JP2004363087A - Battery and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery of low cost and high productivity which is suitable for a middle load application. <P>SOLUTION: Sheet-like mixture layers 20 and 21 are arranged on both sides of a collector 22 to constitute an electrode 8 (positive electrode) 1 of laminating structure. The electrode 1 and its counter electrode (negative electrode) 2 are wound with a separator in between while displacement in winding direction occurs between the collector of the electrode and the sheet-like mixture layer. The roll is housed in a battery vessel 2 (package can). The collector of the electrode 1 having the laminated structure is a plain woven wire net, metal foil, expanded metal, lath mesh, or punching metal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a battery suitable for medium load use.

  As the cylindrical battery, a wound type battery for heavy load such as a camera and a bobbin type battery for high capacity but light load such as a backup for commercial use have been commercialized. Of these, bobbin type batteries have a simple structure and can be manufactured at low cost, but have a small electrode area and poor load characteristics.

  For a heavy-duty wound-type battery, for example, using a conductor, such as metal or carbon, as a current collector, a foil, a net, a woven fabric, or a non-woven fabric, apply an active material mixture thereto, and press-bond. It is manufactured by forming a long electrode by, for example, integrating and winding this and a counter electrode through a separator (see Patent Document 1). However, this winding method involves a problem that the structure is complicated because a thin long electrode is wound therein, and it is difficult to manufacture the electrode, and the cost is high.

  Further, among the non-aqueous primary batteries, the lithium-thionyl chloride battery also has a bobbin structure, which also has a drawback of poor load characteristics. As a recent application of batteries, for example, information communication and the like that require a current of several tens mA to about 300 mA have increased, but the above batteries are not suitable for such medium-load applications.

Japanese Utility Model Publication No. 6-6460 (pages 2-3)

  In view of such circumstances, an object of the present invention is to provide an inexpensive and highly-productive battery suitable for medium-load applications.

  In a wound-type battery, a long electrode configuration requires a large number of windings, which inevitably makes the electrode thin and long. In this case, it is difficult to obtain winding accuracy due to variations in the thickness of the electrode. And the ratio of separators and the like increases, leading to an increase in cost and difficulty in supplying inexpensive products. On the other hand, when the electrodes are made shorter and thicker, the ratio of the current collector and the separator decreases, the active material can be filled more, the capacity can be increased, and the winding deviation can be reduced, which is advantageous in productivity and cost. .

  However, when a thick electrode is wound, a large stress is applied to the electrode. Therefore, in a conventional electrode in which the current collector and the active material mixture are completely integrated, the active material mixture peels or cracks. Or cause troubles such as a decrease in capacity or a short circuit.

  The present inventors have conducted intensive studies in consideration of the above points, and as a result, wound an electrode having a laminated structure in which sheet-shaped mixture layers prepared in advance were arranged on both sides of a current collector, together with a counter electrode and a separator. When rotating, by causing a displacement in the winding direction between the current collector of the electrode of the laminated structure and the sheet-shaped mixture layer, the stress applied to the electrode of the laminated structure is greatly reduced. Further, it was found that even if the thickness of the mixture layer was increased, defects such as peeling and cracks did not occur, and an inexpensive battery suitable for medium load applications in which poor winding and short-circuiting were unlikely to occur was found.

The present invention has been completed based on such findings.
That is, the present invention provides an electrode having a laminated structure in which a sheet-shaped mixture layer is disposed on both sides of a current collector without being substantially fixed to the current collector, a counter electrode of the electrode, and a gap between them. The present invention relates to a battery, wherein a wound body formed by spirally winding an intervening separator is accommodated in a battery container. In particular, the present invention relates to the battery having the above-described configuration, in which the current collector is a plain woven metal mesh, a metal foil, an expanded metal, a lath mesh, or a punching metal in the electrode having the above-described laminated structure.

