WO2014141554A1

WO2014141554A1 - Secondary battery

Info

Publication number: WO2014141554A1
Application number: PCT/JP2013/083311
Authority: WO
Inventors: 西村　拓也; 雄輔内田; 貴紀梶本; 佳樹宮本; 田中　明
Original assignee: 新神戸電機株式会社
Priority date: 2013-03-15
Filing date: 2013-12-12
Publication date: 2014-09-18
Also published as: JP6015845B2; JPWO2014141554A1

Abstract

The present invention improves secondary battery safety and reliability whilst maintaining a sufficiently large current value during charging and discharging. The secondary battery of the present invention is provided with an electrode terminal (4), an electrode plate, current-collector plates (13) that are connected to the electrode plate, and pressing plates (15) that sandwich the current-collector plates (13) to attach to the electrode terminal (4). A through-bolt (18), which passes through a through hole (161), a through hole (162), and a through hole (16), is fastened with a nut (20), and a screw bolt (19), which passes through a through hole (171) and a through hole (172), is fastened with a screw hole (17) such that the pressing plates (15) sandwich the current-collector plates (13) and are attached to the electrode terminal (4), and the current-collector plates (13) are connected to the electrode terminal (4).

Description

Secondary battery

The present invention relates to a secondary battery such as a lithium ion battery.

In recent years, secondary batteries have been used in various fields, for example, as power sources for electronic devices such as mobile phones. Most of the secondary batteries used for these applications are small-sized, high capacity, and high energy density lithium ion batteries. In recent years, lithium ion batteries have also been used as power sources for electric vehicles, power sources for power storage in homes, etc., or emergency power sources.

As this emergency power supply, a power supply system including a lead battery as a secondary battery, that is, a lead storage battery has been conventionally used. The lead battery is superior in that the cost per electric energy is lower than that of the lithium ion battery and the safety when the secondary battery is overcharged is high.

On the other hand, lithium ion batteries are excellent in that they have high energy density and high input / output characteristics. The volume energy density of the lithium ion battery is about twice the volume energy density of the lead battery, and the weight energy density of the lithium ion battery is at least three times the weight energy density of the lead battery. For this reason, in a power supply system composed of lead batteries, a large number of lead batteries must be connected in series to increase the voltage, and a large number of lead batteries are connected in parallel to increase the current. There must be. Therefore, the power supply system composed of lead batteries has a problem of installation space in which the area of the part where the lead batteries are to be installed must be increased. Due to such a problem of installation space, for example, it has been difficult to install a power supply system composed of a lead battery for use as a backup power supply in an urban area.

On the other hand, a large-capacity power supply system composed of lithium ion batteries is expected as a power supply system for backup power supply in the above-mentioned city center. Further, if the output characteristics per lithium ion battery can be increased, a power supply system including a smaller number of lithium ion batteries can be constructed. As a result, the overall cost can be reduced, and the superiority over lead batteries can be further improved. In this case, development of a lithium ion battery having high energy density, high input / output characteristics, high safety and high reliability is required.

For example, when discharging with a large current, that is, so-called high-rate discharge using a lithium ion battery, there is a problem that Joule heat becomes so large that it cannot be ignored at a portion where the electrode plate and the electrode terminal are connected. When the lithium ion battery is exposed to a high temperature by this Joule heat, the active material applied to the electrode plate may be deteriorated, and the life of the lithium ion battery may be shortened. In order to solve such a problem, for example, it is desirable to reduce the contact resistance between the electrode plate and the electrode terminal.

Japanese Patent Laid-Open No. 50-134147 describes a method of collecting current collecting tabs into a single current collecting plate and connecting the current collecting plate to a pole column. In Patent Document 2 (Japanese Patent No. 3428336), the area of the joint surface between the electrode plate group and the pole column is defined, and the connection method is any one of welding, screw tightening, and pressure bonding. A technique for reducing the contact resistance between the electrode and the pole is described. Patent Document 3 (Japanese Patent No. 4494731) describes a method of fixing a current collecting tab to a pole column with a screw and welding the screw and the pole column.

In Patent Document 4 (Japanese Patent Application Laid-Open No. 2005-5215), a positive electrode plate and a negative electrode plate are divided into a plurality of sets for each predetermined number of sheets, a tab and a current collecting lead for each predetermined number are joined, and then the electrode group is connected to a battery can. The other end of the current collecting lead is fixed to the positive electrode terminal and the negative electrode terminal with a bolt, and the current collecting lead and the terminal are joined by welding to produce a lithium ion battery. Further, Patent Document 5 (Japanese Patent Application Laid-Open No. 2010-205546) discloses a non-aqueous electrolyte in which lithium hexafluorophosphate of a lithium salt is dissolved in an organic solvent as a non-aqueous electrolyte for a lithium ion battery. A technique for injecting liquid into a battery can is described.

JP 50-134147 A Japanese Patent No. 3428336 Japanese Patent No. 4494731 Japanese Patent Laying-Open No. 2005-5215 JP 2010-205546 A

An object of the present invention is to provide a secondary battery having both high safety and high reliability.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

A secondary battery according to a representative embodiment includes a battery container, a first electrode terminal provided in the battery container and having a first polarity, and a second polarity provided in the battery container and opposite to the first polarity. A second electrode terminal. The secondary battery is provided in the battery container and has a plurality of first electrode plates each having a first polarity, and a plurality of secondary electrodes respectively provided in the battery container and each having a second polarity. A second electrode plate. Further, the secondary battery includes a first current collector plate connected to each of the plurality of first electrode plates, a first attachment plate attached to the first electrode terminal across the first current collector plate, A first screw member, a first nut member, and a second screw member, each having a first mounting plate attached to one electrode terminal. Each of the plurality of first electrode plates and each of the plurality of second electrode plates are alternately stacked via separators. The first electrode terminal is formed with a first through hole for allowing the first screw member to pass therethrough and a first screw hole for fastening the second screw member. The first mounting plate is formed with a first screw hole for penetrating the first screw member and a second screw hole for penetrating the second screw member. The first current collector plate is formed with a third screw hole for allowing the first screw member to pass therethrough and a fourth screw hole for allowing the second screw member to pass therethrough. The 1st screw member which penetrated the 1st screw hole, the 3rd screw hole, and the 1st penetration hole is fastened with the 1st nut member, and the 2nd screw hole and the 4th screw hole When the second screw member penetrating through the first screw hole is fastened to the first screw hole, the first mounting plate is attached to the first electrode terminal with the first current collecting plate interposed therebetween, and the first current collecting plate is the first current collecting plate. Connected to electrode terminals.

The secondary battery may include a third screw member and a second nut member that attach the first mounting plate to the first electrode terminal. The first electrode terminal is formed with a second through hole for allowing the third screw member to pass therethrough, and the first mounting plate is formed with a fifth screw hole for allowing the third screw member to pass therethrough. The first current collector plate may be formed with a sixth screw hole for allowing the third screw member to pass therethrough. At this time, the third screw member penetrating the fifth screw hole, the sixth screw hole, and the second through hole is fastened to the second nut member, thereby sandwiching the first current collector plate. A first mounting plate is attached to the first electrode terminal, and the first current collector plate is connected to the first electrode terminal.

In the above secondary battery, the first screw hole may be formed at the center of the first end face of the first electrode terminal. The first through hole is formed in a first portion of the first end face located on the first side of the center part, and the second through hole is a first side of the center part of the first end face. It may be formed in the second portion located on the opposite side.

In the secondary battery, the first screw hole may be formed at the center of gravity of the first end surface of the first electrode terminal. The first through hole is formed at a first position away from the center of gravity of the first end surface within the first end surface, and the second through hole is located at the first position around the center of gravity within the first end surface. You may form in the 2nd position which is a symmetrical position.

In the above secondary battery, the first through hole may be formed in a first portion of the first end face of the first electrode terminal located on the first side of the center portion of the first end face. Moreover, the 1st screw hole may be formed in the 2nd part located in the opposite side to the 1st side of a center part among 1st end surfaces.

In the above secondary battery, the first through hole may be formed at a first position away from the center of gravity of the first end surface within the first end surface of the first electrode terminal. The first screw hole may be formed in a second position that is symmetrical to the first position with the center of gravity as the center in the first end face.

In the above secondary battery, the first nut member may be a double nut.

The secondary battery may have a plurality of first current collecting tabs provided at respective end portions of the plurality of first electrode plates. In addition, the first current collecting plate may be connected to each of the plurality of first current collecting tabs.

The secondary battery includes a second current collector plate connected to each of the plurality of second electrode plates, a second attachment plate attached to the second electrode terminal across the second current collector plate, and a second electrode You may have the 4th screw member, the 3rd nut member, and the 5th screw member which have attached the 2nd attachment board to the terminal. At this time, the second electrode terminal is formed with a third through hole for allowing the fourth screw member to pass therethrough and a second screw hole for fastening the fifth screw member. The second mounting plate is formed with a seventh screw hole for allowing the fourth screw member to pass therethrough and an eighth screw hole for allowing the fifth screw member to pass therethrough. The second current collector plate is formed with a ninth screw hole for allowing the fourth screw member to pass therethrough and a tenth screw hole for allowing the fifth screw member to pass therethrough. The fourth screw member that penetrates the seventh screw hole, the ninth screw hole, and the third through hole is fastened to the third nut member, and the eighth screw hole and the tenth screw. When the fifth screw member penetrating the working hole is fastened to the second screw hole, the second mounting plate is attached to the second electrode terminal across the second current collecting plate, and the second current collecting plate is The second electrode terminal is connected.

The secondary battery according to the representative embodiment is housed in a battery can, and an electrode group in which each of a plurality of positive plates and each of a plurality of negative plates are alternately stacked in a first direction via a separator. 3 or more. The three or more electrode groups include two or more electrode groups (A) and one or more electrode groups (B), and are arranged in the first direction. Negative electrode plates are respectively disposed on both end surfaces in the first direction of the electrode group (A), and positive electrode plates are respectively disposed on both end surfaces in the first direction of the electrode group (B). Electrode groups (A) are respectively arranged at positions on both ends of the array of electrode groups. Only one electrode group (B) is arranged at positions other than both ends of the electrode group arrangement, or two or more electrode groups (B) so that the electrode groups (B) are not adjacent to each other. And one or more electrode groups (A) are arranged.

The secondary battery according to the representative embodiment is housed in a battery can, and an electrode group in which each of a plurality of positive plates and each of a plurality of negative plates are alternately stacked in a first direction via a separator. There are multiple. The plurality of electrode groups are arranged in the first direction. Negative electrode plates are respectively disposed on both end faces of each of the plurality of electrode groups in the first direction.

A positive and negative electrode plate laminated via a separator has an electrode tab at each end, and an electrode group in which a predetermined plurality of positive and negative electrode plates are alternately laminated via a separator includes a plurality of the electrode groups. The electrode group is an electrode group (A) in which the electrode plates located on both end surfaces of the electrode group in the stacking direction are both negative electrode plates and the electrode group in the stacking direction of the electrode group. An electrode group (C) in which the electrode plate located on one end face is a positive electrode plate and the electrode plate located on the other end face is a negative electrode plate. In the electrode group (C), the negative electrode plate side of the stacking direction end face is the inner wall surface of the battery can The electrode group (C) or the electrode group (A) is arranged so that the opposing surfaces of the adjacent electrode groups do not become a positive electrode plate except for a position opposite to the inner wall surface of the battery can. A configuration in which the electrode group (C) is arranged can be employed.

Using any one of the above three types of electrode group configuration, for each electrode group, the same polarity electrode tab is joined to each positive and negative current collector plate, and the same polarity said current collector plate together with the holding plate is positive and negative by a bolt. It may be fastened to the terminal base part.

Using any one of the above three electrode group configurations, the electrode tabs of the same polarity of each electrode group may be joined to the positive and negative terminal base portions by friction stir welding.

The secondary battery may be configured with a total of 400 positive and negative electrode plates.

A secondary battery comprising: an electrode group in which a plurality of positive and negative electrode plates are laminated via a separator; a plurality of electrode tabs extending from the electrode group; and a terminal communicating inside and outside the battery can, wherein the electrode The group is a group (A) in which one end face and the other end face in the electrode group stacking direction are formed of negative electrode plates. As an example, when four electrode groups are produced using 200 positive electrode plates and 204 negative electrode plates, one electrode group is composed of 50 positive electrode plates and 51 negative electrode plates. When the positive electrode plate and the negative electrode plate are alternately arranged via the separator, the negative electrode plate exists at both ends of the electrode group. In addition, from the viewpoint of the electrode group configuration, the configuration shown in the following second embodiment is also conceivable.

Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

According to the present invention, it is possible to provide a secondary battery having both high safety and high reliability.

