JP5231089B2 - Sealed secondary battery - Google Patents

Description

  The present invention relates to a sealed secondary battery, and in particular, an electrode group in which a positive electrode plate and a negative electrode plate are wound around a shaft centered around a separator, and a current collecting member disposed to face an end surface of the electrode group, The present invention relates to a sealed secondary battery including an energizing member for connecting a current collecting member to an external terminal, a cylindrical battery container, and a battery lid for sealing the battery container.

  Lithium ion secondary batteries, which are one type of sealed secondary batteries, are used in various electrical devices as small consumer batteries, taking advantage of the high energy density. Further, for example, a large-sized secondary battery having a capacity of 3.0 Ah or more is attracting attention as a power source for a hybrid (electric) vehicle (HEV) or an electric vehicle (PEV).

  Among such large-sized secondary batteries, the HEV battery usually has an electrode group in which a positive and negative electrode plate is wound around a shaft core via a separator in a bottomed cylindrical battery container. The opening of the battery container is stepped (constricted), and the stepped opening is caulked and sealed with a battery lid via an electrically insulating gasket. The front end portions of the current collecting lead pieces led out from the positive and negative electrode plates constituting the electrode group are respectively joined to current collecting members made of aluminum (positive electrode) or copper (negative electrode). The current collecting member is electrically connected to the bottom surface of the battery lid and the inner bottom surface of the battery case via low current resistance current-carrying members such as aluminum and copper, and the battery lid and the battery case function as external terminals. It is a structure (see, for example, Patent Document 1).

  On the other hand, PEV batteries generally have a larger capacity than HEV batteries, and battery ring members arranged at both ends of the battery are provided with insulating ring components such as O-rings, and the current collecting member of the ring in which the insulating ring is enlarged. Thus, a structure is adopted in which the electrode group is sandwiched from both sides and the positive and negative battery lids are pressed together (see, for example, Patent Document 2).

JP 2006-073285 A JP 2002-260664 A (FIG. 1)

  In the large secondary battery, the mass of the electrode group itself becomes large. Therefore, in a secondary battery that is mounted on a vehicle and used in a large vibration or impact environment, the stress load applied to the current collecting member is increased due to vibration or shaking applied to the electrode group. Therefore, a high strength material is required. For this reason, if these functions are made compatible with the current collecting member, there is a problem in that the mass of the entire battery is increased.

  An object of the present invention is to provide a sealed secondary battery that suppresses the mass of a current collecting member and is excellent in vibration resistance.

In order to solve the above problems, the present invention provides an electrode group in which a positive electrode plate and a negative electrode plate are wound through a separator around an axis, and a current collecting member disposed to face an end surface of the electrode group, A current-carrying member for connecting the current-collecting member to an external terminal, a disk-shaped member made of an electrically insulating resin fixed to at least one end of the shaft core, and a side of the disk-shaped member opposite to the electrode group A ring-shaped member made of an electrically insulating resin that is fixed or integrated with the disk-shaped member, a cylindrical battery container that accommodates each of the members, and a battery lid that seals the battery container. In addition, at least a part of the peripheral surface of the disk-shaped member or the ring-shaped member is an inner peripheral surface of the battery container, and the end of the ring-shaped member opposite to the electrode group is the battery lid or the battery container. At least one of the bottom And has the has a convex portion is formed on the lower side of the disc-shaped member, the convex portion is fitted and fixed to said axis, said disc-shaped member and the ring-shaped member and is fitted Or are integrally formed .

