JPH09213286A - Thin lithium battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin and light lithium battery with an excellent leaktightness and no moisture permeability, by leading in a generator element from the opening of a thin container, and then, sealing the opening by a lid plate, and jointing the container and the lid plate. SOLUTION: A thin metal plate is molded to form a thin container having an opening on the surface parallel to a generator element. After the generator element is led in from the opening, a lid plate is loaded, and the thin container and the lid body are jointed to seal the opening. The container has a rectangular form, and the thickness of the using metal plate is preferable to be less than 0.4mm. The jointing of the lid plate and the container is carried out by a YAG laser welding and the like. And when necessary, a shield plate is provided between the weld of the thin container and the lid plate, and the generator element. Furthermore, a resin mold is applied after the opening of the container is sealed. Consequently, the mold of the battery can be made in an even thin film.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thin lithium battery.

[0002]

2. Description of the Related Art Recent advances in miniaturization, thinning, and weight reduction of electronic devices have been remarkable, and in the OA field, in particular, the size has been reduced from desktop type to laptop type to notebook type. In addition, the field of new small electronic devices such as electronic notebooks and electronic still cameras has also appeared, and in addition to the miniaturization of conventional hard disks and floppy disks, the development of new memory media, memory cards, is underway. In the wave of miniaturization, thinning, and weight reduction of such electronic devices, high performance is also required for secondary batteries that support such electric power. Under such demands, development of lithium secondary batteries as high energy density batteries replacing lead storage batteries and nickel cadmium batteries has been rapidly advanced. In the lithium secondary battery, in order to widen the electrode area and improve the battery characteristics during current discharge,
A battery is often constructed by spirally winding a positive electrode plate and a negative electrode plate through a separator. Most of the batteries formed in such a case have a cylindrical shape. However, in recent years, many designers of devices using batteries have come to request that the shape of the battery be adapted to the shape of the device. In recent years, prismatic batteries have been developed to meet this demand. This battery case is currently manufactured using a steel plate with nickel plating on the inside and outside or stainless steel. Laser welding is used as one of the effective methods used for sealing the lid of these battery cases. However, in laser welding, the temperature rise at the sealing portion is large, and the internal elements, especially the separator, are melted, causing a short circuit. Further, in recent years, there has been an increasing demand for thinner batteries, but when manufacturing a rectangular container by drawing, there is a limit to the deep drawing processing technology, and it is very difficult to obtain a thin container of several mm. Therefore, its size is naturally decided. That is, when a thin container is manufactured by drawing from the A surface as shown in FIG. 1, it is difficult to manufacture unless the thin container has a thickness of a certain battery size, and a large area of the B surface can be obtained. There wasn't. 7 and 8 show the relationship between the thickness of the battery container and the depth at which it can be drawn. It is easier to squeeze the thicker plate, but the battery thickness is 5
If it is less than mm, it is difficult to sharply squeeze. Therefore, it was very difficult to produce a thin battery having a thickness of 5 mm or less. In addition, the thinner the battery, the more difficult it becomes to insert the battery internal elements into the battery container, and it is necessary to devise such a method that the internal elements are wrapped in a metal cover or the like and inserted (JP-A-6-150974). there were. However, in the above invention, the thinner the battery, the greater the influence of the thickness of the metal cover as a factor of lowering the volumetric energy density, so that it is not practical in a thin battery having a thickness of 5 mm or less, and in a battery having a thickness of 5 mm or less. Was difficult to insert using the above invention. A laminated film has been used as a method for producing a thin lithium battery. That is, an extremely thin and lightweight battery container can be obtained by mounting a power generating element with a laminate film, but a lithium battery must block moisture permeation and may cause gas generation. Was problematic for use in lithium battery systems. Further, in the case of mounting with the film, it is necessary to provide a flange portion at the periphery at the time of sealing and seal by a method such as heat fusion, and the area is considerably larger than that of the battery power generation element and the volume energy density must be small. Didn't get

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and does not use a laminate film which is unsuitable for a lithium battery system and has a thin plate thickness which has never been used before. An object of the present invention is to produce a thin battery container for a lithium battery, which is formed by molding a metal plate, and to provide a thin and lightweight thin battery having excellent liquid leakage resistance and no water permeability.

