JP2004200118A - Battery and battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery and a battery pack wherein assembly man-hour and number of parts are few and cost reduction is realized, and mass producibility is superior, and a high output is obtained by reducing the internal resistance per unit electric cell. <P>SOLUTION: This battery has electrode plate groups in which a core material of a positive electrode plate is exposed on one end and the core material of a negative electrode plate is respectively exposed on another end, an encapsulating case of the bottomed cylindrical shape which becomes an electrode terminal because the bottom face is connected to either one end face of the electrode plate groups, a positive terminal connected to another end face of the electrode plate group, and a cap body fixed to the encapsulating case. The negative electrode terminal joined to the bottom part of the encapsulating case of other battery is coupled to the positive electrode terminal. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a battery, and more particularly to a battery suitable for forming an assembled battery in which one end and the other end of a plurality of batteries are sequentially connected, and an assembled battery thereof.
[0002]
[Prior art]
In recent years, the expectations for electric vehicles and hybrid vehicles have increased due to global environmental problems. For secondary batteries as power sources, there has been a demand for smaller and lighter batteries as well as higher capacity and higher output. An assembled battery connected in series is used.
[0003]
A configuration of a lithium ion battery, which is an example of the secondary battery, will be described with reference to FIG. Reference numeral 21 denotes a spirally wound positive electrode plate 22 having a positive electrode material 22a applied to a positive electrode current collector 22b and a negative electrode plate 23 having a negative electrode material 23a applied to a negative electrode current collector 23b via a separator 24. Electrode group. Reference numerals 25 and 26 denote a positive electrode current collector and a negative electrode current collector joined to both end surfaces of the electrode plate group 21. A positive electrode tab 25a is welded to the positive electrode current collector plate 25.
[0004]
The electrode plate group 21 is housed in an outer case 27 together with the electrolytic solution, and the negative electrode current collector 26 is resistance-welded to the inner bottom surface of the outer case 27, so that the outer case 27 serves as a negative electrode terminal of the battery. Reference numeral 28 denotes a lid having a hole 28a at the center, into which an O-ring 29, an explosion-proof valve body 30, a spacer 31, and a cap 32 are inserted, and then a caulking portion 28b on the outer periphery is integrally formed. The explosion-proof valve body 30 is a thin film made of aluminum foil, and is configured to break through the hole 31a of the spacer 31 to discharge gas inside the battery to the outside when the battery internal pressure rises above a predetermined pressure. I have. The positive electrode tab 25a is welded to the lid 28, and the current from the electrode plate group 21 is supplied to the cap 32 from the caulked portion 28b of the lid 28, and the cap 32 becomes a positive electrode terminal of the battery. Reference numeral 27a denotes a groove for positioning the lid 28, which is formed by plastically processing the outer case 27. A gasket 33 is interposed between the outer case 27 and the lid 28. The gasket 33 insulates the two and has a sealing function by caulking the opening 27b of the outer case 27 so as to sandwich the lid 28. are doing.
[0005]
Further, the connecting body 35 is formed of a stepped bowl-shaped press-formed product having a bottomed small-diameter cylindrical portion 36, a step portion 37 and a large-diameter cylindrical portion 38. A hole 39 through which a connection protrusion of the cap 32 penetrates is formed on the bottom surface, and is abutted on the cap 32, and is resistance-welded to the cap 32 at a welding point 40 by a plurality of projections formed on the bottom surface. . The bottom of the outer case 27 is inserted and fitted into the large-diameter cylindrical portion 38, is held in contact with the step portion 37, and is welded to the outer case 27 by a plurality of projections formed on the large-diameter cylindrical portion 38. At 41, resistance welding is performed.
[0006]
[Patent Document 1]
JP 10-106533 A
[Problems to be solved by the invention]
However, in the above-described configuration of the conventional battery and the assembled battery, since the connection between the batteries is performed by using the connecting body 35 which is a separate component from the battery lid 28, after the assembled battery is assembled, the connection is performed. A step of assembling the body 35 and connecting another battery is required, which causes a problem that the number of parts and the number of assembling steps are increased, cost is increased, and mass productivity is deteriorated.
[0008]
In addition, the current path between the batteries is transferred from the electrode group 21 to the electrode group 21 through the positive electrode current collector 25, the positive electrode tab 25 a, the lid 28, the cap 32, the connector 35, the outer case 27, and the negative electrode current collector 26. The resistance value increases because the current path between the cells is long and there are many connections between them, and the internal resistance per cell increases, prolonging the battery life and increasing the output There is a problem that it becomes a major obstacle to the above.
[0009]
In view of the above conventional problems, the present invention provides a battery and a battery pack that have a small number of assembly steps and a small number of parts, can reduce costs, are excellent in mass productivity, and have a high output by reducing the internal resistance per cell. The purpose is to provide.
