Secondary battery and method for manufacturing the same

Abstract

The secondary battery of the present application has a laminate in which a positive electrode, a separator, and a negative electrode are stacked in this order. At least either of a bonding surface X of the positive electrode to the separator and a bonding surface Y of the negative electrode to the separator is a surface Z, the resistance per unit area A of a central region P having a shape similar to that of the surface Z, a center at the same position as the center of the surface Z, and an area of 10% of the area of the surface Z is larger than the resistance per unit area B of a region Q other than the central region P in the surface Z.

Description

Technical Field

[0001] This invention relates to a secondary battery and its manufacturing method. Background Technology

[0002] Lithium-ion batteries and other rechargeable batteries are used in a wide range of applications due to their small size, light weight, high energy density, and ability to be repeatedly charged and discharged. Furthermore, rechargeable batteries typically include battery components such as a positive electrode, a negative electrode, and a spacer to isolate the positive and negative electrodes and prevent short circuits between them.

[0003] Here, as for the structure of secondary batteries, there are known stacked types, in which positive electrodes, spacers, and negative electrodes are alternately stacked, and wound types, in which long strips of positive electrodes, spacers, and negative electrodes are overlapped and rolled into concentric circles. Among these, stacked secondary batteries have attracted attention in recent years from the viewpoint of superior energy density, safety, quality, and durability.

[0004] Furthermore, in the manufacture of secondary batteries, for example, battery components with adhesive materials on their surfaces are manufactured, and these battery components are bonded to other battery components. Moreover, battery components with adhesive materials on their surfaces can be manufactured by applying an adhesive composition (slurry for secondary batteries) formed by dispersing and / or dissolving an adhesive polymer (adhesive material) in a solvent onto the surface of the battery component, and then drying it (see, for example, Patent Document 1).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent document 1: Japanese Patent Application Publication No. 2017-27945. Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In large secondary batteries used in vehicles, the battery heats up during charging and discharging, resulting in localized high-temperature areas within the battery. Furthermore, it is generally known that lithium-ion batteries are prone to degradation and shortened lifespan at high temperatures. Therefore, due to uneven temperature distribution and localized degradation within the battery, the overall battery lifespan deteriorates, thus requiring the elimination of internal temperature unevenness (hereinafter sometimes referred to as "cycle characteristics" in relation to lifespan).

[0010] However, in the existing secondary batteries mentioned above, there is room for improvement in cycle characteristics due to uneven temperature distribution inside the battery.

[0011] Therefore, the object of the present invention is to provide a secondary battery that eliminates temperature unevenness inside the battery and has excellent cycle characteristics.

[0012] Solution for solving the problem

[0013] To achieve the aforementioned objective, the inventors conducted in-depth research. They then discovered that by using at least one of the contact surfaces X (positive electrode and spacer) and Y (negative electrode and spacer) as surface Z, the resistance A per unit area of ​​the central region P is made greater than the resistance B per unit area of ​​the region Q (excluding the central region P) within surface Z. The central region P has a shape similar to that of surface Z, a center at the same position as the center of surface Z, and a predetermined area. This improves the cycle characteristics of the secondary battery, thus completing the present invention.

[0014] In other words, the object of the present invention is to advantageously solve the above-mentioned problems. The secondary battery of the present invention is characterized by having a stacked body in which a positive electrode, a spacer, and a negative electrode are stacked in sequence, with at least one of the contact surface X of the positive electrode and the spacer and the contact surface Y of the negative electrode and the spacer as surface Z. The resistance A per unit area of ​​the central region P is greater than the resistance B per unit area of ​​the region Q of surface Z excluding the central region P. The central region P has a shape similar to that of surface Z, has a center at the same position as the center of surface Z, and has an area of ​​10% of the area of ​​surface Z. In this way, by making the resistance A per unit area of ​​the central region P greater than the resistance B per unit area of ​​the region Q of surface Z excluding the central region P, and by making the central region P have a shape similar to that of surface Z, have a center at the same position as the center of surface Z, and have the aforementioned specified area, the cycle characteristics of the secondary battery can be improved.

[0015] Furthermore, in this invention, "center of a surface or region" means "centroid of a surface or region". For example, when the shape of the surface or region is any of a square, rectangle, parallelogram, or rhombus, "center of a surface or region" ("centroid of a surface or region") is "the intersection of the diagonals"; when the shape of the surface or region is a triangle, "center of a surface or region" ("centroid of a surface or region") is "the intersection of the medians"; and when the shape of the surface or region is a circle, "center of a surface or region" ("centroid of a surface or region") is "the center of the circle".

[0016] Furthermore, in this invention, the resistance A per unit area of ​​the central region P and the resistance B per unit area of ​​the region Q in the surface Z other than the central region P can be measured by the method described in the embodiments of this specification.

[0017] In this invention, the secondary battery preferably has an adhesive material present on the surface Z, and the coverage rate E of the adhesive material in the central region P of the surface Z is greater than the coverage rate F of the adhesive material in the region Q of the surface Z excluding the central region P. If the coverage rate E of the adhesive material in the central region P of the surface Z is greater than the coverage rate F of the adhesive material in the region Q of the surface Z excluding the central region P, the cycle characteristics of the secondary battery can be further improved.

[0018] Furthermore, the secondary battery of the present invention preferably has a coverage rate E of 1.1% or more and 30% or less. If the coverage rate E of the adhesive material in the central region P of surface Z is within the above-mentioned specified range, the good output characteristics of the secondary battery can be maintained, and the cycle characteristics of the secondary battery can be further improved. In addition, if the coverage rate E of the adhesive material in the central region P of surface Z is within the above-mentioned specified range, the adhesion between the electrode and the spacer can be sufficiently ensured, and the secondary battery can fully exert its excellent output characteristics.

[0019] Furthermore, the secondary battery of the present invention preferably has a coverage ratio F of 0.3% or more and less than 0.4 × E. If the coverage ratio F of the adhesive material in region Q of surface Z, excluding the central region P, is within the above-mentioned specified range, the adhesion between the electrode and the spacer can be sufficiently ensured, and the secondary battery can fully exert its excellent output characteristics. In addition, if the coverage ratio F of the adhesive material in region Q of surface Z, excluding the central region P, is within the above-mentioned specified range, the cycle characteristics of the secondary battery can be further improved.

[0020] Furthermore, the secondary battery of the present invention preferably has an adhesive material present on the aforementioned surface Z, and the coverage of the adhesive material on surface Z gradually decreases from the center of surface Z towards the periphery of surface Z. If the coverage of the adhesive material on surface Z gradually decreases from the center of surface Z towards the periphery of surface Z, the cycle characteristics of the secondary battery can be further improved.

[0021] Furthermore, the secondary battery of the present invention preferably has an adhesive material on the Z-side, the adhesive material comprising a particulate polymer having a core-shell structure, the core-shell structure having a core and a shell portion partially covering the outer surface of the core. If a particulate polymer having a core-shell structure, a core and a shell portion partially covering the outer surface of the core, is used as the adhesive material, the adhesion between the electrode and the spacer can be sufficiently ensured, and the secondary battery can exhibit excellent output characteristics.

[0022] Furthermore, the object of the present invention is to advantageously solve the above-mentioned problems. The method for manufacturing a secondary battery according to the present invention is characterized by being a method for manufacturing a secondary battery having a positive electrode, a spacer, and a negative electrode stacked sequentially, comprising a step of coating an adhesive material onto surface Z, wherein surface Z is at least one of the bonding surface X of the positive electrode and the spacer and the bonding surface Y of the negative electrode and the spacer; the coverage rate E of the adhesive material in the central region P is greater than the coverage rate F of the adhesive material in the region Q of surface Z excluding the central region P; the central region P has a shape similar to that of surface Z, has a center at the same position as the center of surface Z, and has an area of ​​10% of the area of ​​surface Z. Thus, according to the above-described method for manufacturing a secondary battery according to the present invention, a secondary battery with excellent cycle characteristics can be obtained.

[0023] In this invention, the coating rate E is preferably 1.1% or more and 30% or less in the manufacturing method of the secondary battery. If the coating rate E of the adhesive material in the central region P of surface Z is within the above-mentioned range, the cycle characteristics of the manufactured secondary battery can be further improved. Furthermore, if the coating rate E of the adhesive material in the central region P of surface Z is within the above-mentioned range, the adhesion between the electrode and the spacer can be sufficiently ensured, and the manufactured secondary battery can fully utilize its excellent output characteristics.

[0024] Furthermore, in the manufacturing method of the secondary battery of the present invention, the aforementioned coverage ratio F is preferably 0.3% or more and less than 0.4 × E. If the coverage ratio F of the adhesive material in region Q of surface Z, excluding the central region P, is within the aforementioned specified range, the adhesion between the electrode and the spacer can be sufficiently ensured, and the manufactured secondary battery can fully exhibit excellent output characteristics. Furthermore, if the coverage ratio F of the adhesive material in region Q of surface Z, excluding the central region P, is within the aforementioned specified range, the cycle characteristics of the manufactured secondary battery can be further improved.

[0025] Furthermore, in the manufacturing method of the secondary battery of the present invention, it is preferable that the coverage of the adhesive material in the aforementioned surface Z gradually decreases from the center of surface Z towards the periphery of surface Z. If the coverage of the adhesive material in surface Z gradually decreases from the center of surface Z towards the periphery of surface Z, the cycle characteristics of the manufactured secondary battery can be further improved.

[0026] Furthermore, the manufacturing method of the secondary battery of the present invention is characterized in that the adhesive material comprises a particulate polymer having a core-shell structure, the core-shell structure having a core and a shell portion partially covering the outer surface of the core. By using a particulate polymer having a core-shell structure with a core and a shell portion partially covering the outer surface of the core as the adhesive material, the adhesion between the electrode and the spacer can be sufficiently ensured, and the manufactured secondary battery can exhibit excellent output characteristics.

[0027] Invention Effects

[0028] According to the present invention, a secondary battery with excellent cycle characteristics can be provided. Attached Figure Description

[0029] Figure 1 (a) is a front view showing an example of the structure of the laminate in the secondary battery of the present invention. Figure 1 (b) is for explanation Figure 1 (a) is a top view showing the positional relationship between the negative and positive electrodes of the laminate.

[0030] Figure 2 A front view showing an example of the structure of an overlapped body obtained by overlapping the laminates in the secondary battery of the present invention.

[0031] Figure 3 A front view illustrating the structure of another example of a stack in a secondary battery according to the present invention.

[0032] Figure 4 This is an explanatory diagram illustrating the central region P and other regions Q in plane Z.

[0033] Figure 5 An illustrative diagram showing an example of a coating pattern for an adhesive material.

[0034] Figure 6 An illustrative diagram showing another example of a coating pattern for an adhesive material.

[0035] Figure 7 This is an illustrative diagram showing an example of a method for coating adhesive material onto the Z-side surface.

[0036] Figure 8 A cross-sectional view illustrating an example structure of a particulate polymer.

[0037] Figure 9 An illustrative diagram showing an example of the manufacturing process of the laminate in the secondary battery of the present invention.

[0038] Figure 10 To show Figure 9An illustrative diagram of an example of a coating machine (nozzle head).

[0039] Figure 11 Explanatory diagrams illustrating the manufacturing process of the laminates in the embodiments and comparative examples. Detailed Implementation

[0040] Hereinafter, the secondary battery and its manufacturing method according to the present invention will be described with reference to the accompanying drawings. Furthermore, for ease of understanding, the dimensions of some components are shown enlarged or reduced in the accompanying drawings.

[0041] (Secondary battery)

[0042] The secondary battery of the present invention has at least a defined laminate and, if necessary, an electrolyte and other components. Furthermore, the secondary battery of the present invention can be manufactured using, for example, the manufacturing method of the secondary battery of the present invention.

[0043] <Layered Body>

[0044] The secondary battery of the present invention has a stacked body consisting of a positive electrode, a spacer, and a negative electrode stacked in sequence.

[0045] Here, the stacked body in the secondary battery of the present invention has, for example... Figure 1 The structure shown, or Figure 3 The structure shown. Furthermore, the laminate can be arranged according to, for example... Figure 2 The overlapping bodies 200 are formed by overlapping as shown, and are used in stacked secondary batteries, etc.

[0046] like Figure 1 or Figure 3 As shown, the laminate 100, 100A has: a negative electrode 20, a first spacer 10 attached to one surface of the negative electrode, a positive electrode 40 attached to the surface of the first spacer 10 opposite to the side of the negative electrode 20, and a second spacer 30 attached to the other surface of the negative electrode 20 or the surface of the positive electrode 40 opposite to the side of the first spacer 10.

[0047] In addition, such as Figure 1 As shown in (b), the size of the positive electrode 40 in the laminate 100, 100A when viewed from above is smaller than the size of the negative electrode 20, the first spacer 10, and the second spacer 30 when viewed from above. Specifically, the negative electrode 20 of the laminate 100, 100A has a first end edge 24 and a second end edge 25 facing each other in a direction orthogonal to the lamination direction when viewed from the lamination direction. The positive electrode 40 is located between the first end edge 24 and the second end edge 25. In addition, the first end edge 24 and the second end edge 25 are generally the end edges corresponding to the cutting positions when the negative electrode 20 is made by cutting strips of negative electrode raw material.

[0048] Here, in Figure 1 (a) shows a front view of a stack 100 having: a negative electrode 20, and a component attached to the negative electrode 20 (in... Figure 1 The first spacer 10 on the surface of the middle (top) and the side attached to the first spacer 10 opposite to the negative electrode 20 side (in) Figure 1 The positive electrode 40 (located on the upper side) and the second spacer 30 are attached to the other surface of the negative electrode 20. In this example, the first spacer 10, negative electrode 20, second spacer 30, and positive electrode 40 are rectangular in top view. Furthermore, the negative electrode 20 has a structure in which negative electrode composite material layers 22 and 23 containing negative electrode active material are formed on both sides of the negative electrode current collector 21, and the positive electrode 40 has a structure in which positive electrode composite material layers 42 and 43 containing positive electrode active material are formed on both sides of the positive electrode current collector 41. Moreover, in top view, the size of the positive electrode 40 is smaller than the size of the negative electrode 20, the first spacer 10, and the second spacer 30, such as... Figure 1 As shown in (b) from a top view, the positional relationship between the negative electrode 20 and the positive electrode 40 is such that the positive electrode 40 is located in a direction orthogonal to the stacking direction of the negative electrode 20 (in... Figure 1 In (b), the first end edge 24 and the second end edge 25 facing each other in the left-right direction, and the part that is orthogonal to the first end edge 24 and the second end edge 25 and in Figure 1 Between the third end edge 26 and the fourth end edge 27 extending in the left and right directions in (b).