1 is a partially broken perspective view showing a secondary battery according to Embodiment 1. FIG. 3 is a cross-sectional view of the secondary battery according to Embodiment 1. FIG. 3 is a cross-sectional view of the secondary battery according to Embodiment 1. FIG. It is a figure which shows the structure of a small electrode bundle. It is a figure which shows the structure of an electrode bundle. It is a figure which shows the structure of a small electrode group. It is a disassembled perspective view which shows an electrode terminal, a current collection board, and a pressing board. It is a disassembled perspective view which shows an electrode terminal, a current collection board, and a pressing board. It is sectional drawing which shows the various examples of the connection structure of a current collecting plate. It is sectional drawing which shows the various examples of the connection structure of a current collecting plate. It is sectional drawing which shows the various examples of the connection structure of a current collecting plate. It is sectional drawing which shows the various examples of the connection structure of a current collecting plate. It is sectional drawing which shows the various examples of the connection structure of a current collecting plate. It is sectional drawing which shows the various examples of the connection structure of a current collecting plate. It is a disassembled perspective view which shows an electrode terminal, a current collection board, and a pressing board. It is a graph which shows the result of having measured the resistance between a current collection board and an electrode terminal about the secondary battery of Example 1 and Comparative Example 1. FIG. It is a graph which shows the result of having measured the temperature of the electrode terminal at the time of discharging. It is a perspective view of a battery can. It is sectional drawing of a lithium ion battery at the time of using the connection method by a volt | bolt nut. It is sectional drawing perpendicular | vertical to the lamination direction of the positive electrode plate and negative electrode plate of a lithium ion battery. It is a perspective view of the electric power generation element of the state which removed the battery can. It is a perspective view of a lithium ion battery in the state where a battery can was removed. It is a disassembled perspective view which shows the connection method by a volt | bolt nut. It is a figure which shows the connection method by a volt | bolt nut. It is a figure which shows the joining method by friction stirring. FIG. 10 is an explanatory diagram of Example 5. FIG. 10 is an explanatory diagram of Example 6. FIG. 10 is an explanatory diagram of Example 7.

Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be appropriately implemented without departing from the scope of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, when ranges are shown as A to B, A or more and B or less are shown unless otherwise specified.

(Embodiment 1)
First, the secondary battery of Embodiment 1 will be described. The first embodiment is an embodiment when the present invention is applied to a prismatic lithium ion battery as a secondary battery.

In Patent Documents 1 to 3 described above, for example, charging / discharging under the condition that the charging / discharging time rate is about 1 C and the charging / discharging current is about 100 Ah is assumed. On the other hand, charging / discharging under conditions where the charging / discharging time rate and charging / discharging current are 5 times this, that is, charging / discharging time rate is about 5 C and charging / discharging current is about 500 Ah, This is called high current discharge. When performing such high-rate charging / discharging or large-current charging / discharging, in the lithium ion battery in which the electrode plate and the electrode terminal are connected by the connection method described in Patent Documents 1 to 3, the amount of heat generated by Joule heat Therefore, the safety and life of the lithium ion battery cannot be improved.

Also, when the electrode plate and electrode terminal are connected by welding, the metal atoms are tied together, so the contact resistance between the electrode plate and electrode terminal is different from the case of mechanical connection by caulking or screwing. Can be greatly reduced. However, when processing is performed by welding, sparks are generated, and there is a risk that foreign substances made of metal are generated. Then, the generated spark may damage the separator, or a foreign material made of the generated metal may be mixed between the electrode plates to cause a short circuit.

In order to prevent the occurrence of such a short circuit, for example, as described in Patent Document 3, the distance between the electrode plate and the welded portion of the current collecting tab is increased by elongating the current collecting tab. It is possible to make it longer. Alternatively, welding may be performed in a state where a jig for preventing the generated spark from reaching the electrode plate is mounted across the current collecting tab. However, when the distance between the electrode plate and the portion where the current collecting tab is welded is increased, the contact resistance between the electrode plate and the electrode terminal may increase, which is disadvantageous in performing high-rate charge / discharge. It is. Moreover, when welding is performed in a state where a jig is attached across the electrode tabs, a large number of current collecting tabs may be collectively damaged.

In the first embodiment, an electrode plate is connected to an electrode terminal by a simple connection method that does not use welding, can withstand charge / discharge at a large current, and has a high safety and high reliability. The issue is to provide.

<Battery>
First, the battery case will be described. FIG. 1 is a partially broken perspective view showing the secondary battery of the first embodiment. In FIG. 1, as an example, each of two directions orthogonal to each other in the horizontal plane is defined as an X-axis direction and a Z-axis direction, respectively, and is orthogonal to the horizontal plane, that is, the X-axis direction and the Z-axis direction. The vertical direction, which is the direction in which the image is generated, is the Y axis direction.

As shown in FIG. 1, the secondary battery of the first embodiment has a battery case 1 that is a battery container. The battery case 1 has a prismatic shape with an open surface, and includes a lid 1 a that closes the opening of the battery case 1. After the electrode group is inserted into the battery case 1, the battery case 1 is sealed by welding the opening peripheral portion of the battery case 1 and the lid 1 a. That is, the lid 1a keeps the inside of the battery case 1 in a sealed state. From the viewpoint of mechanical strength, the battery case 1 is preferably made of various metal materials such as stainless steel or an aluminum-based material containing aluminum as a main component. The battery case 1 is provided with a liquid injection port 2 and a gas release valve 3. The liquid injection port 2 is for injecting an electrolytic solution (not shown) into the battery case 1. The gas release valve 3 is for releasing the internal gas when the temperature of the secondary battery rises due to an internal short circuit or the like and the internal pressure in the battery case 1 rises above a predetermined pressure.

The battery case 1 is also referred to as a battery can (see Embodiment 2 described later).

From the injection port 2, lithium hexafluorophosphate (LiPF ₆ ) is added to a solution obtained by mixing one or more cyclic carbonate organic solvents such as ethylene carbonate and chain carbonate organic solvents such as dimethyl carbonate. Then, a nonaqueous electrolytic solution in which a lithium salt such as lithium tetrafluoroborate (LiBF ₄ ) is dissolved is injected. After injecting the non-aqueous electrolyte, the liquid injection port 2 is sealed with a liquid port stopper.

The secondary battery of the first embodiment has two electrode terminals 4. One of the two electrode terminals 4 is an electrode terminal having a first polarity, and the other is an electrode terminal having a second polarity opposite to the first polarity. Therefore, one of the two electrode terminals 4 is the positive electrode terminal 4a, and the other is the negative electrode terminal 4b. The electrode terminal 4 is provided in the battery case 1 so as to penetrate the lid 1a of the battery case 1, and communicates, that is, electrically connects the inside and the outside of the secondary battery. The positive electrode terminal 4a is made of, for example, a material containing aluminum as a main component, that is, an aluminum-based material. The negative electrode terminal 4b is made of, for example, a material containing copper as a main component, that is, a copper-based material, or made of a material containing nickel as a main component, that is, a nickel-based material.

<Electrode group>
Next, the electrode group will be described. 2 and 3 are cross-sectional views of the secondary battery of the first embodiment. 2 shows a case where the secondary battery is viewed from the X-axis direction of FIG. 1, and FIG. 3 shows a case where the secondary battery is viewed from the Z-axis direction of FIG.

As shown in FIG. 1 to FIG. 3, the secondary battery of the first embodiment has a plurality of electrode plates 6. Among the plurality of electrode plates 6, some of the plurality of electrode plates are electrode plates having a first polarity, and the other plurality of electrode plates are electrode plates having a second polarity opposite to the first polarity. . Accordingly, among the plurality of electrode plates 6, some of the plurality of electrode plates 6 are positive electrode plates 6a, and the other plurality of electrode plates 6 are negative electrode plates 6b. Each of the plurality of positive electrode plates 6 a and each of the plurality of negative electrode plates 6 b are alternately stacked in the Z-axis direction via the separator 8 to constitute an electrode group 9. That is, the electrode group 9 includes a plurality of positive electrode plates 6a and a plurality of negative electrode plates 6b, and each of the plurality of positive electrode plates 6a and each of the plurality of negative electrode plates 6b passes through the separator 8 in the Z-axis direction. They are stacked alternately.

In addition, the electrode group 9 is also referred to as a power generation element (see Embodiment 2 described later).

The positive electrode plate 6a includes a positive electrode current collector made of an aluminum foil formed in a plate shape, and a mixture layer provided on both surfaces of the positive electrode current collector and including a positive electrode active material, a binder, and a conductive agent. is doing.

As the positive electrode active material, 1) one represented by the chemical formula LiMO ₂ (M is at least one transition metal) or 2) spinel manganese can be used. Alternatively, as a positive electrode active material, 3) a material obtained by substituting a part of Mn, Ni, Co or the like with one or more transition metal elements among materials such as lithium manganate, lithium nickelate or lithium cobaltate Can be used. Furthermore, as the positive electrode active material, a material obtained by substituting a part of the transition metal with a metal element such as Mg or Al among the materials described in 3) can be used. In addition, as a positive electrode active material, a phosphate compound, LiFePO ₄ , LiMnPO ₄ , LiMn _X M _1-X PO ₄ (0.3 ≦ x ≦ 1, M is Li, Fe, Ni, Co, Ti, One or more elements selected from Cu, Zn, Mg and Zr) can be used.

As the conductive agent, a known conductive agent can be used. For example, a carbon-based conductive agent such as graphite, acetylene black, carbon black, or carbon fiber can be used. However, materials used as the conductive agent are not limited to these materials.

As a binder, that is, a binder, a known binder can be used. For example, polyvinylidene fluoride, styrene / butadiene rubber, isoprene rubber, or the like can be used. However, materials used as the binder are not limited to these materials.

In the first embodiment, in Examples 1 to 4 to be described later, a metal oxide lithium manganate is used as the positive electrode active material, and polyvinylidene fluoride (hereinafter referred to as PVDF) is used as the binder. As the agent, acetylene black is used.

The negative electrode plate 6b is formed in a plate shape, and is provided on both surfaces of a material having high conductivity and flexibility, for example, a negative electrode current collector made of copper or nickel, and a negative electrode current collector, and a negative electrode active material and a binder. And a mixture layer containing a conductive agent.

As a negative electrode active material, 1) a carbon-based material such as graphite or amorphous carbon, 2) an oxide-based material such as Li ₄ Ti ₅ O ₁₂ 3) a metal-based material or alloy-based material such as tin or silicon Can be used.

In Embodiment 1, in Examples 1 to 4 described later, graphite is used as the negative electrode active material, PVDF is used as the binder, and acetylene black is used as the conductive agent.

The separator 8 is formed in a sheet shape from a porous material such as polyolefin or non-woven fabric through which lithium ions can pass. Examples of the polyolefin material include polypropylene or polyethylene, and examples of the nonwoven material include glass or paper. The separator 8 has a size that can prevent the positive electrode plate 6a and the negative electrode plate 6b from contacting each other in a stacked state.

The secondary battery of the first embodiment has a plurality of current collecting tabs 10. Each of the plurality of current collecting tabs 10 is provided at each end of each of the plurality of electrode plates 6. Among the plurality of current collecting tabs 10, some of the plurality of current collecting tabs 10 are current collecting tabs 10 having a first polarity, and the other plurality of current collecting tabs 10 are second opposite to the first polarity. It is the current collection tab 10 which has polarity. Accordingly, among the plurality of current collecting tabs 10, some of the current collecting tabs 10 are positive current collecting tabs 10a, and the other plurality of current collecting tabs 10 are negative current collecting tabs 10b. That is, the secondary battery according to the first embodiment has a plurality of current collecting tabs 10a provided at the respective end portions of the plurality of positive electrode plates 6a. In addition, the secondary battery according to the first embodiment includes a plurality of current collecting tabs 10b provided at the respective end portions of the plurality of negative electrode plates 6b.

Note that the current collecting tab is also referred to as an electrode tab (see Embodiment 2 described later).

FIG. 4 is a diagram showing the configuration of the electrode bundle, FIG. 5 is a diagram showing the configuration of the electrode bundle, and FIG. 6 is a diagram showing the configuration of the small electrode group.

As shown in FIG. 4, a laminate in which the negative electrode plate 6b, the separator 8, the positive electrode plate 6a, and the separator 8 are laminated in this order in the Z-axis direction can be used as a minimum unit laminate. The laminate is referred to as a small electrode bundle 11. The small electrode bundle 11 includes a current collecting tab 10a provided at the end of the positive electrode plate 6a and a current collecting tab 10b provided at the end of the negative electrode plate 6b.

As shown in FIG. 5, an array in which a plurality of electrode bundles 11 are arranged in the Z-axis direction, that is, an assembly in which the plurality of electrode bundles 11 are bundled in the Z-axis direction is referred to as an electrode bundle 12.

The secondary battery of the first embodiment has two current collecting plates 13 for each electrode bundle 12. A plurality of current collecting tabs 10 provided at respective end portions of the plurality of electrode plates 6 are connected to the current collecting plate 13 collectively.

One of the two current collector plates 13 is a current collector plate having a first polarity, and the other is a current collector plate having a second polarity opposite to the first polarity. Therefore, one of the two current collecting plates 13 is a positive current collecting plate 13a, and the other is a negative current collecting plate 13b. That is, a plurality of current collecting tabs 10 a provided respectively at end portions of the plurality of positive electrode plates 6 a included in the electrode bundle 12 are connected to the current collecting plate 13 a together. In addition, a plurality of current collecting tabs 10 b provided at the respective end portions of the plurality of negative electrode plates 6 b included in the electrode bundle 12 are collectively connected to the current collecting plate 13 b.

The connection method between the current collecting tab 10 and the current collecting plate 13 is not particularly limited. Therefore, the current collecting tab 10 and the current collecting plate 13 are connected so that, for example, the connection resistance between the current collecting tab 10 and the current collecting plate 13 is small and no spark or metal powder is generated at the time of connection. Connected by way. Alternatively, the current collecting tab 10 and the current collecting plate 13 are connected even if, for example, the connection resistance between the current collecting tab 10 and the current collecting plate 13 is reduced and sparks or metal powder is generated during the connection. It is connected by the joining method devised so that a spark or metal powder may not scatter around the part to be done. Specifically, the plurality of current collecting tabs 10 and the current collecting plate 13 are connected by ultrasonic welding, laser welding, or the like. In addition, as shown in FIG. 6, the part where the some current collection tab 10 and the current collecting plate 13 are joined is called junction part BD.

