Battery

Abstract

To provide a battery that can effectively prevent foreign matter from entering an electrode body without reducing the capacity.SOLUTION: A battery according to the present invention includes an electrode body in which positive and negative electrode plates are stacked with a separator between them, an exterior body having an opening and housing the electrode body, a sealing plate that seals the opening, and an external terminal attached to the sealing plate. A tab portion provided on at least one of the positive and negative electrode plates is electrically connected to the external terminal via a current collector arranged between the electrode body and the sealing plate. The tab portion and the current collector are welded, and the portion where the tab portion and the current collector are welded is covered with a covering member.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a battery. [Background technology]

[0002] 2. Description of the Related Art Batteries such as alkaline secondary batteries and non-aqueous electrolyte secondary batteries are used in stationary storage battery systems, etc., for purposes such as power sources for driving electric vehicles (EVs) and hybrid electric vehicles (HEVs, PHEVs), for suppressing output fluctuations in solar power generation, wind power generation, etc., and for peak shifting of grid power by storing electricity at night for use during the day.

[0003] The above-mentioned battery may be contaminated with foreign matter during assembly, etc., and if the contaminated foreign matter is a metal foreign matter, it may cause an internal short circuit. The mechanism of the internal short circuit is as follows.

[0004] First, when a metallic foreign object adheres to the positive electrode material, it dissolves as a metal ion in the electrolyte due to the high potential of the positive electrode, and when the metal ion reaches the negative electrode, it precipitates as a metal. The metal then precipitates as it grows toward the positive electrode, and if the metal breaks through the separator and comes into contact with the positive electrode, an internal short circuit occurs.

[0005] In order to prevent foreign matter such as metallic foreign matter from being mixed into the battery, secondary batteries are usually assembled in a clean room. Metallic foreign matter that adheres to the electrode body during assembly is removed by air blowing, suction, magnetic attraction, wiping with abrasive tape, etc.

[0006] Patent Document 1 proposes a sealed battery formed by inserting an electrode body into a bag-shaped porous body, and then inserting the porous body with the electrode body inserted into a sealed container. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2009-87812 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, the method described in Patent Document 1 does not specifically explain the method or advantages of disposing a porous body between the electrode body and the lid of the sealed container, and the specific method is unclear. In addition, since a bag-shaped porous body is used, the amount of active material is reduced accordingly, resulting in a reduced battery capacity.

[0009] The present invention has been made in consideration of these points, and its object is to provide a battery that can effectively suppress the intrusion of foreign matter into the electrode body without reducing the battery capacity. [Means for solving the problem]

[0010] The battery of the present invention comprises an electrode body in which positive and negative electrode plates are stacked with a separator between them, an exterior body having an opening and housing the electrode body, a sealing plate that seals the opening, and an external terminal attached to the sealing plate, wherein a tab portion provided on at least one of the positive and negative electrode plates is electrically connected to the external terminal via a current collector arranged between the electrode body and the sealing plate, the tab portion and the current collector are welded, and the portion where the tab portion and the current collector are welded is covered with a covering member, the sealing plate is provided with a liquid injection hole for injecting an electrolyte into the exterior body, and the opening of the liquid injection hole on the electrode body side faces the covering member while being spaced apart from the covering member.

[0011] Furthermore, the battery of the present invention may comprise an electrode body in which positive and negative electrode plates are stacked with a separator interposed therebetween, an exterior body having an opening and housing the electrode body, a sealing plate that seals the opening, and an external terminal attached to the sealing plate, wherein a tab portion provided on at least one of the positive and negative electrode plates is electrically connected to the external terminal via a current collector arranged between the electrode body and the sealing plate, the tab portion and the current collector are welded, and the portion where the tab portion and the current collector are welded is covered with a covering member.

[0012] The electrode body includes a first electrode body element including the positive electrode plate and the negative electrode plate, and a second electrode body element including the positive electrode plate and the negative electrode plate, the first electrode body element has a first tab group consisting of a plurality of the tab portions, the second electrode body element has a second tab group consisting of a plurality of the tab portions, the first tab group and the second tab group are each welded to the current collector, a first welded portion at which the first tab group and the current collector are welded and a second welded portion at which the second tab group and the current collector are welded are each covered by the covering member, and the covering member may also be disposed over an area between the first welded portion and the second welded portion.

