Secondary battery

Abstract

The secondary battery comprises: an electrode body in which a positive electrode plate and a negative electrode plate are stacked with a separator between them; an outer body having an opening and accommodating the electrode body; a sealing plate for sealing the opening; and an external terminal mounted on the sealing plate, wherein joints provided on the positive electrode plate and the negative electrode plate are electrically connected to the external terminal via a current collector arranged between the electrode body and the sealing plate, the current collector having a first connecting portion connected to the joint and a second connecting portion having a fuse portion, the fuse portion being a portion that melts when an overcurrent flows in the current path by minimizing a cross-sectional area orthogonal to a current direction in a current path from the joint to the external terminal, and a portion of the fuse portion that is opposite to the electrode body is covered by a fuse portion insulating member formed of a material having a melting point of 200°C or more.

Description

Technical Field

[0001] The present disclosure relates to a secondary battery. Background Art

[0002] Prismatic secondary batteries such as alkaline secondary batteries and non-aqueous electrolyte secondary batteries are used as power sources for driving electric vehicles (EVs), hybrid electric vehicles (HEVs, PHEVs), and the like.

[0003] In these square secondary batteries, the battery case is formed by a square outer body with a bottomed cylindrical shape having an opening and a sealing plate that seals the opening. The electrode body consisting of a positive plate, a negative plate, and a separator is housed in the battery case together with the electrolyte. A positive terminal and a negative terminal are mounted on the sealing plate. The positive terminal is electrically connected to the positive plate via the positive electrode collector, and the negative terminal is electrically connected to the negative plate via the negative electrode collector.

[0004] Furthermore, in order to prevent an overcurrent from flowing through a secondary battery and damaging the battery, it has been proposed to provide a fuse on a current collector that electrically connects a terminal to an electrode body.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-219003 Summary of the Invention

[0008] -Problems to be solved by the invention-

[0009] In the structure of Patent Document 1, the guide member guides the gas generated in the fuse area to move toward the first short-circuit member. However, in this structure, if the fuse area is blown due to overcurrent, there is a concern that the guide member may be destroyed due to the sparks and heat generated, causing damage to the electrode body and generating an internal short circuit.

[0010] -Methods for solving the problem-

[0011] The secondary battery disclosed herein has the following structure, namely, it comprises: an electrode body, in which positive and negative plates are stacked with separators interposed therebetween; an outer body having an opening and accommodating the electrode body; a sealing plate for sealing the opening; and an external terminal mounted on the sealing plate, wherein a tab provided on at least one of the positive and negative plates is electrically connected to the external terminal via a current collector arranged between the electrode body and the sealing plate, the current collector comprising: a first connecting portion to which the tab or a tab conductive member connected to the tab is connected; and a second connecting portion comprising a fuse portion, the fuse portion being a portion that melts when an overcurrent flows in the current path by minimizing a cross-sectional area perpendicular to a current direction in the current path from the tab to the external terminal, the portion of the fuse portion facing the electrode body being covered by a fuse portion insulating member, the fuse portion insulating member being a member made of a material having a melting point of 200°C or higher.

[0012] The fuse portion insulating member may support the fuse portion while in contact with the fuse portion.

[0013] The fuse portion insulating member may also cover a portion of the second connecting portion adjacent to the fuse portion.

[0014] A sealing plate-current collector insulating member may be disposed between the sealing plate and the current collector, and the fuse insulating member may be supported by the sealing plate-current collector insulating member.

[0015] Alternatively, an external terminal protection insulating member may be arranged between the electrode body and the side of the external terminal facing the electrode body, and a sealing plate-collector insulating member may be arranged between the sealing plate and the collector, and the external terminal protection insulating member may be supported by the sealing plate-collector insulating member.

[0016] Alternatively, the outer body may be square, the first connecting portion may be located further inward in the long side direction of the sealing plate than the second connecting portion, the second connecting portion may have a terminal side connecting portion connected to the external terminal or to an external terminal conductive member, the external terminal conductive member may be connected to the external terminal, and the fuse portion may be located further outward in the long side direction of the sealing plate than the terminal side connecting portion.

[0017] -Effects of the Invention-

[0018] According to the present disclosure, a highly reliable secondary battery can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic perspective view of a secondary battery according to one embodiment.

[0020] Figure 2 It is along Figure 1 Schematic cross-sectional view of line AA in FIG.

[0021] Figure 3 It is a schematic top view of the positive electrode plate.

[0022] Figure 4 is a schematic top view of the negative electrode plate.

[0023] Figure 5 It is a schematic top view of the electrode body elements.

