WO1998029911A1

WO1998029911A1 - Nonaqueous electrolyte battery and manufacture of sealing plate thereof

Info

Publication number: WO1998029911A1
Application number: PCT/JP1997/004679
Authority: WO
Inventors: Hiroshi Yoshizawa; Kazunori Haraguchi; Takuya Nakajima; Takashi Takeuchi; Yoshitaka Matsumasa; Kikuo Senoo; Takafumi Fujii; Mamoru Iida; Kenji Mizuno
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 1996-12-25
Filing date: 1997-12-18
Publication date: 1998-07-09

Abstract

A structure of an explosion-proof safety valve of a compact nonaqueous electrolyte battery, such as, a lithium ion secondary battery, which is thin and rectangular or has an elliptic cross section with a small sealing plate area, and manufacture of a sealing plate. By reliably actuating the explosion-proof valve with a simple structure and without sacrificing the capacity, the safety of the battery is to be ensured. An aperture upper edge portion of a metallic bottomed cell container and a peripheral edge portion of a metallic sealing plate are hermetically sealed by laser welding. A through-hole is provided at a center portion of the sealing plate, and a rivet which also functions as a terminal is clamped, hermetically sealed and fixed through a gasket. An exhaust hole is provided between the terminal and the peripheral edge portion of the sealing plate, and this exhaust hole is closed by a metal foil, thus providing the explosion-proof safety valve. With such a simple structure, the valve operates accurately to prevent fault. Also, this sealing plate is continuously manufactured in a hoop-like shape.

Description

Description Non-aqueous electrolyte battery and method for producing sealing plate

The present invention relates to a battery explosion-proof mechanism using a non-aqueous electrolyte such as an organic electrolyte, and a method for manufacturing a sealing plate provided with an explosion-proof safety valve therefor. Background art

In recent years, with the advancement of electronics technology, it has become possible to reduce the size and weight and to reduce power consumption, as well as to enhance the functions of electronic devices. As a result, various portable portable devices have been developed and put into practical use, and their market scale is rapidly expanding. Typical examples are camcorders, notebook computers, and mobile phones.

There is a continuing demand for smaller and lighter devices and longer operating times. In response to such demands, lithium secondary batteries typified by long-life, high-energy-density lithium-ion secondary batteries have been actively developed and widely adopted as built-in power supplies for driving these devices. Under these circumstances, thin rectangular batteries, which are particularly suitable for thinning equipment and have a large space effect, are gaining importance.

Lithium ion secondary batteries are composed of a composite oxide of lithium and a transition metal element as a positive electrode active material, graphite-based carbon as a negative electrode active material, an organic electrolyte solution that is an organic solvent solution of a lithium salt as an electrolyte, and a lithium ion conductor. This is a battery system that uses a non-aqueous electrolyte such as a solid electrolyte. In this battery, lithium ions are released from the lithium-containing composite oxide of the positive electrode upon charging and eluted into the electrolyte, and at the same time, the same electrochemical equivalent of lithium ions is absorbed from the electrolyte into the carbon of the negative electrode. . At the time of discharging, lithium ions are occluded in the positive electrode to become a lithium-containing composite oxide, and lithium ions are repeatedly released from the negative electrode, as opposed to during charging. Because of this behavior, lithium ion rechargeable batteries were identified as rocking chair batteries. Lee.

Since the potential of the carbon negative electrode is close to the electrode potential of metallic lithium, the composite of lithium and at least one transition metal element selected from the group of cobalt, nickel and manganese exhibiting a high electrode potential is used for the positive electrode. Oxides are commonly used as active materials.

These lithium-ion secondary batteries have the advantage of being extremely high in the energy density per unit volume as well as the energy density per unit weight, among the battery systems currently in practical use. However, in many cases, an organic electrolyte is used, so in the case of an external short circuit or overdischarge involving overcharge or reverse charge, the flowing current raises the battery temperature and evaporates or decomposes the solvent in the organic electrolyte. As a result, the internal pressure of the battery suddenly and abnormally increased, and not only did the battery container rupture and leaked, but also there was a risk of a fire accident if current continued to flow.