[0013] The current collector may have a first current collector and a second current collector, the tab portion may be welded to the first current collector, and a portion of the second current collector may be covered by the covering member.

[0014] The current collector may be provided with a liquid injection hole for injecting an electrolyte into the exterior body, and an opening of the liquid injection hole on the electrode body side may be covered and spaced apart by the covering member. The opening on the electrode body side being covered and spaced apart by the covering member means that the opening is covered by the covering member and is spaced apart from the current collector covering member.

[0015] An insulating tubular member protruding towards the electrode body may be disposed in the liquid inlet.

[0016] It is preferable that a gap through which the electrolyte passes is formed between the current collector and the periphery of the covering member covering the opening on the electrode body side of the electrolyte injection hole. That is, the gap between the current collector and the periphery of the covering member covering the opening on the electrode body side of the electrolyte injection hole is open, allowing the electrolyte to pass through.

[0017] The covering member covering the opening on the electrode body side of the liquid injection hole may have a hole through which the electrolyte passes formed in a portion other than the portion directly above the opening.

[0018] The battery of the present invention may include an electrode assembly in which positive and negative electrode plates are stacked with a separator interposed therebetween, an exterior body having an opening and housing the electrode assembly, a sealing plate that seals the opening, and a positive electrode external terminal and a negative electrode external terminal attached to the sealing plate, wherein a positive electrode tab provided on the positive electrode plate is electrically connected to the positive electrode external terminal via a positive electrode current collector arranged between the electrode assembly and the sealing plate, a negative electrode tab provided on the negative electrode plate is electrically connected to the negative electrode external terminal via a negative electrode current collector arranged between the electrode assembly and the sealing plate, the positive electrode tab and the positive electrode current collector are welded, the negative electrode tab and the negative electrode current collector are welded, a portion where the positive electrode tab and the positive electrode current collector are welded is covered with a first covering member, and a portion where the negative electrode tab and the negative electrode current collector are welded is covered with a second covering member.

[0019] The electrode body includes a first electrode body element including the positive electrode plate and the negative electrode plate, and a second electrode body element including the positive electrode plate and the negative electrode plate, the first electrode body element has a first positive electrode tab group consisting of a plurality of the positive electrode tabs, and a first negative electrode tab group consisting of a plurality of the negative electrode tabs, the second electrode body element has a second positive electrode tab group consisting of a plurality of the positive electrode tabs, and a second negative electrode tab group consisting of a plurality of the negative electrode tabs, the first positive electrode tab group and the second positive electrode tab group are each welded to the positive electrode current collector, the first negative electrode tab group and the second negative electrode tab group are each welded to the negative electrode current collector, and the first positive electrode tab a first welded portion where the first negative electrode tab group and the negative electrode current collector are welded and a second welded portion where the second positive electrode tab group and the positive electrode current collector are welded are each covered by the first covering member, and the first covering member is also disposed on the area between the first welded portion and the second welded portion; a third welded portion where the first negative electrode tab group and the negative electrode current collector are welded and a fourth welded portion where the second negative electrode tab group and the negative electrode current collector are welded are each covered by the second covering member, and the second covering member is also disposed on the area between the third welded portion and the fourth welded portion.

[0020] The positive electrode current collector may have a first positive electrode current collector and a second positive electrode current collector, the first positive electrode tab group and the second positive electrode tab group are welded to the first positive electrode current collector, and a portion of the second positive electrode current collector is covered by a first current collector covering member, and the negative electrode current collector may have a first negative electrode current collector and a second negative electrode current collector, the first negative electrode tab group and the second negative electrode tab group are welded to the first negative electrode current collector, and a portion of the second negative electrode current collector is covered by the second covering member.

[0021] At least one of the positive electrode current collector and the negative electrode current collector may be provided with an injection hole for injecting an electrolyte into the outer casing, and the opening of the injection hole on the electrode body side may be covered at a distance by at least one of the first covering member and the second covering member.

[0022] An insulating tubular member protruding towards the electrode body may be disposed in the liquid inlet.

[0023] It is preferable that a gap through which the electrolyte passes is formed between the peripheral edge of at least one of the first covering member and the second covering member covering the opening on the electrode body side of the liquid injection hole and at least one of the positive electrode current collector and the negative electrode current collector.

