrodes and / or separators, etc.) are further laminated as needed on the laminate obtained by stacking the laminates, and then the resulting laminate is placed in a battery container, and the battery container is injected with an electrolytic solution and sealed to complete the assembly. [Example]

[0149] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified. Furthermore, in a polymer produced by copolymerizing multiple types of monomers, the proportion of a monomer unit formed by polymerizing a certain monomer in the polymer usually coincides with the ratio (feed ratio) of the certain monomer to all the monomers used in the polymerization of the polymer, unless otherwise specified. In the Production Examples, Examples, and Comparative Examples, the glass transition temperature, volume average particle size, degree of swelling, shape of the adhesive material, basis weight of the coated area, dry adhesive strength between the electrode and the separator, lithium deposition rate on the negative electrode surface, and output characteristics were measured and evaluated by the following methods.

[0150] <Glass transition temperature> The aqueous dispersions of particulate polymers prepared in Preparation Examples 1 to 6 were dried at 130°C for 1 hour to prepare samples. A 10 mg sample was weighed into an aluminum pan and measured using a differential scanning calorimetry (DSC) analyzer (SII NanoTechnology, Inc., EXSTAR DSC6220) at a temperature range of -100°C to 500°C at a heating rate of 10°C / min according to the conditions specified in JIS Z8703. A differential scanning calorimetry (DSC) curve was obtained. An empty aluminum pan was used as a reference. The glass transition temperature (°C) was determined by the intersection of the baseline immediately before the endothermic peak of the DSC curve, where the differential signal (DDSC) was 0.05 mW / min / mg or greater, and the tangent to the DSC curve at the first inflection point after the endothermic peak.

[0151] <Volume average particle size> The volume average particle diameter of the particulate polymer prepared in each production example was measured by laser diffraction. Specifically, an aqueous dispersion solution (solid content concentration 0.1 mass%) containing the prepared particulate polymer was used as a sample, and the particle size distribution (volume basis) obtained using a laser diffraction particle size distribution analyzer (manufactured by Beckman Coulter, product name "LS-13 320") was used to obtain the particle diameter at which the cumulative volume calculated from the smallest diameter side reached 50%, which was defined as the volume average particle diameter D50 (nm).

[0152] <Swelling degree> The aqueous dispersion of particulate polymer prepared in each production example was dried, and approximately 0.2 g of the resulting dried product was pressed at a temperature of 200°C and a pressure of 5 MPa for 2 minutes to obtain a film. The obtained film was cut into 1 cm squares to prepare test pieces, and the mass W2 (g) of each test piece was measured. Next, the test piece was immersed in an electrolyte (a solution in which LiPF6 was dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate / diethyl carbonate = 3 / 7 by volume ratio) at a temperature of 60°C for 72 hours. Thereafter, the test piece was removed from the electrolyte, the mixed solvent on the surface was wiped off, and the mass W3 (g) of the test piece was measured. The swelling degree (%) was then calculated according to the following formula: Swelling rate (%) = W3 / W2 x 100

[0153] <Shape of adhesive material> The shape of the adhesive material applied to the bonded surfaces was observed using a laser microscope (Keyence Corporation, VR-3100).

[0154] <Adhesive material basis weight> For each region, the basis weight of the adhesive material was determined from the difference in mass per unit area between before the adhesive composition was supplied and after the adhesive composition was supplied and dried.

[0155] <Adhesion strength between electrode and separator> Under the same conditions as in each example and comparative example, a negative electrode coated with an adhesive material on one side and a separator were pressed for 10 seconds under pressing conditions of a temperature of 70°C and a pressure of 1 MPa, and the laminate after bonding (i.e., a laminate in which one negative electrode and one separator are bonded together via the adhesive material) was collected and used as a test piece. The test piece was placed with the negative electrode current collector side facing downward, and cellophane tape was attached to the surface of the negative electrode current collector side. The cellophane tape used was specified in JIS Z1522. The cellophane tape was fixed to a horizontal test table. One end of the separator was then pulled vertically upward at a pulling rate of 50 mm / min, and the stress when peeled off was measured. This measurement was performed a total of six times, and the average stress value was calculated as the peel strength, and the adhesion between the negative electrode and the separator was evaluated according to the following criteria: A higher peel strength indicates a higher adhesion between the electrode (negative electrode) and the separator. A: Peel strength is 1.5N / m or more B: Peel strength is 1.0 N / m or more and less than 1.5 N / m C: Peel strength is 0.5N / m or more and less than 1.0N / m D: Peel strength is less than 0.5 N / m

[0156] <Lithium deposition rate on the negative electrode surface> The manufactured lithium-ion secondary battery was fully charged to a depth of charge (SOC) of 100% at a constant current of 1 C in an environment at a temperature of -10°C. The fully charged secondary battery was disassembled, the negative electrode was removed, and the surface condition of the negative electrode composite layer of the negative electrode was observed. The area of ​​lithium deposited on the surface of the negative electrode composite layer was then measured, and the lithium deposition rate on the negative electrode surface = (area of ​​deposited lithium / surface area of ​​the negative electrode composite layer) × 100 (%) was calculated. Evaluation was then performed according to the following criteria. A lower lithium deposition rate on the negative electrode surface indicates that lithium deposition on the negative electrode surface during charging is more suppressed. A: Lithium deposition rate is less than 10% B: Lithium deposition rate is 10% or more and less than 15% C: Lithium deposition rate is 15% or more and less than 20% D: Lithium deposition rate is 20% or more