[0010]
[Means for Solving the Problems]
The present invention is an electrode plate group in which a positive electrode plate and a negative electrode plate are configured with a separator interposed therebetween, and a core material of the positive electrode plate is exposed on one end surface, and a core material of the negative electrode plate is exposed on the other end surface, A current collector plate connected to any one end surface of the electrode group, and a bottomed cylindrical outer case in which the electrode plate group is inserted and the current collector plate is connected to the bottom surface and serves as one electrode terminal, An electrolytic solution impregnated inside the electrode plate group, the other electrode terminal connected to the other end face of the electrode plate group, and a lid fixed to an outer case. The battery is provided with explosion-proof means for releasing internal gas in accordance with the above, sealing means for sealing the electrode terminal and the lid, and fixing means for fixing the electrode terminal and the lid.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The battery of the present invention is configured such that a positive electrode plate and a negative electrode plate are formed with a separator interposed therebetween, and an electrode plate group in which a core material of the positive electrode plate is exposed on one end surface and a core material of the negative electrode plate is exposed on the other end surface. A current collector plate connected to one end face of the electrode plate group, and a bottomed cylindrical outer case into which the electrode plate group is inserted and the current collector plate is connected to the bottom surface to become one electrode terminal And an electrolytic solution impregnated inside the electrode plate group, the other electrode terminal connected to the other end face of the electrode plate group, and a lid fixed to the outer case. Explosion-proof means for releasing the internal gas in response to the rise of the gas, sealing means for sealing the electrode terminal and the lid, and fixing means for fixing the electrode terminal and the lid. Is directly connected, eliminating the need for a separate positive electrode tab that was previously used to connect inside the battery. Assembling steps and the number of parts is reduced, excellent in mass production with attained cost reduction, also the internal resistance decreased per unit cell, a high output of a battery with a reduced internal resistance.
[0012]
Also, since the electrode terminal welded to the bottomed cylindrical outer case and the electrode terminal directly connected to the other end face of the electrode plate group have a threaded portion, one of the threaded portions is a male screw and the other is a male thread. The connection can be made by using a female screw for the threaded portion, and a plurality of batteries can be easily connected.
[0013]
Further, a torque wrench or the like can be used by providing a D-cut around the outer periphery of the electrode terminal welded to the bottomed cylindrical outer case and the outer periphery of the electrode terminal directly connected to the end face of the electrode plate group. The connection can be stably fastened with a predetermined load.
[0014]
Note that the D cut is obtained by removing the outer peripheral portion of the cylinder at a fixed distance in parallel with the center line of the circle.
[0015]
Also, in a plurality of batteries, the outer case bottom of one battery is fitted to the connection part of the electrode terminal of the other battery, and the fitting part is welded and connected to each other, so that the current path between the batteries is formed. Is short and the number of connection points is small, so that a high-output battery pack having low internal resistance per unit cell can be obtained.
[0016]
In addition, the workability is improved by connecting a plurality of batteries to each other by screw-fixing the electrode terminals having a threaded portion welded to the bottom of the outer case of one battery to the electrode terminals of the other battery. A highly reliable connection can be realized, and a high-output battery pack having a small internal resistance of the battery connection portion can be obtained.
[0017]
Hereinafter, an embodiment in which the battery and the battery pack of the present invention are applied to a lithium ion battery will be described with reference to FIGS.
[0018]
In FIG. 1, reference numeral 1 denotes a unit cell, which is configured such that an electrode plate group 3 is accommodated in an outer case 2 together with an electrolytic solution (polyethylene carbonate (PC) solution) and sealed with a lid 4. The outer case 2 is formed of a bottomed cylindrical deep drawn product made of a stainless steel plate having an electrolytic solution property.
[0019]
Note that the outer case only needs to have electrolytic solution resistance, and other than the above, a nickel plated plate, an aluminum plate, or the like can be used.
[0020]
The electrode plate group 3 is formed by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween, and a core material of the positive electrode plate is provided on the upper end surface, and a core material of the negative electrode plate is provided on the lower end surface. Is exposed without being applied.
[0021]
The positive electrode plate is configured by applying a positive electrode material containing lithium cobalt oxide as a positive electrode active material and polyvinylidene fluoride (PVDF) as a binder on both surfaces of a core material made of an aluminum foil.
[0022]
As the positive electrode active material, in addition to lithium cobaltate, a lithium-containing transition metal composite oxide such as lithium nickelate and lithium manganate (including a case where other elements are added) is used.
[0023]
The negative electrode plate is formed by applying a negative electrode material containing (graphite) as a negative electrode active material and PVDF as a binder on both surfaces of a core material made of copper foil.