[0004]

Means for Solving the Problems The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, it is very thin, preferably 0.4 mm or less, more preferably 0.2 to 0.05 m.
a thin container, particularly a rectangular container, which is made of a metal plate having a thickness of about m and has an opening in a plane parallel to the power generating element;
A battery container having a very thin thickness, preferably a plate thickness of 0.3 to 0.02 mm, which is formed by sealing with a lid plate placed in the opening, and a power generating element is introduced into the battery container. By proposing a thin lithium battery, which solves the above-mentioned problems, is excellent in liquid leakage resistance, has no water permeability, and is a very thin lithium battery, for example, 5 mm or less and lightweight,
And we succeeded in obtaining a prismatic lithium battery. The thin lithium battery of the present invention, after introducing the power generation element from the opening of the thin container having an opening in a plane parallel to the electrode, after sealing the opening with a lid plate, the thin lithium battery It can be manufactured by joining a container and a cover plate. The thin container used in the present invention has a structure as shown in FIG. 2, and can be manufactured by drawing from the B surface in the drawing. Regarding the joining of the thin container and the lid plate, in the method of fitting the lid on the thin container (FIG. 3), the thickness of the container increases due to the rising of the joining portion, and the characteristics of the thin container are diminished. The method has a problem that pinholes are generated and liquid leakage occurs unless the dimensional accuracy of the container and the lid plate is extremely high. Therefore, a lid plate having substantially the same outer size as the thin container opening is placed on the thin container (Fig. 4) and heat-welded (Fig. 5) without reducing the characteristics of the thin battery container. We have obtained a thin battery with excellent liquid leakage resistance. The heat welding is preferably laser welding because it can be locally welded and has a relatively small heat effect on the inside and high reliability, and the laser irradiation prevents the laser from entering the inside. Therefore, it is preferable to perform it from above the cover plate surface or obliquely above. However, in the case of performing the laser welding, since the power generation element and the laser welded portion are close to each other, damage to the battery power generation element due to the temperature rise of the laser welding portion becomes a problem. In particular, the separator in the battery element has a melting point near about 150 ° C., and the separator melted during laser welding, causing a short circuit. Therefore, it becomes necessary to reduce the laser intensity during welding as much as possible. However, when the laser power was lowered, welding became insufficient and liquid leakage was observed. In order to solve these problems, the present inventors have developed the following means (1) and (2).

(1) The lid plate for the thin container has a thickness of 0.3 mm or less, which is 0.6 to 0.8 mm.
By using a plate thickness much smaller than that of the battery container, the welding strength can be sufficiently secured even if the laser power is reduced, and the thermal effect during laser welding inside is large. It will be improved. That is, FIG.
As shown in (1), unless the welding strength of the laser is increased from a plate thickness of 0.3 mm or more, the strength of the welded portion becomes insufficient, and increasing the strength of the laser causes a large thermal influence on the internal elements, thus lowering the yield. Carbon dioxide laser, argon laser, nitrogen laser, YAG laser and the like can be mentioned as the kind of laser used for the above-mentioned welding.
The inventors have found that using a laser welder is optimal. In particular, the YAG laser emits the laser in a pulse system, but by welding the laser intensity per pulse in the range of 0.5 to 1.5 J, a lid plate having a plate thickness of 0.1 mm or less can be obtained. It has been found that welding can be performed with sufficient strength, and the thermal effect on the power generation element can be greatly reduced. FIG. 6 shows the relationship between the plate thickness of the lid and the yield of the container when the welding is performed using the YAG laser.