[0157] <Output characteristics> The fabricated lithium-ion secondary battery was charged at constant current and constant voltage (CCCV) up to 4.3 V in an atmosphere at 25°C to prepare a cell. The prepared cell was discharged to 3.0 V at constant currents of 0.2 C and 1 C in an atmosphere at -10°C to determine the electric capacity. The discharge capacity retention rate, expressed as the ratio of electric capacities (= (electric capacity at 1 C / electric capacity at 0.2 C) × 100 (%)), was then determined. These measurements were performed on five lithium-ion secondary battery cells, and the average value of the determined discharge capacity retention rate was evaluated as the output characteristics according to the following criteria. A higher value indicates better output characteristics. A: The average discharge capacity retention rate is 80% or more B: The average discharge capacity retention rate is 70% or more and less than 80% C: The average discharge capacity retention rate is 60% or more and less than 70% D: The average discharge capacity retention rate is less than 60%

[0158] (Production Example 1) <Production of Particulate Polymer 1> 100 parts of ion-exchanged water and 0.3 parts of ammonium persulfate were fed into a reactor equipped with a stirrer, the gas phase was replaced with nitrogen gas, and the temperature was raised to 80 °C. Meanwhile, in a separate vessel, 40 parts of ion-exchanged water, 0.2 parts of sodium dodecylbenzenesulfonate as an emulsifier, 40.3 parts of styrene as an aromatic monovinyl monomer, 27.3 parts of 2-ethylhexyl acrylate as a monofunctional (meth)acrylic acid ester monomer, 2.1 parts of methacrylic acid as an acidic group-containing monomer, and 0.3 parts of ethylene glycol dimethacrylate as a crosslinkable monomer were mixed to obtain a core-forming monomer composition. This core-forming monomer composition was continuously added to the reactor over 3 hours and subjected to a polymerization reaction at 80 °C. The polymerization was continued until the polymerization conversion reached 95%, yielding an aqueous dispersion containing the particulate polymer that constitutes the core. Next, a monomer composition for forming a shell portion, which contained 29.7 parts of styrene as an aromatic monovinyl monomer and 0.3 parts of methacrylic acid as an acidic group-containing monomer, was continuously fed to this aqueous dispersion over 60 minutes to continue polymerization. When the polymerization conversion rate reached 98%, the reaction was stopped by cooling to prepare an aqueous dispersion containing particulate polymer 1. The volume average particle size, swelling degree, and glass transition temperature of the obtained particulate polymer 1 were measured. The results are shown in Table 1. Furthermore, by observing the cross-sectional structure of the particulate polymer using a transmission electron microscope (TEM), it was confirmed that the particulate polymer has a core-shell structure in which the shell part partially covers the outer surface of the core part.

[0159] (Production Example 2) <Production of Particulate Polymer 2> In the production of the particulate polymer of Production Example 1, an aqueous dispersion of particulate polymer 2 having a core-shell structure was prepared in the same manner as in Production Example 1, except that instead of the core-forming monomer composition containing 40.3 parts of styrene as the aromatic monovinyl monomer, 27.3 parts of 2-ethylhexyl acrylate as the monofunctional (meth)acrylic acid ester monomer, 2.1 parts of methacrylic acid as the acidic group-containing monomer, and 0.3 parts of ethylene glycol dimethacrylate as the crosslinkable monomer, a core-forming monomer composition containing 17.0 parts of methyl methacrylate and 36.1 parts of butyl acrylate as the monofunctional (meth)acrylic acid ester monomer, 14.0 parts of acrylonitrile as the (meth)acrylonitrile monomer, 2.8 parts of methacrylic acid as the acidic group-containing monomer, and 0.1 parts of ethylene glycol dimethacrylate as the crosslinkable monomer was used. The results were then measured in the same manner as in Production Example 1.

[0160] <Production of Particulate Polymer 3> In the production of the particulate polymer of Production Example 1, an aqueous dispersion of particulate polymer 3 not having a core-shell structure was prepared in the same manner as in Production Example 1, except that instead of the core-forming monomer composition containing 40.3 parts of styrene as the aromatic monovinyl monomer, 27.3 parts of 2-ethylhexyl acrylate as the monofunctional (meth)acrylic acid ester monomer, 2.1 parts of methacrylic acid as the acidic group-containing monomer, and 0.3 parts of ethylene glycol dimethacrylate as the crosslinkable monomer, a monomer composition containing 57.6 parts of styrene as the aromatic monovinyl monomer, 39.0 parts of 2-ethylhexyl acrylate as the monofunctional (meth)acrylic acid ester monomer, 3.0 parts of methacrylic acid as the acidic group-containing monomer, and 0.4 parts of ethylene glycol dimethacrylate as the crosslinkable monomer was used, and no shell-forming monomer composition was added. Then, various measurements were performed in the same manner as in Production Example 1. The results are shown in Table 1.

[0161] (Production Example 4) <Production of Particulate Polymer 4> 90 parts of ion-exchanged water and 0.5 parts of ammonium persulfate were fed into a reactor equipped with a stirrer, the gas phase was replaced with nitrogen gas, and the temperature was raised to 80° C. Meanwhile, in a separate vessel, 15 parts of ion-exchanged water, 1.0 part of Neopelex G15 (manufactured by Kao Chemical Corporation) as an emulsifier, 70.0 parts of 2-ethylhexyl acrylate as a monofunctional (meth)acrylic acid ester monomer, 25.0 parts of styrene as an aromatic monovinyl monomer, 1.7 parts of allyl glycidyl ether and 0.3 parts of allyl methacrylate as crosslinkable monomers, and 3.0 parts of acrylic acid as an acidic group-containing monomer were mixed to obtain a monomer composition. This monomer composition was continuously added to the reactor over 4 hours to carry out polymerization. During the continuous addition, the reaction was carried out at a temperature of 80° C. After the continuous addition was completed, the mixture was stirred at 80° C. for an additional 3 hours to complete the reaction. The obtained aqueous dispersion was cooled to a temperature of 25°C, and then an aqueous sodium hydroxide solution was added thereto to adjust the pH to 8.0. Thereafter, steam was introduced to remove unreacted monomers, thereby obtaining an aqueous dispersion of particulate polymer 4 not having a core-shell structure. Various measurements were then carried out in the same manner as in Production Example 1. The results are shown in Table 1.