  Further, according to the present invention, in the electrode having the above-mentioned laminated structure, in the battery having the above-described structure, only the end portion on the winding center side is fixed to the current collector, and the end portion of the current collector is a sheet. The battery of the above configuration, which is located so as not to be exposed from the end of the mixture layer, the battery of the above configuration, in which the width of the current collector is smaller than the width of the sheet mixture layer, the porosity of the sheet mixture layer Is 35 to 50%, the battery having the above-described configuration in which the sheet-shaped mixture layer has a thickness corresponding to 4 to 10% of the battery inner diameter, and the sheet-shaped mixture layer located inside the current collector. The battery of the above configuration, wherein the length before winding is shorter than the length of the current collector, and the length of the sheet-shaped mixture layer located outside the current collector before winding is longer than the length of the current collector. A non-aqueous electrolyte having a wound body in which the entire inner and outer surfaces of the body are covered with a sheet-shaped mixture layer and using lithium perchlorate as a solute The battery of the above configuration, the battery of the above configuration, in which the number of turns of the wound body is more than 1 round and 3 or less, the battery of the above configuration, wherein the counter electrode is a metal or a metal alloy, and the above, wherein the counter electrode is lithium or a lithium alloy. A battery having the above configuration can be provided.

  Further, the present invention provides an electrode having a laminated structure in which a sheet-shaped mixture layer is disposed on both sides of a current collector, and the positional deviation in the winding direction between the current collector and the sheet-shaped mixture layer is reduced. It is another object of the present invention to provide a method for producing a battery, characterized in that the electrode is wound together with its counter electrode and a separator interposed therebetween to form a wound body, and this is housed in a battery container.

  In one embodiment of the method for manufacturing a battery, a step of arranging a sheet-shaped mixture layer on both sides of the current collector in a state not being substantially fixed to the current collector to form an electrode having a stacked structure; Winding the electrode and its counter electrode and a separator interposed therebetween, while causing a displacement in the winding direction between the current collector of the electrode having the laminated structure and the sheet-shaped mixture layer, And a step of accommodating the wound body obtained by the winding step in a battery container.

  As described above, in the present invention, a sheet-shaped mixture layer prepared beforehand is arranged on both sides of the current collector to form an electrode having a laminated structure, and when this and its counter electrode are wound via a separator, the above-described laminated Between the current collector of the electrode of the structure and the sheet-shaped mixture layer, by such a configuration as to cause displacement in the winding direction, even if the mixture layer is thickened, such as peeling and cracking It is possible to provide a low-cost and high-productivity battery suitable for medium-load applications that does not cause any trouble and is unlikely to cause winding failure or short circuit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a battery according to an embodiment of the present invention. In FIG. 2, a battery 1 has an outer can 2, which is a battery container, a positive electrode 3 (electrode having a laminated structure) and a negative electrode 4 loaded in the outer can 2, and a closure for sealing an upper opening of the outer can 2. Structure. The positive electrode 3 and the negative electrode 4 are housed in the outer can 2 together with the electrolytic solution as a wound body 6 wound with a separator 5 interposed therebetween.

  The sealing structure includes a cover plate 8 fixed to the inner peripheral edge of the upper opening of the outer can 2, and a terminal body attached to an opening formed in the center of the cover plate 8 via a rubber insulating packing 9. 10 and an insulating plate 11 arranged below the cover plate 8. The insulating plate 11 is formed in the shape of an upwardly opening round plate with an annular side wall 13 erected on the periphery of a disk-shaped base portion 12, and a gas passage 14 is opened in the center of the base portion 12. I have. The cover plate 8 is fixed to the inner peripheral edge of the upper opening of the outer can 2 by a crimp seal via laser welding or packing while being received by the upper end of the side wall 13. A thin portion may be provided on the lid plate 8 or the can bottom 2a of the outer can 2, and a vent may be provided as a countermeasure when the internal pressure is rapidly increased. The positive electrode 3 and the lower surface of the terminal body 10 are connected by a positive electrode lead body 15, and the negative electrode terminal 4 and the inner surface of the outer can 2 are connected by a negative electrode lead body 16.

  In FIG. 1 showing a cross-sectional view showing an example of the battery of the present invention, reference numeral 3 denotes a positive electrode having a laminated structure in which sheet-shaped mixture layers 20 and 21 are arranged on both sides of a current collector 22; 3 and a negative electrode 2 as a counter electrode thereof are wound via a separator 5 to form a wound body 6.

  FIG. 3 is a cross-sectional view showing a state before the winding of the electrode (positive electrode) 3 having the above-mentioned laminated structure, and the sheet-shaped mixture layer 20 located inside the current collector 22 on both sides of the current collector 22. And the sheet-shaped mixture layer 21 located on the outside are arranged without being fixed to the current collector 22. With such a configuration, the flexibility and flexibility of the positive electrode 3 can be secured well. Thus, it is possible to effectively prevent the active material mixture from falling off or peeling or to generate cracks at the time of winding, and it is possible to reliably suppress the occurrence of short circuit and poor conductivity.

