Battery and method for manufacturing a battery

Abstract

To achieve a battery capable of obtaining high performance by suppressing the peeling between a current collector and an electrode mixture even when an electrode is thickened by increasing the amount of electrode mixture.SOLUTION: An electrode 10 is used as a positive electrode or a negative electrode of a battery, the electrode 10 including a current collector 11, having opposed main surfaces 11a, 11b and a through-hole 11c penetrating therethrough, and an electrode mixture 12 provided in both main surfaces 11a, 11b and the through-hole 11c, or in the through-hole 11c. When the thickness of the current collector 11 in a direction S in which the two opposed main surfaces 11a, 11b of the current collector 11 is denoted as d1, and the thickness of the electrode 10 in a direction S is denoted as d2, d1≤d2, d2≥150 μm, and a relationship d1 / d2≥0.2 are satisfied. Thereby, even when the electrode mixture 12 is made thick, the peeling of the electrode mixture 12 from the current collector 11 and the resulting resistance increase, etc. are suppressed, and the electrode 10 can be bent and a high-performance battery is achieved.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] A battery including an electrode having a structure in which an electrode mixture of a positive electrode or a negative electrode is laminated with a current collector such as a metal foil or a metal plate is known. For example, regarding such an electrode, a technique for forming a pattern such as a through hole for the flexibility of the electrode on the second surface of an electrode current collector having a first surface to which an electrode active material is applied and a second surface facing the first surface and to which the electrode active material is not applied is known.

[0003] Further, for a metal fiber type current collector having a conductive network structure of a non-woven fabric structure having pores in which a plurality of metal fibers are randomly arranged, an electrode is formed by infiltrating or coating an active material, and a liquid pre-electrolyte is integrated with this to form a polymer electrolyte. A technique is known.

[0004] Also, in a lithium ion secondary battery having a positive electrode current collector made of an aluminum foil having a plurality of through holes and a sulfur-based positive electrode active material, and a negative electrode current collector made of a copper foil having a plurality of through holes and a silicon-based or tin-based negative electrode active material, a technique for performing the movement of lithium ions and the doping into the negative electrode active material through the through holes of the positive and negative electrode current collectors is known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a battery equipped with electrodes containing a current collector and an electrode composite material, one method for increasing its energy density is to increase the thickness of the electrode composite material contained together with the current collector in the electrode, thereby increasing the amount of electrode composite material. However, increasing the amount of electrode composite material makes the electrode thicker and harder, and stress caused by external forces such as bending may cause delamination between the current collector and the electrode composite material. Delamination between the current collector and the electrode composite material can lead to problems such as increased resistance between them, potentially degrading the performance of the battery.

[0007] In one aspect, the present invention aims to realize a battery that can achieve high performance by suppressing the separation of the current collector and the electrode composite material, even when the amount of electrode composite material is increased and the electrodes are made thicker. [Means for solving the problem]

[0008] In one embodiment, the device includes an outer casing formed using a laminate film in which insulating layers are laminated on both main surfaces of a metal layer, and a first electrode housed in the outer casing, wherein the first electrode comprises a current collector having opposing first and second main surfaces and a through hole penetrating between the first and second main surfaces, and an electrode composite material provided within the first and second main surfaces and the through hole of the current collector, or within the through hole of the current collector, where d1 is the thickness of the current collector in a first direction in which the first and second main surfaces of the current collector face each other, and d2 is the thickness of the first electrode in the first direction, then d1 ≤ d2, d2 ≥ 150 μm, and the relationship d1 / d2 ≥ 0.2 is satisfied. The current collector has a first portion that is polygonal in plan view and is exposed from the electrode composite, the first portion is in contact with the electrode composite on two or more sides in plan view, and a first terminal is connected to the first portion. Batteries will be provided.

[0009] In one embodiment, a method for manufacturing a battery as described above is provided. [Effects of the Invention]

[0010] In one respect, it becomes possible to create a battery that can achieve high performance by increasing the amount of electrode composite material and making the electrodes thicker, while suppressing the separation between the current collector and the electrode composite material. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram illustrating an example of a battery according to an embodiment. [Figure 2] This is a diagram illustrating an example of an electrode according to an embodiment. [Figure 3] This diagram illustrates another example of an electrode. [Figure 4] This figure illustrates the adhesion between the current collector and the electrode composite material of the electrode according to the embodiment. [Figure 5] This figure illustrates a first example of a tab connection of an electrode according to an embodiment. [Figure 6] This is a diagram (part 1) illustrating an example of electrode tab connection in a comparative example. [Figure 7] This is a diagram (part 2) illustrating an example of electrode tab connection in a comparative example. [Figure 8] This is Figure (Part 3) illustrating an example of electrode tab connection in a comparative example. [Figure 9] This figure illustrates a second example of a tab connection of an electrode according to the embodiment. [Figure 10] This figure illustrates a third example of an electrode tab connection according to the embodiment. [Modes for carrying out the invention]

[0012] Figure 1 illustrates an example of a battery according to the embodiment. Figure 1(A) schematically shows a plan view of an example of a battery according to the embodiment, and Figure 1(B) schematically shows an exploded perspective view of an example of a battery according to the embodiment.

[0013] The battery 1 shown in Figures 1(A) and 1(B) is an example of a laminated battery (also called a "layered laminated battery"), which is a type of thin battery. The battery 1 comprises a positive electrode 2, a negative electrode 3, a separator 4, a positive terminal (also called a "positive tab") 5, a negative terminal (also called a "negative tab") 6, an insulating film (also called a "tab film") 7, and an outer casing 8.