[0024] It is preferable that at least one of the first covering member and the second covering member which cover the opening on the electrode body side of the liquid injection hole has a hole through which the electrolyte passes in a portion other than the portion directly above the opening. Effect of the Invention

[0025] In the battery of the present invention, the portion where the tab portion and the current collector are welded is covered with a covering member, which more effectively prevents dust generated during welding from entering the inside of the electrode assembly. [Brief description of the drawings]

[0026] [Figure 1] 1 is a perspective view of a secondary battery according to an embodiment; [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 2 is a plan view of a first positive electrode current collector (positive electrode current collector). [Figure 7] FIG. 2 is a plan view of a first negative electrode current collector (negative electrode current collector). [Figure 8] FIG. 2 is a diagram showing a state in which a positive electrode tab group is connected to a first positive electrode current collector, and a negative electrode tab group is connected to a first negative electrode current collector. [Figure 9] 13 is a view showing the surface of the sealing plate on the electrode body side after a second positive electrode current collector and a second negative electrode current collector have been attached. FIG. [Figure 10]FIG. 13 is a diagram showing the surface of the sealing plate facing the electrode body after the first positive electrode current collector is attached to the second positive electrode current collector and the first negative electrode current collector is attached to the second negative electrode current collector. [Figure 11] FIG. 11 is a diagram showing a state in which a covering member is attached to the state shown in FIG. 10. [Figure 12] 12 is a diagram showing a state in which a cover member is attached to the state shown in FIG. 11. FIG. [Figure 13] FIG. 4 is a schematic enlarged perspective view of a portion where a first covering member is provided. [Figure 14] 14 is a schematic diagram showing a state in which a first covering member is removed from FIG. 13. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its application or its uses. In the following drawings, for the sake of simplicity, components having substantially the same functions are designated by the same reference numerals.

[0028] (Embodiment 1) The following describes the configuration of a rectangular secondary battery 20 as a secondary battery according to embodiment 1. Note that the present invention is not limited to the following embodiment.

[0029] As shown in Fig. 1 and Fig. 2, a prismatic secondary battery 20 includes a battery case 100 including a prismatic exterior body 1 in the form of a bottomed rectangular cylinder having an opening, and a sealing plate 2 that seals the opening of the prismatic exterior body 1. The prismatic exterior body 1 and the sealing plate 2 are each preferably made of metal, and preferably made of aluminum or an aluminum alloy. The prismatic exterior body 1 houses an electrode body 3, in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween, together with an electrolyte. As will be described later, in this embodiment, the electrode body 3 is made of a first electrode body element and a second electrode body element, and these two electrode body elements have the same structure.

[0030] As shown in FIG. 5, a positive electrode tab group 40A consisting of a plurality of positive electrode tabs (tab portion) 40 and a negative electrode tab group 50A consisting of a plurality of negative electrode tabs (tab portion) 50 are provided at the end of the electrode body 3 on the sealing plate 2 side. The positive electrode tab group 40A is electrically connected to the positive electrode terminal 7 via a first positive electrode current collector (positive electrode current collector) 6a and a second positive electrode current collector 6b. The negative electrode tab group 50A is electrically connected to the negative electrode terminal 9 via a first negative electrode current collector (negative electrode current collector) 8a and a second negative electrode current collector 8b. The first and second positive electrode current collectors 6a, 6b and the first and second negative electrode current collectors 8a, 8b are attached to the sealing plate 2 on the inner side of the battery, and the connection with the positive electrode tab group 40A and the negative electrode tab group 50A is also made on the surface on the inner side of the battery.

[0031] The second positive electrode current collector 6b, the first positive electrode current collector 6a, and the positive electrode terminal 7 are preferably made of a metal, and more preferably made of aluminum or an aluminum alloy. A resin outer insulating member 10 is disposed between the positive electrode terminal 7 and the sealing plate 2. A resin inner insulating member 11 is disposed between the second positive electrode current collector 6b and the first positive electrode current collector 6a, and the sealing plate 2.

