JP4401203B2 - Square battery - Google Patents

Description

  The present invention relates to a prismatic battery configured by accommodating a wound electrode body serving as a battery element inside a rectangular parallelepiped.

  In recent years, lithium ion secondary batteries with high energy density (Wh / Kg) have been developed as power sources for portable electronic devices, electric vehicles, etc. Among them, rectangular secondary batteries with high volume energy density (Wh / l) have been developed. Batteries are attracting attention (see Patent Documents 1 and 2).

7 and 9 show the configuration of the prismatic secondary battery according to the applicant's proposal . As shown in FIG. 7 , a rectangular parallelepiped can body (11) and a seal covering the opening of the can body (11). A winding electrode body (2) serving as a power generation element is accommodated in a battery can (1) formed by the body (12). The sealing body (12) is provided with a pair of positive and negative electrode terminal mechanisms (4) and (40), and when the internal pressure exceeds a predetermined value between the electrode terminal mechanisms (4) and (40). A gas discharge valve (13) to be opened and an injection plug (14) for closing the through hole for injecting the electrolyte are provided. The winding electrode body (2) is accommodated horizontally in the can body (1) and has a flat shape in a direction perpendicular to the winding axis.

As shown in FIG. 9 , strip-shaped current collector plates (3) and (30) are joined to both electrode edges (28) and (29) of the take-up electrode body (2), and the current collector plates (3) ( 30) is connected to a pair of positive and negative electrode terminal mechanisms (4) and (40) via lead members (5) and (50) formed by plastic processing of a metal plate. As a result, the electric power generated by the take-up electrode body (2) can be taken out from the pair of electrode terminal mechanisms (4) and (40).

Each of the current collector plates (3) and (30) has a strip-shaped flat plate portion (31), and protrudes toward both ends of the flat plate portion (31) toward the electrode edges (28) and (29). A pair of ribs (32) and (32) are formed along the both end portions. The flat plate portion (31) is provided with a plurality of protruding strip portions (33) extending in a direction intersecting with the pair of ribs (32) and (32) and projecting toward the electrode end edges (28) and (29). A plurality of through-holes (34) are opened between the adjacent ridges (33).
JP 2002-93402 A JP-A-7-296790

However, in the above-described prismatic secondary battery, the winding electrode body (2) expands in the radial direction around the winding axis by absorbing the electrolyte, and as shown in FIG. The outer peripheral surface of 2) sometimes adhered to the gas discharge valve (13) attached to the sealing plate (12) of the battery can (1). As a result, the gas flow path of the gas discharge valve (13) is blocked, and there is a problem that the gas discharge function of the gas discharge valve (13) is hindered when the internal pressure of the battery rises and exceeds a predetermined value. It was.

To solve this problem, a configuration in which a gas discharge valve (13) is provided on the side surface of the can body (11) of the battery can (1) can be considered (refer to Patent Document 2), but gas can be discharged to the can body (11). It is difficult to manufacture the valve (13), and there is a problem that leads to an increase in cost.
Accordingly, an object of the present invention is to provide a prismatic battery that does not interfere with the gas discharge function of the gas discharge valve without changing the configuration of disposing the gas discharge valve on the sealing plate of the battery can.

In the rectangular battery according to the present invention, a winding electrode body (battery element) is formed inside a battery can (1) in which a sealing plate (12) is fixed to an opening of a can body (11) having a rectangular parallelepiped shape. 2), a pair of positive and negative electrode edges (28) which are accommodated along the outer peripheral surface of the can body (11) and project at both ends in the winding axis direction of the wound electrode body (2). 29) are joined to current collector plates (3) and (30), respectively, and both current collector plates (3) and (30) are respectively connected via lead members (5) and (50) formed by plastic processing of metal plates. The positive and negative electrode terminal mechanisms (4) and (40) attached to the sealing plate (12) are connected to each other.
The sealing plate (12) of the battery can (1) is positioned at a position facing the surface of the lead member (5) extending from one of the current collector plates (3) to the corresponding electrode terminal mechanism (4). A gas discharge valve (13) to be opened when the internal pressure exceeds a predetermined value is attached.