[0014] For the positive electrode 2, a positive electrode material containing a positive electrode active material is used. In addition to the positive electrode active material, the positive electrode material may contain a conductive assistant, a resin component, etc. When the positive electrode material contains, in addition to the positive electrode active material, a conductive assistant, a resin component, etc., the positive electrode material is also referred to as a "positive electrode composite material". The positive electrode 2 may include a current collector such as a metal foil or a metal plate. In that case, the positive electrode composite material is provided on the current collector. Note that the details of the structure of the positive electrode 2 will be described later.

[0015] For the negative electrode 3, a negative electrode material containing a negative electrode active material is used. In addition to the negative electrode active material, the negative electrode material may contain a conductive assistant, a resin component, etc. When the negative electrode material contains, in addition to the negative electrode active material, a conductive assistant, a resin component, etc., the negative electrode material is also referred to as a "negative electrode composite material". The negative electrode 3 may include a current collector such as a metal foil or a metal plate. In that case, the negative electrode composite material is provided on the current collector. Note that the details of the structure of the negative electrode 3 will be described later.

[0016] The battery 1 can be, for example, a lithium manganese dioxide primary battery. In this case, for the positive electrode 2, a positive electrode material containing manganese dioxide (MnO2) as the positive electrode active material provided on a current collector such as stainless steel can be used. For the negative electrode 3, as the negative electrode material containing lithium (Li) as the negative electrode active material, a metal layer containing metallic lithium or a lithium aluminum alloy can be used.

[0017] The separator 4 is an intervening layer interposed between the positive electrode 2 and the negative electrode 3, which separates the positive electrode 2 and the negative electrode 3. The electrolyte is contained or held in the separator 4 which is an intervening layer. When a current collector is used for both or one of the positive electrode 2 and the negative electrode 3, the positive electrode material and the negative electrode material of each other are provided so as to face each other through the separator 4. For the separator 4, a non-woven fabric of cellulose fiber or synthetic fiber, a porous resin, a ceramic, etc. can be used.

[0018] The positive electrode tab 5 is electrically connected to the positive electrode material of the positive electrode 2. If a current collector is used for the positive electrode 2, the positive electrode tab 5 is connected to that current collector. For example, a lead member (also called a "terminal lead") such as a strip of metal foil or a metal plate may be used for the positive electrode tab 5.

[0019] The negative electrode tab 6 is electrically connected to the negative electrode material of the negative electrode 3. If a current collector is used for the negative electrode 3, the negative electrode tab 6 is connected to that current collector. Terminal leads such as strip-shaped metal foil or metal plates are used for the negative electrode tab 6.

[0020] The positive electrode 2, negative electrode 3, separator 4, positive electrode tab 5, and negative electrode tab 6 (collectively referred to as "battery elements") are wrapped in the outer film 8a of the outer casing 8 such that the tips of the positive electrode tab 5 and negative electrode tab 6 protrude. The outer film 8a can be a laminate film in which insulating layers are laminated on both main surfaces of a metal layer. For example, the outer film 8a can be a laminate film in which resin layers such as polyamide or polypropylene are laminated on both main surfaces of a metal foil such as aluminum or stainless steel.

[0021] In battery 1, for example, a battery element is sandwiched between two outer films 8a such that the tips of its positive electrode tab 5 and negative electrode tab 6 protrude. The edges of the two outer films 8a, excluding the edges on which the positive electrode tab 5 and negative electrode tab 6 protrude (also called the "tab protruding edge"), are welded together by heating and pressurizing (also called "thermocompression bonding"). An electrolyte (not shown), such as a non-aqueous electrolyte, is injected as an electrolyte through the unwelded tab protruding edge, and after depressurization impregnation, the tab protruding edge is thermocompressed.

[0022] Here, to achieve sufficient airtightness with the positive electrode tab 5 and negative electrode tab 6, whose tips protrude, interposed between the tab-protruding side edges of the two outer films 8a, a strip-shaped tab film 7 is provided, for example. For the tab film 7, a thermoplastic resin such as modified polypropylene is used, for example. The tab film 7 may be made by laminating a thermoplastic resin such as modified polypropylene on both main surfaces of a base material such as polyethylene naphthalate. The tab film 7 is interposed between the two outer films 8a that sandwich the positive electrode tab 5 and the negative electrode tab 6, and when heating and pressurizing are applied, the tab film 7 adheres to the positive electrode tab 5 and the negative electrode tab 6, and the opposing tab films 7 are welded together, as well as the tab films 7 and the outer films 8a. As a result, the tab-protruding side edges of the two outer films 8a are sealed with sufficient airtightness.

[0023] Furthermore, the sealing of the tab-protruding side edges of the two outer films 8a, where the positive electrode tab 5 and negative electrode tab 6 protrude, may be performed not only by sealing with a strip-shaped tab film 7 (tab film method), but also by sealing with a component (also called a "tab lead") to which a tab film is pre-bonded in the middle of the terminal lead (tab lead method).

[0024] Furthermore, the positive electrode tab 5 and the negative electrode tab 6 are not limited to protruding from the same side edge of the outer film 8a as described above, but may also protrude from different edges of the outer film 8a, for example, from opposing edges or adjacent edges. In other words, the direction in which the positive electrode tab 5 and the negative electrode tab 6 protrude from the outer film 8a is not limited to the same direction as described above, but may be in opposite directions or in directions that intersect each other.

[0025] The positive electrode 2 and negative electrode 3 of the above-mentioned battery 1 will be described further. Figure 2 illustrates an example of an electrode according to the embodiment. Figure 2(A) schematically shows a cross-sectional view of an example of a current collector of an electrode according to the embodiment, and Figure 2(B) schematically shows a cross-sectional view of an example of an electrode according to the embodiment.

