JP2009277427A - Secondary battery and secondary battery module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery having a high strength with respect to a load applied from the outside. <P>SOLUTION: The secondary battery 10 is constructed of a wound body 20; a positive electrode current collector 25 which bundles a plurality of current collector leads 21 extended from a positive electrode 14; a negative electrode current collector 42, which bundles a plurality of current collector leads 35 extended from a negative electrode 15; and a battery can 11 to house these wound body 20, the positive electrode current collector 25, and the negative electrode current collector 42. The negative electrode current collector 42 is constructed into a bottomed cylindrical shape made of a bottom part 38 and a skirt part 37 extended from the edge of the bottom part 38; the outer diameter of the bottom part 38 is established shorter by a prescribed length than the inner diameter of the battery can 11; and the top end face 53 of the skirt part 37 is welded to the bottom of the battery can 11. As a result, the top end face 53 can be welded to the bottom 58 and the outer diameter of the skirt part 37 can be made substantially equal to the inside diameter of the battery can 11, thus the joint area is increased to enhance the strength of the secondary battery 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a secondary battery that can be repeatedly used by charging, and a secondary battery module using the secondary battery.

  Secondary batteries are used as a power source for products such as vehicles and mobile phones that require continuous use of electricity.

As a conventional secondary battery, a secondary battery that is electrically connected by welding a negative electrode current collector to the bottom of the battery can is known (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 11-307076 (FIGS. 2 and 4)

Patent document 1 is demonstrated based on the following figure.
FIG. 9 is a diagram for explaining a basic configuration of the conventional technique. In the secondary battery 100, a wound body 103 wound around a winding core 102 and an upper portion of the wound body 103 are disposed in the battery can 101. A positive electrode lead 104 that extends to the positive electrode current collector 106, a positive electrode current collector 106 that bundles the positive electrode lead 104 together with the presser fitting 105, a negative electrode lead 107 that extends from the lower portion of the winding body 103, and a negative electrode lead 107 The negative electrode current collector 109 is accommodated.

  The positive electrode lead 104 is welded to the presser fitting 105 and the positive electrode current collector 106 before being housed in the battery can 101. Similarly, the negative electrode lead 107 is welded to the presser fitting 107 and the negative electrode current collector 109. Next, the negative electrode current collector 109 is welded to the battery can 101. A welding method for welding the negative electrode current collector 109 to the battery can 101 will be described with reference to the next drawing.

  FIG. 10 is a diagram for explaining a conventional method of welding a negative electrode current collector to a battery can. A plurality of protrusions 111, 111 are arranged on the bottom of the negative electrode current collector 109. The protrusions 111 and 111 are brought into contact with the inner surface of the battery can 101, and the welding electrode 112 is inserted from the inside of the winding core 102.

  On the other hand, the welding electrode 113 is brought into contact with the lower surface of the battery can 101. Then, a voltage is applied to the welding electrodes 112 and 113. Then, the protrusion 111 is melted by resistance heat, and the negative electrode current collector 109 is welded to the battery can 101.

  In the secondary battery 100 manufactured as described above, the negative electrode current collector 109 and the battery can 101 can be joined to the winding core 102 through the welding electrode 112. The negative electrode current collector 109 and the battery can 101 can be easily joined, which is beneficial.

  Incidentally, the negative electrode current collector 109 is welded to the vicinity of the center of the battery can 101 by the protrusions 111 and 111. The area of the protrusion 111 is small, and the number of protrusions 111 that can be arranged is limited. That is, the bonding area of the protrusion 111 to the battery can 101 is small.

When such a secondary battery is mounted on a vehicle, the secondary battery receives vibration. Then, tensile stress, compressive stress, or shear stress is generated in the protrusion 11. At this time, since the bonding area at the protrusion 111 is small, the stress increases, and the durability of the secondary battery is adversely affected.
Therefore, it is required to provide a secondary battery with higher strength.

  It is an object of the present invention to provide a secondary battery having high strength against external loads.