[0024]
As the negative electrode active material, other than graphite, carbonaceous materials such as petroleum cokes and carbon fibers and alloys are used.
[0025]
Although FIG. 1 shows an example in which the electrode plate group 3 wound around the cylindrical outer case 2 is accommodated, a pole in which a flat positive electrode plate and a negative electrode plate are laminated on a rectangular parallelepiped outer case via a separator is shown. A board group may be accommodated.
[0026]
Examples of the electrolyte include lithium salts such as lithium hexafluorophosphate (LiPF ₆ ) and lithium borofluoride (LiBF ₄ ) as solutes, ethylene carbonate (EC), propylene carbonate (PC), and vinylene carbonate (VC) as solvents. A non-aqueous solvent such as gamma-butyrolactone (GBL), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) is used, and a solute dissolved in this solvent is used.
[0027]
As shown in FIG. 4A, the opening 14 of the outer case 2 is preliminarily processed to increase the outer diameter, and the outer diameter of the case 2 is partially increased. Are connected by projection resistance welding via a convex portion 6 provided on the negative electrode terminal 5.
[0028]
A negative electrode current collector plate 13 is welded to the negative electrode core material exposed at the lower end face of the electrode plate group 3, and a negative electrode current collector plate 13 is further exposed to the positive electrode core material exposed at the upper end face of the electrode group 3. The positive electrode terminal 8 having a current collecting function is welded.
[0029]
After accommodating the electrode plate group 3 in the outer case 2 in this state, the center of the negative electrode current collector 13 and the bottom center 7 of the outer case 2 are laser-welded from the outside of the outer case 2. The welding of the positive electrode core material exposed on the end face of the electrode plate group 3 and the positive electrode terminal 8 having a current collecting function is performed by projecting protrusions 8a extending from the center at a plurality of positions in the circumferential direction of the positive electrode terminal 8, By pressing the positive electrode terminal 8 against the end face of the electrode plate group 3, the projection 8a is welded in a state of being in close contact with the positive electrode core material.
[0030]
Further, welding of the negative electrode core material and the negative electrode current collector plate 13 exposed on the other end surface of the electrode plate group 3 forms protrusions 13 a extending from the central portion at a plurality of circumferential positions of the negative electrode current collector plate 13. By pressing the negative electrode current collector plate 13 against the end face of the electrode plate group 3, the projection 13a is welded in a state of being in close contact with the negative electrode core material.
[0031]
In addition, as a welding method, electron beam welding etc. other than laser welding are mentioned.
[0032]
As shown in FIG. 2, the positive electrode terminal 8 has a recess 8d in the center of the terminal where an O-ring 9 as a sealing means is provided. In addition, a square ring, a D ring, and an X ring can be used as the sealing means.
[0033]
As shown in FIG. 1, a safety valve 11 that releases internal gas in response to an increase in internal pressure is fixed to the lid 4 by caulking, and an E-ring 10 that fixes the lid 4 is inserted into the positive electrode terminal 8. It has a groove 8b for fixing.
[0034]
A gasket 12 having electrical insulation and sealing properties is arranged on the outer periphery of the lid 4.
[0035]
In manufacturing the battery 1 having the above-described configuration, the outer case 2 is partially pre-processed to increase the outer diameter in the opening 14, and further, the negative terminal 5 is welded to the outside of the bottom surface of the outer case 2. ing.
[0036]
The electrode group 3 in which the positive electrode terminal 8 and the negative electrode current collector 13 are welded to each other is inserted into the outer case 2 and accommodated therein. As shown in FIG. After installation, the bottom central part 7 of the exterior case 2 is joined by welding.
[0037]
Then, the positive electrode terminal is placed on the upper side, and a predetermined amount of electrolytic solution is injected from the opening of the outer case 2 to impregnate the electrode plate group 3, and then the sealing means 9 is placed in the recess 8d.
[0038]
After fitting the gasket 12 into the opening 14 of the outer case 2, the cover 4 is inserted into the positive terminal 8, and the E-ring 10 is placed in the groove 8 b of the positive terminal 8 while applying a load to the cover 4. I do. After that, as shown in FIG. 4B, the end of the opening of the outer case 2 is deformed by a mold and caulked.
[0039]
Next, the battery is passed through a mold through an opening in which the outer diameter of the outer case 2 has been previously expanded, the outer diameter of the opening is reduced to the original outer diameter of the outer case 2, and the gasket 12 is compressed and deformed. The sealing performance is ensured, and the battery 1 is completed.
[0040]
A plurality of batteries 1 having the above configuration are connected in series to form a battery pack 16 as shown in FIG. When assembling the assembled battery 16, as shown in FIG. 5, the other positive electrode terminal is inserted and fitted into the negative electrode terminal which is resistance-welded to the bottom of the outer case 2 of one battery 1, and is laser-welded. I do.