[0162] (Production Example 5) In the production of the particulate polymer of Production Example 1, an aqueous dispersion of particulate polymer 5 having a core-shell structure was prepared in the same manner as in Production Example 1, except that instead of the core-forming monomer composition containing 40.3 parts of styrene as the aromatic monovinyl monomer, 27.3 parts of 2-ethylhexyl acrylate as the monofunctional (meth)acrylic acid ester monomer, 2.1 parts of methacrylic acid as the acidic group-containing monomer, and 0.3 parts of ethylene glycol dimethacrylate as the crosslinkable monomer, a core-forming monomer composition containing 20.2 parts of styrene as the aromatic monovinyl monomer, 47.6 parts of 2-ethylhexyl acrylate as the monofunctional (meth)acrylic acid ester monomer, 2.1 parts of methacrylic acid as the acidic group-containing monomer, and 0.1 parts of ethylene glycol dimethacrylate as the crosslinkable monomer was used. Then, various measurements were performed in the same manner as in Production Example 1. The results are shown in Table 1.

[0163] (Production Example 6) An aqueous dispersion of a particulate polymer 6 having a core-shell structure was prepared in the same manner as in Production Example 5, except that in the production of the particulate polymer in Production Example 5, 100 parts of ion-exchanged water, 0.3 parts of ammonium persulfate, and 0.03 parts of sodium dodecylbenzenesulfonate as an emulsifier were supplied to a reactor equipped with a stirrer. Then, various measurements were carried out in the same manner as in Production Example 1. The results are shown in Table 1.

[0164] Example 1 <Preparation of Adhesive Composition> The aqueous dispersion of particulate polymer 1 obtained in Production Example 1 and the aqueous dispersion of particulate polymer 4 obtained in Production Example 4 were mixed so that the mass ratio of the solid contents was 100:10, and then ion-exchanged water was added to dilute the mixture so that the solid content concentration was 10.5%. Propylene glycol was further added to the obtained mixture to adjust the solid content concentration to 10%, thereby obtaining a bonding composition 1.

[0165] <Preparation of negative electrode substrate> A 5 MPa pressure vessel equipped with a stirrer was charged with 33 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 63.5 parts of styrene, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator. After thorough stirring, the mixture was heated to 50°C to initiate polymerization. When the polymerization conversion reached 96%, the reaction was stopped by cooling, yielding a mixture containing a binder (SBR) for the negative electrode composite layer. A 5% aqueous sodium hydroxide solution was added to the mixture containing the binder for the negative electrode composite layer, adjusting the pH to 8, and then the unreacted monomer was removed by heated vacuum distillation. The mixture was then cooled to 30°C or below to obtain an aqueous dispersion containing the desired binder for the negative electrode composite layer. Next, 100 parts of artificial graphite (volume average particle diameter: 15.6 μm) as the negative electrode active material, 1 part (solids equivalent) of a 2% aqueous solution of carboxymethylcellulose sodium salt (manufactured by Nippon Paper Industries Co., Ltd., product name "MAC350HC") as a viscosity modifier, and ion-exchanged water were mixed to adjust the solids concentration to 68%, and then further mixed at a temperature of 25°C for 60 minutes. The solids concentration was further adjusted to 62% with ion-exchanged water, and then further mixed at a temperature of 25°C for 15 minutes. To the resulting mixture, 1.5 parts (solids equivalent) of the aqueous dispersion containing the binder for the negative electrode composite layer and ion-exchanged water were added, and the final solids concentration was adjusted to 52%, and then further mixed for 10 minutes. This mixture was degassed under reduced pressure to obtain a slurry composition for secondary battery negative electrodes with good fluidity. The obtained slurry composition for secondary battery negative electrodes was applied to both sides of a 20 μm-thick copper foil current collector using a comma coater so that the dried film thickness was approximately 150 μm, and then dried. This drying was performed by conveying the copper foil at a speed of 0.5 m / min through an oven at a temperature of 60 ° C for 2 minutes. Then, the copper foil was heat-treated at a temperature of 120 ° C for 2 minutes to obtain a pre-pressed negative electrode blank. This pre-pressed negative electrode blank was rolled using a roll press to obtain a pre-pressed negative electrode blank with a negative electrode composite layer thickness of 80 μm.

[0166] <Preparation of positive electrode substrate> 100 parts of LiCoO2 with a volume average particle size of 12 μm as the positive electrode active material, 2 parts of acetylene black (manufactured by Denka Co., Ltd., product name "HS-100") as the conductive material, 2 parts of polyvinylidene fluoride (manufactured by Kureha Corporation, product name "#7208") as the binder in solids equivalent, and N-methylpyrrolidone as the solvent were mixed to a total solids concentration of 70%. These were mixed using a planetary mixer to obtain a slurry composition for secondary battery positive electrodes. The obtained slurry composition for secondary battery positive electrodes was applied to both sides of a 20 μm thick aluminum foil current collector using a comma coater so that the dried film thickness was approximately 150 μm, and then dried. This drying was performed by conveying the aluminum foil at a speed of 0.5 m / min in an oven at a temperature of 60 ° C for 2 minutes. Then, the aluminum foil was heat-treated at a temperature of 120 ° C for 2 minutes to obtain a positive electrode blank. The obtained positive electrode blank was then rolled using a roll press to obtain a pressed positive electrode blank having a positive electrode mixture layer.

[0167] <Preparing the separator roll> A separator substrate made of polypropylene (PP) (product name "Celgard 2500") was prepared.

