JP2007194065A - Sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an internal short circuit between a cover and an output terminal caused by lithium metal even if the lithium metal deposits on the inner surface and the output terminal. <P>SOLUTION: A sealed battery contains a cylindrical battery can 1 with bottom whose top surface is opened, an electrode body 2 having a positive electrode 11, a negative electrode 12, and housed in the battery can 1, a cover 3 sealing the opening top surface of the battery can 1, an output terminal 7 to which the positive electrode 11 is connected, and a terminal fitting hole 9 formed in the cover 3 and to which the output terminal 7 is fit through an insulating gasket 6 so as to pass through. The lower part of the output terminal 7 is exposed to the inside of a battery. The insulating gasket 6 has an insulating part 6a insulating the output terminal 7 from the cover 3, and a shielding part 6b extending from the insulating part 6a to the lower part and surrounding the lower part of the output terminal 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sealed battery such as a lithium primary battery using lithium metal or a lithium alloy as a negative electrode active material.

  In the lithium primary battery, as shown in Patent Document 1, an electrode body is formed by spirally winding a separator between a positive electrode and a negative electrode, and the electrode body is accommodated in a battery can. A structure that is sealed with a lid is known.

  In the lithium primary battery, a terminal attachment hole is provided in the lid, and an output terminal is attached to the terminal attachment hole in a penetrating manner through an insulating gasket. Then, the output terminal is connected to the positive electrode potential by connecting the output terminal and the positive electrode of the electrode body by the current collecting lead. On the other hand, the negative electrode of the electrode body is connected to the inner surface of the battery can, and the lid is at the negative electrode potential through the battery can.

  This type of lithium primary battery has a higher energy density and can be used for a long period of time as compared with an alkaline battery and the like.

JP-A-1-239769 (FIG. 1) Japanese Patent Laid-Open No. 5-41248 (FIG. 1) Japanese Patent Laid-Open No. 5-109435 (FIG. 1)

  In the lithium primary battery, when it is accidentally charged, a current flows in a direction opposite to the original discharge current. Further, when an old battery having a reduced discharge capacity and a new battery are mixed and used, a current flows from the new battery to the old battery in a direction opposite to the original discharge current. In these cases, particulate lithium metal may be deposited on the inner surface of the lid that becomes the potential of the negative electrode, and the lithium metal may grow and contact the output terminal, causing an internal short circuit.

  Patent Documents 1 to 3 disclose means for preventing an internal short circuit caused by the deposition of lithium metal. However, in Patent Document 1, the short circuit between the entire outer periphery and lower surface periphery of the electrode body and the inner surface of the battery can is prevented only by the insulating film. In Patent Document 2, only the separator prevents lithium metal from getting over the separator and short-circuited to the positive electrode, and in Patent Document 3, only insulating metal prevents lithium metal from getting over the separator.

  That is, Patent Documents 1 to 3 do not pay attention to the deposition of lithium metal on the inner surface of the lid, which is the potential of the negative electrode, and the lithium metal deposited on the inner surface of the lid contacts the output terminal and causes an internal short circuit. There is a problem where this cannot be prevented.

  Further, in a battery in which the negative electrode of the electrode body is connected to the output terminal and the positive electrode of the electrode body is connected to the inner surface of the battery can, lithium metal is deposited below the output terminal. And the output terminal may be internally short-circuited.

  Accordingly, an object of the present invention is to provide a sealed battery in which, even if lithium metal is deposited on the inner surface of the lid or the output terminal, the lid and the output terminal are not internally short-circuited by the lithium metal.

  As shown in FIG. 2, the sealed battery targeted by the present invention has a bottomed cylindrical battery can 1 having an open top, a positive electrode 11, and a negative electrode 12, and is an electrode accommodated in the battery can 1. Body 2, lid 3 that covers the upper surface of battery can 1, output terminal 7 to which either positive electrode 11 or negative electrode 12 is connected, and output terminal 7 formed on lid 3 via insulating gasket 6 Including a terminal attachment hole 9 attached in a penetrating manner, and the lower portion of the output terminal 7 is exposed in the battery.

