JP2006164714A - Non-aqueous electrolytic liquid secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous electrolytic liquid secondary battery capable of reducing electric resistance of a sealing plate. <P>SOLUTION: The non-aqueous electrolytic liquid secondary battery is constructed by housing an electrode body 4 impregnated with non-aqueous electrolytic liquid inside a battery can 1 in which a sealing plate 2 is caulked and fixed to the opening part of a bottomed cylinder 11. The sealing plate 2 has a three-layer structure in which a metal layer 23 of aluminum is interposed between a first metal plate 21 of nickel and a second metal plate 22 of aluminum and both metal plates 21, 23 are mutually welded and fixed. In the state where the sealing plate 2 is caulked and fixed at the opening part of the bottomed cylinder 11, the first metal plate 21 faces the outside of the battery can 1 and the second metal plate 22 faces the inside of the battery can 1. The metal layer 23 is formed by vapor-depositing aluminum on the face of the first metal plate 21 facing the second metal plate 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a non-aqueous electrolyte secondary battery configured by accommodating an electrode body serving as a power generation element inside a battery can formed by fixing a sealing plate to an opening of a bottomed cylindrical body.

  As shown in FIG. 5, the cylindrical lithium ion secondary battery is configured by accommodating a winding electrode body (4) inside a cylindrical battery can (1). The battery can (1) is formed by fixing a sealing plate (6) to an opening of a bottomed cylindrical body (11) serving as a negative electrode through an insulating member (13), and the sealing plate (6) includes a positive electrode. A terminal (25) is attached (see Patent Document 1 and Patent Document 2).

As shown in FIGS. 5 and 6, the sealing plate (6) has a two-layer structure in which a nickel plate (61) and an aluminum plate (62) are joined together, and the sealing plate (6) is a bottomed cylinder. The nickel plate (61) faces the outside of the battery can (1) and the aluminum plate (62) faces the inside of the battery can (1) in a state where it is caulked and fixed to the opening of the body (11). .
Further, a central hole (26) is opened in the nickel plate (61), and the internal pressure of the aluminum plate (62) exceeds a predetermined value in a region facing the central hole (26) of the nickel plate (61). A valve membrane (63) to be opened sometimes is formed.
The sealing plate (6) is configured by caulking and fixing a nickel plate (61) and an aluminum plate (62) to each other. The sealing plate (6) is formed to a thickness that can withstand the internal pressure of the battery. For example, in the case of a large battery having a diameter of 30 mm or more, the sealing plate (6) has a thickness of 1 to 2 mm or more. Will be formed.
JP 2000-90892 A [H01M 2/04] JP 2003-187773 A [H01M 2/12]

By the way, in a cylindrical lithium ion secondary battery, in order to perform charge / discharge at a high rate, a sealing plate having a small electric resistance is required.
However, in the conventional sealing plate (6), the nickel plate (61) and the aluminum plate (62) are merely joined together by caulking, so that the nickel plate (61) and the aluminum plate (62) are not connected. The contact resistance of the sealing plate (6) becomes large. As a result, there is a problem that the internal resistance of the battery is increased and charging / discharging at a high rate cannot be performed.

  As a method of solving this problem, there is a method of clad joining the nickel plate (61) and the aluminum plate (62). According to this method, since the joint area between the nickel plate (61) and the aluminum plate (62) is increased, the electrical resistance of the sealing plate is reduced. However, when the thickness of the nickel plate (61) and / or the aluminum plate (62) is increased, it becomes difficult to clad-join both, so for a large battery that requires a thickness of 1 to 2 mm or more. It was difficult to produce a sealing plate by clad bonding.

  As another structure of the sealing plate (6), a structure in which a nickel plate (61) and an aluminum plate (62) are joined by laser welding is known. According to this structure, the sealing plate for a large battery as described above can be produced by increasing the thickness of the nickel plate (61) and / or the aluminum plate (62). However, since the sealing plate produced by laser welding the nickel plate (61) and the aluminum plate (62) has poor weldability between aluminum and nickel, the nickel plate (61) and the aluminum plate (62) They are only welded together with a small joint area. Therefore, the electrical resistance of the sealing plate (6) is larger than the electrical resistance of the sealing plate produced by clad joining the nickel plate (61) and the aluminum plate (62). As a result, there is a problem that the internal resistance of the battery is increased and charging / discharging at a high rate cannot be performed.