(2) Laser welding between the thin container and the cover plate is performed by providing a heat shield plate between the welding portion between the thin container and the cover plate and the power generating element. It has been found that a prismatic lithium battery having high stability can be obtained without heat being transferred to the power generation element. That is, a heat shield plate is installed so as to cover the peripheral portion of the power generation element from the opening of the thin container having the opening in the thickness direction of the electrode, and then the power generation element is introduced from the opening, and then the power generation element is introduced. By laser-welding the thin container and the lid plate after sealing the opening with the lid plate, the thermal influence on the power generation element can be significantly reduced as compared with the case of (1). Also, when using this heat shield plate, it is preferable that the cover plate has a thickness of 0.3 mm or less. However, by using the heat shield plate as described above, the thermal influence on the power generating element is significantly increased. Since it can be reduced, 0.
The laser welding can be performed even when the diameter exceeds 3 mm, for example, the diameter of 0.3 to 0.8 mm.
After the power generation element was introduced into the thin container having a plate thickness of 0.15 mm, a thickness of 2.8 mm, and an opening of 45 cm ² , the opening had a plate thickness of 0.1 mm as shown in FIG. After sealing with the lid plate, the laser intensity per pulse is 0.5-
When using a YAG laser welding machine of 1.5 J and using a heat shield plate made of SUS having a thermal conductivity and not using it, the thin container and the cover plate are heat welded. FIG. 9 shows the relationship between the distance (mm) from the weld and the temperature rise (° C.) of the power generating element. From the results of FIG. 9, when the heat shield plate is not installed, the internal temperature greatly exceeds 150 ° C. which is the melting point of the separator,
The temperature is lowered by the installation. For example, even if the distance from the weld is 0.5 mm, the temperature is lower than 150 ° C., and no internal short circuit due to melting of the separator is present, and the effect is obvious.

The heat shield plate used in the present invention is shown in FIG.
As shown in 13 and 14, it is in the form of a strip that is bent substantially at a right angle in the battery container along the ridge of the container, and is arranged inside the battery container while covering the traverse line of the power generation element and the vicinity of the traverse line. Is possible. Further, as the heat shield plate, as shown in FIG. 14, it is preferable to provide a corrugated plate, especially on the laser heating surface side. The width and length of the heat shield plate may be within the range that does not cause melting of the separator of the power generation element. Further, the heat shield plate,
The radius of the bent corner is 0.5 mm or more
It is preferable to provide the (R) portion. Such R
By providing the (rounded) portion, it is preferable to form a gap between the laser welded portion and the heat shield plate, whereby the thermal influence on the power generation element can be significantly reduced.

FIG. 10 shows the relationship between the radius of the corners of the heat shield plate and the yield of finished batteries. FIG.
From the results, the yield of the finished battery is lowered when the R (R) of the corner of the heat shield is small, but the yield of the finished battery is greatly increased by setting the size of the R (R) to 0.5 mm or more. And could be substantially 100%. However, as described above, the R (R) is preferably 0.5 mm or more, but when the R (R) is too large, the edge portion of the internal element is crushed, so that the R (R) is preferably 2.0 mm or less. Furthermore, if the heat shield plate itself is made of a material having a low thermal conductivity, it is possible to further improve the thermal influence on the power generation element. That is, the present inventors have examined the relationship between the thermal conductivity of various metals and the yield of the completed battery when those metals are used as a heat shield plate, and as a result, as shown in FIG. When the conductivity is 250 (W / m · K) or less, the heat shielding effect is significantly improved, and the yield of the completed battery is substantially 100%. The heat shielding plate is made of iron, It has been found that stainless steel, nickel chrome alloy, carbon copper, nickel, bismuth and the like are preferable. Further, the thickness of the heat shield plate is usually 0.05 to, though it varies depending on the thermal conductivity of the material forming the heat shield plate.
The range of 0.2 mm is preferable. The thickness is 0.2
If it exceeds 0.3 mm, the energy density becomes low, and if it is 0.
If it is less than 05 mm, the heat shielding effect is low.

The positive electrode active material used in the battery of the present invention is TiS ₂ , MoS ₂ , Co ₂ S ₅ , V ₂ O ₅ , MnO ₂ ,
Transition metal oxides such as CoO _{2 and the} like, transition metal chalcogen compounds and their composites with Li, one-dimensional graphitized compounds which are thermal polymers of organic substances, carbon fluoride, graphite or electrical conductivity of 10 ^-2 S / cm or more. Conductive polymer having specificity, specifically polyaniline, polypyrrole, polyazulene, polyphenylene, polyacetylene,
Polymers such as polyacene, polyphthalocyanine, poly-3-methylthiophene, polypyridine and polyphenylbenzidine, and derivatives thereof can be mentioned. As a negative electrode material used in the battery of the present invention, lithium metal, lithium alloy or carbon material is used. Examples of the carbonaceous negative electrode active material include graphite, pitch coke, synthetic polymer, and a sintered body of natural polymer.
(1) Insulating or semiconducting carbon obtained by firing a synthetic polymer such as phenol or polyimide or a natural polymer in a reducing atmosphere at 400 to 800 ° C., (2) coal, pitch, a synthetic polymer, or a natural polymer. Numerator 800
To a conductive carbon body obtained by firing in a reducing atmosphere at 1300 ° C., (3) Coke, pitch, synthetic polymer, carbon body obtained by firing a natural polymer at a temperature of 2000 ° C. or higher in a reducing atmosphere, Graphite-based carbon bodies such as natural graphite are used. The carbon body is formed into a sheet by a wet papermaking method using the carbon body and a binder, or by a coating method using a coating material in which a suitable binder is mixed with a carbon material. The electrode can be manufactured by supporting the electrode on a current collector as required by a method such as application, adhesion, or pressure bonding.