The invention according to claim 1 is a winding body in which a positive electrode, a negative electrode, and a separator are integrally wound, a positive electrode current collector that bundles a plurality of current collecting leads extended from the positive electrode, and a negative electrode that extends from the negative electrode. In a secondary battery comprising a negative electrode current collector for bundling a plurality of extended current collector leads, and a battery can for housing these wound body, positive electrode current collector and negative electrode current collector,
The negative electrode current collector is formed in a bottomed cylindrical shape including a bottom surface portion and a skirt portion extending from an edge of the bottom surface portion, and an outer diameter of the bottom surface portion is a predetermined length longer than an inner diameter of the battery can. The tip end surface of the skirt portion is welded to the bottom of the battery can.

  The invention according to claim 2 is characterized in that a plurality of secondary batteries are connected using connection members arranged on the outer peripheral surface of the battery can.

  In the invention which concerns on Claim 1, the front end surface of the skirt part of a negative electrode collector is welded to the bottom of the battery can. The outer diameter of the skirt portion can be increased so as to be approximately equal to the inner diameter of the battery can. As a result, the junction area increases and the strength of the secondary battery can be increased.

  In the invention according to claim 2, a plurality of secondary batteries are connected using a connecting member disposed on the outer peripheral surface of the battery can. That is, the secondary batteries are electrically connected by the connection member at a site close to the weld joint.

  The current flows through the connecting member, the battery can and the negative electrode current collector. By arranging the connecting member in the vicinity of the negative electrode current collector, the current path can be shortened. By shortening the current path, the total amount of internal resistance can be reduced, and energy efficiency can be improved.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a secondary battery according to the present invention. A positive electrode 14, a negative electrode 15, and a separator 16 are integrally wound around a core 12 inside a battery can 11 of the secondary battery 10. A wound body 20 (details will be described later), a current collecting lead 21 extending from the tip of the positive electrode 14 to the upper part of the drawing, a pressing metal 23 disposed on the outer peripheral surface of the tip of the current collecting lead 21, A positive electrode current collector 25 disposed on the inner peripheral surface of the presser fitting 23 and the current collector lead 21 and having a central convex portion 24 fitted to the winding core 12 is welded to the upper surface of the central portion of the positive electrode current collector 25. The positive electrode lead 26 made of aluminum, the lower lid body 28 disposed so that the convex portion 27 is in contact with the central upper surface of the positive electrode lead 26, and the central portion disposed on the upper surface of the lower lid body 28 has a trapezoidal cross section 29. The upper lid body 32 constituted by these, and the upper lid body 32 and the lower lid body 28, an insulator 33 disposed on the outer periphery of the current collector 28, a current collecting lead 35 extending from the tip of the negative electrode 15 to the lower part of the drawing, a pressing metal 36 disposed on the outer peripheral surface of the tip of the current collecting lead 35, The presser fitting 36 and the negative electrode current collector 42 in which the skirt portion 37 is disposed on the inner peripheral surface of the current collecting lead 35 and the concave portion 39 disposed on the bottom surface portion 38 is fitted to the winding core 12 are housed. .
A method for manufacturing such a secondary battery 10 will be described in the following figures.

  FIG. 2 is a diagram for explaining the components of the wound body according to the present invention, and the winding core 12 shown in FIG. 2A can be made of polypropylene, and a welding electrode can be inserted. It has the hollow part 43 formed in the hollow shape.

The positive electrode 14 shown in (b) includes, for example, a positive electrode body 44 made of an aluminum foil having a film thickness of 20 μm, a slurry 45 applied to a part of both surfaces of the positive electrode body 44, and a portion where the slurry 45 is not formed. A plurality of leads 46 formed by punching.
The slurry 45 is formed by dispersing in N-methylpyrrolidone so that the average particle diameter is 6 μm, the nickel-lithium manganate powder is 90% by weight, the acetylene black is 5% by weight, and the vinylidene fluoride resin is 5%. Is done.

  The separator 16 shown in (c) is made of, for example, polypropylene or polyethylene, and has a microporous film.