[0024] Figure 6 This is a schematic diagram showing a state in which a positive electrode tab group is connected to a positive electrode current collector and a negative electrode tab group is connected to a negative electrode current collector according to one embodiment.

[0025] Figure 7 This is a schematic diagram of a sealing plate assembled with various components according to one embodiment, as viewed from the electrode body side.

[0026] Figure 8 This is a schematic perspective view of a positive electrode current collector according to one embodiment.

[0027] Figure 9 This is a schematic perspective cross-sectional view of a positive electrode terminal portion of a sealing plate according to one embodiment, as viewed from the electrode body side.

[0028] Figure 10 This is a schematic cross-sectional view of a positive electrode terminal portion of a sealing plate according to another embodiment, as viewed from the electrode body side. DETAILED DESCRIPTION

[0029] The following describes embodiments of the present disclosure in detail based on the accompanying drawings. The following description of preferred embodiments is essentially illustrative and is not intended to limit the present disclosure, its applications, or its uses. In the following drawings, for simplicity of description, the same reference numerals are used to represent structural elements having substantially the same functions.

[0030] (Implementation 1)

[0031] The structure of a prismatic secondary battery 20 as the secondary battery according to the first embodiment will be described below.

[0032] like Figure 1 as well as Figure 2As shown, the square secondary battery 20 has a battery case 100, which is composed of a square outer body 1 with an open bottom and a sealing plate 2 that seals the opening of the square outer body 1. The square outer body 1 and the sealing plate 2 are preferably made of metal, for example, preferably made of aluminum or an aluminum alloy. The electrode body 3 formed by stacking the positive electrode plate and the negative electrode plate with a separator is housed in the square outer body 1 together with the electrolyte. In this embodiment, as described later, the electrode body 3 includes a first electrode body element and a second electrode body element, and the two electrode body elements have the same structure.

[0033] The sealing plate 2 is provided with an electrolyte injection hole 15, which is sealed with a sealing member 16. The sealing plate 2 is provided with a gas discharge valve 17 that ruptures when the pressure inside the battery case 100 exceeds a predetermined value, thereby discharging the gas inside the battery case 100 to the outside of the battery case 100. An annular protrusion 2c is provided on the surface of the sealing plate 2 facing the interior of the battery, surrounding the gas discharge valve 17.

[0034] A positive electrode tab group 40b and a negative electrode tab group 50b are provided at the end of the electrode body 3 on the sealing plate 2 side. The positive electrode tab group 40b is electrically connected to the positive electrode terminal (external terminal) 7 via the positive electrode current collector 6b and the positive electrode terminal conductive member (external terminal conductive member) 6a. The negative electrode tab group 50b is electrically connected to the negative electrode terminal (external terminal) 9 via the negative electrode current collector 8b and the negative electrode terminal conductive member (external terminal conductive member) 8a.

[0035] The positive electrode current collector 6b, the positive electrode terminal conductive member 6a, and the positive electrode terminal 7 are preferably made of metal, more preferably aluminum or an aluminum alloy. A resin external insulating member 10 is disposed between the positive electrode terminal 7 and the sealing plate 2. A resin internal insulating member (seal plate-current collector insulating member) 11 is disposed between the positive electrode current collector 6b and the positive electrode terminal conductive member 6a and the sealing plate 2.

[0036] The negative electrode current collector 8b, the negative electrode terminal conductive member 8a, and the negative electrode terminal 9 are preferably made of metal, more preferably copper or a copper alloy. A resin outer insulating member 12 is disposed between the negative electrode terminal 9 and the sealing plate 2. A resin inner insulating member 13 is disposed between the negative electrode current collector 8b and the negative electrode terminal conductive member 8a and the sealing plate 2.

[0037] An electrode body holder 14 made of a resin sheet is disposed between the electrode body 3 and the rectangular outer package 1. The electrode body holder 14 is preferably a member formed by bending a resin insulating sheet into a bag or box shape.

[0038] Next, a method for manufacturing the rectangular secondary battery 20 and details of each structure will be described.

[0039] [Positive plate]

[0040] Figure 3 It is a top view of the positive electrode plate 4. The positive electrode plate 4 has a main body portion in which positive electrode active material mixture layers 4b including a positive electrode active material are formed on both sides of a rectangular positive electrode core. The positive electrode core protrudes from the end side of the main body portion, and the protruding positive electrode core constitutes a positive electrode connector 40. In addition, the positive electrode connector 40 can be a part of the positive electrode core, or other components can be connected to the positive electrode core to serve as the positive electrode connector 40. In addition, a positive electrode protective layer 4c having a resistance greater than that of the positive electrode active material mixture layer 4b is preferably provided in a portion of the positive electrode connector 40 adjacent to the positive electrode active material mixture layer 4b. In addition, as the positive electrode core, metal foil such as aluminum foil and aluminum alloy foil is preferably used. As the positive electrode active material, lithium transition metal composite oxide or the like is preferably used.

