Secondary batteries and their manufacturing methods

Abstract

The secondary battery of the present invention comprises a stacked body consisting of a positive electrode, a spacer, and a negative electrode stacked sequentially. When 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 is surface Z, and the length of the connecting side of either the positive electrode tab connected to the positive electrode or the negative electrode tab connected to the negative electrode is L, the resistance A per unit area of ​​region P in surface Z is greater than the resistance B per unit area of ​​region Q other than region P. Region P is a rectangular region consisting of the connecting side and a line segment 0.3L away from the connecting side as a pair of opposite sides.

Description

Technical Field

[0001] This invention relates to secondary batteries and their manufacturing methods. Background Technology

[0002] Secondary batteries, such as lithium-ion batteries, are characterized by their small size, light weight, high energy density, and ability to be repeatedly charged and discharged, and have been used in a wide range of applications. Moreover, secondary batteries typically have 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, known structures for secondary batteries include: stacked batteries, which are formed by alternately stacking positive electrodes, spacers, and negative electrodes; and wound batteries, which are formed by overlapping and rolling long strips of positive electrodes, spacers, and negative electrodes into concentric circles. Among these, stacked secondary batteries have attracted much attention in recent years due to their superior energy density, safety, quality, and durability.

[0004] Furthermore, in the manufacture of secondary batteries, processes such as manufacturing battery components with adhesive materials on their surfaces and attaching these battery components to other battery components are performed. Moreover, battery components with adhesive materials on their surfaces can be manufactured by dispersing and / or dissolving adhesive polymers (adhesive materials) in a solvent to form an adhesive composition (slurry for secondary batteries), coating it onto the surface of the battery component, and then drying it (for example, see 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 secondary batteries, metals such as lithium sometimes deposit on the electrode surfaces during charging. This is particularly true in large batteries used in automobiles, where the secondary battery has electrode tabs such as a positive electrode tab connected to the positive terminal and a negative electrode tab connected to the negative terminal. On the electrode surfaces, current concentrates around the locations where the electrode tabs connect, making it easier for metals such as lithium to deposit. Furthermore, metal deposition on the electrode surfaces of secondary batteries can lead to reduced capacity and short circuits between electrodes; therefore, it is necessary to suppress such metal deposition on the electrode surfaces.

[0010] However, there is still room for improvement in suppressing metal deposition on the electrode surface during charging for the aforementioned existing secondary batteries.

[0011] Therefore, the object of the present invention is to provide a secondary battery that can suppress metal deposition on the electrode surface during charging.

[0012] Solution for solving the problem

[0013] To achieve the aforementioned objective, the inventors conducted in-depth research. They then discovered that by making the resistance A per unit area of ​​region P in at least one of the bonding surfaces X (positive electrode and spacer) and Y (negative electrode and spacer) in surface Z larger than the resistance B per unit area of ​​region Q (excluding region P), where region P is a rectangular region with a pair of opposite sides consisting of the connecting edge of either the positive or negative electrode tab and a line segment at a predetermined distance from that connecting edge, metal deposition on the electrode surface during secondary battery charging can be suppressed, thus completing the present invention.

[0014] That is, 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 formed by sequentially stacking a positive electrode, a spacer and a negative electrode. When 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 is a surface Z, and the length of the connecting side of either the positive electrode tab connected to the positive electrode and the negative electrode tab connected to the negative electrode is L, in the surface Z, the resistance A per unit area of ​​the rectangular region P, which is a pair of opposite sides consisting of the connecting side and a line segment 0.3L away from the connecting side, is greater than the resistance B per unit area of ​​the region Q other than the region P. In this way, by making the resistance A per unit area of ​​region P (hereinafter, sometimes referred to as "region P around the electrode tab") greater than the resistance B per unit area of ​​region Q (hereinafter, sometimes referred to as "other region Q") other than region P, where region P is a rectangular region with the connecting edge of either the positive or negative electrode tab in the surface Z and a line segment at a distance specified above from the connecting edge as a pair of opposite sides, it is possible to suppress metal deposition on the electrode surface during secondary battery charging.

[0015] Furthermore, in this invention, the resistance A per unit area of ​​the region P surrounding the electrode tab and the resistance B per unit area of ​​other regions Q can be measured using the methods described in the embodiments of this specification.

[0016] In this invention, the coverage rate E of the adhesive material in region P of surface Z is preferably greater than the coverage rate F of the adhesive material in region Q. If the coverage rate E of the adhesive material in region P around the electrode tab is greater than the coverage rate F of the adhesive material in other regions Q, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed.

[0017] Furthermore, the secondary battery of the present invention preferably has a coverage rate E of 1.3% or more and 30% or less. If the coverage rate E of the adhesive material in the region P surrounding the electrode tab on surface Z is within the above-mentioned specified range, metal deposition on the electrode surface during charging of the secondary battery can be further suppressed. Furthermore, if the coverage rate E of the adhesive material in the region P surrounding the electrode tab on 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 utilize its excellent output characteristics.

[0018] Furthermore, the secondary battery of the present invention preferably has a coverage rate F of 0.5% or more and less than 0.4 × E. If the coverage rate F of the adhesive material in other regions Q of surface Z is within the above-mentioned 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 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. Using a particulate polymer with a core-shell structure as the adhesive material, with the core and shell structure having a core and a shell portion partially covering the outer surface of the core, sufficiently ensures the adhesion between the electrode and the spacer, and allows the secondary battery to fully exhibit excellent output characteristics.

[0020] 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 laminated body consisting of a positive electrode, a spacer, and a negative electrode stacked sequentially. This manufacturing method includes a step of coating an adhesive material onto surface Z, where 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. When the length of the connecting edge of either the positive electrode tab connected to the positive electrode or the negative electrode tab connected to the negative electrode is L, in surface Z, the coverage rate E of the adhesive material in a rectangular region P, where the connecting edge and a line segment 0.3L from the connecting edge form a pair of opposite sides, is greater than the coverage rate F of the adhesive material in region Q, excluding region P. Thus, according to the above-described method for manufacturing a secondary battery according to the present invention, a secondary battery capable of suppressing metal deposition on the electrode surface during charging can be obtained.

[0021] Here, in the manufacturing method of the secondary battery of the present invention, the coverage ratio E is preferably 1.3% or more and 30% or less. If the coverage ratio E of the adhesive material in the region P around the electrode tab on surface Z is within the above-mentioned specified range, metal deposition on the electrode surface during charging of the manufactured secondary battery can be further suppressed. Furthermore, if the coverage ratio E of the adhesive material in the region P around the electrode tab on surface Z is within the above-mentioned specified 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.

[0022] Furthermore, in the manufacturing method of the secondary battery of the present invention, the aforementioned coverage rate F is preferably 0.5% or more and less than 0.4 × E. If the coverage rate F of the adhesive material in other regions Q of surface Z 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 exert its excellent output characteristics.

[0023] 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. If a particulate polymer with a core-shell structure is used as the adhesive material, and the core-shell structure has a core and a shell portion partially covering the outer surface of the core, the adhesion between the electrode and the spacer can be sufficiently ensured, and the manufactured secondary battery can fully exhibit excellent output characteristics.

[0024] Invention Effects

[0025] According to the present invention, a secondary battery is provided that can suppress metal deposition on the electrode surface during charging. Attached Figure Description

[0026] Figure 1 (a) is a front view showing an example of the structure of the laminate in the secondary battery of the present invention, and (b) is an illustration. Figure 1 (a) is a top view showing the positional relationship between the negative and positive electrodes of the laminate.

[0027] 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.

[0028] Figure 3 A front view showing another example of the structure of the stacked secondary battery of the present invention.

[0029] Figure 4 This is an explanatory diagram illustrating the region P surrounding the electrode tab in surface Z.

[0030] Figure 5An illustrative diagram showing an example of a method for applying adhesive material to surface Z.

[0031] Figure 6 This is an illustrative diagram showing another example of a method for coating adhesive material on surface Z.

[0032] Figure 7 An illustrative diagram showing an example of a coating pattern for an adhesive material.

[0033] Figure 8 An illustrative diagram showing another example of a coating pattern for an adhesive material.

[0034] Figure 9 A cross-sectional view illustrating an example structure of a particulate polymer.

[0035] Figure 10 An illustrative diagram showing an example of the manufacturing process of the laminate in the secondary battery of the present invention.

[0036] Figure 11 To show Figure 10 An illustrative diagram of an example of a coating machine (nozzle head).

[0037] Figure 12 Explanatory diagrams illustrating the fabrication process of the laminates in the embodiments and comparative examples. Detailed Implementation

[0038] Hereinafter, the secondary battery and its manufacturing method according to the present invention will be described with reference to the accompanying drawings. Furthermore, in the drawings, for ease of understanding, the dimensions of some components are shown enlarged or reduced.

[0039] (Secondary battery)

[0040] The secondary battery of the present invention has at least a defined laminate and, if necessary, includes 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.

[0041] <Layered Body>

[0042] The secondary battery of the present invention has a stacked body consisting of a positive electrode, a spacer and a negative electrode stacked sequentially.

[0043] 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, for example, can be... Figure 2 The overlapping structures shown are used to form an overlapping body 200, which is used for stacked secondary batteries, etc.

[0044] like Figure 1 or Figure 3 As shown, the laminates 100 and 100A have: a negative electrode 20; a first spacer 10 attached to one side of the negative electrode; a positive electrode 40 attached to the surface of the first spacer 10 opposite to the negative electrode 20; and a second spacer 30 attached to the other side of the negative electrode 20 or to the surface of the positive electrode 40 opposite to the first spacer 10.

[0045] In addition, regarding laminates 100 and 100A, such as Figure 1 As shown in (b), the size of the positive electrode 40 in top view is smaller than the size of the negative electrode 20, the first spacer 10, and the second spacer 30 in top view. Specifically, in top view, 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 generally correspond to the cutting positions when the strip of negative electrode raw material is cut into negative electrode 20.

[0046] Here, Figure 1 (a) shows a front view of a stack 100 having: a negative electrode 20; on one side of the negative electrode ( Figure 1 The first spacer 10 is attached to the surface of the first spacer 10 (the upper part is in the middle); the side of the first spacer 10 is opposite to the side of the negative electrode 20. Figure 1 The positive electrode 40 is attached to the surface of the negative electrode 20 (located on the top side); and the second spacer 30 is attached to the surface of the negative electrode 20 on the other side. 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, the size of the positive electrode 40 in top view is smaller than the size of the negative electrode 20, the first spacer 10, and the second spacer 30, for example... Figure 1 The top view of (b) shows the positional relationship between the negative electrode 20 and the positive electrode 40. The positive electrode 40 is located between the first end edge 24 and the second end edge 25 of the negative electrode 20, which are perpendicular to the stacking direction, and is located at the negative electrode 20, perpendicular to the first end edge 24 and the second end edge 25. Figure 1 (b) Between the third end edge 26 and the fourth end edge 27 extending in the left and right directions.

[0047] 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 side of the first spacer 10. Figure 3The surface of the upper side (in the middle) replaces the surface attached to the other side of the negative electrode 20, and in addition, has the same... Figure 1 The structure is the same as that of the laminate 100 shown.

[0048] Furthermore, the laminate in the secondary battery of the present invention is not limited to Figure 1 and Figure 3 The example shown illustrates this. For instance, in a laminate, the dimensions of the first spacer 10 and the second spacer 30 in top view can also be larger than the dimensions of the negative electrode 20. If a laminate 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.

[0049] <<Surface Z, electrode tabs (positive electrode tab, negative electrode tab), area P surrounding electrode tabs>>

[0050] Surface Z is at least one of the mating surface X of the negative electrode and the spacer, and the mating surface Y of the positive electrode and the spacer. Furthermore, the positive electrode tab is connected to the positive electrode, and the negative electrode tab is connected to the negative electrode. Moreover, the length of the connecting side of either the positive electrode tab connected to the positive electrode or the negative electrode tab connected to the negative electrode is L.