As the electrolytic solution used in the present invention, an organic non-aqueous polar solvent is used, but an organic non-aqueous polar solvent having an aprotic property and a high dielectric constant is preferable. Specific examples thereof include propylene carbonate, ethylene carbonate, γ-butyl lactone, dimethyl sulfoxide,
Examples thereof include dimethylformamide, dimethoxyethane, dimethoxycarbonate, and diethoxycarbonate, but are not limited thereto. Further, although the low temperature coagulation of ethylene carbonate has conventionally determined the low temperature characteristics of the battery, by mixing propylene carbonate, which is a carbonate-based material similar to ethylene carbonate, and dimethoxy carbonate, coagulation due to low temperature is prevented, The low temperature characteristics can be improved. The electrolyte concentration cannot be unconditionally specified because it varies depending on the type of positive electrode, electrolyte and organic non-aqueous polar solvent used, but it is usually in the range of 0.1 to 10 mol / 1.

Examples of the positive electrode current collector used in the present battery include stainless steel, gold, platinum, nickel, aluminum,
Examples thereof include metal sheets such as molybdenum and titanium, metal foils, metal nets, punching metals, expanded metals, and nets and non-woven fabrics made of metal-plated fibers, metal vapor-deposited wires, metal-containing synthetic fibers and the like. Of these, aluminum and stainless steel are particularly preferable in view of electrical conductivity, chemical stability, electrochemical stability, economic efficiency and workability. Aluminum is more preferable because of its light weight. Furthermore, the surfaces of the positive electrode current collector layer and the negative electrode current collector layer used in the present invention are preferably roughened. By roughening the surface, the contact surface of the active material layer is increased and the adhesion is improved, which has the effect of lowering the impedance of the battery. Further, in the preparation of an electrode using a coating solution, the adhesion between the active material and the current collector can be greatly improved by performing a surface roughening treatment. Examples of the surface roughening treatment include polishing with an emery paper, blasting, and chemical or electrochemical etching, whereby the current collector can be roughened. In particular, in the case of stainless steel, it is preferable to use blasted aluminum, and in the case of aluminum, it is preferable to use etched aluminum. Since aluminum is a soft metal, it is difficult to effectively roughen it by blasting, which causes deformation of aluminum itself. On the other hand, the etching treatment can effectively roughen the surface on the order of micrometer without reducing the deformation of aluminum and its strength itself, and is the most preferable method for roughening aluminum. is there. Usually, the battery container is stainless steel,
Although it is often made of nickel-plated carbon steel or the like, it is not particularly limited as long as it does not affect the corrosion resistance. That is, stainless steel, iron, nickel, aluminum, or alloys thereof can be used.