[0032] The second negative electrode current collector 8b, the first negative electrode current collector 8a, and the negative electrode terminal 9 are preferably made of metal, more preferably made of copper or a copper alloy. The negative electrode terminal 9 preferably has a portion made of aluminum or an aluminum alloy and a portion made of copper or a copper alloy. In this case, it is preferable that the portion made of copper or a copper alloy is connected to the second negative electrode current collector 8b, and the portion made of aluminum or an aluminum alloy protrudes to the outside beyond the sealing plate 2. An external insulating member 12 made of resin is disposed between the negative electrode terminal 9 and the sealing plate 2. An internal insulating member 13 made of resin is disposed between the second negative electrode current collector 8b and the first negative electrode current collector 8a, and the sealing plate 2.

[0033] An electrode assembly holder 14 made of a resin sheet is disposed between the electrode assembly 3 and the rectangular exterior body 1. The electrode assembly holder 14 is preferably formed by folding an insulating resin sheet into a bag or box shape. This electrode assembly holder 14 reliably maintains an electrically insulated state between the electrode assembly 3 and the rectangular exterior body 1.

[0034] The sealing plate 2 is provided with an electrolyte injection hole 15, which is sealed with a sealing member (not shown) after the electrolyte is injected. The sealing plate 2 is provided with a gas exhaust valve 17 that breaks when the pressure inside the battery case 100 reaches or exceeds a predetermined value to exhaust gas inside the battery case 100 to the outside of the battery case 100.

[0035] Next, a method for manufacturing the prismatic secondary battery 20 and each of its components will be described in detail.

[0036] [Positive plate] First, a method for manufacturing the positive electrode plate will be described.

[0037] [Preparation of positive electrode active material mixture layer slurry] The positive electrode active material mixture layer slurry is prepared by kneading, for example, a positive electrode active material, a conductive agent, and a binder. The positive electrode active material may be, for example, a lithium composite oxide such as a lithium nickel cobalt manganese composite oxide. The binder may be, for example, a fluororesin such as polyvinylidene fluoride (PVdF). The conductive agent may be, for example, a carbon material such as carbon black.

[0038] [Preparation of positive electrode protective layer slurry] Alumina powder, graphite as a conductive agent, polyvinylidene fluoride (PVdF) as a binder, N-methyl-2-pyrrolidone (NMP) as a dispersion medium, and the like are mixed together to prepare a positive electrode protective layer slurry.

[0039] [Formation of positive electrode active material mixture layer and positive electrode protective layer] The positive electrode active material mixture layer slurry and the positive electrode protective layer slurry prepared by the above-mentioned method are applied to both sides of an aluminum foil having a thickness of 15 μm as a positive electrode core by a die coater, and the positive electrode protective layer slurry is applied to at least one end in the width direction of the region where the positive electrode active material mixture layer slurry is applied.

[0040] The positive electrode core coated with the positive electrode active material mixture layer slurry and the positive electrode protective layer slurry is dried to remove NMP from the slurry. This forms the positive electrode active material mixture layer and protective layer. Then, the positive electrode active material mixture layer is compressed by passing it between a pair of press rollers to form a positive electrode original plate. This positive electrode original plate is cut to a predetermined size to form the positive electrode plate 4 shown in FIG. 3. The positive electrode plate 4 is rectangular, and a positive electrode tab 40 protrudes from the upper side of the rectangle. A narrow positive electrode protective layer 4c is formed along the upper side portion of the positive electrode plate 4, and a positive electrode active material mixture layer 4b is formed from under the positive electrode protective layer 4c to the lower side of the positive electrode plate 4. As described above, the positive electrode tab 40 may be formed from the positive electrode core, or a separate member may be connected to the positive electrode plate to form a positive electrode tab.

[0041] [Negative plate] Next, a method for manufacturing the negative electrode plate will be described.

[0042] [Preparation of negative electrode active material mixture layer slurry] The negative electrode active material mixture layer slurry is prepared by kneading, for example, a negative electrode active material, a conductive agent, a binder, and a thickener. Examples of the negative electrode active material include carbon materials such as graphite. Examples of the binder include styrene butadiene rubber (SBR). Examples of the thickener include carboxymethyl cellulose (CMC).

[0043] [Formation of negative electrode active material mixture layer] The negative electrode active material mixture layer slurry prepared by the above-mentioned method is applied by a die coater to both sides of a copper foil having a thickness of 8 μm as a negative electrode core.