As shown in FIG. 6, an assembly composed of one electrode bundle 12 and two current collector plates 13, that is,

current collector plates

13 a and 13 b is referred to as a small electrode group 14. An array in which a plurality of small electrode groups 14 are arranged in the Z-axis direction, that is, an assembly in which the plurality of small electrode groups 14 are bundled in the Z-axis direction is the electrode group 9 described above.

In FIG. 5, an electrode bundle 12 including three electrode bundles 11 is illustrated as an example, but FIG. 2 illustrates an electrode bundle 12 including four electrode bundles 11 as another example. . In FIG. 2, as an example, an electrode group 9 including two small electrode groups 14 is illustrated.

As shown in FIG. 2, it is preferable that the negative electrode plates 6b are disposed on both end faces in the Z direction of the electrode group 9, respectively. That is, it is preferable that the negative electrode plate 6b is disposed on the end surface of the electrode group 9 that faces the inner wall of the battery case 1, and the inner wall of the battery case 1 and the negative electrode plate 6b face each other. Thereby, compared with the negative electrode plate 6b, since the positive electrode plate 6a which is in contact with other members and easily short-circuits does not face the inner wall of the battery case 1, the positive electrode plate 6a and the inner wall of the battery case 1 are in contact and short-circuited. This can be prevented.

<Connecting structure of current collector plate>
Next, the connection structure of the current collector plate will be described. Here, three holes are formed in the current collector plate, and the current collector plate is formed by two through bolts and one screw bolt, or by one through bolt and two screw bolts. The case where it is connected to the electrode terminal will be described as an example.

In the present specification, each of the through bolt and the screw bolt is a bolt member. However, since the bolt is a kind of screw, each of the through bolt and the screw bolt is also a screw member. As will be described later with reference to FIG. 11, the through bolt has a relatively large length, that is, is long, and has a screw thread or a thread groove formed on the outer peripheral surface of the shaft portion. It is a screw member also called a screw. On the other hand, the screw bolt is a screw member that is also referred to as a small screw or a short screw because its length is relatively small, that is, short, and a screw thread or a screw groove is formed on the outer peripheral surface of the shaft portion.

In the specification of the present application, the current collector plate is connected to the electrode terminal by two through bolts and one screwed bolt, which means that two through holes are formed on one end surface of the electrode terminal in the Z-axis direction. It means that the current collector plate is connected to the electrode terminal by the bolt and one screwed bolt. Therefore, as shown in FIG. 9 described later, even when the current collector plate is connected to each of both end faces of the electrode terminal by two through bolts and two screw bolts, This corresponds to the case where the current collector plate is connected to the electrode terminal by a through bolt and one screw bolt.

7 and 8 are exploded perspective views showing the electrode terminal, the current collector plate, and the holding plate. 9 to 11 are sectional views showing various examples of the current collector plate connection structure. 7 shows a case where the current collector is connected to both end faces of the electrode terminal, and FIG. 8 shows a case where the current collector is connected only to one end face of the electrode terminal. 9 to 11 are cross-sectional views perpendicular to the Y-axis direction.

The secondary battery of the first embodiment has two pressing plates 15. The holding plate 15 is an attachment plate attached to the electrode terminal 4 with the current collector plate 13 interposed therebetween. One of the two pressing plates 15 is a pressing plate 15 having a first polarity, and the other is a pressing plate 15 having a second polarity opposite to the first polarity. Therefore, one of the two pressing plates 15 is a pressing plate 15a for the positive electrode, and the other is a pressing plate 15b for the negative electrode. That is, the holding plate 15a is an attachment plate attached to the positive electrode terminal 4a with the current collecting plate 13a interposed therebetween, and the holding plate 15b is an attachment plate attached to the negative electrode terminal 4b with the current collecting plate 13b interposed therebetween.

Preferably, the thickness of the pressing plate 15 is preferably 3 mm or more. Thereby, the rigidity of the member of the pressing plate 15 can be sufficiently secured, and the current collecting plate 13 can be pressed uniformly.

One end surface 41 of the electrode terminal 4 in the Z-axis direction is a connection surface connected to the current collector plate 13. The end surface 41 is a plane perpendicular to the Z-axis direction. Further, the end surface 41 has, for example, a rectangular shape, and the length of the end surface 41 in the X-axis direction is larger than the length of the end surface 41 in the Y-axis direction.

One or more through holes 16 and one or more screw holes 17 are formed on one end face 41 of the electrode terminal 4 in the Z-axis direction. The through-hole 16 is a through-hole that penetrates the electrode terminal 4 from one end face 41 of the electrode terminal 4 and reaches the end face 42 (for example, see FIG. 9) opposite to the end face 41. It is a through-hole for making it penetrate. The screw hole 17 is a screw hole for fastening a screw bolt 19 that is a screw member. The through bolt 18 and the screw bolt 19 are for attaching the pressing plate 15 to the electrode terminal 4. 7 to 9 show an example in which two through holes 16 and one screw hole 17 are formed in the end face 41.

A through hole 161 is formed in the holding plate 15 at a position corresponding to the through hole 16, that is, a position overlapping with the through hole 16 when viewed from the Z-axis direction, and a position corresponding to the screw hole 17, A through hole 171 is formed at a position overlapping the screw hole 17. The through hole 161 is a screw hole for allowing the through bolt 18 to pass therethrough, and the through hole 171 is a screw hole for allowing the screw bolt 19 to pass therethrough.

A through hole 162 is formed at a position corresponding to the through hole 16 in the current collector plate 13, that is, a position overlapping with the through hole 16 when viewed from the Z-axis direction, and a position corresponding to the screw hole 17, That is, a through hole 172 is formed at a position overlapping the screw hole 17. The through hole 162 is a screw hole for allowing the through bolt 18 to pass therethrough, and the through hole 172 is a screw hole for allowing the screw bolt 19 to pass therethrough.

As shown in FIGS. 7 and 8, when the electrode terminal 4 is the positive electrode terminal 4a, a through hole 16a for passing the through bolt 18a and a screw bolt 19a are fastened to one end face 41 of the positive electrode terminal 4a. Screw holes 17a are formed. The through bolt 18a and the screw bolt 19a are for attaching the pressing plate 15a to the positive terminal 4a. Further, in the holding plate 15a, a through hole 161a is formed at a position corresponding to the through hole 16a, and a through hole 171a is formed at a position corresponding to the screw hole 17a. Further, in the current collector plate 13a, a through hole 162a is formed at a position corresponding to the through hole 16a, and a through hole 172a is formed at a position corresponding to the screw hole 17a.

As shown in FIGS. 7 and 8, when the electrode terminal 4 is the negative electrode terminal 4b, a through hole 16b for passing the through bolt 18b and a screw bolt 19b are fastened to one end surface 41 of the negative electrode terminal 4b. Screw holes 17b are formed. The through bolt 18b and the screw bolt 19b are for attaching the holding plate 15b to the negative terminal 4b. Further, in the pressing plate 15b, a through hole 161b is formed at a position corresponding to the through hole 16b, and a through hole 171b is formed at a position corresponding to the screw hole 17b. Further, in the current collector plate 13b, a through hole 162b is formed at a position corresponding to the through hole 16b, and a through hole 172b is formed at a position corresponding to the screw hole 17b.

7 and 8 show an example in which one current collecting plate 13 is disposed between the electrode terminal 4 and the holding plate 15, but for example, as shown in FIG. Between the pressing plate 15, a plurality of current collecting plates 13 may be disposed so as to overlap each other in the Z-axis direction.

Between the electrode terminal 4 and the pressing plate 15 such that the through hole 161, the through hole 162, and the through hole 16 overlap, and the through hole 171, the through hole 172, and the screw hole 17 overlap. A plurality of current collector plates 13 are arranged in an overlapping manner. In this state, the through-bolt 18 is passed through the through-hole 161, the through-hole 162, and the through-hole 16, and the screwed bolt 19 is passed through the through-hole 171 and the through-hole 172. Let Then, the through-hole 161, the through-hole 162, and the through-bolt 18 that penetrates the through-hole 16 are fastened to the nut 20 on the opposite side of the pressing plate 15 across the electrode terminal 4, and the through-hole 171 A screw bolt 19 penetrating through the through hole 172 is fastened to the screw hole 17. Thereby, the holding plate 15 is attached to the electrode terminal 4 with the current collector plate 13 interposed therebetween, and the current collector plate 13 is connected to the electrode terminal 4.

In the examples shown in FIGS. 7 to 9, the second through hole 16 for allowing the second through bolt 18 to pass through is formed in the end face 41 of the electrode terminal 4. Further, a second through hole 161 is formed at a position corresponding to the second through hole 16 in the pressing plate 15, and a position corresponding to the second through hole 16 is formed at the current collecting plate 13. A second through hole 162 is formed. The second through-bolt 18 penetrating the second through-hole 161, the second through-hole 162, and the second through-hole 16 is 2 on the opposite side of the holding plate 15 with the electrode terminal 4 interposed therebetween. By fastening with the second nut 20, the holding plate 15 is attached to the electrode terminal 4 with the current collector plate 13 interposed therebetween, and the current collector plate 13 is connected to the electrode terminal 4.

As shown in FIG. 7 to FIG. 9, the holding plate 15 is attached to the end surface 41 of the electrode terminal 4 with the current collector plate 13 sandwiched by one through bolt 18 and one nut 20. Another pressing plate 15 can be attached to 42 with another current collecting plate 13 interposed therebetween. Accordingly, as shown in FIGS. 7, 9, and 10, one current collector 13 is connected to the end surface 41 of the electrode terminal 4 by one through bolt 18 and one nut 20, and another current collector 13 can be connected to the end face 42 of the electrode terminal 4. Alternatively, as shown in FIG. 8 and FIG. 11, the pressing plate 15 is attached only to the end surface 41 of the electrode terminal 4 with the current collector plate 13 sandwiched between one through bolt 18 and one nut 20. It is also possible to connect the current collector plate 13 only to the end face 41.

As shown in FIG. 11, the thickness of the electrode terminal 4 in the Z-axis direction is defined as a thickness T1. The thickness T1 of the electrode terminal 4 in the Z-axis direction is equal to the length of the through hole 16. Further, the through bolt 18 includes a shaft portion 181 that can be inserted into the through hole 16 and a head portion 182 that cannot be inserted into the through hole 16, and the length of the shaft portion 181 is defined as a length L1. Further, the screw bolt 19 includes a shaft portion 191 that can be inserted into the screw hole 17 and a head portion 192 that cannot be inserted into the screw hole 17, and the length of the shaft portion 191 is L2. And the thickness in the Z-axis direction of the pressing plate 15 arranged on the one end surface 41 side of the electrode terminal 4 and the plurality of current collector plates 13 sandwiched between the one end surface 41 of the electrode terminal 4 and the pressing plate 15. The sum total of each of the thicknesses is defined as a thickness T2. At this time, the length L1 of the shaft portion 181 of the through bolt 18 is larger than the sum of the thickness T1 and the thickness T2. On the other hand, the length L2 of the shaft portion 191 of the screw bolt 19 is smaller than the sum of the thickness T1 and the thickness T2. The length of the screw hole 17 is equal to or longer than the length L2 of the shaft portion 191 of the screw bolt 19.

Due to such a length relationship, the length L1 of the shaft portion 181 of the through bolt 18 becomes larger than the length L2 of the shaft portion 191 of the screw bolt 19. That is, as described above, the through-bolt 18 has a relatively large length, that is, is long, and has a thread or a thread groove formed on the outer peripheral surface of the shaft portion 181, and hence is referred to as a large screw or a long screw. It is a screw member. On the other hand, the screw bolt 19 has a relatively small length, that is, a short screw thread or a screw groove formed on the outer peripheral surface of the shaft portion 191. Therefore, the screw bolt 19 is a screw member called a small screw or a short screw. is there.

In particular, when the thickness T2 is smaller than the thickness T1 and the thickness T2 can be ignored with respect to the thickness T1, the length L1 of the shaft portion 181 of the through bolt 18 is greater than the thickness T1. The length L2 of the shaft portion 191 of the screw bolt 19 is smaller than the thickness T1.

Although not shown in FIGS. 7 to 11, a thread groove or a thread is formed on the inner peripheral surface of the nut 20, and the shaft 181 of the through bolt 18 is opposite to the head 182. A thread or a screw groove is formed on the outer peripheral surface of the portion that is fastened to the nut 20 so as to be screwed with a screw groove or a screw thread formed on the inner peripheral surface of the nut 20. ing.

On the other hand, although not shown in FIGS. 7 to 11, a screw groove or a thread is formed on the inner peripheral surface of the screw hole 17, and the head portion 192 of the shaft portion 191 of the screw bolt 19 is connected to the head portion 192. A thread or screw groove on the outer peripheral surface of the portion on the opposite side, which is fastened to the screw hole 17, is screwed with a screw groove or thread formed on the inner peripheral surface of the screw hole 17. Is formed.

As shown in FIGS. 7 to 9, the nut 20 as a nut member is preferably a double nut. Thereby, it can prevent or suppress that the nut 20 loosens by the high-temperature part and the low-temperature part being periodically generated inside the secondary battery, that is, due to the heat cycle. This is because when the current collector plate 13 is connected to the electrode terminal 4 by fastening the through bolt 18 and the nut 20, the current collector is connected to the electrode terminal 4 rather than the function of electrically connecting the current collector plate 13 to the electrode terminal 4. This is because the function of mechanically connecting, that is, fixing, the plate 13 is more exhibited.

Note that the nut 20 may be a single nut. Alternatively, a through bolt 18 and a nut 20 that have a rotation loosening prevention function or the like can be used.