Therefore, in order to prevent a sudden and abnormal rise in the internal pressure of the battery and a fire accident as described above, an overcharge and overdischarge prevention circuit is usually built in a battery pack consisting of a plurality of cells, and the internal pressure of the battery is reduced. When it rose, an explosion-proof safety valve was activated to release the high-pressure gas in the battery to the atmosphere, and a PTC element was provided in each cell to prevent excessive current from flowing. However, even with these measures, it was difficult to ensure battery safety perfectly. Therefore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-111121, a lead plate of an electrode plate is attached in advance to an explosion-proof valve that deforms as the internal pressure increases, and the internal pressure reaches a predetermined value. At times, a mechanism has been proposed in which the explosion-proof valve is deformed and the attached lead plate breaks or peels off from the explosion-proof valve, thereby interrupting the current. This mechanism cuts off the current by utilizing the rise in the internal pressure of the cell caused by external short-circuiting, overdischarging accompanied by overcharging and reverse charging, etc. ing. In particular, it can be said to be an effective mechanism for cylindrical or square batteries with relatively large dimensions. However, small batteries with a small sealing plate area, such as thin rectangular batteries and thin cylindrical batteries, have varying operating pressures and cannot be applied in terms of both reliability and productivity. There were drawbacks.

The present invention relates to a small battery having a small sealing plate area, particularly a thin battery having a rectangular or long cross section. Explosion-proof, highly productive and highly reliable circular lithium-ion rechargeable batteries with a relatively simple sealing plate that operates accurately without sacrificing discharge capacity It is intended to provide a non-aqueous electrolyte battery provided with a safety valve for use. Disclosure of the invention

According to the present invention, the same metal as the cell container is provided at the upper edge of the opening of the metal bottomed cell container containing a battery element composed of a non-aqueous electrolyte and an electrode group composed of a positive electrode and a negative electrode through a separator. The sealing between the cell container and the sealing plate is integrated by laser welding with the sealing plate made of glass fitted, and the through hole provided in the center of the sealing plate is electrolyte-resistant and electric. A metal rivet also serving as a terminal is inserted and fixed via an insulating synthetic resin gasket, and at least one exhaust hole is provided between the terminal and the peripheral edge of the sealing plate. This is a non-aqueous electrolyte battery equipped with an explosion-proof safety valve that closes the exhaust hole by press-fitting and integrating metal foil on at least the periphery of the exhaust hole on the inner surface of the lid plate that is the base material.

More specifically, when aluminum is used for the metal foil that closes the exhaust hole forming the safety valve for explosion-proof, the aluminum foil is fixed in a state that it protrudes outward toward the outside of the cell, or When nickel, stainless steel or nickel-plated steel is used as the metal foil, the reliability of the operation of the safety valve for explosion-proof is improved by forming a thin pattern in advance on the metal foil that blocks the exhaust hole. Thus, in small non-aqueous electrolyte batteries, it is possible to completely prevent rupture accidents. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a longitudinal sectional view of a prismatic lithium ion secondary battery according to one embodiment of the present invention.

FIG. 2 shows an external plan view of a prismatic lithium ion secondary battery according to the present invention. FIG. 3 shows an example of an enlarged sectional view of an explosion-proof safety valve section of an aluminum lid plate and a sealing plate made of metal foil according to the present invention.

FIG. 4 is a flow chart for continuously manufacturing a sealing plate according to the present invention. It is an example.

FIG. 5 is a perspective view of a band-shaped cladding plate for a sealing plate obtained by pressure bonding and integrating a cover plate and a metal foil, which are base materials of the sealing plate according to the present invention.

FIG. 6 is an external perspective view of a continuous strip hoop material for supplying a sealing plate according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings and tables. <Example 1>