[0026] Of the positive electrode 2 and the negative electrode 3 of the battery 1 (Fig. 1), at least one of them includes a current collector 11 as shown in Fig. 2(A), for example. A metal foil or a metal plate such as stainless steel or aluminum is used for the current collector 11. The current collector 11 is provided with at least one, for example, a plurality of through holes 11c penetrating between one main surface 11a and the other main surface 11b thereof. For the current collector 11, a metal foil or a metal plate such as stainless steel or aluminum having a porous mesh structure provided with a plurality of pores can be used. In the case of the positive electrode 2, a positive electrode mixture is provided on the current collector 11 as shown in Fig. 2(A), and in the case of the negative electrode 3, a negative electrode mixture is provided on the current collector 11 as shown in Fig. 2(A).

[0027] Here, the above positive electrode 2 or negative electrode 3 (Fig. 1) including such a current collector 11 is also referred to as an "electrode", and the positive electrode mixture or negative electrode mixture provided on the current collector 11 is also referred to as an "electrode mixture".

[0028] The electrode 10 shown in Fig. 2(B) is an example of the positive electrode 2 or the negative electrode 3 including the current collector 11 as shown in Fig. 2(A). An electrode mixture 12, which is a positive electrode mixture or a negative electrode mixture, is provided on the current collector 11 of the electrode 10. In the electrode 10 shown in Fig. 2(B), the electrode mixture 12 is provided on one main surface 11a and the other main surface 11b of the current collector 11 and in the through holes 11c penetrating between them. The electrode 10 is formed, for example, by applying the electrode mixture 12 to both main surfaces 11a, 11b of the current collector 11 having the through holes 11c and performing pressing and drying. When the thickness of the electrode 10 in the direction S in which the two main surfaces 11a, 11b of the current collector 11 face each other is d1 and the thickness of the electrode 10 in the direction S is d2 in the electrode 10 shown in Fig. 2(B), d1 < d2, and for example, it is formed so as to satisfy the relationship of d2 ≧ 150μm and d1 / d2 ≧ 0.2. Note that the thickness d2 of the electrode 10 is the thickness including the current collector 11 (thickness d1) and the electrode mixture 12.

[0029] In electrodes 10 that satisfy this relationship, even if the electrode composite material 12 is made relatively thick, that is, even if the amount of electrode composite material 12 is increased to make the electrode 10 relatively thick, the decrease in adhesion between the current collector 11 and the electrode composite material 12 is suppressed, and peeling of the electrode composite material 12 from the current collector 11 and the resulting increase in resistance are suppressed.

[0030] Here, Figure 3 illustrates another example of an electrode. Figure 3(A) schematically shows a cross-sectional view of another example of an electrode, and Figure 3(B) schematically shows a cross-sectional view of the other example of an electrode when bent.

[0031] In general, in a battery equipped with an electrode (positive electrode or negative electrode) containing a current collector and an electrode composite material (positive electrode composite material or negative electrode composite material), increasing the energy density is effective by increasing the thickness of the electrode composite material contained together with the current collector in the electrode and increasing the amount of electrode composite material.

[0032] For example, consider an electrode 100, as shown in Figure 3(A), which includes a current collector 101 and electrode composite material 102 provided on both main surfaces 101a and 101b. In such an electrode 100, if the thickness of the electrode composite material 102 provided on the current collector 101 is increased in order to increase the energy density of the battery in which it is used, the electrode 100 becomes thicker and harder. Therefore, in the case of an electrode 100 used in a battery that may be bent during use, it is possible that the adhesion between the current collector 101 and the electrode composite material 102 cannot be maintained against the stress when the electrode 100 is bent. As a result, peeling of the electrode composite material 102 from the current collector 101 may occur on the electrode 100, as shown in part P of Figure 3(B), which may cause problems such as an increase in resistance. Peeling of the electrode composite material 102 from the current collector 101 and the resulting increase in resistance may degrade the performance of the battery in which the electrode 100 is used.

[0033] Although Figures 3(A) and 3(B) show examples in which electrode composite material 102 is provided on both main surfaces 101a and 101b of the current collector 101, if the electrode composite material 102 is provided on either the main surface 101a or the main surface 101b of the current collector 101, increasing the thickness of the electrode composite material 102 may similarly cause the electrode composite material 102 to peel off from the current collector 101, resulting in increased resistance and potentially degrading the battery's performance.

[0034] In contrast, in the electrode 10 (positive electrode 2 or negative electrode 3) of the battery 1 according to the embodiment, the above configuration suppresses a decrease in adhesion between the current collector 11 and the electrode composite material 12, even if the electrode composite material 12 (positive electrode composite material or negative electrode composite material) is made relatively thick, thereby suppressing peeling of the electrode composite material 12 from the current collector 11 and the resulting increase in resistance.

[0035] Figure 4 illustrates the adhesion between the current collector and the electrode composite material of the electrode according to the embodiment. Figure 4(A) schematically shows a cross-sectional view of an example of the electrode according to the embodiment, and Figure 4(B) schematically shows a cross-sectional view of an example of the electrode according to the embodiment when bent.

[0036] In electrode 10, as shown in Figure 4(A), a current collector 11 having a through hole 11c is used, and electrode composite material 12 is provided on both main surfaces 11a, 11b and in the through hole 11c. As a result, in electrode 10, the electrode composite material 12 provided on both main surfaces 11a, 11b of the current collector 11 is connected to each other by the electrode composite material 12 provided in the through hole 11c.

