JP4159299B2 - Secondary battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a secondary battery in which a wound electrode body serving as a secondary battery element is accommodated in a battery can and power generated by the wound electrode body can be taken out from a pair of electrode terminal portions provided in the battery can. Is.
[0002]
[Prior art]
In recent years, lithium ion secondary batteries with high energy density have attracted attention as power sources for portable electronic devices and electric vehicles. For example, in a relatively large capacity cylindrical lithium ion secondary battery used for an electric vehicle, as shown in FIGS. 9 and 10, lids (12) and (12) are fixed to both ends of a cylindrical body (11) by welding. A winding electrode body (4) is housed in a cylindrical battery can (1). A pair of positive and negative electrode terminal mechanisms (9), (9) is attached to both the lids (12), (12), and both poles of the winding electrode body (4) and both electrode terminal mechanisms (9), (9) Are connected to each other, and the electric power generated by the winding electrode body (4) can be taken out from the pair of electrode terminal mechanisms (9) and (9). Each lid (12) is provided with a pressure open / close gas discharge valve (13).
[0003]
As shown in FIG. 11, the wound electrode body (4) is formed by interposing a strip-shaped separator (42) between a strip-shaped positive electrode (41) and a negative electrode (43), and winding them in a spiral shape. It is configured. The positive electrode (41) is configured by applying a positive electrode active material (44) made of a lithium composite oxide on both surfaces of a belt-like core (45) made of an aluminum foil, and the negative electrode (43) is made of a belt-like core made of a copper foil. The negative electrode active material (46) containing a carbon material is applied to both surfaces of the body (47). The separator (42) is impregnated with a non-aqueous electrolyte.
[0004]
Here, the positive electrode (41) and the negative electrode (43) are superimposed on the separator (42) while being shifted in the width direction, and wound in a spiral shape. As a result, the end of the core body (45) of the positive electrode (41) is more outward than the edge of the separator (42) at one end of both ends in the winding axis direction of the winding electrode body (4). The edge (48) protrudes, and at the other end, the end edge (48) of the core (47) of the negative electrode (43) protrudes outward from the end edge of the separator (42).
Disc-shaped current collector plates (5) are welded to both ends of the winding electrode body (4), and strip-shaped lead portions (55) projecting from the current collector plate (5) are shown in FIG. 10 is connected to the proximal end portion of the electrode terminal mechanism (9) shown in FIG.
[0005]
The electrode terminal mechanism (9) includes an electrode terminal (91) attached through the lid (12) of the battery can (1). A flange (92) is provided at the base end of the electrode terminal (91). Is formed. An insulating packing (93) is attached to the through hole of the lid (12), and electrical insulation and sealing between the lid (12) and the fastening member (91) are maintained. A washer (94) is fitted to the electrode terminal (91) from the outside of the lid (12), and a first nut (95) and a second nut (96) are screwed together. The first nut (95) is tightened and the insulating packing (93) is clamped by the flange (92) and the washer (94) of the electrode terminal (91), thereby improving the sealing performance.
The tip of the lead part (55) of the current collector plate (5) is fixed to the flange (92) of the electrode terminal (91) by spot welding or ultrasonic welding.
[0006]
By the way, in particular, in a lithium ion secondary battery used as a power source for an electric vehicle, it is necessary to reduce the internal resistance as much as possible in order to obtain a high capacity and a high output.
Therefore, in order to reduce the internal resistance of the secondary battery, in the current collecting structure shown in FIG. 11, the flat plate body (51) of the current collecting plate (5) extends radially around the central hole (54). A plurality of arc-shaped convex portions (52) are integrally formed and protrude toward the winding electrode body (4). The flat plate body (51) is formed with a plurality of cut and raised pieces (53) between the adjacent arc-shaped convex portions (52) and (52), and the winding electrode body (4) side is formed. Protruding.
[0007]
In the manufacturing process of the secondary battery having the current collecting structure, the current collecting plate (5) is pressed against the core body edge (48) formed at the end of the winding electrode body (4). Thereby, the arc-shaped convex part (52) of the current collector plate (5) bites into the core body edge (48) of the winding electrode body (4), and the arc-shaped convex part (52) and the core body edge ( Between 48), a joining surface comprising a cylindrical surface is formed. Further, the cut-and-raised piece (53) of the current collector plate (5) bites deeply into the core body edge (48) of the winding electrode body (4) and is crimped to the core body edge (48). .
