Battery

Abstract

To provide a battery capable of effectively reducing foreign objects mixed into an electrode body, without reducing the battery capacity.SOLUTION: A battery includes: an electrode body 3 obtained by stacking a positive electrode plate and a negative electrode plate with a separator interposed therebetween, the positive electrode plate including a first positive electrode tab group 40A; an exterior body having an opening and housing the electrode body 3; a sealing plate 2 sealing the opening; a positive electrode terminal 7 attached to the sealing plate 2; and a substantially plate-shaped positive electrode current collector 6 arranged substantially parallel to the sealing plate 2 between the electrode body 3 and the sealing plate 2 and electrically connected to the positive electrode terminal 7. A positive electrode tab group 40A of the electrode body 3 is welded to a surface of the positive electrode current collector 6 facing the electrode body 3, and a second tape 82 covers an area corresponding to the back of a welding area of the positive electrode tab group 40A on the surface of the positive electrode current collector 6 facing the sealing plate 2.SELECTED DRAWING: Figure 13

Description

[Technical Field]

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

[0002] Batteries such as alkaline secondary batteries and non-aqueous electrolyte secondary batteries are used in stationary storage battery systems, 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] Foreign matter may be mixed into the battery during assembly, etc., and if the mixed foreign matter is metallic, an internal short circuit may occur. The mechanism of the internal short circuit is as follows.

[0004] First, when metallic foreign matter adheres to the positive electrode material, it dissolves as metal ions in the electrolyte due to the high potential of the positive electrode, and when these metal ions reach the negative electrode, they deposit as metal. The metal then deposits, growing 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] To prevent foreign matter such as metallic particles from getting into the battery, secondary batteries are usually assembled in a clean room. Any metallic particles that adhere to the electrode body during assembly are 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] Japanese Patent Application Laid-Open No. 2009-87812 Summary of the Invention

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

[0009] The present invention has been made in consideration of these points, and its purpose is to provide a battery that can effectively prevent foreign matter from entering the electrode body without reducing the battery capacity.

[0010] The battery of the present invention comprises an electrode body in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween, and a tab portion is provided on at least one of the positive electrode plate and the negative electrode plate; an exterior body having an opening and housing the electrode body; a sealing plate that seals the opening; an external terminal attached to the sealing plate; and a substantially plate-shaped current collector that is disposed between the electrode body and the sealing plate substantially parallel to the sealing plate and is electrically connected to the external terminal, wherein the tab portion of the electrode body is welded to the surface of the current collector facing the electrode body, and a sealing plate side covering member is affixed to an area on the surface of the current collector facing the sealing plate that corresponds to the back side of the welding area of ​​the tab portion.

[0011] An internal insulating member is fixed to the sealing plate, and a flat region is formed on the surface of the internal insulating member facing the electrode body. The current collector includes a substantially plate-shaped first current collector having a first region and a second region located closer to the electrode body than the first region on its surface facing the sealing plate, and a substantially plate-shaped second current collector welded to the second region of the first current collector, and the thickness of the second current collector is set to be larger than the sum of the height difference between the first and second regions of the first current collector and the thickness of the sealing plate-side covering member, and the first region of the first current collector is covered by the sealing plate-side covering member, and the sealing plate-side surface of the second current collector abuts the flat region of the internal insulating member, while the electrode body-side surface of the second current collector abuts the second region of the first current collector.

[0012] The portion of the tab portion that is welded to the current collector may be covered with an electrode body side covering member.

[0013] The battery of the present invention includes an electrode assembly in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween, and a positive electrode tab is provided on the positive electrode plate and a negative electrode tab is provided on the negative electrode plate; an exterior body having an opening and housing the electrode assembly; a sealing plate that seals the opening; a positive electrode terminal and a negative electrode terminal attached to the sealing plate; a substantially plate-shaped positive electrode current collector that is disposed between the electrode assembly and the sealing plate substantially parallel to the sealing plate and is electrically connected to the positive electrode terminal; and a substantially plate-shaped negative electrode current collector electrically connected to a negative electrode terminal, wherein a positive electrode tab of the electrode body is welded to the electrode body side surface of the positive electrode current collector, a negative electrode tab of the electrode body is welded to the electrode body side surface of the negative electrode current collector, an area of ​​the sealing plate side surface of the positive electrode current collector corresponding to a rear side of the welded area of ​​the positive electrode tab is covered by a first sealing plate side covering member, and an area of ​​the sealing plate side surface of the negative electrode current collector corresponding to a rear side of the welded area of ​​the negative electrode tab is covered by a second sealing plate side covering member.