[0049] In addition, Figure 3 In the laminate 100A shown in the front view, the second spacer 30 is attached to the positive electrode 40 on the side opposite to the first spacer 10 (in... Figure 3 The surface of the upper side (in the middle) replaces the other surface of the negative electrode 20, and in addition, it has the same... Figure 1 The same structure as the laminate 100 shown.

[0050] Furthermore, the stacked structure of the secondary battery of the present invention is not limited to... Figure 1 and Figure 3 The example shown illustrates this. For instance, when viewed from above, the dimensions of the first spacer 10 and the second spacer 30 can also be larger than the dimensions of the negative electrode 20. If a stacked structure is used in which the first spacer 10 and the second spacer 30 are larger than the negative electrode 20, the safety of the secondary battery can be further improved.

[0051] <<Z side, central area P, other areas Q>>

[0052] The following uses Figure 4 Let's now describe the central region P in the Z region and the regions Q (hereinafter sometimes referred to as "other regions Q") excluding the central region P.

[0053] Here, surface Z is at least one of the contact surface X between the negative electrode 20 and the first spacer 10 and the contact surface Y between the positive electrode 40 and the first spacer 10.

[0054] like Figure 4 As shown, the central region P is a region that has a center (centroid) at the same location as the center (centroid) R (the intersection of the diagonals of the rectangle) of surface Z, has a shape similar to that of surface Z (rectangle), and has an area of ​​10% of the area of ​​surface Z. Furthermore, the other regions Q are all regions of surface Z except for the central region P, and have an area of ​​90% of the area of ​​surface Z.

[0055] Furthermore, the secondary battery of the present invention is characterized in that the resistance A per unit area of ​​the central region P is greater than the resistance B per unit area of ​​the other regions Q. In this way, by making the resistance A per unit area of ​​the central region P greater than the resistance B per unit area of ​​the other regions Q, the secondary battery can exhibit excellent cycle characteristics.

[0056] Here, the reason why the secondary battery can exhibit excellent cycle characteristics by making the resistance A per unit area of ​​the central region P greater than the resistance B per unit area of ​​other regions Q is still unclear, but the following is a conjecture.

[0057] First, in a secondary battery, surface Z heats up during charging and discharging due to the flow of current. In existing secondary batteries where the resistance A per unit area of ​​the central region P is less than or equal to the resistance B per unit area of ​​other regions Q, the central region P heats up at a rate equal to or greater than that of the other regions Q. Furthermore, other regions Q near the ends of surface Z can easily release heat, but the central region P, farther from the ends of surface Z, has difficulty releasing heat. Therefore, in the aforementioned existing secondary batteries, the central region P experiences higher temperatures compared to other regions Q due to heat storage, resulting in temperature unevenness within the battery and a decrease in the cycle characteristics of the secondary battery.

[0058] In contrast, in the secondary battery of the present invention, by making the resistance A per unit area of ​​the central region P greater than the resistance B per unit area of ​​other regions Q, the current density in the central region P during charging and discharging can be reduced. This reduces the heat generation in the central region P. Therefore, it can be deduced that since the temperature rise caused by heat storage in the central region P can be suppressed, the secondary battery can exhibit excellent cycle characteristics by reducing the temperature unevenness between the central region P and other regions Q.

[0059] In addition, "the end of surface Z" refers to the area of ​​surface Z other than the central region P'', in the case that the central region P'' is a region that has a center at the same position as the center R of surface Z, has a similar shape to surface Z, and has an area that is 90% of the area of ​​surface Z.

[0060] Furthermore, the ratio (A / B) of the resistance A per unit area of ​​the central region P to the resistance B per unit area of ​​the other region Q needs to be greater than 1, preferably greater than 1.005, more preferably greater than 1.01, preferably less than 2, and more preferably less than 1.5. When the ratio (A / B) of the resistance A per unit area of ​​the central region P to the resistance B per unit area of ​​the other region Q is greater than 1, the cycle characteristics of the secondary battery can be sufficiently improved. On the other hand, if the ratio (A / B) of the resistance A per unit area of ​​the central region P to the resistance B per unit area of ​​the other region Q is less than 2, the output characteristics of the secondary battery can be improved.

[0061] In addition, the resistance A per unit area of ​​the central region P and the resistance B per unit area of ​​the other regions Q can be adjusted according to the coverage of the adhesive material in each region, the type of polymer used as the adhesive material, etc.

[0062] [Adhesive Material]

[0063] Here, adhesive material is typically present in surfaces Z (coating surfaces X and Y). This adhesive material is used to bond the electrodes (positive or negative) to the spacers in surfaces X and Y. Further details regarding the adhesive material will be described later.

[0064] - Coating method for adhesive materials-

[0065] The adhesive material can be supplied to the bonding surfaces X and Y in any state, such as solid, molten, dissolved in a solvent, or dispersed in a solvent. Preferably, the adhesive material is supplied in a state dissolved in a solvent or dispersed in a solvent, and more preferably, it is supplied in a state dispersed in a solvent.

[0066] Furthermore, when the adhesive material is supplied to the bonding surfaces X and Y in a state of being dissolved in or dispersed in a solvent, that is, when an adhesive composition containing the adhesive material and the solvent is supplied to the bonding surfaces, there are no particular limitations on the solvent used in the adhesive composition, and examples such as water, organic solvents, and mixtures thereof can be used. Additionally, there are no particular limitations on the organic solvent, and examples include: cyclic aliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl 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.

[0067] In the above, from the viewpoint of efficiently manufacturing laminates, a solvent comprising at least one of water and alcohol is preferred as the solvent.

[0068] In addition, at least a portion of the solvents mentioned above can be removed during the manufacturing process of the laminate by means of drying or the like.

[0069] In addition, the coating machine described later was used ( Figure 9 and Figure 10 The adhesive material of (51-54) can be coated using known coating methods such as inkjet, spray, drop coating, gravure coating, and screen printing. Among these, from the viewpoint that the amount and range of the adhesive material can be easily adjusted, inkjet coating is preferred.

[0070] Furthermore, 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 prescribed pattern, such as stripes, dots, or a grid. Moreover, 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 dotted pattern.

[0071] Here, the diameter of the dots in the adhesive material arranged in a dotted pattern is preferably 10 μm or more, more preferably 20 μm or more, more preferably 100 μm or less, and more preferably 80 μm or less. If the diameter of the dots in the adhesive material is at or above the lower limit mentioned above, the adhesion between the electrode and the spacer can be improved. On the other hand, if the diameter of the dots in the adhesive material is at or below the upper limit mentioned above, the reduction in the output characteristics of the secondary battery can be suppressed.

[0072] The following describes the case where adhesive material is applied to surface Z in such a way that there are two regions: a region S in which adhesive material is densely applied and a region T in which adhesive material is sparsely applied.

[0073] Here, the coverage rate of adhesive material in the "region S in which adhesive material is densely coated" is greater than the coverage rate of adhesive material in the "region T in which adhesive material is sparsely coated".

[0074] In addition, in this specification, the “coverage rate of adhesive material” in a certain surface or area refers to the proportion of the area of ​​the part covered by adhesive material in the total area of ​​the surface or area [(area of ​​the part covered by adhesive material / total area of ​​the surface or area) × 100 (%)].

[0075] Furthermore, in this specification, when an adhesive composition containing adhesive material and solvent is supplied to the bonding surface, "adhesive material" in "coverage of adhesive material" refers to the state in which the adhesive layer composition has had the solvent removed by drying or the like.

[0076] The shape of the "region S in which the adhesive material is densely coated" is not particularly limited and can be appropriately set within the range of achieving the desired effect of the present invention. That is, the "region S in which the adhesive material is densely coated" can have any shape as long as the resistance A per unit area of ​​the central region P is greater than the resistance B per unit area of ​​the other regions Q.

[0077] In addition, the "region T with sparsely coated adhesive material" refers to all regions in surface Z except for the "region S with densely coated adhesive material".

[0078] Furthermore, from the viewpoint of further improving the cycle characteristics of the secondary battery, it is preferable to set the shape of the "region S in which the adhesive material is densely coated" in such a way that the coverage rate E of the adhesive material in the central region P is greater than the coverage rate F of the adhesive material in other regions Q.

[0079] For example, from the viewpoint of further improving the cycle characteristics of secondary batteries, the "region S in which the adhesive material is densely coated" preferably includes the center of the surface Z, and more preferably has a center at the same position as the center of the surface Z.

[0080] Furthermore, the shape of the "region S in which the adhesive material is densely coated" may or may not be similar to the shape of the surface Z. From the viewpoint of further improving the cycle characteristics of the secondary battery, a shape similar to the shape of the surface Z is preferred.

[0081] Furthermore, the area of ​​the "region S in which the adhesive material is densely coated" preferably accounts for 5% or more of the total area of ​​surface Z, more preferably 10% or more, more preferably 60% or less, more preferably 40% or less, and even more preferably 30% or less. If the area of ​​the "region S in which the adhesive material is densely coated" accounts for the total area of ​​surface Z within the above-mentioned range, the cycle characteristics of the secondary battery can be further improved. In addition, if the area of ​​the "region S in which the adhesive material is densely coated" accounts for the total area of ​​surface Z at or below the above-mentioned upper limit, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0082] Furthermore, the area of ​​the "region T with sparsely coated adhesive material" preferably accounts for 40% or more, more preferably 60% or more, even more preferably 70% or more, more preferably 95% or less, and more preferably 90% or less. If the area of ​​the "region T with sparsely coated adhesive material" accounts for the total area of ​​the Z area within the above-mentioned range, the cycle characteristics of the secondary battery can be further improved. Furthermore, if the area of ​​the "region T with sparsely coated adhesive material" accounts for the total area of ​​the Z area at or above the lower limit mentioned above, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0083] Furthermore, there is no particular limitation as long as the coverage rate J of the adhesive material in the "region S in which the adhesive material is densely coated" is greater than the coverage rate K of the adhesive material in the "region T in which the adhesive material is sparsely coated". Preferably, it is 1.1% or more, more preferably 3% or more, 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 in which the adhesive material is densely coated" is above or below the above lower limit, the cycle characteristics of the secondary battery can be further improved. In addition, if the coverage rate J of the adhesive material in the "region S in which the adhesive material is densely coated" is below or below the above upper limit, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0084] Furthermore, there are no particular limitations as long as the coverage rate K of the adhesive material in the "region T where the adhesive material is sparsely coated" is less than the coverage rate J of the adhesive material in the "region S where the adhesive material is densely coated". Preferably, it is 0.3% or more, more preferably 0.5% or more, and more preferably less than 0.4 × J%. If the coverage rate of the adhesive material in the "region T where the adhesive material is sparsely coated" is above the aforementioned lower limit, the adhesion between the electrode and the spacer can be sufficiently ensured. Furthermore, if the coverage rate K of the adhesive material in the "region T where the adhesive material is sparsely coated" is less than the aforementioned upper limit, the cycle characteristics of the secondary battery can be sufficiently improved.

[0085] Furthermore, the coverage rate of adhesive material in each of the regions "area S in which adhesive material is densely coated" and "area T in which adhesive material is sparsely coated" can be adjusted by changing the pattern of the arrangement of adhesive material in each region.

[0086] Specifically, in a certain area, when the adhesive material is arranged (coated) in a dotted pattern, the coverage of the adhesive material in that area can be adjusted by changing the radius of the dots and the distance between their centers.

[0087] For example, such as Figure 5 As shown, in a region where adhesive material is applied in a dotted pattern, and the dots are formed by two orthogonal directions at a certain interval, the coverage of the adhesive material can be obtained using the center-to-center distance (spacing) x and y of the dots, and the radius r of the dots, by the following formula (1).

[0088]

[0089] Furthermore, in a certain area, when the adhesive material is arranged (coated) in a striped pattern, the coverage rate of the adhesive material in that area can be adjusted by changing the line width of the coated portion and the spacing of the coated portion (the line width of the uncoated portion).

[0090] For example, such as Figure 6 As shown, in a region where the adhesive material is coated with a striped pattern with a line width of l for the coated portion and a spacing of s for the uncoated portion, the coverage rate of the adhesive material can be obtained by the following formula (2).

[0091]

[0092] Furthermore, the unit area weight of the adhesive material in the densely coated region S is preferably 0.02 g / m². 2 The above is preferably 0.8 g / m 2 The following is more preferably 0.35 g / m 2 The following applies: If the weight per unit area of ​​the adhesive material in the densely coated region S is above the lower limit mentioned above, the adhesion between the electrode and the spacer can be sufficiently ensured. Furthermore, if the weight per unit area of ​​the adhesive material in the densely coated region S is below the upper limit mentioned above, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0093] Furthermore, the unit area weight of the adhesive material in the sparsely coated region T is preferably 0.02 g / m². 2 The above, more preferably 0.03 g / m 2 The preferred value is 0.35 g / m³. 2 The following applies: If the weight per unit area of ​​the adhesive material in the sparsely coated region T is above the lower limit mentioned above, the adhesion between the electrode and the spacer can be sufficiently ensured. Furthermore, if the weight per unit area of ​​the adhesive material in the sparsely coated region T is below the upper limit mentioned above, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0094] Furthermore, in this specification, when the adhesive composition containing adhesive material and solvent is supplied to the bonding surface, the "adhesive material" in "weight per unit area of ​​adhesive material" refers to the adhesive material in a state where the solvent has been removed from the adhesive layer composition by drying or the like.

[0095] In addition, in each of the aforementioned "region S in which adhesive material is densely coated" and "region T in which adhesive material is sparsely coated", the adhesive material can be configured (coated) with the same pattern as a whole, or adhesive materials configured (coated) with multiple different patterns can be mixed together.

[0096] Furthermore, in each region, the pattern of the adhesive material coating can also gradually change along a fixed direction. For example, when the adhesive material is coated with a dotted pattern, the radius and center-to-center distance of the dots can gradually change along a fixed direction; similarly, when the adhesive material is coated with a striped pattern, the line width of the coated portion and the spacing between the coated portions (the line width of the uncoated portion) can gradually change along a fixed direction.

[0097] Here, the direction in which the pattern coated with adhesive material gradually changes is not particularly limited, as long as the desired effect of the present invention can be obtained.

[0098] For example, preferably in at least one of the "region S in which the adhesive material is densely coated" and the "region T in which the adhesive material is sparsely coated", the pattern of the adhesive material coating gradually changes along a direction from the center of surface Z towards the periphery of surface Z, so that when observing surface Z as a whole, the coverage of the adhesive material in surface Z gradually decreases from the center of surface Z towards the periphery of surface Z. If the coverage of the adhesive material gradually decreases from the center of surface Z towards the periphery of surface Z, the cycle characteristics of the secondary battery can be further improved.

[0099] Here, the case where the coverage of the adhesive material in plane Z gradually decreases from the center of plane Z towards the periphery of plane Z will be explained with reference to the accompanying drawings.