  As shown in FIG. 1, at the time of the above-mentioned winding, at the winding start end S which is the end of the stacked structure of the positive electrode 3 on the winding center side, the sheet-shaped mixture layers 20 and 21 are previously collected by the current collector 22. (See FIG. 4C). More specifically, after the three members are overlapped so that the current collector 22 is several mm inside the sheet-shaped mixture layers 20 and 21, 3 to 10 mm is pressed from the end in the length direction by pressing. You may keep it. In other words, the winding may be performed in a state where the sheet-shaped mixture layers 20 and 21 are not fixed to the current collector 22 but are simply in contact with each other, but the sheet-shaped mixture layer 20 at the winding start end S may be wound. 21 is fixed to the current collector 22, and in other parts, the sheet-shaped mixture layers 20 and 21 are not fixed to the current collector 22 but are simply in contact with the current collector 22, so that the layers at the time of winding The setting becomes easy, and the occurrence of winding deviation in the width direction of the electrode (the direction orthogonal to the winding direction) can be prevented, so that the wound body 6 can be configured with high accuracy.

  In addition, only the winding start end S is fixed, for example, when the current collector 22 is formed of a porous current collector such as a net, only the ends of the sheet-shaped mixture layers 20 and 21 arranged on both sides thereof. Is pressed, and the active material mixture is buried in the mesh of the current collector 22 with good adhesion. However, the fixing means only at the end is not limited to this, and any other means can be adopted.

  By thus being wound around one end of the positive electrode 3 having a laminated structure as a center, unlike the conventional winding method, the whole of the positive electrode 3 having the laminated structure is press-bonded or the like. Unlike the case where the current-collecting layer 20 and 21 provided on both sides of the current collector 22 are considerably thickened, unlike the case where the current-collecting layer is It is possible to obtain an inexpensive and highly-productive battery suitable for medium-load applications without any problems such as peeling or cracking from the film, and being able to be wound very well and without problems such as short circuit. .

  In the positive electrode 3 having a laminated structure, the current collector 22 may be made of a metal or carbon conductor. Specifically, the current collector 22 may be a plain woven wire mesh made of stainless steel 316, 430, or 444, a metal foil, an expanded metal, or the like. A lath net or a punching metal may be used. From the viewpoint of preventing short circuit, the current collector 22 is preferably configured so that both ends are not exposed from the ends of the sheet-shaped mixture layers 20 and 21. It is desirable that the width is smaller than the width of the mixture layers 20 and 21. In this case, the end of the current collector 22 is preferably accommodated in the mixture layer within a range of 5 mm from the ends of the sheet-like mixture layers 20 and 21.

  Further, in the positive electrode 3 having a laminated structure, when the current collector 22 is formed of a porous current collector such as a net, there is a gap that remains inside the current collector 22 in the state of the wound body 6. That is, the porous current collector itself has a mesh-shaped gap before the sheet-shaped mixture layers 20 and 21 are provided. However, among the gaps, the gap is provided at a portion of 20 to 90% of the thickness of the current collector from the center of the porous current collector, and the other portions are formed of a sheet-shaped mixture by the pressure during winding. The layers are buried.

  Preferably, a paste-like conductive agent is applied to the surface of the current collector 22. In the case where the net-like current collector 22 having a three-dimensional structure is used as the current collector 22, similar to the case where a material consisting essentially of a flat plate such as a metal foil is used, the current collection effect is significantly improved by applying a conductive material. Is recognized. This is because not only the path in which the metal part of the net-like current collector 22 directly contacts the sheet-like mixture layers 20 and 21 but also the path through the conductive material filled in the mesh are effectively used. It is presumed to be due to

  Specific examples of the conductive material include a silver paste and a carbon paste. In particular, the carbon paste requires less material cost than the silver paste, and can provide a contact effect substantially equal to that of the silver paste. Therefore, the carbon paste is suitable for reducing the manufacturing cost of the nonaqueous electrolyte battery. As the binder of the conductive material, it is desirable to use a heat-resistant material such as water glass or an imide-based binder. This is because the moisture in the sheet-shaped mixture layers 20 and 21 is removed at a high temperature exceeding 200 ° C.