[0041] [Negative plate]

[0042] Figure 4 This is a top view of the negative electrode plate 5. The negative electrode plate 5 has a main body portion having negative electrode active material mixture layers 5b containing a negative electrode active material formed on both sides of a rectangular negative electrode core. The negative electrode core protrudes from the end edge of the main body portion, and the protruding negative electrode core constitutes a negative electrode connector 50. In addition, the negative electrode connector 50 can be a part of the negative electrode core, or other components can be connected to the negative electrode core to serve as the negative electrode connector 50. In addition, as the negative electrode core, metal foil such as copper foil and copper alloy foil is preferably used. As the negative electrode active material, carbon materials, silicon-containing materials, etc. are preferably used.

[0043] [Production of Electrode Body]

[0044] Make 50 positive plates 4 and 51 negative plates 5, as shown in the following example: Figure 5 As shown, these are stacked with a square separator made of polyethylene to produce a stacked first electrode body element 3a. In addition, the second electrode body element also has the same structure / construction. The stacked first electrode body element 3a has a first positive terminal group 40a formed by stacking the positive terminals 40 of each positive electrode plate 4 and a first negative terminal group 50a formed by stacking the negative terminals 50 of each negative electrode plate 5 at one end. Separators are arranged on both outer surfaces of the first electrode body element 3a, and by winding an adhesive tape or the like on the outer peripheral surface of the first electrode body element electrode body 3a, it is possible to fix the plates and separators in a stacked state. Alternatively, an adhesive layer can be provided on the surface of the separator so that the separator is bonded to the positive electrode plate 4 and the separator is bonded to the negative electrode plate 5, respectively.

[0045] In addition, the size of the separator in a plan view is preferably the same as that of the negative electrode plate 5, or larger than that of the negative electrode plate 5. It is also possible to arrange the positive electrode plate 4 or the negative electrode plate 5 between the two separators, and after the periphery of the separator is heat-fused, the positive electrode plate 4 and the negative electrode plate 5 are stacked. Alternatively, a long strip of separator can be folded into a zigzag shape, and the positive electrode plate 4 and the negative electrode plate 5 are alternately sandwiched and stacked between each folded section to form an electrode body. In addition, a strip-shaped positive electrode plate and a strip-shaped negative electrode plate can be wound with a strip-shaped separator between them to form a wound electrode body.

[0046] [Connection between current collector and connector]

[0047] Figure 6 This diagram shows a state where the first positive electrode terminal group 40a of the first electrode body element 3a and the second positive electrode terminal group 40b of the second electrode body element 3b are connected to the positive electrode current collector 6b, and the first negative electrode terminal group 50a of the first electrode body element 3a and the second negative electrode terminal group 50b of the second electrode body element 3b are connected to the negative electrode current collector 8b. The positive electrode current collector 6b has a structure where a first connecting portion 6c and a second connecting portion 6f are connected via a connecting portion 6e. The negative electrode current collector 8b has a structure where a first connecting portion 8c and a second connecting portion 8f are connected via a connecting portion 8e.

[0048] like Figure 6 In this way, the first electrode body element 3a and the second electrode body element 3b are arranged so that the front ends of the first positive terminal group 40a and the second positive terminal group 40b, and the front ends of the first negative terminal group 50a and the second negative terminal group 50b face each other. Moreover, the first positive terminal group 40a and the second positive terminal group 40b are arranged on the first connection portion 6c of the positive electrode collector 6b. In addition, the first negative terminal group 50a and the second negative terminal group 50b are arranged on the first connection portion 8c of the negative electrode collector 8b. The first positive terminal group 40a and the second positive terminal group 40b are respectively welded to the first connection portion 6c to form a weld portion 60. Similarly, the first negative terminal group 50a and the second negative terminal group 50b are respectively welded to the first connection portion 8c to form a weld portion 61. The welding method is preferably ultrasonic welding or resistance welding. In addition, laser welding can also be used for connection.

[0049] [Structure of the sealing plate]

[0050] Figure 7 This is a view of the sealing plate 2 after installing the positive terminal 7, the external insulating component on the positive electrode side (not shown), the internal insulating component 11 on the positive electrode side, the positive terminal conductive component 6a, the negative terminal 9, the external insulating component on the negative electrode side (not shown), the internal insulating component 13 on the negative electrode side and the negative terminal conductive component 8a as viewed from the side of the electrode body 3.