[0037] In the electrode 10, the electrode composite materials 12 on both main surfaces 11a and 11b of the current collector 11 are connected to each other by the electrode composite material 12 in the through-hole 11c of the current collector 11, thereby assisting the adhesion between the current collector 11 and the electrode composite material 12. Therefore, as shown in FIG. 4(B), even when the electrode 10 is bent and used, the adhesion between the current collector 11 and the electrode composite material 12 is assisted against the stress when the electrode 10 is bent, and the peeling of the electrode composite material 12 from the current collector 11 is suppressed. In the electrode 10, even if the thickness of the electrode composite material 12 is relatively increased in order to increase the energy density of the battery 1, the connection of the electrode composite materials 12 on both main surfaces 11a and 11b by the electrode composite material 12 in the through-hole 11c of the current collector 11 and the resulting assistance of the adhesion between the current collector 11 and the electrode composite material 12 suppress the peeling of the electrode composite material 12 from the current collector 11.

[0038] Here, in the electrode 10, it is considered that as the thickness d1 of the current collector 11 increases, the length in the direction S of the through-hole 11c increases, and the strength of the above-described assistance by the electrode composite material 12 provided in the through-hole 11c also increases. As a result of experiments, when the thickness of the electrode composite material 12 is increased and the thickness d2 of the electrode 10 becomes 150 μm or more, it is found that when the ratio d1 / d2 of the thickness d1 of the current collector 11 to the thickness d2 of the electrode 10 is 0.2 or more, the peeling of the electrode composite material 12 from the current collector 11 is effectively suppressed.

[0039] In addition, in the electrode 10, when the electrode composite material 12 is provided on both main surfaces 11a and 11b together with the inside of the through-hole 11c of the current collector 11, the thickness d1 of the current collector 11 becomes thinner than the thickness d2 of the electrode 10, that is, d1 < d2, and the ratio d1 / d2 < 1. In the electrode 10, the electrode composite material 12 can also be provided only in the through-hole 11c among both main surfaces 11a and 11b and the inside of the through-hole 11c, that is, d1 = d2, and the ratio d1 / d2 = 1 may be satisfied. If the relationship of d1 ≦ d2, d2 ≧ 150 μm, and d1 / d2 ≧ 0.2 is satisfied, the peeling of the electrode composite material 12 from the current collector 11 and the resulting increase in resistance are suppressed. On the other hand, in the case of a form in which the current collector 11 comes outside the electrode composite material 12, that is, a form in which d1 > d2, it should be noted that the risk of short circuit may increase due to the corners of the current collector 11 or the like.

[0040] As described above, in the electrode 10 according to the embodiment, a current collector 11 having a through hole 11c is used, and electrode composite material 12 is provided inside the through hole 11c and on both main surfaces 11a and 11b, or electrode composite material 12 is provided only inside the through hole 11c among the through hole 11c and both main surfaces 11a and 11b. The electrode 10 is set such that the thickness d2 of the electrode 10, including the current collector 11 and the electrode composite material 12, is 150 μm or more, and the ratio d1 / d2 of the thickness d2 of the electrode 10 to the thickness d1 of the current collector 11 is 0.2 or more. By using a current collector 11 having a through hole 11c of a certain length that satisfies this thickness d1 condition, it is possible to suppress peeling of the electrode composite material 12 from the current collector 11 even when a relatively thick electrode composite material 12 is provided such that the thickness d2 of the electrode 10 is 150 μm or more. A high-performance battery 1 is realized that has an increased energy density due to the relatively thick electrode composite material 12, and an electrode 10 that can be bent while suppressing peeling of the electrode composite material 12 from the current collector 11, even if the thickness d2 is relatively thick.

[0041] Furthermore, the current collector 11 of the electrode 10 is not limited to having multiple through holes 11c as illustrated in Figures 2 and 4 above; it may also have only one through hole 11c. Even in the case of a current collector 11 with only one through hole 11c, it is possible to obtain a certain effect in suppressing the peeling of the electrode composite material 12 from the current collector 11.

[0042] Furthermore, the current collector 11 of the electrode 10 may be made of a nonwoven fabric structure using metal fibers, or any other material, as long as it has through holes 11c that penetrate between its two main surfaces 11a and 11b. The shape of the through holes 11c is not limited to a shape that extends linearly parallel to the direction S (Figure 2) as exemplified.

[0043] The electrode 10 having the configuration described above is connected to a terminal, i.e., the positive electrode tab 5 or negative electrode tab 6 (Figure 1) of the battery 1. The positive electrode tab 5 or negative electrode tab 6 is connected, for example, to the current collector 11 of the electrode 10 and the electrode composite material 12. Here, the positive electrode tab 5 or negative electrode tab 6 is also referred to as the "electrode tab" or "tab".

[0044] Figure 5 illustrates a first tab connection example of an electrode according to the embodiment. Figure 5 schematically shows a plan view of an example of an electrode according to the embodiment. The electrode 10 is provided with a rectangular portion 11d in plan view, which is exposed from the electrode composite material 12 provided on the current collector 11, as shown in Figure 5, and an electrode tab 13 (positive electrode tab 5 or negative electrode tab 6) is connected to this portion 11d. The portion 11d is formed, for example, by partially removing the electrode composite material 12 provided on the current collector 11. The electrode tab 13 is attached to the portion 11d of the current collector 11, for example, by ultrasonic welding, and is connected to the current collector 11 at the connection portion 13a.

[0045] Figures 6 to 8 illustrate examples of electrode tab connections in comparative examples. Figure 6 schematically shows a plan view of the first electrode in comparative examples, Figure 7 schematically shows a plan view of the second electrode in comparative examples, and Figure 8 schematically shows a plan view of the third electrode in comparative examples.