  The sheet-shaped mixture layers 20 and 21 provided on both sides of the current collector 22 usually include a positive electrode active material, a conductive auxiliary agent, and a binder. It is manufactured by molding into a sheet having a predetermined thickness by a pressurizing method, a combination method thereof, or the like.

  As the positive electrode active material, manganese dioxide, carbon fluoride, lithium cobalt composite oxide, spinel type lithium manganese composite oxide, or the like is used. As the conductive assistant, one selected from graphite, carbon black, acetylene black, and Ketjen black, or a composite of two or more kinds is used, but Ketjen black is preferably used as a main component. As the binder, polytetrafluoroethylene dispersion, powdered polytetrafluoroethylene, a rubber-based binder, or the like is used, and it is preferable to use polytetrafluoroethylene dispersion.

  The sheet mixture layers 20 and 21 preferably have a porosity of 35 to 50%. If the porosity is too small, the mixture density becomes too high, the flexibility is lost, and cracks are likely to occur during winding. On the other hand, if the porosity is too large, the battery capacity decreases. Further, it is desirable that the sheet-shaped mixture layers 20 and 21 have a thickness corresponding to 4 to 10% of the inner diameter of the battery for medium load use.

  If the thickness of the sheet-shaped mixture layers 20 and 21 is too thin, the number of windings increases, and it takes time and effort to wind the windings, which may cause a winding shift and cause a short circuit. Conversely, if the thickness is too large, the pulse discharge characteristics deteriorate. Battery characteristics are easily damaged.

  When such a relatively thick sheet-shaped mixture layer 20/21 is used and the negative electrode 4 is wound therearound, the current collector 22 and the sheet-shaped mixture layer 20/21 are wound at the time of winding. In consideration of the resulting positional deviation in the winding direction, the length of the sheet-shaped mixture layer 20 that is located inside the current collector 22 among the sheet-shaped mixture layers 20 and 21 before the winding is usually Each length is appropriately set so that the length of the sheet-shaped mixture layer 21 positioned outside the current collector 22 before winding is shorter than the length of the current collector 22 so as to be longer than the length of the current collector 22. Is done.

  That is, as the winding proceeds, the portion of the sheet-shaped mixture layer 20 except for the vicinity of the center of the winding shifts outward (in the direction opposite to the center of the winding) with respect to the current collector 22, while The portion of the mixture layer 21 other than the vicinity of the center of the winding shifts inward (in the direction of the center of the winding) with respect to the current collector 22. The amount of this shift increases as the distance from the center of the winding increases. Therefore, by appropriately setting the lengths of the sheet-shaped mixture layers 20 and 21 and the current collector 22, as shown in FIG. Even if it is exposed between the layers 20 and 21, after winding, it can be accommodated inside the sheet-shaped mixture layers 20 and 21 as shown in FIG.

  When the entire inner and outer surfaces of the current collector 22 are covered with the sheet-shaped mixture layers 20 and 21, when exposure to the surface of the current collector 22 is eliminated, an electrolytic solution using lithium perchlorate as a solute is used. Even when an electrolytic solution having high conductivity is used like a liquid, it is possible to prevent the dendrite-like lithium from depositing on the surface of the current collector 22, thereby preventing abnormal discharge of the nonaqueous electrolyte battery. .

  That is, the abnormal discharge of the nonaqueous electrolyte battery according to the present invention is due to a short circuit between the current collector 22 and the negative electrode 4 via dendritic lithium deposited on the surface of the current collector 22, If the entire inner and outer surfaces of the current collector 22 are covered with the sheet-shaped mixture layers 20 and 21, even when a high-conductivity electrolyte is used, the problem of precipitation of dendritic lithium on the surface of the current collector 22 is as follows. Therefore, no short circuit occurs between the current collector 22 and the negative electrode 4, and abnormal heat generation of the battery can be reliably prevented.

  Here, "the entire inner and outer surfaces of the current collector 22 are covered with the two sheet-shaped mixture layers 20 and 21" refers to the winding start end S and the winding end E as shown in FIG. Not only is the current collector 22 covered with the two sheet-shaped mixture layers 20 and 21, but also as shown in FIG. 2, the width of the current collector 22 (the length in the vertical direction in FIG. 2) is a sheet. The width of both ends of the current collector 22 in the width direction is set to be smaller than the width of the mixture layers 20 and 21, and the widthwise ends of the current collector 22 are located more inward than the sheet-form mixture layers 20 and 21. It means that it is covered with the sheet-shaped mixture layers 20 and 21.

