JPH11195412A - Internal electrode terminal for sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb the vertical wave energy generated in ultrasonic welding and suppress the vibration of an internal electrode terminal by the vertical wave to prevent the rupture of the internal electrode terminal by providing, in the internal electrode terminal, a vertical wave absorbing part for absorbing the vertical wave generated in the ultrasonic welding of an electrode lead. SOLUTION: The internal electrode terminal 9 of an electrolyte built-in type lithium secondary battery has a three-dimensional structure consisting of a plate 91 having a through-hole 93 and a cylinder body 92 integrally fixed to the periphery of the plate body 91. The vicinity of the integrally fixed part 94 of the plate 91 and the cylinder 92 functions as a vertical wave absorbing part. The tip of a positive electrode lead 32 is ultrasonically welded onto the inner side wall of the cylinder 92. Since the ultrasonic vertical wave in the ultrasonic welding of the positive electrode lead 32 onto the inner side wall of the cylinder 92 is effectively absorbed in the fixed position 94, the plate 91 can be protected from the breakage by ultrasonic vertical wave.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal electrode terminal for a sealed battery, and more particularly to various secondary batteries having an electrolyte.
For example, the present invention relates to an internal electrode terminal suitable for use in a lithium secondary battery with a built-in electrolyte.

[0002]

2. Description of the Related Art FIG. 4 is a conceptual cross-sectional view of a conventional lithium secondary battery with a built-in electrolyte, and FIG. 5 is a detailed cross-sectional view of a positive electrode cover 5 and its vicinity in FIG. 6 is a detailed sectional view of another positive electrode cover 5 in FIG. 4 and the vicinity thereof, and FIG. 7 is a detailed partial sectional view of still another positive electrode cover 5 in FIG. 4 to 7, 1 is an iron battery can, 2 is a negative electric insulating plate, 3 is a power generating element, 31 is a negative electrode lead extending from the lower part of the power generating element 3, and 32 is an upper part of the power generating element 3 4 is a donut-shaped positive electrical insulating plate, 5 is a positive electrode lid having a battery safety structure, and 6 is an external positive electrode lid case integrally formed with the battery can 1 on the upper part of the battery can 1. Reference numeral 7 denotes an electrically insulating gasket for insulating the positive electrode lid 5 from the external positive electrode lid case 6, and 8 denotes an aperture provided on the wall of the battery can 1 to divide the battery can 1 from the positive electrode lid case 6.

In FIG. 5, a positive electrode cover 5 is provided with a gas vent hole 5.
Positive electrode cap 51 having a donut-shaped PTC
(Positive temperature coefficient) It is composed of a plate 52 and a rupture plate 53 having a weak point 531. A gas storage space 512 exists between the positive electrode cap 51 and the rupture plate 53. On the back of the rupture plate 53,
The distal end of the positive electrode lead 32 extending from the power generating element body 3 through the center hole of the positive electrode electrical insulating plate 4 is welded. The positive electrode cover 5 is hermetically fixed to the upper part of the battery can 1 by the caulking force of the external positive electrode cover case 6 together with the external electric insulating gasket 7.

In FIG. 6, a positive electrode cap 5 comprising a positive electrode cap 51, a donut-shaped PTC plate 52, and a rupture plate 53 is hermetically held by the caulking force of a positive electrode cover case 6 'together with an electrically insulating gasket 7'. Further, as shown in the figure, the external positive electrode cover case 6 and the external electric insulating gasket 7 are fixed to the upper portion of the battery can 1 in an airtight manner by the caulking force of the case 6.

When manufacturing a lithium battery with a built-in electrolyte shown in FIG. 6, a positive electrode cap 51, a PTC plate 52,
The positive cover 5 comprising the rupture plate 53 and the rupture plate 53 is assembled by caulking the positive cover case 6 'with the electrical insulating gasket 7' interposed therebetween to assemble the sub-assemblies comprising these members in a separate process. Is guided together with the external electric insulating gasket 7 to the upper end portion of the battery can 1 which becomes the external positive electrode lid case 6, and the upper end portion is crimped together with the electric insulating gasket 7. Thus, a lithium secondary battery having the structure shown in FIG. 6 can be manufactured.