  Therefore, an object of the present invention is to provide a non-aqueous electrolyte secondary battery that can reduce the electrical resistance of the sealing plate.

The nonaqueous electrolyte secondary battery according to the present invention is impregnated with a nonaqueous electrolyte inside a battery can (1) in which a sealing plate (2) is fixed to an opening of a bottomed cylindrical body (11). The electrode body (4) is accommodated, and the generated power of the electrode body (4) can be taken out from a pair of electrode terminal portions provided on the battery can (1). The sealing plate (2) is a laminate in which a metal layer (23) is interposed between a first metal plate (21) and a second metal plate (22), and the two metal plates (21) and (22) are fixed to each other by welding. The first metal plate (21) faces the outside of the battery can (1) while the second metal plate (22) faces the inside of the battery can (1).
The first metal plate (21) is made of a metal having higher strength than the second metal plate (22), and the second metal plate (22) is more resistant to corrosion by the non-aqueous electrolyte than the first metal plate (21). The metal layer (23) is formed of a metal of the same material as that of the other metal plate on the surface facing one of the other metal plates by a thin film forming method. Is formed.
Specifically, the sealing plate (2) is formed by laser welding or ultrasonic welding of the first metal plate (21) and the second metal plate (22) to each other.

In the nonaqueous electrolyte secondary battery of the present invention, the metal layer (23) is formed on the surface of one of the first metal plate (21) and the second metal plate (22). Is firmly bonded to the entire surface of the one metal plate. Further, since the metal layer (23) is made of the same metal as the other metal plate to be welded to the one metal plate, the other metal plate and the metal layer (23) are the same. Contact will be made between the material surfaces. As a result, the weldability between the first metal plate (21) and the second metal plate (22) is improved as compared with the prior art, and the first metal plate (21) and the second metal plate (22) 23) to be welded to each other with a large joint area. As a result, the electrical resistance of the sealing plate (2) becomes small.
The metal layer (23) can be formed by a well-known thin film forming method such as a vacuum deposition method, a CVD method, or a sputtering method.

Specifically, the sealing plate (2) has a thickness of 1 mm or more.
Conventionally, the electrical resistance of the sealing plate formed by welding the first metal plate (21) and the second metal plate (22) is the same as that of the first metal plate (21) and the second metal plate (22). The electric resistance of the sealing plate formed by clad bonding is larger than that of the sealing plate. However, according to the nonaqueous electrolyte secondary battery of the present invention, the first metal plate (21) and the second metal plate (22) are welded to each other with a large bonding area through the metal layer (23). Therefore, the electrical resistance of the sealing plate (2) is substantially equal to the electrical resistance of the sealing plate formed by clad joining the first metal plate (21) and the second metal plate (22). Furthermore, it is possible to produce a sealing plate for a large battery having a thickness of 1 to 2 mm or more, which has been difficult to produce by clad bonding, and this can increase the pressure resistance of the sealing plate.

  In a specific configuration, the first metal plate (21) is provided with a central hole (26), and the second metal plate (22) is opposed to the central hole (26) of the first metal plate (21). A valve membrane (24) to be released when the internal pressure exceeds a predetermined value is formed in the region where the pressure is applied.

Since the valve membrane (24) formed in the central part of the second metal plate (22) constituting the sealing plate (2) is formed thinner than other regions of the second metal plate (22), In some cases, the valve membrane (24) may be greatly distorted by heat generated during welding of the first metal plate (21) and the second metal plate (22). However, according to the nonaqueous electrolyte secondary battery of the present invention,
Since the metal layer (23) formed on one metal plate and the other metal plate are in contact with each other on the same material surface, between the first metal plate (21) and the second metal plate (22). Therefore, the first metal plate (21) and the second metal plate (22) can be welded with small energy. Therefore, when the second metal plate (22) on which the valve membrane (24) is formed and the first metal plate (21) are welded via the metal layer (23), a large distortion occurs in the valve membrane (24). There is no.