  In the present invention, as shown in FIG. 1, the insulating gasket 6 includes an insulating portion 6 a that insulates the output terminal 7 from the lid 3, and a shielding portion 6 b that extends downward from the insulating portion 6 a and surrounds the lower portion of the output terminal 7. is doing.

  Specifically, the electrode body 2 is formed by winding a separator 13 between a strip-shaped positive electrode 11 and a strip-shaped negative electrode 12, and the negative electrode active material of the negative electrode 12 is lithium metal. Alternatively, a lithium alloy is used.

  In such a battery, a flat insulating plate 5 is disposed on the upper side of the electrode body 2, and the lower end of the shielding portion 6 b of the insulating gasket 6 is in contact with the insulating plate 5 to restrict the upward movement of the electrode body 2. Can be.

  A holding plate 10 is arranged below the insulating portion 6 a of the insulating gasket 6, and the output terminal 7 is fixed to the periphery of the terminal mounting hole 9 through the holding plate 10 and the insulating portion 6 a of the insulating gasket 6. Thus, the shielding part 6 b of the insulating gasket 6 can surround the lower part of the output terminal 7 and the pressing plate 10.

  Moreover, in the shielding part 6b of the insulating gasket 6, as shown in FIG. 3, the lower part of the output terminal 7 and the pressing plate 10 may be covered with an insulating material. Insulating material here includes insulating paint 23 and the like, and as the material of insulating material, UV curable resin, rubber resin, vinylidene fluoride (PVDF) resin, water glass (sodium silicate solution) ).

  According to the present invention, since the shielding portion 6b of the insulating gasket 6 surrounds the lower portion of the output terminal 7, even if lithium metal or the like is deposited on the lower portion of the output terminal 7 or the inner surface of the lid 3, the deposited lithium metal or the like An internal short circuit is prevented from occurring between the output terminal 7 and the lid 3, and the reliability of the battery is improved accordingly.

  In addition, since the insulating gasket 6 used in the conventional battery is provided with the shielding portion 6b, a member for surrounding the lower portion of the output terminal 7 is formed separately from the insulating gasket 6 so that the output terminal 7, the lid 3, etc. There is no need to assemble it. That is, it is possible to prevent an internal short circuit due to the deposited lithium metal or the like without adding a new operation when assembling the battery.

  When the shielding portion 6b of the insulating gasket 6 restricts the upward movement of the electrode body 2, the shielding portion 6b of the insulating gasket 6 is effectively used, and the positive electrode of the electrode body 2 due to an impact when the battery is accidentally dropped. 11 and the negative electrode 12 can be prevented from coming into contact with the output terminal 7 and the lid 3 and short-circuiting.

  By surrounding the pressing plate 10 together with the lower portion of the output terminal 7 with the shielding portion 6b of the insulating gasket 6, an internal short circuit between the pressing plate 10 and the lid 3 can be prevented, and the reliability of the battery is improved in this respect as well.

  When the lower part of the output terminal 7 and the pressing plate 10 are covered with an insulating material, an internal short circuit due to the deposited lithium metal or the like can be reliably prevented. Moreover, for example, after the output terminal 7, the insulating gasket 6 and the pressing plate 10 are attached to the lid 3, the insulating material is placed in the shielding portion 6b with the shielding portion 6b of the insulating gasket 6 facing upside down. Since the lower portion of the output terminal 7 and the pressing plate 10 can be covered with an insulating material simply by pouring and solidifying into a semi-solid or solid state, the covering operation can be easily performed.

(Example 1) FIG. 1 and FIG. 2 show Example 1 of a sealed battery targeted by the present invention, and as shown in FIG. 2, a bottomed cylindrical battery can 1 having an upper surface opened, and a battery An electrode body 2 and a non-aqueous electrolyte accommodated in the can 1, a circular lid 3 for closing the upper surface of the opening of the battery can 1, and a flat upper insulating plate 5 disposed on the upper side of the electrode body 2 Including. The battery can 1 and the lid 3 are formed of a cold rolled steel plate (SPCC) or the like. The battery has an outer diameter of 17 mm and a height of 45 mm.