[0051] The sealing plate 2, the external insulating member on the positive electrode side, the internal insulating member 11 on the positive electrode side, the positive electrode terminal conductive member 6a, the external insulating member on the negative electrode side, the internal insulating member 13 on the negative electrode side, and the negative electrode terminal conductive member 8a respectively have through holes that can be inserted into the positive terminal 7 and the negative terminal 9.

[0052] The internal insulating member 11 on the positive electrode side has a positive electrode-side base portion 11a arranged parallel to the sealing plate 2. Positive electrode-side ribs 11b are provided on the outer periphery of the base portion 11a, protruding from the base portion 11a toward the electrode body 3. The ribs 11b, arranged near both sides of the positive terminal conductive member 6a along the longitudinal direction of the sealing plate 2, are further extended toward the electrode body 3 by wall portions 11c. In other words, the wall portions 11c protrude further from the base portion 11a than the ribs 11b. Furthermore, the wall portions 11c are provided with two types of through-holes, described later. An opening 11d is provided in the base portion 11a to prevent blocking the liquid injection hole 15. Alternatively, if the base portion 11a does not block the liquid injection hole 15, the opening 11d may not be provided.

[0053] The negative electrode internal insulating member 13 has a negative electrode base portion 13a arranged parallel to the sealing plate 2. A negative electrode rib 13b is provided on the outer periphery of the base portion 13a and protrudes from the base portion 13a toward the electrode body 3.

[0054] A protrusion 8x is provided on the surface of the negative electrode terminal conductive member 8a on the electrode body 3 side. The protrusion 8x preferably has a rectangular, elliptical, or a track-shaped shape having a long side and a short side.

[0055] [Assembly of each component to the sealing plate]

[0056] An external insulating member 10 on the positive electrode side is arranged on the outer surface side of the battery around the positive terminal insertion hole provided in the sealing plate 2. An internal insulating member 11 on the positive electrode side and a positive terminal conductive member 6a are arranged on the inner surface side of the battery around the positive terminal insertion hole in the sealing plate 2. Furthermore, the positive terminal 7 is inserted from the outside of the battery into the through-hole of the external insulating member 10 on the positive electrode side, the positive terminal insertion hole of the sealing plate 2, the through-hole of the internal insulating member 11 on the positive electrode side, and the through-hole of the positive terminal conductive member 6a, and the front end of the positive terminal 7 is riveted to the positive terminal conductive member 6a. Thus, the positive terminal 7 and the positive terminal conductive member 6a are fixed to the sealing plate 2. Alternatively, the riveted portion of the positive terminal 7 may be welded to the positive terminal conductive member 6a.

[0057] Next, the negative-electrode external insulating member 12 is placed on the battery's outer surface around the negative-electrode terminal insertion hole of the sealing plate 2. The negative-electrode internal insulating member 13 and the negative-electrode conductive member 8a are placed on the battery's inner surface around the negative-electrode terminal insertion hole of the sealing plate 2. Furthermore, the negative terminal 9 is inserted from the battery's exterior into the through-hole of the negative-electrode external insulating member 12, the negative-electrode terminal insertion hole of the sealing plate 2, the through-hole of the negative-electrode internal insulating member 13, and the through-hole of the negative-electrode conductive member 8a. The tip of the negative terminal 9 is then riveted to the negative-electrode conductive member 8a. Thus, the negative terminal 9 and the negative-electrode conductive member 8a are secured to the sealing plate 2. Alternatively, the riveted portion of the negative terminal 9 can be welded to the negative-electrode conductive member 8a.

[0058] [Positive electrode current collector]

[0059] Figure 8 This is a perspective view of the positive electrode current collector 6b. In this example, the width direction of the positive electrode current collector 6b is defined as being perpendicular to the direction (longitudinal direction) connecting the first connecting portion 6c, the linking portion 6e, and the second connecting portion 6f, and the direction in which the first connecting portion 6c and the second connecting portion 6f extend, and the thickness direction is defined as being perpendicular to both the longitudinal and width directions.

[0060] The first and second positive terminal groups 40a and 40b are connected to the first connecting portion 6c. Alternatively, a terminal conductive member (not shown) connected to the first and second positive terminal groups 40a and 40b can be prepared separately, and the terminal conductive member can be connected to the first connecting portion 6c, and the first and second positive terminal groups 40a and 40b can be electrically connected to the first connecting portion 6c via the terminal conductive member. In addition, an opening 6d is provided so that the injection hole 15 is not blocked by the first connecting portion 6c. In the case of a structure in which the first connecting portion 6c does not block the injection hole 15, the opening 6d can also be omitted.