FIG. 1 is a longitudinal sectional view of a thin to square lithium ion secondary battery according to one embodiment of the present invention. In FIG. 1, an aluminum sealing plate 2 is fitted to the upper edge of the opening of a bottomed rectangular cell container 1 made of aluminum, and the fitting portions 3 are integrated by laser-welding to be liquid-tight. And it is hermetically sealed. The sealing plate 2 is molded so that its center is concavely indented inward, and the through holes provided are coated with a sealant made of a mixture of blown asphalt and mineral oil. A gasket 4 made of an electrically insulating synthetic resin is attached to the body. A nickel or nickel-plated steel rivet 5 also serving as a negative electrode terminal is inserted into the gasket 4, and the tip of the rivet 5 is caulked while the nickel or nickel-plated steel washer 6 is fitted to the lower part of the rivet 5. Secure and seal liquid-tight and air-tight. The gasket 4 was molded integrally with the sealing plate 2 by injection molding. An elliptical exhaust hole 7 is provided between the negative electrode terminal 5 and the outer edge of the long side of the sealing plate 2, and an aluminum foil 8 is crimped and integrated on the inner surface of the sealing plate 2. The exhaust port 7 is closed by the aluminum foil 8 to form an explosion-proof safety valve. One positive electrode and one negative electrode are wound through a separator 9 composed of a microporous polyethylene film, and the outermost circumference is wrapped with separator, forming an electrode group 10 having an oval cross section. . The aluminum positive electrode lead plate 11 of the electrode group 10 and the inner surface of the sealing plate 2 were connected and fixed by spot welding using a laser beam, and the nickel negative electrode lead plate 12 and the washer 6 were connected and fixed by resistance welding. ing. The sealing plate 2 is provided with a liquid injection hole 13 .After a predetermined amount of the organic electrolyte is injected, an aluminum lid 14 is fitted into the liquid injection hole 13, and then the sealing plate 2 and the lid 1 are formed. 4 A sealed battery can be completed if it is sealed liquid-tight and air-tight.

The positive electrode is composed of 100 parts by weight of a composite oxide of lithium and cobalt (LiCoO 2) as an active material, 3 parts by weight of acetylene black as a conductive agent, and polytetrafluoroethylene (solid) as a binder. (10 parts by weight) A base prepared by kneading a displaced solution and applied to both sides of a core aluminum foil, dried, cut into a predetermined size after pressurizing a roll. An aluminum positive electrode lead plate 11 is welded to the aluminum foil of the positive electrode core material.

For the negative electrode, paste prepared by kneading 100 parts by weight of graphite-based carbon powder of the negative electrode material and a dispersion solution of styrene butene rubber (solid content: 5 parts by weight) with a binder copper foil was used. It is coated on both sides, dried, roll-pressed, and cut to a specified size. A negative electrode lead plate 12 made of nickel is welded to the copper foil of the core material of the negative electrode. As the organic electrolyte, for example, lithium hexafluorophosphate (L i PF 6) 1. O mo 1 is mixed with ethylene carbonate (EC) and getyl carbonate (DEC) in a molar ratio of 1: 3. It is used at a concentration of 1.0 liter dissolved in a solvent. For the organic electrolyte, use a liquid injection device equipped with a three-way cock. First, the pressure inside the cell is reduced by a vacuum pump, and the cock is switched to inject the liquid. The organic electrolyte passes through the introduction groove 16 shown in FIG. 1 and firstly between the inner wall of the prismatic cell container 1 and the outer periphery of the electrode group 10 shown in the plan view of the prismatic battery in FIG. It accumulates in the space 17 formed. Therefore, there is an advantage that the organic electrolyte does not overflow and wet the injection hole 13 to make it difficult to perform welding in a later process. The organic electrolyte collected in the space 17 is sequentially absorbed and fixed in the electrode group 10. Although the electrode group 10 described here was wound so as to have an oval cross section, the present invention provides a plurality of positive electrodes and a plurality of positive electrodes via a separator like a general rectangular cell. The present invention can be applied to the case of an electrode group composed of a negative electrode.

FIG. 1 shows a state where the central portion of the sealing plate 2 is drawn and formed so as to be concavely recessed toward the inside of the cell. Regarding the presence or absence of such drawing process, the thermal effect of laser welding between the cell container and the sealing plate, the prototype square lithium-ion secondary battery of 50 cells each, The deformation rate of the gasket was visually observed, and the leakage rate after standing for 3 days at 85 in the charged state. Was examined. The gasket was made of polypropylene resin,

As is evident from Table 1, the effect of reducing the thermal effects during laser welding is apparent by forming the central part of the sealing plate by drawing so that it does not dent inward toward the inside of the cell. is there. In addition, it is expected that the pressure resistance of the sealing plate when the internal pressure of the cell rises can be improved by forming the concave drawing process in this manner.