[0168] <Manufacturing of laminate> Using the adhesive composition, negative electrode raw sheet, positive electrode raw sheet, and separator raw sheet thus prepared, a laminate was prepared as shown in Fig. 12. In Fig. 12, reference numeral 91 denotes a conveying roller, and reference numeral 92 denotes a heat roller. Specifically, while a negative electrode raw sheet 20A unwound from a negative electrode raw sheet roll was transported at a speed of 10 m / min, an adhesive composition was supplied from an inkjet head of an inkjet coating machine 52 (Konica Corporation, KM1024 (shear mode type)) onto one surface of the negative electrode raw sheet 20A, and a second separator raw sheet 30A unwound from a separator raw sheet roll and the negative electrode raw sheet 20A were bonded together with pressure rollers 61, 62. Furthermore, an adhesive composition was supplied from an inkjet head of an inkjet coating machine 51 (Konica Corporation, KM1024 (shear mode type)) onto the other surface of the negative electrode raw sheet 20A, and a laminate of a first separator raw sheet 10A unwound from a separator raw sheet roll and the negative electrode raw sheet 20A and the second separator raw sheet 30A was bonded together with pressure rollers 61, 62. Furthermore, an adhesive composition was supplied from the inkjet head of an inkjet coater 53 (Konica Corporation, KM1024 (shear mode type)) to the surface of the first separator raw roll 10A opposite the negative electrode raw roll 20A side, and a pre-cut positive electrode 40 was placed on it. Then, the laminate of the first separator raw roll 10A, the negative electrode raw roll 20A, and the second separator raw roll 30A and the positive electrode 40 were bonded together with pressure rollers 61 and 62. Then, an adhesive composition was supplied from the inkjet head of an inkjet coater 54 (Konica Corporation, KM1024 (shear mode type)) onto the positive electrode 40, and the laminate was cut with a cutter 70 to obtain a laminate in which the second separator, negative electrode, first separator, and positive electrode were stacked in this order. Here, at the end of each current collector of the positive electrode 40 and the negative electrode raw sheet 20A, a portion where no electrode composite layer (positive electrode composite layer or negative electrode composite layer) is formed is provided, and the portion is punched out in advance to form a tab of a desired size, and the stacking is performed so that the positive electrode tab and the negative electrode tab are arranged on the same edge side of the bonding surfaces X, Y (surface Z) between the electrode and the separator. The bonding using the pressure rollers 61 and 62 was carried out at a temperature of 70° C. and a pressure of 1 MPa. Furthermore, the supplied adhesive composition was dried by using a heat roller 92 as part of the conveying roller 91 (drying temperature: 70° C., drying time: 1 second).

[0169] Here, the adhesive compositions were supplied from the coating machines 51 to 54 as shown in Table 2. Specifically, in each of the bonding surfaces X and Y (surface Z) between the electrode and the separator, (1) a rectangular region N1 that completely encompasses a rectangular region P1 (positive electrode tab peripheral region P1) whose pair of opposite sides is the connection side (length L1) of the positive electrode tab 44 and a line segment that is 0.3L1 away from the connection side of the positive electrode tab 44, and (2) a rectangular region N2 that completely encompasses a rectangular region P2 (negative electrode tab peripheral region P2) whose pair of opposite sides is the connection side (length L2) of the negative electrode tab 28 and a line segment that is 0.3L2 away from the connection side of the negative electrode tab 28 are both designated as "regions S where the adhesive material is densely applied," and regions other than the above-mentioned "regions S where the adhesive material is densely applied" are designated as "regions T where the adhesive material is sparsely applied." The "coverage rate of the adhesive material" in the "region S where the adhesive material is densely applied" is 3.0%, and the "basis weight of the adhesive material" is 0.180 g / m. 2 The "coverage rate of adhesive material" in the "area T where adhesive material is sparsely applied" is 0.79%, and the "basis weight of adhesive material" is 0.044 g / m. 2The adhesive layer composition was applied (supplied) so that the adhesive layer composition was as follows: Note that the "adhesive material" in the "coverage rate of adhesive material" and "basis weight of adhesive material" both refer to the adhesive composition after it has been dried and the solvent has been removed. Here, (1) the positive electrode tab peripheral region P1 had an area of ​​3.2% of the area of ​​the bonding surface X, Y (surface Z), and (2) the negative electrode tab peripheral region P2 had an area of ​​3.2% of the area of ​​the bonding surface X, Y (surface Z). Furthermore, (1) the rectangular region N1 completely encompassing the positive electrode tab peripheral region P1 had an area of ​​5% of the area of ​​the bonding surface X, Y (surface Z), and (2) the rectangular region N2 completely encompassing the negative electrode tab peripheral region P2 had an area of ​​5% of the area of ​​the bonding surface X, Y (surface Z). Therefore, the above-mentioned "region S where the adhesive material is densely coated" (i.e., the sum of the areas of (1) rectangular region N1 and (2) rectangular region N2) had an area of ​​10% of the area of ​​the bonding surface X, Y (surface Z). The above-mentioned adhesive composition 1 was used as the adhesive composition to be coated in both the "region S where the adhesive material is densely coated" and the "region T where the adhesive material is sparsely coated". The adhesive composition was applied in a dotted pattern in both the "region S where the adhesive material is densely coated" and the "region T where the adhesive material is sparsely coated". When the dried adhesive composition (the dried adhesive material) was observed with a laser microscope, it was found that a plurality of adhesive materials arranged in a minute dotted pattern were present on the bonding surface. In both the "region S where the adhesive material is densely coated" and the "region T where the adhesive material is sparsely coated", the dot size of the adhesive material arranged in a dotted pattern was 40 μm in diameter.