In the present invention, a disk-shaped member made of an electrically insulating resin fixed to at least one end of the shaft core, and a disk-shaped member fixed to or integrated with the disk-shaped member on the side opposite to the electrode group of the disk-shaped member is electrically insulated. A ring-shaped member made of a functional resin, and at least a part of the peripheral surface of the disk-shaped member or the ring-shaped member is an inner peripheral surface of the battery container, and an end of the ring-shaped member opposite to the electrode group At least one of the battery lid and the bottom of the battery container is in contact. Further, a convex portion is formed on the lower side of the disc-shaped member, the convex portion is fitted and fixed to the shaft core, and the disc-shaped member and the ring-shaped member are fitted, or It is integrally formed. According to the present invention, at least a part of the peripheral surface of the disk-shaped member or the ring-shaped member is the inner peripheral surface of the battery container, and the end opposite to the electrode group of the ring-shaped member is the bottom of the battery lid or the battery container. And a convex portion is formed on the lower side of the disc-shaped member, the convex portion is fitted and fixed to the shaft core, and the disc-shaped member and the ring-shaped member are Are fitted or integrally formed, so that the shaft core is in contact with the inner peripheral surface of the battery case or the battery lid or the bottom of the battery case, the electrode group is supported, and the current collecting member has a large mass and high strength. Even if it does not use it, the secondary battery excellent in vibration resistance can be obtained.

In the present invention, the disk-shaped member, the ring-shaped member, and the shaft core may be integrally formed. Further, at least a part of the peripheral surface of the disk-shaped member or the ring-shaped member is in contact with the inner peripheral surface of the battery container, and the end of the ring-shaped member opposite to the electrode group is the bottom of the battery lid. It is preferable to contact directly or via a spacer member. Further, the disk-shaped member may be disposed above the disk-shaped current collecting member, and the current collecting member may be fitted and fixed to the shaft core. At this time, the tip of the lead piece led out from the positive electrode plate may be joined to the bottom of the current collecting member. To further reduce weight, the disc-shaped member is formed with a through-hole for lightening, conductible member may be are electrically connected to the battery lid via a through hole.

According to the present invention, at least a part of the peripheral surface of the disk-shaped member or the ring-shaped member is the inner peripheral surface of the battery container, and the end opposite to the electrode group of the ring-shaped member is the bottom of the battery lid or the battery container. And a convex portion is formed on the lower side of the disc-shaped member, the convex portion is fitted and fixed to the shaft core, and the disc-shaped member and the ring-shaped member are Are fitted or integrally formed, so that the shaft core is in contact with the inner peripheral surface of the battery case or the battery lid or the bottom of the battery case, the electrode group is supported, and the current collecting member has a large mass and high strength. Even if it does not use it, the effect that the secondary battery excellent in vibration resistance can be obtained can be acquired.

  Hereinafter, an embodiment in which the present invention is applied to a cylindrical lithium ion secondary battery for a hybrid vehicle will be described with reference to the drawings.

(Constitution)
<Positive electrode plate>
As shown in FIG. 1, the positive electrode plate 1 constituting the electrode group 5 is configured by applying the active material mixture substantially uniformly and uniformly on both surfaces of the positive electrode current collector. In order to produce such a positive electrode plate 1, for example, LiMn ₂ O ₄ which is a lithium transition metal complex oxide as a positive electrode active material, graphite powder as a main conductive material, and acetylene black as a secondary conductive material are bound. Polyvinylidene fluoride (PVDF) as an agent (binder) was mixed at a mass ratio of 85: 8: 2: 5, and a dispersion solvent N-methyl-2-pyrrolidone (NMP) was added and kneaded. Make a slurry. The prepared slurry is applied to both surfaces of an aluminum foil (positive electrode current collector) having a thickness of 20 μm, and an uncoated portion having a width of 8 mm is formed on one side in the longitudinal direction of the aluminum foil. By drying, pressing and cutting the positive electrode plate coated with the slurry, a strip-like positive electrode plate having a width of 90 mm is obtained. In addition, a positive electrode lead piece (notch remaining part) is formed by notching an uncoated part in a comb shape.