[0051] Furthermore, the region P surrounding the electrode tab is a rectangular area in plane Z consisting of the connecting edge of either the positive or negative electrode tab and a line segment 0.3L away from the connecting edge as a pair of opposite sides.

[0052] Here, use Figure 4 To explain in more detail the region P around the electrode tab in surface Z.

[0053] exist Figure 4 In the above, 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] Furthermore, the positive electrode tab 44 is connected to the positive electrode 40, and the length of the connecting side of the positive electrode tab 44 is L1. Then, the negative electrode tab 28 is connected to the negative electrode 20, and the length of the connecting side of the negative electrode tab 28 is L2.

[0055] Furthermore, the aforementioned region P around the electrode tab is either (1) a rectangular region P1 (region P1 around the positive electrode tab) with the connecting edge of the positive electrode tab 44 and the line segment 0.3L1 away from the connecting edge of the positive electrode tab 44 as a pair of opposite sides, or (2) a rectangular region P2 (region P2 around the negative electrode tab) with the connecting edge of the negative electrode tab 28 and the line segment 0.3L2 away from the connecting edge of the negative electrode tab 28 as a pair of opposite sides.

[0056] Furthermore, the region P surrounding the electrode tab refers to the area around or inside the aforementioned rectangle in plane Z. Therefore, assuming that a portion of the aforementioned rectangle is located outside the periphery of plane Z, the region surrounding the electrode tab refers only to the periphery or interior of the rectangle, and the area around or inside the periphery of plane Z.

[0057] Here, the proportion of the area of ​​the region P1 surrounding the positive electrode tab alone in the total area of ​​surface Z is preferably 2.5% or more, more preferably 2.7% or more, even more preferably 3% or more, and preferably 10% or less. If the proportion of the area of ​​the region P1 surrounding the positive electrode tab alone in the total area of ​​surface Z is at or above the aforementioned lower limit, metal deposition on the electrode surface during secondary battery charging can be further suppressed. On the other hand, if the proportion of the area of ​​the region P1 surrounding the positive electrode tab alone in the total area of ​​surface Z is at or below the aforementioned upper limit, the output characteristics of the secondary battery can be improved.

[0058] Furthermore, the proportion of the area of ​​the negative electrode tab surrounding region P2 in the total area of ​​surface Z can be set to the same range as the proportion of the area of ​​the positive electrode tab surrounding region P1 in the total area of ​​surface Z.

[0059] Furthermore, the combined area of ​​the positive electrode tab surrounding region P1 and the negative electrode tab surrounding region P2 in the overall area of ​​surface Z is preferably 5% or more, more preferably 5.4% or more, even more preferably 6% or more, and preferably 20% or less. If the combined area of ​​the positive electrode tab surrounding region P1 and the negative electrode tab surrounding region P2 in the overall area of ​​surface Z is at or above the aforementioned lower limit, metal deposition on the electrode surface during secondary battery charging can be further suppressed. On the other hand, if the combined area of ​​the positive electrode tab surrounding region P1 and the negative electrode tab surrounding region P2 in the overall area of ​​surface Z is at or below the aforementioned upper limit, the output characteristics of the secondary battery can be improved.

[0060] Furthermore, the length of the connecting edge of the positive electrode tab 44 and / or the negative electrode tab 28, as well as the area of ​​surface Z, can be appropriately adjusted so that the areas of the region P1 around the positive electrode tab and / or the region P2 around the negative electrode tab meet the conditions specified above.

[0061] Here, the electrode tabs that serve as either the positive electrode tab 44 or the negative electrode tab 28 are not particularly limited, and are generally as follows: Figure 4 As shown, it is connected to the periphery of the electrode.

[0062] Furthermore, in this specification, the "connecting edge" of the electrode tab connected to the electrode refers to the boundary line between the electrode and the electrode tab as observed when the electrode is viewed from above. That is, when the electrode tab is connected to the periphery of the electrode, the connecting edge of the electrode tab is the line segment connecting the two endpoints of the portion of the periphery where the electrode tab is connected; when the electrode tab is connected to the inside of the periphery of the electrode, the connecting edge of the electrode tab is the line segment connecting the two endpoints of the portion of the periphery where it intersects with the electrode tab.

[0063] Furthermore, there are no particular limitations on the materials used to form the electrode tabs, as long as they enable the secondary battery to function properly. Materials that form the current collectors of each electrode can be used. For example, aluminum, which forms the current collector of the positive electrode, can be used for the positive electrode tab, and copper, which forms the current collector of the negative electrode, can be used for the negative electrode tab.

[0064] Furthermore, there are no particular limitations on the method for forming electrode tabs on the electrode. For example, electrode tabs can be formed by causing the material constituting the current collector in the electrode to protrude from the periphery of the electrode. More specifically, when forming an electrode composite material layer on the current collector during electrode manufacturing, an area where the electrode composite material layer is not formed can be provided at the end of the current collector, and then the area can be cut into a desired shape to form electrode tabs.

[0065] Here, regarding the configuration of the positive electrode tab 44 and the negative electrode tab 28 in the case of the top view Z, as follows: Figure 4 As shown, the positive electrode tab 44 and the negative electrode tab 28 can be disposed on the same end edge side of the rectangular surface Z, but are not limited thereto, and can also be disposed on different end edge sides of the surface Z. For example, in two opposite end edges of the rectangular surface Z, the positive electrode tab 44 is disposed on one end edge side and the negative electrode tab 28 is disposed on the other end edge side.

[0066] In addition, Figure 4 In this structure, the positive electrode 40, the negative electrode 20, and the first spacer 10 are all of the same size, so that the mating surface X of the negative electrode 20 and the mating surface Y of the positive electrode 40 and the first spacer 10 are the same. Therefore, the connecting edge of the positive electrode tab on the periphery of the mating surface X and the connecting edge of the negative electrode tab on the periphery of the mating surface Y are located on the periphery of the same surface Z when viewed from above. However, the stacked structure in the secondary battery of the present invention is not limited to this.

[0067] Furthermore, the secondary battery of the present invention is characterized in that the resistance A per unit area of ​​the region P surrounding the electrode tab is greater than the resistance B per unit area of ​​the region Q (other regions Q) in the surface Z excluding the region P surrounding the electrode tab. In this way, by making the resistance A per unit area of ​​the region P surrounding the electrode tab greater than the resistance B of the region Q in the surface Z excluding the region P surrounding the electrode tab, metal deposition on the electrode surface during secondary battery charging can be suppressed.

[0068] Furthermore, the secondary battery of the present invention may satisfy at least one of the following (i) or (ii): (i) the resistance A1 per unit area of ​​the region P1 surrounding the positive electrode tab is greater than the resistance B1 per unit area of ​​the other regions Q1 in the Z plane besides the region P1 surrounding the positive electrode tab; (ii) the resistance A2 per unit area of ​​the region P2 surrounding the negative electrode tab is greater than the resistance B2 per unit area of ​​the other regions Q2 in the Z plane besides the region P2 surrounding the negative electrode tab. Moreover, from the viewpoint of further suppressing metal deposition on the electrode surface during charging of the secondary battery, it is preferable that the secondary battery of the present invention satisfies both (i) and (ii) above.

[0069] Here, although the reason why the metal deposition on the electrode surface during secondary battery charging can be suppressed by making the resistance A per unit area of ​​the region P around the electrode tab greater than the resistance B per unit area of ​​other regions Q is unclear, it is speculated as follows.

[0070] Firstly, in secondary batteries, during charging, current flows through surface Z, and metals such as lithium tend to deposit at locations with high current density in surface Z. In conventional batteries, especially in large batteries such as those used in automobiles, where the resistance A of the region P surrounding the electrode tabs is equal to or less than the resistance B of the secondary battery, it is believed that the high current density in this region, due to its proximity to the electrode tabs responsible for power input and output, facilitates metal deposition.

[0071] In contrast, in the secondary battery of the present invention, by making the resistance A per unit area of ​​the region P surrounding the electrode tab larger than the resistance B per unit area of ​​other regions Q, the overall current density of the secondary battery during charging can be made more uniform. Therefore, it is believed that the deposition of metals such as lithium in the region P surrounding the electrode tab can be reduced. Thus, it is speculated that metal deposition on the electrode surface can be suppressed during secondary battery charging.

[0072] Furthermore, the ratio (A / B) of the resistance per unit area of ​​the region P surrounding the electrode tab to the resistance 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 per unit area of ​​the region P surrounding the electrode tab to the resistance per unit area of ​​the other region Q is greater than 1, metal deposition on the electrode surface during secondary battery charging can be sufficiently suppressed. On the other hand, if the ratio (A / B) of the resistance per unit area of ​​the region P surrounding the electrode tab to the resistance per unit area of ​​the other region Q is less than 2, the output characteristics of the secondary battery can be improved.

[0073] Furthermore, the resistance A per unit area of ​​region P surrounding the electrode tab and the resistance B per unit area of ​​other regions Q can be adjusted by factors such as the coverage of the adhesive material in each region and the type of polymer used as the adhesive material.

[0074] [Adhesive Material]

[0075] 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 spacer in surfaces X and Y. A detailed explanation of the adhesive material will follow later.

[0076] - Coating method for adhesive materials-

[0077] 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 dissolved or dispersed state, and more preferably in a dispersed state.

[0078] Furthermore, when the adhesive material is supplied to the bonding surfaces X and Y in a state of being dissolved in a solvent 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 ethyl methyl ketone and cyclohexanone; esters such as ethyl acetate, butyl acetate, γ-butyrolactone, and ε-caprolactone; nitriles such as acetonitrile and propionitrile; ethers such as tetrahydrofuran and ethylene glycol diethyl ether; and alcohols such as methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, and ethylene glycol monomethyl ether.

[0079] In the above, from the viewpoint of efficiently manufacturing laminates, a solvent containing at least one of water and alcohol is preferred as the solvent.

[0080] In addition, at least a portion of the solvent can be removed during the manufacturing process of the laminate by means of drying or the like.

[0081] Additionally, for the use of the coating machine described later ( Figure 10 and Figure 11 The coating of the adhesive material (51-54) can be performed using known coating methods such as inkjet printing, spraying, dispensing, gravure coating, and screen printing. Among these methods, inkjet printing is preferred from the viewpoint that the amount and range of the adhesive material being coated can be easily adjusted.

[0082] 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, it is preferable that the adhesive material is arranged (applied) on the bonding surfaces X and Y in a dotted pattern.

[0083] 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.

[0084] 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.

[0085] Here, the coverage of adhesive material in the "region S with densely coated adhesive material" is higher than that in the "region T with sparsely coated adhesive material".

[0086] 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 (%)].

[0087] Furthermore, in this specification, when an adhesive composition containing an adhesive material and a solvent is supplied to the bonding surface, the term "adhesive material" in "coverage of adhesive material" refers to a material in which the solvent has been removed by drying or otherwise removing the adhesive layer composition.

[0088] The shape of the "region S densely coated with adhesive material" is not particularly limited and can be appropriately set within the range that achieves the desired effect of the present invention. That is, the "region S densely coated with adhesive material" can have any shape as long as the resistance A of the region P around the electrode tab is greater than the resistance B of the secondary battery. In addition, multiple regions that exist separately within the plane Z can also be collectively referred to as a "region S densely coated with adhesive material".

[0089] 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”.

[0090] Furthermore, from the viewpoint of further suppressing metal deposition on the electrode surface during secondary battery charging, it is preferable to set the shape of the "region S in which the adhesive material is densely coated" so that the coverage rate E of the adhesive material in the region P around the electrode tab is greater than the coverage rate F of the adhesive material in other regions Q.

[0091] The region S densely coated with adhesive material preferably includes at least a portion of the aforementioned electrode tab surrounding regions P (positive electrode tab surrounding region P1 and / or negative electrode tab surrounding region P2), and more preferably includes all electrode tab surrounding regions P (positive electrode tab surrounding region P1 and / or negative electrode tab surrounding region P2).