[0100] exist Figure 7 In the surface Z shown, there exists a region S (adhesive material coverage: G) densely coated with adhesive material. Furthermore, regions T1 (adhesive material coverage: H1), T2 (adhesive material coverage: H2), and T3 (adhesive material coverage: H3) sparsely coated with adhesive material each exist as part of the sparsely coated region T. Here, the adhesive material coverage in each region satisfies the relationship: G>H1>H2>H3. Moreover, region T3, with further sparse adhesive material coating, is located further inward than the periphery of surface Z and further outward than region T2, with more sparse adhesive material coating. Similarly, region T2, with further sparse adhesive material coating, is located further inward than region T3 and further outward than region T1, with more sparse adhesive material coating. Furthermore, the region T1 where the adhesive material is sparsely coated is located further inward than the region T2 where the adhesive material is even sparsely coated, and further outward than the region S where the adhesive material is densely coated. Additionally, the region S where the adhesive material is densely coated is located further inward than the region T1 where the adhesive material is sparsely coated. By coating the adhesive material onto surface Z as described above, the coverage of the adhesive material on surface Z can be made to gradually decrease from the center of surface Z towards the periphery of surface Z.

[0101] In addition, Figure 7 In the diagram, the outer periphery of each of the regions—S (densely coated with adhesive material), T1 (sparsely coated with adhesive material), and T2 (sparsely coated with adhesive material)—is elliptical in shape, but is not limited to this; it can also be a shape similar to, for example, the shape of surface Z. Furthermore, the outer periphery of each of the aforementioned regions may have a center at the same location as the center R of surface Z, or it may have a center at a different location than the center R of surface Z.

[0102] Furthermore, the aforementioned central region P may or may not correspond to the "region S in which adhesive material is densely applied". Therefore, within the central region P, there may be only a portion corresponding to the "region S in which adhesive material is densely applied", or there may be a mixture of portions corresponding to the "region S in which adhesive material is densely applied" and portions corresponding to the "region S in which adhesive material is sparsely applied".

[0103] Furthermore, the other regions Q mentioned above may or may not correspond to the "region T in which the adhesive material is sparsely coated". Therefore, within the other regions Q, there may be only a portion equivalent to the "region T in which the adhesive material is sparsely coated", or there may be a mixture of portions equivalent to the "region S in which the adhesive material is densely coated" and portions equivalent to the "region T in which the adhesive material is sparsely coated".

[0104] Here, in the case where a region U, which is either the central region P or any of the other regions Q, contains a portion equivalent to "region S with densely coated adhesive material" and a portion equivalent to "region T with sparsely coated adhesive material", the coverage of the adhesive material in region U can be obtained by the following formula (3).

[0105]

[0106] Furthermore, the coverage rate E of the adhesive material in the central region P is preferably greater than the coverage rate F of the adhesive material in other regions Q.

[0107] Specifically, the coverage rate E of the adhesive material in the central region P is preferably 1.1% or more, more preferably 1.4% or more, even 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 E of the adhesive material in the central region P is at or above the aforementioned lower limit, the cycle characteristics of the secondary battery can be further improved. On the other hand, if the coverage rate E of the adhesive material in the central region P is at or below the aforementioned upper limit, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0108] Furthermore, the coverage rate F of the adhesive material in other regions Q is preferably smaller than the coverage rate E of the adhesive material in the central region P.

[0109] Specifically, the coverage rate F of the adhesive material in other regions Q is preferably 0.3% or more, more preferably 0.5% or more, and preferably less than 0.4×E. If the coverage rate F of the adhesive material in other regions Q is at or above the aforementioned lower limit, the adhesion between the electrode and the spacer can be sufficiently ensured. On the other hand, if the coverage rate F of the adhesive material in other regions Q is less than the aforementioned upper limit, the cycle characteristics of the secondary battery can be further improved.

[0110] Furthermore, the ratio (E / F) of the coverage rate E of the adhesive material in the central region P to the coverage rate F of the adhesive material in other regions Q is preferably 1.6 or more, more preferably 2.0 or more, even more preferably 2.6 or more, preferably 16.0 or less, more preferably 10.0 or less, and even more preferably 8.0 or less. If the ratio (E / F) of the coverage rate E of the adhesive material in the central region P to the coverage rate F of the adhesive material in other regions Q is at or above the aforementioned lower limit, the cycle characteristics of the secondary battery can be further improved. On the other hand, if the ratio (E / F) of the coverage rate E of the adhesive material in the central region P to the coverage rate F of the adhesive material in other regions Q is at or below the aforementioned upper limit, both the adhesion strength between the electrode and the spacer and the output characteristics of the secondary battery can be balanced at a high level.

[0111] Furthermore, the unit area weight of the adhesive material in the central region P is preferably 0.02 g / m². 2 The above is preferably 0.8 g / m 2 The following is more preferably 0.35 g / m 2 The following applies: If the weight per unit area of ​​the adhesive material in the central region P is above the lower limit mentioned above, the adhesion between the electrode and the spacer can be sufficiently ensured. Furthermore, if the weight per unit area of ​​the adhesive material in the central region P is below the upper limit mentioned above, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0112] Furthermore, the unit area weight of the adhesive material in other regions Q is preferably 0.02 g / m². 2 The above, more preferably 0.03 g / m 2 The preferred value is 0.35 g / m³. 2 The following applies: If the weight per unit area of ​​the adhesive material in other regions Q is above the lower limit mentioned above, the adhesion between the electrode and the spacer can be sufficiently ensured. Furthermore, if the weight per unit area of ​​the adhesive material in other regions Q is below the upper limit mentioned above, the output characteristics of the secondary battery can be sufficiently high.

[0113] -Details of the adhesive materials-

[0114] Here, as an adhesive material, there are no particular limitations, as long as it does not hinder the battery reaction; any adhesive material applicable in the field of rechargeable batteries can be used. Among these, an adhesive material composed of a polymer is preferred. Furthermore, the adhesive material can consist of only one type of polymer, or it can consist of two or more types.

[0115] Polymers that can be used as adhesive materials are not particularly limited, but can include: fluorinated polymers such as polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP); conjugated diene polymers such as styrene-butadiene copolymer (SBR) and acrylonitrile-butadiene copolymer (NBR); hydrides of conjugated diene polymers; polymers containing alkyl methacrylate monomer units (acrylic polymers); polyvinyl alcohol (PVA) and other polyvinyl alcohol polymers.

[0116] Additionally, in this invention, "(meth)acrylic acid" means acrylic acid and / or methacrylic acid.

[0117] Furthermore, the shape of the adhesive material made of polymer is not particularly limited; it can be granular, non-granular, or a combination of granular and non-granular.

[0118] In addition, when the adhesive material made of polymer is a particulate polymer, the adhesive material of the particulate polymer can be particles with a single-phase structure formed by a single polymer, or particles with a heterogeneous structure formed by physically or chemically combining two or more polymers that are different from each other.

[0119] Here, specific examples of heterogeneous structures include: core-shell structures in which the central part (core) and outer shell (shell) of spherical particles are formed from different polymers; and side-by-side structures in which two or more polymers are placed side by side.

[0120] Furthermore, in this invention, the "core-shell structure" includes not only a structure in which the outer surface of the core is completely covered by the shell, but also, for example, Figure 8 The structure shown is one in which the outer surface of the core is partially covered by the shell.

[0121] Furthermore, in this invention, even when the outer surface of the core appears to be completely covered by the shell, if a hole is formed connecting the inside and outside of the shell, then the shell is a shell that partially covers the outer surface of the core. Therefore, for example, a particulate polymer having a shell with a pore connecting the outer surface of the shell (i.e., the circumferential surface of the particulate polymer) to the outer surface of the core is a particulate polymer in which the shell partially covers the outer surface of the core.

[0122] The swelling degree (hereinafter, sometimes simply referred to as "swelling degree") of the adhesive material in the electrolyte (a solution of LiPF6 dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate / diethyl carbonate = 3 / 7 by volume) is preferably 110% or more, preferably 1500% or less, more preferably 1300% or less, and particularly preferably 1000% or less. If the swelling degree of the adhesive material is below the above-mentioned upper limit, the permeability of the electrolyte to the center of the positive or negative electrode can be improved.

[0123] In addition, the degree of swelling of the adhesive material in the electrolyte can be determined by the method described in the examples of this specification.

[0124] --Particulate polymer--

[0125] Furthermore, particulate polymers are preferred as adhesive materials. Additionally, either particulate polymers with a core-shell structure or particulate polymers without a core-shell structure can be used as the particulate polymer; preferably, at least a particulate polymer with a core-shell structure is used, and more preferably, both particulate polymers with and without a core-shell structure are used.

[0126] Furthermore, when using both particulate polymers with and without core-shell structures, the mass ratio of the particulate polymers with and without core-shell structures in the adhesive material can be appropriately adjusted within a range that yields the desired effects of the present invention.

[0127] =Particulate polymers with a core-shell structure=

[0128] Core-shell structured particulate polymers function as adhesives in bonding materials used to bond battery components such as spacers and electrodes together. By using core-shell structured particulate polymers as adhesives, battery components can be firmly bonded together, enabling the secondary battery to exhibit excellent output characteristics.

[0129] Here, the particulate polymer has a core-shell structure, which has a core and a shell covering the outer surface of the core. The shell may cover the entire outer surface of the core, or it may partially cover the outer surface of the core. Furthermore, even if the outer surface of the core appears to be completely covered by the shell, if a hole is formed connecting the inside and outside of the shell, then the shell partially covers the outer surface of the core.

[0130] Figure 8 A cross-sectional structure of an example of a particulate polymer is shown. Figure 8In this process, the particulate polymer 300 has a core-shell structure, which includes a core portion 310 and a shell portion 320. Here, the core portion 310 is the portion of the particulate polymer 300 that is located inside the shell portion 320. Furthermore, the shell portion 320 is the portion that covers the outer surface 310S of the core portion 310, and is typically the outermost portion of the particulate polymer 300. Moreover, in... Figure 8 In the example, 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.

[0131] Furthermore, particulate polymers may have any constituent elements other than the core and shell described above, provided that the desired effect is not significantly impaired. Specifically, for example, a particulate polymer may also have a portion inside the core formed of a polymer different from the core. As a specific example, in the case of manufacturing particulate polymers using seed polymerization, the seed particles used may remain inside the core. However, from the viewpoint of significantly achieving the desired effect, particulate polymers preferably have only a core and a shell.

[0132] The glass transition temperature of the polymer in the core of the particulate polymer is preferably -30°C or higher, more preferably -20°C or higher, more 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 is -30°C or higher, the battery components can be more firmly bonded to each other using an adhesive material. On the other hand, if the glass transition temperature of the polymer in the core is 200°C or lower, the polymerization stability of the particulate polymer can be ensured.

[0133] In addition, the glass transition temperature of the polymer can be determined by the methods described in the examples of this specification.

[0134] Furthermore, the glass transition temperature of the polymer in the core can be adjusted by changing, for example, the type and ratio of monomers used to prepare the polymer in the core.

[0135] Examples of monomers used to prepare the polymer core 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; (meth)acrylate monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl methacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and cyclohexyl methacrylate; (meth)acrylamide monomers such as acrylamide and methacrylamide; (meth)acrylonitrile monomers such as acrylonitrile and methacrylonitrile; fluorinated (meth)acrylate monomers such as 2-(perfluorohexyl)ethyl methacrylate and 2-(perfluorobutyl)ethyl acrylate; maleimide; and maleimide derivatives such as phenylmaleimide. Furthermore, these can be used alone or in combination of two or more in any ratio.

[0136] Additionally, in this invention, (meth)acrylic acid means acrylic acid and / or methacrylic acid, and (meth)acrylonitrile means acrylonitrile and / or methacrylonitrile.

[0137] Among these monomers, the monomers used as the polymer for preparing the core are preferably at least (meth)acrylate monomers, more preferably a combination of (meth)acrylate monomers and aromatic vinyl monomers, or a combination of (meth)acrylate monomers and (meth)acrylonitrile monomers, particularly preferably a combination of (meth)acrylate monomers and aromatic vinyl monomers, from the viewpoint of further firmly bonding the battery components to each other via adhesive materials. That is, the polymer of the core preferably contains at least (meth)acrylate monomer units, more preferably (meth)acrylate monomer units and aromatic vinyl monomer units, or (meth)acrylate monomer units and (meth)acrylonitrile monomer units, and even more preferably (meth)acrylate monomer units and aromatic vinyl monomer units.

[0138] In addition, in this invention, "containing monomer units" means "the polymer obtained using the monomer contains repeating units from the monomer".

[0139] Furthermore, in this invention, "(meth)acrylate monomer" refers to a monofunctional (meth)acrylate monomer having only one polymerization reactive group.

[0140] Furthermore, from the viewpoint of further firmly bonding the battery components together via adhesive materials, with all repeating units (all monomer units) contained in the polymer of the core as 100% by mass, the proportion of (meth)acrylate monomer units in the polymer of the core is preferably 5% by mass or more, more preferably 10% by mass or more, particularly preferably 20% by mass or more, preferably 80% by mass or less, and more preferably 70% by mass or less.

[0141] Furthermore, when the polymer in the core contains (meth)acrylate monomer units and aromatic vinyl monomer units, from the viewpoint of further firmly bonding the battery components to each other via adhesive materials, the proportion of aromatic vinyl monomer units in the polymer in the core is preferably 15% by mass or more, more preferably 20% by mass or more, particularly preferably 25% by mass or more, preferably 95% by mass or less, more preferably 80% by mass or less, and particularly preferably 65% ​​by mass or less, with all repeating units (all monomer units) contained in the polymer in the core comprising 100% by mass.

[0142] Furthermore, when the polymer in the core contains (meth)acrylate monomer units and (meth)acrylonitrile monomer units, from the viewpoint of further firmly bonding the battery components to each other via an adhesive material, with all repeating units (all monomer units) contained in the polymer in the core as 100% by mass, the proportion of (meth)acrylonitrile monomer units in the polymer in the core is preferably 5% by mass or more, more preferably 10% by mass or more, particularly preferably 15% by mass or more, preferably 30% by mass or less, and more preferably 25% by mass or less.

[0143] Furthermore, the polymer in the core can contain monomer units with acid groups. Examples of monomers containing acid groups include monomers with acid groups, such as monomers with carboxylic acid groups, monomers with sulfonic acid groups, and monomers with phosphate groups.

[0144] Furthermore, examples of monomers containing a carboxylic acid group include monocarboxylic acids and dicarboxylic acids. Examples of monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid. Examples of dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid.

[0145] In addition, examples of monomers having sulfonic acid groups include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth)allyl sulfonic acid, ethyl (meth)acrylic acid-2-sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid.

[0146] Furthermore, examples of monomers with phosphate groups include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate.