[0061] The second connection portion 6f includes a terminal-side connection portion 6g and a fuse portion 6h provided between the terminal-side connection portion 6g and the coupling portion 6e.

[0062] In this embodiment, the terminal-side connecting portion 6g is electrically connected to the positive terminal 7 via the positive terminal conductive member 6a, but it may be directly connected to the positive terminal 7. In addition, in order to facilitate the connection between the terminal-side connecting portion 6g and the positive terminal conductive member 6a, the thickness may be thinner than other parts of the positive electrode collector 6b.

[0063] A slit-shaped through-hole 6i extending in the width direction is provided between the terminal-side connection portion 6g and the connecting portion 6e of the second connection portion 6f. Both sides of the through-hole 6i in the width direction serve as fuse portions 6h. In the current path from the first and second positive terminal groups 40a, 40b to the positive terminal 7, the fuse portion 6h is the portion with the smallest cross-sectional area perpendicular to the current direction. Moreover, when an overcurrent flows between the first and second positive terminal groups 40a, 40b to the positive terminal 7, the fuse portion 6h melts and the current is cut off. That is, the cross-sectional area of ​​the fuse portion 6h is set to a cross-sectional area that melts due to Joule heat when a current (overcurrent) exceeding a given current amount flows.

[0064] In this embodiment, the through-hole 6i is a single hole with a rectangular opening. However, as long as the cross-sectional area of ​​the fuse portion 6h can be set to a predetermined cross-sectional area, the shape and number of the through-hole 6i are not limited. For example, it can also be an oblong shape that is elongated in the width direction of the positive electrode current collector 6b, or multiple holes can be provided. The portion provided with the through-hole 6i is designed to minimize the cross-sectional area of ​​the current path from the first and second positive electrode terminal groups 40a, 40b to the positive terminal 7, while ensuring the strength of the positive electrode current collector 6b, so as to block the flow of current exceeding the set current value.

[0065] The connecting portion 6e connects the first connecting portion 6c and the second connecting portion 6f. In this embodiment, the connecting portion 6e is bent to provide a step between the first and second connecting portions 6c, 6f. However, a step can be omitted. When providing the connecting portion 6e, if its width is narrower than that of the first and second connecting portions 6c, 6f, bending the connecting portion 6e becomes easier.

[0066] [Connection between terminal conductive member and current collector]

[0067] Figure 9 This is a schematic perspective sectional view of the sealing plate 2 with the positive electrode current collector 6b, the fuse insulating member 80 and the external terminal protection insulating member 81 mounted thereon, as viewed from the electrode body side. Figure 9 In the figure, the first and second positive electrode tab groups 40a and 40b are omitted for easier understanding of the drawing.

[0068] The first connecting portion 6c of the positive electrode current collector 6b, to which the first and second positive electrode tab groups 40a and 40b are connected, is disposed on the base portion 11a of the inner insulating member 11 on the positive electrode side. Furthermore, the terminal-side connecting portion 6g on the positive electrode side is disposed on the positive electrode terminal conductive member 6a and then bonded to the positive electrode terminal conductive member 6a. As a bonding method, the two members can be bonded by irradiation with energy beams such as lasers.

[0069] Here, as described above, in this embodiment, the connecting portion 6e is bent to provide a step between the first connecting portion 6c and the second connecting portion 6f. Although the positive terminal conductive member 6a exists directly below the terminal side connecting portion 6g, it does not extend to the position of the fuse portion 6h. Therefore, by connecting the terminal side connecting portion 6g to the positive terminal conductive member 6a, it is possible to Figure 9 As shown, the fuse 6h does not contact the inner insulating member 11, but rather a space 63 is provided between them. Because the fuse 6h does not contact the inner insulating member 11, damage to the inner insulating member 11 due to sparks or heat can be prevented when the fuse 6h is actuated. This prevents electrical reconnection between the sealing plate 2 and the positive electrode current collector 6b.

[0070] In addition, if Figure 6 、 7 As shown, the first connecting portion 8c of the negative electrode current collector 8b, to which the first and second negative electrode terminal groups 50a and 50b are connected, is arranged on the base portion 13a of the internal insulating member 13 on the negative electrode side. The second connecting portion 8f on the negative electrode side is provided with a through-hole 8d having a thin-walled portion at the periphery. The through-hole 8d is engaged with the protrusion 8x provided on the negative electrode terminal conductive member 8a, and the second connecting portion 8f is simultaneously arranged on the negative electrode terminal conductive member 8a. Furthermore, the interlocking portion is joined. As a joining means, the interlocking portion can be joined by irradiation with energy rays such as laser light.