[0092] For example, such as Figure 5 As shown, when the positive electrode tab 44 and the negative electrode tab 28 are disposed on the same end edge side of the rectangular surface Z, the area S densely coated with adhesive material can be the area between the end edge on the side where the positive electrode tab 44 and the negative electrode tab 28 are disposed and a straight line parallel to that end edge. Furthermore, in Figure 5 In the middle, the region S densely coated with adhesive material includes all of the above-mentioned positive electrode tab surrounding region P1 and negative electrode tab surrounding region P2.

[0093] In addition, for example Figure 6 As shown, in the two opposing end edges of the rectangular surface Z, with the positive electrode tab 44 disposed on one end edge and the negative electrode tab 28 disposed on the other end edge, the area S densely coated with adhesive material can be a strip-shaped area having a connecting edge connecting the positive electrode tab 44 and the connecting edge connecting the negative electrode tab 28. Furthermore, in Figure 6 In the middle, the region S densely coated with adhesive material includes all of the above-mentioned positive electrode tab surrounding region P1 and negative electrode tab surrounding region P2.

[0094] In addition, regarding Figure 5 and Figure 6The above description details the application of adhesive material to surface Z in a configuration with positive and negative electrode tabs, i.e., in a state where each electrode tab is connected to each electrode. However, the manufacturing of the laminate in the secondary battery of the present invention is not limited to this; adhesive material can also be applied to surface Z in a state where each electrode tab is not connected to each electrode. Moreover, even when adhesive material is applied to surface Z in a state where each electrode tab is not connected to each electrode, the aforementioned electrode tab surrounding region P can be set based on a predetermined configuration of the positive and negative electrode tabs. Within the range where the desired effect of the present invention can be obtained, it is preferable to apply adhesive material to surface Z in such a way that the coverage rate E of adhesive material in the electrode tab surrounding region P is greater than the coverage rate F of adhesive material in other regions Q.

[0095] Furthermore, the area of ​​the "region S densely coated with adhesive material" 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 densely coated with adhesive material" accounts for the total area of ​​surface Z within the above-mentioned range, metal deposition on the electrode surface during secondary battery charging can be further suppressed. In addition, if the area of ​​the "region S densely coated with adhesive material" accounts for the total area of ​​surface Z below the above-mentioned upper limit, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0096] Furthermore, the area of ​​the "region T sparsely coated with 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 sparsely coated with adhesive material" accounts for the area of ​​the entire surface Z within the above-mentioned range, metal deposition on the electrode surface during secondary battery charging can be further suppressed. Furthermore, if the area of ​​the "region T sparsely coated with adhesive material" accounts for the area of ​​the entire surface Z at or above the above-mentioned lower limit, sufficiently high output characteristics of the secondary battery can be ensured.

[0097] Furthermore, there is no particular limitation as long as the coverage rate J of the adhesive material in the "densely coated region S" is greater than the coverage rate K of the adhesive material in the "sparsely coated region T", preferably 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 "densely coated region S" is at or above the aforementioned lower limit, metal deposition on the electrode surface during secondary battery charging can be further suppressed. In addition, if the coverage rate J of the adhesive material in the "densely coated region S" is at or below the aforementioned upper limit, sufficiently high output characteristics of the secondary battery can be ensured.

[0098] Furthermore, there is no particular limitation as long as the coverage rate K of the adhesive material in the "sparsely coated adhesive material region T" is smaller than the coverage rate J of the adhesive material in the "densely coated adhesive material region S", preferably 0.3% or more, more preferably 0.5% or more, and preferably less than 0.4 × J%. If the coverage rate K of the adhesive material in the "sparsely coated adhesive material region T" is at or 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 "sparsely coated adhesive material region T" is less than the aforementioned upper limit, metal deposition on the electrode surface during secondary battery charging can be sufficiently suppressed.

[0099] Furthermore, the coverage rate of adhesive material in each of the regions “densely coated with adhesive material S” and “sparsely coated with adhesive material T” can be adjusted by changing the pattern of the arrangement of adhesive material in each region.

[0100] Specifically, in a certain area, when adhesive material is arranged (coated) in a dotted pattern, the coverage of adhesive material in that area can be adjusted by changing the radius and center-to-center spacing of the dots.

[0101] For example, such as Figure 7 As shown, in the region where adhesive material is applied in a dotted pattern formed by points at certain intervals along two orthogonal directions, the coverage of adhesive material can be determined using the center-to-center distance (pitch) x and y of the points and the radius r of the points by the following equation (1).

[0102] Coverage rate of adhesive material = {πr 2 / (x·y)}×100(%) …(1)

[0103] 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).

[0104] For example, such as Figure 8 As shown, in a region where the adhesive material is coated with a striped pattern with a line width of 1 for the coated portion and a spacing of s for the uncoated portion, the coverage rate of the adhesive material can be calculated by the following formula (2).

[0105] Coverage rate of adhesive material = {1 / (l+s)}×100(%) …(2)

[0106] Furthermore, the unit area mass of the adhesive material in the densely coated region S is preferably 0.02 g / m². 2 The above, preferably 0.8 g / m 2 The following is more preferably 0.35 g / m 2 The following applies: If the unit area mass 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 unit area mass 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.

[0107] Furthermore, the preferred unit area mass of the adhesive material in the sparsely coated region T is 0.02 g / m². 2 The above, more preferably 0.03 g / m 2 The above, preferably 0.35g / m 2 The following applies: If the unit area mass 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 unit area mass 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.

[0108] Furthermore, in this specification, when an adhesive composition containing an adhesive material and a solvent is supplied to the bonding surface, the term "adhesive material" in "unit area mass of adhesive material" refers to a material in which the solvent has been removed by drying or otherwise removing the adhesive layer composition.

[0109] Furthermore, in each of the aforementioned "region S in which adhesive material is densely coated" and "region T in which adhesive material is sparsely coated", adhesive material can be configured (coated) with the same pattern throughout, or adhesive materials configured (coated) with multiple different patterns can be mixed together.

[0110] Furthermore, in each region, the pattern of the adhesive material can be gradually varied along a fixed direction. For example, when the adhesive material is coated with a dotted pattern, the radius and center-to-center spacing of the dots can be gradually varied along a fixed direction; 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 be gradually varied along a fixed direction.

[0111] Furthermore, the region P surrounding the electrode tab may or may not correspond to the region S densely coated with adhesive material. Therefore, within the region P surrounding the electrode tab, there may be only a portion corresponding to the region S densely coated with adhesive material, or there may be a mixture of portions corresponding to the region S densely coated with adhesive material and portions corresponding to the region T sparsely coated with adhesive material.

[0112] Furthermore, other regions Q may or may not correspond to the “region T with sparsely coated adhesive material”. Therefore, other regions Q may contain only portions equivalent to the “region T with sparsely coated adhesive material”, or they may contain a mixture of portions equivalent to the “region S with densely coated adhesive material” and portions equivalent to the “region T with sparsely coated adhesive material”.

[0113] Here, in the case where a region U, which is either the region P surrounding the electrode tab or any other region 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 adhesive material in region U can be determined by the following equation (3).

[0114] The coverage rate of adhesive material in region U = (the coverage rate of adhesive material in region S) × (the ratio of the area of ​​region S to the total area of ​​region U) + (the coverage rate of adhesive material in region T) × (the ratio of the area of ​​region T to the total area of ​​region U)...(3)

[0115] Furthermore, the coverage rate E of the adhesive material in the preferred region P around the electrode tab is greater than the coverage rate F of the adhesive material in other regions Q.

[0116] Specifically, the coverage rate E of the adhesive material in the region P surrounding the electrode tab 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 region P surrounding the electrode tab is at or above the aforementioned lower limit, metal deposition on the electrode surface during secondary battery charging can be further suppressed. On the other hand, if the coverage rate E of the adhesive material in the region P surrounding the electrode tab is at or below the aforementioned upper limit, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0117] 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 region P surrounding the electrode tab.

[0118] Specifically, the coverage rate F of the adhesive material in other regions Q is preferably 0.5% or more, more preferably 0.7% 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 output characteristics of the secondary battery can be ensured to be sufficiently high.

[0119] Furthermore, the ratio (E / F) of the coverage rate E of the adhesive material in the region P surrounding the electrode tab to the coverage rate F of the adhesive material in other regions Q is preferably 1.5 or more, more preferably 1.8 or more, even more preferably 2.5 or more, preferably 9.0 or less, and more preferably 5.0 or less. If the ratio (E / F) of the coverage rate E of the adhesive material in the region P surrounding the electrode tab to the coverage rate F of the adhesive material in other regions Q is at or above the aforementioned lower limit, metal deposition on the electrode surface during secondary battery charging can be further suppressed. On the other hand, if the ratio (E / F) of the coverage rate E of the adhesive material in the region P surrounding the electrode tab 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.

[0120] Furthermore, the secondary battery of the present invention preferably satisfies at least one of (i) or (ii) below. From the viewpoint of further suppressing metal deposition on the electrode surface during charging of the secondary battery, it is more preferable to satisfy both (i) and (ii) below: (i) the coverage rate E1 in the region P1 surrounding the positive electrode tab is greater than the coverage rate F1 in the other region Q1 in the Z plane besides the region P1 surrounding the positive electrode tab, and (ii) the coverage rate E2 in the region P2 surrounding the negative electrode tab is greater than the coverage rate F2 in the other region Q2 in the Z plane besides the region P2 surrounding the negative electrode tab.

[0121] Furthermore, the unit area mass of the adhesive material in the region P surrounding the electrode tab is preferably 0.02 g / m². 2 The above, preferably 0.8 g / m 2 The following is more preferably 0.35 g / m 2 The following applies: If the unit area mass of the adhesive material in the region P surrounding the electrode tab is above the lower limit mentioned above, the adhesion between the electrode and the spacer can be sufficiently ensured. Furthermore, if the unit area mass of the adhesive material in the region P surrounding the electrode tab is below the upper limit mentioned above, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0122] Furthermore, the preferred unit area mass of the adhesive material in other regions Q is 0.02 g / m². 2 The above, more preferably 0.03 g / m 2 The above, preferably 0.35g / m 2 The following applies: If the unit area mass 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 unit area mass of the adhesive material in other regions Q is below the upper limit mentioned above, the output characteristics of the secondary battery can be ensured to be sufficiently high.

[0123] -Detailed description of adhesive materials-

[0124] Here, as an adhesive material, there are no particular limitations, as long as it does not hinder the battery reaction; any adhesive material used in the field of rechargeable batteries can be used. Among these, an adhesive material composed of polymers is preferred. Furthermore, the adhesive material can consist of only one type of polymer, or it can consist of two or more types.

[0125] 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 (meth)acrylate alkyl ester monomer units (acrylic polymers); polyvinyl alcohol (PVA) and other polyvinyl alcohol polymers.

[0126] In addition, in this invention, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid.

[0127] 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.

[0128] In addition, when the adhesive material made of polymer is a particulate polymer, the adhesive material of the particulate polymer can be a single-phase structure of particles formed by a single polymer, or it can be a heterogeneous structure of particles formed by physically or chemically combining two or more different polymers.

[0129] Here, specific examples of heterogeneous structures include: core-shell structures where the central part (core) and outer shell (shell) of a spherical particle are formed by different polymers; and side-by-side structures where two or more polymers are placed side by side.

[0130] Furthermore, in this invention, the "core-shell structure" includes not only a structure in which the shell completely covers the outer surface of the core, but also, for example... Figure 9 The structure shown is such that the shell partially covers the outer surface of the core.

[0131] 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 that connects the inside and outside of the shell, the shell is considered to partially cover the outer surface of the core. Therefore, for example, a particulate polymer having a shell that partially covers the outer surface of the core is considered a particulate polymer where the shell has a pore that connects the outer surface of the shell (i.e., the circumferential surface of the particulate polymer) to the outer surface of the core.