[0147] Additionally, in this invention, (methyl)allyl means allyl and / or methylallyl, and (meth)acryloyl means acrylamide and / or methacryloyl.

[0148] Among these, monomers containing acid groups are preferred, especially those with carboxylic acid groups, particularly monocarboxylic acids, and more preferably (meth)acrylic acid.

[0149] In addition, acid-containing monomers can be used alone or in combination of two or more in any ratio.

[0150] Furthermore, with all repeating units (all monomer units) contained in the polymer of the core portion as 100% by mass, the proportion of acid-containing monomer units in the polymer of the core portion is preferably 0.1% by mass or more, more preferably 1% by mass or more, more preferably 15% by mass or less, and more preferably 10% by mass or less. By keeping the proportion of acid-containing monomer units within the above range, the dispersibility of the polymer of the core portion can be improved when preparing particulate polymers, and a shell portion that partially covers the outer surface of the core portion can be easily formed on the outer surface of the polymer of the core portion.

[0151] Furthermore, the polymer in the core preferably includes crosslinking monomer units in addition to the aforementioned monomer units. Crosslinking monomers are monomers that can form a crosslinked structure during or after polymerization by heating or irradiation with energy rays.

[0152] Examples of crosslinking monomers include, for instance, polyfunctional monomers having two or more polymerization-reactive groups. Examples of such polyfunctional monomers include: divinylbenzene, 1,3-butadiene, isoprene, allyl methacrylate, and other divinyl monomers; di(meth)acrylate monomers such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, 1,3-butanediol diacrylate; tri(meth)acrylate monomers such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; olefinically unsaturated monomers containing epoxy groups such as allyl glycidyl ether and glycidyl methacrylate; and γ-methacryloyloxypropyltrimethoxysilane. Among these, di(meth)acrylate monomers are more preferred. Furthermore, these monomers can be used alone or in combination of two or more in any ratio.

[0153] Furthermore, with all repeating units (all monomer units) contained in the polymer of the core portion as 100% by mass, the proportion of crosslinked monomer units in the polymer of the core portion is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, particularly preferably 0.4% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. By keeping the proportion of crosslinked monomer units within the above range, the battery components can be further and more firmly bonded to each other by the adhesive material.

[0154] The glass transition temperature of the polymer in the shell portion of the granular polymer is preferably 70°C or higher, more preferably 80°C or higher, particularly preferably 90°C or higher, 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 together using adhesive materials.

[0155] Furthermore, the glass transition temperature of the polymer in the shell can be adjusted by changing, for example, the type and proportion of monomers used to prepare the polymer in the shell.

[0156] Furthermore, from the viewpoint of maintaining the shape of the granular polymer after the battery components are bonded together and suppressing the increase of resistance, the glass transition temperature of the polymer in the shell is preferably 30°C or more higher than that of the polymer in the core, and more preferably 50°C or more higher.

[0157] Examples of monomers used as monomers for preparing the shell of a polymer include those similar to those used as monomers for manufacturing the core of a polymer. Furthermore, such monomers can be used alone or in combination of two or more in any ratio.

[0158] Among these monomers, from the viewpoint of further firmly bonding the battery components together via adhesive materials, aromatic vinyl monomers are preferably used as monomers for preparing the polymer of the casing. That is, the polymer of the casing preferably contains aromatic vinyl monomer units.

[0159] Furthermore, from the viewpoint of further firmly bonding the battery components together via adhesive materials, with all repeating units (all monomer units) contained in the polymer of the shell as 100% by mass, the proportion of aromatic vinyl monomer units in the polymer of the shell is preferably 85% by mass or more, preferably 90% by mass or more, particularly preferably 95% by mass or more, and preferably 99% by mass or less.

[0160] In addition to aromatic vinyl monomer units, the polymer in the shell can also contain acid-containing monomer units. Examples of acid-containing monomers include monomers with acid groups, such as monomers with carboxylic acid groups, monomers with sulfonic acid groups, and monomers with phosphate groups. Specifically, examples of acid-containing monomers include the same monomers that can be used to form the core.

[0161] Among these, monomers containing acid groups are preferred, those having carboxylic acid groups are preferred, monocarboxylic acids are more preferred, and (meth)acrylic acid is even more preferred.

[0162] In addition, acid-containing monomers can be used alone or in combination of two or more in any ratio.

[0163] Furthermore, with all repeating units (all monomer units) contained in the polymer of the shell portion as 100% by mass, the proportion of acid-containing monomer units in the polymer of the shell portion is preferably 0.1% by mass or more, preferably 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less. By keeping the proportion of acid-containing monomer units within the above range, the dispersibility of the particulate polymer can be improved, and the battery components can be more firmly bonded to each other by the adhesive material.

[0164] In the particulate polymer having a core-shell structure, the mass ratio of the polymer in the core to the polymer in the shell (core / shell) is preferably 5 / 5 or more, more preferably 6 / 4 or more, more preferably 9 / 1 or less, and more preferably 8 / 2 or less. If the mass ratio of the polymer in the core to the polymer in the shell (core / shell) is within the above-mentioned range, the battery components can be further firmly bonded to each other by an adhesive material.

[0165] Furthermore, the volume average particle size of the particulate polymer with a core-shell structure is preferably 100 nm or more, more preferably 300 nm or more, more preferably 1000 nm or less, more preferably 900 nm or less, even more preferably 800 nm or less, and even more preferably 700 nm or less. If the volume average particle size of the particulate polymer with a core-shell structure is within the above-mentioned range, the battery components can be further firmly bonded to each other by an adhesive material.

[0166] In addition, the volume average particle size of the particulate polymer can be determined by the method described in the examples of this specification.

[0167] Furthermore, the aforementioned particulate polymer with a core-shell structure can be prepared by, for example, using monomers of the polymer in the core and monomers of the polymer in the shell, and changing the ratio of these monomers over time. Specifically, the particulate polymer can be prepared by continuous multi-stage emulsion polymerization and multi-stage suspension polymerization, in which polymers in later stages sequentially coat polymers in earlier stages.

[0168] Therefore, the following is an example of obtaining a particulate polymer with the above-mentioned core-shell structure by multi-stage emulsion polymerization.

[0169] During polymerization, emulsifiers can typically include anionic surfactants such as sodium dodecylbenzenesulfonate and sodium dodecyl sulfate; nonionic surfactants such as polyoxyethylene nonylphenyl ether and sorbitol monolaurate; or cationic surfactants such as octadecylamine acetate. Furthermore, polymerization initiators can include peroxides such as tert-butylperoxide-2-ethylhexanoate, potassium persulfate, and cumene peroxide; and azo compounds such as 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)-propionamide) and 2,2'-azobis(2-amidinylpropane) hydrochloride.

[0170] Furthermore, as a polymerization step, firstly, the monomers forming the core and the emulsifier are mixed, and emulsion polymerization is performed in a single step to obtain a particulate polymer constituting the core. Then, in the presence of this particulate polymer constituting the core, the monomers forming the shell are polymerized, thereby obtaining the aforementioned particulate polymer with a core-shell structure.

[0171] In this case, when preparing a particulate polymer in which the outer surface of the core is partially covered by a shell, it is preferable to supply the monomers of the polymer forming the shell to the polymerization system in batches or continuously. By supplying the monomers of the polymer forming the shell to the polymerization system in batches or continuously, the polymer constituting the shell is formed into particulate form, and by bonding these particulates with the core, a shell that partially covers the core can be formed.

[0172] =Particulate polymers without a core-shell structure=

[0173] In addition to the above-mentioned particulate polymers with core-shell structures, adhesive materials may also include particulate polymers without core-shell structures.

[0174] Here, the glass transition temperature of the particulate polymer without a core-shell structure is preferably -40°C or higher, more preferably -35°C or higher, even more preferably -30°C or higher, 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 without a core-shell structure is -40°C or higher, the battery components can be more firmly bonded to each other using an adhesive material. On the other hand, if the glass transition temperature of the particulate polymer without a core-shell structure is 0°C or lower, the polymerization stability of the particulate polymer can be ensured.

[0175] As monomers for preparing particulate polymers without a core-shell structure, examples can be made of monomers that are the same monomers used as examples of monomers for preparing the core portion of the aforementioned particulate polymers with a core-shell structure. For example, (meth)acrylate monomers, aromatic vinyl monomers, acid-containing monomers, and crosslinking monomers are preferably used as monomers for preparing particulate polymers without a core-shell structure. Furthermore, such monomers can be used alone or in combination of two or more in any ratio.

[0176] From the viewpoint of further firmly bonding the battery components together via an adhesive material, the proportion of (meth)acrylate monomer units in the polymer is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less, with all repeating units (all monomer units) contained in the particulate polymer without a core-shell structure comprising 100% by mass.

[0177] From the viewpoint of further firmly bonding the battery components together via an adhesive material, the proportion of aromatic vinyl monomer units in the polymer is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, with all repeating units (all monomer units) contained in the particulate polymer without a core-shell structure being 100% by mass.

[0178] With all repeating units (all monomer units) contained in the particulate polymer without a core-shell structure as 100% by mass, the proportion of acid-containing monomer units in the polymer 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. By ensuring that the proportion of acid-containing monomer units in the particulate polymer without a core-shell structure is within the above range, the dispersibility of the particulate polymer can be improved.

[0179] From the viewpoint of further firmly bonding the battery components together via adhesive materials, the proportion of crosslinked monomer units in the polymer, which is a particulate polymer without a core-shell structure, is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less.

[0180] Furthermore, the volume average particle size of the particulate polymer without a core-shell structure is preferably 50 nm or more, more preferably 100 nm or more, and more preferably 600 nm or less. If the volume average particle size of the particulate polymer without a core-shell structure is within the above-mentioned range, the battery components can be further firmly bonded to each other by an adhesive material.

[0181] Furthermore, there are no particular limitations on the particulate polymers that do not have a core-shell structure; for example, they can be prepared by polymerizing a monomer composition containing the aforementioned monomers in an aqueous solvent such as water. Here, the proportion of each monomer in the monomer composition is generally the same as the proportion of each monomer unit in the particulate polymer that does not have a core-shell structure. Moreover, there are no particular limitations on the polymerization method and polymerization reaction; known polymerization methods and polymerization reactions can be used.

[0182] -other-

[0183] The adhesive material present in the central region P can be the same as or different from the adhesive material present in other regions Q.

[0184] Therefore, in the aforementioned "region S with densely coated adhesive material" and "region T with sparsely coated adhesive material", the same adhesive material can be applied, or different adhesive materials can be applied.

[0185] Furthermore, in the above-described "method of coating adhesive material," the adhesive material was coated in surface Z in a manner where there are "regions S in which adhesive material is densely coated" and "regions T in which adhesive material is sparsely coated." However, the laminate of the secondary battery of the present invention is not limited to this. The adhesive material can also be coated in a manner where "coating region S1" is used instead of the above-described "regions S in which adhesive material is densely coated," and "coating region S2" is used instead of the above-described "region T in which adhesive material is sparsely coated." That is, the adhesive material can also be coated in surface Z in a manner where "coating region S1" and "coating region S2" are present.

[0186] Here, the coverage rate and / or weight per unit area of ​​the adhesive material in "coating area S1" and "coating area S2" can be set within the same range as the preferred range of the coverage rate and / or weight per unit area of ​​the adhesive material in the "area S in which adhesive material is densely coated" described above. Furthermore, adhesive material can also be coated in "coating area S1" and "coating area S2" in the same manner as the coverage rate and / or weight per unit area of ​​the adhesive material.

[0187] Furthermore, the adhesive material applied in "coating area S1" is different from the adhesive material applied in "coating area S2". By appropriately selecting and using different adhesive materials as the adhesive materials applied in "coating area S1" and "coating area S2", it is possible to make the resistance A per unit area of ​​the central area P larger than the resistance B per unit area of ​​the other areas Q.

[0188] For example, granular polymers M1 and M2 with different swelling degrees can be used as adhesive materials coated in "coating area S1" and "coating area S2".

[0189] Here, the swelling degree of the particulate polymer M1 contained in the adhesive material coated in the "coating area S1" in the electrolyte (a solution of LiPF6 dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate / diethyl carbonate = 3 / 7 by volume) is preferably 800% or more, more preferably 1000% or more, and more preferably 1300% or less.

[0190] Furthermore, the swelling degree of the particulate polymer M2 contained in the adhesive material coated in the "coating area S2" in the electrolyte (a solution of LiPF6 dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate / diethyl carbonate = 3 / 7 by volume) is preferably 110% or more, preferably less than 800%, more preferably less than 500%, and even more preferably less than 300%.

[0191] By ensuring that the swelling degree of the particulate polymers M1 and M2 is within the specified range, it is possible to make the resistance A per unit area of ​​the central region P greater than the resistance B per unit area of ​​the other regions Q.

[0192] Furthermore, as particulate polymers M1 and M2, particulate polymers with a core-shell structure, such as those described in the section on "Details of Adhesive Materials," can be used. Moreover, in the aforementioned particulate polymers with a core-shell structure, as particulate polymer M1, the polymer in the core preferably comprises (meth)acrylate monomer units and (meth)acrylonitrile monomer units; and as particulate polymer M2, the polymer in the core preferably comprises (meth)acrylate monomer units and aromatic vinyl monomer units.

[0193] Furthermore, for example, the adhesive materials coated in "coating area S1" and "coating area S2" can also use granular polymers with different structures. More specifically, a granular polymer with a core-shell structure can be used as granular polymer M3 included in the adhesive material coated in "coating area S1," and a granular polymer without a core-shell structure can be used as granular polymer M4 included in the adhesive material coated in "coating area S2." Here, as granular polymer M3, for example, the granular polymer with a core-shell structure described in the "details of adhesive material" section can be used. Furthermore, as granular polymer M4, for example, a granular polymer formed solely of a polymer whose composition is the same as the polymer in the core portion of the granular polymer with a core-shell structure described in the "details of adhesive material" section can be used.

[0194] <<Methods for Manufacturing Laminated Materials>>

[0195] The manufacturing method of the laminate in the secondary battery of the present invention includes a step (A) of preparing a bonding body and a step (B) of cutting the bonding body. Optionally, if the bonding body prepared by step (A) does not have a positive electrode, the method further includes a step (C) of bonding a positive electrode to a cut body obtained by cutting the bonding body in step (B).

[0196] [Process (A)]

[0197] Here, as examples of the adhesive prepared by process (A), examples (I) and (II) can be cited below.

[0198] (I) A composite body having a strip of negative electrode raw material or negative electrode (hereinafter, sometimes referred to as "negative electrode material"), a strip of first spacer raw material attached to one surface of the negative electrode material, a strip of second spacer raw material attached to the other surface of the negative electrode material, and a positive electrode arbitrarily attached to the surface of the first spacer raw material opposite to the negative electrode material side (hereinafter, sometimes referred to as "composite body (I)").