A separator can be used in the battery of the present invention. As the separator, it is preferable to use a separator having a low resistance to the ion transfer of the electrolyte solution and having an excellent solution retention. Examples of such a separator include a glass fiber, a filter, a non-woven fabric filter made of polymer fibers such as polyester, Teflon, polyflon, and polypropylene, and a non-woven fabric filter made by mixing glass fibers and these polymer fibers. When the rectangular container for a lithium battery of the present invention is applied to a lithium battery using an electrolytic solution, when the gas generation occurs inside due to the thin container plate, the rectangular container may swell even if the amount is small. is there. Therefore, in the present invention, it is preferable to use a solid electrolyte instead of the electrolytic solution. The use of the solid electrolyte eliminates the generation of gas inside and solves the problem that the prismatic lithium battery swells due to gas generation. Examples of solid electrolytes include AgCl, AgBr, A
metal halides such as gI, LiI, RbAg ₄ I ₅ ,
RbAg ₄ I ₄ CN ion conductor and the like can be mentioned. In organic systems, polyethylene oxide, polypropylene oxide, polyvinylidene fluoride, polyacrylonitrile, etc. are used as a polymer matrix to dissolve an electrolyte salt, or a cross-linked product, low molecular weight polyethylene oxide, polyethyleneimine, or an ion of crown ether. A polymer solid electrolyte in which a dissociative group is grafted to a polymer main chain can be mentioned. The gelled polymer solid electrolyte used in the present invention is one in which a polymerizable compound is added to an ordinary electrolytic solution, and polymerization is performed by heat or light to solidify the electrolytic solution. More specifically WO91 /
The one described in 14294 is used. Polymerization of acrylate (eg, methoxydiethyl glycol methacrylate, methoxydiethylene glycol diacrylate) compounds as a polymerizable compound using a polymerization initiator such as benzoyl peroxide, azobisisobutyronitrile, methylbenzoyl formate, benzoin isopropyl ether, etc. Then, the electrolytic solution is solidified. It has been found that the use of a gel-like polymer solid electrolyte in such a solid electrolyte significantly improves ionic conductivity and flexibility. Since the thin battery according to the present invention is made of a very thin material, it may be easily dented or deformed by an external impact. As a result of intensive studies by the present inventors in order to solve such a problem, they have succeeded in significantly improving the strength of the thin battery of the present invention by subjecting it to resin molding after sealing. Examples of the molding resin include polyethylene, polypropylene, polyethylene terephthalate, nylon resin and polyester. Further, as a method for applying these resins, cast coating, air doctor coater, spray coating, dip coating and the like can be mentioned, but as a result of intensive investigations by the present inventors, spray coating is the most suitable as a method used for molding the battery. We have found that this is a system and succeeded in forming a uniform thin film in the battery mold by this system. The details will be described in the following examples.

[0013]

【Example】

Example 1 The positive electrode was composed of LiCoO ₂ , carbon powder as a conductive material, and polyvinylidene fluoride as a binder, at 91: 2: 7.
The paste prepared by mixing in a weight ratio of 1 and using an organic solvent was uniformly applied to both surfaces of a SUS foil having a thickness of 15 μm and dried. The negative electrode was prepared by mixing graphite and fluororesin powder as a binder in a weight ratio of 91: 9, and applying a paste prepared using an organic solvent to a 15 μm-thick copper foil and uniformly coating and drying the paste. Using. Each of these electrodes was punched into a size of 58 mm in width and 75 mm in height, and the positive electrode was wrapped in a bag shape using a porous polypropylene film (trade name Celgard). This separator has 1.8M concentration of LiPF ₆ + 0.2M concentration of LiBF ₄ /
(Propylene carbonate + dimethoxyethane) (volume ratio 7: 3) 80% electrolyte solution, 19.2% ethoxydiethylene glycol acrylate, 0.8% benzoin isopropyl ether mixed polymer solid electrolyte composition is permeated, high pressure It was irradiated with a mercury lamp and gelled. The same gel solution was permeated into the negative electrode as well to perform gelation. After that, positive and negative electrodes were alternately laminated to obtain an internal power generation element.
Case made of nickel-plated 0.2 mm thick steel plate as shown in Fig. 2 (width 60 mm, height 80 m)
m, thickness 2.5 mm), after inserting the internal power generation element, a lid plate having a thickness of 0.1 mm was placed as shown in FIG. 4 and welded as shown in FIG. Laser welding machine is a pulse type Y with output of 100W
An AG laser welder was used, and a case was sent by an NC controller. The bead density of the welded portion was 3 (pieces / mm) as a reference. The welding feed rate was kept constant at 20 (mm / s), and at the same time, the laser oscillation frequency was 60 (pulses / s) and the energy per pulse was 1.0 J. After sealing, the positive and negative electrode terminals of the battery were mended, and liquefied polyethylene resin was sprayed by four spray guns to mold the battery.