[0132] The swelling degree (hereinafter, sometimes simply referred to as "swelling degree") of the adhesive material in the electrolyte (a solution in which LiPF6 is dissolved at a concentration of 1 mol / L in a mixed solvent with a volume ratio of ethylene carbonate / diethyl carbonate = 3 / 7) 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.

[0133] In addition, the degree of swelling of the adhesive material in the electrolyte can be measured by the method described in the examples of this specification.

[0134] --Particulate polymer--

[0135] 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 particulate polymers, but it is preferable to use at least a particulate polymer with a core-shell structure, and more preferably, a combination of particulate polymers with and without a core-shell structure.

[0136] 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.

[0137] =Particulate polymers with a core-shell structure=

[0138] Core-shell structured particulate polymers are components that 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.

[0139] 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 only partially. 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, the shell is considered to partially cover the outer surface of the core.

[0140] exist Figure 9 The image shows a cross-sectional structure of an example of a particulate polymer. Figure 9 In 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 closer to the inner side than the shell portion 320. Furthermore, the shell portion 320 is the portion covering the outer surface 310S of the core portion 310, and is typically the outermost portion of the particulate polymer 300. Moreover, in... Figure 9 In the example, the shell portion 320 partially covers the outer surface 310S of the core portion 310, rather than covering the entire outer surface 310S of the core portion 310.

[0141] Furthermore, particulate polymers can have any constituent units other than the core and shell described above, as long as it does not significantly impair the desired effect. Specifically, for example, the particulate polymer may have a portion inside the core formed of a polymer different from the core. As a specific example, the seed particles used in manufacturing particulate polymers using seed polymerization may remain inside the core. However, from the viewpoint of significantly achieving the desired effect, it is preferable that the particulate polymer has only a core and a shell.

[0142] 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.

[0143] Furthermore, the glass transition temperature of the polymer in the core can be adjusted, for example, by changing the type and ratio of monomers used to prepare the polymer in the core.

[0144] 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 acrylate, 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.

[0145] In addition, in this invention, (meth)acrylic acid refers to acrylic acid and / or methacrylic acid, and (meth)acrylonitrile refers to acrylonitrile and / or methacrylonitrile.

[0146] Among these monomers, the monomers used to prepare the polymer of 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 more 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 more preferably (meth)acrylate monomer units and (meth)acrylonitrile monomer units, and even more preferably (meth)acrylate monomer units and aromatic vinyl monomer units.

[0147] In addition, in this invention, "containing monomer units" means "containing repeating units from the monomer in a polymer obtained using the monomer".

[0148] Furthermore, in this invention, "(meth)acrylate monomer" refers to a monofunctional (meth)acrylate monomer having only one polymerization reactive group.

[0149] Furthermore, from the viewpoint of making the battery components bond more firmly to each other through the adhesive material, 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.

[0150] Furthermore, when the polymer in the core contains (meth)acrylate monomer units and aromatic vinyl monomer units, from the viewpoint of making the battery components bond more firmly 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.

[0151] Furthermore, when the polymer in the core contains (meth)acrylate monomer units and (meth)acrylonitrile monomer units, from the viewpoint of making the battery components bond more firmly to each other via adhesive materials, 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] Furthermore, examples of monomers having a phosphate group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate.

[0156] In addition, in this invention, (methyl)allyl refers to allyl and / or methylallyl, and (meth)acryloyl refers to acryloyl and / or methacryloyl.

[0157] Among them, monomers containing acid groups are preferably monomers having carboxylic acid groups, and more preferably monocarboxylic acids, and more preferably (meth)acrylic acid.

[0158] In addition, acid-containing monomers can be used alone or in combination of two or more in any ratio.

[0159] 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.

[0160] 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.

[0161] 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. Di(meth)acrylate monomers are more preferred. Furthermore, these can be used alone or in combination of two or more in any ratio.

[0162] Furthermore, with all repeating units (all monomer units) contained in the polymer of the core portion as 100% by mass, the proportion of crosslinkable 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 crosslinkable monomer units within the above range, the battery components can be more firmly bonded to each other via the adhesive material.

[0163] 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 via adhesive materials.

[0164] In addition, the glass transition temperature of the polymer can be determined by the methods described in the examples of this specification.

[0165] Furthermore, the glass transition temperature of the polymer in the shell can be adjusted, for example, by changing the type and proportion of monomers used to prepare the polymer in the shell.

[0166] 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 10°C or more higher than that of the polymer in the core, more preferably 30°C or more higher, and particularly preferably 50°C or more higher.

[0167] As monomers for the polymer used to prepare the shell, examples include monomers similar to those exemplified as monomers that can be used to manufacture the polymer core. Furthermore, such monomers can be used alone or in combination of two or more in any ratio.

[0168] Among these monomers, from the viewpoint of enabling battery components to be more firmly bonded to each other via adhesive materials, aromatic vinyl monomers are preferably used as monomers for the polymer used to prepare the casing. That is, the polymer of the casing preferably contains aromatic vinyl monomer units.

[0169] Furthermore, from the viewpoint of further and more firmly bonding the battery components together in the electrolyte via adhesive materials, 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, with all repeating units (all monomer units) contained in the polymer of the shell being 100% by mass.

[0170] In addition to aromatic vinyl monomer units, the polymer in the shell portion 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 monomers that are the same as those used to form the core portion.

[0171] Among them, monomers containing acid groups are preferably monomers having carboxylic acid groups, more preferably monocarboxylic acids, and even more preferably (meth)acrylic acid.

[0172] In addition, for acid-containing monomers, one type can be used alone, or two or more types can be used in any ratio.

[0173] 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.

[0174] The mass ratio (core / shell) of the polymer in the core to the polymer in the shell of the particulate polymer with a core-shell structure 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 (core / shell) of the polymer in the core to the polymer in the shell is within the above-mentioned range, the battery components can be more firmly bonded to each other in the electrolyte by means of an adhesive material.

[0175] 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 more firmly bonded to each other by the adhesive material.

[0176] In addition, the volume average particle size of the particulate polymer can be determined by the method described in the examples of this specification.

[0177] Furthermore, the aforementioned particulate polymer with a core-shell structure can be prepared, for example, by 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 to perform staged polymerization. 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.

[0178] Therefore, the following is an example of obtaining the above-mentioned particulate polymer with a core-shell structure using a multi-stage emulsion polymerization method.

[0179] During polymerization, conventional methods can be used as emulsifiers, such as anionic surfactants like sodium dodecylbenzenesulfonate and sodium dodecyl sulfate; nonionic surfactants like polyoxyethylene nonylphenyl ether and sorbitol monolaurate; or cationic surfactants like octadecylamine acetate. Furthermore, as polymerization initiators, 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 can be used.

[0180] Furthermore, as a polymerization step, the monomers forming the core and the emulsifier are first mixed and emulsion polymerization is performed in one 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 to obtain the aforementioned particulate polymer with a core-shell structure.

[0181] In this case, when preparing a particulate polymer in which the outer surface of the core is partially covered by a shell, the monomers of the polymer forming the shell are preferably supplied 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 particles, which are bonded to the core, thereby forming a shell that partially covers the core.

[0182] =Particulate polymers without a core-shell structure=

[0183] In addition to the aforementioned particulate polymers with a core-shell structure, adhesive materials may also include particulate polymers without a core-shell structure.

[0184] 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.

[0185] 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.

[0186] From the viewpoint of making the battery components bond more firmly to each other by means of 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, further preferably 60% by mass or more, preferably 85% by mass or less, more preferably 80% by mass or less, and further preferably 75% 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.

[0187] From the viewpoint of making the battery components bond more firmly to each other by means of an adhesive material, the proportion of aromatic ethylene 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 100% by mass being 100% by mass.

[0188] 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.

[0189] From the viewpoint of making the battery components bond more firmly to each other through the adhesive material, the proportion of crosslinked monomer units in the polymer containing all repeating units (all monomer units) 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.

[0190] 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, even more preferably 200 nm or more, preferably 600 nm or less, more preferably 500 nm or less, and even more preferably 400 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 more firmly bonded to each other via the adhesive material.

[0191] 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, and known polymerization methods and polymerization reactions can be used.

[0192] -other-

[0193] The adhesive material present in region P around the aforementioned electrode tab can be the same as or different from the adhesive material present in other regions Q.

[0194] Therefore, in the aforementioned "region S with dense adhesive coating" and "region T with sparse adhesive coating", the same adhesive material can be applied, or different adhesive materials can be applied.

[0195] Furthermore, in the above-described "method for 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 in the secondary battery of the present invention is not limited to this. The adhesive material can be coated in a manner where "coating region S1" is used instead of the aforementioned "region S in which adhesive material is densely coated," and "coating region S2" is used instead of the aforementioned "region T in which adhesive material is sparsely coated." That is, the adhesive material can be coated in surface Z in a manner where "coating region S1" and "coating region S2" are present.

[0196] Here, the coverage rate and / or unit area mass of the adhesive material in each of "coating area S1" and "coating area S2" can be set within the same range as the preferred range of the coverage rate and / or unit area mass of the adhesive material in the "area S in which the adhesive material is densely coated" described above. Alternatively, the adhesive material can be coated in both "coating area S1" and "coating area S2" in the same manner with the same coverage rate and / or unit area mass.

[0197] Furthermore, the adhesive material applied in "coating region S1" is different from the adhesive material applied in "coating region S2". By appropriately selecting and using different adhesive materials as the adhesive materials applied in "coating region S1" and "coating region S2", it is possible to make the resistance A per unit area of ​​region P around the electrode tab larger than the resistance B per unit area of ​​other regions Q.

[0198] For example, as adhesive materials coated in "coating area S1" and "coating area S2", granular polymers M1 and M2 with different swelling degrees can be used.

[0199] 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 in which LiPF6 is dissolved at a concentration of 1 mol / L in a mixed solvent with a volume ratio of ethylene carbonate / diethyl carbonate = 3 / 7) is preferably 800% or more, more preferably 1000% or more, and more preferably 1300% or less.

[0200] 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 in which LiPF6 is dissolved at a concentration of 1 mol / L in a mixed solvent with a volume ratio of ethylene carbonate / diethyl carbonate = 3 / 7) is preferably 110% or more, preferably less than 800%, more preferably less than 500%, and even more preferably less than 300%.

[0201] 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 ​​region P around the electrode tab greater than the resistance B per unit area of ​​other regions Q.

[0202] Furthermore, as particulate polymers M1 and M2, particulate polymers with a core-shell structure, such as those described in the "Detailed Description of Adhesive Materials" section, 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.

[0203] Furthermore, for example, different granular polymers can be used as the adhesive materials coated in "coating area S1" and "coating area S2". More specifically, as the granular polymer M3 included in the adhesive material coated in "coating area S1", a granular polymer with a core-shell structure can be used, and as the granular polymer M4 included in the adhesive material coated in "coating area S2", a granular polymer without a core-shell structure can be used. Here, as the granular polymer M3, a granular polymer with a core-shell structure, such as that described in the "Detailed Description of Adhesive Materials" section, can be used. Furthermore, as the granular polymer M4, a granular polymer composed solely of the same polymer as the core portion of the granular polymer with a core-shell structure described in the "Detailed Description of Adhesive Materials" section can be used.

[0204] <<Methods for Manufacturing Laminated Materials>>

[0205] The method for manufacturing the laminate of 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 in step (A) does not have a positive electrode, the method further includes a step (C) of bonding a cut body obtained by cutting the bonding body in step (B) to a positive electrode. In addition, the method for manufacturing the laminate of the secondary battery of the present invention may include, in addition to the above-described steps (A), (B), and (C), a step of connecting electrode tabs (positive electrode tab and negative electrode tab) to electrodes (positive electrode and negative electrode).

[0206] [Process (A)]

[0207] Here, examples of the bonding materials prepared in process (A) are (I) and (II) below.