  If the end portions of the sheet-shaped mixture layers 20 and 21 at the winding end portion E are formed to be longer than the end portions of the current collector 22, the winding end portion E of the current collector 22 can be exposed. Can be reliably blocked. Then, the extension of the sheet-shaped mixture layers 20 and 21 with respect to the current collector 22 is set to 0.5 mm or more and 1.5 mm or less. When the extension dimension is less than 0.5 mm, the current collector 22 related to the winding end portion E may be exposed on the surface, and when the extension dimension exceeds 1.5 mm, the current collector 22 is not backed by the current collector 22. Since the sheet-shaped mixture layers 20 and 21 become longer, improvement in discharge capacity cannot be expected.

  As the separator 5, a nonwoven fabric such as polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, or polyphenylene sulfide, or a microporous film is used.

  The thickness is not particularly limited, but is usually preferably 50 to 200 μm for a nonwoven fabric and 10 to 50 μm for a microporous film.

  The negative electrode 4 is formed in a thin plate shape (foil shape), and examples of the material include lithium metal, alloys such as lithium and aluminum, and carbon materials such as graphite. The thickness of the negative electrode 4 is usually preferably 0.2 to 0.6 mm. As shown in FIG. 1 and FIG. 4 (b), the negative electrode 4 is formed by laminating two short and long negative electrodes 4a and 4b. The rotator 6 is manufactured. Note that a current collector such as a copper foil can be used as the base material for the negative electrode 4.

  Such a negative electrode 4 and the positive electrode 3 are wound with a separator 5 interposed therebetween. As shown in FIG. 1, the wound body 6 is defined by a winding start end S and a winding end E of the positive electrode 3. When the number of windings exceeds 1 round and 3 rounds or less, preferably 2 rounds or less, the whole is formed in a substantially cylindrical shape, and the winding operation is easy and low cost, and the capacity suitable for medium load use is obtained. Can be manufactured. FIG. 1 shows an embodiment in which the number of windings is about 1.7 turns.

  The wound body 6 can be manufactured by a procedure as shown in FIG. First, as shown in FIG. 4 (a), the separator 5 is wound around the core 25 in one turn. Next, as shown in FIG. 4B, the negative electrode 4 is inserted from one layer portion of only the short length 4a toward the winding core 25 and wound around the separator 5 one round (see FIG. 4C). Subsequently, as shown in FIG. 4C, the positive electrode 3 is placed on the negative electrode 4 via the separator 5 and wound around the core 25. Here, the positive electrode 3 is wound from the side of the winding start end S to which the two sheet-shaped mixture layers 20 and 21 and the current collector 22 are fixed, and the separator 5 is placed on the long negative electrode 4b. Is wound in a state of being placed via the After the end of the winding, the separator 5 covers the outermost periphery. The wound end portion E of the separator 5 is fixed with a fixing tape. From the above, a wound body 6 having the form shown in FIG. 1 can be obtained.

  The outer can 2 as a battery container is a bottomed cylindrical container made of iron or stainless steel, and its lid is sealed with a crimp seal via laser welding or packing. Further, the sealing may be performed by caulking or glass hermetic sealing of the terminal portion. Further, usually, a thin portion is provided on the lid or the bottom of the can, and a vent is provided as a countermeasure when the internal pressure is rapidly increased.

A non-aqueous electrolyte is injected into the outer can 2 which is a battery container. For the non-aqueous electrolyte, a mixture of a cyclic carbonate such as propylene carbonate and ethylene carbonate and a chain ether such as dimethoxyethane is used as a solvent, and LiPF ₆ , LiClO ₄ , and LiCF ₃ SO ₃ are used as solutes. , (CF ₃ SO ₂ ) ₂ NLi or the like dissolved at a ratio of 0.3 to 1.5 mol / liter. Among them, lithium perchlorate (LiClO ₄ ) has a high conductivity and is preferable for obtaining an effect of improving battery characteristics.

When an electrolytic solution having high conductivity such as lithium perchlorate is employed, the electrode area defined by the area of the sheet-shaped mixture layers 20 and 21 can be set to 25 cm ² or more and 60 cm ² or less. Such an electrode area has a relatively small value for this kind of wound electrode body, but when an electrolytic solution having high conductivity such as lithium perchlorate is employed, a good discharge capacity can be obtained. If it exceeds 60 cm ² , the filling property of the active material is reduced, and the light load capacity is reduced.