Comparative Example 1 The same as Example 1 except that a thin battery comprising a case formed by forming a nickel-plated steel sheet having a thickness of 0.5 mm and a lid having a thickness of 0.5 mm was used.

Comparative Example 2 Same as Example 1 except that the lid has a rising portion of 1 mm as shown in FIG. At this time, the thickness of the container portion was 3.5 mm.

After welding 50 cells of each of Example 1 and Comparative Examples 1 and 2, 18 in a high temperature layer at 60 ° C. and 95 RH% after welding.
After leaving it for 0 days, the rate of occurrence of electrolyte leakage from the joint was examined. In addition, each battery was operated at a constant current of 500 mA.
A charge / discharge cycle test in which the battery was charged to 1 V and then discharged at a constant current of 2.0 mA until the terminal voltage reached 3 V was performed at room temperature for 10 cycles. The capacity density per volume at the 10th cycle was determined. Table 1 shows the results.

[Table 1] As shown in Table 1, in Comparative Example 1, since the lid was thick, the reliability of laser welding was low. Leakage was observed from 15% of the batteries 180 days after leaving, and in Comparative Example 2, the lid was Since an extremely high accuracy was required, a leak was observed from 11% of the batteries, but it was not detected at all in Example 1 according to the present invention, and there was no electrolyte leak, that is, no welding defect.

Example 2 A positive electrode was made of LiCoO ₂ , carbon powder as a conductive material, and polyvinylidene fluoride as a binder, at 91: 2: 7.
The paste prepared by mixing in a weight ratio of 1 and using an organic solvent was uniformly applied to both surfaces of a SUS foil having a thickness of 15 μm and dried. The negative electrode was prepared by mixing graphite and fluororesin powder as a binder in a weight ratio of 91: 9, and applying a paste prepared using an organic solvent to a 15 μm-thick copper foil and uniformly coating and drying the paste. Using. Each of these electrodes was punched into a size of 58 mm in width and 75 mm in height, a positive electrode was wrapped in a bag using a porous polypropylene film (trade name Celgard), and then positive and negative electrodes were alternately laminated to form an internal power generation element. Got This internal power generation element has 1.8M concentration of LiPF ₆ + 0.2M concentration of LiBF ₄ /
An 80% electrolytic solution of (propylene carbonate + dimethoxyethane) (volume ratio 7: 3) was permeated. A case in which a 0.2 mm thick steel plate plated with nickel is formed as shown in Fig. 2 (width 60 mm, height 80 mm, thickness 2.5).
mm) and after inserting the internal power-generating element, it is bent at a right angle as shown in FIG. 12, and the radius of the bent portion is molded to 0.5 mm,
As shown in FIG. 13, a stainless steel thin plate (heat shield plate) having a corrugated upper surface with a thickness of 0.1 mm as shown in FIG. 14 is installed on the peripheral portion of the power generating element as shown in FIG. It was placed and welded as shown in FIG. Laser welding machine output 10
A 0 W pulse type YAG laser welder was used, and a case was sent by an NC controller. The bead density of the welded portion was 3 (pieces / mm) as a reference.
The welding feed rate was kept constant at 20 (mm / s), and at the same time, the laser oscillation frequency was 60 (pulses / s) and the energy per pulse was 1.0 J. Fifty of each of these batteries were left for 180 days in a high temperature layer of 60 ° C. and 95 RH% after welding, and the leakage rate of the electrolytic solution from the joint was examined, but no leakage was found. In addition, each battery is charged at a constant current of 500 mA up to 4.1 V, and then discharged at the same constant current of 2.0 mA until the terminal voltage reaches 3 V. A charge-discharge cycle test is performed at room temperature for 10 cycles. When carried out, the capacity density per volume at the 10th cycle was 51 mAh / cc.

The embodiments of the present invention will be described below. 1. A thin container for a lithium battery, which is formed by molding a metal plate having a plate thickness of 0.2 mm or less. 2. In a thin lithium battery in which a power generating element is introduced into a battery container formed by molding a metal plate, the battery container is placed in the thin container having an opening in a plane parallel to the power generating element and the opening. A thin lithium battery, which is formed by sealing with a lid plate. 3. A thin container with an opening on the surface parallel to the power generation element,
The lithium battery of 1 or 2 which is prismatic. 4. 2. The metal plate having a thickness of 0.2 mm or less
~ 3 thin lithium batteries. 5. The above-mentioned 2 in which the lid plate is a metal plate having a thickness of 0.1 mm or less.
To 4 thin lithium batteries. 6. The thin lithium battery according to any one of 2 to 5 above, wherein a heat shield plate is provided between the welding portion of the thin container and the cover plate and the power generating element. 7. The thin lithium battery according to any one of 2 to 6 above, wherein the outer dimensions of the thin container and the cover plate are the same.