Recently, from the standpoint of placing greater emphasis on the safety of a lithium secondary battery with a built-in electrolyte, when the internal pressure of the battery suddenly rises due to an abnormal situation, the rupture plate 53 and the positive electrode lead 32 are ruptured before the rupture plate 53 bursts. It has been recognized that there is a need to quickly cut off the electrical connection with the device, and various improvements have been made to realize such an early cut-off. For example, instead of welding the positive electrode lead 32 directly to the back surface of the rupture plate 53, as shown in FIG.
3 is recessed to form a recess 532, while the lower member 61 ′ of the positive electrode lid case 6 ′ is expanded to expand the upper surface of the expanded lower member 61 ′ and the back surface of the recess 532. And the positive electrode lead 32 is welded to the back surface of the lower member 61 '. That is, the lower member 61 '
Functions as an internal electrode terminal of the battery. 611 '
This is a through hole provided in the lower member 61 '. When the sub-assembly is formed as described above, when the internal pressure of the battery rises, the internal pressure acts directly on the rupture plate 53 through the through hole 611 ′. For this reason, only the rupture plate 53 expands without deforming the lower member 61 ′ of the positive electrode lid case 6 ′, and the above-mentioned spot welded portion is broken, so that the electrical connection between the rupture plate 53 and the lower member 61 ′ is made. The conduction is interrupted, and the electrical conduction between the rupture plate 53 and the positive electrode lead 32 is interrupted. The positive electrode lead 32 is usually made of aluminum, and the positive electrode lid case 6 'is also usually made of aluminum so that welding with the aluminum positive electrode lead 32 is easy.

The welding of the electrode leads to the internal electrode terminals of the battery such as the lower member 61 'is mainly performed by ultrasonic welding which is excellent in welding speed and welding stability. In this case, a longitudinal wave is generated to vibrate the internal electrode terminal, and this vibration often causes a new problem that the terminal is broken. This breaking problem is particularly remarkable when the internal electrode terminals are generally made of aluminum having low mechanical strength.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an internal electrode terminal for a sealed battery in which the above-mentioned breakage problem when the electrode lead is ultrasonically welded to the internal electrode terminal is solved. And

[0009]

The present invention is characterized by having the following means in order to solve the above-mentioned problems. (1) For a sealed battery, which has a longitudinal wave absorbing portion capable of preventing breakage of the internal electrode terminal due to longitudinal waves generated during ultrasonic welding when the electrode lead is ultrasonically welded to the internal electrode terminal. Internal electrode terminal. (2) The internal electrode terminal for a sealed battery according to the above (1), wherein both the internal electrode terminal and the electrode lead are made of an aluminum-based metal. (3) The sealed battery according to (2), wherein the aluminum-based metal is at least one selected from the group consisting of pure aluminum having a purity of 99% by weight or more and hard aluminum having an aluminum content of at least 70% by weight. Internal electrode terminals. (4) The internal electrode terminal is a flat plate, and the longitudinal wave absorbing portion is provided substantially continuously between the plane center and the edge of the flat plate and so as to surround the center (1). The internal electrode terminal for a sealed battery according to any one of (1) to (3). (5) The longitudinal wave absorbing portion is formed of an elongated portion formed by cutting out a part of the flat plate, and the elongated portion is not parallel to the traveling direction of the longitudinal wave (1)-(4) An internal electrode terminal for a sealed battery according to any one of the above. (6) The sealed type according to any one of (1) to (3), wherein the longitudinal wave absorbing portion includes a surface of the internal electrode terminal portion having an angle of at least 30 degrees with respect to a plane where the longitudinal wave travels. Internal electrode terminals for batteries. (7) The internal electrode terminal is composed of a flat plate and a tubular body integrally fixed to the periphery of the flat plate body, and the integrally fixed portion of the flat plate and the tubular body functions as a longitudinal wave absorbing portion, and The internal electrode terminal for a sealed battery according to the above (6), wherein the electrode lead is ultrasonically welded on a wall surface of the cylindrical body. (8) The interior for a sealed battery according to any one of (1) to (7) above, wherein the longitudinal wave absorbing portion is capable of absorbing at least 50% of longitudinal wave energy generated during ultrasonic welding. Electrode terminal. (9) The above (1) to (1) to
The internal electrode terminal for a sealed battery according to any one of (8) and (9).