  In a specific configuration, the pair of electrode terminal mechanisms (4) and (40) are arranged on the sealing plate (12) of the battery can (1) along the winding axis direction of the winding electrode body (2). In addition, the gas discharge valve (13) is disposed outside the both electrode terminal mechanisms (4) and (40).

  In the prismatic battery of the present invention, the winding electrode body (2) expands in the radial direction due to absorption of the electrolytic solution, and the outer peripheral surface of the winding electrode body (2) approaches the gas discharge valve (13). However, since the lead member (5) extends at a position facing the gas discharge valve (13), the outer peripheral surface of the winding electrode body (2) is received by the lead member (5). As a result, a space between the gas discharge valve (13) and the lead member (5) is maintained, thereby ensuring the gas discharge function of the gas discharge valve (13).

  According to the prismatic battery according to the present invention, the gas discharge function of the gas discharge valve when the battery internal pressure rises can be satisfactorily maintained without changing the configuration of disposing the gas discharge valve on the sealing plate of the battery can.

  Hereinafter, the embodiment in which the present invention is applied to a prismatic lithium ion secondary battery will be specifically described with reference to the drawings.

First Embodiment As shown in FIG. 1, a prismatic lithium ion secondary battery according to the present invention has a battery can (1) in which a sealing body (12) is welded and fixed to an opening of a rectangular parallelepiped can body (11). A winding electrode body (2) serving as a power generation element is accommodated in the battery can (1). The take-up electrode body (2) has a flat shape in a direction perpendicular to the winding axis, and is accommodated sideways in the can body (1). The battery can (1) has an outer shape of, for example, 17 mm × 50 mm × 90 mm.

  The sealing body (12) of the battery can (1) is provided with a pair of positive and negative electrode terminal mechanisms (4) and (40), and between the electrode terminal mechanisms (4) and (40), for electrolyte injection. A liquid injection plug (14) that closes the through hole of the gas is provided, and a gas discharge valve (13) that should be opened when the internal pressure exceeds a predetermined value is provided outside the electrode terminal mechanisms (4) and (40). Has been.

  As shown in FIG. 6, the take-up electrode body (2) is formed by interposing a strip-shaped separator (22) between the strip-shaped positive electrode (21) and the negative electrode (23) and winding them in a spiral shape. Has been. The positive electrode (21) is configured by applying a positive electrode active material (24) made of lithium cobaltate on both sides of a strip-like core (25) made of an aluminum foil having a thickness of 15 μm, and the negative electrode (23) is made to have a thickness of 10 μm. The negative electrode active material (26) made of graphite is applied to both surfaces of a strip-like core (27) made of copper foil. The separator (22) is an ion-permeable polypropylene microporous membrane, and the separator (22) is impregnated with a non-aqueous electrolyte.

The positive electrode (21) is formed with a coated portion where the positive electrode active material (24) is applied and an uncoated portion where the positive electrode active material (24) is not applied. The negative electrode (23) is also formed with a coated portion where the negative electrode active material (26) is applied and a non-coated portion where the negative electrode active material is not applied.
The positive electrode (21) and the negative electrode (23) are respectively shifted and overlapped on the separator (22) in the width direction, and the non-coated portions of the positive electrode (21) and the negative electrode (23) are separated from both end edges of the separator (22). Each protrudes outward. And after winding these up in a spiral shape, the winding electrode body (2) which has a flat shape in the direction perpendicular | vertical to a winding axis | shaft is formed by compressing the outer peripheral surface of an electrode body from both sides. A central hole (210) penetrating both ends is formed in the central portion of the winding electrode body (2).

  At one end of the wound electrode body (2), the edge of the core body (25) of the plurality of positive electrodes (21) protrudes to form the electrode edge (28) on the positive electrode side, and the other The edge of the core body (27) of the plurality of negative electrodes (23) protrudes from the end of the negative electrode (29) to form an electrode edge (29) on the negative electrode side. As shown in FIG. 3, a pair of positive and negative belt-shaped current collector plates (3) and (30) are joined to each other.