8. The thin lithium battery according to any one of 2 to 7 above, wherein the thin container and the lid plate are joined by laser welding. 9. 8. The thin lithium battery according to 8 above, wherein the laser welding is performed by a YAG laser welding machine. 10. 8. The thin lithium battery according to 8 to 9, wherein the laser intensity for laser welding is 0.5 to 1.5 J per pulse. 11. 11. The thin lithium battery according to 2 to 10 above, wherein the heat shield plate has a wavy shape. 12. The heat shield is made of metal and its thermal conductivity is 250.
11. The thin lithium battery according to 11 above, which is (W / m · K) or less. 13. The thin lithium battery 2 to 12, which is resin-molded after sealing. 14． The thin lithium battery of the above 2 to 13 having a thickness of 5 mm or less. 15. 2 to 14, wherein the electrolyte layer is a solid electrolyte layer
Thin lithium battery. 16. In a thin container formed of a metal plate and having an opening in a plane parallel to the power generating element, a lid plate is placed after introducing the power generating element from the opening, and the rectangular container and the lid are placed. The method for producing a thin lithium battery according to any one of 2 to 15 above, characterized in that the opening is sealed by joining with a plate, and if necessary, a resin mold is applied after sealing. 17． 17. The method for manufacturing a thin lithium battery according to 16, wherein the thin container having an opening in a plane parallel to the power generating element is rectangular. 18. 18. The method for manufacturing a thin lithium battery according to the above 16 to 17, wherein resin molding is performed by spray coating. 19. 19. The method for manufacturing a thin lithium battery according to 16 to 18, wherein the thin container and the lid plate are joined by a YAG laser welding machine. Laser intensity per 20.1 pulse is 0.5 to 1.5
The method for producing a thin lithium battery according to any one of 16 to 19 above, wherein J is J.

[0020]

【The invention's effect】

(1) According to the present invention, the battery container has an opening in the thickness direction of the electrode, the battery internal element is inserted through the opening, and the lid plate is placed thereon, and the opening is closed by the lid plate. This made it possible to produce a thin battery having a thickness of 5 mm or less in a large area. Further, in a battery including a thin outer container, particularly the prismatic outer container and an electrode body that is a power generating element inserted into the outer container, an opening is provided in a plane parallel to the power generating element After inserting the power generating element, a lid plate, in particular, a lid plate having the same outer dimensions as the outer dimensions of the opening is placed, and then the battery container and the lid plate are laser-welded, particularly laser-welded from above the lid plate. As a result, by sealing, it has been impossible to manufacture a thin battery having a large area on the B-side in FIG. 1, but it is possible to obtain it by squeezing as shown in FIG. became. Furthermore, the laser intensity per pulse of the laser welding is 0.5 to
Plate thickness is 0.1m by welding in the range of 1.5J
A lid plate of m or less can be welded with sufficient strength, and the thermal effect on internal elements can be greatly improved. (2) According to the present invention, in a battery provided with a thin container, in particular, the prismatic outer container, and an electrode body which is a power generation element inserted into the container, the container has an opening in a surface direction of the electrode. After inserting the power generation element having a metal thin plate as a heat shield plate at the peripheral edge from the opening, the lid plate is placed, and the lid plate is attached to the opening of the thin container. By sealing with laser welding, it was possible to obtain a battery that had no thermal effect on the battery power generation element. (3) Since the heat shield plate is bent at a right angle along the container and the radius of the corner is 0.5 mm or more, a gap is formed between the laser welded portion and the thin plate, thereby heat to the internal elements. The impact could be reduced significantly. Further, by using a heat shield plate having a corrugated shape as shown in FIG. 14 as the heat shield plate, the effect becomes extremely large. The thermal conductivity of the heat shield plate is 250 (W / mK).
The heat shielding effect can be further improved by the following. (4) By using a solid electrolyte instead of the electrolytic solution, gas generation inside is eliminated, and the problem that the prismatic lithium battery swells due to gas generation can be solved. (5) After sealing, a resin mold treatment was performed to significantly improve the strength of the thin battery. In addition, they found that spray coating was the most suitable method used for the mold, and succeeded in forming the battery mold into a uniform thin film by this method.