[0046] The electrode 100A shown in Figure 6 has a configuration in which a portion 11d exposed from the electrode material 12, i.e., a planar rectangular portion 11d where the electrode material 12 is not provided, is provided on the current collector 11 on which the electrode composite material 12 is provided, so as to protrude outward. The electrode 100B shown in Figure 7 and the electrode 100C shown in Figure 8 have a configuration in which a portion 11d exposed from the electrode composite material 12, i.e., a planar rectangular portion 11d where the electrode composite material 12 is not provided, is formed on the portion of the electrode composite material 12 provided on the current collector 11 corresponding to one side of the current collector 11. Through holes 11c as described above exist in each portion 11d of the current collector 11 of these electrodes 100A, 100B, and 100C, and electrode tabs 13 are connected to each portion 11d of the current collector 11.

[0047] When the electrode tab 13 is connected to a portion 11d of the current collector 11 that has a through hole 11c, the strength of the current collector 11 is weaker than when there is no through hole 11c, because the through hole 11c is present in that portion 11d. Therefore, when the electrode 10 is bent, the stress at the time of bending tends to concentrate on the connection portion 13a of the electrode tab 13 in portion 11d of the current collector 11. In electrodes 100A, 100B, and 100C shown in Figures 6 to 8, in a plan view, the portion 11d where the electrode composite material 12 is not provided is in contact with the electrode composite material 12 on one side 11de of that portion 11d. In electrodes 100A, 100B, and 100C equipped with a current collector 11 having such a portion 11d, the strength is reduced due to the presence of the through hole 11c, and the support of the portion 11d, which is in contact with the electrode composite material 12 on only one side 11de, is relatively weak. Therefore, the stress when the electrode tab 13 is bent tends to concentrate at the connection point 13a of the electrode tab 13 at part 11d. If the stress during bending is concentrated at the connection point 13a of the electrode tab 13, there is a risk that peeling may occur at that connection point 13a.

[0048] In contrast, in the electrode 10 according to the embodiment, as shown in Figure 5 as the first tab connection example, a rectangular portion 11d of the current collector 11 that is exposed from the electrode composite material 12 provided on the current collector 11 and where the electrode composite material 12 is not provided is provided such that, in a plan view, it is in contact with the electrode composite material 12 on two sides 11da and 11db. In the electrode 10 shown in Figure 5, the electrode tab 13 is connected to the portion 11d that is provided such that two sides 11da and 11db are in contact with the electrode composite material 12. As a result, the portion 11d of the current collector 11, which has reduced strength due to the presence of the through hole 11c, is supported by the electrode composite material 12 on its two sides 11da and 11db, and even when the electrode 10 is bent, the concentration of stress on the portion 11d of the current collector 11 is suppressed. Therefore, peeling of the connection portion 13a of the electrode tab 13 connected to the portion 11d is suppressed. Thus, in the electrode 10 shown in Figure 5, peeling of the connection portion 13a of the electrode tab 13 is suppressed, and the degradation of the performance of the battery 1 in which it is used is suppressed.

[0049] The connection of the electrode tab 13 to the electrode 10 is not limited to the example shown in Figure 5 above. Figure 9 illustrates an example of a second tab connection of an electrode according to the embodiment. Figure 9 schematically shows a plan view of an example of an electrode according to the embodiment.

[0050] For example, as shown in Figure 9, the electrode 10 may be provided on a rectangular portion 11d of the current collector 11 that is exposed from the electrode composite material 12 provided on the current collector 11 and where the electrode composite material 12 is not provided, such that in a plan view, its three sides 11da, 11db, and 11dc are in contact with the electrode composite material 12. In the electrode 10 shown in Figure 9, the electrode tab 13 is connected to the portion 11d provided in such a way that its three sides 11da, 11db, and 11dc are in contact with the electrode composite material 12. As a result, the portion 11d of the current collector 11, which has reduced strength due to the presence of the through hole 11c, is supported by the electrode composite material 12 on its three sides 11da, 11db, and 11dc, and stress concentration on the portion 11d of the current collector 11 is suppressed even when the electrode 10 is bent. Therefore, peeling of the connection portion 13a of the electrode tab 13 connected to the portion 11d is suppressed. Thus, in the electrode 10 shown in Figure 9, peeling at the connection portion 13a of the electrode tab 13 is suppressed, and therefore the performance degradation of the battery 1 in which it is used is suppressed.

[0051] Figure 10 is a diagram illustrating a third tab connection example of the electrode according to the embodiment. Figure 10 schematically shows a plan view of an example of the electrode according to the embodiment. For example, as shown in Figure 10, the electrode 10 may be provided in a rectangular portion 11d of the current collector 11 that is exposed from the electrode composite material 12 provided on the current collector 11 and where the electrode composite material 12 is not provided, so that in a plan view, its four sides 11da, 11db, 11dc, and 11dd are in contact with the electrode composite material 12. In the electrode 10 shown in Figure 10, the electrode tab 13 is connected to the portion 11d in which its four sides 11da, 11db, 11dc, and 11dd are in contact with the electrode composite material 12. As a result, the portion 11d of the current collector 11, which has reduced strength due to the presence of the through hole 11c, is supported by the electrode composite material 12 on its four sides 11da, 11db, 11dc, and 11dd, and stress concentration on the portion 11d of the current collector 11 is suppressed even when the electrode 10 is bent. Therefore, peeling of the connection portion 13a of the electrode tab 13 connected to part 11d is suppressed. In this way, with the electrode 10 shown in Figure 10, peeling of the connection portion 13a of the electrode tab 13 is suppressed, and thus the deterioration of the performance of the battery 1 in which it is used is suppressed.