[0010]

The internal electrode terminal for a sealed battery according to the present invention has a longitudinal wave absorbing portion, so that the presence of the longitudinal wave absorbing portion absorbs longitudinal wave energy generated at the time of ultrasonic welding. Prevents electrode terminals from breaking.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the constituent materials of the internal electrode terminals are not particularly limited. In the case of a lithium secondary battery with a built-in electrolyte, the electrode leads to be ultrasonically welded are generally made of aluminum. Therefore, it is preferable to use an aluminum-based metal which is easily welded thereto, for example, pure aluminum having a purity of 99% by weight or more, and hard aluminum having an aluminum content of at least 70% by weight. Further, among the aluminum-based metals, it is preferable to select and use a particularly convenient aluminum-based metal depending on the structure of the aluminum internal electrode terminal, as described in the embodiments described later.

The waves generated during ultrasonic welding are mainly longitudinal waves, ie, compressional waves. Therefore, the longitudinal wave absorbing portion in the present invention has a function of attenuating or absorbing longitudinal wave energy generated during ultrasonic welding, and particularly absorbs at least 50%, particularly at least 80% of longitudinal wave energy generated. Those having the function of obtaining are preferred.

The structure of the longitudinal wave absorbing portion may be arbitrary as long as it has a function of preventing breakage of the internal electrode terminal due to longitudinal waves generated during ultrasonic welding. When the internal electrode terminal is a flat plate, the longitudinal wave travels along the plane of the plate, so that the longitudinal wave absorbing portion is in a direction non-parallel to the traveling direction of the longitudinal wave, for example, perpendicular to the traveling direction. In a direction or a tilting direction, for example, like a ring-shaped elongated portion 99 in the embodiment of FIGS. 2 to 3 described later, the flat plate extends in a direction perpendicular to the traveling direction of the longitudinal wave and receives the longitudinal wave. A structure having a portion which can flexibly vibrate in the radial direction, or a three-dimensional structure comprising a flat plate as an internal electrode terminal and a cylindrical body integrally fixed to the periphery of the flat plate as in the embodiment of FIG. May be used. In this case, the integral fixing portion between the flat plate and the cylinder functions as a longitudinal wave absorbing portion. Therefore, when an internal electrode terminal having such a three-dimensional structure is used, the electrode lead is welded to a body part (for example, the above-mentioned cylindrical body) different from a body part (for example, the above-mentioned flat body) to be protected from breaking due to longitudinal waves. Good to do. Then,
The longitudinal wave traveling along the surface of the cylindrical body is absorbed by the longitudinal wave absorbing portion at the fixing point, and the flat body is protected from breaking by the longitudinal wave. In general, when the internal electrode terminal has a three-dimensional structure as shown in FIG. 1, a portion including the surface of the internal electrode terminal portion having an angle with respect to a plane in which the longitudinal wave travels, particularly an angle of at least 30 degrees (for example, The flat plate and the cylindrical body bent at an angle of 90 degrees around the fixing point 94 in FIG. 1) have an action of absorbing longitudinal waves. Therefore, in the present invention, such a portion may be used as a longitudinal wave absorbing portion.

The position of the longitudinal wave absorbing portion is generally between a portion where the internal electrode terminal is easily broken and a welding portion of the electrode lead (longitudinal wave generation source), but the internal electrode terminal is a flat plate. In some cases, it is effective in many cases to provide a longitudinal wave absorbing portion substantially continuously between the center and the edge of the flat body and surrounding the center.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial cross-sectional view of an electrolyte-containing lithium secondary battery having internal electrode terminals according to an embodiment of the present invention. FIG.
FIG. 3 is a partial cross-sectional view of an electrolyte-containing lithium secondary battery having internal electrode terminals according to another embodiment of the present invention, and FIG. 3 is a reduced plan view of FIG.

In the following, FIG. 1 to FIG.
This will be described with reference to a normal electrolyte-containing lithium secondary battery shown in FIG. 1 to 3, 1 is an iron battery can, 32 is a positive electrode lead extending from the upper part of the power generating element body 3, 5 is a positive electrode lid having a battery safety structure, and 6 is a battery can 1
, An external positive cover case integrally formed with the battery can 1, an external electrically insulating gasket 7 for insulating the positive cover 5 from the external positive cover case 6, 8 provided on a wall of the battery can 1, This is an aperture that separates the battery can 1 from the external positive electrode lid case 6.

The positive electrode cover 5 has a positive electrode cap 51 having a gas vent hole 511, a donut-shaped PTC plate 52, and a rupture plate 53 having a weak point 531 and a depression 532.
And a positive electrode lid case 6 'via an electrically insulating gasket 7'.
It is fixed integrally by swaging. As shown in the figure, the positive electrode cap 51 and the positive electrode lid case 6 'are formed integrally. Reference numeral 9 denotes an aluminum internal electrode terminal as an embodiment of the present invention, 10 denotes an aluminum reinforcing plate for reinforcing the internal electrode terminal 9, and 11 denotes an electric insulating sheet. The electric insulating sheet 11, the reinforcing plate 10, and the internal electrode terminals 9 are connected to the ring-shaped protrusions 7 of the electric insulating gasket 7 '.
1 ′ holds the back surface of the rupture plate 53.