[0008]
In this state, a laser beam is irradiated toward the inner peripheral surface of the arc-shaped convex portion (52) of the current collector plate (5) to perform laser welding. As a result, the arc-shaped convex part (52) of the current collector plate (5) and the core body edge (48) of the winding electrode body (4) are joined to each other with a large contact area, and the cut and raised pieces The pressure-bonded state between (53) and the core body edge (48) is maintained.
[0009]
Therefore, the current collector plate (5) is joined to the core end edge (48) with a large contact area at each arc-shaped convex portion (52) and the welded portion of the core end edge (48). In a region other than the portion, each cut-and-raised piece (53) bites into the core edge (48) and a good contact state is obtained, so that the current collector plate (5) and the winding electrode body (4) The contact resistance between them becomes small. However, since current is collected from the entire area of the core end edge (48) by the plurality of cut and raised pieces (53) formed on the current collecting plate (5), high current collecting performance is obtained.
[0010]
[Problems to be solved by the invention]
However, in the current collecting structure in which the lead portion (55) protruding from the current collecting plate (5) is connected to the electrode terminal mechanism (9) as shown in FIG. 10, the winding plate (4) to the current collecting plate (5 ) Lead portion (55) extending from the end of the flat plate body (51) of the current collector plate (5) to the electrode terminal (91) in the current path from the lead portion (55) to the electrode terminal mechanism (9). However, since the cross-sectional area is small, the electric resistance of the current path formed by the lead portion (55) is large, and the internal resistance cannot be sufficiently reduced.
[0011]
Further, since it is necessary to provide a space in which the lead portion (55) extends between the current collector plate (5) in the battery can (1) and the electrode terminal (91) of the electrode terminal mechanism (9), the battery can There has been a problem that the output per unit volume of the secondary battery is small because the volume of (1) is large.
[0012]
Therefore, an object of the present invention is to further reduce the internal resistance and increase the output per unit volume in a secondary battery having a current collecting structure using a current collecting plate.
[0013]
[Means for solving the problems]
In the secondary battery according to the present invention, the battery can (1) is wound in a spiral shape with a separator (42) interposed between the strip-shaped positive electrode (41) and the negative electrode (43), respectively. The electrode body (4) is accommodated, and the positive electrode (41) and the negative electrode (43) are each formed by applying an active material to the surface of the belt-like core body, and the electric power generated by the winding electrode body (4) is supplied to a pair. It can be taken out from the electrode terminal.
The edge (48) of the strip-shaped core constituting the positive electrode (41) or the negative electrode (43) protrudes at the end of at least one of the winding electrode body (4) and covers the edge (48). The current collector plate (50) is installed, and the current collector plate (50) is connected to one of the electrode terminal portions.
Further, the current collector plate (50) is provided with a boss (56) that closely fits into the central hole (40) of the winding electrode body (4), and the one of the bosses (56) is inserted into the boss (56). The end of the electrode terminal protrudes and is fixed to the boss (56), and the end of the electrode terminal is pressed against the surface of the current collector plate (50) in the vicinity of the fixed position.
[0014]
In the secondary battery of the present invention, the end portion of the electrode terminal portion is directly pressed against the surface of the current collector plate (50) to form a current path from the winding electrode body (4) to the electrode terminal. In addition, since the conventional lead portion is not interposed, the electric resistance of the current path is small.
Further, in order to fix the end portion of the electrode terminal portion to the surface of the current collector plate (50) in a pressure contact state, inside the boss (56) fitted into the central hole (40) of the winding electrode body (4), Since the structure of fixing the end portion of the electrode terminal portion to the current collector plate (50) is adopted, the fixing structure is accommodated in the central hole (40) of the winding electrode body (4). No extra space is required to place the fixed structure.
[0015]
In a specific configuration, the one electrode terminal portion includes an electrode terminal (91) penetrating the battery can (1), and the electrode terminal (91) is in pressure contact with the surface of the current collector plate (50). A power flange (92) and a screw shaft piece (97) projecting from the flange (92) to the winding electrode body (4) side are formed, and the inner periphery of the boss (56) of the current collector plate (50) A screw shaft piece (97) of the electrode terminal (91) is screwed into an inner screw (57) formed on the surface.