  The non-aqueous electrolyte battery having the above configuration includes a lithium-manganese dioxide battery, a lithium-fluorocarbon battery, a lithium ion battery, and the like.

  The battery of the present invention includes, in addition to the nonaqueous electrolyte battery having the above configuration, other primary batteries such as a dry battery and an alkaline manganese battery, and further includes a nickel-cadmium battery, a nickel-hydrogen battery, and a lithium ion battery. Secondary batteries are also included.

A known positive electrode active material (positive electrode mixture), a negative electrode active material (negative electrode mixture), an electrolytic solution, and the like are appropriately selected and used depending on each of these battery configurations. Although FIG. 1 shows an example in which the configuration of the present invention is applied to the positive electrode, it goes without saying that the same can be applied to the negative electrode.
(Example)

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In this embodiment, a lithium-manganese dioxide battery (CR battery) will be described as an example. In the following, the porosity of the sheet-shaped mixture layer is determined as follows.

<Measurement of porosity>
The true specific gravity of manganese dioxide, Ketjen black and polytetrafluoroethylene constituting the sheet mixture layer was 4.5 g / cm ³ , 2.0 g / cm ³ , and 2.2 g / cm ³ , respectively. The total X (g) of the calculated weights of the respective constituent elements contained in the sheet-shaped mixture layer per volume is calculated, and the difference from the actual density Y (g) of the sheet-shaped mixture layer is obtained by [(X− Y) / X] × 100, and the porosity (%) was determined.

<Positive electrode manufacturing method>
(Blending) Dry mixing was performed for 5 minutes using a planetary mixer at a ratio of 3 parts by weight of Ketjen black and 92 parts by weight of manganese dioxide (manufactured by Tosoh Corporation), and then 20 parts by weight of water was added at a weight ratio of solids. And mixed for 5 minutes. As a binder, a dispersion of polytetrafluoroethylene (D-1: manufactured by Daikin Industries, Ltd.) was added in a state where 5 parts by weight as a solid content was diluted in the remaining water, and mixed for 5 minutes. The water content in the compounding agent was adjusted to 25 to 30 with respect to 100 solids.

  (Sheet forming) Rolling the mixed compound using two rolls with a diameter of 250 mm, adjusting the roll temperature to 130 ± 5 ° C., press pressure of 7 tons / cm, roll interval of 0.4 mm, rotation speed of 10 rpm, and rolls. , Into sheets. The compounding agent (preliminary sheet) passed through the roll was dried at 105 ° C. ± 5 ° C. until the residual moisture became 1% or less. Next, the dried preliminary sheet was pulverized using a pulverizer. Here, the pressed spare sheet was pulverized with a coffee mill until it reached at least twice the original apparent volume. Most of the pulverized particle diameter was 1 mm or less, and the polytetrafluoroethylene fiber added as a binder was also cut to a length of 1 mm or less.

The pulverized material was again rolled into a sheet. The roll interval was adjusted to 0.6 ± 0.05 mm, the roll temperature was set to 120 ± 10 ° C., the press pressure was set to 7 ton / cm, and the rotation speed was set to 10 rpm to obtain a sheet-like mixture layer. The sheet mixture layer had a thickness of 1.0 mm, a density of 2.5 g / cm ³ , and a porosity of 42%. The thickness of the sheet-shaped mixture layer of 1.0 mm corresponds to 5.9% of the inner diameter of the battery assembled as described later.

As described above, two sheet-shaped mixture layers 20 and 21 for the inner periphery and the outer periphery (see FIGS. 1 and 3C) were produced. The sheet-shaped mixture layer 20 for the inner periphery was cut into a width of 37 mm and a length of 51 mm. The outer peripheral sheet-shaped mixture layer 21 was cut into a width of 37 mm and a length of 61 mm. At this time, the positive electrode area defined by the sheet-like mixture layer 20.21 is 3.7 × 5.1 + 3.7 × 6.1 = 41.44 cm ² .

(Current Collector) An expanded metal made of stainless steel 316 and having a thickness of 0.2 mm was used as the current collector 22. The expanded metal was cut into a width of 34 mm and a length of 56 mm, and a positive electrode lead 15 made of a stainless steel ribbon having a thickness of 0.3 mm and a width of 3 mm was attached by resistance welding to the center in the length direction. After a carbon paste (manufactured by Nippon Graphite Co., Ltd.) was applied to the current collector 22 to such an extent that the mesh was not broken, it was dried at a heating temperature of 105 ° C. ± 5 ° C. for 2 hours or more. Here, the carbon paste was applied so as to be 4 mg / cm ² .