The negative electrode 15 shown in (d) includes, for example, a negative electrode body 47 made of copper foil having a film thickness of 14 μm, a slurry 48 applied to a part of both surfaces of the negative electrode body 47, and a portion where the slurry 48 is not formed. It comprises a plurality of leads 49 formed by punching.
The slurry 48 is dispersed in N-methylpyrrolidone so that the average particle size is 10 μm, the non-graphitizable carbon powder is 90% by weight, the carbon fiber is 1.5% by weight, and the vinylidene fluoride resin is 8.5%. Formed.

  FIG. 3 is a diagram for explaining a method of manufacturing a wound body according to the present invention. As shown in FIG. 3A, the separator 16, the negative electrode 15, the separator 16, and the positive electrode 14 are stacked in this order from below and wound around one end. A wick 12 is placed. When the positive electrode 14, the negative electrode 15, and the separator 16 are wound around the winding core 12, as illustrated in FIG. 5B, the wound body 20 in which the positive electrode 14, the negative electrode 15, and the separator 16 are integrally wound. Is manufactured.

  FIG. 4 is an enlarged view of a portion 4 in FIG. 1, and the plurality of current collecting leads 21 are welded while being sandwiched between the positive electrode current collector 25 and the holding metal fitting 23. The current collector lead 21, the positive electrode current collector 25, and the presser fitting 23 are electrically connected.

This welding can be performed before storing in a battery can (battery can 11 in FIG. 1). Since it can be performed before storing the battery can, welding work can be easily performed.
As a welding method, ultrasonic welding, laser welding, or the like can be used. That is, the welding method is not limited as long as the current collecting lead 21, the positive electrode current collector 25, and the presser fitting 23 can be electrically connected.

  FIG. 5 is an enlarged view of 5 parts in FIG. 1, and the plurality of current collecting leads 35 are welded while being sandwiched between the skirt portion 37 and the holding metal fitting 36 of the negative electrode current collector 42. The current collecting lead 35, the skirt portion 37, and the presser fitting 36 are electrically connected.

  The tip of the skirt portion 37 is formed in a trapezoidal cross section, and the tip surface 53 is welded to the inside of the battery can 11 (details will be described later). The negative electrode current collector 42 is electrically connected to the battery can 11 through a nugget 54 generated by welding.

  The outer diameter of the bottom surface portion 38 is smaller than the inner diameter of the battery can 11 by the thickness of the presser fitting 36 and the thickness of the current collecting lead 35. If the current collector lead 35 is welded to the skirt portion 37 without using the presser fitting 36, the outer diameter of the bottom surface portion can be brought closest to the inner diameter of the battery can 11.

  The current collector lead 35, the skirt portion 37, and the presser fitting 36 can be welded before being stored in the battery can (battery can 11 in FIG. 1). Since it can be performed before storing the battery can, welding work can be easily performed.

  As a welding method, ultrasonic welding, laser welding, or the like can be used. That is, the welding method is not limited as long as the current collecting lead 35, the skirt portion 37, and the presser fitting 36 can be electrically connected.

FIG. 6 is an explanatory diagram when the negative electrode current collector according to the present invention is welded to the inside of the battery can, and the negative electrode current collector 42 is welded to the battery can 11 by projection welding.
That is, one welding electrode 56 is lowered through the hollow portion 43 of the winding core 12 to a position where the welding electrode 56 contacts the concave portion 39 of the negative electrode current collector 42. The other welding electrode 57 is disposed below the front end surface 53 from the bottom 58 of the battery can 11. At this time, the battery can 11 is supported using the support rod 59.

Next, a voltage is applied. The negative electrode current collector 42 can be welded to the battery can 11 by the resistance heat at this time.
Weld several places in the same way. Alternatively, welding is performed linearly along the tip surface 53.

When the negative electrode current collector 42 is welded to the battery can 11, the electrolyte is injected and the lid bodies (the upper lid body 32 and the lower lid body 28 in FIG. 1) are arranged.
As the electrolytic solution, for example, a solution obtained by dissolving 1 mol / L LiPF ₆ (lithium salt) in a mixed solvent of ethylene carbonate and ethyl methyl carbonate can be used.

  The front end surface 53 of the skirt portion 37 of the negative electrode current collector 42 is welded to the bottom 58 of the battery can 11. The outer diameter of the skirt portion 37 can be increased so as to be substantially equal to the inner diameter of the battery can 11. As a result, the junction area increases and the strength of the secondary battery 10 can be increased.