FIG. 1 shows a state in which the aluminum foil 8 is crimped only to the portion that closes the exhaust hole 7, but the aluminum foil is applied not only to the exhaust hole 7 but also to the entire inner surface of the sealing plate 2. 8 may be crimped to form a clad plate. Example 2>

In the same manner as in the gasket used for the prototype cell in Example 1, a conventional lithium primary battery using metal lithium as the negative electrode active material, manganese dioxide, graphite fluoride, etc. as the positive electrode active material, and an organic electrolyte as the nonaqueous electrolyte In batteries, polypropylene resin is often used as the gasket material because of its excellent injection moldability and low cost. The compression ratio of the polypropylene gasket at the time of caulking is conventionally adjusted to be 50 to 70%.

In the present invention, since the gap between the cell container and the sealing plate is sealed by laser welding, it is necessary to consider the effect of heating the gasket. Therefore, in the present invention, it is desired that the gasket material be an electrolyte-resistant material that is relatively stable thermally. Also, in the case of a small battery such as a thin battery having a small sealing plate area such as a rectangular battery as in the present invention, the diameter of the rivet forming the negative electrode terminal is extremely small, so that the gasket when caulking the rivet is used. The compressibility of the material It is desirable to lower it to about 30%. First of all, referring to existing data, from among about 20 types of synthetic resins, three types of electrolyte-resistant polypropylene (PP), polyethylene terephthalate (PET) and polyphenylene sulfide (PPS) I picked the seed. Regarding the suitability of these three types of synthetic resins as gasket materials, the same prismatic lithium-ion secondary battery as in Example 1 shown in FIGS. 1 and 2 was prototyped, and 50 cells in the charged state were heated. Evaluation was made based on the liquid leakage rate after the impact test.

The thermal shock test was repeated for 100 cycles, with one cycle of standing at 150 for 1 h and then standing at 100 for 1 h. Table 2 shows the results.

Table 2

From Table 2, it can be seen that the gasket material used for the non-aqueous electrolyte battery of the present invention, which seals the gap between the cell container and the sealing plate by laser welding, with a rivet that also functions as a terminal at the center of the sealing plate, by caulking. It can be seen that the use of PPS resin, which has excellent heat resistance, improves liquid leakage resistance. The compression ratio of the gasket made of each resin was adjusted so as to have the same degree of sealing.

The shape of the exhaust hole with respect to the operating pressure of an explosion-proof safety valve in which a metal foil was pressure-bonded and integrated with the exhaust hole provided in the sealing plate according to the present invention was examined. Normally, a method of punching using a mold is industrially adopted as an exhaust hole opening process. Mold maintenance From the viewpoint of productivity and productivity, we excluded complex shapes such as triangles and stars as exhaust holes, and focused on four types of circular, elliptical, square, and rectangular shapes to examine variations in the operating pressure of explosion-proof safety valves. Each 100 sealing plates were examined. Table 3 shows the results.

Table 3

An aluminum lid plate (0.6 mm thick) and aluminum foil (0.3 mm thick), which are the base materials of the sealing plate, were pressed and clad using a roller. The operating pressure of the safety valve is greatly affected by the thickness of the aluminum foil and the shape of the exhaust hole. Table 3 shows that in the case of aluminum foil of the same thickness, the operating pressure of the safety valve varies greatly depending on the shape of the exhaust hole. In the case of the elliptical shape, the aluminum foil was selectively broken at the small part of the arc. Therefore, it is desirable to make the shape of the exhaust hole elliptical, if possible, from both aspects of the shape and dimensions of the sealing plate.

If the prismatic battery becomes thinner and the size of the sealing plate becomes smaller, the shape of the vent hole of the explosion-proof safety valve must be all elliptical, as confirmed in Example 3. It becomes difficult.

Therefore, when the shape of the exhaust hole is made circular with high precision and easy to process, it is desirable that the safety valve operates with a small variation.

As described above, the aluminum vent plate material, which is the base material of the sealing plate, and the aluminum foil are pressurized using a roller, and the cladding process is used to integrate them. A safety valve is formed. By increasing or decreasing the pressure applied by the nozzle, the aluminum foil closing the exhaust hole changes from a flat state to a state in which the aluminum foil bulges outward. However, when the roll is pressed excessively, the aluminum foil breaks and breaks, and the exhaust hole is not blocked, so that an explosion-proof safety valve cannot be formed.