<Negative electrode plate>
On the other hand, the negative electrode plate 2 is configured by applying the active material mixture substantially uniformly and uniformly on both surfaces of the negative electrode current collector. In order to produce such a negative electrode plate 2, for example, 92 parts by mass of graphitizable carbon powder as a negative electrode active material is added with 8 parts by mass of PVDF as a binder, and NMP as a dispersion solvent is added thereto. A kneaded slurry is prepared. The produced slurry is applied to both surfaces of a rolled copper foil (negative electrode current collector) having a thickness of 10 μm, and an uncoated portion having a width of 5 mm is formed on one side in the longitudinal direction of the rolled copper foil. The strip-shaped negative electrode plate having a width of 91 mm is obtained by drying, pressing, and cutting the negative electrode plate coated with the slurry. The uncoated portion is cut into a comb shape to form a negative electrode lead piece (notch remaining portion).

<Plate group>
The positive electrode plate 1 and the negative electrode plate 2 are made of polypropylene containing 30% glass fiber and hollow cylindrical shape through a separator 3 made of porous polyethylene having a width of 94 mm and a thickness of 40 μm so that the both plates are not in direct contact with each other. A group of electrodes 5 is formed by winding the electrode core 5 in a spiral shape. The positive electrode lead piece and the negative electrode lead piece described above are arranged on opposite sides of the electrode group 5, and protrude 4 mm from the end of the separator 3. The electrode group 5 is set to an inner diameter of 9 mm and an outer diameter of 38 ± 0.1 mm by adjusting the lengths of the positive electrode plate 1, the negative electrode plate 2 and the separator 3. In order to prevent unwinding, the winding end portion of the winding group 5 is fixed by sticking an adhesive tape in which a base material is polyimide and an adhesive made of hexamethacrylate is applied on one side thereof. ing. The electrode group 5 is housed in the center of a bottomed cylindrical battery case 11 made of steel plated with nickel. The battery container 11 has an outer diameter of 40 mm and an inner diameter of 39 mm.

  The outer periphery of the electrode group 5 is provided with an insulation coating for ensuring insulation from the inner peripheral surface of the battery case 11 over the entire periphery. For the insulation coating, for example, an adhesive tape in which a mexamethacrylate adhesive is applied to one side of a polyimide base material is used. The adhesive tape is wound one or more times around the outer peripheral surface of the electrode group 5.

<Battery structure>
A hat portion of a negative electrode lead plate 12 made of copper and having a substantially inverted hat shape is welded to the inner bottom surface of the battery container 11 for electrical conduction to the negative electrode battery container 11. On the upper part of the negative electrode lead plate 12, a copper negative electrode current collecting ring 7 for collecting the electric potential from the negative electrode plate 2 is disposed so as to face the lower end surface of the electrode group 5. The inner peripheral side of the negative electrode current collecting ring 7 is fitted to the shaft core 4 at the lower end portion of the shaft core 4. Further, the outer edge portion (flange portion) of the negative electrode current collecting ring 7 is in contact with the upper surface and the rising portion of the hat peripheral edge portion (flange portion) of the negative electrode lead plate 12, and the falling end surface (outer peripheral portion) of the negative electrode current collecting ring 7 The tip is also in contact with the negative electrode lead plate 12. The tip of the negative electrode lead piece led out from the negative electrode plate 2 is collected and welded to the falling part (outer peripheral part) of the negative electrode current collecting ring 7. Therefore, in this embodiment, the battery container 11 functions as a negative electrode external terminal.

  On the other hand, at the upper end portion of the shaft core 4, an aluminum disc-shaped positive electrode current collector plate 6 for collecting the electric potential from the positive electrode plate 1 is disposed so as to face the upper end surface of the electrode group 5. Yes. The above-described insulating coating applied to the outer periphery of the electrode group 5 extends to the peripheral surface of the positive electrode current collector plate 6. A round hole is formed in the central portion of the positive electrode current collector plate 6, and the positive electrode current collector plate 6 is fixed to the upper end portion of the shaft core 4 at this central portion. The tip of a positive electrode lead piece led out from the positive electrode plate 1 and erected in a substantially vertical direction is welded to the bottom surface of the positive electrode current collector plate 6. Such welding can be performed, for example, by irradiating a laser beam from the upper surface side of the positive electrode current collector plate 6 and welding the bottom surface of the positive electrode current collector plate 6 and the tip of the positive electrode lead piece.