[0071] [Fuse insulation member]

[0072] like Figure 9 As shown, the fuse insulating member 80 comprises a rectangular, flat base portion 80a; a convex portion 80b protruding from the center of the base portion 80a; and fixed claws (not shown) provided at both ends of the base portion 80a in its longitudinal direction. Furthermore, the fuse insulating member 80 is provided so as to span the fuse portion 6h, and the fixed claws are fitted and fixed into through-holes 11e provided in the wall portion 11c, which extends from the rib 11b of the inner insulating member 11.

[0073] The fuse insulating member 80 is made of a material with a melting point of 200°C or higher. Since the melting point remains high even when the fuse is activated, sparks and fuse fragments falling toward the electrode body are reliably prevented. Consequently, internal short circuits caused by sparks and fuse fragments falling toward the electrode body 3 are reliably prevented. Examples of materials for the fuse insulating member 80 include polyimide resins, PFA, and PPS, all of which have a melting point of 200°C or higher.

[0074] In this embodiment, the base portion 80a of the fuse insulating member 80 covers not only the fuse 6h but also the portion of the second connecting portion 6f adjacent to the fuse 6h. This more reliably prevents internal short circuits. However, to prevent internal short circuits, the fuse insulating member 80 only needs to cover at least the entire fuse 6h.

[0075] In addition, the fuse insulating member 80 is as follows in this embodiment: Figure 9 As shown, the structure is as follows: the protruding portion 80b enters the through-hole 6i sandwiched between the fuses 6h, and the base portion 80a contacts and supports the fuse 6h. This structure physically supports the fuse 6h, which has a small cross-sectional area, preventing damage to the fuse 6h due to vibration and the like, and reliably preventing the fuse 6h from moving after it has melted and causing reconnection.

[0076] [External terminal protection insulation member]

[0077] like Figure 9 As shown, the external terminal protection insulating member 81 is disposed between the electrode body 3 and the positive terminal 7 and the positive terminal conductive member 6a, covering the positive terminal 7 and the positive terminal conductive member 6a. Furthermore, similar to the fuse portion insulating member 80, the external terminal protection insulating member 81 is fitted and fixed into another through-hole 11f provided in the wall portion 11c of the internal insulating member 11. In this embodiment, the external terminal protection insulating member 81 and the fuse portion insulating member 80 are adjacent to each other in the longitudinal direction of the positive electrode current collector 6b, and the two are arranged in a substantially flush state. They can be in contact with each other or separated.

[0078] The external terminal protection insulating member 81 prevents the positive electrode terminal 7 from contacting the electrode body 3 and causing a short circuit. In addition, the external terminal protection insulating member 81 is arranged to be separated from the fuse 6h. Therefore, an insulating material with lower heat resistance than the fuse insulating member 80 can be used. For example, a low-cost insulating resin such as PP can be used.

[0079] [Production of Electrode Body]

[0080] The stacking direction surfaces of the first electrode body element 3a and the second electrode body element 3b are directly opposed to each other or opposed to each other through other components. Accordingly, the first and second positive electrode terminal groups 40a, 40b and the first and second negative electrode terminal groups 50a, 50b are bent. Thus, the first electrode body element 3a and the second electrode body element 3b are combined to form a single electrode body 3. An adhesive tape or the like is wrapped around the outer circumference of the combined first and second electrode body elements 3a, 3b to secure the first and second electrode body elements 3a, 3b. Alternatively, the first and second electrode body elements 3a, 3b can be arranged within an electrode body holder 14 formed into a box or bag shape to combine them into one.

[0081] In this embodiment, the electrode body 3, surrounded by an electrode body holder 14 made of a resin sheet molded into a box or bag shape, is inserted into the rectangular outer body 1. A sealing plate 2 is then fitted into the opening of the rectangular outer body 1, and the fitted portion is welded, thereby sealing the opening of the rectangular outer body 1 with the sealing plate 2. Electrolyte is then injected into the rectangular outer body 1 through an electrolyte injection hole 15 provided in the sealing plate 2. The electrolyte injection hole 15 is then sealed with a sealing member 16 such as a blind rivet.

[0082] In the prismatic secondary battery 20 according to the above-described embodiment, first and second positive electrode terminal groups 40a and 40b and first and second negative electrode terminal groups 50a and 50b are respectively arranged at the end of the electrode body 3 on the sealing plate 2 side. Furthermore, the positive electrode terminal group is connected to the surface of the positive electrode current collector 6b arranged along the sealing plate 2 on the electrode body 3 side in a bent state. Furthermore, the negative electrode terminal group is connected to the surface of the negative electrode current collector 8b arranged along the sealing plate 2 on the electrode body 3 side in a bent state. This structure results in a secondary battery with a higher volume energy density.