[0208] (I) A composite body having a strip of negative electrode raw material or negative electrode (hereinafter, “negative electrode raw material or negative electrode” is referred to as “negative electrode material”), a strip of first spacer raw material attached to one side of the negative electrode material, a strip of second spacer raw material attached to the other side of the negative electrode material, and a positive electrode arbitrarily attached to the surface of the first spacer raw material that is opposite to the negative electrode material side (hereinafter, sometimes referred to as “composite body (I)”).

[0209] (II) A composite body formed by sequentially bonding a negative electrode material made of a strip of negative electrode raw material, a strip of first spacer raw material, a positive electrode, and a strip of second spacer raw material (hereinafter, sometimes referred to as "composite body (II)").

[0210] Furthermore, in the method for manufacturing the laminate in the secondary battery of the present invention, when the bonded body (I) is prepared in step (A), typically, for example, it yields... Figure 1 The laminate shown has a negative electrode, a first spacer attached to one side 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 negative electrode on the other side.

[0211] 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.

[0212] 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), typically, for example, it yields... Figure 3 The laminate shown has a negative electrode, a first spacer attached to one side 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.

[0213] Here, the preparation of the bonded 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 bonded body together via the adhesive material. That is, step (A) includes step (a1) of applying an adhesive material to the bonding surface Y of the negative electrode material and the spacer raw material bonded to the negative electrode material, and may also include step (a2) of applying an adhesive material to the bonding surface X of the spacer raw material and the positive electrode.

[0214] Furthermore, regarding the "spacer raw material for negative electrode material bonding," when the prepared bonding body is bonding body (I), it is the first spacer raw material and the second spacer raw material; when the prepared bonding body is bonding body (II), it is the first spacer raw material. Additionally, the component coated with adhesive material can be any single component, or it can be both components bonded together.

[0215] Specifically, in process (A), for example, like Figure 10 As shown, the adhesive (I) can be prepared.

[0216] Here, in Figure 10 In this process, a strip of first spacer raw material 10A fed from the first spacer raw material roller is bonded to one side of a negative electrode material composed of a strip of negative electrode raw material 20A fed from the negative electrode raw material roller using an adhesive material supplied from the coating machine 51. Similarly, a strip of second spacer raw material 30A fed from the second spacer raw material roller is bonded to the other side of the negative electrode material composed of negative electrode raw material 20A using an adhesive material supplied from the coating machine 52. Alternatively, bonding rollers 61 and 62 can be used for bonding. Then, a positive electrode 40 is bonded to the surface of the first spacer raw material 10A opposite to the negative electrode raw material 20A side using an adhesive material supplied from the coating machine 53 at a predetermined spacing, resulting in a bonded body (I) with a positive electrode.

[0217] In addition, Figure 10 In the process, the coating machine 54 supplies adhesive material to the surface of the second spacer raw material 30A that is opposite to the negative electrode raw material 20A. The bonding body is cut between the adjacent positive electrodes 40 in the length direction to obtain a laminate. The laminates are overlapped to make an overlap body. At this time, the laminates can be well bonded to each other.

[0218] Figure 11 To show Figure 10 An illustrative diagram of an example of a coating machine (nozzle head).

[0219] exist Figure 11 In the process, droplets 50 of adhesive material are applied to the substrate 60 via nozzles 55 of coating machines 51-54.

[0220] Furthermore, the method for preparing the bond in step (A) is not limited to the examples described above; for example, Figure 10 In the process, after the bonding body is cut, the coating machine 54 can supply adhesive material to the cut body.

[0221] -Anode materials and cathode-

[0222] Here, there is no particular limitation on the electrode (negative or positive), and an electrode obtained by cutting a long strip of electrode raw material (negative or positive) can be used. Moreover, as the electrode raw material (negative or positive), the following electrode raw materials can be used: an electrode raw material composed of an electrode substrate in which an electrode composite material layer (negative or positive) is formed on one or both sides of a long strip of current collector, or an electrode raw material in which a porous film layer is further formed on the electrode composite material layer of the electrode substrate.

[0223] 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, porous membrane layer refers to a layer containing non-conductive particles, as described in Japanese Patent Application Publication No. 2013-145763.

[0224] -Spacer Raw Materials-

[0225] Furthermore, there are no particular limitations on the spacer material, and spacer materials made of, for example, a strip spacer substrate or a spacer material formed by forming a porous membrane layer on one or both sides of a strip spacer substrate can be used.

[0226] 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.

[0227] Furthermore, preferably in step (a1) of coating the adhesive material onto the bonding surface Y of the spacer raw material that is bonded to the negative electrode material, or in step (a2) of coating the adhesive material onto the bonding surface X of the spacer raw material that is bonded to the positive electrode, the adhesive material is coated onto surface Z of at least one of the bonding surfaces X and Y in such a manner that the coverage rate E of the adhesive material in the region P surrounding the electrode tab is greater than the coverage rate F of the adhesive material in other regions Q. This further suppresses metal deposition on the electrode surface during secondary battery charging.

[0228] Furthermore, as a method for coating adhesive material onto surface Z such that the coverage rate E of adhesive material in the region P surrounding the electrode tab is greater than the coverage rate F of adhesive material in other regions Q, the adhesive material coating method described in the section "Surface Z, electrode tabs (positive electrode tab, negative electrode tab), and region P surrounding the electrode tab" can be used. Moreover, the coverage rate E of adhesive material in the region P surrounding the electrode tab, 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 above in the same section.

[0229] In addition, in process (a2), adhesive material is applied to the bonding surface between the spacer raw material and the positive electrode.

[0230] Specifically, in the case of preparing a bonding body with a positive electrode in process (A) (e.g., Figure 10 In step (a), if in step (a) an adhesive body (an adhesive body without a positive electrode) is prepared by pre-coating an adhesive material at the position of the positive electrode after cutting, the adhesive material is coated on the bonding surface of the spacer raw material and the positive electrode in step (a2).

[0231] That is, for example in Figure 10 In the process, the coating machine 53 coats the bonding surfaces of the first spacer raw material 10A and the positive electrode 40 with an adhesive material.

[0232] Additionally, in process (A), for example Figure 10 As shown, adhesive material is supplied to one side of the surface of the bonded body (on...) Figure 10 The middle part is the surface of the second spacer 30A that is opposite to the negative electrode raw material 20A. The laminates are overlapped to make an overlapping body. At this time, the laminates can be well bonded to each other.

[0233] [Process (B)]

[0234] 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.

[0235] Here, the cutting machine 70 can be any cutting machine that can be used in the field of manufacturing secondary batteries, such as a cutting machine that can clamp and cut the bonded body from both sides in the thickness direction of the bonded body with a cutting blade.

[0236] 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.

[0237] [Project (C)]

[0238] In process (C), which can be performed arbitrarily, if the bonding body without a positive electrode is cut in process (B), the positive electrode is bonded to the cut body obtained by cutting the bonding body in process (B), and a laminate is obtained.

[0239] Electrolyte

[0240] 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, a lithium salt 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, and (C2F5SO2)NLi.

[0241] 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.

[0242] As for the organic solvent used in the electrolyte, there are no particular limitations as long as it can dissolve the supporting electrolyte. Preferably, 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) can be used; 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 can be used. Mixtures of these solvents can also be used. Among these, carbonates are preferred due to their high dielectric constant and wide stable potential range.

[0243] 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.

[0244] Furthermore, the concentration of electrolyte in the electrolyte can be appropriately adjusted. Additionally, known additives can be added to the electrolyte.

[0245] The secondary battery of the present invention can be manufactured, for example, by winding or folding an overlapping body obtained by overlapping layers according to the shape of the battery, placing it in a device container (battery container), injecting electrolyte into the device container, and sealing it. Alternatively, the overlapping body can be the layer itself, or multiple layers can be overlapped for manufacturing. Furthermore, the overlapping body can also be made by overlapping layers and adding 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, 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 any shape, such as coin-shaped, button-shaped, sheet-shaped, cylindrical, square, or flat.

[0246] (Manufacturing method of secondary batteries)

[0247] The manufacturing method of the secondary battery of the present invention is a method for manufacturing a secondary battery having a laminate, wherein the laminate is formed by sequentially stacking a positive electrode, a spacer, and a negative electrode. Furthermore, the manufacturing method of the secondary battery of the present invention is characterized by including a step of coating an adhesive material onto surface Z under predetermined conditions (coating step), 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.

[0248] Furthermore, according to the secondary battery manufacturing method of the present invention, it is possible to manufacture a secondary battery that can suppress metal deposition on the electrode surface during charging.

[0249] Furthermore, the manufacturing method according to the present invention enables the efficient manufacture of the secondary battery of the present invention described above.

[0250] In addition, the manufacturing method of the secondary battery of the present invention may also include other processes besides the coating process described above.

[0251] <Coating Process>

[0252] In the coating process, when 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 is surface Z, and the length of the connecting edge of either the positive electrode tab connected to the positive electrode or the negative electrode tab connected to the negative electrode is L, an adhesive material is coated on surface Z such that the coverage rate E of the adhesive material in region P (region P around the electrode tab) is greater than the coverage rate F of the adhesive material in region Q (other regions Q) of surface Z other than region P. The region P is a rectangular region in which the connecting edge of surface Z and the line segment 0.3L away from the connecting edge are a pair of opposite sides.

[0253] Furthermore, as a method for coating the adhesive material onto surface Z in such a way that the coverage rate E of the adhesive material in the region P surrounding the electrode tab is greater than the coverage rate F of the adhesive material in other regions Q, the adhesive material coating method described, for example, in the section on "secondary batteries" can be used.

[0254] Furthermore, the coverage rate E of the adhesive material in the region P surrounding the electrode tab, 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.

[0255] 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.

[0256] <Other processes>

[0257] Other processes include, for example, the lamination process, the electrode tab connection process, and the assembly process.

[0258] <<Layering Process>>

[0259] In the lamination process, after the adhesive material is coated on surface Z under the conditions specified above, the positive electrode, spacer and negative electrode are sequentially laminated to obtain the laminate.

[0260] <<Electrode Tab Connection Process>>

[0261] In the electrode tab connection process, the electrode tabs (positive electrode tab and negative electrode tab) are connected to the electrodes (positive electrode and negative electrode).

[0262] Furthermore, the method for manufacturing a laminate described in the section on "secondary battery" incorporates the aforementioned coating process, lamination process, and electrode tab connection process as part of the method for manufacturing a laminate, thereby enabling the production of a laminate.

[0263] Assembly Process

[0264] 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.

[0265] Example

[0266] The present invention will now be specifically described 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.

[0267] 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.

[0268] 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, mass per unit area of ​​the coated area, dry adhesion between the electrode and the spacer, lithium deposition rate on the negative electrode surface, and output characteristics were measured and evaluated by the following methods.

[0269] Glass transition temperature

[0270] Aqueous dispersions of the particulate polymers prepared by 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 500°C, at a heating rate of 10°C / min, under the conditions specified in JIS Z8703, to obtain a differential scanning calorimetry (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 at the first inflection point after the endothermic peak.

[0271] <Volume average particle size>

[0272] The volume average particle size of the particulate polymers prepared in each manufacturing example was determined by laser diffraction. Specifically, an aqueous dispersion solution containing particulate polymers (solid component concentration 0.1% by mass) was used as a sample. The particle size distribution (volume basis) obtained by 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 calculated from the small diameter side reached 50%, which was taken as the volume average particle size D50 (nm).

[0273] <Swelling Degree>

[0274] The aqueous dispersions of the particulate polymers prepared in each manufacturing example were dried, and approximately 0.2 g of the resulting dried material was pressed at 200°C and 5 MPa for 2 minutes to obtain a film. The obtained film was cut into 1 cm square pieces as test pieces, and the mass W2 (g) of each test piece was measured. Next, the test pieces were immersed in an electrolyte (a solution in which LiPF6 was dissolved at a concentration of 1 mol / L in a mixed solvent with a volume ratio of ethylene carbonate / diethyl carbonate = 3 / 7) at 60°C for 72 hours. Then, the test pieces were removed from the electrolyte, the mixed solvent on the surface was wiped off, and the mass W3 (g) of the test pieces was measured. The swelling degree (%) was then calculated according to the following formula.

