JP2007188711A - Sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed battery of high reliability in which occurrence of a malfunction caused by transference of a battery element at falling and an shock is suppressed. <P>SOLUTION: In the sealed battery 1, the upper part insulating plate 5 in which a hole 7, a thick-walled side wall 8, and a rib 9 are installed between the battery element 3 and a cap body 4 is arranged. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a battery structure, and more particularly, to a sealed battery excellent in safety during dropping and impact.

  Various types of batteries are used as power sources for small electronic devices, and small and large-capacity sealed batteries are used as power sources for mobile phones and laptop computers. Recently, lithium-ion secondary batteries with particularly high energy density are used. A sealed battery using a non-aqueous electrolyte is used. In addition, along with the thinning of electronic devices, the use of rectangular batteries suitable for thin devices has become more space efficient, and complete sealing is essential because non-aqueous electrolyte is contained. .

  4A and 4B are diagrams for explaining an example of a conventional sealed battery, FIG. 4A is a plan view, FIG. 4B is a cross-sectional view taken along the line AA, and FIG. It is a figure explaining the state of the upper insulating board 5 between the inner cover body 4 and the battery element 3, FIG.4 (c) is a top view of the upper insulating board 5, FIG.4 (d) is upper insulation. It is a front view of a board. In the battery shown in FIG. 4, a battery can 2 made of aluminum or an alloy thereof is laminated with a positive electrode and a negative electrode through a separator, wound, molded battery element 3 is accommodated, and lid 4 is fitted to battery can 2. After that, laser welding. In the case of this battery, an upper insulating plate 5 and a lower insulating plate made of polyethylene resin or polypropylene resin are disposed above and below the battery element 3.

  In Patent Document 1, it is proposed to arrange an insulating plate having elasticity in order to suppress internal short circuit between the battery element, the lid, and the battery can due to dropping or impact. In Patent Document 2, the impact resistance is improved. Therefore, it has been proposed to arrange an insulating plate having a T-shaped cross section between the battery element and the battery can.

JP 200431263 A JP 2004-6363 A

  However, when the number of drop tests for confirming the safety of the battery is repeated, particularly when the drop test is repeatedly performed with the lid disposed below, an impact is applied to the upper portion of the can. 5A and 5B are diagrams for explaining a state of a conventional sealed battery after a drop test. FIG. 5A is a plan view, and FIG. 5B is a cross-sectional view taken along line AA in FIG. is there. As shown in FIG. 5, the battery element 3 moves to the lid 4 side due to a drop impact, and pushes up the upper insulating plate 5. Therefore, the upper insulating plate 5 is deformed. In order to connect the tab drawn from the battery element 3 to the lid 4, the slit portion provided in the upper insulating plate 5 is also brought into close contact with the deformation, and the space surrounded by the upper insulating plate 5 is sealed with a non-aqueous electrolyte. It may become a state. Further, when the upper insulating plate 5 is deformed to the lid body 4 side by a drop impact, the pressure in the sealed space is increased and the pressure is applied to the safety valve mechanism 6 and the safety valve mechanism 6 may be opened.

  In order to suppress the release of the safety valve mechanism in such a drop test, there is a measure to increase the operating pressure of the safety valve mechanism, but when the operating pressure is increased, the internal rise of the battery due to overcharge or short-circuit phenomenon, which is the initial purpose, is increased. Since the effect to prevent is remarkably impaired, it is not realistic.

  The present invention provides a highly reliable sealed battery that prevents a safety valve mechanism from being opened due to dropping and impact.

  The sealed battery of the present invention accommodates a battery element in which a positive electrode and a negative electrode are stacked and wound through an opening of a battery can through a separator, and the opening is sealed with a lid incorporating a safety valve mechanism. In the sealed battery according to the present invention, an upper insulating plate provided with a hole in at least a portion of the lid facing the safety valve mechanism is disposed between the battery element and the lid.

  In addition, the sealed battery of the present invention accommodates a battery element in which a positive electrode and a negative electrode are stacked and wound from an opening of a battery can through a separator, and the opening is sealed with a lid incorporating a safety valve mechanism. In this sealed battery, an upper insulating plate having a side wall at the peripheral portion and a rib at the center is disposed between the battery element and the lid. It is preferable that the bottom portion of the upper insulating plate has a thick portion, the side wall thickness of the upper insulating plate is 0.4 mm to 0.8 mm, and the rib width is 0.6 mm to 1 mm.

  Furthermore, in the sealed battery of the present invention, the upper insulating plate may be provided with a hole in a portion facing the safety valve mechanism of the lid, may have a side wall at a peripheral portion, and a rib at a central portion.