  The first metal plate (21) of the sealing plate (2) is made of a stainless steel, nickel, or iron core plated with nickel, and the second metal plate (22) is made of aluminum or an aluminum alloy. The metal layer (23) is made of aluminum or nickel.

  According to the nonaqueous electrolyte secondary battery of the present invention, it is possible to reduce the electrical resistance of the sealing plate, thereby enabling charge / discharge at a high rate.

Hereinafter, embodiments of the present invention applied to a cylindrical lithium ion secondary battery will be described in detail with reference to the drawings.
As shown in FIG. 1, a cylindrical lithium ion secondary battery according to the present invention has a winding electrode body (4) housed inside a cylindrical battery can (1). The sealing plate (2) is caulked and fixed to the opening of the bottomed cylindrical body (11) via a ring-shaped insulating member (13).
The battery can (1) has an outer diameter of 35 mm and a length of 100 mm.

As shown in FIGS. 1 and 2, the sealing plate (2) has a metal layer (23) made of aluminum between a first metal plate (21) made of nickel and a second metal plate (22) made of aluminum. It has a three-layer structure in which both metal plates (21) and (22) are laser welded to each other, and the first metal plate (21) and the second metal plate (22) have a disk shape.
The metal layer (23) is formed by depositing aluminum on one side of the first metal plate (21) by vapor deposition, and is firmly bonded to the entire surface of the first metal plate (21).

The first metal plate (21) faces the outside of the battery can (1) while the sealing plate (2) is caulked and fixed to the opening of the bottomed cylinder (11), and the second metal plate (22) Faces the inside of the battery can (1). A positive terminal (25) is attached to the surface of the first metal plate (21).
The first metal plate (21) has a circular central hole (26), and the second metal plate (22) has an internal pressure in a region facing the central hole (26) of the first metal plate (21). The valve membrane (24) to be opened when the value exceeds a predetermined value (0.98 to 1.18 MPa) is formed into a thin film by rolling the central portion of the second metal plate (22).

  As shown in FIG. 3, the wound electrode body (4) has a positive electrode (41) formed by applying a positive electrode active material (44) made of lithium cobalt oxide to the surface of a core body (45) made of an aluminum foil having a thickness of 15 μm. ), A negative electrode (43) obtained by applying a negative electrode active material (46) containing a carbon material to the surface of a core (47) made of a copper foil having a thickness of 10 μm, and an ion permeation impregnated with a nonaqueous electrolytic solution The separator (42) is made of a porous polypropylene microporous membrane, and 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. Yes. 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).

  A positive electrode current collector plate (51) having a lead portion (53) is laser-welded to an end edge (48) on the positive electrode (41) side of the winding electrode body (4), and the winding electrode body (4 The negative electrode current collector plate (52) is laser-welded to the edge (48) on the negative electrode (43) side of).

As shown in FIG. 1, the tip of the lead portion (53) of the positive electrode current collector plate (51) is welded to the back surface of the second metal plate (22) constituting the sealing plate (2). Further, the negative electrode current collector plate (not shown) is welded to the bottom surface of the bottomed cylindrical body (11).
Thereby, the electric power generated by the winding electrode body (4) can be taken out from the back surface of the positive electrode terminal (25) and the bottomed cylindrical body (11).

When producing the sealing plate (2), as shown in FIG. 4 (a), a metal layer (23) is formed on one side of the first metal plate (21), and then as shown in FIG. 4 (b). The first metal plate (21) and the second metal plate (22) are overlapped with each other with the metal layer (23) interposed therebetween. In this state, laser light is irradiated from the second metal plate (22) side along the circumference surrounding the central hole (26) of the first metal plate (21), and the first metal plate (21) and the first metal plate (21) Two metal plates (22) are laser welded to each other through a metal layer (23).
The diameter d of the first metal plate (21) and the second metal plate (22) is 33 mm. The thickness t1 of the first metal plate (21) is 1 mm, the thickness t3 of the second metal plate (22) is 0.5 mm, and the thickness t2 of the metal layer (23) is 100 μm.