[0014] In the battery of the present invention, the area of ​​the current collector facing the sealing plate, which corresponds to the back side of the welding area of ​​the tab portion, is covered with a sealing plate side covering member, thereby preventing dust that is generated during welding and adheres to the sealing plate side of the current collector from penetrating into the interior of the electrode body. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view of a secondary battery according to an embodiment; [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 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. 10 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] FIG. 10 is a view showing the surface of the sealing plate facing the electrode body after the second positive electrode current collector and the second negative electrode current collector have been attached. [Figure 10] FIG. 10 is a view 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 the state in which the first, third, and fourth tapes are attached to the state shown in FIG. 10. [Figure 12] 12 is a diagram showing the state in which a cover member is attached to the state shown in FIG. 11. FIG. [Figure 13] FIG. 2 is a cross-sectional view taken along line XIII-XIII in FIG. [Figure 14] FIG. 2 is a cross-sectional view taken along line XIV-XIV in FIG. [Figure 15] FIG. 9 is a diagram showing the state of FIG. 8 with second and fifth tapes attached. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, 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.

[0017] (Embodiment) The configuration of a prismatic secondary battery 20 as a secondary battery according to this embodiment will be described below. Note that the present invention is not limited to the following embodiment.

[0018] As shown in FIGS. 1 and 2 , a prismatic secondary battery 20 includes a battery case 100 composed of a prismatic outer casing 1 in the shape of a rectangular cylinder with a bottom and an opening, and a sealing plate 2 in the shape of a substantially rectangular plate that seals the opening of the prismatic outer casing 1. The prismatic outer casing 1 and the sealing plate 2 are preferably made of metal, preferably aluminum or an aluminum alloy. A positive electrode terminal insertion hole 2a and a negative electrode terminal insertion hole 2b are formed near both longitudinal ends of the sealing plate 2. An electrolyte injection hole 15 is provided in the sealing plate 2 closer to the positive electrode terminal insertion hole 2a than the longitudinal center of the sealing plate 2, and the electrolyte injection hole 15 is sealed with a sealing member (not shown) after the electrolyte is injected. A gas release valve 17 is provided in the longitudinal center of the sealing plate 2. The gas release valve 17 breaks when the pressure inside the battery case 100 exceeds a predetermined value, thereby releasing gas inside the battery case 100 to the outside.

[0019] The rectangular exterior body 1 houses an electrode assembly 3, which is made up of a positive electrode plate 4 shown in Fig. 3 and a negative electrode plate 5 shown in Fig. 4 stacked with a separator interposed therebetween, together with an electrolyte. The positive electrode plate 4 has a positive electrode tab 40, and the negative electrode plate 5 has a negative electrode tab 50.

[0020] 5, a positive electrode tab group 40A consisting of multiple positive electrode tabs (tab portions) 40 protruding toward the sealing plate 2, and a negative electrode tab group 50A consisting of multiple negative electrode tabs (tab portions) 50 protruding toward the sealing plate 2, are provided at an interval in the longitudinal direction of the sealing plate 2 at the end of the electrode assembly 3 facing the sealing plate 2. The positive electrode tab group 40A is electrically connected to the positive electrode terminal 7 via a first 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 8a and a second negative electrode current collector 8b.

[0021] 8, the electrode body 3 is composed of a first electrode body element 3a and a second electrode body element 3b, each of which is composed of a plurality of positive electrode plates 4 and negative electrode plates 5 stacked with separators interposed between them. These two electrode body elements 3a, 3b have the same structure. The first electrode body element 3a includes a first positive electrode tab group 40A1 and a first negative electrode tab group 50A1, and the second electrode body element 3b includes a second positive electrode tab group 40A2 and a second negative electrode tab group 50A2.

[0022] As shown in FIGS. 6 and 13, the first positive electrode current collector 6a is formed in the shape of a plate substantially parallel to the sealing plate 2. More specifically, a step 6c is formed on the first positive electrode current collector 6a near one longitudinal end of the sealing plate 2 (the end opposite the negative electrode terminal 9), and the region of the first positive electrode current collector 6a closer to the other longitudinal end of the sealing plate 2 than the step 6c constitutes a main plate 6d, while the region of the first longitudinal end of the sealing plate 2 closer to the step 6c constitutes an electrode body side plate 6e located closer to the electrode body 3 than the main plate 6d. A current collector through-hole 6f is formed in the main plate 6d at a position facing the electrolyte injection hole 15 in the sealing plate 2. A thin-walled portion 6g is formed in the electrode body side plate 6e.