[Brief description of drawings]

FIG. 1 is a perspective view of a thin container.

FIG. 2 is a perspective view of a thin container.

FIG. 3 is a diagram showing laser welding of a thin container and a lid plate having a rising portion.

FIG. 4 is a diagram showing laser welding of a thin container having the same outer dimensions and a lid plate.

FIG. 5 is a diagram showing laser welding of the thin container and the cover plate according to the first embodiment.

FIG. 6 is a graph showing the relationship between the plate thickness of the lid and the yield.

FIG. 7 is a graph showing the relationship between the thickness of the battery container and the depth that can be drawn.

FIG. 8 is a graph showing the relationship between the thickness of the battery container and the squeezable depth.

FIG. 9 is a graph showing a thermal effect at the time of laser welding.

FIG. 10 is a graph showing the relationship between the corner radius of the heat shield plate and the yield.

FIG. 11 is a graph showing the relationship between the thermal conductivity of the heat shield plate and the yield.

FIG. 12 is a perspective view of a heat shield plate.

FIG. 13 is a cross-sectional view of a prismatic lithium battery in which a heat shield plate is arranged.

FIG. 14 is a cross-sectional view of a heat shield plate.

[Explanation of symbols]

 1 Battery Container 2 Lid 3 Terminal 4 Bead 5 Laser 6 Thin Plate (Heat Shield) 7 Internal Power Generation Element A Surface for Drawing B Surface for Drawing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Beppu Akinen, 1-3-3 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (15)

[Claims] 1. A thin lithium battery in which a power generating element is introduced into a battery container formed by molding a metal plate, wherein the battery container has a thin container having an opening in a plane parallel to the power generating element, and the opening. A thin lithium battery, characterized in that it is formed by sealing with a lid plate placed on the section. 2. The lithium battery according to claim 1, wherein the thin container having an opening in a plane parallel to the power generating element is prismatic. 3. The thin lithium battery according to claim 1, wherein the metal plate has a plate thickness of 0.4 mm or less. 4. The thin lithium battery according to claim 1, 2 or 3, wherein the cover plate is a metal plate having a plate thickness of 0.3 mm or less. 5. The thin shape according to claim 1, 2, 3 or 4, wherein the thin plate and the lid plate having the same outer size as the outer dimension of the opening of the thin container are welded by laser welding. Lithium battery. 6. The thin lithium battery according to claim 1, wherein the laser welding is performed by a YAG laser welding machine. 7. A heat shield plate is provided between a welded portion of a thin container and a cover plate and a power generating element.
Or the thin lithium battery described in 6. 8. The thin lithium battery according to claim 7, wherein the heat shield plate has a wavy shape. 9. The thin lithium battery according to claim 7, wherein the heat shield plate is made of metal and has a thermal conductivity of 250 (W / m · K) or less. 10. The thin lithium battery according to claim 1, wherein the resin mold is applied after sealing. 11. The method according to claim 1, wherein the thickness is 5 mm or less.
The thin lithium battery according to 3, 4, 5, 6, 7, 8, 9 or 10. 12. A thin container formed by molding a metal plate and having an opening in a plane parallel to the power generation element, and after mounting the power generation element through the opening, the lid plate is placed, and the thin plate is placed. The opening portion is closed by joining a shaped container and the lid plate to each other.
9. A method for manufacturing a thin lithium battery according to 9, 10, or 11. 13. The method of manufacturing a thin lithium battery according to claim 12, wherein the thin container having an opening in a plane parallel to the power generating element is rectangular. 14. The method for manufacturing a thin lithium battery according to claim 12, wherein the outer size of the lid plate is the same as the outer size of the opening. 15. The method according to claim 12, wherein the thin container and the lid plate are joined by a YAG laser welding machine.
13. The method for producing a thin lithium battery according to 13 or 14.