[0041]
In addition, by providing screws on the negative electrode terminal and the positive electrode terminal and providing D-cuts on the outer periphery of the negative electrode terminal and the positive electrode terminal, more stable fastening can be achieved.
[0042]
According to the above embodiment, since the positive electrode terminal is directly connected to the electrode plate group 3, parts such as the positive electrode tab are not required, the number of assembling steps and the number of parts are reduced, the cost can be reduced, and the mass productivity is excellent. Also, the internal resistance per unit cell is reduced, and a high-output battery 1 with reduced internal resistance is obtained.
[0043]
Also, since the negative electrode terminal 5 having a screw portion welded to the outer case 2 and the positive terminal 8 directly connected to the other end face of the electrode plate group 3 have a screw portion, the battery and the battery Reliable connection can be made during connection.
[0044]
Further, by providing a D-cut on the outer periphery of the negative electrode terminal 5 and the positive electrode terminal 8, it is possible to realize connection with higher workability and higher reliability by using a torque wrench or the like.
[0045]
Further, when connecting the battery 1 and another battery, the negative electrode terminal 5 and the positive electrode terminal 8 are screw-fastened, so that only the torque management at the time of fastening is required, and furthermore, the assembled battery with high workability and high reliability is connected. Is obtained.
[0046]
It should be noted that, in addition to the positive electrode terminal 8 and the negative electrode terminal 5 which are screw-processed, the positive electrode terminal 8 is columnar and the negative electrode terminal 5 is formed in a hole shape. Is also good.
[0047]
In the above description, the positive electrode 8 is on the positive electrode side and the outer case 2 is on the negative electrode side. However, the positive and negative electrodes may be reversed, and the outer case 2 may be on the negative electrode side and the outer case 2 may be on the positive electrode side. In this case, the outer case 2 is made of aluminum or an aluminum alloy.
[0048]
Further, in the above embodiment, only the example in which the battery 1 is formed of a lithium ion battery has been described. However, the present invention can obtain the same function and effect by applying the present invention to a battery having another configuration such as a nickel hydride battery. it can.
[0049]
【The invention's effect】
According to the battery of the present invention, since the positive electrode terminal is directly connected to the electrode group as described above, parts such as the positive electrode tab are not required, the number of assembly steps and the number of parts are reduced, the cost can be reduced, and mass production can be achieved. The battery has excellent performance and the internal resistance per unit cell is reduced, so that a high-output battery with reduced internal resistance can be obtained.
[Brief description of the drawings]
1 is a sectional view of a battery according to an embodiment of the present invention; FIG. 2 is a perspective view of a positive electrode terminal of the battery of the embodiment; FIG. 3 is an exploded perspective view of the battery of the embodiment; FIG. 5B is a cross-sectional view of the outer case opening before the battery of the embodiment is sealed. FIG. 5B is a vertical cross-sectional view of the battery pack of the embodiment after the sealing of the battery of the embodiment. FIG. 6 is a longitudinal sectional view of a connecting portion in the battery pack to which the conventional battery is connected.
REFERENCE SIGNS LIST 1 Battery 2 Outer case 3 Electrode plate group 4 Lid 5 Negative terminal 8 Positive terminal 10 E-ring 11 Safety valve 12 Gasket 13 Negative current collecting plate 14 Expandable part 16 Battery pack

Claims (5)

A positive electrode plate and a negative electrode plate are opposed to each other with a separator interposed therebetween, and an electrode plate group in which a core material of the positive electrode plate is exposed on one end surface and a core material of the negative electrode plate is exposed on the other end surface, A current collector plate connected to one of the end faces, a bottomed cylindrical outer case into which the electrode group is inserted and the current collector plate is connected to the bottom surface to serve as one electrode terminal, and an inside of the electrode group. And an electrode terminal connected to the other end face of the electrode plate group, and a lid fixed to the outer case. A battery provided with explosion-proof means for releasing gas, sealing means for sealing the electrode terminal and the lid, and fixing means for fixing the electrode terminal and the lid. The battery according to claim 1, wherein one of the electrode terminals and the current collector plate are integrated. The battery according to claim 1, further comprising a threaded portion on the electrode terminal welded to the outside of the bottomed cylindrical outer case and the electrode terminal directly connected to the other end surface of the electrode plate group. The battery according to claim 3, wherein a D-cut is provided on the outer periphery of the electrode terminal welded to the bottomed cylindrical outer case and on the outer periphery of the electrode terminal directly connected to the end face of the electrode plate group. An assembled battery to which the battery according to claim 1 is connected.

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