[0023] The second positive electrode current collector 6b is formed in the shape of a plate that is approximately parallel to the sealing plate 2.

[0024] The thin portion 6g of the electrode body side plate portion 6e of the first positive electrode current collector 6a is integrally welded to the second positive electrode current collector 6b from the side of the electrode body 3. The first positive electrode current collector 6a and the second positive electrode current collector 6b constitute the positive electrode current collector 6.

[0025] The first positive electrode current collector 6a, the second positive electrode current collector 6b, and the positive electrode terminal 7 are preferably made of metal, and more preferably made of aluminum or an aluminum alloy.

[0026] An external insulating member 10 made of resin is disposed between the positive terminal 7 and the sealing plate 2. A first internal insulating member 18 is disposed on the battery interior side (electrode body 3 side) around the positive terminal insertion hole 2a of the sealing plate 2. The first internal insulating member 18 abuts against the sealing plate 2 from the battery interior side. A through hole for inserting the positive terminal 7 is formed in the external insulating member 10 and the first internal insulating member 18 in a portion corresponding to the positive terminal insertion hole 2a of the sealing plate 2. A cup-shaped conductive member 65 is disposed on the battery interior side (electrode body 3 side) of the first internal insulating member 18, with its opening facing the battery interior side. A terminal connection hole is formed through the conductive member 65. A disk-shaped deformable plate 66 is disposed on the battery interior side of the conductive member 65 so as to close the opening of the conductive member 65. The periphery of the deformable plate 66 is welded to the conductive member 65, thereby sealing the opening of the conductive member 65. The conductive member 65 and the deformable plate 66 are preferably made of metal, and more preferably made of aluminum or an aluminum alloy.

[0027] A second internal insulating member 11 made of resin is disposed between the first positive electrode current collector 6a, the second positive electrode current collector 6b, and the sealing plate 2. The second internal insulating member 11 abuts around the electrolyte injection hole 15 of the sealing plate 2 and against the deformation plate 66 from the inside of the battery. A liquid injection opening 11a is provided in the second internal insulating member 11 at a portion facing the electrolyte injection hole 15 of the sealing plate 2. A cylindrical portion 11b protrudes toward the inside of the battery from the edge of the liquid injection opening 11a. Furthermore, opening cover portions 11c are provided that protrude from two points on the edge of the cylindrical portion 11b toward the inside of the battery and connect the two points in a bridge-like manner. A through-hole that overlaps with a portion of the deformation plate 66 is also formed in the second internal insulating member 11.

[0028] As shown in Fig. 8, the leading end of the first positive electrode tab group 40A1 and the leading end of the second positive electrode tab group 40A2 are welded to two regions that sandwich the current collector through-hole 6f on either side of the short side of the sealing plate 2 in the surface of the main plate portion 6d of the first positive electrode current collector 6a facing the electrode body 3. That is, the welded region of the leading end of the first positive electrode tab group 40A1 and the welded region of the leading end of the second positive electrode tab group 40A2 are spaced apart in the short side of the sealing plate 2, with the current collector through-hole 6f in between. In Fig. 8, the leading end of the first positive electrode tab group 40A1, i.e., the welded portion, is indicated by reference symbol 60a, and the leading end of the second positive electrode tab group 40A2, i.e., the welded portion, is indicated by reference symbol 60b. 11 , the welded portions 60a, 60b of the first positive electrode tab group 40A1 and the second positive electrode tab group 40A2 and an area of ​​the surface of the first positive electrode current collector 6a facing the electrode body 3, sandwiched between these welded portions 60a, 60b from both sides in the lateral direction of the sealing plate 2, are covered from the electrode body 3 side by a first tape 81 serving as an electrode body-side covering member. Both ends of the first tape 81 in the lateral direction of the sealing plate 2 are attached to the welded portions 60a, 60b of the first positive electrode tab group 40A1 and the second positive electrode tab group 40A2. Meanwhile, a midpoint of the first tape 81 in the lateral direction of the sealing plate 2 has gaps between it and the current collector through-hole 6f of the first positive electrode current collector 6a, the liquid injection opening 11a and opening cover portion 11c of the second inner insulating member 11, and the electrolyte injection hole 15 of the sealing plate 2.