[0044] The negative electrode core coated with the negative electrode active material mixture layer slurry is dried to remove water from the slurry. This forms a negative electrode active material mixture layer. The negative electrode active material mixture layer is then compressed by passing it between a pair of press rollers to form a negative electrode original plate. This negative electrode original plate is cut to a predetermined size to form a negative electrode plate 5 shown in FIG. 4. The negative electrode plate 4 is rectangular, and a negative electrode tab 50 protrudes from the upper side of the rectangle. A negative electrode active material mixture layer 5b is formed on the entire surface of the negative electrode core except for the negative electrode tab 50. As described above, the negative electrode tab 50 may be formed from the negative electrode core, or a separate member may be connected to the negative electrode plate to form the negative electrode tab.

[0045] [Preparation of electrode body] A plurality of positive electrode plates 4 and negative electrode plates 5 produced by the above-mentioned method are stacked with separators interposed therebetween to produce a stacked electrode body 3. The number of positive electrode plates 4 and negative electrode plates 5 included in the electrode body 3 is not particularly limited, but several tens of sheets or more are preferable. As shown in Fig. 5, a positive electrode tab group 40A consisting of a plurality of positive electrode tabs 40 and a negative electrode tab group 50A consisting of a plurality of negative electrode tabs 50 are provided at one end of the electrode body 3.

[0046] [Connection between current collector and tab] The above-mentioned positive electrode tab group 40A is connected to the first positive electrode current collector 6a shown in Fig. 6 by welding. A current collector through hole 6e is formed in the first positive electrode current collector 6a at a position facing the electrolyte injection hole 15 of the sealing plate 2. The above-mentioned negative electrode tab group 50A is connected to the first negative electrode current collector 8a shown in Fig. 7 by welding. Fig. 8 shows a state in which the positive electrode tab group 40A and the first positive electrode current collector 6a are connected, and the negative electrode tab group 50A and the first negative electrode current collector 8a are connected.

[0047] In this embodiment, the electrode body 3 is composed of a first electrode body element 3a and a second electrode body element 3b, as shown in Fig. 8. The first electrode body element 3a and the second electrode body element 3b are fabricated by the same method as the fabrication method of the electrode body 3 described above.

[0048] The first positive electrode tab group 40A1 of the first electrode body element 3a and the second positive electrode tab group 40A2 of the second electrode body element 3b are connected to the first positive electrode current collector (positive electrode current collector) 6a, and the first negative electrode tab group 50A1 of the first electrode body element 3a and the second negative electrode tab group 50A2 of the second electrode body element 3b are connected to the first negative electrode current collector (negative electrode current collector) 8a. The first and second positive electrode tab groups 40A1, 40A2 are welded to the first positive electrode current collector 6a to form welded connections 60a, 60b. The two welded connections 60a, 60b on the positive electrode side are formed apart from each other in a direction perpendicular to the upper side of the electrode body 3, i.e., in a direction perpendicular to the longitudinal direction of the sealing body 2. The collector through hole 6e is located between the two welded connections 60a, 60b of the positive electrode.

[0049] The negative electrode tab groups 50A1, 50A2 are welded to the first negative electrode current collector 8a to form welded connections 61a, 61b. The two welded connections 61a, 61b on the negative electrode side are also formed spaced apart from each other in a direction perpendicular to the upper side of the electrode body 3, i.e., in a direction perpendicular to the longitudinal direction of the sealing body 2.

[0050] The first positive electrode current collector 6a has a thin portion 6c formed thereon, where the first positive electrode current collector 6a is connected to the second positive electrode current collector 6b.

[0051] A recess 8d is formed in the first negative electrode current collector 8a, and a thin portion 8c is formed in the recess 8d. At this thin portion 8c, the first negative electrode current collector 8a is connected to the second negative electrode current collector 8b.

[0052] The welded connection between the positive electrode tab group 40A and the first positive electrode current collector 6a and the welded connection between the negative electrode tab group 50A and the first negative electrode current collector 8a can be performed by ultrasonic welding, resistance welding, laser welding, etc. In this embodiment, the welded connections are performed by ultrasonic welding.

[0053] The first positive electrode current collector 6a and the second positive electrode current collector 6b, and the first negative electrode current collector 8a and the second negative electrode current collector 8b can be connected by ultrasonic welding, resistance welding, laser welding, etc. In this embodiment, the connections are made by laser welding.