  According to the present invention, by using an upper insulating plate having a hole in a portion facing the safety valve mechanism of the lid or an upper insulating plate having a side wall at the peripheral portion and a rib at the center portion, When the safety valve mechanism is opened at the time of impact, safety can be secured by improving durability, and a highly reliable sealed battery can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view and a longitudinal sectional view for explaining a first embodiment of a sealed battery of the present invention. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1C is a plan view of the upper insulating plate in FIG. 1B, and FIG. 1D is a front view of the upper insulating plate. In the sealed battery 1 of the present invention, a positive electrode and a negative electrode are laminated in a rectangular battery can 2 via a separator and wound flat, and then pressed to be flattened so as to match the shape of the battery can. The battery element 3 is accommodated and sealed with a lid 4 incorporating a safety valve mechanism 6. An upper insulating plate 5 is disposed between the battery element 3 and the lid 4 to prevent a short circuit. The upper insulating plate 5 is provided with a convex side wall on the side of the lid 4 at the upper peripheral edge of the upper insulating plate 5 in order to avoid contact between the lid 4 and the terminal portion at the substantially central portion of the lid and the battery element 3. The hole 7 was provided in the part facing the safety valve mechanism 6 of the lid 4 on the battery element 3 side.

  Here, the hole 7 of the upper insulating plate 5 is a through-hole communicating with the battery element 3 and the lid 4 side as shown in the front view of the upper insulating plate in FIG. By providing the hole 7 in the upper insulating plate 5, the battery element 3 moves to the lid 4 side when receiving an impact such as a drop test, and the upper insulating plate 5 is pressed and the upper insulating plate 5 is deformed. Even in this case, the pressure in the space surrounded by the lid body 4 and the upper insulating plate 5 is released. In the sealed battery of the present invention, the space surrounded by the lid and the upper insulating plate does not become sealed even when the battery element moves to the lid side when dropped or impacted.

  FIG. 2 is an explanatory diagram of a second embodiment of the sealed battery of the present invention. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along line AA in FIG. 2A. 2C is a plan view of the upper insulating plate in FIG. 2B, and FIG. 2D is a front view of the upper insulating plate. In order to suppress deformation due to external force of the upper insulating plate 5 and increase strength, a convex thick side wall 8 is provided on the lid 4 side of the upper peripheral edge of the upper insulating plate 5 and a bottom 5a on the battery element 3 side is provided. It has a thick shape. A rib 9 is provided on the inner side.

  Here, the thick side walls 8 and ribs 9 of the upper insulating plate 5 have a structure that increases the strength against the force from above and below the upper insulating plate, as shown in the plan view of the upper insulating plate in FIG. It has become. By increasing the strength of the upper insulating plate 5, the battery element 3 moves to the lid 4 side when receiving an impact such as a drop test, and deformation caused by pressing the upper insulating plate 5 is reduced.

  FIG. 3 is an explanatory diagram of the third embodiment of the sealed battery of the present invention. 3A is a plan view, and FIG. 3B is a cross-sectional view taken along line AA in FIG. 3C is a plan view of the upper insulating plate in FIG. 3B, and FIG. 3D is a front view of the upper insulating plate. A hole 7 is provided in a portion of the lid of the upper insulating plate 5 facing the safety valve mechanism 6, a convex thick side wall 8 is provided on the lid 4 side of the upper peripheral edge, and a bottom portion 5 a on the battery element 3 side. The shape is thickened. A rib 9 is provided on the inner side. That is, the first embodiment and the second embodiment are combined.

  As shown in FIG. 1, after placing a lower insulating plate in a battery can made of an aluminum alloy having a length of 49.1 mm, a width of 33.8 mm, a thickness of 4.5 mm, and a plate thickness of 0.2 mm, the positive electrode and the negative electrode are finely connected. A battery element having a length of 45.5 mm, a width of 32.6 mm, and a thickness of 3.7 mm produced by laminating through a porous polypropylene membrane separator and winding in a spiral shape is accommodated, and a lid body through an upper insulating plate After welding to the can, laser welding. After injecting the electrolyte, the inlet was sealed to produce a lithium ion battery. The upper insulating plate has a plate-like portion having a thickness of 0.3 mm, and has a width of 0.3 mm and a height of 3.7 mm in length and 32.2 mm in width except for the portion connecting the negative electrode tab to the can. Protruding side walls with a thickness of 1.3 mm are provided, and a hole 7 having a length of 3.7 mm, a width of 2 mm, and a height of 0.8 mm is provided in a portion of the long bottom surface facing the safety valve mechanism. Used as Example 1.