  The sealing plate (2) can also be produced by ultrasonic welding. In this case, the first metal plate (21) and the second metal plate (22) are overlapped with each other across the metal layer (23), and the metal layer (23) and the second metal plate (22) are stacked. In close contact, ultrasonic waves are applied from the second metal plate (22) side along the circumference surrounding the central hole (26) of the first metal plate (21), and the first metal plate (21) and the first metal plate (21) Two metal plates (22) are ultrasonically welded to each other through a metal layer (23).

  As described above, since the second metal plate (22) and the metal layer (23) are in contact with each other on the same material surface, the weldability between the first metal plate (21) and the second metal plate (22) is improved. Improves than before. Thus, the first metal plate (21) and the second metal plate (22) are welded to each other with a large bonding area through the metal layer (23). As a result, the electrical resistance of the sealing plate (2) becomes small.

  Further, since the weldability is improved as described above, the first metal plate (21) and the second metal plate (22) can be welded with less energy than in the prior art. Accordingly, when the first metal plate (21) and the second metal plate (22) are welded via the metal layer (23), a thin-film valve membrane formed at the center of the second metal plate (22). There is no great distortion in (24).

  According to the non-aqueous electrolyte secondary battery of the present invention, the first metal plate (21) and the second metal plate (22) are welded with a large joining area via the metal layer (23). The electric resistance of the plate (2) is substantially equal to the electric resistance of the sealing plate formed by clad joining the first metal plate (21) and the second metal plate (22). Furthermore, it is possible to produce a sealing plate having a thickness of 1 to 2 mm or more, which has been difficult to produce by clad bonding, and this makes it possible to increase the pressure resistance of the sealing plate.

In order to confirm the effect of the present invention, two types of cylindrical lithium ion secondary batteries (Example and Comparative Example) were prepared by the method described later, and the resistance values of both batteries were compared.
EXAMPLE As shown in FIG. 3, a positive electrode (41) and a negative electrode (43) prepared by applying a positive electrode and a negative electrode active material (44) (46) to two cores (45) and (47), respectively, were separated into separators. (42) was sandwiched between them, and these were spirally wound to produce a wound electrode body (4).
In the production of the sealing plate (2) having a three-layer structure shown in FIG. 4 (b), first, aluminum is vapor-deposited on one surface of a 1 mm thick nickel plate (21) having a central hole (26). A metal layer (23) having a thickness of 100 μm was formed. Then, an aluminum plate (22) having a thickness of 0.5 mm on which the valve membrane (63) is formed is superposed on one surface of the nickel plate (21) on which the metal layer (23) is formed, and the metal layer (23) is interposed therebetween. The aluminum plate (22) and the nickel plate (21) were laser welded together to produce the sealing plate (2).

As shown in FIG. 3, the positive electrode current collector plate (51) made of aluminum is laser-welded to the positive electrode side edge (48) of the winding electrode body (4), and the negative electrode side of the winding electrode body (4) A nickel negative electrode current collector plate (52) was laser welded to the edge (48). Then, as shown in FIG. 1, the winding electrode body (4) to which the positive electrode current collecting plate (51) and the negative electrode current collecting plate (52) are welded is accommodated in the bottomed cylindrical body (11), and the negative electrode current collecting plate is accommodated. The electric plate (52) was resistance welded to the bottom surface of the bottomed cylindrical body (11), and the lead portion (53) of the positive electrode current collector plate (51) was resistance welded to the back surface of the sealing plate (2).
Furthermore, after injecting the electrolyte into the bottomed cylinder (11) from the opening of the bottomed cylinder (11), as shown in FIG. 1, the insulating member (13 ) To fix the sealing plate (2) by caulking, to produce a cylindrical lithium ion secondary battery of the example.