[0199] (II) A composite body (hereinafter sometimes referred to as "composite body (II)") is formed by sequentially bonding a negative electrode material made of a strip of negative electrode raw material, a first spacer material made of a strip, a positive electrode, and a second spacer material made of a strip.

[0200] Furthermore, in the method for manufacturing the laminate in the secondary battery of the present invention, if the bonded body (I) is prepared in step (A), it is generally possible to obtain, for example... Figure 1 As shown, a laminate has a negative electrode, a first spacer attached to one surface of the negative electrode, a positive electrode attached to the surface of the first spacer opposite to the negative electrode side, and a second spacer attached to the other surface of the negative electrode.

[0201] Furthermore, in the case where the aforementioned bonding body (I) does not have a positive electrode, in the manufacturing method of the laminate in the secondary battery of the present invention, step (C) is typically performed after step (B) to manufacture the laminate.

[0202] Furthermore, in the method for manufacturing the laminate in the secondary battery of the present invention, when the bonded body (II) is prepared in step (A), it is generally possible to obtain, as follows: Figure 3 A laminate having a negative electrode, a first spacer attached to one surface of the negative electrode, a positive electrode attached to the surface of the first spacer opposite to the negative electrode side, and a second spacer attached to the surface of the positive electrode opposite to the first spacer side, as shown.

[0203] Here, the preparation of the bonding body in step (A) is generally carried out by applying an adhesive material to the bonding surfaces of the components that are bonded together, and bonding the components constituting the bonding body together via the adhesive material. That is, step (A) includes a step (a1) of applying an adhesive material to the bonding surface Y of the negative electrode material and the spacer material bonded to the negative electrode material, and may also include a step (a2) of applying an adhesive material to the bonding surface X of the spacer material and the positive electrode.

[0204] Furthermore, the "spacer raw material bonded to the negative electrode material" can be either the first spacer raw material or the second spacer raw material when the prepared bonding body is bonding body (I), and can be the first spacer raw material when the prepared bonding body is bonding body (II). Additionally, the component coated with the adhesive material can be any single component, or it can be both components bonded together.

[0205] Specifically, in process (A), for example, it is possible to... Figure 9 Prepare the adhesive (I) as shown.

[0206] Here, in Figure 9 In this process, using adhesive material supplied from coating machine 51, a strip of first spacer material 10A, rolled from first spacer material, is bonded to one surface of the negative electrode material formed from a strip of negative electrode material 20A rolled from negative electrode material. Similarly, using adhesive material supplied from coating machine 52, a strip of second spacer material 30A, rolled from second spacer material, is bonded to the other surface of the negative electrode material formed from negative electrode material 20A. Alternatively, bonding rollers 61 and 62 can be used for bonding. Then, using adhesive material supplied from coating machine 53, the positive electrode 40 is bonded at a predetermined spacing to the surface of the first spacer material 10A opposite to the negative electrode material 20A side, resulting in a bonded body (I) with a positive electrode.

[0207] In addition, Figure 9In the process, adhesive material is supplied from the coating machine 54 to the surface of the second spacer raw material 30A that is opposite to the negative electrode raw material 20A. Adhesive bodies are cut between adjacent positive electrodes 40 in the length direction, and the resulting laminates are overlapped to create an overlapping body. At this time, the laminates can be well bonded to each other.

[0208] Figure 10 To show Figure 9 An illustrative diagram of an example of a coating machine (nozzle head).

[0209] exist Figure 10 In the process, droplets 50 of adhesive material are applied to the substrate 60 via nozzles 55 of coating machines 51-54.

[0210] Furthermore, the method for preparing the bond in step (A) is not limited to the examples described above; for example, in Figure 9 Alternatively, after cutting the bonding body, the coating machine 54 can supply adhesive material to the cut body.

[0211] -Anode materials and cathode-

[0212] Here, there is no particular limitation on the electrode (negative or positive), and an electrode obtained by cutting, for example, a long strip of electrode raw material (negative or positive electrode raw material) can be used. Moreover, as the electrode raw material (negative or positive electrode raw material), an electrode substrate can be formed by forming an electrode composite material layer (negative or positive electrode composite material layer) on one or both sides of the long strip current collector, and an electrode raw material made of this electrode substrate can be used, or an electrode raw material formed by further forming a porous film layer on the electrode composite material layer of the electrode substrate can be used.

[0213] Furthermore, there are no particular limitations on the current collector, electrode composite material layer, and porous membrane layer; any current collector, electrode composite material layer, and porous membrane layer that can be used in the field of secondary batteries, such as those described in Japanese Patent Application Publication No. 2013-145763, can be used. Here, a porous membrane layer refers to a layer containing non-conductive particles, such as those described in Japanese Patent Application Publication No. 2013-145763.

[0214] -Spacer Raw Materials-

[0215] Furthermore, there are no particular limitations on the spacer material; for example, spacer materials made of a strip spacer substrate or spacer materials formed by forming a porous membrane layer on one or both sides of a strip spacer substrate can be used.

[0216] Furthermore, there are no particular limitations on the spacer substrate and porous membrane layer; any spacer substrate and porous membrane layer that can be used in the field of secondary batteries, such as those described in Japanese Patent Application Publication No. 2012-204303 and Japanese Patent Application Publication No. 2013-145763, can be used.

[0217] Furthermore, in the process of coating adhesive material onto the bonding surface Y of the spacer material that is bonded to the negative electrode material (step 1), or in the process of coating adhesive material onto the bonding surface X of the spacer material that is bonded to the positive electrode (step 2), it is preferable to coat the adhesive material in such a manner that, in at least one of the bonding surfaces X and Y, the coverage rate E of the adhesive material in the central region P, which has a center at the same position as the center R of surface Z, has a shape similar to that of surface Z, and has an area of ​​10% of the area of ​​surface Z, is greater than the coverage rate F of the adhesive material in other regions Q of surface Z excluding the central region P. This further improves the cycle characteristics of the secondary battery.

[0218] Furthermore, as a method for coating adhesive material on surface Z such that the coverage rate E of adhesive material in the central region P is greater than the coverage rate F of adhesive material in other regions Q, the adhesive material coating method described in the section on "Surface Z, Central Region P, Other Regions Q" can be used. Moreover, the coverage rate E of adhesive material in the central region P, the coverage rate F of adhesive material in other regions Q, and the range of the ratio (E / F) of coverage rate E can also be set within the preferred range described in the same section.

[0219] In addition, in process (a2), an adhesive material is applied to the bonding surface between the spacer raw material and the positive electrode.

[0220] Specifically, in the case of preparing a bonding body with a positive electrode in process (A) (e.g.) Figure 9 In the case of preparing a bonding body (a bonding body without a positive electrode) in step (A) where an adhesive material is pre-coated at the position where the positive electrode is bonded after cutting, in step (a2), an adhesive material is coated on the bonding surface between the spacer raw material and the positive electrode.

[0221] That is, for example in Figure 9 In the process, an adhesive material is applied from the coating machine 53 to the bonding surface between the first spacer raw material 10A and the positive electrode 40.

[0222] Alternatively, in process (A), it can also be done as follows: Figure 9 As shown, towards one surface of the adhesive (on Figure 9 The surface of the second spacer material 30A (which is opposite to the negative electrode material 20A) is supplied with adhesive material so that the laminates can be well bonded to each other when the laminates are made to overlap.

[0223] [Process (B)]

[0224] In step (B), the laminate is cut using a cutting machine 70. Furthermore, if the laminate with a positive electrode is cut in step (B), the resulting cut body becomes a laminate.

[0225] Here, the cutting machine 70 can be any cutting machine that can be used in the field of secondary battery manufacturing, such as a cutting machine that can clamp and cut the bonded body from both sides in the thickness direction of the bonded body using a cutting blade.

[0226] Furthermore, in process (B) performed after process (A), as described above, it is possible to suppress the spacer from curling from the negative electrode and to cut the adhesive body well.

[0227] [Process (C)]

[0228] In step (C), which can be performed arbitrarily, if the bonding body without a positive electrode is cut in step (B), the positive electrode is bonded to the cut body obtained by cutting the bonding body in step (B), and a laminate is obtained.

[0229] Electrolyte

[0230] As an electrolyte, an organic electrolyte in which the supporting electrolyte is dissolved in an organic solvent is typically used. For example, in the case of a lithium-ion secondary battery, lithium salts can be used as the supporting electrolyte. Examples of lithium salts include: LiPF6, LiAsF6, LiBF4, LiSbF6, LiAlCl4, LiClO4, CF3SO3Li, C4F9SO3Li, CF3COOLi, (CF3CO)2NLi, (CF3SO2)2NLi, (C2F5SO2)NLi, etc.

[0231] Among these, LiPF6, LiClO4, and CF3SO3Li are preferred due to their easy solubility in solvents and high degree of dissociation, with LiPF6 being particularly preferred. Furthermore, the electrolyte can be used alone or in combination of two or more in any ratio. Since there is a general tendency that using a supporting electrolyte with a higher degree of dissociation results in higher lithium-ion conductivity, the lithium-ion conductivity can be adjusted by the type of supporting electrolyte.

[0232] As for organic solvents used in electrolytes, there are no particular limitations as long as they can dissolve the supporting electrolyte. Preferred solvents include: carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butyl carbonate (BC), methyl ethyl 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. Mixtures of these solvents can also be used. Among these, carbonates are preferred because of their high dielectric constant and wide stable potential range.

[0233] Since there is a general tendency that the lower the viscosity of the solvent used, the higher the lithium-ion conductivity, the lithium-ion conductivity can be adjusted by the type of solvent.

[0234] Furthermore, the concentration of the electrolyte in the electrolyte solution can be appropriately adjusted. In addition, known additives can be added to the electrolyte solution.

[0235] The secondary battery of the present invention can be manufactured, for example, as follows: according to the battery shape, an overlapping body obtained by overlapping and stacking is wound, folded, etc., placed in a device container (battery container), electrolyte is injected into the device container, and the container is sealed. Alternatively, the overlapping body can be the stacked body itself, or multiple stacked bodies can be used. Furthermore, the overlapping body can also be manufactured by overlapping the stacked body with additional battery components (electrodes and / or spacers, etc.). In addition, in the secondary battery of the present invention, to prevent internal pressure rise, overcharge and discharge, etc., overcurrent protection components such as fuses and PTC elements, porous metal mesh, and conductive plates can be provided as needed. The shape of the secondary battery can be, for example, coin-shaped, button-shaped, sheet-shaped, cylindrical, square, flat, etc.

[0236] (Manufacturing method of secondary batteries)

[0237] The manufacturing method of the secondary battery of the present invention is a method for manufacturing a secondary battery having a positive electrode, a spacer, and a negative electrode stacked in sequence. Furthermore, the manufacturing method of the secondary battery of the present invention is characterized by a step (coating step) of coating an adhesive material onto at least one of the surfaces X (the bonding surface between the positive electrode and the spacer) and Y (the bonding surface between the negative electrode and the spacer) under predetermined conditions on a surface Z.

[0238] Furthermore, the secondary battery manufacturing method according to the present invention can produce a secondary battery with excellent cycle characteristics.

[0239] Furthermore, the manufacturing method according to the present invention enables the efficient manufacture of the secondary battery of the present invention described above.

[0240] In addition, the manufacturing method of the secondary battery of the present invention may also include other steps besides the coating step described above.

[0241] <Coating Process>

[0242] In the coating process, adhesive material is coated on surface Z in the following manner: surface Z is defined as at least one of the bonding surface X of the positive electrode and the spacer and the bonding surface Y of the negative electrode and the spacer. The coverage rate E of adhesive material in the central region P is greater than the coverage rate F of adhesive material in other regions Q of surface Z except for the central region P. The central region P has a shape similar to that of surface Z, has a center at the same position as the center of surface Z, and has an area of ​​10% of the area of ​​surface Z.

[0243] Furthermore, as a method for coating adhesive material on surface Z such that the coverage rate E of adhesive material in the central region P is greater than the coverage rate F of adhesive material in other regions Q, the adhesive material coating method described in the section on "secondary battery" can be used.

[0244] Furthermore, the coverage rate E of the adhesive material in the central region P, the coverage rate F of the adhesive material in other regions Q, and the range of the ratio (E / F) of coverage rate E can also be set within the preferred range described in the "secondary battery" section.

[0245] Furthermore, the positive electrode, spacer, negative electrode, and adhesive material described in the "secondary battery" section can be used as the positive electrode, spacer, negative electrode, and adhesive material for the coating process.

[0246] <Other processes>

[0247] Other examples of processes include lamination and assembly processes.

[0248] <<Layering Process>>

[0249] In the lamination process, after coating the Z-side with adhesive material under the conditions specified above, the positive electrode, spacer, and negative electrode are sequentially laminated to obtain a laminate.

[0250] Alternatively, the manufacturing method of the laminate described in the "secondary battery" section can be used to obtain the laminate by performing the above-mentioned coating process and lamination process as part of the manufacturing method of the laminate.

[0251] Assembly Process

[0252] The assembly process is the process of assembling a secondary battery using a laminate and an electrolyte. For example, the process is as follows: the laminate obtained by overlapping the laminate is further laminated with additional battery components (electrodes and / or spacers, etc.) as needed, and then the resulting laminate is placed into a battery container, electrolyte is injected into the battery container and it is sealed, thereby assembling the battery.

[0253] Example

[0254] The present invention will now be described in detail based on embodiments, but the present invention is not limited to these embodiments. Furthermore, in the following description, unless otherwise specified, "%" and "parts" refer to quantities based on mass.

[0255] Furthermore, in polymers manufactured by copolymerizing multiple monomers, unless otherwise specified, the proportion of monomer units formed by polymerizing a particular monomer in the polymer is usually consistent with the proportion (feed ratio) of that particular monomer in all monomers used in the polymerization of the polymer.

[0256] Furthermore, in the manufacturing examples, embodiments, and comparative examples, the glass transition temperature, volume average particle size, degree of swelling, shape of the adhesive material, unit area weight of the coated area, dry adhesion between the electrode and the spacer, cycle characteristics of the secondary battery, output characteristics, and temperature difference during discharge were measured and evaluated by the following methods.

[0257] Glass transition temperature

[0258] Aqueous dispersions of the particulate polymers prepared in Examples 1-6 were dried at 130°C for 1 hour to prepare samples. 10 mg of the sample was weighed into an aluminum pan, and a differential scanning calorimetry (DSC) measurement was performed using a Seiko Nanotechnology Corporation EXSTAR DSC6220 device within the measurement temperature range of -100°C to 200°C, at a heating rate of 10°C / min, under the conditions specified in JIS Z8703, to obtain a DSC curve. An empty aluminum pan was used as a reference. During the heating process, the glass transition temperature (°C) was determined by intersecting the baseline of the DSC curve before the endothermic peak appears (when the differential signal (DDSC) is 0.05 mW / min / mg or higher) with the tangent line of the DSC curve at the first inflection point after the endothermic peak.