[0029] 15, areas on the surface of the main plate portion 6d of the first positive electrode current collector 6a facing the sealing plate 2, which correspond to the rear sides of the welded areas of the first positive electrode tab group 40A1 and the second positive electrode tab group 40A2, are covered with rectangular second tapes 82 serving as sealing plate-side covering members. The entire second tape 82 is attached to the first positive electrode current collector 6a.

[0030] Additionally, a third tape 83 is attached to the electrode body side plate portion 6e of the first positive electrode current collector 6a from the electrode body 3 side to cover the welded portion of the first positive electrode current collector 6a to the second positive electrode current collector 6b.

[0031] As shown in FIGS. 7 and 14, the first negative electrode current collector 8a is formed in a plate shape substantially parallel to the sealing plate 2. Specifically, a step 8c is formed on the first negative electrode current collector 8a near one longitudinal end of the sealing plate 2 (the end opposite the positive electrode terminal 7). The region of the first negative electrode current collector 8a closer to the other longitudinal end of the sealing plate 2 than the step 8c constitutes a first plate-shaped portion 8d, and the region of the first longitudinal end of the sealing plate than the step 8c constitutes a second plate-shaped portion 8e located closer to the electrode body 3 than the first plate-shaped portion 8d. The surface of the first plate-shaped portion 8d facing the sealing plate 2 constitutes a first region RE1, and the surface of the second plate-shaped portion 8e facing the sealing plate 2 constitutes a second region RE2 located closer to the electrode body 3 than the first region RE1. In FIG. 14, the step between the first region RE1 and the second region RE2 is indicated by the symbol D. A recess 8f is formed on the surface of the second plate-shaped portion 8e facing the electrode body 3, recessed toward the sealing plate 2. A thin portion 8g is formed in the recess 8f.

[0032] The second negative electrode current collector 8b is formed in the shape of a plate that is approximately parallel to the sealing plate 2. A terminal connection hole is formed in the second negative electrode current collector 8b. In Fig. 14, the thickness of the second negative electrode current collector 8b is indicated by the symbol T1.

[0033] The second negative electrode current collector 8b is integrally welded to the thin portion 8g (second region RE) of the second plate-shaped portion 8e of the first negative electrode current collector 8a, and the surface of the second negative electrode current collector 8b facing the electrode body 3 abuts against the second region RE2 of the first negative electrode current collector 8a. The first negative electrode current collector 8a and the second negative electrode current collector 8b constitute the negative electrode current collector 8.

[0034] 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 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 that the portion made of aluminum or an aluminum alloy protrudes outward beyond the sealing plate 2.

[0035] 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. The internal insulating member 13 is fixed in a state in contact with the sealing plate 2 from the inside of the battery. Through holes are formed in the external insulating member 12 and the internal insulating member 13 at positions corresponding to the negative electrode terminal insertion hole 2b of the sealing plate 2.

[0036] A flat flat region FRE is formed on the surface of inner insulating member 13 facing the electrode body 3. The surface of second negative electrode current collector 8b facing the sealing plate 2 abuts against this flat region FRE.

[0037] The leading end of the first negative electrode tab group 50A1 and the leading end of the second negative electrode tab group 50A2 are each welded to the surface of the first plate-shaped portion 8d of the first negative electrode current collector 8a facing the electrode body 3. In other words, the welded region of the leading end of the first negative electrode tab group 50A1 and the welded region of the leading end of the second negative electrode tab group 50A2 are spaced apart in the short-side direction of the sealing plate 2. In Fig. 8, the leading end of the first negative electrode tab group 50A1, i.e., the welded portion, is indicated by reference numeral 61a, and the leading end of the second negative electrode tab group 50A2, i.e., the welded portion, is indicated by reference numeral 61b. The leading end portions of the first negative electrode tab group 50A1 and the second negative electrode tab group 50A2, i.e., the welded portions 61a, 61b of the first negative electrode tab group 50A1 and the second negative electrode tab group 50A2, an area on the electrode body 3 side surface of the first plate-shaped portion 8d sandwiched between these welded portions 61a, 61b from both sides in the short direction of the sealing plate 2, and the welded portion of the second plate-shaped portion 8e to the second negative electrode current collector 8b are covered from the electrode body 3 side by a single fourth tape 84 serving as an electrode body side covering member. The fourth tape 84 is attached to the welded portions 61a, 61b of the first negative electrode tab group 50A1 and the second negative electrode tab group 50A2 and to an area of ​​the second plate-shaped portion 8e where the recess 8f is not formed.