[0275] Swelling degree (%) = W3 / W2 × 100

[0276] <Shape of adhesive material>

[0277] The shape of the adhesive material coated on the bonding surface was observed using a laser microscope (Kines Corporation, VR-3100).

[0278] <Mass per unit area of ​​adhesive material>

[0279] For each region, the mass per unit area of ​​the adhesive material is calculated by the mass difference per unit area before the adhesive composition is supplied and after the adhesive composition is supplied and dried.

[0280] <Adhesion between electrode and spacer>

[0281] 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. 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.

[0282] With the current collector side of the negative electrode facing down, attach transparent tape to the surface of the current collector side of the negative electrode. Use the transparent tape specified in JIS Z1522. Fix the transparent tape 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.

[0283] A total of six measurements were performed, and the average stress was used to determine 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.

[0284] A: Peel strength is above 1.5 N / m

[0285] B: Peel strength is above 1.0 N / m and less than 1.5 N / m

[0286] C: Peel strength is ≥0.5 N / m and <1.0 N / m

[0287] D: Peel strength less than 0.5 N / m

[0288] <Lithium deposition rate on the negative electrode surface>

[0289] The manufactured lithium-ion secondary battery was fully charged to 100% state of charge (SOC) at a constant current of 1C under an environment of -10°C. Furthermore, the fully charged secondary battery was disassembled, and the negative electrode was removed to observe the surface morphology of the negative electrode composite layer. Then, the area of ​​lithium deposited on the surface of the negative electrode composite layer was measured, and the lithium deposition rate on the negative electrode surface was calculated as (area of ​​deposited lithium / surface area of ​​the negative electrode composite layer) × 100 (%). The evaluation was then performed according to the following criteria: a lower lithium deposition rate on the negative electrode surface indicates better suppression of lithium deposition on the negative electrode surface during charging.

[0290] A: Lithium deposition rate is less than 10%.

[0291] B: Lithium deposition rate is 10% or more but less than 15%.

[0292] C: Lithium deposition rate is 15% or higher but less than 20%.

[0293] D: Lithium deposition rate is above 20%.

[0294] <Output Characteristics>

[0295] 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 a constant current method at 0.2C and 1C at -10°C, and the capacity was calculated. The discharge capacity retention rate, expressed as the ratio of capacitance (=(Capacity at 1C / Capacity at 0.2C)×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, which was evaluated according to the following criteria. A higher value indicates better output characteristics.

[0296] A: The average discharge capacity retention rate is over 80%.

[0297] B: The average discharge capacity retention rate is above 70% and below 80%.

[0298] C: The average discharge capacity retention rate is above 60% and below 70%.

[0299] D: The average discharge capacity retention rate is less than 60%.

[0300] (Manufacturing Example 1)

[0301] <Manufacturing of Particulate Polymer 1>

[0302] 100 parts of deionized water and 0.3 parts of ammonium persulfate were fed into a reactor equipped with a stirrer, the gas phase was purged with nitrogen, and the temperature was raised to 80°C. Meanwhile, in another container, 40 parts of deionized 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. Polymerization was continued until the polymerization conversion reached 95%, thereby obtaining an aqueous dispersion containing particulate polymer constituting the core. 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 acid-containing monomer was continuously fed into the aqueous dispersion for 60 minutes to continue polymerization. At a polymerization conversion of 98%, the reaction was terminated by cooling, thereby preparing an aqueous dispersion containing particulate polymer 1.

[0303] 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.

[0304] 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.

[0305] (Manufacturing Example 2)

[0306] <Manufacturing of Particulate Polymer 2>

[0307] 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. All other than this, the same procedure as in Manufacturing Example 1 was followed to prepare an aqueous dispersion of particulate polymer 2 having 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] <Manufacturing of Particulate Polymer 3>

[0309] 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.

[0310] (Manufacturing Example 4)

[0311] <Manufacturing of Particulate Polymer 4>

[0312] 90 parts of deionized water and 0.5 parts of ammonium persulfate were fed into a reactor equipped with a stirrer, the gas phase was purged with nitrogen, and the temperature was raised to 80°C. Meanwhile, in another container, 15 parts of deionized water, 1.0 part of NEOPELEX 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.

[0313] The monomer composition was continuously added to the reactor over a period of 4 hours to initiate polymerization. The reaction was carried out at 80°C during the continuous addition. After the continuous addition was completed, the mixture was stirred at 80°C for an additional 3 hours to terminate the reaction.

[0314] The obtained aqueous dispersion was cooled to 25°C, and then an aqueous sodium hydroxide solution was added to adjust the pH to 8.0. Steam was then introduced to remove unreacted monomers, yielding 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.

[0315] (Manufacturing Example 5)

[0316] 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. All other than this, the same procedure as in Manufacturing Example 1 was followed to prepare an aqueous dispersion of particulate polymer 5 having a core-shell structure. Then, various measurements were performed as in Manufacturing Example 1. The results are shown in Table 1.

[0317] (Manufacturing Example 6)

[0318] In the manufacture of the particulate polymer in Manufacturing Example 5, in a reactor equipped with a stirrer, in addition to supplying 100 parts of ion-exchanged water and 0.3 parts of ammonium persulfate, 0.03 parts of sodium dodecylbenzenesulfonate as an emulsifier were also supplied. Otherwise, the process was carried out in the same manner as in Manufacturing Example 5 to prepare an aqueous dispersion of the 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.

[0319] (Example 1)

[0320] <Preparation of Adhesive Compositions>

[0321] 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%, thus obtaining adhesive composition 1.

[0322] <Production of Anode Raw Materials>

[0323] 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 to a 5 MPa pressure vessel equipped with a stirrer. 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.

[0324] Next, 100 parts 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 and adjusted to a solids content concentration of 68%, and then further mixed at 25°C for 60 minutes. The solids content concentration was then adjusted to 62% with deionized water and further mixed at 25°C for 15 minutes. 1.5 parts of the above-mentioned aqueous dispersion containing the binder material for the negative electrode composite layer and deionized water (based on the solids content) were added to the resulting mixture, adjusting the final solids content concentration to 52%, and further mixed for 10 minutes. Under reduced pressure, the mixture was degassed to obtain a slurry composition for a secondary battery negative electrode with good flowability.

[0325] 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 a current collector) to achieve 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. Then, 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 roll press to obtain a pressed negative electrode raw material with a negative electrode composite layer thickness of 80 μm.

[0326] <Production of Positive Electrode Raw Materials>

[0327] 100 parts of LiCoO2 with a volume average particle size of 12 μm as the positive electrode active material, 2 parts of acetylene black (manufactured by Denka Co., Ltd., product name "HS-100") as the conductive material, 2 parts of polyvinylidene fluoride (manufactured by Kureha Co., Ltd., product name "#7208") as the binder (based on solid content), and N-methylpyrrolidone as the solvent were mixed to a total solid content concentration of 70%. The mixture was then stirred using a planetary mixer to obtain a slurry composition for the positive electrode of a secondary battery.

[0328] Using a corner-shaped coating machine, the obtained secondary battery positive electrode slurry composition was coated onto both sides of an aluminum foil with a thickness of 20 μm, 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. Then, it was heat-treated at 120°C for 2 minutes to obtain the positive electrode raw material.

[0329] 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.

[0330] <Preparation of spacer raw materials>

[0331] Prepare the raw materials for the spacer made of polypropylene (PP) (product name "Celgard2500").

[0332] <Fabrication of Layered Structures>

[0333] Using the prepared adhesive composition, negative electrode raw material, positive electrode raw material and spacer raw material, such as Figure 12 The layered structure is fabricated as shown. Additionally, in... Figure 12 In the figure, reference numeral 91 indicates the conveying roller, and reference numeral 92 indicates the heating roller.

[0334] Specifically, negative electrode raw material 20A, fed from the negative electrode raw material roller, is transported at a speed of 10 m / min. On one side of the negative electrode raw material 20A, an adhesive composition is supplied by the inkjet head of an inkjet coating machine 52 (Konica Corporation, KM1024 (shear mode type)). The second spacer raw material 30A, fed from the spacer raw material roller, is then bonded to the negative electrode raw material 20A via pressing rollers 61 and 62. Furthermore, on the other side of the negative electrode raw material 20A, an adhesive composition is supplied by the inkjet head of the inkjet coating machine 51 (Konica Corporation, KM1024 (shear mode type)). The laminate of the first spacer raw material 10A, fed from the spacer raw material roller, with the negative electrode raw material 20A and the second spacer raw material 30A is then bonded via pressing rollers 61 and 62. Furthermore, on the surface of the first spacer material 10A opposite to the negative electrode material 20A, an adhesive composition is supplied by the inkjet head of an inkjet coating machine 53 (Konica Corporation, KM1024 (shear mode type)). 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 by pressing rollers 61 and 62. Then, the adhesive composition is supplied to the positive electrode 40 by the inkjet head of an inkjet coating machine 54 (Konica Corporation, KM1024 (shear mode type)), and then 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. Here, portions of the current collectors of the positive electrode 40 and the negative electrode raw material 20A that do not have an electrode composite material layer (positive electrode composite material layer or negative electrode composite material layer) are punched to form tabs of a desired size, and are stacked in such a way that the positive electrode tabs and the negative electrode tabs are arranged on the same edge side of the mating surfaces X and Y (surface Z) of the electrode and the spacer.

[0335] In addition, the bonding is performed using pressing rollers 61 and 62 at a temperature of 70°C and a pressure of 1 MPa.

[0336] 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).

[0337] Here, the adhesive composition is supplied by coating machines 51-54 in the manner shown in Table 2. Specifically, the adhesive composition is applied (supplied) to each of the bonding surfaces X and Y (surface Z) of the electrode and spacer in the following manner: (1) a rectangular region N1 that completely includes a rectangular region P1 (region P1 around the positive electrode tab) that is a pair of opposite sides of the connecting edge (length L1) of the positive electrode tab 44 and a line segment 0.3L1 away from the connecting edge of the positive electrode tab 44; and (2) a rectangular region N1 that completely includes a rectangular region P1 that is a pair of opposite sides of the connecting edge (length L2) of the negative electrode tab 28 and a line segment 0.3L1 away from the connecting edge of the negative electrode tab 28. The line segment connecting the edge 0.3L2 is designated as a rectangular region P2 (the region around the negative electrode tab P2) with opposite sides. These two regions are designated as "regions S densely coated with adhesive material" in Table 2. Regions other than "regions S densely coated with adhesive material" are designated as "regions T sparsely coated with adhesive material". The "adhesive material coverage rate" in "regions S densely coated with adhesive material" is 3.0%, and the "mass 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 "mass per unit area of ​​adhesive material" is 0.044 g / m². 2Furthermore, the "adhesive material" in "coverage rate of adhesive material" and "unit area mass of adhesive material" both refer to the state in which the adhesive composition has been dried and the solvent has been removed. Here, (1) the area P1 around the positive electrode tab has 3.2% of the area of ​​the bonding surfaces X and Y (surface Z), and (2) the area P2 around the negative electrode tab has 3.2% of the area of ​​the bonding surfaces X and Y (surface Z). In addition, (1) the rectangular area N1 that completely contains the area P1 around the positive electrode tab has 5% of the area of ​​the bonding surfaces X and Y (surface Z), and (2) the rectangular area N2 that completely contains the area P2 around the negative electrode tab has 5% of the area of ​​the bonding surfaces X and Y (surface Z). Thus, the "area S densely coated with adhesive material" (i.e., the sum of the areas of (1) the rectangular area N1 and (2) the rectangular area N2) has 10% of the area of ​​the bonding surfaces X and Y (surface Z). Furthermore, as the adhesive composition used for coating, the aforementioned adhesive composition 1 is used in both the "region S in which adhesive material is densely coated" and the "region T in which adhesive material is sparsely coated". In both the "region S in which adhesive material is densely coated" and the "region T in which adhesive material is sparsely coated", the adhesive composition is coated in a dotted pattern. Additionally, observation of the dried adhesive composition (as the dried adhesive material) using a laser microscope revealed that multiple adhesive materials arranged in a tiny dotted pattern exist on the bonding surface. In both the "region S in which adhesive material is densely coated" and the "region T in which adhesive material is sparsely coated", the dot size of the adhesive material arranged in a dotted pattern is 40 μm in diameter.