[0054] [Installing each part on the sealing plate] 9 is a diagram showing the surface of the sealing plate 2 on the inner side of the battery, to which each component is attached. The attachment of each component to the sealing plate 2 will be described with reference to FIGS.

[0055] The external insulating member 10 is disposed around the positive terminal insertion hole of the sealing plate 2. The internal insulating member 11 and the cup-shaped conductive member 65 are disposed on the inner surface side of the battery around the positive terminal insertion hole of the sealing plate 2. Then, the positive terminal 7 is inserted from the outside of the battery into the through hole of the external insulating member 10, the positive terminal insertion hole of the sealing plate 2, the through hole of the internal insulating member 11, and the terminal connection hole of the conductive member 65, and the tip of the positive terminal 7 is crimped onto the conductive member 65. As a result, the positive terminal 7 and the conductive member 65 are fixed to the sealing plate 2. It is preferable to connect the crimped portion of the positive terminal 7 and the conductive member 65 by welding.

[0056] The conductive member 65 has an opening on the inner side of the battery. A disk-shaped deformable plate 66 is placed over the opening of the conductive member 65 so as to close the opening, and the periphery of the deformable plate 66 is welded and connected to the conductive member 65. This seals the opening. The conductive member 65 and the deformable plate 66 are preferably made of metal, and more preferably made of aluminum or an aluminum alloy. Then, the second positive electrode collector 6b is placed on the inner side of the battery of the deformable plate 66, and the two are welded and connected.

[0057] Next, the external insulating member 12 is arranged on the outer surface side of the battery around the negative terminal insertion hole of the sealing plate 2. The internal insulating member 13 and the second negative electrode current collector 8b are arranged on the inner surface side of the battery around the negative terminal insertion hole of the sealing plate 2. Then, the negative electrode terminal 9 is inserted from the outside of the battery into the through hole of the external insulating member 12, the negative electrode terminal insertion hole of the sealing plate 2, the through hole of the internal insulating member 13, and the terminal connection hole of the second negative electrode current collector 8b, and the tip of the negative electrode terminal 9 is crimped onto the second negative electrode current collector 8b. As a result, the negative electrode terminal 9 and the second negative electrode current collector 8b are fixed to the sealing plate 2. It is preferable to connect the crimped portion of the negative electrode terminal 9 to the second negative electrode current collector 8b by welding.

[0058] In the positive electrode side inner insulating member 11, a liquid injection opening 11a is provided at a portion facing the electrolyte injection hole 15 provided in the sealing plate 2. A cylindrical portion 11b that protrudes in a cylindrical shape toward the inside of the battery is provided at the edge of the liquid injection opening 11a. Furthermore, an opening cover portion 11c is provided that protrudes from two points on the edge of the cylindrical portion 11b toward the inside of the battery and connects the two points in a bridge shape. The cylindrical portion 11b and the opening cover portion 11c are inserted into a collector through hole 6e provided in the first positive electrode collector 6a.

[0059] [Connection between the first and second collectors] FIG. 10 is a diagram showing the surface of the sealing plate 2 facing the inside of the battery after the first positive electrode current collector 6a has been attached to the second positive electrode current collector 6b and the first negative electrode current collector 8a has been attached to the second negative electrode current collector 8b.

[0060] The first positive electrode current collector 6a to which the first and second positive electrode tab groups 40A1 and 40A2 are connected is placed on the inner insulating member 11 so that a part of the first positive electrode current collector 6a overlaps with the second positive electrode current collector 6b. Then, the thin-walled portion 6c is irradiated with a laser to weld the first positive electrode current collector 6a and the second positive electrode current collector 6b together, forming a positive electrode current collector welded connection portion. Also, the first negative electrode current collector 8a to which the first and second negative electrode tab groups 50A1 and 50A2 are connected is placed on the inner insulating member 13 so that a part of the first negative electrode current collector 8a overlaps with the second negative electrode current collector 8b together. Then, the thin-walled portion 8c is irradiated with a laser to weld the first negative electrode current collector 8a and the second negative electrode current collector 8b together, forming a negative electrode current collector welded connection portion.