[0016]
In the assembly process of the secondary battery having the specific configuration, the winding electrode body (4) is wound in a state where the boss (56) of the current collector plate (50) is fitted into the central hole (40) of the winding electrode body (4). After the current collector plate (50) is welded to the core body edge (48) of the electrode body (4), the electrode terminal (91) is connected to the internal thread (57) of the boss (56) of the current collector plate (50). ) And screw the flange (92) against the surface of the current collector plate (50).
As a result, the flange (92) of the electrode terminal (91) is directly pressed against the surface of the current collector plate (50) in a wide area, and the electrode is passed from the winding electrode body (4) through the current collector plate (50). A current path with the shortest distance to the terminal (91) is formed. As a result, the electric resistance of the current path becomes smaller than in the conventional case.
[0017]
【The invention's effect】
According to the secondary battery according to the present invention, the internal resistance can be further reduced and the output per unit volume can be increased as compared with the conventional battery.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the embodiment in which the present invention is applied to a lithium ion secondary battery will be specifically described with reference to the drawings.
Lithium ion secondary battery according to the overall configuration <br/> present invention, as shown in FIG. 1, the tubular body (11) at both ends in the lid (12) a cylindrical battery (12) formed by welding fixation The take-up electrode body (4) is accommodated inside the can (1). A pair of positive and negative electrode terminal mechanisms (90), (90) is attached to the lids (12), (12). Each lid (12) is provided with a pressure open / close type gas discharge valve (13).
Current collector plates (50) are respectively installed at both ends of the winding electrode body (4), and are laser welded to the core body edge (48). The surface of the current collector plate (50) is in pressure contact with the flange (92) of the electrode terminal (91) constituting the electrode terminal mechanism (90).
[0019]
Winding electrode body ( 4 )
As shown in FIG. 11, the wound electrode body (4) is formed by interposing a strip-shaped separator (42) between a strip-shaped positive electrode (41) and a negative electrode (43), and winding them in a spiral shape. It is configured. The positive electrode (41) is configured by applying a positive electrode active material (44) made of a lithium composite oxide on both surfaces of a belt-like core (45) made of an aluminum foil, and the negative electrode (43) is made of a belt-like core made of a copper foil. The negative electrode active material (46) containing a carbon material is applied to both surfaces of the body (47). The separator (42) is impregnated with a non-aqueous electrolyte.
[0020]
The positive electrode (41) is formed with a coated portion where the positive electrode active material (44) is applied and a non-coated portion where the positive electrode active material is not applied. The negative electrode (43) is also formed with a coated portion where the negative electrode active material (46) is applied and a non-coated portion where the negative electrode active material is not applied.
The positive electrode (41) and the negative electrode (43) are respectively superimposed on the separator (42) while being shifted in the width direction, and the uncoated portions of the positive electrode (41) and the negative electrode (43) are separated from both end edges of the separator (42). Each protrudes outward. And a winding electrode body (4) is comprised by winding up these in the shape of a spiral. In the wound electrode body (4), the core body edge (48) of the non-coated portion of the positive electrode (41) is at one end of the both ends in the winding axis direction of the separator (42). Projects outward from one edge, and at the other end, the core body edge (48) of the non-coated part of the negative electrode (43) is outward from the other edge of the separator (42). It protrudes.
[0021]
Electrode terminal mechanism (90)
As shown in FIG. 1, the electrode terminal mechanism (90) includes an electrode terminal (91) made of a bolt member attached through the lid (12) of the battery can (1). A disk-shaped flange (92) is formed at the base end of the electrode terminal (91), and a screw shaft piece is formed on the back surface of the flange (92) toward the winding electrode body (4). (97) is projected.
An insulating packing (93) is attached to the through hole of the lid (12), and electrical insulation and sealing between the lid (12) and the fastening member (91) are maintained. A washer (94) is fitted to the electrode terminal (91) from the outside of the lid (12), and a first nut (95) and a second nut (96) are screwed together. The first nut (95) is tightened and the insulating packing (93) is clamped by the flange (92) and the washer (94) of the electrode terminal (91), thereby improving the sealing performance.