Comparative Example As shown in FIG. 5, a 1 mm thick nickel plate (61) having a central hole (26) and a 0.5 mm thick aluminum plate (62) on which a valve membrane (63) was formed were stacked. In the same manner as in the Example, except that the aluminum plate (62) and the nickel plate (61) were laser welded to produce a two-layer sealing plate (6). A secondary battery was produced.

Battery Resistance Measurement The battery resistance value at a frequency of 1 kHz in Examples and Comparative Examples was measured.
The results of resistance measurement are shown in Table 1 below.

As is apparent from the measurement results, it can be seen that the lithium ion secondary batteries of the examples have lower resistance values and improved charge / discharge performance than the lithium ion secondary batteries of the comparative examples.
This is because the three-layered sealing plate produced by vapor-depositing aluminum on one side of the nickel plate is compared with the two-layered sealing plate produced without vapor-depositing aluminum. The junction area is large, which results in low resistance.
Therefore, according to the non-aqueous electrolyte secondary battery of the present invention, the resistance of the battery can be reduced, and thereby high charge / discharge performance can be obtained.

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, in the present embodiment, an aluminum metal layer (23) is deposited on the surface of the first metal plate (21) made of nickel facing the second metal plate (22). It is also possible to adopt a configuration in which a nickel vapor deposition layer is formed on the surface of the second metal plate (22) made of the second metal plate (22) facing the first metal plate (21).
The metal layer (23) is formed by vapor deposition, but may be formed by other well-known thin film forming methods such as sputtering.
Furthermore, the first metal plate (21) is made of nickel, and the second metal plate (22) is made of aluminum. However, the first metal plate (21) is made of stainless steel or an iron core with nickel plating. The second metal plate (22) may be formed from an aluminum alloy.

It is sectional drawing of the cylindrical lithium ion secondary battery of this invention. It is an expanded sectional view which shows the principal part of FIG. It is a partial expansion perspective view of a winding electrode body. It is sectional drawing which shows the structure of a sealing board. It is sectional drawing of the conventional cylindrical lithium ion secondary battery. It is an expanded sectional view which shows the principal part of FIG.

Explanation of symbols

(1) Battery can
(11) Bottomed cylinder
(2) Sealing plate
(21) First metal plate
(22) Second metal plate
(23) Metal layer
(24) Valve membrane
(26) Central hole
(4) Winding electrode body
(51) Positive current collector
(52) Negative current collector

Claims (5)

  An electrode body (4) impregnated with a non-aqueous electrolyte is accommodated in a battery can (1) formed by fixing a sealing plate (2) to an opening of a bottomed cylindrical body (11). In the non-aqueous electrolyte secondary battery in which the electric power generated by the electrode body (4) can be taken out from a pair of electrode terminal portions provided on the sealing plate (2), the sealing plate (2) includes the first metal plate (21) and the second metal plate (21). It has a laminated structure in which a metal layer (23) is interposed between metal plates (22) and both metal plates (21) and (22) are fixed to each other by welding. The first metal plate (21) is a battery can (1). The second metal plate (22) faces the inside of the battery can (1), and the first metal plate (21) is made of a metal having higher strength than the second metal plate (22). The second metal plate (22) is made of a metal having a higher corrosion resistance to the non-aqueous electrolyte than the first metal plate (21), and the metal layer (23) is the other of the metal plates. On the surface facing the other metal plate, the same metal material as the other metal plate is thinned. Non-aqueous electrolyte secondary battery, characterized by being formed by forming a forming method.   The non-aqueous electrolyte secondary according to claim 1, wherein the sealing plate (2) is configured by laser welding or ultrasonic welding of the first metal plate (21) and the second metal plate (22) to each other. battery.   The nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein the sealing plate (2) has a thickness of 1 mm or more.   The first metal plate (21) has a central hole (26), and the second metal plate (22) has an internal pressure in a region facing the central hole (26) of the first metal plate (21). The non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein a valve membrane (24) to be released when the value exceeds a predetermined value.   The first metal plate (21) of the sealing plate (2) is made of a stainless steel, nickel or iron core plated with nickel, and the second metal plate (22) is made of aluminum or an aluminum alloy. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the metal layer (23) is made of aluminum or nickel.

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