[0052] Here, an example is shown in which the planar shape of the portion 11d of the current collector 11 that is exposed from the electrode composite material 12 is rectangular. However, the planar shape of portion 11d is not limited to a rectangle, but can be any polygon (in addition to a quadrilateral, it can be a triangle or a pentagon or more). Following the example above, by providing the current collector 11 with various polygonal portions 11d so that they are in contact with the electrode composite material 12 on two or more sides, it is possible to suppress peeling at the connection portion 13a of the electrode tab 13 that is connected to portion 11d.

[0053] The embodiments have been described above. In the above description of the embodiment, an example was shown in which the electrode 10 having the above configuration is applied to at least one of the positive electrode 2 and negative electrode 3 of a single-layer battery 1 (Figure 1) which includes one positive electrode 2 and one negative electrode 3. In addition, the electrode 10 having the above configuration is not limited to a single-layer battery 1, but can also be applied to at least one or both of the groups of positive electrodes 2 and groups of negative electrodes 3 of a multilayer battery which includes multiple positive electrodes 2 and multiple negative electrodes 3.

[0054] The electrode 10 having the above configuration can be applied, for example, to the positive electrode of various lithium primary batteries that use metallic lithium or the like as the negative electrode material. For example, the electrode 10 can be applied to the positive electrode of a manganese dioxide lithium primary battery that uses manganese dioxide as the positive electrode material, a graphite fluoride lithium primary battery that uses graphite fluoride as the positive electrode material, a lithium iron sulfide primary battery that uses iron sulfide as the positive electrode material, and a copper oxide lithium primary battery that uses copper oxide as the positive electrode material.

[0055] In addition, the electrode 10 having the above configuration can also be applied to the positive electrode of a lithium secondary battery using lithium or the like as the negative electrode material and manganese dioxide or the like as the positive electrode material, the positive electrode of a lithium-ion secondary battery using graphite or the like as the negative electrode material and lithium cobalt oxide or the like as the positive electrode material, or the positive and negative electrode of an electric double-layer capacitor.

[0056] The electrode 10 having the above configuration can also be applied to the positive or negative electrode of a solid-state battery, which is a form of lithium-ion secondary battery. In a solid-state battery, for example, a solid electrolyte layer is interposed between the positive electrode and the negative electrode as an intervening layer. The positive electrode, the negative electrode, and the solid electrolyte layer interposed between them are housed in an outer casing, for example, an outer casing made of an outer film. For the solid electrolyte layer of a solid-state battery, for example, an oxide-based or sulfide-based solid electrolyte is used. For the positive electrode of a solid-state battery, a positive electrode material containing a positive electrode active material is used, and the positive electrode material may include a positive electrode composite material containing a conductive additive, resin components, solid electrolyte, etc., in addition to the positive electrode active material. For the negative electrode of a solid-state battery, for example, a negative electrode material containing a negative electrode active material is used, and the negative electrode material may include a negative electrode composite material containing a conductive additive, resin components, solid electrolyte, etc., in addition to the negative electrode active material. The electrode 10 having the above configuration can be applied to the positive or negative electrode of such a solid-state battery. Furthermore, a polymer electrolyte may be used as the intervening layer between the positive and negative electrodes of the solid-state battery. Also, metallic lithium, lithium-aluminum alloy, carbon material, etc., may be used for the negative electrode of the solid-state battery.

[0057] Examples and comparative examples of the electrode 10 according to the embodiment described above are described below. [Example 1] A laminated battery (thin battery) was prepared, in which a battery element including a positive electrode, a negative electrode, and a separator interposed between them was housed in an outer casing made of an outer film, along with a non-aqueous electrolyte, so that the tips of the positive electrode tab and negative electrode tab, which are connected to the positive electrode and negative electrode, respectively, protrude.

[0058] (Positive electrode) A positive electrode composite material was prepared with a composition containing 91 parts by weight of manganese dioxide as the positive electrode active material, 5 parts by weight of acetylene black as a conductive additive, 3.7 parts by weight of polytetrafluoroethylene (PTFE) as a binder, and 0.3 parts by weight of boron. This composite material was applied to both main surfaces of a porous mesh structure current collector made of 150 μm thick stainless steel (SUS304) so ​​that the thickness of the positive electrode after pressing would be 360 ​​μm. The material was then dried and pressed. The thickness of the positive electrode includes the thickness of the current collector and the positive electrode composite material. After drying and pressing, a 20 mm × 20 mm flat section was cut out, and a portion of the positive electrode composite material was removed in a 3 mm × 3 mm flat section to expose the current collector. The removal of the positive electrode composite material was carried out according to the example in Figure 5 above, so that, in a plan view, two sides of the area where the positive electrode composite material was not provided were in contact with the positive electrode composite material. Then, a stainless steel positive electrode tab was attached to the exposed part of the current collector, which had been created by removing the positive electrode composite material, using ultrasonic welding.

[0059] (Negative electrode) A piece of metallic lithium was cut to a flat size of 19mm x 19mm, and a stainless steel negative electrode tab was attached to it by ultrasonic welding.

[0060] (Separator) A cellulose separator with a thickness of 50 μm was used. (Battery construction) A laminate was formed by stacking a positive electrode, a separator, and a negative electrode in that order. The formed laminate was then housed in an outer casing made of laminate film (aluminum laminate film), into which a non-aqueous electrolyte was injected, followed by vacuum impregnation and then vacuum sealing. The sealing width (welding width or heat-sealing width) of the laminate film was set to 2 mm, and all four sides were sealed using a 180°C heat bar to fabricate the battery.

[0061] (Battery evaluation) The fabricated batteries were molded into a card shape using resin, and then subjected to a bending test 1000 times in total, by bending one side (front and back) and the other side (front and back) 250 times each, under conditions compliant with JIS X6305-1. The resistance (impedance) at 1 kHz was measured before and after the bending test.