[0338] As described above, the region P1 surrounding the positive electrode tab consists only of the portion equivalent to "the region S densely coated with adhesive material". Therefore, the coverage rate E of the adhesive material in the region P2 surrounding the negative electrode tab is 3.0%, and the unit area mass of the adhesive material is 0.180 g / m². 2 On the other hand, in region Q2 (other regions Q2) excluding the area P2 around the negative electrode tab, there exists a mixture of regions S (densely coated with adhesive material) and regions T (sparsely coated with adhesive material). Furthermore, the adhesive material coverage F in other regions Q2 is 0.95%, and the adhesive material's unit area mass is 0.054 g / m². 2 .

[0339] Furthermore, in a region U, there exists a portion equivalent to "region S densely coated with adhesive material" and a portion equivalent to "region T sparsely coated with adhesive material", the coverage rate and mass per unit area of ​​the adhesive material in region U can be calculated using the following formula.

[0340] (Coverage of adhesive material in region U) = (Coverage of adhesive material in densely coated region S) × (Ratio of densely coated region S in region U) + (Coverage of adhesive material in sparsely coated region T) × (Ratio of sparsely coated region T in region U)

[0341] (Mass per unit area of ​​adhesive material in region U) = (Mass per unit area of ​​adhesive material in region S densely coated with adhesive material) × (Ratio of region S densely coated with adhesive material to the entire region U) + (Mass per unit area of ​​adhesive material in region T sparsely coated with adhesive material) × (Ratio of region T sparsely coated with adhesive material to the entire region U)

[0342] The dry bond strength of the laminate was then evaluated. The results are shown in Table 2.

[0343] <Manufacturing and Resistance Measurement of Secondary Batteries>

[0344] A laminated package is made using aluminum packaging material as the outer packaging. Electrolyte (solvent: ethylene carbonate / diethyl carbonate / ethylene carbonate = 68.5 / 30 / 1.5 (volume ratio) and electrolyte (1M LiPF6 concentration) are then added. The opening of the aluminum packaging material is then sealed using a heat sealer at 150°C to manufacture a lithium-ion secondary battery. After electrolyte addition, the battery is allowed to stand at 25°C for 5 hours. Next, it is charged at 25°C using a constant current method at 0.2C to a cell voltage of 3.65V, and then aged at 60°C for 12 hours. Then, it is discharged at 25°C using a constant current method at 0.2C to a cell voltage of 3.00V. Finally, it undergoes CC-CV charging (upper limit cell voltage 4.30V) using a constant current method at 0.2C, and CC discharge to 3.00V using a constant current method at 0.2C.

[0345] Then, charge to SOC (State of Charge): 50%, and disassemble in an inactive gas environment. Extract from the area P2 surrounding the negative electrode tab of the disassembled laminate, with an effective area of ​​1 cm². 2Three electrode sets were randomly punched out, and after connecting the tab wires to each set, they were packaged in aluminum packaging material. The electrolyte was then injected to create three secondary batteries consisting only of the region P2 surrounding the negative electrode tab. The average value of the DC resistance of the batteries during discharge at a discharge rate of 3C and a discharge time of 10 seconds was taken as the resistance A2 of the region P2 surrounding the negative electrode tab. Furthermore, the "DC resistance" referred to here is the resistance value calculated using the following formula when the voltage before discharge (0 seconds) is set as V0 and the voltage after 10 seconds is set as V1.

[0346] DC resistance = 1cm 2 The current value of ×(V1-V0) / 3C

[0347] Furthermore, similarly as described above, 10 electrode groups were randomly punched out from regions Q2 (excluding the negative electrode tab area P2) of the disassembled laminate, with an effective area of ​​1cm × 1cm. A secondary battery consisting only of these other regions Q2 was then fabricated using the same method. The average DC resistance value when the battery was discharged under the same conditions as described above was taken as the resistance per unit area B2 of the other regions Q. The ratio of these resistance values ​​(A2 / B2) is shown in Table 2.

[0348] Furthermore, a stacked lithium-ion secondary battery with a capacity of 800 mAh was fabricated by overlapping five of the aforementioned laminates and pressing them at 70°C and 1 MPa for 10 seconds. This stacked body was then packaged in an aluminum outer packaging material, and an electrolyte (solvent: ethylene carbonate / diethyl carbonate / ethylene carbonate = 68.5 / 30 / 1.5 (volume ratio), electrolyte: 1M LiPF6) was injected into the aluminum outer packaging material. The opening of the aluminum outer packaging material was then sealed by heat sealing at 150°C. The lithium deposition rate and output characteristics of the resulting secondary battery on the negative electrode surface were evaluated. The results are shown in Table 2.

[0349] (Example 2)

[0350] In the manufacture of the laminate in Example 1, the adhesive composition is supplied by coating machines 51-54 in the following manner, except that it is carried out in the same manner as in Example 1, to manufacture and prepare the adhesive composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0351] Specifically, the adhesive layer composition is applied (supplied) as follows: the area between the edge of one side of the contact surfaces X and Y (surface Z) of the electrode and spacer where both the positive and negative electrode tabs are disposed and a straight line parallel to that edge is designated as "area S densely coated with adhesive material" in Table 2; the area of ​​the contact surfaces X and Y (surface Z) other than "area S densely coated with adhesive material" is designated as "area T sparsely coated with adhesive material"; the "coverage rate of adhesive material" in "area S densely coated with adhesive material" is 3.0%, and the "mass 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 "mass per unit area of ​​adhesive material" is 0.044 g / m². 2 Here, the coating is performed on an area that is 20% of the area of ​​the "area S in which the adhesive material is densely coated" having the bonding surfaces X and Y (surface Z).

[0352] By performing the coating as described above, the region P1 surrounding the positive electrode tab consists only of the portion equivalent to "the region S densely coated with adhesive material". Therefore, the coverage rate E of the adhesive material in the region P2 surrounding the negative electrode tab is 3.0%, and the unit area mass of the adhesive material is 0.180 g / m². 2 On the other hand, in region Q2 (other regions Q2) excluding the area P2 around the negative electrode tab, there exists a mixture of regions S (densely coated with adhesive material) and regions T (sparsely coated with adhesive material). Furthermore, the adhesive material coverage F in other regions Q2 is 1.17%, and the adhesive material's unit area mass is 0.068 g / m². 2 .

[0353] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0354] (Example 3)

[0355] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (middle distance) of the adhesive composition supplied in a dotted pattern to the "densely coated region S" and the "sparsely coated region T," without changing the coverage ratio of the adhesive material in each of the two regions, only the dot size of the adhesive composition supplied in a dotted pattern was changed from a diameter of 40 μm to a diameter of 80 μm. As a result, the unit area mass of the adhesive material in the "densely coated region S" is 0.124 g / m². 2 The unit area mass of the adhesive material in the "region T where the adhesive material is sparsely coated" is 0.031 g / m². 2Then, 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 and manufactured.

[0356] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0357] (Example 4)

[0358] In the manufacture of the laminate in Example 1, by adjusting the center-to-center distance (middle distance) of the adhesive composition supplied in a dotted pattern to the "densely coated region S" and the "sparsely coated region T," without changing the coverage ratio of the adhesive material in each of the two regions, only the dot size of the adhesive composition supplied in a dotted pattern was changed from a diameter of 40 μm to a diameter of 20 μm. As a result, the unit area mass of the adhesive material in the "densely coated region S" is 0.158 g / m². 2 The unit area mass of the adhesive material in the "region T where the adhesive material is sparsely coated" is 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 and manufactured.

[0359] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0360] (Example 5)

[0361] In the manufacture of the laminate in Example 1, by adjusting the center-to-center spacing (middle distance) of the adhesive composition supplied in a dotted manner to the "region T where adhesive material is sparsely coated", the coverage of the adhesive material in the "region T where adhesive material is sparsely coated" was changed from 0.79% to 0.35%, and the unit area mass of the adhesive material was changed from 0.044 g / m². 2 Change to 0.022g / m 2 Otherwise, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0362] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0363] (Example 6)

[0364] In the manufacture of the laminate in Example 1, by adjusting the center-to-center spacing (middle distance) of the adhesive composition supplied in a dotted manner to the "region T where adhesive material is sparsely coated", the coverage of the adhesive material in the "region T where adhesive material is sparsely coated" was changed from 0.79% to 0.20%, and the unit area mass of the adhesive material was changed from 0.044 g / m². 2 Change to 0.011g / m 2 Otherwise, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0365] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0366] (Example 7)

[0367] In the manufacture of the laminate in Example 1, by adjusting the center-to-center spacing (middle distance) of the adhesive composition supplied in a dotted manner to the "region T where adhesive material is sparsely coated", the coverage of the adhesive material in the "region T where adhesive material is sparsely coated" was changed from 0.79% to 1.40%, and the unit area mass of the adhesive material was changed from 0.044 g / m². 2 Change to 0.079g / m 2 Otherwise, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0368] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0369] (Example 8)

[0370] In the manufacture of the laminate in Example 1, by adjusting the center-to-center spacing (center distance) of the adhesive composition supplied in a dotted manner to the "region S densely coated with adhesive material", the coverage rate of the adhesive material in the "region S densely coated with adhesive material" was changed from 3.00% to 5.60%, and the unit area mass of the adhesive material was changed from 0.180 g / m². 2 Change to 0.316g / m 2 Otherwise, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0371] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0372] (Example 9)

[0373] In the manufacture of the laminate in Example 1, by adjusting the center-to-center spacing (center distance) of the adhesive composition supplied in a dotted manner to the "region S densely coated with adhesive material", the coverage of the adhesive material in the "region S densely coated with adhesive material" was changed from 3.00% to 12.57%, and the unit area mass of the adhesive material was changed from 0.180 g / m². 2 Change to 0.712g / m 2 Otherwise, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0374] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0375] (Example 10)

[0376] In the manufacture of the laminate in Example 1, by adjusting the center-to-center spacing (middle distance) of the adhesive composition supplied in a dotted manner to the "region S densely coated with adhesive material", the coverage rate of the adhesive material in the "region S densely coated with adhesive material" was changed from 3.00% to 1.40%, and the unit area mass of the adhesive material was changed from 0.180 g / m². 2 Change to 0.079g / m 2 Otherwise, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0377] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0378] (Example 11)

[0379] In the manufacture of the laminate in Example 1, the supply shape of the adhesive composition in the "densely coated region S" and the "sparsely coated region T" was changed from dotted to striped, the coverage of the adhesive material in the "densely coated region S" was changed from 3.00% to 9.09%, and the unit area mass 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 mass of the adhesive material was changed from 0.044 g / m². 2 Change to 0.100g / m 2 Otherwise, the same procedure as in Example 1 was followed to prepare and manufacture the bonding composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0380] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0381] (Example 12)

[0382] In the manufacture of the laminate in Example 1, the adhesive composition coated in the "region S in which the adhesive material is densely coated" and the "region T in which the adhesive material is sparsely coated" is changed from the adhesive composition 1 prepared in Manufacturing Example 1 to the adhesive composition 4 prepared as described below. Otherwise, the same procedure is followed as in Example 1 to manufacture and prepare the adhesive composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0383] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0384] <Preparation of Adhesive Composition 4>

[0385] Add 5 parts of sodium dodecylbenzenesulfonate to 100 parts of ion-exchanged water, stir using a disperser, and slowly add 10 parts of vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP; Arkema AG "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.