[0061] [Coating of connection parts] As shown in FIG. 11, the welded connection 60a between the first positive electrode current collector 6a and the first positive electrode tab group 40A1 and the welded connection 60b between the first positive electrode current collector 6a and the second positive electrode tab group 40A2 are covered with a first covering member 81. In this manner, the first covering member 81 captures foreign matter present at the welded connections 60a, 60b, particularly metal powder generated during the welding process, and prevents the foreign matter from entering the inside of the electrode body 3. Therefore, the occurrence of an internal short circuit due to foreign matter can be significantly suppressed. The first covering member 81 is attached to the welded connections 60a, 60b, and in the region between the two welded connections 60a, 60b, the first covering member 81 is separated from the region and covers the region.

[0062] Next, the welded connection 61a between the first negative electrode current collector 8a and the first negative electrode tab group 50A1 and the welded connection 61b between the first negative electrode current collector 8a and the second negative electrode tab group 50A2 are covered with the second covering member 82. The second covering member 82 also covers the surface of the first negative electrode current collector 8a sandwiched between the two welded connections 61a, 61b. In this manner, the second covering member 82 can capture foreign matter present at the welded connections 61a, 61b, particularly metal powder generated during the welding process, to prevent the foreign matter from entering the inside of the electrode body 3. Therefore, the occurrence of an internal short circuit due to foreign matter can be significantly suppressed. The second covering member 82 is attached to the covered portion.

[0063] Furthermore, the second covering member 82 also covers the connection portion (negative current collector welded connection portion) between the first negative current collector 8a and the second negative current collector 8b. That is, a portion of the second negative current collector 8b is covered by the second covering member 82. For this reason, the second covering member 82 captures foreign matter (metal powder) generated by welding the first negative current collector 8a and the second negative current collector 8b, and can prevent this foreign matter from entering the inside of the electrode body 3.

[0064] Then, a third covering member 83 is arranged and bonded to cover the connection portion (positive collector welded connection portion) between the first positive current collector 6a and the second positive current collector 6b. In this manner, the third covering member 83 can capture foreign matter present at the positive collector welded connection portion, particularly metal powder generated during the welding process between the first positive current collector 6a and the second positive current collector 6b, so as to prevent the foreign matter from entering the inside of the electrode body 3. Then, the second positive current collector 6b and the third covering member 83 are covered with a cover member 88 as shown in FIG.

[0065] In this embodiment, the first to third covering members 81, 82, and 83 are adhesive sheets formed by applying an adhesive to a plastic film. The plastic film is not particularly limited, but a polypropylene film is preferable. The first to third covering members 81, 82, and 83 are not limited to adhesive sheets.

[0066] [Preparation of secondary battery] Next, the two positive electrode tab groups 40A1, 40A2 and the two negative electrode tab groups 50A1, 50A2 are curved so that the upper surface of the first electrode body element 3a and the upper surface of the second electrode body element 3b in Fig. 12 are in contact directly or via another member. This combines the two electrode body elements 3a, 3b into one electrode body 3. The combined electrode body 3 is then placed in an electrode body holder 14 made of an insulating sheet formed into a box or bag shape.

[0067] The electrode body 3 wrapped in the electrode body holder 14 is inserted into the rectangular exterior body 1. Then, the sealing plate 2 and the rectangular exterior body 1 are welded together, and the opening of the rectangular exterior body 1 is sealed with the sealing plate 2. Then, electrolyte is injected into the rectangular exterior body 1 through an electrolyte injection hole 15 provided in the sealing plate 2. After that, the electrolyte injection hole 15 is sealed with a sealing member such as a blind rivet. This completes the rectangular secondary battery 20.

[0068] [Aspects of the first covering member and the liquid injection portion] FIG. 13 is an enlarged perspective view of a portion where the first covering member 81 is provided. The first covering member 81 includes bonding portions 81a, 81b bonded to the welded joints 60a, 60b, and a separation portion 81c separated and raised from the first positive current collector 6a. As shown in FIG. 14, which shows a state in which only the first covering member 81 is removed from FIG. 13, the separation portion 81c is separated from the first positive current collector 6a so as not to block the opening of the collector through hole 6e provided in the first positive current collector 6a and the opening portion of the cylindrical portion 11b. A gap 87 is formed between the periphery 85 of the separation portion 81c in the first covering member 81 and the first positive current collector 6a.