  An assembly member 10 in which a supporter 8 made of an electrically insulating resin and a ring 9 made of an electrically insulating resin are assembled is disposed above the positive electrode current collector plate 6 (see also FIG. 5).

  As shown in FIG. 3, the supporter 8 has a disk-like shape, and a cylindrical portion protruding downward is formed at the center. The outer peripheral surface of the cylindrical portion is fitted and fixed to the upper end portion of the shaft core 4 (see also FIG. 2). A plurality of through-holes 8d formed by being cut out in order to reduce the weight are disposed in the central peripheral portion of the supporter 8. A plurality of arc-shaped grooves 8a are formed on the outer peripheral portion of the through hole 8d so as to form a concentric circle. Eight support portions 8 c protrude from the outer peripheral end surface of the supporter 8. The support portion 8c has a substantially T-shaped or L-shaped cross section. A T-shaped or L-shaped leg portion protrudes from the outer peripheral end surface of the support 8, and the T-shaped or L-shaped arm portion is formed in an arc shape so as to form a concentric circle. The support portion 8 c (arm portion) is in contact with the inner peripheral surface of the battery container 11.

  As shown in FIG. 4, the ring 9 is composed of an annular portion 9 b and a plurality of pins 9 a protruding downward from the annular portion 9 and has an annular shape as a whole. The upper surface 9c of the annular portion 9b is substantially flat (horizontal plane). As shown in FIG. 5, the pin 9 a of the ring 9 is fitted into the groove 8 a of the supporter 8 (fitted and fixed) to constitute the assembly member 10.

  As shown in FIGS. 1 and 2, a disk-shaped battery lid serving as a positive external terminal is disposed above the assembly member 10. The battery lid includes a lid case 16 that functions as a diaphragm in a dish-like shape protruding downward, a lid cap 17, a valve retainer 18 that keeps airtightness, and a cleavage valve 15 that is cleaved by an increase in internal pressure. Are assembled by caulking the periphery of the lid case 16.

  Further, a positive electrode lead 13 formed by superposing a plurality of aluminum ribbons is joined to the upper surface of the positive electrode current collecting plate 6 by laser welding in order to allow large current discharge. The positive electrode lead 13 is also joined to a joining member 23 having a substantially trapezoidal cross section through (through) one of the through holes 8 d of the supporter 8 constituting the assembly member 10. In the manufacturing process, the positive electrode lead 13 is bonded to the positive electrode current collector plate 6 in advance, and after passing through the through hole 8 d, the positive electrode lead 13 is bonded to the bonding member 23. The central portion of the upper surface of the bonding member 23 is bonded to the bottom surface of the lid case 16 with a predetermined strength. For this reason, when the battery internal pressure rises, the lid case 16 is reversed and the joining (electrical connection) between the joining member 23 and the lid case 16 is released. For example, when the battery is abnormal such as overcharge, A structure that prevents thermal runaway of the power generation element is adopted.

  As shown in FIG. 2, the upper surface 9c (of the annular portion 9b) of the ring 9 is in contact with the bottom surface of the battery lid (peripheral portion of the lid case 16) via the spacer member. In this embodiment, since the lid case 16 has a diaphragm function, an example is shown in which the lid case 16 is in contact with the bottom surface of the battery lid via a spacer member. However, as apparent from FIG. You may make it comprise so that the upper surface 9c may contact | abut directly on the bottom face of a battery cover. In other words, the spacer member may be interpreted as a part of the battery lid. In such an aspect, as in the technique of Patent Document 1 described above, the positive electrode lead 13 is directly joined to the bottom of the battery lid.