  Next, as shown in FIG. 4 (c), the two sheet-shaped mixture layers 20 and 21 are fixed with only one end in the length direction with the current collector 22 interposed therebetween. Was integrated. More specifically, the two sheet-shaped mixture layers 20 and 21 for the inner and outer circumferences are aligned at one end in the length direction, and the ends of the current collector 22 are connected to the ends of the sheet-shaped mixture layers 20 and 21. It was set so as to be 1 mm inward from the part, and was set so as not to protrude also in the width direction. In this state, 5 mm was pressed from an end in the length direction by a press to integrate the three members. Subsequently, the sheet-shaped mixture layers 20 and 21 and the current collector 22 were dried with hot air at 250 ° C. ± 10 ° C. for 6 hours to obtain a positive electrode 3. Here, the integration of the sheet-shaped mixture layers 20 and 21 and the current collector 22 is a problem in operation, and the independent sheet-shaped mixture layers 20 and 21 and the current collector 22 may be combined. However, there is no problem in characteristics even when integrated at the time of winding.

<Negative electrode manufacturing method>
The negative electrode 4 was obtained by cutting a lithium foil having a width of 37 mm and a thickness of 0.3 mm into 46 mm and 96 mm, and excluding 10 mm from one end of the short side foil 4a, 36 mm was overlapped with the long side foil 4b and pressed. The negative electrode lead body 16 was formed by embossing one end of a nickel ribbon having a thickness of 0.1 mm and a width of 3 mm, and was fixed by being pressed between two foils.

<Assembly method>
A separator made of a microporous polyethylene film having a width of 44 mm and a thickness of 0.025 mm (Hypore manufactured by Asahi Kasei Corporation) is cut into 220 mm and sandwiched between two cores 25 each having a diameter of 4 mm as shown in FIG. I wrapped one lap. Next, as shown in FIGS. 4B and 4C, the lithium metal foil of the negative electrode 4 having a single length of 10 mm is wound around the winding core 25 with the one-side length of 10 mm, and is wound around the separator 5 one time. The side on which the agent layers 20 and 21 were fixed was placed on the winding core 25 side and wound. After the completion of the winding, the separator 5 covered the outermost periphery, and the winding end portion of the separator 5 was fixed with a fixing tape. The separator 5 related to the winding end portion E was bent so that the sheet-shaped mixture layers 20 and 21 were covered with the separator 5. Thus, a wound body 6 having a number of turns of about 2 was obtained.

  A 0.2 mm thick polypropylene insulating plate is inserted into the bottom of the outer can 2 made of a nickel-plated iron can, and the wound body 6 is placed thereon with the positive and negative lead members 15 and 16 facing upward. Inserted. The negative electrode lead body 16 was resistance-welded to the upper inner surface of the outer can 2. The positive electrode lead body 15 was resistance-welded to the lower surface of the terminal body 10 after the insulating plate 11 was inserted. At this time, the insulation resistance was measured, and it was confirmed that there was no short circuit.

As the electrolytic solution, 3.3 ± 0.1 ml of 0.5 M LiClO ₄ / (PC + DME = 1: 2) was injected into the outer can 2. The injection was divided into three times, and the whole amount was injected under reduced pressure in the final step. After the injection of the electrolyte, the lid 8 was fitted and sealed by laser welding. Thus, a nonaqueous electrolyte battery according to Example 1 was obtained.

(Post-treatment: pre-discharge, aging)
The sealed battery was pre-discharged at a resistance of 1Ω for 30 seconds, stored at 45 ° C. for 24 hours, and then subjected to a secondary pre-discharge at a constant current of 1 A for 3 minutes. The battery after the preliminary discharge was aged at room temperature for 7 days.