[0259] <Volume average particle size>

[0260] The volume average particle size of the particulate polymers prepared in each manufacturing example was determined using laser diffraction. Specifically, an aqueous dispersion solution (solid component concentration 0.1% by mass) containing the prepared particles was used as a sample. The particle size distribution (volume basis) obtained using a laser diffraction particle size distribution measuring device (Beckman Coulter, product name "LS-13 320") was used to determine the particle size at which the cumulative volume from the smallest particle size side reached 50%, which was taken as the volume average particle size D50 (nm).

[0261] <Swelling Degree>

[0262] The aqueous dispersions of the particulate polymers prepared in each manufacturing example were dried. Approximately 0.2 g of the dried product was pressed at 200°C and 5 MPa for 2 minutes to obtain a membrane. The obtained membrane was cut into 1 cm square pieces as test pieces, and the mass W2 (g) of the test pieces was measured. Next, the test pieces were immersed in an electrolyte (a solution of LiPF6 dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate / diethyl carbonate = 3 / 7 by volume) at 60°C for 72 hours. Afterward, the test pieces were removed from the mixed solvent, the mixed solvent on the surface was wiped off, and the mass W3 (g) of the test pieces was measured. Then, the swelling degree (%) was calculated according to the following formula.

[0263]

[0264] <Shape of adhesive material>

[0265] The shape of the adhesive material coated on the bonding surface was observed using a laser microscope (Keyence, VR-3100).

[0266] <Weight per unit area of ​​adhesive material>

[0267] For each region, the weight per unit area of ​​the adhesive material is calculated based on the mass difference per unit area before and after the adhesive composition is supplied and dried.

[0268] <Adhesion force between electrode and spacer>

[0269] Under the same conditions as in the embodiments and comparative examples, a negative electrode and a spacer coated with adhesive material on one side were pressed for 10 seconds at a temperature of 70°C and a pressure of 1 MPa, and the laminated body (i.e., a laminate formed by bonding a negative electrode and a spacer with adhesive material) was collected as a test piece.

[0270] With the current collector side of the negative electrode facing down, apply transparent tape to the surface of the current collector side of the negative electrode. Use the transparent tape specified in JIS Z1522. The transparent tape is fixed to a horizontal test bench. Then, stretch one end of the spacer vertically upwards at a tensile speed of 50 mm / min and measure the stress upon peeling.

[0271] A total of six measurements were performed, and the average stress was used as the peel strength. The adhesion between the negative electrode and the spacer was evaluated using the following criteria. A higher peel strength indicates a stronger adhesion between the electrode (negative electrode) and the spacer.

[0272] A: Peel strength is above 1.5 N / m

[0273] B: Peel strength is above 1.0 N / m and less than 1.5 N / m

[0274] C: Peel strength is ≥0.5 N / m and <1.0 N / m

[0275] D: Peel strength is less than 0.5 N / m.

[0276] <Cycle Characteristics of Secondary Batteries>

[0277] After electrolyte filling, the lithium-ion secondary batteries prepared in the examples and comparative examples were left to stand at 25°C for 5 hours. Next, they were charged at 25°C using a constant current method at 0.2C to a cell voltage of 3.65V, followed by an aging treatment at 60°C for 12 hours. Then, they were discharged at 25°C using a constant current method at 0.2C to a cell voltage of 3.00V. Afterward, they were subjected to CC-CV charging at a constant current of 0.2C (upper limit cell voltage 4.30V) and CC discharging at a constant current of 0.2C to 3.00V.

[0278] Subsequently, 100 charge-discharge cycles were performed at a temperature of 45°C, with a battery voltage of 4.30-3.00V and a charge-discharge rate of 1.0C. The capacity of the first cycle (initial discharge capacity X1) and the discharge capacity of the 100th cycle (X2) were then measured. The capacity retention rate (%) was calculated as (X2 / X1) × 100, and evaluated according to the following criteria. A higher capacity retention rate indicates better cycle characteristics of the secondary battery.

[0279] A: Capacity retention rate is above 90%.

[0280] B: Capacity retention rate is above 85% and below 90%.

[0281] C: Capacity retention rate is above 80% and below 85%.

[0282] D: Capacity retention rate less than 80%

[0283] <Output Characteristics>

[0284] The prepared lithium-ion secondary battery was charged to 4.3V using a constant current constant voltage (CCCV) method at 25°C to prepare battery cells. The prepared battery cells were then discharged to 3.0V using constant current methods at 0.2C and 1C at -10°C, and the capacity was calculated. The discharge capacity retention rate, expressed as the ratio of capacitance (1C capacity / 0.2C capacity) × 100 (%), was then calculated. These measurements were performed on five lithium-ion secondary battery cells, and the average of the calculated discharge capacity retention rates was used as the output characteristic, evaluated using the following benchmark. A higher value indicates better output characteristics.

[0285] A: The average discharge capacity retention rate is over 80%.

[0286] B: The average discharge capacity retention rate is above 70% and below 80%.

[0287] C: The average discharge capacity retention rate is above 60% and below 70%.

[0288] D: The average discharge capacity retention rate is less than 60%.

[0289] (Manufacturing Example 1)

[0290] <Manufacturing of Particulate Polymer 1>

[0291] In a reactor equipped with a stirrer, 100 parts of ion-exchanged water and 0.3 parts of ammonium persulfate were supplied, the gas phase was purged with nitrogen, and the temperature was raised to 80°C. Meanwhile, in another container, 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)acrylate monomer, 2.1 parts of methacrylic acid as an acidic monomer, and 0.3 parts of ethylene glycol dimethacrylate as a crosslinking monomer were mixed to obtain a core-forming monomer composition. This core-forming monomer composition was continuously added to the reactor for 3 hours, and polymerization was carried out at 80°C. By continuing polymerization until the polymerization conversion reached 95%, an aqueous dispersion containing particulate polymer constituting the core was obtained. Next, a shell-forming monomer composition comprising 29.7 parts of styrene as an aromatic monovinyl monomer and 0.3 parts of methacrylic acid as an acidic monomer was continuously fed into the aqueous dispersion for 60 minutes, and polymerization continued. When the polymerization conversion reached 98%, the reaction was terminated by cooling, thereby preparing an aqueous dispersion containing particulate polymer 1.

[0292] The volume-average particle size, swelling degree, and glass transition temperature of the obtained particulate polymer 1 were determined. The results are shown in Table 1.

[0293] Furthermore, by observing the cross-sectional structure of the particulate polymer using transmission electron microscopy (TEM), it was confirmed that the particulate polymer has a core-shell structure in which the shell partially covers the outer surface of the core.

[0294] (Manufacturing Example 2)

[0295] <Manufacturing of Particulate Polymer 2>

[0296] In the manufacture of the particulate polymer of Manufacturing Example 1, instead of the core-forming monomer composition comprising 40.3 parts of styrene as an aromatic monovinyl monomer, 27.3 parts of 2-ethylhexyl acrylate as a monofunctional (meth)acrylate monomer, 2.1 parts of methacrylic acid as an acidic monomer, and 0.3 parts of ethylene glycol dimethacrylate as a crosslinking monomer, the core-forming monomer composition comprising 17.0 parts of methyl methacrylate as a monofunctional (meth)acrylate monomer, 36.1 parts of butyl acrylate as a monofunctional (meth)acrylate monomer, 14.0 parts of acrylonitrile as a (meth)acrylonitrile monomer, 2.8 parts of methacrylic acid as an acidic monomer, and 0.1 parts of ethylene glycol dimethacrylate as a crosslinking monomer was used. Otherwise, the process was the same as in Manufacturing Example 1, and an aqueous dispersion of particulate polymer 2 with a core-shell structure was prepared. Then, various measurements were performed as in Manufacturing Example 1. The results are shown in Table 1.

[0297] <Manufacturing of Particulate Polymer 3>

[0298] In the manufacture of the particulate polymer of Manufacturing Example 1, instead of a core-forming monomer composition comprising 40.3 parts of styrene as an aromatic monovinyl monomer, 27.3 parts of 2-ethylhexyl acrylate as a monofunctional (meth)acrylate monomer, 2.1 parts of methacrylic acid as an acid-containing monomer, and 0.3 parts of ethylene glycol dimethacrylate as a crosslinking monomer, a monomer composition comprising 57.6 parts of styrene as an aromatic monovinyl monomer, 39.0 parts of 2-ethylhexyl acrylate as a monofunctional (meth)acrylate monomer, 3.0 parts of methacrylic acid as an acid-containing monomer, and 0.4 parts of ethylene glycol dimethacrylate as a crosslinking monomer was used, and the shell-forming monomer composition was not supplied. Otherwise, the process was the same as in Manufacturing Example 1, and an aqueous dispersion of particulate polymer 3 without a core-shell structure was prepared. Then, various measurements were performed in the same manner as in Manufacturing Example 1. The results are shown in Table 1.

[0299] (Manufacturing Example 4)

[0300] <Manufacturing of Particulate Polymer 4>

[0301] In a reactor equipped with a stirrer, 90 parts of ion-exchanged water and 0.5 parts of ammonium persulfate were supplied, the gas phase was replaced with nitrogen, and the temperature was raised to 80°C. Meanwhile, in another container, 15 parts of ion-exchanged water, 1.0 part of Neo Pelex G15 (manufactured by Kao Chemical Co., Ltd.) as an emulsifier, 70.0 parts of 2-ethylhexyl acrylate as a monofunctional (meth)acrylate monomer, 25.0 parts of styrene as an aromatic monovinyl monomer, 1.7 parts of allyl glycidyl ether as a crosslinking monomer, 0.3 parts of allyl methacrylate as a crosslinking monomer, and 3.0 parts of acrylic acid as an acid-containing monomer were mixed to obtain a monomer composition.

[0302] The monomer composition was continuously added to the reactor over a period of 4 hours to carry out polymerization. During the continuous addition, the reaction was conducted at 80°C. After the continuous addition was completed, the mixture was stirred at 80°C for an additional 3 hours to terminate the reaction.

[0303] After cooling the obtained aqueous dispersion to 25°C, an aqueous sodium hydroxide solution was added to adjust the pH to 8.0. Then, steam was introduced to remove unreacted monomers, resulting in an aqueous dispersion of particulate polymer 4 without a core-shell structure. Various measurements were then performed in the same manner as in Manufacturing Example 1. The results are shown in Table 1.

[0304] (Manufacturing Example 5)

[0305] In the manufacture of the particulate polymer of Manufacturing Example 1, instead of a core-forming monomer composition comprising 40.3 parts of styrene as an aromatic monovinyl monomer, 27.3 parts of 2-ethylhexyl acrylate as a monofunctional (meth)acrylate monomer, 2.1 parts of methacrylic acid as an acid-containing monomer, and 0.3 parts of ethylene glycol dimethacrylate as a crosslinking monomer, a core-forming monomer composition comprising 20.2 parts of styrene as an aromatic monovinyl monomer, 47.6 parts of 2-ethylhexyl acrylate as a monofunctional (meth)acrylate monomer, 2.1 parts of methacrylic acid as an acid-containing monomer, and 0.1 parts of ethylene glycol dimethacrylate as a crosslinking monomer was used. Otherwise, the process was the same as in Manufacturing Example 1, and an aqueous dispersion of particulate polymer 5 with a core-shell structure was prepared. Then, various measurements were performed as in Manufacturing Example 1. The results are shown in Table 1.

[0306] (Manufacturing Example 6)

[0307] In the manufacture of the particulate polymer in Manufacturing Example 5, in addition to supplying 100 parts of deionized water and 0.3 parts of ammonium persulfate, 0.03 parts of sodium dodecylbenzenesulfonate as an emulsifier were also supplied to a reactor equipped with a stirrer. Otherwise, the process was carried out in the same manner as in Manufacturing Example 5 to prepare an aqueous dispersion of particulate polymer 6 with a core-shell structure. Then, various measurements were performed in the same manner as in Manufacturing Example 1. The results are shown in Table 1.

[0308] (Example 1)

[0309] <Preparation of Adhesive Compositions>

[0310] The aqueous dispersion of particulate polymer 1 obtained in Manufacturing Example 1 and the aqueous dispersion of particulate polymer 4 obtained in Manufacturing Example 4 were mixed at a solid content mass ratio of 100:10. Then, deionized water was added to dilute the mixture to a solid content concentration of 10.5%. Propylene glycol was further added to the resulting mixture to adjust the solid content concentration to 10%, thereby obtaining adhesive composition 1.

[0311] <Production of Anode Raw Materials>

[0312] In a 5 MPa pressure vessel equipped with a stirrer, 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 deionized water, and 0.5 parts of potassium persulfate as a polymerization initiator were added. After thorough stirring, the mixture was heated to 50°C to initiate polymerization. The reaction was terminated by cooling when the polymerization conversion reached 96%, yielding a mixture containing a binder material for the negative electrode composite layer (SBR). A 5% sodium hydroxide aqueous solution was added to the mixture to adjust the pH to 8, and unreacted monomers were removed by heated vacuum distillation. The mixture was then cooled to below 30°C to obtain an aqueous dispersion containing the desired binder material for the negative electrode composite layer.

[0313] Next, 100 parts of a 2% aqueous solution of artificial graphite (volume average particle size: 15.6 μm) as the negative electrode active material, 1 part of a 2% aqueous solution of sodium carboxymethyl cellulose (manufactured by Nippon Paper Corporation, product name "MAC350HC") as a viscosity modifier (based on the solids content), and deionized water were mixed to adjust the solids content concentration to 68%, and then mixed for 60 minutes at 25°C. The solids content concentration was then adjusted to 62% using deionized water, and the mixture was further mixed for 15 minutes at 25°C. To the resulting mixture, 1.5 parts of the above-mentioned aqueous dispersion containing the binder material for the negative electrode composite layer (based on the solids content), and deionized water were added to adjust the final solids content concentration to 52%, and the mixture was further mixed for 10 minutes. The mixture was then degassed under reduced pressure to obtain a slurry composition for a secondary battery negative electrode with good flowability.

[0314] Using a corner-cutting roller coating machine, the obtained secondary battery negative electrode slurry composition was coated onto both sides of a 20 μm thick copper foil serving as the current collector, with a dried film thickness of approximately 150 μm, and then dried. This drying was performed by conveying the copper foil at a speed of 0.5 m / min in an oven at 60°C for 2 minutes. Afterward, it was heat-treated at 120°C for 2 minutes to obtain the negative electrode raw material before pressing. This unpressed negative electrode raw material was then calendered using a roller press to obtain a pressed negative electrode raw material with a negative electrode composite layer thickness of 80 μm.