[0038] Furthermore, a fifth tape 85 is attached as a sealing plate-side covering member to the entire surface of the first plate-shaped portion 8d of the first negative electrode current collector 8a facing the sealing plate 2, i.e., the first region RE1, excluding the outer peripheral edge. The fifth tape 85 covers two regions that correspond to the backsides of the welding regions of the first negative electrode tab group 50A1 and the second negative electrode tab group 50A2 on the surface (first region RE1) facing the sealing plate 2 of the first plate-shaped portion 8d of the first negative electrode current collector 8a.

[0039] The first to fifth tapes 81 to 85 are composed of a base material made of a polypropylene film and an adhesive layer made of a rubber-based adhesive applied to one side of the polypropylene film. The first to fifth tapes 81 to 85 have the same thickness. In FIG. 14, the thickness of the fifth tape 85 is indicated by the symbol T2. The thickness T1 of the second negative electrode current collector 8b is set to be larger than the sum of the step D between the first region RE1 and the second region RE2 of the first negative electrode current collector 8a and the thickness T2 of the fifth tape 85.

[0040] An electrode assembly holder 14 made of a resin sheet is disposed between the electrode assembly 3 and the rectangular outer casing 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 electrical insulation between the electrode assembly 3 and the rectangular outer casing 1.

[0041] Next, a method for manufacturing the prismatic secondary battery 20 and the details of each component will be described.

[0042] [Positive electrode] First, a method for manufacturing the positive electrode plate 4 will be described.

[0043] [Preparation of Positive Electrode Active Material Mixture Layer Slurry] For example, it is prepared by kneading a positive electrode active material, a conductive agent, and a binder. Examples of the positive electrode active material include lithium composite oxides such as lithium nickel cobalt manganese composite oxide. Examples of the binder include fluororesins such as polyvinylidene fluoride (PVdF). Examples of the conductive agent include carbon materials such as carbon black.

[0044] [Preparation of positive electrode protective layer slurry] Alumina powder, graphite as a conductive agent, polyvinylidene fluoride (PVdF) as a binder, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium are mixed together to prepare a protective layer slurry.

[0045] [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-described method are applied to both sides of a 15 μm thick aluminum foil serving as a positive electrode core using 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.

[0046] 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 the NMP from the slurry. This forms the positive electrode active material mixture layer and the protective layer. The positive electrode active material mixture layer is then compressed by passing it through a pair of press rollers to form a positive electrode base plate. This positive electrode base plate is cut to a predetermined size to produce the positive electrode plate 4 shown in FIG. 3. The positive electrode plate 4 is rectangular, with a positive electrode tab 40 protruding from the top edge. A narrow positive electrode protective layer 4c is formed along the top edge of the positive electrode plate 4, and a positive electrode active material mixture layer 4b is formed from below the positive electrode protective layer 4c to the bottom edge 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 4 to form the positive electrode tab 40.

[0047] [Negative electrode] Next, a method for manufacturing the negative electrode plate 5 will be described.

[0048] [Preparation of negative electrode active material mixture layer slurry] It is prepared by kneading 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).

[0049] [Formation of negative electrode active material mixture layer] The negative electrode active material mixture layer slurry prepared by the method described above is applied to both sides of a copper foil having a thickness of 8 μm as a negative electrode substrate using a die coater.

[0050] 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 core is then passed through a pair of press rollers to compress the negative electrode active material mixture layer into a negative electrode base plate. This negative electrode base plate is cut to a predetermined size to create the negative electrode plate 5 shown in FIG. 4. The negative electrode plate 5 is rectangular, with a negative electrode tab 50 protruding from the top edge. A negative electrode active material mixture layer 5b is formed on the entire surface of the negative electrode core excluding the negative electrode tab 50. Note that the negative electrode tab 50 may be formed from the negative electrode core as described above, or a separate member may be connected to the negative electrode plate 5 to form the negative electrode tab 50.