Therefore, for an explosion-proof safety valve with a structure in which the exhaust hole of the sealing plate is closed with aluminum foil, as shown in Fig. 1, the aluminum foil is in a flat state, and is indicated by 8a in the enlarged sectional view of Fig. 3. As shown in the figure, the variation in operating pressure was measured for each of the two types of explosion-proof safety valves, in which the metal foil of aluminum or the like that closes the exhaust hole bulged convexly outward of the cell. Each sealing plate was examined. Table 4 shows the results.

Table 4

As is evident from Table 4, the variation in the operating pressure of the explosion-proof safety valve was smaller when the aluminum foil closing the exhaust hole bulged convexly outward of the cell. In this case, the shape of the exhaust hole in Example 3 is made elliptical. On the contrary, excellent results were obtained. The reason is not clear, but the gas pressure in the cell is evenly applied to the entire inner surface of the aluminum foil that bulges out in a convex shape, and the breakage in the linear crimping section between the aluminum foil and the inner circumference of the exhaust hole is even. It is presumed that it will be.

Example 5>

As non-aqueous electrolyte batteries, such as lithium-ion secondary batteries, are required to be highly reliable under severe environmental conditions as power supplies for portable equipment. When these batteries were left in a hot and humid state for a long period of time, some batteries were found to leak organic electrolyte from around the explosion-proof safety valve.

Therefore, a small amount of a solution in which organic tar, vaseline, asphalt, etc., which is chemically stable and has no hygroscopicity, is dissolved in an organic solvent is used. After application, the solvent was skipped and the effect of coating with an organic anticorrosive coating film was examined.

First, a sealing plate was prepared, in which an organic anticorrosive coating consisting of coal tar pitch and dicerin was previously formed on the outer surface of the aluminum foil closing the exhaust hole of the explosion-proof safety valve. Under the same conditions as in Example 1, 50 cells each of a prismatic lithium ion secondary battery were trial-produced, and were left in a charged state at 60 ° C. and a relative humidity of 90% for 3 power months. Table 5 shows the results of visually examining the leakage rate of the battery after standing.

5 Table Organic anticorrosives Leakage rate (% :) None 10 Coal tar pitch 2 Serine 2 As is evident from Table 5, by providing a coating made of an organic anticorrosive on the outer surface of the aluminum foil of the explosion-proof safety valve, the aluminum foil is less likely to corrode. It is considered that the liquid did not easily leak even after prolonged humid conditions.

In addition to coal tar pitch and petrolatum, non-hygroscopic, chemically stable and highly plastic materials, such as a mixture of bron bitumen and mineral oil, a sealant applied to the gasket surface, are also effective as organic anticorrosives It is.

Examples 1 to 5 are examples in which the cell container, the lid plate, and the sealing plate made of metal foil are all made of aluminum and have positive polarity. Further, the present invention has been described in detail with an example in which a terminal made of a rivet and a washer that are hermetically sealed via a gasket at the center of the sealing plate are usually made of nickel or nickel-plated steel and have a negative polarity. However, in the battery design, it is necessary to consider the necessity of reversing the polarity in the same cell structure shown in these embodiments. In other words, the cell container, the lid plate, and the sealing plate made of metal foil are all made of nickel, stainless steel, or nickel-plated steel, have negative polarity, and have a rivet that is sealed and fixed at the center of the sealing plate via a gasket. The terminal and the washer are made of aluminum and have a positive polarity. The present invention can be similarly implemented in batteries having the opposite polarity to those in Examples 1 to 5, and can achieve the same effects.