[0315] <Production of Positive Electrode Raw Materials>

[0316] 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 Denki Kagaku Kogyo Co., Ltd., product name "HS-100") as the conductive material, 2 parts of polyvinylidene fluoride (manufactured by Kureha Co., Ltd., product name "#7208") as the binder, and N-methylpyrrolidone as the solvent were mixed to achieve a total solids concentration of 70%. These were then mixed using a planetary mixer to obtain a slurry composition for the positive electrode of a secondary battery.

[0317] Using a corner-shaped coating machine, the obtained secondary battery positive electrode slurry composition was coated onto both sides of a 20 μm thick aluminum foil serving as a current collector, with a dried film thickness of 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 60°C for 2 minutes. Afterwards, a heat treatment was performed at 120°C for 2 minutes to obtain the positive electrode raw material.

[0318] Then, the obtained cathode raw material is calendered using a roller press to obtain a pressed cathode raw material with a cathode composite material layer.

[0319] <Preparation of spacer raw materials>

[0320] Prepare the raw materials for the spacer made of polypropylene (PP) (product name "Celgard2500").

[0321] <Fabrication of Layered Structures>

[0322] Using the prepared adhesive composition, negative electrode raw material, positive electrode raw material, and spacer raw material, such as Figure 11 The layered structure is fabricated as shown. Additionally, in... Figure 11 In the attached drawing, reference numeral 91 indicates the conveying roller, and reference numeral 92 indicates the heating roller.

[0323] Specifically, while conveying negative electrode material 20A from a negative electrode material roll at a speed of 10 m / min, an adhesive composition is supplied to one surface of the negative electrode material 20A from the inkjet head of an inkjet coating machine 52 (manufactured by Konica Minolta, KM1024 (shear mode type)). Second spacer material 30A, from a spacer material roll, is bonded to the negative electrode material 20A using pressing rollers 61 and 62. Furthermore, an adhesive composition is supplied to the other surface of the negative electrode material 20A from the inkjet coating machine 51 (manufactured by Konica Minolta, KM1024 (shear mode type)). First spacer material 10A, from a spacer material roll, is bonded to the laminate of the negative electrode material 20A and the second spacer material 30A using pressing rollers 61 and 62. Next, an adhesive composition is supplied from the inkjet head of an inkjet coating machine 53 (Konica Corporation, KM1024 (shear mode type)) to the surface of the first spacer material 10A opposite to the negative electrode material 20A. After the pre-cut positive electrode 40 is placed on it, the laminate of the first spacer material 10A, the negative electrode material 20A, and the second spacer material 30A is bonded to the positive electrode 40 using pressing rollers 61 and 62. Then, after the adhesive composition is supplied from the inkjet head of an inkjet coating machine 54 (Konica Corporation, KM1024 (shear mode type)) to the positive electrode 40, it is cut by a cutting machine 70 to obtain a laminate formed by sequentially stacking the second spacer, the negative electrode, the first spacer, and the positive electrode.

[0324] In addition, the bonding is performed using pressing rollers 61 and 62 at a temperature of 70°C and a pressure of 1 MPa.

[0325] Furthermore, the supplied adhesive composition is dried by using a heated roller 92 on a portion of the conveying roller 91 (drying temperature: 70°C, drying time: 1 second).

[0326] Here, the adhesive composition is supplied from coating machines 51 to 54 as shown in Table 2. Specifically, the area with a center at the same position as the center of the bonding surfaces X and Y of the electrode and the spacer, having a shape similar to the shape of the bonding surfaces X and Y, and having an area of ​​10% of the area of ​​the bonding surfaces X and Y, is designated as "area S with densely coated adhesive material" in Table 2. The area of ​​the bonding surfaces X and Y other than "area S with densely coated adhesive material" is designated as "area T with sparsely coated adhesive material". The adhesive composition is applied (supplied) such that the "coverage rate of adhesive material" in "area S with densely coated adhesive material" is 3.0% and the "weight per unit area of ​​adhesive material" is 0.180 g / m². 2 The "adhesive material coverage rate" in the "area T with sparsely coated adhesive material" is 0.79%, and the "weight per unit area of ​​adhesive material" is 0.044 g / m². 2 Furthermore, the "adhesive material" in both "coverage rate of adhesive material" and "weight per unit area of ​​adhesive material" refers to the adhesive composition after drying to remove the solvent. Here, as the coated adhesive composition, the aforementioned adhesive composition 1 is used in either the "region S where adhesive material is densely coated" or the "region T where adhesive material is sparsely coated". Moreover, in either the "region S where adhesive material is densely coated" or the "region T where adhesive material is sparsely coated", the adhesive composition is applied in a dotted pattern. Furthermore, observation of the dried adhesive composition (as the dried adhesive material) using a laser microscope revealed multiple adhesive materials arranged in a tiny dotted pattern on the bonding surface. In either the "region S where adhesive material is densely coated" or the "region T where adhesive material is sparsely coated", the dot size of the adhesive material arranged in a dotted pattern is 40 μm in diameter.

[0327] By coating as described above, the coverage rate E of the adhesive material in the central region P, which has a center at the same position as the center of the mating surfaces X and Y of the electrode and the spacer, a shape similar to that of the mating surfaces X and Y, and an area accounting for 10% of the area of ​​the mating surfaces X and Y, is 3.0%, and the unit area weight of the adhesive material is 0.180 g / m². 2 The coverage rate F of the adhesive material in areas Q of the bonding surfaces X and Y, excluding the central area P, is 0.79%, and the unit area weight of the adhesive material is 0.044 g / m². 2 .

[0328] Then, the adhesive strength of the laminate was evaluated. The results are shown in Table 2.

[0329] <Manufacturing of Secondary Batteries and Measurement of Resistance per Unit Area>

[0330] The laminated battery was packaged using aluminum packaging material as the outer packaging. Electrolyte (solvent: ethylene carbonate / diethyl carbonate / ethylene carbonate = 68.5 / 30 / 1.5 (volume ratio), electrolyte: 1M LiPF6) was injected. The opening of the aluminum packaging material was then sealed by heat sealing at 150°C, thus manufacturing the lithium-ion secondary battery. After electrolyte injection, the battery was allowed to stand at 25°C for 5 hours. Next, it was charged at 25°C using a constant current method at 0.2C to a cell voltage of 3.65V, followed by an aging treatment at 60°C for 12 hours. Then, it was discharged at 25°C using a constant current method at 0.2C to a cell voltage of 3.00V. Finally, it was charged using a constant current method at 0.2C (upper limit cell voltage 4.30V) and discharged using a constant current method at 0.2C to 3.00V.

[0331] Afterwards, the charge was increased to 50% SOC (State of Charge), and the assembly was disassembled in an inert gas environment. Five 1cm² effective area sections were randomly punched out from the central region P of the disassembled laminate. 2 The electrode assembly was connected to the tab wires and packaged in aluminum packaging material. The electrolyte was then injected to create five secondary batteries, each consisting only of a central region P. The average DC resistance of each battery during discharge at a discharge rate of 3C and a discharge time of 10 seconds was taken as the resistance A per unit area of ​​the central region P. The "DC resistance" referred to here is the resistance value calculated using the following formula, with the voltage before discharge (0 seconds) set as V0 and the voltage after 10 seconds set as V1.

[0332] DC resistance = 1cm 2 The current value of ×(V1-V0) / 3C

[0333] Furthermore, similarly to the above, 10 electrode sets with an effective area of ​​1cm × 1cm were randomly punched out from regions Q other than the central region P of the disassembled laminate, and secondary batteries consisting only of the other regions Q were fabricated using the same method. The average DC resistance value of the fabricated batteries when discharged under the same conditions as described above was taken as the resistance B per unit area of ​​the other regions Q, and the resistance ratio (A / B) is shown in Table 2.

[0334] Furthermore, five laminates prepared as described above were stacked and pressed at 70°C and 1 MPa for 10 seconds to obtain an overlap. This overlap was then packaged in an aluminum outer packaging material, and the electrolyte (solvent: ethylene carbonate / diethyl carbonate / ethylene carbonate = 68.5 / 30 / 1.5 (volume ratio), electrolyte: 1M LiPF6) was injected. The opening of the aluminum outer packaging was then sealed by heat sealing at 150°C, producing a laminated lithium-ion secondary battery with a capacity of 800 mAh. The cycle characteristics and output characteristics of the obtained secondary battery were evaluated. The results are shown in Table 2.

[0335] (Example 2)

[0336] In the manufacture of the laminate in Example 1, the area of ​​the "region S in which the adhesive material is densely coated" was changed from 10% to 20% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "region T in which the adhesive material is sparsely coated" was changed from 90% to 80% of the area of ​​the bonding surfaces X and Y. Otherwise, the same procedure as in Example 1 was followed to manufacture and prepare the adhesive composition, the negative electrode raw material, the positive electrode raw material, the spacer raw material, the laminate, and the secondary battery.

[0337] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0338] Furthermore, by changing the areas of the "densely coated adhesive region S" and the "sparsely coated adhesive region T," since the central region P consists only of the "densely coated adhesive region S," the adhesive coverage E in the central region P remains 3.0%, and the unit area weight of the adhesive remains 0.180 g / m². 2 However, in other regions Q, due to the presence of portions equivalent to "densely coated adhesive material region S" and portions equivalent to "sparsely coated adhesive material region T", the adhesive material coverage F in other regions Q becomes 1.04%, and the adhesive material weight per unit area becomes 0.059 g / m². 2 Furthermore, in other regions Q, where there is a mixture of regions S (corresponding to "densely coated adhesive material") and regions T (corresponding to "sparsely coated adhesive material"), the coverage rate F and weight per unit area of ​​the adhesive material in other regions Q can be calculated using the following formula.

[0339] (Coverage rate F) = (Coverage rate of adhesive material in densely coated region S) × (Ratio of densely coated region S to other regions Q) + (Coverage rate of adhesive material in sparsely coated region T) × (Ratio of sparsely coated region T to other regions Q)

[0340] (Weight per unit area) = (Weight per unit area of ​​adhesive material in densely coated region S) × (Ratio of densely coated region S to other regions Q) + (Weight per unit area of ​​adhesive material in sparsely coated region T) × (Ratio of sparsely coated region T to other regions Q)

[0341] (Example 3)

[0342] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (spacing) of the adhesive composition supplied as dots in the "region S with densely coated adhesive material" and the "region T with sparsely coated adhesive material," without changing the coverage ratio of the adhesive material in each of the two regions, the dot size of the adhesive composition supplied as dots was changed from a diameter of 40 μm to a diameter of 80 μm. As a result, the unit area weight of the adhesive material in the "region S with densely coated adhesive material" became 0.124 g / m². 2 The weight per unit area of ​​the adhesive material in the "sparsely coated area T" becomes 0.031 g / m². 2 Then, in the same manner as in Example 1, the bonding composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery were prepared.

[0343] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0344] (Example 4)

[0345] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (spacing) of the adhesive composition supplied as dots in the "region S with densely coated adhesive material" and the "region T with sparsely coated adhesive material", without changing the coverage ratio of the adhesive material in each of the "region S with densely coated adhesive material" and the "region T with sparsely coated adhesive material", the dot size of the adhesive composition supplied as dots was changed from a diameter of 40 μm to a diameter of 20 μm. As a result, the unit area weight of the adhesive material in the "region S with densely coated adhesive material" became 0.158 g / m². 2 The unit area weight of the adhesive material in the "sparsely coated area T" becomes 0.040 g / m². 2 Then, in the same manner as in Example 1, the bonding composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery were prepared.

[0346] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0347] (Example 5)

[0348] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (spacing) of the adhesive composition supplied as dots in the "sparsely coated adhesive material region T", the coverage rate of the adhesive material in the "sparsely coated adhesive material region T" was changed from 0.79% to 0.35%, and the unit area weight of the adhesive material was changed from 0.044 g / m². 2 Change to 0.022g / m 2 In addition, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode material, positive electrode material, spacer material, laminate, and secondary battery.

[0349] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0350] (Example 6)

[0351] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (spacing) of the adhesive composition supplied as dots in the "sparsely coated adhesive material region T", the coverage rate of the adhesive material in the "sparsely coated adhesive material region T" was changed from 0.79% to 0.20%, and the unit area weight of the adhesive material was changed from 0.044 g / m². 2 Change to 0.011g / m 2 In addition, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode material, positive electrode material, spacer material, laminate, and secondary battery.

[0352] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0353] (Example 7)

[0354] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (spacing) of the adhesive composition supplied as dots in the "sparsely coated adhesive material region T", the coverage of the adhesive material in the "sparsely coated adhesive material region T" was changed from 0.79% to 1.40%, and the unit area weight of the adhesive material was changed from 0.044 g / m². 2 Change to 0.079g / m 2 In addition, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode material, positive electrode material, spacer material, laminate, and secondary battery.

[0355] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0356] (Example 8)

[0357] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (spacing) of the adhesive composition supplied as dots in the "region S where adhesive material is densely coated", the coverage rate of the adhesive material in the "region S where adhesive material is densely coated" was changed from 3.00% to 5.60%, and the unit area weight of the adhesive material was changed from 0.180 g / m². 2 Change to 0.316g / m 2 In addition, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode material, positive electrode material, spacer material, laminate, and secondary battery.

[0358] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0359] (Example 9)

[0360] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (spacing) of the adhesive composition supplied as dots in the "region S where adhesive material is densely coated", the coverage rate of the adhesive material in the "region S where adhesive material is densely coated" was changed from 3.00% to 12.57%, and the unit area weight of the adhesive material was changed from 0.180 g / m². 2 Change to 0.712g / m 2 In addition, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode material, positive electrode material, spacer material, laminate, and secondary battery.

[0361] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0362] (Example 10)

[0363] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (spacing) of the adhesive composition supplied as dots in the "region S where adhesive material is densely coated", the coverage rate of the adhesive material in the "region S where adhesive material is densely coated" was changed from 3.00% to 1.40%, and the unit area weight of the adhesive material was changed from 0.180 g / m². 2 Change to 0.079g / m 2 In addition, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode material, positive electrode material, spacer material, laminate, and secondary battery.

[0364] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0365] (Example 11)

[0366] In the manufacture of the laminate in Example 1, the supply shape of the adhesive composition in the "region S in which the adhesive material is densely coated" and the "region T in which the adhesive material is sparsely coated" was changed from a dotted pattern to a striped pattern; the coverage rate of the adhesive material in the "region S in which the adhesive material is densely coated" was changed from 3.00% to 9.09%; and the unit area weight of the adhesive material was changed from 0.180 g / m². 2 Change to 0.400g / m 2 The coverage rate of the adhesive material in the "sparsely coated area T" was changed from 0.79% to 3.61%, and the unit area weight of the adhesive material was changed from 0.044 g / m². 2 Change to 0.100g / m 2 In addition, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode material, positive electrode material, spacer material, laminate, and secondary battery.