[0083] (Implementation Method 2)

[0084] The second embodiment differs from the first embodiment in the structure from the second connection portion of the positive electrode current collector to the positive electrode terminal in the current path from the electrode assembly to the positive electrode terminal. Therefore, the following mainly describes the differences from the first embodiment.

[0085] In this embodiment, if Figure 10 As shown, a fusible portion 106h comprising a thin, annular portion is formed on the second connecting portion 106f of the positive current collector. This fusible portion 106h is composed of a thin portion that is thinner than the rest of the positive current collector. Furthermore, a cylindrical protrusion is formed on the positive terminal conductive member 106a, which is electrically connected to the positive terminal 107, and the fusible portion 106h is welded to this protrusion. Due to this structure, the fusible portion 106h also serves as the terminal-side connecting portion.

[0086] A fuse insulating member 180 is disposed on the electrode body (not shown) side (lower side of the figure) of the fuse 106f. As in the first embodiment, the fuse insulating member 180 is made of a material with a melting point of 200°C or higher and is fitted and fixed to a through-hole (not shown) provided in the wall portion (not shown) of the inner insulating member 111. A protrusion is provided in the center portion of the fuse insulating member 180, which contacts a portion of the fuse 106f, thereby supporting the fuse 106f. Therefore, as in the first embodiment, even if the fuse is activated, the high melting point of the fuse insulating member 180 reliably prevents sparks and fuse fragments from falling onto the electrode body. Furthermore, since the fuse insulating member 180 physically supports the fuse 106h, damage to the fuse 106h due to vibration, etc., is prevented, and reconnection caused by movement of the fuse 106h after it has melted, is reliably prevented.

[0087] In this embodiment, the first connection portion 106c of the positive electrode current collector is located further inward than the positive electrode terminal 107 in the longitudinal direction of the sealing plate 102, as in the first embodiment, and is connected to the second connection portion 106f via the connecting portion 106e. However, unlike the first embodiment, the fuse portion 106f is located further outward than the positive electrode terminal 107 in the longitudinal direction of the sealing plate 102. Furthermore, as in the first embodiment, an external insulating member 110 is disposed between the positive electrode terminal 107 and the sealing plate 102 to electrically insulate the two.

[0088] With this structure, in this embodiment, the end of the first connecting portion 106c of the positive electrode current collector can be extended to the vicinity of the positive electrode terminal 107. This increases the width of the positive electrode tab group connected to the first connecting portion 106c. As a result, a high-output secondary battery can be realized.

[0089] (Other embodiments)

[0090] The above-mentioned embodiments are illustrative of the present disclosure. The present disclosure is not limited to these examples. Known technologies, conventional technologies, and common knowledge may be combined with these examples, or a portion thereof may be replaced. In addition, any modifications that can be easily conceived by a person skilled in the art are also included in the present disclosure.

[0091] In the above embodiment, the electrode body 3 is shown to include two electrode body elements, but the present invention is not limited thereto. The electrode body 3 may also include three or more electrode body elements. The electrode body elements are not limited to stacked electrode bodies, but may also be wound types in which a strip-shaped positive electrode plate and a strip-shaped negative electrode plate are wound with a strip-shaped separator. In addition, an electrode body including one electrode body element may also be a wound type electrode body in which a strip-shaped positive electrode plate and a strip-shaped negative electrode plate are wound with a strip-shaped separator.

[0092] The external insulating members on the positive and negative electrode sides, the internal insulating members on the positive and negative electrode sides, and the external terminal protection insulating members can be made of insulating materials, preferably resins, such as polypropylene (PP), polyethylene (PE), or polyphenylene sulfide (PPS).

[0093] As energy rays used for welding (joining), laser beams, electron beams, and the like can be used.

[0094] For the positive electrode plate, negative electrode plate, separator, electrolyte, etc., known materials can be used. The battery system of the secondary battery of the present invention is not limited. For example, it can be a non-aqueous electrolyte secondary battery such as a lithium ion battery. In addition, the shape of the secondary battery of the present disclosure is not limited to a specific shape.

[0095] Alternatively, a connecting member may be used that connects both the fuse insulating member and the sealing plate-current collector insulating member, thereby indirectly supporting the fuse insulating member via the sealing plate-current collector insulating member.

[0096] It does not matter if a tab conductive member is disposed between the tab and the first connecting portion.

[0097] The fuse part is the part with the smallest cross-sectional area perpendicular to the current direction in the current path from the connector to the external terminal. The means for minimizing the cross-sectional area are not limited to setting a through hole or reducing the thickness. It is also possible to change the material, reduce the width, or combine these means. Various methods can be used.