  As shown in FIG. 2, the upper insulating plate has a plate-like portion with a thickness of 0.4 mm, and has a width of 3.7 mm and a width of 32.2 mm, except for the portion connecting the negative electrode tab to the can. Example 1 except that a convex thick side wall 8 having a height of 0.5 mm and a height of 1.2 mm was provided and a rib having a width of 0.6 mm and a height of 0.4 mm was provided on the inner side. A lithium ion battery was produced and used as Example 2.

  As shown in FIG. 3, the upper insulating plate has a plate-like portion having a thickness of 0.4 mm, and a convex shape having a width of 0.5 mm and a height of 1.2 mm on the upper edge of the peripheral portion having a length of 3.7 mm and a width of 32.2 mm. Except that a thick side wall 8 is provided, ribs with a width of 0.6 mm and a height of 0.4 mm are provided on the inside, and a hole 7 with a diameter of φ1.6 mm is provided at three locations near the center and both ends. A lithium ion battery was produced in the same manner as in Example 1, and Example 3 was obtained.

(Comparative example)
As shown in FIG. 4, the upper insulating plate has a plate-like portion having a thickness of 0.3 mm, and a convex shape having a width of 0.3 mm and a height of 1.3 mm on the upper peripheral edge portion of 3.7 mm in length and 32.2 mm in width. A lithium ion battery was produced as a comparative example in the same manner as in Example 1 except that the one provided with the side wall was used.

  A battery pack was obtained in which the battery produced as described above was packaged with a case made of molded resin together with a protective circuit. The obtained three battery packs are mounted on an MC (monomer cast) nylon jig of 80 g weight assuming a mobile phone, and the direction of the battery lid is controlled to the lower part from a height of 1 m onto the plywood. A drop test was conducted. Table 1 summarizes the results of the number of drops when the safety valve mechanism was opened by the drop impact of the example and the comparative example.

  From the results shown in Table 1, the sealed battery according to the present invention was provided with a hole in the upper insulating plate between the battery element and the lid and increased the thickness of the side wall and the bottom surface. In some cases, the safety valve mechanism was not opened, and it was confirmed that it could be used as a sealed battery requiring high durability. When the thickness of the side wall is thinner than 0.4 mm, it is weak against pressing from above and below, and the upper limit is set to 0.8 mm due to dimensional restrictions. Similarly, when the width of the rib is thinner than 0.6 mm, it is weak against pressing from above and below, and the upper limit is set to 1.0 mm due to dimensional restrictions.

The figure explaining 1st Embodiment of the sealed battery of this invention. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1C is a plan view of the upper insulating plate in FIG. 1B, and FIG. 1D is a front view of the upper insulating plate. The figure explaining 2nd Embodiment of the sealed battery of this invention. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along line AA in FIG. 2C is a plan view of the upper insulating plate in FIG. 2B, and FIG. 2D is a front view of the upper insulating plate. The figure explaining 3rd Embodiment of the sealed battery of this invention. 3A is a plan view, and FIG. 3B is a cross-sectional view taken along line AA in FIG. 3C is a plan view of the upper insulating plate in FIG. 3B, and FIG. 3D is a front view of the upper insulating plate. The figure explaining the conventional sealed battery. 4A is a plan view, FIG. 4B is a sectional view taken along line AA in FIG. 4A, FIG. 4C is a plan view of the upper insulating plate in FIG. 4B, and FIG. (D) is a front view of an upper insulating plate. The figure explaining the state after the drop test of the conventional sealed battery. FIG. 5A is a plan view, and FIG. 5B is a cross-sectional view taken along the line AA in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealed battery 2 Battery can 3 Battery element 4 Lid 5 Upper insulating plate 5a (Upper insulating plate) Bottom 6 Safety valve mechanism 7 Hole 8 Side wall 9 Rib

Claims (5)

  A sealed battery comprising a battery element in which a positive electrode and a negative electrode are stacked and wound through a separator through an opening of a battery can, and the opening is sealed with a lid body incorporating a safety valve mechanism. A sealed battery comprising an upper insulating plate provided with a hole in at least a portion of the lid facing the safety valve mechanism between the element and the lid.   A sealed battery comprising a battery element in which a positive electrode and a negative electrode are stacked and wound through a separator through an opening of a battery can, and the opening is sealed with a lid body incorporating a safety valve mechanism. A sealed battery comprising an upper insulating plate having a side wall at a peripheral portion and a rib at a central portion between an element and the lid.   3. The sealed battery according to claim 2, wherein the upper insulating plate has a thick portion at the bottom.   3. The sealed battery according to claim 2, wherein a thickness of the side wall of the upper insulating plate is 0.4 mm to 0.8 mm, and a width of the rib is 0.6 mm to 1.0 mm.   2. The sealed battery according to claim 1, wherein the upper insulating plate has a side wall at a peripheral portion and a rib at a central portion.

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