On the other hand, as described above, the screw hole 17 may be any one in which, for example, a thread groove process is performed on the inner peripheral surface of the screw hole 17 to form a screw groove or a screw thread. It may be a through hole that penetrates 4 and reaches the end face 42. Moreover, it is preferable that the contact area between the screw bolt 19 and the screw hole 17 is large. This is because when the current collector plate 13 is connected to the electrode terminal 4 by fastening the screw bolt 19, the current collector plate is connected to the electrode terminal 4 rather than the function of mechanically connecting the current collector plate 13 to the electrode terminal 4, that is, fixing the current collector plate 13. This is because the function of electrically connecting 13 is more exhibited.

As shown in FIGS. 7 to 9, the screw hole 17 is preferably formed in the center of the end face 41 of the electrode terminal 4. Preferably, one of the two through holes 16 is formed in a portion of the end surface 41 of the electrode terminal 4 that is located on the first side of the center portion of the end surface 41, and the two through holes 16. The other of them is formed in a portion of the end face 41 of the electrode terminal 4 that is located on the opposite side to the first side of the central portion of the end face 41. Thereby, in the end surface 41 which is a connection surface connected with the current collection board 13 among the electrode terminals 4, the uniformity of the pressure by which the current collection board 13 is pressed by the electrode terminal 4 can be improved.

More preferably, the screw hole 17 is formed at the center of gravity of the end face 41 of the electrode terminal 4. Preferably, one of the two through holes 16 is formed in a first position in the end surface 41 of the electrode terminal 4 away from the center of gravity of the end surface 41, and the other of the two through holes 16 is In the end face 41 of the electrode terminal 4, the center is formed at a second position that is symmetrical to the first position with the center of gravity of the end face 41 as the center. Thereby, the uniformity of the pressure by which the current collector plate 13 is pressed against the electrode terminal 4 in the end face 41 can be further improved.

Note that the screw hole 17 is formed at the center of gravity of the end surface 41 means that the screw hole 17 is included in the screw hole 17 when viewed from a direction perpendicular to the end surface 41. 17 is formed. Further, preferably, the screw hole 17 is formed at the center of gravity of the end surface 41. When viewed from a direction perpendicular to the end surface 41, the center of gravity of the end surface 41 corresponds to the center position of the screw hole 17. It means that the screw holes 17 are formed so as to be in the same position. The same applies when the through hole 16 is formed instead of the screw hole 17.

Even if the second position is not symmetrical with the first position around the center of gravity of the end surface 41, the second position is on a straight line connecting the center of gravity of the end surface 41 and the first position, and sandwiches the center of gravity of the end surface 41. In the end position 41, the uniformity of the pressure with which the current collector plate 13 is pressed against the electrode terminal 4 can be improved to some extent.

7 to 9, two through holes 16 and one screw hole 17 are formed in the end face 41 of the electrode terminal 4, and a current collector plate is formed by two through bolts 18 and one screw bolt 19. 13 shows an example in which a pressing plate 15 is attached to the electrode terminal 4 with 13 interposed therebetween. However, as shown in FIG. 10, the number of through bolts 18 and the number of screw bolts 19 are interchanged to form one through hole 16 and two screw holes 17 in the end surface 41 of the electrode terminal 4. The holding plate 15 may be attached to the electrode terminal 4 with the current collecting plate 13 sandwiched between the two through bolts 18 and the two screw bolts 19.

However, when attaching the holding plate 15 to the electrode terminal 4 by fastening the through bolt 18 and the nut 20, compared to attaching the holding plate 15 to the electrode terminal 4 by fastening the screw bolt 19 to the screw hole 17, In the end face 41, the pressure uniformity with which the current collector plate 13 is pressed against the electrode terminal 4 is high. Therefore, as shown in FIG. 10, compared with the case where one through hole 16 and two screw holes 17 are formed in the end surface 41, two end holes 41 are formed in the end surface 41 as shown in FIGS. The case where the hole 16 and one screw hole 17 are formed is more preferable.

However, as shown in FIGS. 7 to 9, even when two through holes 16 and one screw hole 17 are formed on the end surface 41 of the electrode terminal 4, the two through holes 16 are formed into one screw hole 17. On the other hand, when it is arranged to be biased to the same side, the uniformity of the pressure with which the current collector plate 13 is pressed against the electrode terminal 4 in the end face 41 is lowered. Therefore, as described above, it is preferable that the two through holes 16 are formed on the opposite side of the end face 41 with the one screw hole 17 interposed therebetween.

When the connection surface between the electrode terminal 4 and the current collector plate 13, that is, the end surface 41 of the electrode terminal 4 has a rectangular shape, the diameter of the through hole 16 is smaller than the length of the short side of the end surface 41, and The diameter of the head of the bolt 18 is smaller than the length of the short side of the end surface 41. The diameter of the through hole 16 is equal to or greater than a lower limit value at which the current collector plate 13 can be connected to the electrode terminal 4 with sufficient mechanical strength by fastening the through bolt 18 and the nut 20. The diameter of the portion is equal to or greater than the lower limit value at which the current collector plate 13 can be connected to the electrode terminal 4 with sufficient mechanical strength by fastening the through bolt 18 and the nut 20.

<First modification of current collector connection structure>
Next, a first modification of the current collector plate connection structure will be described. In the first modification, two holes are formed in the current collector plate, and the case where the current collector plate is connected to the electrode terminal by one through bolt and one screw bolt will be described as an example. To do. In addition to the arrangement of the through bolts and screw bolts, the current collector plate is electroded by the two through bolts and one screw bolt described above, or by one through bolt and two screw bolts. This is the same as when connected to a terminal.

12 to 14 are cross-sectional views showing various examples of the current collector plate connection structure. 12 to 14 are cross-sectional views perpendicular to the Y-axis direction.

As shown in FIGS. 12 to 14, in the first modification, one through hole 16 and one screw hole 17 are formed in one end surface 41 of the electrode terminal 4 in the Z-axis direction. . As shown in FIGS. 12 and 13, the pressing plate 15 is attached to the end surface 41 of the electrode terminal 4 with the current collector plate 13 sandwiched between the one through bolt 18 and one nut 20, and the electrode terminal 4. Another holding plate 15 can be attached to the end face 42 with another current collecting plate 13 interposed therebetween. Therefore, as shown in FIGS. 12 and 13, one current collector 13 is connected to the end surface 41 of the electrode terminal 4 by one through bolt 18 and one nut 20, and another current collector 13 is connected to the electrode. It can be connected to the end face 42 of the terminal 4. Alternatively, as shown in FIG. 14, with one through bolt 18 and one nut 20, the pressing plate 15 is attached only to the end surface 41 of the electrode terminal 4 across the current collector plate 13, and the end surface 41 of the electrode terminal 4 is attached. It is also possible to connect the current collector plate 13 only to the above.

Further, as shown in FIG. 13, the position of the center of gravity of the end face 41 in the X-axis direction can be made different from the position of the center of gravity of the end face 42 in the X-axis direction. For example, the position of the center of gravity of the end surface 41 in the X-axis direction can be determined by chamfering each of the pair of corners located diagonally to the rectangular electrode terminal 4 when viewed from the Y-axis direction. It can be different from the position of the center of gravity of the end face 42 in the axial direction.

Preferably, the through hole 16 is formed in a portion of the end surface 41 of the electrode terminal 4 that is located on the first side of the center portion of the end surface 41, and the screw hole 17 is formed on the end surface 41 of the electrode terminal 4. Among these, it is formed in a portion located on the opposite side to the first side of the central portion of the end face 41. Thereby, in the end surface 41 which is a connection surface connected with the current collection board 13 among the electrode terminals 4, the uniformity of the pressure by which the current collection board 13 is pressed by the electrode terminal 4 can be improved.

More preferably, the through hole 16 is formed at a first position away from the center of gravity of the end surface 41 within the end surface 41 of the electrode terminal 4, and the screw hole 17 is formed at the end surface 41 within the end surface 41 of the electrode terminal 4. The center of gravity 41 is formed at a second position that is symmetrical to the first position. Thereby, the uniformity of the pressure by which the current collector plate 13 is pressed against the electrode terminal 4 in the end face 41 can be further improved.

Even if the second position is not centered on the center of gravity of the end surface 41, the second position is on a straight line connecting the center of gravity of the end surface 41 and the first position, and the center of gravity of the end surface 41 is sandwiched between them. In the end position 41, the uniformity of the pressure with which the current collector plate 13 is pressed against the electrode terminal 4 can be improved to some extent. Alternatively, the second position may be a position symmetrical to the first position around a straight line passing through the center of gravity of the end surface 41 and parallel to the Y-axis direction. At this time, the first position and the second position are the positions of both ends of the fan-shaped arc with the center of gravity of the end surface 41 as the center.

<Second modification of current collector connection structure>
Next, a second modification of the current collector connection structure will be described. In the second modification, four holes are formed in the current collector plate, and the current collector plate is connected to the electrode terminal by two through bolts and two screw bolts. In addition to the arrangement of the through bolts and the screw bolts, the current collector plate is formed by the two through bolts and one screw bolt described above, or by one through bolt and two screw bolts. This is the same as when connected to the electrode terminal.

FIG. 15 is an exploded perspective view showing an electrode terminal, a current collector plate, and a holding plate.

As shown in FIG. 15, in the second modification, two end holes 41 and two screw holes 17 are formed on one end face 41 of the electrode terminal 4 in the Z-axis direction. In addition, as shown in FIG. 15, the holding plate 15 is attached to the end surface 41 of the electrode terminal 4 with the current collector plate 13 sandwiched between one through bolt 18 and one nut 20, and the end surface 41 of the electrode terminal 4 is attached. Another holding plate 15 can be attached to the end surface opposite to the other current plate 13 with another current collecting plate 13 interposed therebetween. Therefore, one current collector 13 is connected to the end surface 41 of the electrode terminal 4 by one through bolt 18 and one nut 20, and another current collector 13 is connected to the end surface 41 opposite to the electrode terminal 4. Can be connected to the end face. Or although illustration is abbreviate | omitted, the pressing board 15 is attached only to the end surface 41 of the electrode terminal 4 on both sides of the current collecting plate 13 by one through volt | bolt 18 and one nut 20, and only the end surface 41 of the electrode terminal 4 is attached. It is also possible to connect the current collector plate 13.

Table 1 shows an example of an arrangement pattern of two through bolts and two screw bolts in the end face 41 of the electrode terminal 4. In Table 1, for the four patterns from the pattern PT1 to the pattern PT4, four positions arranged from one side to the other side in the X-axis direction, that is, from the left side to the right side, are sequentially arranged as a left end position PS1 and a left middle position PS2. The middle right position PS3 and the right end position PS4. In Table 1, when a through bolt is disposed at a position among the left end position PS1, the left middle position PS2, the right middle position PS3, and the right end position PS4, the through hole 16 is formed at that position. Means that In Table 1, when a screw bolt is arranged at a position among the left end position PS1, the left middle position PS2, the right middle position PS3, and the right end position PS4, a screw hole 17 is formed at that position. Means that

In the case shown in the pattern PT1 of Table 1, that is, as shown in FIG. 15, the right middle position PS3 where the screw hole 17 is formed is preferably the left middle position PS2 where another screw hole 17 is formed, and the end face 41. It is a position on the opposite side across the center part of. Thereby, in the end surface 41 which is a connection surface connected with the current collection board 13 among the electrode terminals 4, the uniformity of the pressure by which the current collection board 13 is pressed by the electrode terminal 4 can be improved. The case shown in the pattern PT4 in Table 1 is the same as the case shown in the pattern PT1 in Table 1 except that the through bolts and the screw bolts are replaced with each other.

In the case shown in the pattern PT1 of Table 1, that is, as shown in FIG. 15, the right end position PS4 where the through hole 16 is formed is more preferably the left end position PS1 where another through hole 16 is formed, and the end face 41. It is a symmetric position around the center of gravity. The right middle position PS3 in which the screw hole 17 is formed is a symmetric position with respect to the left middle position PS2 in which another screw hole 17 is formed with the center of gravity of the end surface 41 as the center. Thereby, the uniformity of the pressure by which the current collector plate 13 is pressed against the electrode terminal 4 in the end face 41 can be further improved. The case shown in the pattern PT4 in Table 1 is the same as the case shown in the pattern PT1 in Table 1 except that the through bolts and the screw bolts are replaced with each other.

In addition, even in the case of the patterns PT2 and PT3 in Table 1, a combination of the types of the through holes 16 or screw holes 17 formed at the left end position PS1 and the left middle position PS2, and the right middle position PS3 and the right end position PS4 are formed. The combination of the type of the through-hole 16 or the screw hole 17 made becomes the same. Therefore, when the right middle position PS3 is a position opposite to the left middle position PS2 across the central portion of the end face 41, the effect is slightly reduced as compared with the patterns PT1 and PT4 in Table 1. The effect of improving the uniformity of the pressure with which the electric plate 13 is pressed against the electrode terminal 4 can be obtained to some extent.

<Comparison with the case where only one of the through bolt and screw bolt is used>
For example, consider the case where the current collector plate 13 is connected to the electrode terminal 4 using only the through bolts 18. In this case, the current collector plate 13 can be mechanically reliably connected to the electrode terminal 4, that is, fixed. However, when a plurality of current collecting plates 13 are disposed between the holding plate 15 and the electrode terminal 4, the contact resistance between each of the current collecting plates 13 and the electrode terminal 4 may increase. The current value at the time of charging / discharging cannot be increased easily.