[0098] -Explanation of Symbols-

[0099] 1 Square outer body

[0100] 2 Sealing plate

[0101] 3 Electrode body

[0102] 3a First electrode element

[0103] 3b Second electrode element

[0104] 4 positive plates

[0105] 4a Positive electrode core

[0106] 4b Positive electrode active material mixture layer

[0107] 4d positive electrode protection layer

[0108] 40 Positive terminal

[0109] 40a, 40b positive terminal group

[0110] 5 Negative plate

[0111] 5a Negative electrode core

[0112] 5b Negative electrode active material mixture layer

[0113] 50 Negative terminal

[0114] 50a, 50b negative terminal group

[0115] 6a Positive terminal conductive member

[0116] 6b Positive electrode current collector

[0117] 6c First connection part

[0118] 6d opening

[0119] 6e Connection

[0120] 6f Second connection

[0121] 6g Terminal side connection part

[0122] 6h fuse

[0123] 6i Through hole

[0124] 7 Positive terminal

[0125] 8a Negative terminal conductive member

[0126] 8b Negative electrode current collector

[0127] 8c First connection part

[0128] 8d through hole

[0129] 8f Second connection

[0130] 9 Negative terminal

[0131] 10 External insulation member

[0132] 11 Internal insulation member

[0133] 11a Base

[0134] 11b Rib

[0135] 11c Wall

[0136] 11d Opening

[0137] 11e through hole

[0138] 11f Through hole

[0139] 12 External insulation member

[0140] 13 Internal insulation member

[0141] 13a Base

[0142] 13b Rib

[0143] 14 Electrode body bracket

[0144] 15 Electrolyte filling hole

[0145] 16 Sealing member

[0146] 17 Gas exhaust valve

[0147] 20 square secondary batteries

[0148] 60, 61 welding part

[0149] 80 Fuse insulation component

[0150] 81 External terminal protection insulation member

[0151] 100 battery housing

[0152] 102 sealing plate

[0153] 106a Positive terminal conductive member

[0154] 106c First connecting portion

[0155] 106e Connection

[0156] 106f Second connecting portion

[0157] 106h Fuse

[0158] 107 Positive terminal

[0159] 110 External insulation member

[0160] 111 Internal insulation member

[0161] 180 Fuse insulating component.

Claims

1. A secondary battery comprising: An electrode body, wherein the positive electrode plate and the negative electrode plate are stacked with a separator therebetween; an outer casing having an opening and accommodating the electrode body; A sealing plate for sealing the opening; as well as External terminals are mounted on the sealing plate. A tab 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 current collector comprises: a first connection portion to which the contact or a contact conductive member connected to the contact is connected; and a second connection portion having a fuse portion. The fuse portion is a portion that is melted when an overcurrent flows in the current path by minimizing the cross-sectional area perpendicular to the current direction in the current path from the contact to the external terminal. The portion of the fuse portion facing the electrode body is covered by a fuse portion insulating member. The fuse insulating member is a member made of a material having a melting point of 200°C or more. The current collector includes a connecting portion connecting the first connecting portion and the second connecting portion, the connecting portion is bent, and a step is provided between the first connecting portion and the second connecting portion. The second connection portion has a terminal-side connection portion connected to a terminal conductive member, and the terminal conductive member is connected to the external terminal. The terminal conductive member exists just below the terminal-side connecting portion and does not extend to the position of the fuse portion. A sealing plate-current collector insulating member is disposed between the sealing plate and the current collector. A space is provided between the fuse portion and the sealing plate-current collector insulating member.

2. The secondary battery according to claim 1, wherein The fuse-part insulating member supports the fuse part while being in contact with the fuse part.

3. The secondary battery according to claim 1, wherein The fuse portion insulating member also covers a portion of the second connection portion that is adjacent to the fuse portion.

4. The secondary battery according to claim 1, wherein The fuse portion insulating member is supported by the sealing plate-current collector insulating member.

5. The secondary battery according to claim 1, wherein An external terminal protection insulating member is disposed between the electrode body and the external terminal on the side of the external terminal facing the electrode body. A sealing plate-current collector insulating member is disposed between the sealing plate and the current collector. The external terminal protection insulating member is supported by the sealing plate-current collector insulating member.

6. The secondary battery according to any one of claims 1 to 5, wherein The outer body is square in shape, The external terminal is a positive external terminal, The first connection portion is located further inward than the second connection portion in the long side direction of the sealing plate, The fuse portion is located outside the positive electrode external terminal in the longitudinal direction of the sealing plate. The terminal-side connecting portion is constituted by the fuse portion.

Images