As shown in FIG. 1, the battery lid is fixed by caulking to the upper part of the battery container 11 via a gasket 19 made of EPDM resin having insulating properties and heat resistance. For this reason, the inside of the lithium ion secondary battery 30 of this embodiment is sealed. Further, a non-aqueous electrolyte (not shown) is injected into the battery container 11. The non-aqueous electrolyte includes, for example, 1 mol / liter of lithium hexafluorophosphate (LiPF ₆ ) as a lithium salt in a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 2: 3. A dissolved one can be used.

  In addition, the lithium ion secondary battery 30 of the present embodiment is a large capacity large battery, and thus operates electrically in response to an increase in battery temperature, as used in a small consumer lithium ion secondary battery. For example, there is no PTC (Positive Temperature Coefficient) element or a current interrupt mechanism that cuts the positive or negative electrical lead as the battery internal pressure increases.

(Effects etc.)
Next, effects and the like of the lithium ion secondary battery 30 of the present embodiment will be described.

  The lithium ion secondary battery 30 of the present embodiment is fixed to the supporter 8 made of an electrically insulating resin and fixed to the upper end portion of the shaft core 4, and fixed to the supporter 8 on the side opposite to the electrode group 5 of the supporter 8. An assembly member 10 assembled with a ring 9 made of an insulating resin is provided, and a support portion 8c of the supporter 8 is in contact with the inner peripheral surface of the battery container 11, and is opposite to the electrode group 5 of the ring 9. The end portion (upper surface 9c) is in contact with the battery lid via the spacer member. According to the lithium ion secondary battery 30, the support portion 8c of the supporter 8 is in contact with the inner peripheral surface of the battery container 11, and the flat surface 9c opposite to the electrode group 5 of the ring 9 is interposed via the battery lid and the spacer member. Therefore, even when vibration or shaking is applied in the vertical and horizontal directions in FIG. 1 when the vehicle is mounted on the vehicle, it is possible to suppress shaking of the electrode group 5 with respect to the battery container 11 and the battery lid. . This is the same when the batteries are juxtaposed (horizontal). Therefore, vibration resistance can be ensured even if the positive electrode current collector plate 6 does not have a large mass and high strength.

  Further, the supporter 8 has a spring function because the support portion 8 c comes into contact with the inner peripheral surface of the battery container 11. With this spring function, even if vibration or shaking acts on the lithium ion secondary battery 30 from the outside, the influence can be suppressed. Furthermore, the assembly member 10 is made of an electrically insulating resin, and the supporter 8 is thinned. For this reason, the weight reduction of the lithium ion secondary battery 30 can be achieved.

  In the present embodiment, the example in which the pin 9a of the ring 9 is fitted into the groove 8a of the supporter 8 to form the assembly member 10 is shown, but the present invention is not limited to this, and for example, shown in FIG. As described above, the member 21 in which the supporter 8 and the ring 9 are integrally formed may be used. By integrating, it is possible to reduce the number of parts and the cost. Further, as shown in FIG. 7, a member 22 in which the supporter 8, the ring 9, and the shaft core 4 are integrated may be used. In such an aspect, it is possible to further reduce the number of parts and the cost.

  Moreover, in this embodiment, although the support part 8c of the supporter 8 showed the example contact | abutted to the internal peripheral surface of the battery container 11, this invention is not restricted to this, A support part is formed in the annular part 9b of the ring 9. The support portion of the ring 9 may be in contact with the inner peripheral surface of the battery container 11.

  Furthermore, although the lithium ion secondary battery for HVE was illustrated in this embodiment, this invention is not limited to this. For example, the present invention can be applied to the PEV battery described in the background section above. In such an embodiment, the assembly member 10 is not only disposed on the positive electrode side as in the present embodiment, but the assembly member is similarly disposed on the negative electrode side, and the current collecting structure on the negative electrode side is also a disc. A negative electrode current collector plate can be used. In this case, if attention is paid to the negative electrode side, it is possible to adopt a structure in which the end of the ring opposite to the electrode group contacts the bottom of the battery container. As a result, a sealed secondary battery having excellent vibration resistance can be obtained without using positive and negative electrodes as a current collecting member having a large mass and high strength.