On the other hand, the case where the current collector plate 13 is connected to the electrode terminal 4 using only the screw bolt 19 will be considered. In this case, the current collector plate 13 can be electrically connected to the electrode terminal 4 reliably. However, there is a possibility that the screw bolt 19 is loosened due to minute vibrations continuously applied to the secondary battery from the outside or the secondary battery generating heat due to charging / discharging. Here, it is not easy to prevent the screw bolt 19 from loosening. Therefore, the variation in the contact resistance between the current collector plate 13 and the electrode terminal 4 becomes large, and the reliability of the secondary battery may be reduced.

In the first embodiment, the current collector plate 13 is connected to the electrode terminal 4 by using both the through bolt 18 and the nut 20 and the screwed bolt 19 together. At this time, by fastening the through bolt 18 and the nut 20, variation in contact resistance between the current collector plate 13 and the electrode terminal 4 can be reduced. Moreover, the current value at the time of charging / discharging can be easily increased by fastening the screw bolt 19. Therefore, in the secondary battery, safety and reliability can be improved while ensuring a sufficiently large current value for charging and discharging.

In addition, when the current collector plate 13 is connected to the electrode terminal 4 without using the holding plate 15, the current collector plate 13 in a part away from the through bolt 18 or the screw bolt 19 may not come into contact with the electrode terminal 4. Therefore, the contact resistance between each of the current collector plates 13 and the electrode terminals 4 may increase, and the current value at the time of charging / discharging cannot be easily increased.

In the first embodiment, the current collecting plate 13 is connected to the electrode terminal 4 using the holding plate 15. The area of the pressing plate 15 is substantially the same as the end face 41 of the electrode terminal 4. Thereby, in the end surface 41 which is a connection surface connected with the current collection board 13 among the electrode terminals 4, the uniformity of the pressure by which the current collection board 13 is pressed by the electrode terminal 4 can be improved, and charging / discharging is carried out. The current value at the time of performing can be easily increased. Therefore, in the secondary battery, safety and reliability can be improved while ensuring a sufficiently large current value for charging and discharging.

The current collector plate connection structure described above can also be applied to the case where the current collector plate 13 is connected to only one of the positive electrode terminal 4a and the negative electrode terminal 4b. Further, even when the above-described current collector plate connection structure is applied to only one of the positive electrode terminal 4a and the negative electrode terminal 4b, the above-described current collector plate connection structure is applied to either the positive electrode terminal 4a or the negative electrode terminal 4b. Compared with the case where no is applied, the applied electrode terminal 4 can improve the uniformity of the pressure with which the current collector plate 13 is pressed against the electrode terminal 4. Therefore, in the secondary battery, safety and reliability can be improved while ensuring a sufficiently large current value for charging and discharging.

<Example of Embodiment 1>
Next, examples of the secondary battery as the lithium ion battery in the first embodiment will be described.

The lithium ion battery of the example of the first embodiment was manufactured in the same manner as the lithium ion battery described in the first embodiment. Specifically, the electrode small bundle 11 in which one positive electrode plate 6a and one negative electrode plate 6b are laminated via the separator 8 is laminated by fifteen bundles in the Z-axis direction of FIG. A bundle 12 was formed. At this time, the current collecting tabs 10a of the 15 positive electrode plates 6a are collectively connected to the current collecting plate 13a for the positive electrodes by ultrasonic welding, and the current collecting tabs 10b of the 16 negative electrode plates 6b are for the negative electrode. The small electrode group 14 was formed by being collectively connected to the current collector plate 13b by ultrasonic welding. Then, 16 electrode bundles 12, that is, 16 small electrode groups 14 were arranged in the Z-axis direction of FIG. 1 to form an electrode group 9, thereby producing a lithium ion battery.

The shape of the end surface 41 of the electrode terminal 4 when viewed from the Z-axis direction is a rectangular shape, that is, a rectangular shape, and the length in the X-axis direction is larger than the length in the Y-axis direction. Then, of the 16 bundles of

small electrode groups

14, 8 bundles of small electrode groups 14, that is, 8 current collector plates 13 are connected to the end face 41, and the remaining 8 bundles of small electrode groups 14, that is, 8 sheets. The current collector plate 13 was connected to the end face 42. Further, unless otherwise specified, the through bolt 18 was fastened with a nut 20 made of a double nut.

As an electrolytic solution, a solution of a mixture of ethylene carbonate and dimethyl carbonate, was prepared by dissolving lithium hexafluorophosphate (LiPF _6). A polyethylene porous material was used as the separator.

<Example 1>
A secondary battery of Example 1 was produced. In the secondary battery of Example 1, the current collector plate 13 was connected to the electrode terminal 4 by two through bolts 18 and one screw bolt 19. For example, as shown in FIG. 11, the screw hole 17 is formed at the center of gravity of the end surface 41 of the electrode terminal 4. Of the end surface 41, two positions symmetrical to each other about the center of gravity of the end surface 41 in the X-axis direction are formed. A through hole 16 was formed in each.

As described above, the current collector plate 13 is connected to the electrode terminal 4 by the two through bolts 18 and the single screw bolt 19. That is, the end surface 41 and the end surface 42 of the electrode terminal 4. This means that the current collector plate 13 is connected to the electrode terminal 4 by two through bolts 18 and one screw bolt 19 on one end face.

<Comparative Example 1>
On the other hand, a secondary battery of Comparative Example 1 was produced. The secondary battery of Comparative Example 1 differs from the secondary battery of Example 1 in that the current collector plate 13 is connected to the electrode terminal 4 by only two through bolts 18.

<Measurement of resistance between electrode terminal and current collector>
The contact resistance between the current collector plate 13 and the electrode terminal 4 was measured for the secondary batteries of Example 1 and Comparative Example 1 thus manufactured. The result is shown in the graph of FIG. The horizontal axis in FIG. 16 indicates the position of the current collector plate 13, and the vertical axis in FIG. 16 indicates the resistance value of the contact resistance between the current collector plate 13 and the electrode terminal 4. In the horizontal axis of FIG. 16, the eight current collecting plates 13 that are arranged in the Z-axis direction and are arranged between the electrode terminal 4 and the holding plate 15 are closest to the end surface 41 of the electrode terminal 4. The one disposed at the position is displayed as the first sheet, and the one disposed farthest from the end face 41 of the electrode terminal 4 is displayed as the eighth sheet. Further, the resistance value shown on the vertical axis of FIG. 16 is normalized by the resistance value between the fifth current collecting plate 13 and the electrode terminal 4 in Comparative Example 1.

In the case of Comparative Example 1 in FIG. 16, the resistance value of the third to sixth current collector plates 13 is larger than the resistance value of the first, second, seventh and eighth current collector plates 13. This is because, when the current collector plate 13 is connected to the electrode terminal 4 only by the through bolts 18, the two through bolts 18 of the current collector plate 13 become farther away from both the end face 41 and the holding plate 15. It is considered that the portions apart from each other are difficult to contact each other and the contact resistance increases.

On the other hand, in the case of Example 1 in FIG. 16, the resistance value between the current collector plate 13 and the electrode terminal 4 is almost less than half in all of the first to eighth current collector plates 13 as compared with Comparative Example 1. Decreased. Therefore, the resistance value between the current collector plate 13 and the electrode terminal 4 could be reduced by connecting the current collector plate 13 to the electrode terminal 4 with the screw bolt 19.

<Example 2>
A plurality of secondary batteries of Example 2 were produced. In the secondary battery of Example 2, the current collector plate 13 was connected to the electrode terminal 4 by one through bolt 18 and one screw bolt 19. For example, as shown in FIG. 14, each of the through hole 16 and the screw hole 17 is formed at each of two positions symmetrical to each other about the center of gravity of the end surface 41 in the X-axis direction among the end surfaces 41 of the electrode terminal 4. It was done.

As described above, the current collector plate 13 is connected to the electrode terminal 4 by one through bolt 18 and one screw bolt 19. That is, the end face 41 and the end face 42 of the electrode terminal 4. It means that the current collector plate 13 is connected to the electrode terminal 4 by one through bolt 18 and one screw bolt 19 on one end face.

<Example 3>
A plurality of secondary batteries of Example 3 were produced. In the secondary battery of Example 3, the current collector plate 13 is connected to the electrode terminal by two through bolts 18 and one screw bolt 19 or by one through bolt 18 and two screw bolts 19. 4 connected. As shown in FIG. 9, the screw hole 17 is formed at the center of gravity of the end surface 41 of the electrode terminal 4. Of the end surface 41, each of two positions symmetrical to each other about the center of gravity of the end surface 41 in the X-axis direction. In addition, a through hole 16 was formed. Alternatively, as illustrated in FIG. 10, the through hole 16 is formed at the center of gravity of the end surface 41 of the electrode terminal 4, and two positions of the end surface 41 that are symmetrical with respect to the center of gravity of the end surface 41 in the X-axis direction. A screw hole 17 was formed in each of these.

As described above, the current collector plate 13 is connected to the electrode terminal 4 by the two through bolts 18 and the single screw bolt 19. That is, the end surface 41 and the end surface 42 of the electrode terminal 4. This means that the current collector plate 13 is connected to the electrode terminal 4 by two through bolts 18 and one screw bolt 19 on one end face. In addition, the fact that the current collector plate 13 is connected to the electrode terminal 4 by one through bolt 18 and two screw bolts 19 means that one of the end face 41 and the end face 42 of the electrode terminal 4 is It means that the current collector plate 13 is connected to the electrode terminal 4 by one through bolt 18 and two screw bolts 19.

<Measurement of electrode terminal temperature during discharge>
Thus, about the secondary battery of Example 2 and 3 produced, the temperature of the electrode terminal 4 at the time of discharging was measured. Specifically, a secondary battery is installed in a convection thermostat whose ambient environmental temperature is 25 ° C., the discharge current is set to 500 A, and the voltage at the time of stopping the discharge, that is, the end voltage is set to 3.0 V. Then, the temperature of the electrode terminal 4 was measured. Moreover, the thermocouple was attached as a temperature sensor to the part to which the bus-bar which consists of a copper plate connected to the electricity cable among the electrode terminals 4 is fastened, that is, the fastening part, and the temperature of the electrode terminal 4 was measured by the thermocouple. . The result is shown in FIG. The horizontal axis of FIG. 17 shows the battery resistance of the secondary battery, that is, the contact resistance between the current collector plate and the electrode terminal, and the vertical axis of FIG. 17 shows the temperature rise of the electrode terminal when discharging is performed. . Moreover, the battery resistance shown on the horizontal axis of FIG. 17 is normalized by the average value of the battery resistance in Example 2.

In the secondary battery of Example 2, the battery resistance is 1.2 to 1.4 mΩ, the temperature of the electrode terminal 4 is 55 to 85 ° C., and in the secondary battery of Example 3, the battery resistance is 0.8. The temperature of the electrode terminal 4 was 40 to 50 ° C. As shown in FIG. 17, the standardized battery resistance in Example 2 is about 1.5 times the standardized battery resistance in Example 3, and the temperature rise in Example 2 It was greater than the temperature rise at 3. That is, for example, when discharging is performed with a large discharge current of 500 A, the temperature rise in the secondary battery of Example 3 in which a total of three through bolts 18 and screw bolts 19 are used is connected to the through bolt 18 and the screw bolt. 19 is smaller than the temperature rise in the secondary battery of Example 2 connected using one by one.

<Example 4>
A plurality of secondary batteries of Example 4 were produced. In the secondary battery of Example 4, the current collector plate 13 was connected to the electrode terminal 4 using a total of 2 to 4 through bolts 18 and screw bolts 19. When a total of two through bolts 18 and screw bolts 19 are used, each of the end faces 41 of the electrode terminals 4 has through holes at two positions symmetrical to each other about the center of gravity of the end face 41 in the X-axis direction. 16 and screw holes 17 were formed. When a total of three through bolts 18 and screw bolts 19 are used, the through hole 16 or the screw hole 17 corresponds to the type in which only one of the through bolt 18 and the screw bolt 19 is used. The center of gravity of the end face 41 of the terminal 4 was formed. Further, among the end faces 41 of the electrode terminals 4, it corresponds to the type in which two of the through bolts 18 and the screw bolts 19 are used at each of two positions symmetrical with respect to the center of gravity of the end face 41 in the X-axis direction. Thus, the through hole 16 or the screw hole 17 was formed. Further, when a total of four through bolts 18 and screw bolts 19 were used, the through holes 16 or the screw holes 17 were formed corresponding to the patterns PT1 to PT4 described above using Table 1. In Example 4, in either case, the through bolt 18 and the nut 20 made of a double nut were fastened.

As described above, the current collector plate 13 is connected to the electrode terminal 4 by using a total of 2 to 4 through bolts 18 and screw bolts 19. It means that the total of the number of through bolts 18 and the number of screw bolts 19 used for connecting the current collector plate 13 to the electrode terminal 4 is 2 to 4 on one end face.

<Comparative example 2>
On the other hand, a plurality of secondary batteries of Comparative Example 2 were produced. In the secondary battery of Comparative Example 2, the current collector plate 13 was connected to the electrode terminal 4 using a total of 2 to 4 through bolts 18. The secondary battery of Comparative Example 2 differs from the secondary battery of Example 4 in that the current collector plate 13 is connected to the electrode terminal 4 only by the through bolts 18. In the secondary battery of Comparative Example 2, the through bolt 18 and the nut 20 made of a double nut were fastened.

<Comparative Example 3>
A plurality of secondary batteries of Comparative Example 3 were produced. In the secondary battery of Comparative Example 3, the current collector plate 13 was connected to the electrode terminal 4 using a total of 2 to 4 screw bolts 19. The secondary battery of Comparative Example 3 differs from the secondary battery of Example 4 in that the current collector plate 13 is connected to the electrode terminal 4 only by the screw bolts 19.