The material for forming the positive electrode cover case 6 ′ is a metal material having high mechanical strength, for example, at least about 1.5 of aluminum which has conventionally been used as a material for forming the positive electrode cover case 6 ′ in terms of elastic modulus. Times, especially at least about 3 times, or the elastic modulus is 15,000 to
About 25,000 kg / mm ² , for example, SUS
(Stainless steel), carbon steel, nickel, and the like. Especially, SUS is preferred. The positive electrode cap 51
It is formed of a conventionally known conductive metal material such as iron and SUS. Therefore, it is particularly preferable that the positive electrode lid case 6 ′ and the positive electrode cap 51 are integrally formed of a conductive metal material having high mechanical strength such as SUS.

In FIG. 1, an internal electrode terminal 9 has a through hole 9
3 has a three-dimensional structure composed of a flat plate 91 having a 3 and a cylindrical body 92 integrally fixed to the periphery of the flat plate 91. In that case, the vicinity of the integral fixing point 94 between the flat plate 91 and the cylinder 92 functions as a longitudinal wave absorbing portion, and the tip of the positive electrode lead 32 is welded on the inner side wall of the cylinder 92. Therefore,
The longitudinal wave of the ultrasonic wave when the positive electrode lead 32 is welded on the inner side wall of the cylindrical body 92 is effectively absorbed at the fixing point 94, so that the flat plate body 91 is protected from breaking. The flat body 91 of the internal electrode terminal 9 is provided on the back surface of the reinforcing plate 10 and substantially at the center of the upper surface thereof.
2 is spot-welded to the back surface.

When assembling the electrolyte-containing lithium secondary battery shown in FIG. 1, the positive electrode cover 5 is guided to the upper end portion of the battery can 1 which is to be the outer positive electrode cover case 6 so that the power generating element 3 The tip of the positive electrode lead 32 extending from the upper portion is ultrasonically welded onto the inner side wall of the cylindrical body 92 of the internal electrode terminal 9,
Next, the upper end of the battery can 1 is caulked via the external electrically insulating gasket 7 to form the external positive electrode lid case 6 and the positive electrode lid 5 is set in the external positive electrode lid case 6.

When welding the positive electrode lead 32 on the inner side wall of the cylindrical body 92 of the internal electrode terminal 9, vibration of the ultrasonic welding machine is performed with a suitable pressure receiving means (anvil) installed outside the battery can 1. Since it is possible to perform welding while firmly pressing the part of the child (horn) against the welding location, extremely stable ultrasonic welding is generally possible regardless of the type of aluminum forming the internal electrode terminal 9. . Therefore, in such a case, as a material for forming the internal electrode terminal 9, ultrasonic welding is easy, but the ultrasonic weldability is somewhat inferior to pure aluminum, but mechanical strength is better than pure aluminum, which is poor in mechanical strength. Hard aluminum is more preferable.

The flat plate 91 of the internal electrode terminal 9 has a through hole 93.
Since the reinforcing plate 10 also has the through-hole 101, the pressure in the battery passes directly through the through-holes 93 and 101 to the rupture plate 53. Therefore, even if an abnormality occurs in the battery and the pressure inside the battery rises, the internal electrode terminals 9 are not deformed by the through holes 93 and the reinforcing plate 10, while the rupture plate 53 is deformed in the expanding direction. The spot welding is broken and the electrical conduction between the two is effectively cut off. Further, the rupture plate 53 is ruptured by a predetermined high pressure, and the high pressure inside the battery is reduced by the positive electrode cap 51.
The battery escapes from the vent hole 511 provided in the battery to prevent the battery from exploding.