Both current collector plates (3) and (30) each have a strip-shaped flat plate portion (31), and project at both ends in the width direction of the flat plate portion (31) toward the electrode edges (28) and (29). A pair of ribs (32) and (32) are formed along the both end portions. The flat plate portion (31) is provided with a plurality of protruding strip portions (33) extending in a direction intersecting with the pair of ribs (32) and (32) and projecting toward the electrode end edges (28) and (29). A plurality of through-holes (34) are opened between the adjacent ridges (33).
The current collecting plates (3) and (30) have a thickness of 0.5 mm, the flat plate portion (31) has an outer shape of 14 mm × 50 mm, and the rib (32) has an outer shape of 20 mm × 50 mm.

  FIG. 5 shows the structure of another current collector plate (3) (30). In the current collector plates (3) and (30), they protrude toward the electrode edges (28) and (29) of the winding electrode body (2) between the adjacent protrusions (33) and (33), respectively. A pair of cut and raised pieces (35) and (35) are formed. Both the cut and raised pieces (35) and (35) extend in the longitudinal direction of the flat plate portion (31) and are about 120 degrees with respect to the surface facing the electrode edges (28) and (29) of the flat plate portion (31). Has an opening angle. The opening (36) formed in the flat plate portion (31) as the cut and raised pieces (35) and (35) are cut and raised impregnates the winding electrode body (2) with the electrolytic solution in the assembly process described later. It becomes a passage when letting go.

As shown in FIG. 3, each of the pair of current collector plates (3) and (30) is a lead member (5) (50) formed by plastic working a metal plate having a thickness of 0.5 mm to 1.5 mm into an L shape. And is connected to the base end of the pair of positive and negative electrode terminal mechanisms (4), (40). The lead member (5) on the positive electrode side is made of aluminum, and the lead member (50) on the negative electrode side is made of nickel.
The proximal ends of the lead members (5) and (50) are welded to the current collector plates (3) and (30), and the distal ends are caulked and fixed to the proximal ends of the electrode terminal mechanisms (4) and (40).
Here, as shown in FIG. 4, one lead member (5) extends between the outer peripheral surface of the wound electrode body (2) and the sealing plate (12), and the tip thereof is the electrode terminal mechanism (4). The gas discharge valve (13) faces the surface of the lead member (5).

  In the above-described prismatic lithium ion secondary battery of the present invention, as shown in FIG. 2, the winding electrode body (2) expands in the radial direction due to absorption of the electrolytic solution, and the outer circumferential surface of the winding electrode body (2) Even when approaching the gas discharge valve (13), the lead member (5) extends at a position facing the gas discharge valve (13). The outer peripheral surface of 2) is received. As a result, a space (gas flow path) between the gas discharge valve (13) and the lead member (5) is maintained, thereby ensuring the gas discharge function of the gas discharge valve (13).

In the assembly of the prismatic secondary battery of the first embodiment, first, the can body (11), the sealing plate (12), and the winding electrode body (2) shown in FIG. Current collector plates (3) and (30) and lead members (5) and (50) are prepared.
Next, the current collector plates (3) and (30) are pressed against the electrode edges (28) and (29) protruding from both ends of the wound electrode body (2). Here, the rigidity of the current collector plates (3) and (30) is large due to the pair of ribs (32) and (32) and the ridges (33) formed by pressing. (3) There is no possibility that the flat plate portion (31) of the current collector plates (3) and (30) is deformed by the pressing force pressing the electrode edges (28) and (29).
By pressing the current collector plates (3) and (30) against the electrode edges (28) and (29), respectively, the ridges (33) of the current collector plates (3) and (30) become the electrode edges (28). (29) is uniformly bitten, and a joint portion formed of a cylindrical surface is formed between each protrusion (33) and the electrode edge (28) (29).

  Further, the end portions of the plurality of cores of the winding electrode body (2) are directed toward the center of the flat plate portion (31) of the current collecting plates (3) and (30) by the pair of ribs (32) and (32). They are gathered and bundled. Accordingly, the current collector plates (3) and (30) are positioned with respect to the electrode edges (28) and (29), respectively, and the positions of the current collector plates (3) and (30) are wound up. There is no deviation in the thickness direction of the electrode body (2).