  In the center of the lid 3, as shown in FIG. 1, a terminal attachment hole 9 is formed in which the output terminal 7 is attached in a penetrating manner via an insulating gasket 6. When the outer peripheral edge of the lid 3 is seam welded to the inner peripheral surface of the opening of the battery can 1 by a laser, the battery can 1 and the lid 3 are electrically connected.

  The insulating gasket 6 is located on the inner side of the terminal mounting hole 9 and the upper and lower peripheral edges, and insulates the output terminal 7 from the lid 3. The insulating gasket 6 extends downward from the peripheral edge of the lower surface of the insulating part 6 a and extends downward from the output terminal 7. And a shielding portion 6b surrounding the lower portion. A pressing plate 10 is disposed below the insulating portion 6 a of the insulating gasket 6, and the shielding portion 6 b surrounds the lower portion of the output terminal 7 and the pressing plate 10.

  By caulking the output terminal 7 up and down, the output terminal 7 is fixedly attached to the periphery of the terminal mounting hole 9 of the lid 3 via the holding plate 10 and the insulating portion 6 a of the insulating gasket 6. In this state, the lower part of the output terminal 7 is exposed in the battery.

  The electrode body 2 has a belt-like positive electrode 11 and a belt-like negative electrode 12 as electrodes, and is formed by spirally winding a belt-like separator 13 between the positive electrode 11 and the negative electrode 12. Is done. The separator 13 is made of a microporous thin film made of polypropylene resin.

  The positive electrode 11 is formed by arranging a positive electrode agent on both the front and back surfaces of a positive electrode current collector 11a made of a mesh stainless steel foil. The positive electrode agent contains manganese dioxide as a positive electrode active material, a binder, carbon black, and the like. The negative electrode 12 is formed by arranging lithium metal or a lithium alloy as a negative electrode active material on both sides of a negative electrode current collector 12a made of copper foil. A thin plate-like positive electrode current collecting lead 15 is led out from the positive electrode 11, and a thin plate-like negative electrode current collecting lead 16 is led out from the negative electrode 12.

  A cleaving vent 17 is formed near the outer periphery of the lid 3, and the cleaving vent 17 is cleaved to release the battery internal pressure when the battery internal pressure rises abnormally. A liquid injection hole 19 for injecting an electrolyte into the battery can 1 is formed in the lid 3, and a plug 20 is disposed in the liquid injection hole 19 after the injection of the electrolyte and is seam welded with a laser. .

  As shown in FIG. 1, a positive electrode current collecting lead 15 is welded and connected to the lower end surface 7a of the output terminal 7 after the caulking process. The negative electrode current collector lead 16 is welded and connected to the inner peripheral upper end portion of the battery can 1. As a result, the output terminal 7 has a positive potential, and the battery can 1 and the lid 3 have a negative potential. The negative electrode current collector lead 16 may be welded to the inner surface of the lid 3. The electrode body 2 is formed such that its outer peripheral surface is wound around the separator 13.

  As shown in FIG. 1, the lower end of the shielding part 6b of the insulating gasket 6 comes into contact with the upper surface of the upper insulating plate 5, and this restricts the electrode body 2 from moving upward. That is, even if the battery is accidentally dropped with the output terminal 7 facing down, the electrode body 2 is received by the insulating gasket 6 via the upper insulating plate 5, and the positive electrode 11 of the electrode body 2 is attached to the lid 3 or the like. It is possible to prevent the negative electrode 12 of the electrode body 2 from coming into contact with the output terminal 7 or the like. There may be a gap between the lower end of the shielding part 6 b and the upper surface of the upper insulating plate 5.

  The non-aqueous electrolyte is composed of an organic solvent containing propylene carbonate (PC), dimethyl ether (DME), or the like. The upper insulating plate 5 is made of polypropylene (PP) resin or the like and has a thickness dimension of 0.1 mm. The insulating gasket 6 is made of polypropylene (PP) resin, polyphenylene sulfide (PPS) resin, or the like. The holding plate 10 is formed in a ring shape from stainless steel. In the battery according to the present invention, the battery can 1 may have a bottomed rectangular tube shape or the like. As shown in FIG. 2, a lower insulating plate 21 made of polypropylene (PP) resin or the like is disposed on the bottom of the battery can 1.