<Comparative example 4>
On the other hand, a plurality of secondary batteries of Comparative Example 4 were produced. In the secondary battery of Comparative Example 4, the current collector plate 13 was connected to the electrode terminal 4 using a total of 2 to 4 through bolts 18. The secondary battery of Comparative Example 4 differs from the secondary battery of Example 4 in that the current collector plate 13 is connected to the electrode terminal 4 only by the through bolts 18. In the secondary battery of Comparative Example 4, the through bolt 18 and the nut 20 made of a single nut were fastened.

<Looseness of screw bolts, etc. by heat cycle test>
With respect to the secondary batteries of Example 4 and Comparative Examples 2 to 4 manufactured as described above, the looseness of screwed bolts or the like in the heat cycle test was evaluated. Specifically, after heating at 80 ° C. and cooling at −40 ° C. are repeated a plurality of times, the resistance value of the contact resistance between the current collector plate 13 and the electrode terminal 4 is measured. Then, based on the measured resistance value, it was evaluated whether or not loosening such as a screwed bolt occurred. The results are shown in Table 2.

In Table 2, ○ indicates a case where no loosening of the screwed bolt or the like has occurred, and × indicates a case where the loosening of the screwed bolt or the like has occurred. △ indicates a case where the resistance value between the current collector plate and the electrode terminal is between the resistance value in the case of ◯ and the resistance value in the case of ×, and ◎ indicates that the resistance value between the current collector plate and the electrode terminal The case where the resistance value between them is smaller than the resistance value in the case of ◯ is shown.

As shown in Table 2, in the case of Comparative Example 3, that is, when only the screw bolt 19 is used, the screw bolt 19 is loosened or the screw bolt 19 is not loosened. In comparison, the resistance value between the current collector plate 13 and the electrode terminal 4 was increased. On the other hand, in the case of Comparative Example 2, Example 4 and Comparative Example 4, that is, when at least one through bolt 18 is used, compared with Comparative Example 3 in which no through bolt 18 is used, screwed bolt 19 or through bolt. 18 slack was difficult to occur. In Comparative Example 2, Example 4, and Comparative Example 4, when the total number of through bolts 18 and screw bolts 19 was three or more, the looseness of the screw bolts and the like was approximately the same.

Summarizing the above results, as shown in FIG. 17, for example, when discharging is performed with a large discharge current of 500 A, the total number of through bolts 18 and screw bolts 19 is preferably three or more. Further, when the total number of through bolts 18 and screw bolts 19 is three or more, as shown in Table 2, the use of at least one through bolt 18 prevents loosening of the screw bolts 19 and the like. can do. Furthermore, as shown in FIG. 16, the resistance value between the current collector plate 13 and the electrode terminal 4 can be reduced by using at least one screw bolt 19.

<Main features and effects of the present embodiment>
In the secondary battery of the first embodiment, the current collector plate connected to the electrode plate is sandwiched between the electrode terminal and the holding plate, and one or more screw bolts are fastened to the screw holes, and When one or more sets of through bolts and nuts are fastened, the pressing plate is attached to the electrode terminal, and the current collecting plate is pressed against the electrode terminal by the pressing plate and connected. By attaching a holding plate with a through bolt, vibration from the outside is applied, or when heating and cooling are repeated during charging and discharging, the force holding the current collecting plate is loosened. Can be prevented. Moreover, the contact resistance between the current collector plate and the electrode terminal can be reduced by attaching the holding plate with the screw bolt. As a result, even if the current collector plate is not connected to the electrode terminal by welding, the current collector plate can be connected to the electrode terminal by a simple connection method, and the contact resistance between the current collector plate and the electrode terminal is reduced. It is possible to charge and discharge by flowing a large current.

Furthermore, according to the first embodiment, since it is not necessary to perform welding after fixing the current collector plate to the electrode terminal, there is no possibility that metal pieces generated from the electrode terminal are mixed into the electrode group. In this way, the electrode plate is connected to the electrode terminal by a simple connection method that does not use welding, and a secondary battery having both high safety and high reliability can be provided.

(Embodiment 2)
In the secondary battery of the first embodiment, the current collector plate connected to each of the plurality of electrode bundles is connected to the electrode terminal using a through bolt and a screw bolt so as to be connected to the electrode terminal with low resistance. Was connected. On the other hand, in the secondary battery of the second embodiment, the plurality of electrode bundles are arranged so that the positive plates located at both ends of the electrode bundle do not face each other. The second embodiment is an embodiment when the present invention is applied to a lithium ion battery as a secondary battery.

In general, a lithium ion battery has a structure in which a plurality of positive and negative electrode plates are alternately stacked via a separator for preventing short circuit in a battery can (stacked type), and a positive electrode plate and a negative electrode plate on a shaft. A structure wound around a separator is known.

In the laminated lithium ion battery, tabs for connecting the electrode plate and the terminal are formed on each end of the positive electrode plate and the negative electrode plate. And the positive electrode terminal and the negative electrode terminal are provided on the lower surface and the upper surface of the battery can lid plate, and the positive electrode terminal and the negative electrode terminal arranged on the lower surface of the battery can cover plate are joined to the tab of the positive electrode plate and the tab of the negative electrode plate, respectively. .

However, the number of electrode plates accommodated in the battery can increases as the capacity of the laminated lithium ion battery used for power storage and the like increases. Therefore, when the electrode plate tab is joined to the terminal, the deterioration of the battery characteristics accompanying the increase in the contact resistance of the joint is a problem. Moreover, it is necessary to join all the positive electrode tabs and the negative electrode tabs to the positive electrode terminal and the negative electrode terminal in the manufacturing process, respectively. Furthermore, when the number of electrode plate tabs increases, the bonding with the terminals becomes insufficient, and the internal resistance may increase and become defective.

To deal with such a problem, as described above, for example, in Patent Document 4, the positive electrode plate and the negative electrode plate are divided into a plurality of sets (hereinafter referred to as electrode groups) for each predetermined number of sheets, and a tab and a current collecting lead for each predetermined number of sheets. After that, the electrode group is housed in a battery can, the other end of the current collecting lead is fixed to the positive terminal and the negative terminal with a bolt, and the current collecting lead and the terminal are welded to produce a lithium ion battery. ing. In Patent Document 5, a non-aqueous electrolyte in which lithium hexafluorophosphate of a lithium salt is dissolved in an organic solvent is injected into a battery can as a non-aqueous electrolyte for a lithium ion battery. The technology is described.

However, when an electrode group divided into a plurality of groups for each predetermined number is stored in a battery can and fixed to a terminal with a current collector lead, for example, both end surfaces in the stacking direction of the electrode group are formed with a positive electrode plate and stored in the battery can. In this case, the positive electrode plates face each other on the surface where the other end of the electrode group faces. In such a case, contact between the positive electrodes may cause product defects such as safety problems such as internal short circuits. In addition, if the current collector lead is fixed to the terminal with a bolt and then welding is performed on the bolt and the terminal, there is a possibility that the contact resistance at the joint between the bolt and the terminal may increase because the bolt tightening and welding positions overlap. . Further, there is a risk that metal pieces generated during welding enter the inside of the battery can and cause an internal short circuit.

In the second embodiment, the first problem is to prevent a short circuit during charging / discharging. The second problem is a secondary battery that prevents a short circuit that is likely to occur due to an operation at the time of manufacture in addition to the above-mentioned purpose, and that has higher safety by reducing the contact resistance between the electrode plate tab and the terminal base portion. The purpose is to provide.

<Battery can>
FIG. 18 is a perspective view of a battery can of the lithium ion battery according to the second embodiment. The lithium ion battery includes a positive electrode terminal 51 a and a negative electrode terminal 51 b as terminals 51 (see FIG. 19 described later), a liquid injection port 52, a cleavage valve 53, a battery can 54, and a battery lid 55.

As shown in FIG. 18, the battery can 54 has a prismatic shape with one surface opened, and includes a battery lid 55 that closes the opening of the battery can 54. The battery can 54 and the battery lid 55 are sealed by welding the opening peripheral portion of the battery can 54 and the battery lid 55 after inserting the power generation element 56 (see FIG. 20 described later) into the battery can 54. The material of the battery can is preferably a metal material such as an aluminum material in addition to a stainless steel material in terms of mechanical strength. The battery lid 55 is provided with a cleavage valve 53 and a liquid injection port 52. The cleavage valve 53 has a function of releasing the internal gas when the temperature of the lithium ion battery rises for some reason, such as an internal short circuit, and the internal pressure in the battery can rises above a predetermined pressure.

From the injection port 52, lithium hexafluorophosphate (LiPF ₆ ) is added to a solution obtained by mixing one or more cyclic carbonate organic solvents such as ethylene carbonate and chain carbonate organic solvents such as dimethyl carbonate. Then, a nonaqueous electrolytic solution in which a lithium salt such as lithium tetrafluoroborate (LiBF ₄ ) is dissolved is injected. After injection of the non-aqueous electrolyte, the liquid injection port 52 is sealed with a liquid port stopper.

<Power generation element>
19 and 20 are cross-sectional views of the lithium ion battery of the second embodiment. 19 is a cross-sectional view perpendicular to the direction perpendicular to the stacking direction of the positive electrode plate and the negative electrode plate, and FIG. 20 is a cross-sectional view perpendicular to the stacking direction of the positive electrode plate and the negative electrode plate. That is, FIG. 20 shows a cross-sectional view of a lithium ion battery in which the battery can 54 is cut in parallel with the laminated surface of the positive electrode plate and the negative electrode plate. FIG. 21 is a perspective view of the power generation element with the battery can removed. FIG. 22 is a perspective view of the lithium ion battery with the battery can removed.

19 and 20, a power generation element 56 is accommodated in the battery can 54. As shown in FIG. 21, the power generation elements 56 are alternately stacked via positive electrodes 57a, negative electrodes 57b, and separators (not shown) so that the positive electrodes and the negative plates do not directly contact and short-circuit. Point to.

The positive electrode plate 57a has a positive electrode current collector made of an aluminum foil formed in a plate shape, and a mixture layer containing a positive electrode active material, a binder, and a conductive agent provided on both surfaces of the positive electrode current collector.

As the positive electrode active material, 1) one represented by the chemical formula LiMO ₂ (M is at least one transition metal) or 2) spinel manganese can be used. 3) A part of Mn, Ni, Co, etc. in the positive electrode active material such as lithium manganate, lithium nickelate, lithium cobaltate and the like can be substituted with one or more transition metals. . Further, a part of the transition metal of 3) substituted with a metal element such as Mg or Al can also be used. In addition, phosphate compounds, LiFePO ₄ , LiMnPO ₄ , LiMn _X M _1-X PO ₄ (0.3 ≦ x ≦ 1, M is Li, Fe, Ni, Co, Ti, Cu, Zn, Mg, And one or more elements selected from Zr) can be used.

As the conductive agent, a known conductive agent can be used. For example, a carbon-based conductive agent such as graphite, acetylene black, carbon black, or carbon fiber can be used. However, it is not limited to these materials.

As the binder, a known binder can be used. For example, polyvinylidene fluoride, styrene-butadiene rubber, isoprene rubber, or the like can be used. However, it is not limited to these materials. In Embodiment 2, a metal oxide lithium manganate is used as a positive electrode active material, polyvinylidene fluoride (hereinafter referred to as PVDF) is used as a binder, and acetylene black is used as a conductive material, that is, a conductive agent.

At one end of the positive electrode current collector, a positive electrode tab 58a that is an electrode tab, that is, an electrode plate tab 58 (see FIG. 23 described later) is formed. When using a method in which the positive electrode tab 58a is electrically connected to the positive electrode terminal 51a via the positive electrode current collector plate 61a, one end of the positive electrode tab 58a is connected to one end of the positive electrode current collector plate 61a by ultrasonic welding or laser welding. Etc. are used for joining. When the positive electrode tab 58a and the positive electrode terminal 51a are electrically connected by friction stir welding, the positive electrode current collector plate is not used and the positive electrode terminal base 51a is directly joined.

The battery lid 55 is provided with a positive electrode terminal 51a that communicates the inside and outside of the battery lid 55 of the lithium ion battery, and is formed of, for example, an aluminum-based material.

The negative electrode plate 57b is a plate-shaped material having high conductivity and flexibility, for example, a negative electrode current collector made of copper or nickel, a negative electrode active material and a binder provided on both surfaces of the negative electrode current collector, And a mixture layer containing a conductive agent. The negative electrode active material includes 1) a carbon-based material such as graphite or amorphous carbon, 2) an oxide-based material such as Li ₄ Ti ₅ O ₁₂ , and 3) a metal / alloy system such as tin or silicon. Materials can be used. As the conductive agent, a known conductive agent can be used. For example, a carbon-based conductive agent such as graphite, acetylene black, carbon black, or carbon fiber can be used. However, it is not limited to these materials.

As the binder, a known binder can be used. For example, polyvinylidene fluoride, styrene-butadiene rubber, isoprene rubber, or the like can be used. However, it is not limited to these materials.

In Embodiment 2, graphite is used as the negative electrode active material, PVDF is used as the binder, and conductive material, that is, acetylene black is used as the conductive agent. At one end of the negative electrode current collector, a negative electrode tab 58b which is an electrode tab, that is, an electrode plate tab 58 (see FIG. 23 described later) is formed. Similarly to the positive electrode tab 58a, the negative electrode tab 58b is connected to the negative electrode terminal 51b via the negative electrode current collector plate 61b, and one end of the negative electrode tab 58b is connected to the negative electrode current collector plate 61b. Join one end using ultrasonic welding or laser welding. When the negative electrode tab 58b and the negative electrode terminal 51b are electrically connected using friction stir welding, the negative electrode current collector plate is not used, and the negative electrode tab base portion 51'b is directly joined.