[0022]
Current collecting structure The current collecting plate (50) includes a disc-shaped main body (51) as shown in FIGS. 2 to 4, and the disc-shaped main body (51) includes a plurality of radially extending strips ( In the embodiment, four (4) arc-shaped convex portions (52) are integrally formed and project to the winding electrode body (4) side. Further, the disc-shaped main body (51) is formed with a plurality of (two in the embodiment) cut and raised pieces (53) between the adjacent arc-shaped convex portions (52) and (52), It protrudes to the winding electrode body (4) side. Here, the through-hole opened with the formation of the cut-and-raised piece (53) functions as an electrolyte solution passage.
Furthermore, a cylindrical boss (56) that can be fitted into the central hole (40) of the winding electrode body (4) is projected on the surface of the flat plate body (51) facing the winding electrode body (4). On the inner peripheral surface of the cylindrical boss (56), an internal screw (57) is formed, into which the screw shaft piece (97) of the electrode terminal (91) can be screwed.
The positive current collector (50) is made of aluminum, and the negative current collector (50) is made of nickel.
[0023]
Manufacturing method After producing the battery can (1), electrode terminal mechanism (90), take-up electrode body (4) and current collector plate (50) shown in FIG. 1, the take-up electrode body (4) The cylindrical boss (56) of the current collector plate (50) is fitted into the central hole (40) of the core, and the core body formed at each end of the winding electrode body (4) as shown in FIGS. Press the current collector (50) against the edge (48). Here, when the cylindrical boss (56) of the current collector plate (50) is closely fitted in the central hole (40) of the winder electrode body (4), the current collector plate (50) for the winder electrode body (4) is obtained. ) Positioning is automatically performed.
[0024]
By pressing the current collector plate (50) against the core edge (48) of the winding electrode body (4) in this way, the arcuate convex portion (52) of the current collector plate (50) is shown in FIG. In this manner, the winding electrode body (4) bites into the core body edge (48), and a joining surface comprising a cylindrical surface is formed between the arc-shaped convex portion (52) and the core body edge (48). Further, as shown in FIG. 8, the cut-and-raised piece (53) of the current collector plate (50) bites deeply into the core body edge (48) of the winding electrode body (4), and the core body edge (48) and It will be crimped.
[0025]
In this state, as indicated by an arrow in FIG. 6, a laser beam is irradiated toward the inner peripheral surface of the arc-shaped convex portion (52) of the current collector plate (50) to perform laser welding. As a result, the arc-shaped convex part (52) of the current collector plate (50) and the core body edge (48) of the winding electrode body (4) are joined to each other with a large contact area, as shown in FIG. The pressure-bonded state between the cut and raised piece (53) and the core body edge (48) is maintained.
[0026]
Thereafter, the screw shaft piece (97) of the electrode terminal (91) is screwed into the inner screw (57) of the cylindrical boss (56) of the current collector plate (50), and the flange (92) of the current collector plate (50) is collected. Press contact is made with the surface of the flat body (51) of the electric plate (5).
After fixing the electrode terminals (91) and (91) to the current collector plates (50) and (50) at both ends of the winding electrode body (4) in this way, the winding electrode body (4) is shown in FIG. It accommodates in the inside of the cylinder (11) shown. Then, as shown in FIG. 1, after installing the lid (12) in each opening of the cylinder (11) and assembling the electrode terminal mechanism (90), the lid (12) is welded and fixed to the cylinder (11). To do.
Finally, after injecting the electrolyte into the battery can (1), the safety valve (13) is screwed into each lid (12) to complete the lithium ion secondary battery of the present invention.
[0027]
In the lithium-on secondary battery, the flange (92) of the electrode terminal (91) is in direct contact with the surface of the flat plate-like body (51) of the current collector plate (50) in a sufficiently large area and wound. Since the shortest distance current path from the collecting electrode body (4) through the current collector plate (50) to the electrode terminal (91) is formed, the electric resistance of the current path is small.
Further, the current collector plate (50) is joined to the core body edge (48) with a large contact area at each arc-shaped convex portion (52) and the welded portion of the core body edge (48), and the welding plate In the region other than the part, each cut-and-raised piece (53) bites into the core edge (48) and a good contact state is obtained, so that the current collector plate (50) and the winding electrode body (4) The contact resistance between them becomes small. However, since current is collected from the entire area of the core end edge (48) by the plurality of cut and raised pieces (53) formed on the current collecting plate (50), high current collecting performance can be obtained.