[0386] (Example 13)

[0387] In the manufacture of the laminate in Example 1, the area of ​​the "densely coated adhesive material region S" was changed from 10% to 50% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "sparsely coated adhesive material region T" 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, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0388] By coating as described above, the region P1 surrounding the positive electrode tab consists only of the portion equivalent to "the region S densely coated with adhesive material". Therefore, the coverage rate E of the adhesive material in the region P2 surrounding the negative electrode tab is 3.0%, and the unit area mass of the adhesive material is 0.180 g / m². 2On the other hand, in region Q2 (other regions Q2) excluding the area P2 around the negative electrode tab, there exists a mixture of regions S (densely coated with adhesive material) and regions T (sparsely coated with adhesive material). Furthermore, the adhesive material coverage F in other regions Q2 is 1.86%, and the adhesive material's unit area mass is 0.110 g / m². 2 .

[0389] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0390] (Example 14)

[0391] In the fabrication of the laminate in Example 1, "coating region S1" is used instead of "region S densely coated with adhesive material". In this "coating region S1", the coverage rate of adhesive material is 3.00% and the unit area mass is 0.180 g / cm³. 2 The adhesive composition 2 prepared as described below is coated in the following manner, and the area of ​​the bonding surfaces X and Y other than the "region S in which the adhesive material is densely coated" is designated as the "coating region S2" instead of the "region T in which the adhesive material is sparsely coated". In this "coating region S2", the coverage rate of the adhesive material is 3.00% and the unit area mass 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 raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery were prepared and manufactured in the same manner as in Example 1.

[0392] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

[0393] <Preparation of Adhesive Composition 2>

[0394] In the preparation of the adhesive layer composition of Example 1, the aqueous dispersion of the particulate polymer 2 with a core-shell structure obtained in Manufacturing Example 2 was used instead of the aqueous dispersion of the particulate polymer 1 with a core-shell structure obtained in Manufacturing Example 1. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the adhesive composition 2.

[0395] (Example 15)

[0396] In the fabrication of the laminate in Example 1, "coating region S1" is used instead of "region S densely coated with adhesive material". In this "coating region S1", the coverage rate of adhesive material is 3.00% and the unit area mass is 0.180 g / cm³. 2The adhesive composition 3 prepared as described below is coated in the following manner, and the area of ​​the bonding surfaces X and Y other than the "area S in which the adhesive material is densely coated" is designated as the "coating area S2" instead of the "area T in which the adhesive material is sparsely coated". In this "coating area S2", the coverage rate of the adhesive material is 3.00% and the unit area mass 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 raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery were prepared and manufactured in the same manner as in Example 1.

[0397] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

[0398] <Preparation of Adhesive Composition 3>

[0399] In the preparation of the adhesive layer composition of Example 1, the aqueous dispersion of the particulate polymer 3 without a core-shell structure obtained in Manufacturing Example 3 was used instead of the aqueous dispersion of the particulate polymer 1 with a core-shell structure obtained in Manufacturing Example 1. Otherwise, the same procedure as in Example 1 was followed to obtain the adhesive composition 3.

[0400] (Example 16)

[0401] In the manufacture of the laminate in Example 1, the adhesive composition coated in the "region S in which the adhesive material is densely coated" and the "region T in which the adhesive material is sparsely coated" is changed from the adhesive composition 1 prepared in Manufacturing Example 1 to the adhesive composition 5 prepared as described below. Otherwise, the same procedure is followed as in Example 1 to manufacture and prepare the adhesive composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0402] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 4.

[0403] <Preparation of Adhesive Composition 5>

[0404] In the preparation of the adhesive layer composition of Example 1, the aqueous dispersion of the particulate polymer 5 with a core-shell structure obtained in Manufacturing Example 5 was used instead of the aqueous dispersion of the particulate polymer 1 with a core-shell structure obtained in Manufacturing Example 1. Otherwise, the same procedure as in Example 1 was followed to obtain the adhesive composition 5.

[0405] (Example 17)

[0406] In the manufacture of the laminate in Example 1, the adhesive composition coated in the "region S in which the adhesive material is densely coated" and the "region T in which the adhesive material is sparsely coated" is changed from the adhesive composition 1 prepared in Manufacturing Example 1 to the adhesive composition 6 prepared as described below. Otherwise, the same procedure is followed as in Example 1 to manufacture and prepare the adhesive composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0407] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 4.

[0408] <Preparation of Adhesive Composition 6>

[0409] In the preparation of the adhesive layer composition of Example 1, the aqueous dispersion of the particulate polymer 6 with a core-shell structure obtained in Manufacturing Example 6 was used instead of the aqueous dispersion of the particulate polymer 1 with a core-shell structure obtained in Manufacturing Example 1. Otherwise, the same procedure as in Example 1 was followed to obtain the adhesive composition 6.

[0410] (Comparative Example 1)

[0411] Using a gravure coating machine (51-54) instead of an inkjet coating machine, the adhesive composition 1 is coated onto the entire bonding surface, thereby achieving a 90% coverage of the adhesive material on the entire bonding surface, with a unit area mass of 0.220 g / m². 2 Otherwise, the same procedure as in Example 1 was followed to prepare and manufacture the adhesive material, adhesive composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0412] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0413] (Comparative Example 2)

[0414] In the manufacture of the laminate in Example 2, the area of ​​the "densely coated adhesive material region S" was changed from 10% to 100% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "sparsely coated adhesive material region T" was changed from 90% to 0% of the area of ​​the bonding surfaces X and Y. Otherwise, the same procedure as in Example 2 was followed to manufacture and prepare the adhesive composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0415] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0416] (Comparative Example 3)

[0417] In the manufacture of the laminate in Example 2, the area of ​​the "densely coated adhesive material region S" was changed from 10% to 0% of the area of ​​the bonding surfaces X and Y, and the area of ​​the "sparsely coated adhesive material region T" was changed from 90% to 100% of the area of ​​the bonding surfaces X and Y. Otherwise, the same procedure as in Example 2 was followed to manufacture and prepare the adhesive composition, negative electrode raw material, positive electrode raw material, spacer raw material, laminate, and secondary battery.

[0418] Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0419] Additionally, in Tables 1-3,

[0420] "MMA" stands for methyl methacrylate.

[0421] "BA" indicates butyl acrylate.

[0422] "2EHA" represents 2-ethylhexyl acrylate.

[0423] “AN” represents acrylonitrile.

[0424] "St" represents styrene.

[0425] "MAA" stands for methacrylic acid.

[0426] "AA" indicates acrylic acid.

[0427] "AGE" stands for allyl glycidyl ether.

[0428] "AMA" stands for allyl methacrylate.

[0429] “EDMA” stands for ethylene glycol dimethacrylate.

[0430] Furthermore, in Table 2,

[0431] “PVdF-HFP” indicates vinylidene fluoride-hexafluoropropylene copolymer.

[0432] [Table 1]

[0433]

[0434] [Table 2]

[0435]

[0436] [Table 3]

[0437]

[0438] [Table 4]

[0439]

[0440] As shown in Tables 2, 3, and 4, the secondary batteries of Examples 1 to 17 have a stacked body consisting of a positive electrode, a spacer, and a negative electrode stacked sequentially. In surface Z, which is at least one of the mating surface X of the positive electrode and the spacer and the mating surface Y of the negative electrode and the spacer, the resistance A2 per unit area of ​​the rectangular region P2, which is a pair of opposite sides consisting of the connecting edge of the negative electrode tab and a line segment at a predetermined distance from the connecting edge, is greater than the resistance B2 per unit area of ​​the region Q2 other than region P2. Such a secondary battery can suppress lithium deposition on the surface of the negative electrode during charging.

[0441] On the other hand, it can be seen that the resistance A2 per unit area of ​​region P2 is not greater than the resistance B2 per unit area of ​​region Q2 other than region P2. Comparative Examples 1 to 3 are worse in suppressing lithium deposition on the negative electrode surface during secondary battery charging.

[0442] Industrial availability

[0443] According to the present invention, a secondary battery is provided that can suppress metal deposition on the electrode surface during charging.

[0444] Explanation of reference numerals in the attached figures

[0445] 10: First spacer; 70: Cutting machine

[0446] 10A: First spacer raw material; 91: Conveyor roller

[0447] 20: Negative electrode; 92: Heating roller

[0448] 20A: Negative electrode raw material Z: Surface

[0449] 21: Current collector for negative electrode; P1: Area around positive electrode tab.

[0450] 22, 23: Negative electrode composite layer P2: Area around the negative electrode tab

[0451] 24: First end edges L1, L2: Length of the connecting edge

[0452] 25: Second edge S: Area densely coated with adhesive material

[0453] 26: Third edge T: Area sparsely coated with adhesive material

[0454] 27: Fourth edge r: Radius of the point

[0455] 28: Negative electrode tab x, y: Center-to-center distance between points

[0456] 30: Second spacer l: Line width of the coated part

[0457] 30A: Second spacer material s: Spacing of coated part (line of uncoated part)

[0458] 40: Positive width)

[0459] 41: Positive electrode current collector 100, 100A: laminate

[0460] 42, 43: Positive electrode composite material layer 200: Overlapping body

[0461] 44: Positive electrode tab 300: Particulate polymer

[0462] 50: Droplet 310: Core

[0463] 51-54: Coating machine (nozzle head) 310S: Outer surface of the core

[0464] 55: Nozzle 320: Housing

[0465] 60: Substrate

[0466] 61, 62: Crimping rollers

Claims

1. A secondary battery comprising a stack of a positive electrode, a spacer, and a negative electrode sequentially stacked. When the contact surface X between the positive electrode and the spacer is surface Z, and the length of the connecting side of the positive electrode tab connected to the positive electrode is L, the connecting side of the positive electrode tab is a line segment connecting the two endpoints of the portion of the periphery of the positive electrode that intersects with the positive electrode tab, and / or, When the contact surface Y between the negative electrode and the spacer is surface Z, and the length of the connecting side of the negative electrode tab connected to the negative electrode is L, the connecting side of the negative electrode tab is a line segment connecting the two endpoints of the portion of the periphery of the negative electrode that intersects with the negative electrode tab. The resistance A per unit area of ​​region P in plane Z is greater than the resistance B per unit area of ​​region Q, excluding region P. Region P is a rectangular region defined by the connecting edge and a line segment 0.3L away from the connecting edge as a pair of opposite sides. In regions P and Q, there is an adhesive material composed of polymer.

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

3. The secondary battery according to claim 2, wherein, The coverage rate E is above 1.3% and below 30%.

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

5. The secondary battery according to any one of claims 1 to 4, 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 body having a positive electrode, a spacer, and a negative electrode sequentially stacked. The manufacturing method includes a step of coating a polymer-based adhesive material onto surface Z. When the contact surface X between the positive electrode and the spacer is surface Z, and the length of the connecting side of the positive electrode tab connected to the positive electrode is L, the connecting side of the positive electrode tab is a line segment connecting the two endpoints of the portion of the periphery of the positive electrode that intersects with the positive electrode tab, and / or, When the contact surface Y between the negative electrode and the spacer is surface Z, and the length of the connecting side of the negative electrode tab connected to the negative electrode is L, the connecting side of the negative electrode tab is a line segment connecting the two endpoints of the portion of the periphery of the negative electrode that intersects with the negative electrode tab. The coverage rate E of the adhesive material in region P of surface Z is greater than the coverage rate F of the adhesive material in region Q (excluding region P), so that the resistance A per unit area of ​​region P is greater than the resistance B per unit area of ​​region Q. Region P is a rectangular region consisting of a connecting edge and a line segment 0.3L away from the connecting edge as a pair of opposite sides. In regions P and Q, there is an adhesive material composed of polymer.

7. The method for manufacturing a secondary battery according to claim 6, wherein, The coverage rate E is above 1.3% and below 30%.

8. The method for manufacturing a secondary battery according to claim 6, wherein, The coverage rate F is greater than 0.5% and less than 0.4 × E.

9. The method for manufacturing a secondary battery according to any one of claims 6 to 8, 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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