JPH08185835A - Square sealed battery - Google Patents

Abstract

PURPOSE: To manufacture a square sealed battery with high sealing capability and high strength by filling a power generating element in a square metal case with bottom, fitting a cover into an opening of the metal case with no level difference, then sealing by means of electrical resistance welding. CONSTITUTION: A sheet-like battery (c) for a lithium ion secondary battery functioning as a power generating element is filled in a square stainless steel case (b) having no level difference (level difference is 49/1000mm or less) in an opening. A cover (a) with step is fitted to the opening, and the case (b) and the cover (a) are welded by electrical resistance welding to produce a square battery. The square sealed battery with very high strength and high sealing capability can be obtained.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectangular sealed type in which electric resistance welding is improved, an opening and a lid of a metal case are improved, and laser welding is changed to electric resistance welding. It concerns batteries. [0003] 2. Description of the Related Art [0004] With the development of mobile phones and notebook type personal computers, the size, weight, and size of the devices are becoming smaller. A high-performance battery having a long cycle life is used as a power source of these devices. These batteries can withstand the internal gas pressure during charging even when the battery is charged many times, so to prevent deformation of the case due to repeated charging, or to prevent the case from melting and opening holes when over-discharging. Is used. In addition, both the iron case and the lid, which are easier to weld than the stainless steel case, were laser welded to complete the rectangular sealed battery by welding the case and lid. The welding of the battery opening of nickel-cadmium secondary battery, nickel-hydrogen secondary battery, and lithium-ion secondary battery is sealed by laser welding, but the joint is a line and it is extremely narrow and spot welding is continuous. At the same time, thermal deformation of the case started, and the corner portion of the square shape swelled as welding proceeded, so that a sufficient degree of sealing could not be maintained and the strength was insufficient. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is to weld a rimmed metal case and a step-molded lid by surface by an electric resistance welding method. The purpose of the invention is to manufacture a prismatic battery having a high degree of sealing and a high strength. [Means for Solving the Problems] As described above, the problem of the laser welding is that the spot welding is continuous, so that the thermal deformation of the case starts when the welding starts. The deformation of the case increases as welding progresses, and the shape of the case and the shape of the lid do not match, especially at the corners of the square shape. For this reason, even if welding is performed, sufficient airtightness cannot be maintained and the strength is reduced. When the electric resistance welding method is used, all the joints between the case opening and the lid can be welded on the surface instantly within 1/30 seconds or less, so that deformation of the case and the lid during welding can be avoided. However, since a metal case having a cutting step of 5 / 100-9 / 100 mm has been conventionally used, the contact between the metal case opening and the lid is not sufficient, and welding is not possible where the lid and the metal case opening are separated. It was If the lid and the metal case opening are brought into close contact with each other, the entire case opening can be sealed by electric resistance welding. Since the lid is in close contact with the entire surface of the metal case opening, there is no step difference in cutting the metal case opening. Further, by increasing the contact area between the lid and the metal case and increasing the area to be welded by electric resistance welding, the airtightness of the rectangular battery can be improved. According to the present invention, the electric resistance welding method and the cut-off of the rectangular metal case which enables it and the molding diaphragm of the lid are integrated, and the sealing property of the welded portion of the opening of the metal case is integrated. And the strength can be dramatically increased compared to the laser welding method. Further, the present invention is not only applicable to a wide range of metal materials, but also between metal cases and lids in which stainless steel foil is pressed, paper or resin cases and lids in which stainless steel foil is lined. It can be applied. Further, when the present welding method is used, it is possible to weld the joint portion only once and the welding time is as short as 1/30 seconds or less, so that the workability of several tens of times can be secured compared to the laser welding. EXAMPLE 1 As shown in FIG. 1, a sheet-like electrode for a lithium ion secondary battery, which is a power generating element (a lead terminal is ultrasonically welded to a positive electrode and a negative electrode, and then a separator is placed between a positive electrode and a negative electrode. There is no step in the opening (step 49/10
Place it in a square stainless steel case (within 00 mm) and put a stepped lid on it. A rectangular battery was manufactured by welding the rectangular stainless case and the lid on the surface by the electric resistance welding method.
100 pieces of the above batteries were made by changing the wall thickness of the lid, and the airtightness was evaluated by a helium leak test (10 ⁻⁹ Torr). The results are shown in Table 1. Regardless of the shape of the two types of lids shown in FIG. 1 and the wall thickness of the lids, no leak was observed in all the batteries, and a square sealed battery can be manufactured by this method. Also,
The thickness of the level difference of the stepped molded lidded cases and tolerances (0.0
No welding burrs were found inside the cans when they matched within 5 m / m). [Embodiment 2] A power generating element is provided in an opening on 5 / 100-9 / 10.
It is filled in a square stainless case having a step of 0 mm, and a flat lid shown in FIG. A rectangular battery was manufactured by welding the rectangular stainless case and the lid on the surface by the electric resistance welding method. About 20% of the above 100 batteries are not sealed. [Third Embodiment] The power generation element has no step (step 49/100).
(Within 0 mm) Fit in a square stainless steel case and place a flat lid on it. A rectangular battery was manufactured by welding the rectangular stainless case and the lid on the surface by the electric resistance welding method. There was no problem with the airtightness of the battery. [Embodiment 4] As shown in FIG. 3, a power generation element is fitted into a rectangular stainless steel case having no step at the opening (step 49/1000 mm or less), and the case opening and the stepped lid are attached. Secure with adhesive. A square sealed battery was manufactured by an electric resistance welding method. The adhesive, which does not harm the power generation element, maintained airtightness and did not lower the welding strength. Example 5 A rectangular aluminum case was cut off by a single pressing step. An aluminum lid manufactured by using the forming and drawing method was placed on this and welded by electric resistance welding. Regarding the above 100 batteries, the result of the leak test was good, and no battery was found to have a leak. [Embodiment 6] Metal rectangular battery case and 20 inside the lid
A -100 micron stainless foil was lined by pressing. A power generating element was placed in this case, and a rectangular sealed battery was manufactured by stacking a lid made of stainless steel foil of 5 to 50 microns on a stepped stainless lid or a lid made of resin or paper and electric resistance welding. . A suitable thickness for the stainless steel foil is 20-100 microns. It was confirmed by a leak test that this battery was sealed. Example 7 A resin rectangular battery case and a lid 20
A -100 micron stainless foil was lined. Put the power generation element in this case and put it in a lid made of resin or paper for 5-50
A rectangular sealed battery was manufactured by stacking lids covered with micron stainless steel foil and performing electric resistance welding. Paper may be used for the outer case.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a stainless steel square sealed battery used in Example 1 and a cross-sectional view of a lid. FIG. 2 is a cross-sectional view of a stainless steel case and lid used in Example 2. [Fig. 3] Cross-sectional view of the stainless steel case and lid used in Example 4 [Explanation of reference signs] (a) Two types of stainless steel lids with stepped cutting No flat stainless steel lid E 5 / 100-9 / 100mm step difference Conventional stainless steel cutting with step difference Adhesive