[0367] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0368] (Example 12)

[0369] In the manufacture of the laminate in Example 1, the adhesive composition coated on the "region S in which adhesive material is densely coated" and the "region T in which adhesive material is sparsely coated" was changed from the adhesive composition 1 prepared in Manufacturing Example 1 to the adhesive composition 4 prepared as described below. Otherwise, the same procedure as in Example 1 was followed to manufacture and prepare the adhesive composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0370] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0371] <Preparation of Adhesive Composition 4>

[0372] Add 5 parts of sodium dodecylbenzenesulfonate to 100 parts of ion-exchanged water, stir with a disperser, and slowly add 10 parts of vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP; Arkema "LBG") powder. Stir for 2 hours to obtain an aqueous dispersion of PVdF-HFP with a solids concentration of 10.5%. Further add propylene glycol to the obtained aqueous dispersion to adjust the solids concentration to 10%, obtaining adhesive composition 4.

[0373] (Example 13)

[0374] In the manufacture of the laminate in Example 1, the area of ​​the "region S in which the adhesive material is densely coated" was changed from 10% to 50% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "region T in which the adhesive material is sparsely coated" was changed from 90% to 50% of the area of ​​the bonding surfaces X and Y. Otherwise, the same procedure as in Example 1 was followed to manufacture and prepare the adhesive composition, the negative electrode raw material, the positive electrode raw material, the spacer raw material, the laminate, and the secondary battery.

[0375] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0376] Furthermore, by changing the areas of the "densely coated adhesive region S" and the "sparsely coated adhesive region T," since the central region P consists only of the "densely coated adhesive region S," the adhesive coverage E in the central region P remains 3.0%, and the unit area weight of the adhesive remains 0.180 g / m². 2 However, in other regions Q, due to the presence of portions equivalent to "densely coated adhesive material region S" and portions equivalent to "sparsely coated adhesive material region T", the adhesive material coverage F in other regions Q becomes 1.77%, and the adhesive material weight per unit area becomes 0.104 g / m². 2 .

[0377] (Example 14)

[0378] In the fabrication of the laminate in Example 1, "coating region S1" is used instead of "region S where adhesive material is densely coated". In this "coating region S1", the coverage rate of adhesive material is 3.00% and the unit area weight is 0.180 g / cm³. 2 The adhesive composition 2 prepared as described below is coated in a manner in which the bonding surfaces X and Y, excluding the "region S in which the adhesive material is densely coated", are replaced with "region T in which the adhesive material is sparsely coated" as "coating region S2". In this "coating region S2", the coverage rate of the adhesive material is 3.00% and the weight per unit area is 0.180 g / cm³. 2 The adhesive composition 1 was coated in the same manner as in Example 1. Otherwise, the adhesive composition, negative electrode material, positive electrode material, spacer material, laminate, and secondary battery were prepared and manufactured in the same manner as in Example 1.

[0379] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

[0380] <Preparation of Composition 2 for Adhesive Layer>

[0381] In the preparation of the adhesive layer composition of Example 1, instead of the aqueous dispersion of the particulate polymer 1 with a core-shell structure obtained in Manufacturing Example 1, the aqueous dispersion of the particulate polymer 2 with a core-shell structure obtained in Manufacturing Example 2 was used. Otherwise, the process was carried out in the same manner as in Example 1 to obtain adhesive composition 2.

[0382] (Example 15)

[0383] In the fabrication of the laminate in Example 1, "coating region S1" is used instead of "region S where adhesive material is densely coated". In this "coating region S1", the coverage rate of adhesive material is 3.00% and the unit area weight is 0.180 g / cm³. 2 The adhesive composition 3 prepared as described below is applied in a manner that replaces the "sparsely coated adhesive material area T" with "coating area S2" for the bonding surfaces X and Y, excluding the "region S in which the adhesive material is densely coated". In this "coating area S2", the adhesive material coverage rate is 3.00% and the unit area weight is 0.180 g / cm³. 2 The adhesive composition 1 was coated in the same manner as in Example 1. Otherwise, the adhesive composition, negative electrode material, positive electrode material, spacer material, laminate, and secondary battery were prepared and manufactured in the same manner as in Example 1.

[0384] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

[0385] <Preparation of Composition 3 for Adhesive Layer>

[0386] In the preparation of the adhesive layer composition of Example 1, instead of the aqueous dispersion of the particulate polymer 1 with a core-shell structure obtained in Manufacturing Example 1, the aqueous dispersion of the particulate polymer 3 without a core-shell structure obtained in Manufacturing Example 3 was used. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the adhesive composition 3.

[0387] (Example 16)

[0388] In the manufacture of the laminate in Example 1, the adhesive composition coated on the "region S in which the adhesive material is densely coated" and the "region T in which the adhesive material is sparsely coated" was changed from the adhesive composition 1 prepared in Manufacturing Example 1 to the adhesive composition 5 prepared as described below. Otherwise, the same procedure as in Example 1 was followed to manufacture and prepare the adhesive composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0389] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 4.

[0390] <Preparation of Composition 5 for Adhesive Layer>

[0391] In the preparation of the adhesive layer composition of Example 1, instead of the aqueous dispersion of the particulate polymer 1 with a core-shell structure obtained in Manufacturing Example 1, the aqueous dispersion of the particulate polymer 5 with a core-shell structure obtained in Manufacturing Example 5 was used. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the adhesive composition 5.

[0392] (Example 17)

[0393] In the manufacture of the laminate in Example 1, the adhesive composition coated on the "region S in which the adhesive material is densely coated" and the "region T in which the adhesive material is sparsely coated" was changed from the adhesive composition 1 prepared in Manufacturing Example 1 to the adhesive composition 6 prepared as described below. Otherwise, the same procedure as in Example 1 was followed to manufacture and prepare the adhesive composition, the negative electrode raw material, the positive electrode raw material, the spacer raw material, the laminate, and the secondary battery.

[0394] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 4.

[0395] <Preparation of Composition 6 for Adhesive Layer>

[0396] In the preparation of the adhesive layer composition of Example 1, instead of the aqueous dispersion of the particulate polymer 1 with a core-shell structure obtained in Manufacturing Example 1, the aqueous dispersion of the particulate polymer 6 with a core-shell structure obtained in Manufacturing Example 6 was used. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the adhesive composition 6.

[0397] (Comparative Example 1)

[0398] By using a gravure coating machine (51-54) instead of an inkjet coating machine, the adhesive composition 1 is applied to the entire bonding surface, resulting in a 90% coverage of the adhesive material on bonding surfaces X and Y, with a unit area weight of 0.220 g / m². 2 In addition, the same procedure as in Example 1 was followed to prepare and manufacture adhesive materials, adhesive compositions, negative electrode raw materials, positive electrode raw materials, spacer raw materials, laminates, and secondary batteries.

[0399] Then, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0400] (Comparative Example 2)

[0401] In the manufacture of the laminate in Example 1, the area of ​​the "region S in which the adhesive material is densely coated" was changed from 10% to 100% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "region T in which the adhesive material is sparsely coated" was changed from 90% to 0% of the area of ​​the bonding surfaces X and Y. Otherwise, the same procedure as in Example 1 was followed to manufacture and prepare the adhesive composition, the negative electrode raw material, the positive electrode raw material, the spacer raw material, the laminate, and the secondary battery.

[0402] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0403] (Comparative Example 3)

[0404] In the manufacture of the laminate in Example 1, the area of ​​the "region S in which the adhesive material is densely coated" was changed from 10% to 0% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "region T in which the adhesive material is sparsely coated" was changed from 90% to 100% of the area of ​​the bonding surfaces X and Y. Otherwise, the same procedure as in Example 1 was followed to manufacture and prepare the adhesive composition, the negative electrode raw material, the positive electrode raw material, the spacer raw material, the laminate, and the secondary battery.

[0405] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0406] In addition, in Tables 1-4,

[0407] "MMA" stands for methyl methacrylate.

[0408] "BA" indicates butyl acrylate.

[0409] "2EHA" represents 2-ethylhexyl acrylate.

[0410] “AN” represents acrylonitrile.

[0411] "St" represents styrene.

[0412] "MAA" stands for methacrylic acid.

[0413] "AA" indicates acrylic acid.

[0414] "AGE" stands for allyl glycidyl ether.

[0415] "AMA" stands for allyl methacrylate.

[0416] “EDMA” stands for ethylene glycol dimethacrylate.

[0417] In addition, in Table 2,

[0418] “PVdF-HFP” indicates vinylidene fluoride-hexafluoropropylene copolymer.

[0419] [Table 1]

[0420]

[0421] [Table 2]

[0422]

[0423] [Table 3]

[0424]

[0425] [Table 4]

[0426]

[0427] As shown in Tables 2, 3, and 4, the secondary batteries of Examples 1 to 17 have a stacked body formed by sequentially stacking a positive electrode, a spacer, and a negative electrode. The central region P, which has a shape similar to that of surface Z, a center at the same position as the center of surface Z, and an area of ​​10% of the area of ​​surface Z, has a resistance A per unit area greater than the resistance B per unit area of ​​the region Q of surface Z excluding the central region P. The secondary battery has excellent cycle characteristics.

[0428] On the other hand, it can be seen that in Comparative Examples 1 to 3, where the resistance A per unit area of ​​the central region P is not greater than the resistance B per unit area of ​​the region Q in the surface Z excluding the central region P, the cycle characteristics of the secondary battery are poor.

[0429] Industrial availability

[0430] According to the present invention, a secondary battery with excellent cycle characteristics can be provided.

[0431] Explanation of reference numerals in the attached figures

[0432] 10: First spacer;

[0433] 10A: Raw material for the first spacer;

[0434] 20: Negative electrode;

[0435] 20A: Anode raw material;

[0436] 21: Current collector for negative electrode;

[0437] 22, 23: Negative electrode composite material layer;

[0438] 24: First edge;

[0439] 25: Second edge;

[0440] 26: Third edge;

[0441] 27: Fourth edge;

[0442] 30: Second spacer;

[0443] 30A: Raw material for the second spacer;

[0444] 40: Positive electrode;

[0445] 41: Current collector for positive electrode;

[0446] 42, 43: Positive electrode composite material layer;

[0447] 50: Droplet;

[0448] 51-54: Coating machine (nozzle head);

[0449] 55: Nozzle;

[0450] 60: Substrate;

[0451] 61, 62: Crimping rollers;

[0452] 70: Cutting machine;

[0453] 91: Conveyor roller;

[0454] 92: Heating roller;

[0455] Z: face;

[0456] R: Center;

[0457] P: Central area;

[0458] Q: Other areas;

[0459] r: the radius of the point;

[0460] X, Y: Distance between the centers of points;

[0461] l: Line width of the coated area;

[0462] s: Spacing of coated areas (line width of uncoated areas);

[0463] S: Areas densely coated with adhesive material;

[0464] T1: Areas sparsely coated with adhesive material;

[0465] T2: Areas with a more sparse coating of adhesive material;

[0466] T3: Areas where adhesive material is applied more sparsely;

[0467] 100, 100A: Laminated bodies;

[0468] 200: Overlapping body;

[0469] 300: Particulate polymer;

[0470] 310: Core section;

[0471] 310S: The outer surface of the core;

[0472] 320: Shell.

Claims

1. A secondary battery comprising a laminate consisting of a positive electrode, a spacer, and a negative electrode stacked sequentially. Taking at least one of the contact surfaces X of the positive electrode and the spacer and Y of the negative electrode and the spacer as surface Z, the resistance A per unit area of ​​the central region P is greater than the resistance B per unit area of ​​the region Q in surface Z excluding the central region P. The central region P has a shape similar to that of the surface Z, has a center at the same location as the center of the surface Z, and has an area that is 10% of the area of ​​the surface Z. The adhesive material exists in the Z-face in a dotted or striped pattern. When the adhesive material is arranged in a dotted pattern, the coverage rate of the adhesive material in surface Z can be adjusted by changing the radius and center-to-center distance of the dots. When the adhesive material is arranged in a striped pattern, the coverage rate of the adhesive material in surface Z can be adjusted by changing the line width and the spacing of the coated portions. The coverage rate E of the adhesive material in the central region P of surface Z is greater than the coverage rate F of the adhesive material in the region Q of surface Z excluding the central region P. The swelling degree of the adhesive material in the electrolyte is above 110% and below 1500%, and the electrolyte is a solution in which LiPF6 is dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 3:

7.

2. The secondary battery according to claim 1, wherein, The coverage rate E is above 1.1% and below 30%.

3. The secondary battery according to claim 1 or 2, wherein, The coverage rate F is 0.3% or more, and the coverage rate F is less than 0.4×E.

4. The secondary battery according to claim 1 or 2, wherein, The coverage of the adhesive material in surface Z gradually decreases from the center of surface Z towards the periphery of surface Z.

5. The secondary battery according to claim 1 or 2, wherein, The adhesive material comprises a particulate polymer. The particulate polymer has a core-shell structure, which has a core and a shell that partially covers the outer surface of the core.

6. A method for manufacturing a secondary battery, comprising a stacked secondary battery having a positive electrode, a spacer, and a negative electrode sequentially stacked. The manufacturing method includes a step of coating an adhesive material onto surface Z, wherein surface Z is at least one of the bonding surface X between the positive electrode and the spacer and the bonding surface Y between the negative electrode and the spacer. The coverage rate E of the adhesive material in the central region P is greater than the coverage rate F of the adhesive material in the region Q of the surface Z excluding the central region P. The central region P has a shape similar to that of the surface Z, has a center at the same position as the center of the surface Z, and has an area of ​​10% of the area of ​​the surface Z. In the process of applying the adhesive material, the adhesive material is applied to the surface Z in a dotted or striped pattern. When the adhesive material is arranged in a dotted pattern, the coverage rate of the adhesive material in surface Z can be adjusted by changing the radius and center-to-center distance of the dots. When the adhesive material is arranged in a striped pattern, the coverage rate of the adhesive material in surface Z can be adjusted by changing the line width and the spacing of the coated portions. and then, The swelling degree of the adhesive material in the electrolyte is above 110% and below 1500%, and the electrolyte is a solution in which LiPF6 is dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 3:

7.

7. The method for manufacturing a secondary battery according to claim 6, wherein, The coverage rate E is above 1.1% and below 30%.

8. The method for manufacturing a secondary battery according to claim 6 or 7, wherein, The coverage rate F is 0.3% or more, and the coverage rate F is less than 0.4×E.

9. The method for manufacturing a secondary battery according to claim 6 or 7, wherein, The coverage of the adhesive material in surface Z gradually decreases from the center of surface Z towards the periphery of surface Z.

10. The method for manufacturing a secondary battery according to claim 6 or 7, wherein, The adhesive material comprises a particulate polymer. The particulate polymer has a core-shell structure, which has a core and a shell that partially covers the outer surface of the core.

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