Example 6>

As described above, the cell container and the lid plate of the sealing plate substrate are made of nickel, stainless steel or nickel-plated steel plate, and the exhaust holes provided on at least one side of the positive electrode terminal made of aluminum rivets are closed. The explosion-proof safety valve closed with a metal foil made of nickel, stainless steel or nickel-plated steel has a problem that it is difficult to break to a predetermined gas pressure unless it is made thinner than the aluminum foil described in Examples 1 to 5. Occurs. However, it is industrially difficult to roll metal foil made of nickel, stainless steel or nickel-steel thinner than aluminum foil. Therefore, for example, a thin horseshoe-shaped pattern was provided in advance on these metal foils that block the exhaust holes of the sealing plate by engraving or the like to verify the effect. That is, the burr generated on the lower surface of the lid plate of the exhaust hole punched from above the nickel-plated steel lid plate with a thickness of 0.6 mm Utilizing and integrating the nickel foil by projection welding and sealing. A thin horseshoe-shaped pattern was provided by engraving so as to be close to the inner circumference of the exhaust hole of the nickel foil. The effect of such marking was evaluated from the variation width of the valve operating pressure. Table 6 shows the results.

Table 6

As is evident from Table 6, by providing a thin pattern on the metal foil in the exhaust hole by means such as engraving, it can be seen that the operating pressure of the explosion-proof safety valve can be reduced and the dispersion can be reduced.

Such a means is effective even when the cell container, the lid plate, and the sealing plate made of metal foil in Examples 1 to 5 are all made of aluminum, particularly when the diameter of the exhaust hole is small. become.

In constructing the prismatic battery, the positive and negative electrode groups were placed on the sealing plate provided with a terminal consisting of a rivet and washer, an explosion-proof safety valve and a liquid injection hole at the center of the sealing plate via a gasket. After welding and fixing the lead plate, the electrode group is inserted and housed in a symmetrical bottomed cell container, and a sealing plate is fitted to the upper edge of the opening of the cell container. In this case, the sealing plate to which the electrode group is connected and fixed is not necessarily left-right symmetric, so that in the subsequent steps, the semi-finished cells whose right and left are different move through the steps. This causes problems in process control and productivity. Therefore, in forming the sealing plate, the lid plate of the sealing plate base material is formed into a band-shaped hoop material, and Parts such as explosion-proof safety valves, liquid injection holes, and terminals are placed continuously, and all of the safety valve pinholes and inspections for the set minimum operating pressure are also performed continuously, and finally cut. If the battery is supplied as it is to the battery assembly process, the semi-finished battery whose left and right arrangement is reversed as described above will not flow to the process, and a highly reliable sealing plate can be manufactured with excellent productivity. Will be possible.

FIG. 4 is an example of a flowchart for continuously manufacturing a sealing plate according to the present invention. Hereinafter, the continuous manufacturing process of the sealing plate will be described with reference to the flowchart of FIG.

First, exhaust holes 7 are punched and provided at regular intervals in an aluminum lid hoop member 2 having a predetermined width and a predetermined thickness (for example, 0.6 mm). Next, in a state where an aluminum foil having a predetermined thickness (for example, 0.03 mm) is overlapped on one surface of the hoop material for the lid plate provided with the exhaust hole 7, the aluminum foil is pressed and integrated between two rollers. Apply cladding (see Fig. 5). During this cladding process, the cover plate is slightly rolled and stretched, so excessive pressing must be avoided.

Next, in the processing in each process, the process of attaching various components, and the final process, positioning is extremely important when cutting and separating individual sealing plates by punching or the like as assembly components of each single cell. Pilot holes 18 for positioning these processes are punched at regular intervals by a punching method.

Next, a center portion of the sealing plate is drawn by a press using a mold so as to be concavely concave downward, and then a rivet insertion hole and a liquid injection hole 13 are opened by a punching method.

The synthetic resin for gasket 4 is molded into the rivet insertion hole by injection molding and fixed integrally with the sealing plate.

Next, the pinholes of the explosion-proof safety valve and the minimum operating pressure of the explosion-proof valve were all tested, and then the sealing agent bron asphalt and mineral oil were added to the central part of the gasket attached by molding to insert the rivet. Apply the paint that has been melted. After the solvent has melted, insert a rivet 5 made of nickel or nickel-plated steel into the center hole of the gasket 4 and crimp the lower end of the rivet while fitting the washer to the lower part of the rivet to form the terminal 5 in a sealed state. (See Figure 6). Each of the above The process proceeds on the basis of pilot holes 18.