[0170] As described above, the positive electrode tab peripheral region P1 was composed only of the portion corresponding to the "region S where the adhesive material is densely applied." Therefore, the coverage rate E of the adhesive material in the negative electrode tab peripheral region P2 was 3.0%, and the basis weight of the adhesive material was 0.180 g / m 2On the other hand, in the region Q2 (other region Q2) other than the negative electrode tab peripheral region P2, a portion corresponding to the "region S where the adhesive material is densely applied" and a portion corresponding to the "region T where the adhesive material is sparsely applied" were mixed. The coverage rate F of the adhesive material in the other region Q2 was 0.95%, and the basis weight of the adhesive material was 0.054 g / m 2 It was. In addition, when a certain region U contains a mixture of a portion corresponding to the "region S where the adhesive material is densely applied" and a portion corresponding to the "region T where the adhesive material is sparsely applied," the coverage rate and basis weight of the adhesive material in the region U can be calculated using the following formulas. (Coverage rate of adhesive material in region U) = (Coverage rate of adhesive material in region S where adhesive material is densely applied) × (Proportion of region S where adhesive material is densely applied to the entire region U) + (Coverage rate of adhesive material in region T where adhesive material is sparsely applied) × (Proportion of region T where adhesive material is sparsely applied to the entire region U) (Basis weight of adhesive material in region U) = (Basis weight of adhesive material in region S where adhesive material is densely applied) × (Proportion of region S where adhesive material is densely applied to the entire region U) + (Basis weight of adhesive material in region T where adhesive material is sparsely applied) × (Proportion of region T where adhesive material is sparsely applied to the entire region U) The dry adhesive strength of the laminate was then evaluated, and the results are shown in Table 2.

[0171] <Secondary battery manufacturing and resistance measurement> The fabricated laminate was wrapped in an aluminum packaging exterior as an exterior packaging, and an electrolyte (solvent: ethylene carbonate / diethyl carbonate / vinylene carbonate = 68.5 / 30 / 1.5 (volume ratio), electrolyte: 1M LiPF6) was injected. The opening of the aluminum packaging exterior was then heat-sealed at 150°C to produce a lithium-ion secondary battery. After the electrolyte injection, the battery was left standing at 25°C for 5 hours. Next, the battery was charged at 25°C and a constant current of 0.2C to a cell voltage of 3.65V, followed by aging at 60°C for 12 hours. The battery was then discharged at 25°C and a constant current of 0.2C to a cell voltage of 3.00V. Subsequently, CC-CV charging (upper limit cell voltage: 4.30V) was performed at a constant current of 0.2C, followed by CC discharging at a constant current of 0.2C to 3.00V. Thereafter, the battery was charged to a state of charge (SOC) of 50% and disassembled in an inert gas atmosphere. 2 Three electrodes were randomly punched out so that the electrode group was equal to the diameter of the negative electrode tab peripheral region P2. After joining a tab lead to each, they were wrapped in an aluminum packaging exterior as an exterior material, and the above-mentioned electrolyte was poured into them to produce three secondary batteries consisting only of the negative electrode tab peripheral region P2. The produced batteries were discharged at a discharge rate of 3C for a discharge time of 10 seconds, and the average value of the DC resistance values ​​was taken as the resistance A2 of the negative electrode tab peripheral region P2. Note that the "DC resistance" referred to here refers to the resistance value calculated using the following formula, where V0 is the voltage before discharge (0 seconds) and V1 is the voltage after 10 seconds. DC resistance=1cm 2 ×(V1-V0) / 3C current value In addition, as described above, 10 electrode groups were randomly punched out from the other region Q2 (excluding the negative electrode tab peripheral region P2) of the disassembled laminate, so that the effective area was 1 cm × 1 cm, and secondary batteries consisting only of the other region Q2 were fabricated in the same manner. The fabricated batteries were discharged under the same conditions as described above, and the average DC resistance value was taken as the resistance per unit area B2 of the other region Q. The resistance value ratio (A2 / B2) is shown in Table 2.

[0172] Five stacks of the above-prepared laminates were stacked and pressed at 70°C and 1 MPa for 10 seconds to produce a stack. This stack was then wrapped in an aluminum packaging exterior and filled with an electrolyte (solvent: ethylene carbonate / diethyl carbonate / vinylene carbonate = 68.5 / 30 / 1.5 (volume ratio); electrolyte: 1M LiPF6). The opening of the aluminum packaging exterior was then heat-sealed at 150°C to produce a stacked lithium-ion secondary battery with a capacity of 800 mAh. The lithium deposition rate on the negative electrode surface of the resulting secondary battery and its output characteristics were evaluated. The results are shown in Table 2.

[0173] Example 2 In the production of the laminate of Example 1, the adhesive composition, negative electrode raw sheet, positive electrode raw sheet, separator raw sheet, laminate, and secondary battery were produced and prepared in the same manner as in Example 1, except that the adhesive composition was supplied from the coating machines 51 to 54 as follows. Specifically, the region between the edge of the bonding surface X, Y (surface Z) between the electrode and separator on the side where both the positive electrode tab and the negative electrode tab are arranged and a straight line parallel to the edge is designated as the "region S where the adhesive material is densely coated" in Table 2, and the region other than the "region S where the adhesive material is densely coated" on the bonding surface X, Y (surface Z) is designated as the "region T where the adhesive material is sparsely coated," with the "coverage rate of the adhesive material" in the "region S where the adhesive material is densely coated" being 3.0% and the "basis weight of the adhesive material" being 0.180 g / m 2 The "coverage rate of adhesive material" in the "area T where adhesive material is sparsely applied" is 0.79%, and the "basis weight of adhesive material" is 0.044 g / m. 2 The adhesive layer composition was applied (supplied) so that the "area S where the adhesive material was densely applied" had an area of ​​20% of the area of ​​the bonding surfaces X and Y (surface Z).