  FIG. 7 is an explanatory diagram of a secondary battery module according to the present invention. The secondary battery module 60 includes a secondary battery 10a in which a negative electrode terminal 62 is disposed at one end and an insulating ring 63 is disposed at the other end. The secondary battery 10b is connected to the secondary battery 10a, welded to the first connection member 64 at one end, and disposed at the other end with the insulating ring 63, and electrically connected to the secondary battery 10b via the second connection member 65. A secondary battery 10c in which insulating rings 63 and 63 are disposed at both ends, a secondary battery 10d connected to the secondary battery 10c and having one end connected to the other end of the first connection member 64 and a positive electrode terminal 66 welded thereto. Consists of

  The secondary batteries 10a, 10b, 10c and 10d are electrically connected via connection members 64 and 65.

  FIG. 8 is an enlarged view of 8 parts in FIG. 7, and the current passing through the first connection member 64 as indicated by the arrow (1) is transferred from the first connection member 64 to the battery can 11 as indicated by the arrow (2). It passes through a nugget 67 that is formed when welding.

  The current passing through the nugget 67 travels through the battery can 11 and reaches the skirt portion 37 as indicated by the arrow (3), and is transmitted to the current collecting lead 21 as indicated by the arrow (4).

  A plurality of secondary batteries 10b were connected using a connection member 64 disposed on the outer peripheral surface of the battery can 11. The connection member 64 is disposed on the outer peripheral surface of the battery can. On the other hand, the negative electrode current collector 42 of the secondary battery 10 is welded along the inner peripheral surface of the battery can 11. That is, the length L from the negative electrode current collector 42 to the connection members 64 and 65 is short.

  The current flows through the connection member 64, the battery can 11, and the negative electrode current collector 42. By arranging the connection member 64 in the vicinity of the negative electrode current collector 42, the current path can be shortened. By shortening the current path, the total amount of internal resistance can be reduced, and energy efficiency can be improved.

  The secondary battery of the present invention is suitable for a vehicle-mounted secondary battery.

It is sectional drawing of the secondary battery which concerns on this invention. It is a figure explaining the component of the winding body which concerns on this invention. It is a figure explaining the manufacturing method of the winding body concerning the present invention. FIG. 4 is an enlarged view of part 4 of FIG. 1. FIG. 5 is an enlarged view of part 5 of FIG. 1. It is explanatory drawing at the time of welding the negative electrode collector which concerns on this invention inside a battery can. It is explanatory drawing of the secondary battery module which concerns on this invention. FIG. 8 is an enlarged view of 8 parts in FIG. 7. It is a figure explaining the basic composition of the conventional technology. It is a figure explaining the welding method to the battery can of the conventional negative electrode collector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 11 ... Battery can, 14 ... Positive electrode, 15 ... Negative electrode, 16 ... Separator, 20 ... Winding body, 21, 35 ... Current collector lead, 25 ... Positive electrode current collector, 37 ... Skirt part, 38 ... bottom surface part, 42 ... negative electrode current collector, 53 ... tip surface, 58 ... bottom, 60 ... secondary battery module, 64, 65 ... connection member.

Claims (2)

A winding body in which a positive electrode, a negative electrode, and a separator are integrally wound, a positive electrode current collector that bundles a plurality of current collecting leads extended from the positive electrode, and a plurality of current collecting leads extended from the negative electrode In a secondary battery comprising a negative electrode current collector that bundles and a battery can for housing these wound body, positive electrode current collector and negative electrode current collector,
The negative electrode current collector is formed in a bottomed cylindrical shape including a bottom surface portion and a skirt portion extending from an edge of the bottom surface portion, and an outer diameter of the bottom surface portion is a predetermined length longer than an inner diameter of the battery can. The secondary battery is characterized in that it is set to be short and the front end surface of the skirt is welded to the bottom of the battery can.   A secondary battery module, wherein a plurality of the secondary batteries according to claim 1 are connected using a connection member disposed on an outer peripheral surface of the battery can.

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