As described above, the sealing plate continuously manufactured with the hoop material is conveyed to the battery assembling step and punched out one after another with the pilot hole 18 as a guide. Although the present invention has been described in detail with reference to a thin rectangular lithium ion secondary battery as an example, the present invention is not limited to this battery system. That is, the present invention uses various lithium primary batteries using an organic electrolyte, thionyl chloride as a positive electrode active material, a lithium primary battery in which a solid electrolyte is formed on a metal lithium negative electrode surface, and metal lithium or a lithium alloy as a negative electrode. Like other lithium secondary batteries, it can be applied to all non-aqueous electrolyte batteries in which the cell internal pressure rises abnormally due to an external short circuit, overcharge and overdischarge accompanied by reverse charge.

In addition, the structure of the present invention can be widely applied not only to rectangular batteries, but also to batteries having an oval cross section, a thin cylindrical shape, and a small sealing plate area.

Note that, in the present invention, since the main purpose is to perfect the explosion-proof function in terms of dimensions, it is not possible to prevent a fire accident when current continues to flow such as overcharging. It is assumed that a separate PTC element is built in each cell or battery pack, or that an overcharge and overdischarge prevention circuit is included in a battery pack consisting of multiple cells.

In addition, examples are given of the use of aluminum for bottomed cell containers, lid plates, metal foils, rivets, washers, etc. However, it should be noted that other than metal foil is not limited to pure aluminum. In other words, in order to further reduce the weight and increase the capacity of the battery, for example, a 300-series A1-Mn-based alloy, a 400-series A1-Si-based alloy, It does not prevent thinning of housing materials such as cell containers and lid plates with materials having high mechanical strength and corrosion resistance, such as aluminum alloys such as A0-A1 Mg alloys of 0 series. . Industrial applicability

As described above, the present invention relates to a battery in which a metal-made bottomed cell container is fitted with a sealing plate made of the same metal as the cell container at the upper edge of the opening, and the space between them is sealed by laser welding. The through hole provided in the center of the sealing plate has electrolytic resistance and electrical insulation. A metal rivet that doubles as a terminal is inserted and fixed via a gasket made of synthetic resin with an edge, and at least one exhaust hole is provided between the terminal and the peripheral edge of the sealing plate. This is a non-aqueous electrolyte battery equipped with an explosion-proof safety valve whose exhaust hole is closed by pressing metal foil on the inner surface of the lid plate, which is a material. It can completely prevent the rupture of small batteries whose mold or cross section is oval or the like.

Claims

The scope of the claims

1. A metal sealing plate was fitted to the upper edge of the metal bottomed cell container containing the battery element composed of the positive electrode and the negative electrode and the non-aqueous electrolyte through the separator. In this state, the cell container and the sealing plate are integrated by laser welding to form a sealed opening, and a through hole provided at the center of the sealing plate is made of a synthetic resin made of an electrolytic solution-resistant and electrically insulating. A metal rivet also serving as a terminal is inserted and fixed via a gasket, and at least one exhaust hole is provided between the terminal and a peripheral portion of the sealing plate. A lid serving as a base material of the sealing plate A non-aqueous electrolyte battery provided with an explosion-proof safety valve in which the exhaust hole is closed by press-fitting a metal foil onto at least the peripheral portion of the exhaust hole on the inner surface of the plate.

2. The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte battery is formed by drawing so that the periphery of a through-hole provided in the center of the sealing plate is concavely recessed toward the inside of the cell.

3. The non-aqueous electrolyte battery according to claim 1, wherein the gasket is made of a polyphenylene sulfide resin.

4. The sealing plate is provided with a gasket-integrated terminal and an explosion-proof safety valve in which the exhaust hole is closed with metal foil, and at least one injection hole is provided. After the injection, the injection hole is sealed. 2. The non-aqueous electrolyte battery according to item 1.

5. The non-aqueous electrolyte battery according to claim 1, wherein the shape of the exhaust hole provided in the sealing plate is elliptical.

6. By caulking the lower end of the rivet that also serves as a terminal, the rivet itself is pressurized, and a metal washer that presses and seals the gasket is arranged. From the washer and the electrode group of the same polarity as the washer 2. The non-aqueous electrolyte battery according to claim 1, wherein one of the lead plates is electrically connected.

7. The cell container and the lid plate constituting the sealing plate are made of aluminum or aluminum alloy, the metal foil is made of aluminum, and the rivets and washers are made of nickel or nickel-plated steel. 3. The non-aqueous electrolyte battery according to 1.