[0062] [Example 2] Except for setting the thickness of the positive electrode to 200 μm, a battery was fabricated in the same manner as in Example 1, and a bending test was performed.

[0063] [Example 3] Except for setting the thickness of the positive electrode to 750 μm, a battery was fabricated in the same manner as in Example 1, and a bending test was performed.

[0064] [Example 4] A battery was fabricated in the same manner as in Example 1, except that the thickness of the positive electrode was set to 150 μm, and a bending test was performed.

[0065] [Comparative Example 1] Except for setting the thickness of the positive electrode to 850 μm, a battery was fabricated in the same manner as in Example 1, and a bending test was performed.

[0066] [Comparative Example 2] A battery was fabricated in the same manner as in Example 1, except that a 30 μm thick aluminum plain foil was used as the current collector, a positive electrode composite material was formed on one side thereof, and the thickness of the positive electrode was set to 100 μm. A bending test was then performed.

[0067] [Comparative Example 3] A battery was fabricated in the same manner as in Example 1, except that a 10 μm thick stainless steel plain foil was used as the current collector, a positive electrode composite material was formed on one side thereof, and the thickness of the positive electrode was set to 100 μm. A bending test was then performed.

[0068] [Comparative Example 4] A battery was fabricated in the same manner as in Example 1, except that a 30 μm thick perforated aluminum foil was used as the current collector and the thickness of the positive electrode was set to 200 μm, and a bending test was performed.

[0069] [Comparative Example 5] A battery was fabricated in the same manner as in Example 1, except that a 10 μm thick aluminum plain foil was used as the current collector, a positive electrode composite material was formed on one side thereof, and the thickness of the positive electrode was set to 360 μm. A bending test was then performed.

[0070] Table 1 shows the battery configurations and bending test results for Examples 1-4 and Comparative Examples 1-5.

[0071] [Table 1]

[0072] In Table 1, when the current collector of the positive electrode is a porous mesh structure made of stainless steel (Examples 1-4 and Comparative Example 1), the "Current Collector Type" is set to "Stainless Steel / Mesh" and the "Through Hole" is set to "Yes". When the current collector of the positive electrode is a plain foil made of aluminum (Comparative Examples 2 and 5), the "Current Collector Type" is set to "Aluminum / Plain" and the "Through Hole" is set to "No". When the current collector of the positive electrode is a plain foil made of stainless steel (Comparative Example 3), the "Current Collector Type" is set to "Stainless Steel / Plain" and the "Through Hole" is set to "No". When the current collector of the positive electrode is a perforated foil made of aluminum (Comparative Example 4), the "Current Collector Type" is set to "Aluminum / Perforated" and the "Through Hole" is set to "Yes".

[0073] In Table 1, "Current Collector Thickness" represents the thickness [μm] of the current collector of the positive electrode, "Electrode Thickness" represents the thickness [μm] of the positive electrode including the current collector and the positive electrode composite material, and "Ratio" represents the ratio [-] of "Current Collector Thickness" to "Electrode Thickness" (=current collector thickness / electrode thickness).

[0074] In Table 1, "Initial Resistance" represents the resistance [Ω] measured before the bending test, and "Resistance After Bending Test" represents the resistance [Ω] measured after the bending test. In Table 1, "Discharge Capacity" represents the discharge capacity [mAh] measured in the fabricated battery, and "Volumetric Energy Density" represents the volumetric energy density [mWh / cm²] measured for the fabricated battery. 3 This represents ].

[0075] Table 1 shows that when the electrode thickness of the positive electrode is less than 150 μm (Comparative Examples 2 and 3), the increase in resistance from the initial resistance after the bending test is kept relatively small, regardless of the type of current collector, the thickness of the current collector, and the ratio of the current collector thickness to the electrode thickness. However, when the electrode thickness of the positive electrode is less than 150 μm, the discharge capacity and volumetric energy density are relatively low.

[0076] Table 1 shows that when the electrode thickness of the positive electrode is 150 μm or more (Examples 1-4 and Comparative Examples 1, 4, 5), if the current collector has through holes and the ratio of the current collector thickness to the electrode thickness of the positive electrode is 0.2 or more (Examples 1-4), the resistance increase from the initial resistance after the bending test is kept relatively small. Furthermore, if the current collector has through holes and the ratio of the current collector thickness to the electrode thickness of the positive electrode is 0.2 or more (Examples 1-4), the resistance increase from the initial resistance after the bending test is kept relatively small, and relatively high discharge capacity and volumetric energy density can be obtained. When the electrode thickness of the positive electrode is 150 μm or more, by providing through holes in the current collector and setting the ratio of the current collector thickness to the electrode thickness of the positive electrode to 0.2 or more, 200 mWh / cm² can be obtained. 3 This makes it possible to achieve the above relatively high volumetric energy density.

[0077] [Comparative Example 6] In accordance with the example in Figure 6 above, a 3mm x 3mm section without a positive electrode composite material was provided on the current collector, protruding outward from the 20mm x 20mm section where the positive electrode composite material is provided. The positive electrode tab was then connected to this section by ultrasonic welding. Otherwise, a battery was manufactured in the same manner as in Example 1, and a bending test was performed.

[0078] [Comparative Example 7] Following the example in Figure 7 above, the positive electrode was cut out to a planar size of 20 mm x 20 mm, then one side of the positive electrode composite material was removed to a planar size of 3 mm x 20 mm, and the positive electrode tab was connected to the exposed current collector portion by ultrasonic welding. Otherwise, the battery was manufactured in the same manner as in Example 1, and a bending test was performed.