  Moreover, in this embodiment, although the example which applied the active material mixture to both surfaces of the positive electrode plate 1 and the negative electrode plate 2 was shown, the positive electrode active material mixture coating surface and the negative electrode active material mixture coating surface are In the part which does not oppose, a single-sided application part may exist partially. Furthermore, in the present embodiment, the type and composition of the active material, the blending ratio of the electrode, the type of metal foil, the grade, the thickness, the manufacturing method, etc. are exemplified, but these do not limit the present invention and are generally used. Any of these can be used. Furthermore, the present invention is not limited by the composition and amount of the electrolytic solution exemplified in the embodiment.

  The present invention suppresses the mass of the current collecting member and provides a sealed secondary battery having excellent vibration resistance. Therefore, the present invention contributes to the manufacture and sale of sealed secondary batteries. Have.

It is sectional drawing of the lithium ion secondary battery of embodiment which can apply this invention. It is an expanded sectional view near the battery cover of the lithium ion secondary battery of the embodiment. It is a perspective view of the supporter of the lithium ion secondary battery of an embodiment. It is a perspective view of the ring of the lithium ion secondary battery of embodiment. It is a perspective view of the assembly | attachment member which assembled | attached the supporter and the ring. It is an expanded sectional view near the battery cover of the lithium ion secondary battery of other embodiments to which the present invention is applicable. It is an expanded sectional view near the battery cover of the lithium ion secondary battery of another embodiment to which the present invention is applicable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator 4 Axle core 5 Electrode group 6 Positive electrode current collecting plate (current collecting member)
8 Supporter (disc-shaped member)
8d Through hole 9 Ring (ring-shaped member)
10 Assembly member 11 Battery container 13 Positive electrode lead (a part of current-carrying member)
16 Lid case (part of battery lid)
17 Lid cap (part of battery lid)
23 Joining member (part of current-carrying member)
30 Lithium ion secondary battery

Claims (6)

An electrode group in which a positive electrode plate and a negative electrode plate are wound through a separator around an axis;
A current collecting member disposed opposite to an end face of the electrode group;
An energizing member for connecting the current collecting member to an external terminal;
A disk-shaped member made of an electrically insulating resin fixed to at least one end of the shaft core;
A ring-shaped member made of an electrically insulating resin and fixed to or integrated with the disk-shaped member on the side opposite to the electrode group of the disk-shaped member;
A cylindrical battery container for housing each of the above members;
A battery lid for sealing the battery container;
With
At least a part of the peripheral surface of the disk-shaped member or the ring-shaped member is an inner peripheral surface of the battery container, and the end of the ring-shaped member opposite to the electrode group is the battery lid or the battery container. At least one of the bottom part is in contact,
A convex portion is formed on the lower side of the disk-shaped member, and the convex portion is fitted and fixed to the shaft core,
The disc-shaped member and the ring-shaped member are fitted or formed integrally.
A sealed secondary battery characterized by the above.   The secondary battery according to claim 1, wherein the disk-shaped member, the ring-shaped member, and the shaft core are integrally formed.   At least a part of the peripheral surface of the disk-shaped member or the ring-shaped member is in contact with the inner peripheral surface of the battery container, and the end of the ring-shaped member opposite to the electrode group is the battery. The secondary battery according to claim 1, wherein the secondary battery is in contact with the bottom of the lid directly or via a spacer member.   The disk-shaped member is disposed above the disk-shaped current collecting member, and the current collecting member is fitted and fixed to the shaft core. Next battery.   The secondary battery according to claim 4, wherein a leading end portion of the lead piece led out from the positive electrode plate is joined to a bottom portion of the current collecting member. Wherein the disc-shaped member is formed with a through-hole for lightening, the through conductive member according to claim 4, characterized in that it is electrically connected to the battery lid via the through-hole Secondary battery.

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