  In this way, the current collector plates (3) and (30) are pressed against the electrode edges (28) and (29) of the winding electrode body (2), and are directed toward the inner peripheral surface of each protrusion (33). The laser beam is irradiated and laser welding is performed. At this time, the electrode edges (28) and (29) are in contact with the current collector plates (3) and (30) in a state in which the end portions of the plurality of core bodies are more tightly bundled than in the prior art. Even when welding is performed with a large output and a large welding heat is generated in the welded joint, the welded joint does not melt, and both current collector plates (3) and (30) have their respective electrode edges. (28) It is securely joined to (29).

  Then, the pair of positive and negative electrode terminal mechanisms (4), (40) are assembled to the sealing plate (12), and the tip ends of the pair of lead members (5), (50) are attached to the electrode terminal mechanisms (4), (40). Secure by caulking. Thereafter, the base ends of the lead members (5) and (50) are laser-welded to the back surfaces of the flat plate portions (31) of the current collector plates (3) and (30), respectively.

Next, the take-up electrode body (2) is accommodated inside the can body (11), and the sealing plate (12) is placed over the opening of the can body (11), and the sealing plate (12) is placed on the can body (11 ).
Thereafter, an electrolytic solution is injected from the injection hole of the sealing plate (12) in the dry box. At this time, since the electrolytic solution is supplied into the winding electrode body (2) from the through holes (34) of the current collector plates (3) and (30), the winding electrode body (2) is impregnated with the electrolytic solution. Therefore, the time for injecting the electrolyte into the battery can (1) is greatly reduced. Finally, the liquid injection hole is sealed with a liquid injection stopper (14), and the assembly of the battery is completed.

  As described above, according to the prismatic lithium ion secondary battery according to the present invention, without changing the configuration of disposing the gas discharge valve (13) on the sealing plate (12) of the battery can (1), the battery internal pressure can be increased. The gas discharge function of the gas discharge valve (13) can be kept good.

1 is a perspective view showing an appearance of a prismatic lithium ion secondary battery that is a first embodiment of the present invention. FIG. It is a figure explaining the effect of this square lithium ion secondary battery. It is a disassembled perspective view of this square lithium ion secondary battery. It is a perspective view which shows the positional relationship of the lead member and gas exhaust valve in this square lithium ion secondary battery. It is a perspective view which shows the other structure of a current collection board. It is a partial expansion perspective view of a winding electrode body. It is a perspective view which shows the external appearance of the square lithium ion secondary battery based on an applicant's proposal. . It is a figure explaining the malfunction in this square lithium ion secondary battery. It is a disassembled perspective view of this square lithium ion secondary battery.

Explanation of symbols

(1) Battery can
(11) Can body
(12) Sealing plate
(13) Gas discharge valve
(14) Injection stopper
(2) Winding electrode body
(3) Current collector
(30) Current collector
(4) Electrode terminal mechanism
(40) Electrode terminal mechanism
(5) Lead material
(50) Lead material

Claims (2)

  A winding electrode body (2) serving as a battery element is disposed inside the battery can (1) in which the sealing plate (12) is fixed to the opening of the can body (11) having a rectangular parallelepiped shape. A pair of positive and negative electrode edges (28), (29), which are accommodated along the bottom surface of the main body (11) and project from both ends in the winding axis direction of the winding electrode body (2), ) (30) are joined to each other, and both current collector plates (3) and (30) are respectively attached to the sealing plate (12) via lead members (5) and (50) formed by plastic processing of metal plates. In the rectangular battery connected to the pair of positive and negative electrode terminal mechanisms (4), (40), the sealing plate (12) of the battery can (1) has a corresponding electrode from one of the current collector plates (3). A square battery characterized in that a gas discharge valve (13) to be opened when the internal pressure exceeds a predetermined value is attached at a position facing the surface of the lead member (5) extending to the terminal mechanism (4). . The sealing plate (12) of the battery can (1) is provided with the pair of electrode terminal mechanisms (4) and (40) along the winding axis direction of the winding electrode body (2), and both electrode terminals. The prismatic battery according to claim 1, wherein the gas discharge valve (13) is arranged outside the mechanism (4) (40).