Claims (1)

[Claims] 1. A rectangular sealed battery manufactured by inserting an adhesive agent alone into the opening of a rectangular metal case with a bottom filled with a power generating element, or inserting a sealing lid plate without an inclusion and sealing by electric resistance welding. In order to ensure this electric resistance welding, a rectangular sealed battery characterized in that the opening of the metal case is cut off in one pressing step, and there is no step at the cut end. With this method, it is possible to make the welding tightness of the joint much more reliable than the conventional laser welding and to make the welding strength higher than that of the base metal. 2. The rectangular sealed battery according to claim 1, wherein an electric resistance welding method is used to prevent welding burrs from being generated inside the case at the joint by using a lid formed in a stepped shape. The material of the metal case and the sealing cover plate can be any metal material such as stainless steel, nickel-plated steel plate, and aluminum, and the material of the case and the sealing cover plate may be different. 3. In a sealed battery in which the internal pressure generated when the power generation element is charged or overcharged is extremely small, a conductive metal foil (20-100 microns) such as stainless steel foil is pressed into a square battery case, and a step is provided. A rectangular sealed battery characterized in that a stainless steel lid or a stepped paper or resin lid covered with a metal foil of 20-100 microns is resistance-welded. A rectangular case made of paper or various resin made of metal foil (5-50 microns) and 5-
A square sealed battery characterized by being electrically resistance welded to a stepped paper or resin lid covered with a 50-micron metal foil. [0002]