[0174] By carrying out the coating as described above, the positive electrode tab peripheral region P1 was composed only of the portion corresponding to the "region S where the adhesive material is densely coated." Therefore, the coverage rate E of the adhesive material in the negative electrode tab peripheral region P2 was 3.0%, and the basis weight of the adhesive material was 0.180 g / m 2On the other hand, in the region Q2 (other region Q2) other than the negative electrode tab peripheral region P2, a portion corresponding to the "region S where the adhesive material is densely applied" and a portion corresponding to the "region T where the adhesive material is sparsely applied" were mixed. The coverage rate F of the adhesive material in the other region Q2 was 1.17%, and the basis weight of the adhesive material was 0.068 g / m 2 It was. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0175] Example 3 In the production of the laminate of Example 1, the center-to-center distance (pitch) of the adhesive composition supplied in dot form to the "region S where the adhesive material is densely applied" and the "region T where the adhesive material is sparsely applied" was adjusted to change only the dot size of the adhesive composition supplied in dot form from a diameter of 40 μm to a diameter of 80 μm without changing the coverage of the adhesive material in each of the "region S where the adhesive material is densely applied" and the "region T where the adhesive material is sparsely applied". As a result, the basis weight of the adhesive material in the "region S where the adhesive material is densely applied" was 0.124 g / m 2 The basis weight of the adhesive material in the "region T where the adhesive material is sparsely applied" is 0.031 g / m 2 Thereafter, in the same manner as in Example 1, an adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0176] Example 4 In the production of the laminate of Example 1, the center-to-center distance (pitch) of the adhesive composition supplied in dot form to the "region S where the adhesive material is densely applied" and the "region T where the adhesive material is sparsely applied" was adjusted to change only the dot size of the adhesive composition supplied in dot form from a diameter of 40 μm to a diameter of 20 μm without changing the coverage of the adhesive material in each of the "region S where the adhesive material is densely applied" and the "region T where the adhesive material is sparsely applied". As a result, the basis weight of the adhesive material in the "region S where the adhesive material is densely applied" was 0.158 g / m 2The basis weight of the adhesive material in the "region T where the adhesive material is sparsely applied" is 0.040 g / m 2 Thereafter, in the same manner as in Example 1, an adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0177] Example 5 In the production of the laminate of Example 1, the center-to-center distance (pitch) of the adhesive composition supplied in the form of dots to the "region T where the adhesive material is sparsely applied" was adjusted to change the coverage of the adhesive material in the "region T where the adhesive material is sparsely applied" from 0.79% to 0.35%, and the basis weight of the adhesive material was changed to 0.044 g / m 2 to 0.022 g / m 2 An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except for the above change. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0178] Example 6 In the production of the laminate of Example 1, the center-to-center distance (pitch) of the adhesive composition supplied in the form of dots to the "region T where the adhesive material is sparsely applied" was adjusted to change the coverage of the adhesive material in the "region T where the adhesive material is sparsely applied" from 0.79% to 0.20%, and the basis weight of the adhesive material was changed to 0.044 g / m 2 to 0.011 g / m 2 An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except for the above change. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0179] Example 7 In the production of the laminate of Example 1, the center-to-center distance (pitch) of the adhesive composition supplied in the form of dots to the "region T where the adhesive material is sparsely applied" was adjusted to change the coverage of the adhesive material in the "region T where the adhesive material is sparsely applied" from 0.79% to 1.40%, and the basis weight of the adhesive material was changed to 0.044 g / m 2 to 0.079 g / m 2 An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except for the above change. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0180] Example 8 In the production of the laminate of Example 1, the center-to-center distance (pitch) of the adhesive composition supplied in the form of dots to the "region S where the adhesive material is densely applied" was adjusted to change the coverage of the adhesive material in the "region S where the adhesive material is densely applied" from 3.00% to 5.60%, and the basis weight of the adhesive material was changed to 0.180 g / m 2 to 0.316 g / m 2 An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except for the above change. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0181] Example 9 In the production of the laminate of Example 1, the center-to-center distance (pitch) of the adhesive composition supplied in the form of dots to the "region S where the adhesive material is densely applied" was adjusted to change the coverage of the adhesive material in the "region S where the adhesive material is densely applied" from 3.00% to 12.57%, and the basis weight of the adhesive material was changed to 0.180 g / m 2 to 0.712 g / m 2 An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except for the above change. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0182] Example 10 In the production of the laminate of Example 1, the center-to-center distance (pitch) of the adhesive composition supplied in the form of dots to the "region S where the adhesive material is densely applied" was adjusted to change the coverage of the adhesive material in the "region S where the adhesive material is densely applied" from 3.00% to 1.40%, and the basis weight of the adhesive material was changed to 0.180 g / m 2 to 0.079 g / m 2 An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except for the above change. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0183] Example 11 In the production of the laminate of Example 1, the shape of the adhesive composition supplied in the "region S where the adhesive material is densely applied" and the "region T where the adhesive material is sparsely applied" was changed from dots to stripes, the coverage of the adhesive material in the "region S where the adhesive material is densely applied" was changed from 3.00% to 9.09%, and the basis weight of the adhesive material was changed to 0.180 g / m 2 to 0.400 g / m 2 The adhesive material coverage rate in the "area T where adhesive material is sparsely applied" was changed from 0.79% to 3.61%, and the adhesive material basis weight was changed to 0.044 g / m 2 to 0.100 g / m 2 An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except for the above change. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0184] Example 12 In the production of the laminate of Example 1, the adhesive composition to be applied to the "region S where the adhesive material is densely applied" and the "region T where the adhesive material is sparsely applied" was changed from adhesive composition 1 prepared in Production Example 1 to adhesive composition 4 prepared as follows. An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except that Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2. <Preparation of Adhesive Composition 4> Five parts of sodium dodecylbenzenesulfonate were added to 100 parts of ion-exchanged water and stirred using a disperser, and 10 parts of vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP; "LBG" manufactured by Arkema) powder was gradually added and stirred for two hours to obtain an aqueous dispersion of PVdF-HFP with a solids concentration of 10.5%. Propylene glycol was further added to the obtained aqueous dispersion to adjust the solids concentration to 10%, thereby obtaining adhesive composition 4.