8. The lid plate and metal foil that constitute the cell container and the sealing plate are made of nickel, stainless steel or nickel-plated steel, and the rivet and washer are made of aluminum or aluminum alloy. 7. The non-aqueous electrolyte battery according to claim 1, which is made of a lithium alloy.

9. The non-aqueous electrolyte battery according to claim 1, further comprising an explosion-proof safety valve in which a metal foil for closing an exhaust hole of a sealing plate protrudes outwardly from the cell.

10. The non-aqueous electrolyte battery according to claim 1, wherein a thin predetermined pattern is formed on the metal foil that closes the exhaust hole of the sealing plate so as to approach the inner periphery of the exhaust hole.

1 1. Claims 1, 7, and 7 in which the outer surface of the metal foil that has closed the exhaust hole of the sealing plate is coated with a coating made of a non-hygroscopic, chemically stable and plastic organic anticorrosive. 10. The non-aqueous electrolyte battery according to any one of items 8, 9 and 10.

12. A step of providing exhaust holes at regular intervals in a metal hoop material serving as a lid plate, which is the base material of the sealing plate, and pressing and integrating metal foil on one surface of the lid plate material to form a clad plate. A step of closing the exhaust hole with the metal foil, a step of providing through holes at regular intervals in the center of the hoop-shaped clad plate, and a step of molding a synthetic resin having electrolytic resistance and electrical insulation into the through holes. Forming a gasket by molding; forming a coating of a sealant on the gasket surface, inserting a rivet also serving as a terminal into a central hole of the gasket, and caulking and sealing the rivet. In the final process, the hoop material of the sealing plate is cut into individual single-cell sealing plates, and the non-aqueous electrolyte battery sealing material is supplied sequentially to the battery assembly process. Plate manufacturing method.

13 3. After drawing around the through hole provided in the center of the hoop-shaped clad plate made of the cover plate material and the metal foil so as to be concavely recessed from the cover plate material side, mold forming into the through hole 13. The method for producing a sealing plate for a non-aqueous electrolyte battery according to claim 12, wherein the method shifts to a step of forming a gasket according to claim 12.

14. The method for producing a sealing plate for a non-aqueous electrolyte battery according to claim 12, wherein the gasket is made of polyphenylene sulfide.

15. The sealing plate for a non-aqueous electrolyte battery according to claim 12, wherein a through hole is formed at the center of a hoop-shaped clad plate made of a lid plate material and a metal foil, and a liquid injection hole is formed at the same time. Manufacturing method.

16. The method for producing a sealing plate for a non-aqueous electrolyte battery according to claim 12, wherein the shape of the exhaust hole is elliptical.

17. The terminal according to claim 1, wherein the terminal is fixed in a sealed state via a gasket by caulking a lower end of the rivet with a metal washer fitted below the rivet also serving as a terminal. 17. Method for producing a sealing plate for a non-aqueous electrolyte battery.

18. The nonaqueous electrolyte according to claim 12, wherein the hoop-shaped cover plate is made of aluminum or an aluminum alloy, the metal foil is made of aluminum, and the rivet and the washer are made of nickel or nickel-plated steel. 18. A method for manufacturing a battery sealing plate.

19. The non-aqueous electrolyte according to claim 12, wherein the hoop-shaped lid plate material and the metal foil are made of nickel, stainless steel or nickel-plated steel, and the rivet and the washer are made of aluminum or an aluminum alloy. A method for manufacturing a battery sealing plate.

20. The method for producing a sealing plate for a non-aqueous electrolyte battery according to claim 12, wherein the metal foil forming the explosion-proof safety valve by closing the exhaust hole bulges upwardly in a convex shape.

21. The non-aqueous water according to claim 12, wherein a thin predetermined pattern is formed on the metal foil forming the explosion-proof safety valve by closing the exhaust hole so as to be close to the inner periphery of the exhaust hole. A method for producing a sealing plate for an electrolyte battery.

22. The outer surface of the metal foil forming the explosion-proof safety valve by closing the exhaust hole is coated with a coating made of a plastic organic anticorrosive that is chemically stable without moisture absorption. 12. The method for producing a sealing plate for a non-aqueous electrolyte battery according to any one of paragraphs 12, 18, 19, 20, and 21.