[0051] [Preparation of electrode body] A plurality of positive electrode plates 4 and negative electrode plates 5 prepared by the above-described method are stacked with separators interposed therebetween to produce a stacked electrode assembly 3. The number of positive electrode plates 4 and negative electrode plates 5 included in the electrode assembly 3 is not particularly limited, but several tens or more are preferred. Specifically, the electrode assembly 3 is prepared from a first electrode assembly element 3a and a second electrode assembly element 3b.

[0052] [Connection between current collector and tab] Then, as shown in FIG. 8, 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 welded to one surface of the main plate portion 6d of the first positive electrode current collector 6a (positive electrode current collector 6) shown in FIG. 6, 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 welded to one surface of the first plate-shaped portion 8d of the first negative electrode current collector 8a (negative electrode current collector 8) shown in FIG. 7.

[0053] The welding connection between the positive electrode tab group 40A and the first positive electrode current collector 6a and the welding 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 welding connection is performed by ultrasonic welding.

[0054] 15 , two second tapes 82 are attached to the other surface of the main plate portion 6d of the first positive electrode current collector 6a, and a fifth tape 85 is attached to the other surface of the first plate portion 8d of the first negative electrode current collector 8a. This allows the second tape 82 to capture foreign matter adhering to the surface of the first positive electrode current collector 6a opposite the connection surface of the positive electrode tab group 40A, particularly metal powder generated during the welding process of the positive electrode tab group 40A, thereby preventing the foreign matter from entering the electrode assembly 3. Similarly, the fifth tape 85 captures foreign matter adhering to the surface of the first negative electrode current collector 8a opposite the connection surface of the negative electrode tab group 50A, particularly metal powder generated during the welding process of the negative electrode tab group 50A, thereby preventing the foreign matter from entering the electrode assembly 3. This significantly reduces the occurrence of internal short circuits due to foreign matter.

[0055] [Installing each part on the sealing plate] 9 is a view showing the surface of the sealing plate 2 on the inner side of the battery, to which the various components have been attached. The attachment of the various components to the sealing plate 2 will be described with reference to FIGS.

[0056] An external insulating member 10 is placed around the positive terminal insertion hole 2a of the sealing plate 2. A first internal insulating member 18 and a cup-shaped conductive member 65 are placed on the inner surface of the battery around the positive terminal insertion hole 2a of the sealing plate 2. Then, a positive terminal 7 is inserted from the outside of the battery through the through hole of the external insulating member 10, the positive terminal insertion hole 2a of the sealing plate 2, the through hole of the first internal insulating member 18, 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. This fixes the positive terminal 7 and the conductive member 65 to the sealing plate 2. Note that it is preferable to connect the crimped portion of the positive terminal 7 to the conductive member 65 by welding.

[0057] Furthermore, a disk-shaped deformable plate 66 is placed so as to close the opening of the conductive member 65, and the periphery of the deformable plate 66 is welded to the conductive member 65. This seals the opening of the conductive member 65. Next, a second internal insulating member 11 made of resin is placed around the electrolyte injection hole 15 of the sealing plate 2 and on the electrode body 3 side of the deformable plate 66. Then, the second positive electrode current collector 6b is placed on the battery interior side of the second internal insulating member 11, and the deformable plate 66 and the second positive electrode current collector 6b are welded together through the through hole in the second internal insulating member 11.

[0058] Meanwhile, an external insulating member 12 is placed on the outer surface of the battery around the negative terminal insertion hole 2b of the sealing plate 2. An internal insulating member 13 and a second negative electrode current collector 8b are placed on the inner surface of the battery around the negative terminal insertion hole 2b of the sealing plate 2. Then, a negative electrode terminal 9 is inserted from the outside of the battery through the through hole of the external insulating member 12, the negative electrode terminal insertion hole 2b 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. This fixes the negative electrode terminal 9 and the second negative electrode current collector 8b to the sealing plate 2. Note that the crimped portion of the negative electrode terminal 9 is preferably connected to the second negative electrode current collector 8b by welding.