[0185] Example 13 In the production of the laminate of Example 1, the area of ​​the "region S where the adhesive material is densely applied" was changed from 10% to 50% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "region T where the adhesive material is sparsely applied" was changed from 90% to 50% of the area of ​​the bonding surfaces X and Y. Except for this, the adhesive composition, the negative electrode raw sheet, the positive electrode raw sheet, the separator raw sheet, the laminate, and the secondary battery were produced and prepared in the same manner as in Example 1. By carrying out the coating as described above, the positive electrode tab peripheral region P1 was composed only of the portion corresponding to the "region S where the adhesive material is densely coated." Therefore, the coverage rate E of the adhesive material in the negative electrode tab peripheral region P2 was 3.0%, and the basis weight of the adhesive material was 0.180 g / m 2 On the other hand, in the region Q2 (other region Q2) other than the negative electrode tab peripheral region P2, a portion corresponding to the "region S where the adhesive material is densely applied" and a portion corresponding to the "region T where the adhesive material is sparsely applied" were mixed. The coverage rate F of the adhesive material in the other region Q2 was 1.86%, and the basis weight of the adhesive material was 0.110 g / m2 It was. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0186] Example 14 In the production of the laminate of Example 1, a "coated area S1" was used instead of the "area S where the adhesive material is densely coated," and the adhesive material coverage rate was 3.00% and the basis weight was 0.180 g / cm in the "coated area S1." 2 The adhesive composition 2 prepared as described below was applied so that the adhesive composition 2 was adhered to the bonding surfaces X and Y. The areas other than the "area S where the adhesive material is densely applied" were replaced with the "area T where the adhesive material is sparsely applied" to form a "coated area S2." The adhesive material was applied to the "coated area S2" so that the coverage rate was 3.00% and the basis weight was 0.180 g / cm. 2 The adhesive composition, the negative electrode raw sheet, the positive electrode raw sheet, the separator raw sheet, the laminate, and the secondary battery were produced and prepared in the same manner as in Example 1, except that the adhesive composition 1 was applied so ... Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 3. <Preparation of Adhesive Layer Composition 2> In preparing the adhesive layer composition of Example 1, the same procedure as in Example 1 was repeated except that the aqueous dispersion of the particulate polymer 2 having a core-shell structure obtained in Production Example 2 was used instead of the aqueous dispersion of the particulate polymer 1 having a core-shell structure obtained in Production Example 1, to obtain an adhesive composition 2.

[0187] Example 15 In the production of the laminate of Example 1, a "coated area S1" was used instead of the "area S where the adhesive material is densely coated," and the adhesive material coverage rate was 3.00% and the basis weight was 0.180 g / cm in the "coated area S1." 2 The adhesive composition 3 prepared as described below was applied so that the adhesive composition 3 was adhered to the bonding surfaces X and Y. The areas other than the "area S where the adhesive material is densely applied" were replaced with the "area T where the adhesive material is sparsely applied" to form a "coated area S2." The adhesive material was applied to the "coated area S2" so that the coverage rate was 3.00% and the basis weight was 0.180 g / cm. 2The adhesive composition, the negative electrode raw sheet, the positive electrode raw sheet, the separator raw sheet, the laminate, and the secondary battery were produced and prepared in the same manner as in Example 1, except that the adhesive composition 1 was applied so ... Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 3. <Preparation of Adhesive Layer Composition 3> In preparing the adhesive layer composition of Example 1, the same procedure as in Example 1 was repeated except that the aqueous dispersion of the particulate polymer 1 having a core-shell structure obtained in Production Example 1 was replaced with the aqueous dispersion of the particulate polymer 3 not having a core-shell structure obtained in Production Example 3.

[0188] Example 16 In the production of the laminate of Example 1, the adhesive composition to be applied to the "region S where the adhesive material is densely applied" and the "region T where the adhesive material is sparsely applied" was changed from adhesive composition 1 prepared in Production Example 1 to adhesive composition 5 prepared as follows. An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except that Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 4. <Preparation of Adhesive Layer Composition 5> In preparing the adhesive layer composition of Example 1, the same procedure as in Example 1 was repeated except that the aqueous dispersion of the particulate polymer 5 having a core-shell structure obtained in Production Example 5 was used instead of the aqueous dispersion of the particulate polymer 1 having a core-shell structure obtained in Production Example 1, to obtain an adhesive composition 5.

[0189] Example 17 In the production of the laminate of Example 1, the adhesive composition to be applied to the "region S where the adhesive material is densely applied" and the "region T where the adhesive material is sparsely applied" was changed from adhesive composition 1 prepared in Production Example 1 to adhesive composition 6 prepared as follows. An adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1, except that Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 4. <Preparation of Adhesive Layer Composition 6> In preparing the adhesive layer composition of Example 1, the same procedure as in Example 1 was repeated except that the aqueous dispersion of the particulate polymer 6 having a core-shell structure obtained in Production Example 6 was used instead of the aqueous dispersion of the particulate polymer 1 having a core-shell structure obtained in Production Example 1, to obtain an adhesive composition 6.

[0190] (Comparative Example 1) As the coaters 51 to 54, gravure coaters were used instead of inkjet coaters, and the adhesive composition 1 was applied to the entire bonding surface, so that the coverage of the adhesive material on the entire bonding surface was 90% and the basis weight of the adhesive material was 0.220 g / m 2 Except for this, an adhesive material, an adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 1. Then, various evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0191] (Comparative Example 2) In the production of the laminate of Example 2, the area of ​​the "region S where the adhesive material is densely applied" was changed from 10% to 100% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "region T where the adhesive material is sparsely applied" was changed from 90% to 0% of the area of ​​the bonding surfaces X and Y. Except for this, the adhesive composition, the negative electrode raw sheet, the positive electrode raw sheet, the separator raw sheet, the laminate, and the secondary battery were produced and prepared in the same manner as in Example 2. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0192] (Comparative Example 3) In the production of the laminate of Example 2, the area of ​​the "region S where the adhesive material is densely applied" was changed from 10% to 0% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "region T where the adhesive material is sparsely applied" was changed from 90% to 100% of the area of ​​the bonding surfaces X and Y. Except for this, an adhesive composition, a negative electrode raw sheet, a positive electrode raw sheet, a separator raw sheet, a laminate, and a secondary battery were produced and prepared in the same manner as in Example 2. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0193] In addition, in Tables 1 to 3, "MMA" indicates methyl methacrylate, "BA" indicates butyl acrylate, "2EHA" indicates 2-ethylhexyl acrylate, "AN" indicates acrylonitrile, "St" indicates styrene, "MAA" indicates methacrylic acid, "AA" indicates acrylic acid, "AGE" indicates allyl glycidyl ether, "AMA" indicates allyl methacrylate; "EDMA" refers to ethylene glycol dimethacrylate. Also, in Table 2, "PVdF-HFP" refers to vinylidene fluoride-hexafluoropropylene copolymer.