The lithium secondary battery with a built-in electrolyte shown in FIGS. 2 and 3 differs from that shown in FIG. 1 only in the structure of the internal electrode terminals 9. The tip of the positive electrode lead 32 is welded to the back surface near the edge of the flat plate 91. Flat body 91
Has two substantially semicircular notches 96 except for two non-notches 95 (hereinafter, see FIG. 3), and two non-notches 96 inside the notch 96. It has two substantially semicircular notches 98 except for the notch 97. As a result, a ring-shaped elongated portion 99 is formed between the notched portions 96 and 98, and the elongated portion 99 is held by two non-cut portions 95 and two non-notched portions 97. Have been. The ring-shaped elongated portion 99 is effectively non-parallel to the traveling direction of the longitudinal wave regardless of the position of the longitudinal wave generating source, and thus effectively functions as a longitudinal wave absorbing portion.

When the positive electrode lead 32 is welded to the back surface of the flat body 91 of the internal electrode terminal 9 shown in FIGS.
It is necessary to install pressure receiving means on the outer surface of the
Since the outer surface of the electrode has a complicated shape and the positive electrode lid 5 itself has a somewhat soft structure, there is a possibility that the pressure receiving effect of the pressure receiving means is poor and the pressing force of the ultrasonic welding machine against the welding point becomes insufficient. is there. In such a case, the internal electrode terminal 9 (the flat plate 9
1) is preferably formed of pure aluminum which is easy to weld.

[0025]

The internal electrode terminal for a sealed battery according to the present invention can be ultrasonically welded to an electrode lead without breaking it, so that various types of secondary batteries, in particular, electromotive force and discharge capacity can be obtained. It is particularly suitable for an electrolyte-containing lithium secondary battery having excellent performance.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of an electrolyte-containing lithium secondary battery having internal electrode terminals according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of an electrolyte-containing lithium secondary battery having internal electrode terminals according to another embodiment of the present invention.

FIG. 3 is a reduced plan view of FIG. 2;

FIG. 4 is a conceptual cross-sectional view of a general lithium secondary battery with a built-in electrolytic solution.

FIG. 5 is a detailed cross-sectional view of a positive electrode lid 5 and its vicinity in FIG.

FIG. 6 is a detailed cross-sectional view of another positive electrode cover 5 and its vicinity in FIG.

FIG. 7 is a detailed partial cross-sectional view of still another positive electrode lid 5 in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery can 3 Power generation element body 32 Positive electrode lead 5 Positive electrode cover 53 Rupture plate 9 Internal electrode terminal 91 Flat body of internal electrode terminal 92 Cylindrical body of internal electrode terminal 94 Fixed part which functions as a longitudinal wave absorption part 99 As a longitudinal wave absorption part Slender part that works

Claims (9)

[Claims] 1. A sealed battery having a longitudinal wave absorbing portion capable of preventing breakage of an internal electrode terminal due to a longitudinal wave generated during ultrasonic welding when an electrode lead is ultrasonically welded to an internal electrode terminal. Internal electrode terminals. 2. The internal electrode terminal for a sealed battery according to claim 1, wherein both the internal electrode terminal and the electrode lead are made of an aluminum-based metal. 3. An aluminum-based metal having a purity of 99% by weight.
3. The internal electrode terminal for a sealed battery according to claim 2, wherein the pure aluminum and the aluminum content are at least one selected from the group consisting of hard aluminum having at least 70% by weight. 4. The internal electrode terminal is a flat plate, and the longitudinal wave absorbing portion is provided substantially continuously between the plane center and the edge of the flat plate and surrounding the center. 1
4. The internal electrode terminal for a sealed battery according to any one of claims 1 to 3. 5. The longitudinal wave absorbing portion comprises an elongated portion formed by cutting a part of a flat plate, and the elongated portion is non-parallel to a traveling direction of the longitudinal wave. An internal electrode terminal for a sealed battery according to the item (1). 6. The sealed battery according to claim 1, wherein the longitudinal wave absorbing portion includes a surface of the internal electrode terminal portion having an angle of at least 30 degrees with respect to a plane in which the longitudinal wave travels. Internal electrode terminals. 7. The internal electrode terminal comprises a flat plate and a tubular body integrally fixed to a peripheral edge of the flat plate, and a fixed portion of the flat plate and the tubular body integrally functions as a longitudinal wave absorbing portion. 7. The internal electrode terminal for a sealed battery according to claim 6, wherein the electrode lead is ultrasonically welded on a wall surface of the cylindrical body. 8. The internal electrode for a sealed battery according to claim 1, wherein the longitudinal wave absorbing portion is capable of absorbing at least 50% of the energy of longitudinal waves generated during ultrasonic welding. Terminal. 9. The internal electrode terminal for a sealed battery according to claim 1, wherein the internal electrode terminal is for an electrolyte-containing lithium secondary battery.