[0059] [Connection between the first and second current 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, 40A2 are connected, is placed on the second internal insulating member 11 so that a portion of the first positive electrode current collector 6a (electrode body side plate portion 6e) overlaps the second positive electrode current collector 6b. The first positive electrode current collector 6a and the second positive electrode current collector 6b are welded together by irradiating the thin-walled portion 6g with a laser. The first negative electrode current collector 8a, to which the first and second negative electrode tab groups 50A1, 50A2 are connected, is placed on the internal insulating member 13 so that a portion of the first negative electrode current collector 8a (second plate-shaped portion 8e) overlaps the second negative electrode current collector 8b. The thin-walled portion 8g is then irradiated with a laser so that the first negative electrode current collector 8a and the second negative electrode current collector 8b are welded together. 14, the thickness T1 of the second negative electrode current collector 8b is set to be larger than the sum of the step D between the first region RE1 and the second region RE2 of the first negative electrode current collector 8a and the thickness T2 of the fifth tape 85, so that the second plate-shaped portion 8e of the first negative electrode current collector 8a is less likely to lift up from the second negative electrode current collector 8b. This makes it possible to more reliably weld the first negative electrode current collector 8a and the second negative electrode current collector 8b together.

[0061] In this embodiment, the first positive electrode current collector 6a and the second positive electrode current collector 6b are connected by laser welding, but they may also be connected by ultrasonic welding, resistance welding, or the like.

[0062] 11 , a first tape 81 is attached to the welded portions 60a, 60b so as to cover the welded portions 60a, 60b of the first positive electrode tab group 40A1 and the second positive electrode tab group 40A2 and the area of ​​the surface of the first positive electrode current collector 6a facing the electrode body 3 that is sandwiched between the welded portions 60a, 60b from both sides in the short direction of the sealing plate 2. In this way, the first tape 81 can capture foreign matter present around the welded portions 60a, 60b, in particular metal powder generated during the welding process of the positive electrode tab group 40A, and can prevent the foreign matter from entering the inside of the electrode body 3. This can significantly prevent the occurrence of internal short circuits due to foreign matter.

[0063] Furthermore, a third tape 83 is attached to the surface of the electrode body side plate portion 6e of the first positive electrode current collector 6a facing the electrode body 3 so as to cover the welded portion of the first positive electrode current collector 6a to the second positive electrode current collector 6b. This allows the third tape 83 to capture foreign matter present around the welded portion of the first positive electrode current collector 6a to the second positive electrode current collector 6b, particularly metal powder generated during the welding process of the first positive electrode current collector 6a and the second positive electrode current collector 6b, and to prevent the foreign matter from entering the inside of the electrode body 3. This significantly reduces the occurrence of internal short circuits due to foreign matter.

[0064] Furthermore, a fourth tape 84 is attached to the welded portions 61a, 61b of the first negative electrode tab group 50A1 and the second negative electrode tab group 50A2 and to the region where the recess 8f is not formed of the second plate-shaped portion 8e from the electrode body 3 side so as to cover the welded portions 61a, 61b of the first negative electrode tab group 50A1 and the second negative electrode tab group 50A2, an area on the electrode body 3 side surface of the first negative electrode current collector 8a sandwiched between these welded portions 61a, 61b from both sides in the short direction of the sealing plate 2, and the welded portion of the first negative electrode current collector 8a to the second negative electrode current collector 8b. This allows the fourth tape 84 to capture foreign matter present around the welded portions 61a, 61b, particularly metal powder generated during the welding process of the negative electrode tab group 50A, and to prevent the foreign matter from entering the electrode body 3. This significantly reduces the occurrence of internal short circuits due to foreign matter.

[0065] Furthermore, because the fourth tape 84 also covers the welded portion of the first negative electrode current collector 8a to the second negative electrode current collector 8b, the fourth tape 84 can capture foreign matter present around the welded portion of the first negative electrode current collector 8a to the second negative electrode current collector 8b, particularly metal powder generated in the welding process of the first negative electrode current collector 8a and the second negative electrode current collector 8b, and can prevent foreign matter from entering the inside of the electrode body 3. This can significantly prevent the occurrence of internal short circuits due to foreign matter.

[0066] Then, as shown in FIG. 12, the entire second positive electrode current collector 6b, the electrode body side plate portion 6e of the first positive electrode current collector 6a, and the third tape 83 are covered with a cover member 88.

[0067] In this embodiment, the base material of the first to fifth tapes 81 to 85 is made of polypropylene film, but it may be made of a plastic film other than polypropylene film.

[0068] Furthermore, instead of the first to fifth tapes 81 to 85, a coating material such as a sealing resin that hardens with heat or light may be used as a covering member, or an adhesive sheet using metal foil or nonwoven fabric may be used.