[0069] As described above, after assembling the secondary battery 20, the electrolyte is poured from the electrolyte pouring hole 15. At this time, the electrolyte passes through the cylindrical portion 11b and collides with the opening cover portion 11c, then collides with the separation portion 81c of the first covering member 81, flows along the inner surface side of the separation portion 81c, and flows into the electrode body 3 through the gap 87. If it is assumed that there is no opening cover portion 11c or the first covering member 81 and the electrolyte flows directly from the cylindrical portion 11b into the electrode body 3, the electrolyte will collide with the electrode body 3 with the momentum and inflow speed as it is poured. In that case, the electrolyte will collide with the upper end portion of the separator protruding from the upper side of the electrode body 3, causing the separator to turn up, which may cause an internal short circuit. However, in the battery of this embodiment, the inflow speed of the electrolyte is reduced, so the separator will not turn up. In this embodiment, the inflow speed of the electrolyte is reduced by both the opening covering portion 11c and the first covering member 81, so that curling up of the separator can be effectively prevented.

[0070] (Other embodiments) The above-mentioned embodiments are merely examples of the present invention, and the present invention is not limited to these examples, and these examples may be combined with well-known, commonly used, or publicly known technologies, or may be partially replaced. In addition, modified inventions that can be easily conceived by a person skilled in the art are also included in the present invention.

[0071] The electrode body may have a structure in which a positive electrode plate, a negative electrode plate, and a separator are laminated and then wound. The electrode body element may also have a wound structure.

[0072] In the above-described embodiment, an example has been shown in which two electrode body elements are arranged inside the exterior body, but the number of electrode body elements may be one, or three or more.

[0073] In the above embodiment, an example has been shown in which the positive electrode current collector and the negative electrode current collector are each made up of two parts, but each of the positive electrode current collector and the negative electrode current collector may be made up of a single part.

[0074] Known materials can be used for the positive electrode plate, the negative electrode plate, the separator, the electrolyte, and the like.

[0075] The covering member may be any material capable of capturing foreign matter, and is not limited to an adhesive sheet using a plastic film. For example, a coating material such as a sealing resin that hardens with heat or light may be used as the covering member, or an adhesive sheet using a metal foil or nonwoven fabric may be used.

[0076] The first covering member does not need to have a gap around the periphery of the separation portion. In that case, it is sufficient to provide a hole through which the electrolyte flows out in the first covering member. This hole is provided at a position horizontally away from the opening of the cylindrical portion. In other words, the hole is provided in a position other than directly above the opening of the cylindrical portion. This allows the electrolyte to first collide with the first covering member, slowing down the flow rate, and then flow through the hole toward the electrode body. [Explanation of symbols]

[0077] 1. Rectangular exterior body (exterior body) 2...Sealing plate 3...electrode body 3a...First electrode body element 3b...Second electrode body element 4. Positive electrode plate 5 Negative electrode plate 6a...First positive electrode current collector 6b...Second positive electrode current collector 6e...Collector through hole (liquid injection hole) 7 Positive terminal (positive external terminal) 8a...First negative electrode current collector 8b...Second negative electrode current collector 9 Negative terminal (negative external terminal) 11b Cylindrical part 11c Opening cover 15...Electrolyte injection hole 20 Prismatic secondary battery (battery) 40 Positive electrode tab (tab part) 40A···Positive electrode tab group 40A1: First positive electrode tab group 40A2: Second positive electrode tab group 50 Negative electrode tab (tab part) 50A Negative electrode tab group 50A1: First negative electrode tab group 50A2: Second negative electrode tab group 60a, 60b... Welded connection portion (first welded portion) 61a, 61b: Welded connection (second welded portion) 81... First covering member 82...Second covering member

Claims

[Claim 1] an electrode assembly in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween; An exterior body having an opening and housing the electrode assembly; a sealing plate that seals the opening; An external terminal attached to the sealing plate; Equipped with a tab portion provided on at least one of the positive electrode plate and the negative electrode plate is electrically connected to the external terminal via a current collector disposed between the electrode body and the sealing plate, The tab portion and the current collector are welded together, a portion where the tab portion and the current collector are welded is covered with a covering member, The battery, wherein the sealing plate is provided with an injection hole for injecting an electrolyte into the exterior body, and an opening of the injection hole on the electrode body side faces the covering member while being spaced apart from the covering member.

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