[0028]
However, the screw shaft piece (97) of the electrode terminal (91) and the cylindrical boss (56) of the current collector plate (50) are accommodated in the central hole (40) of the take-up electrode body (4) to collect the current. Since the structure for fixing the plate (50) to the electrode terminal (91) is provided using the dead space of the central hole (40), it is necessary to take extra space in the battery can (1). Accordingly, the output per unit volume of the secondary battery can be increased as compared with the conventional case.
[0029]
In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim. For example, the current collecting structure and the electrode terminal mechanism (90) of the present invention shown in FIG. 1 are not limited to the configuration provided at both ends of the winding electrode body (4), but one of the winding electrode bodies (4). A configuration in which the conventional current collecting structure and the electrode terminal mechanism (9) shown in FIG. 10 are provided at the end portion and the other end portion may be employed.
[Brief description of the drawings]
FIG. 1 is a partially cutaway front view of a secondary battery according to the present invention.
FIG. 2 is an exploded perspective view of a wound electrode body, a current collector plate, and electrode terminals.
FIG. 3 is a plan view of a current collector plate.
FIG. 4 is an enlarged cross-sectional view showing a main part of a current collector plate.
FIG. 5 is a perspective view of a step of pressing an arc-shaped convex portion of a current collector plate against a core body edge of a winding electrode body.
FIG. 6 is an enlarged cross-sectional view showing a state where an arc-shaped convex portion of a current collector plate is pressed against a core body edge of a winding electrode body.
FIG. 7 is a perspective view of a step of pressing a cut and raised piece of a current collector plate against an edge of a core body of a winding electrode body.
FIG. 8 is an enlarged cross-sectional view showing a state in which the cut and raised pieces of the current collector plate are pressed against the edge of the core body of the take-up electrode body.
FIG. 9 is a perspective view showing an appearance of a secondary battery.
FIG. 10 is a partially broken front view of a conventional secondary battery.
FIG. 11 is a partially developed perspective view of a wound electrode body.
[Explanation of symbols]
(1) Battery can
(11) Tube
(12) Lid
(4) Winding electrode body
(40) Central hole
(50) Current collector
(51) Flat body
(52) Arc-shaped convex part
(53) Cut and raised pieces
(56) Cylindrical boss
(57) Internal thread
(90) Electrode terminal mechanism
(91) Electrode terminal
(92) Flange
(97) Screw shaft piece

Claims (3)

Inside the battery can (1), a wound electrode body (4) wound in a spiral shape with a separator (42) interposed between a strip-like positive electrode (41) and a negative electrode (43) is accommodated. Each of (41) and negative electrode (43) is configured by applying an active material to the surface of the belt-like core body, and the electric power generated by the wound electrode body (4) can be taken out from a pair of electrode terminal portions. The edge (48) of the strip-shaped core constituting the positive electrode (41) or the negative electrode (43) protrudes from at least one end of the winding electrode body (4), and the edge (48 In the secondary battery in which the current collector plate (50) is installed and the current collector plate (50) is connected to one of the electrode terminal portions,
The current collector plate (50) is provided with a boss (56) that fits into the central hole (40) of the take-up electrode body (4). A secondary battery characterized in that the end protrudes and is fixed to the boss (56), and the end of the electrode terminal is pressed against the surface of the current collector plate (50) in the vicinity of the fixing position. . The one electrode terminal portion includes an electrode terminal (91) penetrating the battery can (1), and the electrode terminal (91) has a flange (92) to be pressed against the surface of the current collector (50). And a screw shaft piece (97) protruding from the flange (92) to the winding electrode body (4) side, and an inner screw on the inner peripheral surface of the boss (56) of the current collector plate (50) The secondary battery according to claim 1, wherein (57) is formed, and the screw shaft piece (97) is screwed into the inner screw (57). On the current collector plate (50), a plurality of arc-shaped convex portions (52) projecting in a circular arc shape toward the core body edge (48) are formed and directed toward the core body edge (48). A plurality of cut and raised pieces (53) cut and raised are formed, and in a state where these arcuate convex portions (52) and cut and raised pieces (53) are bitten into the edge (48) of the core body, The secondary battery according to claim 1 or 2, wherein the arc-shaped convex portion (52) is welded to the core body edge (48).

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