[0069] Moreover, instead of the first to fifth tapes 81 to 85, a sheet or cushion material without an adhesive layer may be provided.

[0070] [Secondary battery production] Next, the two positive electrode tab groups 40A1, 40A2 and the two negative electrode tab groups 50A1, 50A2 are bent 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 with each other directly or via another member. This combines the two electrode body elements 3a, 3b into a single 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.

[0071] The electrode body 3 wrapped in the electrode body holder 14 is inserted into the prismatic outer casing 1. Then, the sealing plate 2 and the prismatic outer casing 1 are welded together, and the opening of the prismatic outer casing 1 is sealed with the sealing plate 2. Then, electrolyte is poured into the prismatic outer casing 1 through an electrolyte pouring hole 15 provided in the sealing plate 2. After that, the electrolyte pouring hole 15 is sealed with a sealing member such as a blind rivet. This completes the prismatic secondary battery 20.

[0072] (Other embodiments) The above-described embodiments are merely examples of the present invention, and the present invention is not limited to these examples. These examples may be combined with well-known, commonly used, or publicly known technologies, or may be partially replaced. Modified inventions that would be easily conceived by a person skilled in the art are also included in the present invention.

[0073] The electrode body 3 may have a structure in which the positive electrode plate 4, the negative electrode plate 5, and a separator are stacked and then wound. The electrode body elements 3a and 3b may also have a wound structure.

[0074] In the above embodiment, an example was shown in which two electrode elements 3a and 3b were arranged inside the rectangular exterior housing 1, but the number of electrode elements may be one, or three or more.

[0075] In the above-described embodiment, an example has been shown in which the positive electrode current collector 6 and the negative electrode current collector 8 each consist of two parts, but the positive electrode current collector 6 and the negative electrode current collector 8 may each consist of a single part.

[0076] In the above embodiment, the tab portion is provided on both the positive electrode plate 4 and the negative electrode plate 5, but it may be provided on only one of them.

[0077] Known materials can be used for the positive electrode plate 4, the negative electrode plate 5, the separator, the electrolyte, and the like. [Explanation of symbols]

[0078] 1. Exterior body 2 Sealing plate 3 Electrode body 4 positive electrode plate 5 negative electrode plate 6 Positive electrode current collector 7 Positive terminal 8 Negative electrode current collector 8a 1st negative electrode current collector 8b Second negative electrode current collector 9 Negative terminal 13 Inner insulating member 40 Positive electrode tab (tab part) 50 Negative electrode tab (tab part) 81 First tape (electrode body side covering member) 82 Second tape (sealing plate side covering member) 84 Fourth tape (electrode body side covering member) 85 Fifth tape (sealing plate side covering member) FRE flat region RE1 1st area RE2, Second Domain

Claims

1. an electrode assembly in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween, and a tab portion is provided on at least one of the positive electrode plate and the negative electrode plate; an exterior body having an opening and accommodating the electrode body; a sealing plate that seals the opening; an external terminal attached to the sealing plate; a substantially plate-shaped current collector disposed between the electrode body and the sealing plate and substantially parallel to the sealing plate, and electrically connected to the external terminal; a battery including an insulating member provided between the current collector and the sealing plate, a tab portion of the electrode body is welded to a surface of the current collector facing the electrode body; a sealing plate-side covering member is attached to a region of the surface of the current collector facing the sealing plate, the region corresponding to a rear side of the welding region of the tab portion; the sealing plate side covering member is provided between the current collector and the insulating member, The battery is characterized in that the insulating member overlaps the welding area of ​​the tab portion in the direction in which the tab portion, the current collector, and the sealing plate side covering member are aligned.

2. An electrode assembly in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween, and a tab portion is provided on at least one of the positive electrode plate and the negative electrode plate; an exterior body having an opening and accommodating the electrode body; a sealing plate that seals the opening; an external terminal attached to the sealing plate; a substantially plate-shaped current collector disposed between the electrode body and the sealing plate and substantially parallel to the sealing plate, and electrically connected to the external terminal, a tab portion of the electrode body is welded to a surface of the current collector facing the electrode body; a sealing plate-side covering member is attached to a region of the surface of the current collector facing the sealing plate, the region corresponding to a rear side of the welding region of the tab portion; A battery characterized in that the welded portion of the tab portion to the current collector is covered with an electrode body side covering member.

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