The battery lid 55 is provided with a negative electrode terminal 51b that communicates the inside and outside of the lithium ion battery. The negative electrode terminal 51b is made of, for example, a copper-based or nickel-based material. As shown in FIG. 20, the positive electrode tab 58a and the negative electrode tab 58b are arranged apart from each other so as not to overlap each other.

The separator (not shown) is formed in a sheet shape from a porous material such as polyolefin or non-woven fabric through which lithium ions can pass. Examples of the polyolefin separator include polypropylene and polyethylene, and examples of the nonwoven fabric separator include glass and paper. The separator has a size that can prevent the positive electrode plate 57a and the negative electrode plate 57b from contacting each other in a stacked state. (In FIG. 21, two positive plates and two negative plates are shown for ease of illustration, but the number of positive plates, negative plates and separators is the lithium ion battery to be manufactured. (For example, when the battery capacity is several hundred Ah, several hundred positive and negative plates are laminated.)

As far as the present embodiment 2 is concerned, it is not necessary to prepare a special electrolyte solution. For example, the electrolyte solution may be an electrolyte solution produced by the means disclosed in Patent Document 2.

<Connection method using bolts and nuts>
FIG. 23 is an exploded perspective view showing a connection method using bolts and nuts. That is, FIG. 23 is an exploded perspective view showing an electrode terminal, a current collector plate, and a pressing plate. FIG. 24 is a diagram illustrating a connection method using bolts and nuts. That is, FIG. 24 is a cross-sectional view showing an example of a connection structure of current collector plates.

As shown in FIG. 23, the electrode plate tabs 58 are joined to one end of the current collector plate 61 by a predetermined number, for example, by ultrasonic welding or laser welding. And the terminal base portion 51 ′ disposed in the battery lid. The current collecting plate 61 can be made of a conductive metal such as aluminum, titanium, nickel, or copper. Moreover, as long as it has high electroconductivity equivalent to a metal, the board made from other materials, such as resin, may be sufficient. Both the current collecting plate 61 and the pressing plate 63 are fixed to a terminal base portion 51 ′ having one or more through holes 59 and one or more non-through holes 60 that are screw holes. The current collecting plate 61 and the pressing plate 63 are formed with holes at the same intervals as through holes or screw holes formed in the terminal base portion 51 ′ so that they can be connected to the terminal base portion 51 ′. At this time, it is preferable that the distance between the through holes of the terminal base portion 51 ′ is uniform. By making the interval between the through holes uniform, the current collecting plates 61 are not distorted and connected, and the contact surfaces between the current collecting plates 61 and between the current collecting plates 61 and the terminal base portion 51 ′ are prevented from decreasing. Prevent high contact resistance. A through bolt 64 is inserted into the through hole from the holding plate side, the male screw portion of the through bolt protruding from the other end of the terminal base is fixed with a nut, and the screw hole is fitted from the holding plate side. Insert the screw bolt 62 to be fixed.

The number of positive electrode current collector plates 61a and negative electrode current collector plates 61b used varies depending on the number of positive electrode plates 57a and negative electrode plates 57b used. Therefore, it is important that the current collecting plates 61 have a thickness that does not increase the material resistance even when a plurality of the current collecting plates 61 are overlapped. Further, a cross-sectional area allowing current to flow between the welded electrode plate tab 58 and the terminal base portion 51 ′, and being sandwiched between the terminal base portion 51 ′ and the holding plate 63, a screw bolt 62, a through bolt 64 and a nut The strength which does not deform | transform and fracture | rupture by fastening by 65 combination is required.

The holding plate 63 is made of a conductive metal such as aluminum, titanium, nickel, copper, etc., and is preferably the same metal as the current collecting plate 61 in order to reduce material resistance. In the second embodiment, aluminum is used for the pressing plate of the positive terminal base portion 51'a, and copper is used for the pressing plate of the negative terminal base portion 51'b. The thickness of the pressing plate is preferably 3 mm or more. By having this thickness, the rigidity of the pressing plate member can be sufficiently secured and pressed uniformly.

FIG. 23 shows a method of fixing the current collecting plate 61, the pressing plate 63, and the terminal base portion 51 'at three locations. In this case, it is desirable that the positions of the holes are arranged so that symmetry can be seen, and that there are two through holes 59. The reason is that fixing by the through-hole 59 plays a role of uniformly pressing the current collector plate 61 and the terminal base portion 51 ′, so that the entire surface can be pressed in a balanced manner by arranging them symmetrically. Similarly, in the case where four or more holes are attached to one connection point of the current collector plate 61 and the positions of the holes are fixed so that symmetry can be seen, the through hole 59 and the number of screw holes are set. The same or more is preferable.

FIG. 24 shows a method of fixing the current collecting plate 61, the pressing plate 63, and the terminal base portion 51 'at two locations. Also in this case, the through-hole through which the through-bolt 64 penetrates and the screw hole to which the screw-in bolt 62 is fastened are respectively arranged at two positions symmetrical with respect to the center of gravity of the end surface of the terminal base portion 51 ′. It is desirable. As a result, the entire surface of the current collector plate 61 can be pressed against the terminal base portion 51 ′ with a good balance.

<Welding method by friction stir welding>
FIG. 25 is a diagram showing a joining method by friction stirring. That is, FIG. 25 is a view showing the vicinity of the welded portion where the tab is welded to the terminal base portion.

FIG. 25 shows a joining method by friction stir welding in which metal pieces or the like are hardly scattered during welding. Friction stir welding is a joining method in which a cylindrical tool having a protrusion at the tip is rotated, the base material is softened by frictional heat, and a plurality of members are integrated. FIG. 25 shows a case where the electrode plate tab 58, which is a positive electrode tab, for example, is friction stir welded to the terminal base portion 51 'of the positive electrode terminal, for example. A portion where the tab is welded to the terminal base portion is a welded portion 66. In this case, the conduction distance between the terminal 51 and the power generation element 56 becomes shorter than the method of connecting with the screw bolt 62 or the through bolt 64 using the current collector plate 61 and the holding plate 63 described above, and the welded portion. Since the current can also flow through 66, the resistance value can be further reduced.

By connecting the tab and the terminal using any one of the above connection methods, a plurality of positive electrode plates 57a and negative electrode plates 57b accommodated in the battery can 54 are respectively provided on the battery lid 55. Are electrically connected to the negative electrode terminal 51b.

<Configuration form of electrode group>
The electrode group is configured by alternately laminating positive and negative plates through separators. Specifically, the following three types of electrode groups A, B, and C were prepared.

<Electrode group A>
One end face and the other end face in the stacking direction of the positive electrode plate and the negative electrode plate are both configured by the negative electrode plate 57b.

<Electrode group B>
One end surface and the other end surface in the stacking direction are both configured by the positive electrode plate 57a.

<Electrode group C>
One end face in the stacking direction is constituted by a positive electrode plate 57a, and the other end face is constituted by a negative electrode plate 57b. In any of the electrode groups A, B, and C, the plurality of positive electrode tabs and negative electrode tabs are configured in the same direction. In the following examples, the electrode groups A, B, and C were combined, and a connection method using bolts and nuts and a connection method using friction stir welding were performed.

<Example of Embodiment 2>
Hereinafter, examples of the lithium ion battery according to the second embodiment will be described.

The lithium ion battery of the example of the second embodiment was manufactured in the same manner as the lithium ion battery described in the second embodiment. More specifically, lithium hexafluorophosphate (LiPF ₆ ) was used as a mixed solvent of ethylene carbonate and dimethyl carbonate as an electrolytic solution, and a polyethylene porous material was used as a separator. In addition, a battery was manufactured by applying the second embodiment described above.

<Example 5>
A lithium ion battery of Example 5 was produced. FIG. 26 is an explanatory diagram of the fifth embodiment, and shows an electrode group of the lithium ion battery of the fifth embodiment.

As shown in FIG. 26, in Example 5, four electrode groups were prepared using 200 positive plates and 204 negative plates. That is, one set includes 50 positive plates and 51 negative plates. In Example 5, the power generation element 56 was manufactured using four configurations of the electrode group A. Thereafter, the current collector plate 61 to which the electrode plate tab was welded and the terminal base portion 51 ′ were welded by using the above-described fixing method using bolts and nuts. In this embodiment, four electrode groups are produced. However, any number of electrode groups may be produced as long as the electrode groups of this embodiment are arranged. By using one type of arrangement of electrode groups, it can be expected to increase the efficiency of the electrode group manufacturing process. In the assembling process, when the electrode group is inserted into the battery can 54, the arrangement in which the positive electrodes face each other does not occur. In addition, the outermost surface of the electrode group adjacent to the battery can is necessarily the negative electrode surface, and the negative electrode plate alone is not involved in the ionic reaction, and therefore does not affect the quality even when touched during work. In particular, the configuration in which the electrode groups (A) are arranged next to each other increases safety because the positive electrode plates do not face each other even when the electrodes are displaced vertically or horizontally by vibration or the like after manufacturing. Is possible.

In addition, the secondary battery represented by such Example 5 is accommodated in the battery can 54, and each of the plurality of positive electrode plates 57a and each of the plurality of negative electrode plates 57b are in the direction in which the separators are interposed, that is, stacked. A plurality of electrode groups are alternately stacked in the direction. The plurality of electrode groups are arranged in the stacking direction. Negative electrode plates 57b are disposed on both end surfaces of each of the plurality of electrode groups in the stacking direction.

<Example 6>
A lithium ion battery of Example 6 was produced. FIG. 27 is an explanatory diagram of the sixth embodiment and shows a part of the electrode group of the lithium ion battery of the sixth embodiment.

In Example 6, five electrode groups were prepared using 200 positive electrode plates and 201 negative electrode plates. That is, an electrode group A consisting of 40 positive plates, 41 negative plates, and 40 electrode groups B consisting of 40 positive plates and 39 negative plates were prepared. In Example 6, three electrode groups A, two electrode groups B, and a total of five electrode groups were used, and A group and B group were alternately arranged to produce a power generation element. In FIG. 27, only two electrode groups A and one electrode group B are shown. In this example, five electrode groups were prepared, and then the current collector plate 61 to which the electrode plate tab was welded and the terminal base portion 51 ′ were welded by using the above-described fixing method using bolts and nuts. Any number of groups of electrodes may be formed as long as the electrodes are arranged in this embodiment. This is the number of tabs that can be welded to the current collector plate 61, and the number of each electrode group may vary as long as the contact resistance satisfies the target battery characteristics, but in order to make the resistance as uniform as possible. It is preferable that the number of electrode groups be equal. Since the positive plates 57a and the negative plates 57b are completely alternately arranged, the total number of the positive plates 57a and the negative plates 57b can be minimized.

In addition, the secondary battery represented by such Example 6 is accommodated in the battery can 54, and each of the plurality of positive electrode plates 57a and each of the plurality of negative electrode plates 57b is in a direction through the separator, that is, stacked. Three or more electrode groups are alternately stacked in the direction. The three or more electrode groups include two or more electrode groups (A) and one or more electrode groups (B), and are arranged in the stacking direction. Negative electrode plates 57b are respectively disposed on both end faces in the stacking direction of the electrode group (A). Positive electrode plates 57a are arranged on both end faces in the stacking direction of the electrode group (B). Electrode groups (A) are respectively arranged at positions on both ends of the array of electrode groups. Two or more electrode groups (B) such that only one electrode group (B) is arranged at positions other than both ends of the arrangement of the electrode groups, or the electrode groups (B) are not adjacent to each other; One or more electrode groups (A) are arranged.

<Example 7>
A lithium ion battery of Example 7 was produced. FIG. 28 is an explanatory diagram of the seventh embodiment and shows an electrode group of the lithium ion battery of the seventh embodiment.

As shown in FIG. 28, in Example 7, 200 positive plates and 202 negative plates were used. In Example 7, two electrode groups A, two electrode groups C, and a total of four electrode groups were used. The electrode group C was disposed such that the end face facing the battery can was the negative electrode plate 57b and the face facing the electrode group A was the positive electrode plate 57a. As shown in FIG. 28, the electrode group A was arranged so as to be sandwiched between the electrode groups C. Thereafter, the electrode plate tab 58 and the terminal base portion 51 'were fixed by the fixing method using the bolts and nuts described above. In this embodiment, the electrode group is divided into four groups. However, if the electrode groups of this embodiment are arranged, the A group can be increased, but the C group is in the direction in which the battery can side and the electrode plate surface are in contact with each other. On the other hand, it will be located at both ends of the array of electrode groups.

<Example 8>
A lithium ion battery of Example 8 was produced. In Example 8, four electrode groups were prepared using 200 positive plates and 204 negative plates. One electrode group has 50 positive plates and 51 negative plates. In Example 8, the power generation element 56 was manufactured using four configurations of the electrode group A. Thereafter, the electrode plate tab 58 and the terminal base portion 51 ′ were welded by the above-described welding method by friction stirring. In the present embodiment, the electrode group is divided into four groups. However, the electrode group may be divided into any number of groups as long as the electrode groups of the present embodiment are arranged.

<Comparative Example 5>
On the other hand, a lithium ion battery of Comparative Example 5 was produced. In Comparative Example 5, one positive electrode plate was used, 200 negative electrode plates were used, 201 negative electrode plates were used, and a total of 401 positive and negative electrode plates were used to produce one electrode group. Thereafter, the electrode plate tab 58 and the terminal base portion 51 ′ were fixed by a fixing method using bolts and nuts.

Hereafter, the elements compared with the present invention are listed. That is, Table 3 below shows the number of positive electrode plates, the number of negative electrode plates, and the number of electrode groups in Examples 5 to 8 and Comparative Example 5.