[0079] [Comparative Example 8] Following the example in Figure 8 above, the positive electrode was cut out to a planar size of 20 mm x 20 mm, then a 3 mm x 20 mm section of the positive electrode composite material was removed from one side, and the positive electrode tab was connected to the exposed current collector portion by ultrasonic welding. Otherwise, the battery was manufactured in the same manner as in Example 1, and a bending test was performed.

[0080] [Example 5] Following the example in Figure 9 above, the positive electrode was cut out to a planar size of 20 mm x 20 mm, and then the positive electrode composite material in the center of one side was removed to a planar size of 3 mm x 3 mm. The positive electrode tab was then attached to the exposed current collector portion by ultrasonic welding. Otherwise, the battery was manufactured in the same manner as in Example 1, and a bending test was performed.

[0081] [Example 6] Following the example in Figure 10 above, the positive electrode was cut out to a planar size of 20 mm x 20 mm. Then, the positive electrode composite material in the central part of one side, inside the edge, was removed to a planar size of 3 mm x 3 mm. The positive electrode tab was then attached to the exposed current collector by ultrasonic welding. Otherwise, the battery was manufactured in the same manner as in Example 1, and a bending test was performed.

[0082] Table 2 shows the battery configurations and bending test results for Examples 1, 5, and 6 and Comparative Examples 6 to 8.

[0083] [Table 2]

[0084] In Table 2, "Current collector thickness" represents the thickness [μm] of the current collector of the positive electrode, "Electrode thickness" represents the thickness [μm] of the positive electrode including the current collector and the positive electrode composite material, and "Number of edges in contact with the positive electrode composite material" represents the number of edges [lines] in contact with the positive electrode composite material in the portion of the current collector that is exposed without the positive electrode composite material, as viewed from above.

[0085] In Table 2, "Initial Resistance" represents the resistance [Ω] measured before the bending test, and "Resistance After Bending Test" represents the resistance [Ω] measured after the bending test. Table 2 shows that when the number of edges in contact with the positive electrode material in the exposed portion of the current collector where no positive electrode material is provided is only one (Comparative Examples 6-8), the resistance increase from the initial resistance after the bending test is relatively large. In contrast, when the number of edges in contact with the positive electrode material in the exposed portion of the current collector where no positive electrode material is provided is two or more (Examples 1, 5, 6), the resistance increase from the initial resistance after the bending test is kept relatively small. [Explanation of symbols]

[0086] 1 battery 2 Positive electrode 3. Negative electrode 4 Separators 5 Positive Tab 6 Negative Electrode Tabs 7 Tab film 8. Exterior 8a Outer film 10,100,100A,100B,100C electrode 11,101 Current collector 11a,11b,101a,101b Main surface 11c through hole 11d part 11da, 11db, 11dc, 11dd, 11de sides 12,102 Electrode composite material 13 Electrode Tabs 13a Connection part

Claims

1. An exterior body formed using a laminate film in which insulating layers are laminated on both main surfaces of a metal layer, The first electrode housed in the outer casing and Includes, The first electrode is A current collector having opposing first main surface and second main surface, and a through hole penetrating between the first main surface and the second main surface, The electrode composite material provided on the first main surface, the second main surface, and the through hole of the current collector, or within the through hole of the current collector Equipped with, When the thickness of the current collector in the first direction where the first main surface and the second main surface of the current collector face each other is d1, and the thickness of the first electrode in the first direction is d2, then d1 ≤ d2, d2 ≥ 150 μm, and the relationship d1 / d2 ≥ 0.2 is satisfied. The current collector has a first portion that is polygonal in plan view and is exposed from the electrode composite material, The first portion is in contact with the electrode composite material on two or more sides in a plan view, A battery characterized in that a first terminal is connected to the first part.

2. The battery according to claim 1, characterized in that the current collector is made of a metal foil or metal plate having a porous mesh structure.

3. Opposing positive electrode and negative electrode, An intervening layer containing an electrolyte is interposed between the positive electrode and the negative electrode, Includes, The positive electrode, the negative electrode, and the intervening layer are housed in the outer casing. The battery according to claim 1 or 2, characterized in that the first electrode is the positive electrode or the negative electrode.

4. Opposing positive electrode and negative electrode, An intervening layer containing an electrolyte is interposed between the positive electrode and the negative electrode, Includes, The positive electrode, the negative electrode, and the intervening layer are housed in the outer casing. The positive electrode includes the first electrode, The battery according to claim 1 or 2, characterized in that the negative electrode includes a metal layer.

5. The electrode composite material of the first electrode contains manganese dioxide, The battery according to claim 4, characterized in that the metal layer includes metallic lithium or a lithium aluminum alloy.

6. The battery according to any one of claims 1 to 5, characterized in that the current collector has a plurality of through holes.

7. A current collector having opposing first main surface and second main surface, and a through hole penetrating between the first main surface and the second main surface, The electrode composite material provided on the first main surface, the second main surface, and the through hole of the current collector, or within the through hole of the current collector A step of forming a first electrode comprising, The first electrode is housed in an outer casing formed using a laminate film in which insulating layers are laminated on both main surfaces of a metal layer. Includes, The first electrode is When the thickness of the current collector in the first direction where the first main surface and the second main surface of the current collector face each other is d1, and the thickness of the first electrode in the first direction is d2, then d1 ≤ d2, d2 ≥ 150 μm, and the relationship d1 / d2 ≥ 0.2 is satisfied. The current collector has a first portion that is polygonal in plan view and is exposed from the electrode composite material, The first portion is in contact with the electrode composite material on two or more sides in a plan view, A method for manufacturing a battery, characterized in that a first terminal is connected to the first part.

Images