  When assembling the battery, the output terminal 7, the insulating gasket 6 and the holding plate 10 are attached to the lid 3 as described above, and the lower insulating plate 21, the electrode body 2 and the upper insulating plate 5 are placed in the battery can 1. After the housing, the positive current collecting lead 15 is welded to the lower end surface 7a of the output terminal 7 and the negative current collecting lead 16 is welded to the inner peripheral surface of the battery can 1 as described above.

  Next, the lid 3 is welded to the battery can 1 as described above, the electrolyte is injected from the liquid injection hole 19, and then the liquid injection hole 19 is closed by the plug 20 and welded to complete the battery.

  In this state, since the lower portion of the output terminal 7, the pressing plate 10, and the positive electrode current collecting lead 15 are surrounded by the shielding portion 6b of the insulating gasket 6, even if lithium metal is deposited on the inner surface of the lid 3, the lithium The contact of the metal with the output terminal 7, the holding plate 10, and the positive electrode current collecting lead 15 is reduced.

Example 2 FIG. 3 shows Example 2 of a sealed battery targeted by the present invention. In Example 2, the lower part of the output terminal 7 exposed in the shielding part 6 b of the insulating gasket 6, the pressing plate 10, and the upper part of the positive electrode current collecting lead 15 are covered with an insulating paint (insulating material) 23. As a material of the insulating paint 23, an insulating material having resistance to the electrolytic solution such as UV curable resin, rubber-based resin, vinylidene fluoride (PVDF) resin, water glass (sodium silicate solution), or the like. Is set.

  As a covering method with the insulating paint 23, for example, after attaching the output terminal 7, the insulating gasket 6 and the pressing plate 10 to the lid 3 as described above, the shielding portion 6b of the insulating gasket 6 is turned upside down. In this manner, the insulating coating material 23 is poured into the shielding portion 6b from the opening of the shielding portion 6b and solidified into a semi-solid or solid state. Since the other points are the same as those of the first embodiment, description thereof is omitted.

FIG. 2 is an enlarged longitudinal front view of the main part of the sealed battery according to Example 1 of the invention Overall front view of sealed battery Enlarged longitudinal front view of essential parts of a sealed battery according to Example 2 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery can 2 Electrode body 3 Cover 5 Upper insulating board 6 Insulating gasket 6a Insulating part 6b Shielding part 7 Output terminal 9 Terminal mounting hole 10 Holding plate 11 Positive electrode 12 Negative electrode 13 Separator 23 Insulating paint

Claims (5)

A bottomed cylindrical battery can having an open top surface, an electrode body having a positive electrode and a negative electrode and housed in the battery can, a lid for closing the open top surface of the battery can, and the positive electrode and the negative electrode An output terminal to which either one is connected; and a terminal mounting hole formed in the lid and attached to the output terminal in a penetrating manner through an insulating gasket, and a lower portion of the output terminal is exposed in the battery In a sealed battery
The sealed gasket includes an insulating portion that insulates the output terminal from the lid, and a shielding portion that extends downward from the insulating portion and surrounds a lower portion of the output terminal. The electrode body is formed by winding with a separator interposed between the strip-shaped positive electrode and the strip-shaped negative electrode,
The sealed battery according to claim 1, wherein lithium metal or a lithium alloy is used as the negative electrode active material of the negative electrode. A flat insulating plate is disposed on the upper side of the electrode body,
3. The sealed battery according to claim 1, wherein a lower end of the shielding portion of the insulating gasket contacts the insulating plate to restrict upward movement of the electrode body. A pressing plate is disposed below the insulating portion of the insulating gasket;
The output terminal is fixed to the periphery of the terminal mounting hole through the insulating portion of the pressing plate and the insulating gasket,
The sealed battery according to claim 1, 2 or 3, wherein the shielding portion of the insulating gasket surrounds a lower portion of the output terminal and the pressing plate.   The sealed battery according to claim 1, 2, 3, or 4, wherein a lower portion of the output terminal is covered with an insulating material in the shielding portion of the insulating gasket.

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