For Examples 5 to 7, the connection method using the above-described bolts and nuts was performed, and the contact resistance of the part where the electrode plate tab 58 and the terminal base part 51 ′ were connected via the current collector plate 61 was measured. Measured the contact resistance of the portion where the electrode plate tab 58 and the terminal base portion 51 'were connected using friction stir welding. For Comparative Example 5, the contact resistance when the positive electrode tab 58a and the negative electrode tab 58b were combined together and fixed with bolts was measured. The results are shown in Table 4.

In Table 4, a contact resistance of less than 0.1 mΩ is indicated by “◎”, 0.1-1 mΩ is indicated by “◯”, and 1 mΩ or more is indicated by “Δ”. As in the fifth to seventh embodiments, the positive terminal base 51′a or the negative terminal base 51′b is fixed to the positive terminal base 51′a or the negative terminal base 51′b by using a combination of the screw bolt 62, the through bolt 64 and the nut 65. Thus, it is possible to reduce the contact resistance as compared with Comparative Example 5. In Example 8, the positive electrode tab 58a or the negative electrode tab 58b is directly welded to the positive electrode terminal base part 51′a or the negative electrode terminal base part 51′b, so that the contact resistance can be greatly reduced as compared with Comparative Example 5. It is.

Next, the working time required from the electrode stacking work of Examples 5 to 8 to the fixing to the terminal base body was examined. As a study, three lithium ion batteries were produced corresponding to each of the examples and comparative examples, and the average working time was compared. The results are shown in Table 5.

In Table 5, “◯” is marked for those having a short average working time for Comparative Example 5. In the case of Comparative Example 5, since the number of electrodes is large, it is difficult to fix all the electrodes to the terminal base body by a single welding, and it takes a lot of time to adjust the opposing electrodes to shift. It cost. On the other hand, in the case of Examples 5 to 8, it was divided into electrode groups and fixed using a combination of screw bolts 62, through bolts 64 and nuts 65 using current collector plate 61, or friction stir welding was used. As a result, the average work time can be shortened.

In Examples 5 to 7, the positive plate 57a and the negative plate 57b through the current collector plate 51 are passed through the through bolts 64 through the through holes 59 of the positive terminal base portion 51′a and the negative terminal base portion 51′b, The screw bolt 62 fixed to the non-through hole 60 in which the thread is carved is fixed at three points. Further, in Comparative Example 6, the positive electrode plate 57a and the negative electrode plate 57b are fixed at two points including only through bolts 64 through the through holes 59. Examples 5 to 7 and Comparative Example 6 were compared from the viewpoint of contact resistance. The results are shown in Table 6. In Table 6, it is indicated by Δ when the contact resistance is 1 mΩ or more, and ○ when it is 1 mΩ or less.

Compared to Comparative Example 6, the lithium ion batteries manufactured in Examples 5 to 7 have more uniform electric conduction paths because the current collector plates are in uniform contact with each other and are fixed to the non-through holes 60 with through bolts 64. As a result, the contact resistance can be reduced.

<Main features and effects of the present embodiment>
In the secondary battery according to the second embodiment, since the arrangement in which the positive electrode plates face each other does not occur, the safety is improved. In addition, the configuration in which the electrode groups (A) are arranged next to each other further enhances safety because the positive electrode plates do not face each other even when the electrodes are displaced vertically or horizontally by vibration during use of the battery. It becomes possible.

By connecting the current collector plate to the current collector plate, and using the connection method that uses the current collector plate and terminal base part in combination with through bolts, nuts, and screw bolts, there is no need to weld and fix bolts at the same location. The contact resistance can be kept small, and a large current discharge is possible. This is because the through bolt exhibits a function of preventing loosening due to heat from external vibrations and charging / discharging, and the screwed bolt exhibits an effect of increasing the conductivity between the current collector plate and the terminal. Furthermore, since welding is used before the current collector plate is fixed to the terminal, there is little possibility that the metal piece of the terminal is mixed.

By dividing the electrode group and using a method in which the electrode plate tab and the terminal are directly joined by friction stir welding, the conduction distance is shortened, so that the resistance component can be further reduced. Further, since friction stir welding is a method in which the metal at the joint is flowed and fixed by frictional heat, the scattering of metal pieces can be greatly reduced. In this way, it is possible to provide a secondary battery having both high safety and high reliability.

As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments and examples. However, the present invention is not limited to the above-described embodiments and examples, and does not depart from the gist of the invention. Various changes can be made.

For example, the above embodiment is applicable to various secondary batteries other than lithium ion batteries.

In the above examples and comparative examples, the evaluation was performed without using other safety devices such as a cell controller having a current interruption mechanism in the safety evaluation, but the actual product includes the cell controller. It goes without saying that further safety measures are taken and safety is enhanced in a double and triple manner.

The present invention is effective when applied to a lithium ion battery.

DESCRIPTION OF SYMBOLS 1 ... Battery case, 1a ... Cover, 2 ... Injection port, 3 ... Gas discharge valve, 4 ... Electrode terminal, 4a ... Positive electrode terminal, 4b ... Negative electrode terminal, 6 ... Electrode plate, 6a ... Positive electrode plate, 6b ... Negative electrode plate , 8 ... Separator, 9 ... Electrode group, 10 (10a, 10b) ... Current collector tab, 11 ... Electrode bundle, 12 ... Electrode bundle, 13 (13a, 13b) ... Current collector plate, 14 ... Small electrode group, 15 (15a, 15b) ... presser plate, 16 (16a, 16b) ... through hole, 17 (17a, 17b) ... screw hole, 18 (18a, 18b) ... through bolt, 19 (19a, 19b) ... screwed bolt, 20 ... Nut, 41 ... End face, 42 ... End face, 51 (51a, 51b) ... Terminal, 51 '(51'a, 51'b) ... Terminal base part, 52 ... Injection port, 53 ... Cleavage valve, 54 ... Battery Can, 55 ... Battery cover, 56 ... Power generation element, 57 (57a, 57b) ... Electrode plate, 58 ... Electrode plate 58a ... positive electrode tab, 58b ... negative electrode tab, 59 ... through hole, 60 ... non-through hole, 61 (61a, 61b) ... current collector plate, 62 ... screw bolt, 63 ... presser plate, 64 ... through bolt, 65 ... Nut, 66 ... welded part, 161 (161a, 161b) ... through hole, 162 (162a, 162b) ... through hole, 171 (171a, 171b) ... through hole, 172 (172a, 172b) ... through hole, 181 ... Shaft part, 182 ... head part, 191 ... shaft part, 192 ... head part, BD ... joint part

Claims

A battery container;
A first electrode terminal provided in the battery case and having a first polarity;
A second electrode terminal provided in the battery container and having a second polarity opposite to the first polarity;
A plurality of first electrode plates respectively provided in the battery container and having the first polarity;
A plurality of second electrode plates each provided in the battery container and having the second polarity;
A first current collector connected to each of the plurality of first electrode plates;
A first mounting plate attached to the first electrode terminal across the first current collector plate;
A first screw member, a first nut member, and a second screw member attaching the first mounting plate to the first electrode terminal;
Have
Each of the plurality of first electrode plates and each of the plurality of second electrode plates are alternately stacked via separators,
The first electrode terminal has a first through hole for penetrating the first screw member and a first screw hole for fastening the second screw member,
The first mounting plate is formed with a first screw hole for penetrating the first screw member and a second screw hole for penetrating the second screw member,
The first current collector plate is formed with a third screw hole for penetrating the first screw member and a fourth screw hole for penetrating the second screw member,
The first screw member penetrating the first screw hole, the third screw hole, and the first through hole is fastened to the first nut member, and the second screw hole The second screw member penetrating the fourth screw hole is fastened to the first screw hole, so that the first mounting plate is connected to the first electrode terminal with the first current collector plate interposed therebetween. Is attached, and the first current collector plate is connected to the first electrode terminal.
The secondary battery according to claim 1,
Having a third screw member and a second nut member attaching the first mounting plate to the first electrode terminal;
The first electrode terminal is formed with a second through hole for penetrating the third screw member,
The first mounting plate is formed with a fifth screw hole for allowing the third screw member to pass therethrough,
The first current collector plate is formed with a sixth screw hole for allowing the third screw member to pass therethrough,
When the third screw member penetrating the fifth screw hole, the sixth screw hole, and the second through hole is fastened to the second nut member, the first current collector plate A secondary battery in which the first attachment plate is attached to the first electrode terminal with the first electrode terminal interposed therebetween, and the first current collector plate is connected to the first electrode terminal.
The secondary battery according to claim 2,
The first screw hole is formed at the center of the first end surface of the first electrode terminal,
The first through hole is formed in a first portion of the first end face located on the first side of the central portion,
The second through hole is a secondary battery formed in a second portion of the first end face located on the opposite side of the central portion from the first side.
The secondary battery according to claim 2,
The first screw hole is formed at the center of gravity of the first end surface of the first electrode terminal,
The first through hole is formed at a first position within the first end face, away from the center of gravity of the first end face,
The said 2nd through-hole is a secondary battery currently formed in the 2nd position which is a position symmetrical with the said 1st position centering | focusing on the said gravity center within the said 1st end surface.
The secondary battery according to claim 1,
The first through hole is formed in a first portion of the first end surface of the first electrode terminal that is located on the first side of the center portion of the first end surface;
The said 1st screw hole is a secondary battery currently formed in the 2nd part located in the said 1st end surface on the opposite side to the said 1st side of the said center part.
The secondary battery according to claim 1,
The first through hole is formed in a first position away from the center of gravity of the first end surface within the first end surface of the first electrode terminal.
The said 1st screw hole is a secondary battery currently formed in the 2nd position which is a position symmetrical with the said 1st position centering | focusing on the said gravity center within the said 1st end surface.
The secondary battery according to claim 1,
The first nut member is a secondary battery made of a double nut.
The secondary battery according to claim 1,
A plurality of first current collecting tabs provided at respective end portions of the plurality of first electrode plates;
The first current collecting plate is a secondary battery connected to each of the plurality of first current collecting tabs.
The secondary battery according to claim 1,
A second current collector connected to each of the plurality of second electrode plates;
A second mounting plate attached to the second electrode terminal across the second current collector plate;
A fourth screw member, a third nut member and a fifth screw member attaching the second mounting plate to the second electrode terminal;
Have
In the second electrode terminal, a third through hole for penetrating the fourth screw member and a second screw hole for fastening the fifth screw member are formed,
The second mounting plate is formed with a seventh screw hole for penetrating the fourth screw member and an eighth screw hole for penetrating the fifth screw member,
The second current collector plate has a ninth screw hole for penetrating the fourth screw member and a tenth screw hole for penetrating the fifth screw member,
The fourth screw member penetrating the seventh screw hole, the ninth screw hole, and the third through hole is fastened to the third nut member, and the eighth screw hole The fifth screw member penetrating the tenth screw hole is fastened to the second screw hole, so that the second mounting plate is connected to the second electrode terminal with the second current collector plate interposed therebetween. Is attached, and the second current collector plate is connected to the second electrode terminal.
A secondary battery that is housed in a battery can and includes three or more electrode groups in which each of a plurality of positive electrode plates and each of a plurality of negative electrode plates are alternately stacked in a first direction via a separator,
The three or more electrode groups include two or more electrode groups (A) and one or more electrode groups (B), and are arranged in the first direction,
The negative plates are respectively disposed on both end faces in the first direction of the electrode group (A),
The positive plates are respectively disposed on both end faces in the first direction of the electrode group (B),
The electrode groups (A) are respectively disposed at positions at both ends of the arrangement of the electrode groups,
Only one electrode group (B) is disposed at a position other than both ends of the array of the electrode groups, or two or more electrodes so that the electrode groups (B) are not adjacent to each other. A secondary battery in which a group (B) and one or more electrode groups (A) are arranged.
A secondary battery that is housed in a battery can and includes a plurality of electrode groups in which each of a plurality of positive electrode plates and each of a plurality of negative electrode plates are alternately stacked in a first direction via a separator,
The plurality of electrode groups are arranged in the first direction,
A secondary battery in which the negative electrode plate is disposed on each end face in the first direction of each of the plurality of electrode groups.
A positive and negative electrode plate laminated via a separator has an electrode tab at each end, and an electrode group in which a predetermined plurality of positive and negative electrode plates are alternately laminated via a separator includes a plurality of the electrode groups. Is a secondary battery housed in a battery can,
The electrode group includes an electrode group (A) in which both electrode plates positioned on both end faces in the stacking direction of the electrode group are negative plates, and an electrode plate positioned on one end face in the stacking direction of the electrode groups is a positive electrode plate on the other end face. The electrode group in which the electrode plate located is a negative electrode plate (C),
The electrode group (C) is disposed so that the negative electrode plate side of the end surface in the stacking direction faces the inner wall surface of the battery can,
The electrode group (C) or the electrode group (A) and the electrode group (C) are arranged so that the opposing surfaces of the adjacent electrode groups do not become a positive electrode plate except for the position facing the inner wall surface of the battery can. Secondary battery characterized by being made.
The electrode tabs of the same polarity are joined to the positive and negative current collector plates for each electrode group, and the current collector plates of the same polarity are fastened to the positive and negative terminal base portions by bolts together with the holding plates. The secondary battery according to any one of claims 10 to 12.
The secondary battery according to any one of claims 10 to 12, wherein electrode tabs of the same polarity of each electrode group are joined to positive and negative terminal base parts by friction stir welding.
The secondary battery according to any one of claims 10 to 12, wherein the total number of positive and negative electrode plates is at least 400.