[0194] [Table 1]

[0195] [Table 2]

[0196] [Table 3]

[0197] [Table 4]

[0198] Tables 2, 3, and 4 show that in the secondary batteries of Examples 1 to 17, which have a laminate formed by stacking a positive electrode, a separator, and a negative electrode in this order, and in which, on surface Z, which is at least one of the bonding surface X between the positive electrode and the separator and the bonding surface Y between the negative electrode and the separator, a rectangular region P2 having a pair of opposite sides formed by the connection edge of the negative electrode tab and a line segment located a predetermined distance from the connection edge, has a resistance A2 per unit area greater than the resistance B2 per unit area of ​​a region Q2 other than region P2, lithium deposition on the negative electrode surface during charging is suppressed. On the other hand, in Comparative Examples 1 to 3, in which the resistance A2 per unit area of ​​the region P2 is not greater than the resistance B2 per unit area of ​​the region Q2 other than the region P2, it can be seen that the secondary battery is inferior in terms of suppressing lithium deposition on the negative electrode surface during charging. [Industrial Applicability]

[0199] According to the present invention, it is possible to provide a secondary battery in which metal deposition on the electrode surface during charging is suppressed. [Explanation of symbols]

[0200] 10 First separator 10A First separator roll 20 negative electrode 20A negative electrode material 21 Negative electrode current collector 22,23 Negative electrode composite layer 24 First edge 25 Second edge 26 Third edge 27 Fourth edge 28 Negative electrode tab 30 Second separator 30A Second separator roll 40 positive electrode 41 Positive electrode current collector 42, 43 Positive electrode composite layer 44 Positive electrode tab 50 droplets 51~54 Coating machine (nozzle head) 55 nozzles 60 Base material 61,62 Pressure roller 70 cutting machine 91 Conveyor roller 92 Heat Roller Z plane P1 Positive electrode tab peripheral area P2 Negative electrode tab peripheral area L1, L2 length of connecting edge S: Area where adhesive material is applied densely T Area where adhesive material is applied loosely r the radius of the dot x,y distance between dot centers l Line width of the coated area s Spacing between coated areas (line width of uncoated areas) 100,100A laminate 200 Superposition 300 Particulate polymer 310 Core 310S Core outer surface 320 Shell part

Claims

1. A secondary battery having a laminate formed by stacking a positive electrode, a separator, and a negative electrode in this order, at least one of a bonding surface X between the positive electrode and the separator and a bonding surface Y between the negative electrode and the separator is designated as a surface Z; When the length of either the positive electrode tab connected to the positive electrode or the negative electrode tab connected to the negative electrode is L, a resistance A per unit area of ​​a rectangular region P of the surface Z, the region P having a pair of opposite sides formed by the connecting side and a line segment at a distance of 0.3L from the connecting side, is greater than a resistance B per unit area of ​​a region Q other than the region P; An adhesive material is present on the surface Z, The adhesive material comprises a particulate polymer having a core-shell structure in which the glass transition temperature of the core polymer is −30° C. or higher and 100° C. or lower and the glass transition temperature of the shell polymer is 70° C. or higher and 140° C. or lower, or a particulate polymer not having a core-shell structure in which the glass transition temperature is −40° C. or higher and 0° C. or lower.

2. The secondary battery according to claim 1 , wherein a coverage rate E of the adhesive material in the region P of the surface Z is greater than a coverage rate F of the adhesive material in the region Q of the surface Z.

3. The secondary battery according to claim 2 , wherein the coverage E is 1.3% or more and 30% or less.

4. The secondary battery according to claim 2 or 3, wherein the coverage F is equal to or greater than 0.5% and less than 0.4×E%.

5. 5. The secondary battery according to claim 1, wherein the adhesive material contains the particulate polymer having the core-shell structure.

6. A method for manufacturing a secondary battery according to any one of claims 1 to 5, comprising: applying an adhesive material to a surface Z, which is at least one of a bonding surface X between the positive electrode and the separator and a bonding surface Y between the negative electrode and the separator; When the length of either the positive electrode tab connected to the positive electrode or the negative electrode tab connected to the negative electrode is L, a coverage rate E of the adhesive material in a rectangular region P of the surface Z, the region P having a pair of opposite sides formed by the connecting side and a line segment at a distance of 0.3L from the connecting side, is greater than a coverage rate F of the adhesive material in a region Q other than the region P; The adhesive material comprises a particulate polymer having a core-shell structure in which the glass transition temperature of the core polymer is −30° C. or higher and 100° C. or lower and the glass transition temperature of the shell polymer is 70° C. or higher and 140° C. or lower, or a particulate polymer not having a core-shell structure in which the glass transition temperature is −40° C. or higher and 0° C. or lower.

7. The method for producing a secondary battery according to claim 6 , wherein the coverage E is 1.3% or more and 30% or less.

8. The method for producing a secondary battery according to claim 6 or 7, wherein the coverage F is 0.5% or more and less than 0.4×E%.

9. The method for producing a secondary battery according to any one of claims 6 to 8, wherein the adhesive material contains the particulate polymer having the core-shell structure.