The inner-side sheet-shaped mixture layer 20 has a thickness of 1.6 mm, a width of 37 mm, and a length of 33 mm, and the outer-side sheet-shaped mixture layer 21 has a thickness of 1.6 mm, a width of 37 mm, and a length of 43 mm. The positive electrode 3 was manufactured with an expanded metal as the current collector 22 interposed between the two sheet-shaped mixture layers 20 and 21 having a width of 34 mm and a length of 37 mm. The dimensions of the negative electrode 4b were 0.5 mm thick, 37 mm wide and 80 mm long, and the separator made of a microporous polyethylene film was 44 mm wide, 0.025 mm thick and 150 mm long. Except for these, in the same manner as in Example 1, a lithium-manganese dioxide battery according to Example 2 was obtained. The number of turns of the wound body 6 was approximately 1.5 turns, and the thickness of the sheet-shaped mixture layer of 1.6 mm was equivalent to 9.4% of the inner diameter of the assembled battery. At this time, the area of the positive electrode defined by the sheet mixture layer is 3.7 × 3.3 + 3.7 × 4.3 = 28.12 cm ² .

The inner-side sheet-shaped mixture layer 20 has a thickness of 0.7 mm, a width of 37 mm, and a length of 73 mm, and the outer-side sheet-shaped mixture layer 21 has a thickness of 0.7 mm, a width of 37 mm, and a length of 83 mm. The positive electrode 3 was manufactured with an expanded metal as the current collector 22 interposed between the two sheet-shaped mixture layers 20 and 21 having a width of 34 mm and a length of 78 mm. The dimensions of the negative electrode 4b were 0.5 mm thick, 37 mm wide and 80 mm long, and the separator made of a microporous polyethylene film was 44 mm wide, 0.025 mm thick and 300 mm long. Except for these, in the same manner as in Example 1, a lithium-manganese dioxide battery according to Example 3 was obtained. The number of turns of the wound body 6 was approximately three times, and the thickness of the sheet-shaped mixture layer of 0.7 mm was equivalent to 4.1% of the inner diameter of the assembled battery. At this time, the positive electrode area defined by the sheet-shaped mixture layers 20 and 21 is 3.7 × 7.3 + 3.7 × 8.3 = 57.72 cm ² .

The positive electrode 3 was produced in the same manner as in Example 1 except that the density of the sheet-shaped mixture layers 20 and 21 was changed to 2.8 g / cm ³ and the porosity was changed to 35%. Using this positive electrode 3, a lithium-manganese dioxide battery was produced in the same manner as in Example 1.

The positive electrode 3 was produced in the same manner as in Example 1 except that the density of the sheet-shaped mixture layers 20 and 21 was changed to 2.16 g / cm ³ and the porosity was changed to 50%. Using this positive electrode 3, a lithium-manganese dioxide battery was produced in the same manner as in Example 1.

  The positive electrode 3 was produced in the same manner as in Example 1 except that a stainless steel plain-woven wire mesh having a thickness of 0.2 mm, a width of 34 mm, and a length of 56 mm was used as the current collector 22. Using this positive electrode 3, a lithium-manganese dioxide battery was produced in the same manner as in Example 1.

The positive electrode 3 was produced in the same manner as in Example 1 except that the density of the sheet-shaped mixture layers 20 and 21 was changed to 3.0 g / cm ³ and the porosity was changed to 30%. Using this positive electrode 3, a lithium-manganese dioxide battery was produced in the same manner as in Example 1.

A lithium-manganese dioxide battery was obtained in the same manner as in Example 1, except that 0.5 M LiCF ₃ SO ₃ / (PC + DME = 1: 2) was used as the electrolytic solution.

The positive electrode 3 was produced in the same manner as in Example 1 except that the width of the current collector 22 was set to 37 mm, which was the same as the width of the sheet-shaped mixture layers 20 and 21. Using this positive electrode 3, a lithium-manganese dioxide battery was produced in the same manner as in Example 1. At this time, both upper and lower ends of the current collector 22 were exposed from the sheet mixture layers 20 and 21.
<< Comparative Example 1 >>

The positive electrode 3 was produced in the same manner as in Example 1 except that the length of each of the sheet-shaped mixture layers 20 and 21 and the current collector 22 was changed to 56 mm, and that the entire electrode was subjected to press-compression treatment. . In addition, winding was performed using this positive electrode 3 in the same manner as in Example 1, but the mixture layer was peeled off, and a wound body could not be produced. Therefore, a battery could not be manufactured.
<< Comparative Example 2 >>

The inner peripheral sheet-shaped mixture layer 20 has a thickness of 0.28 mm, a width of 37 mm, and a length of 150 mm, and the outer peripheral sheet-shaped mixture layer 21 has a thickness of 0.28 mm, a width of 37 mm, and a length of 150 mm. The expanded metal as the current collector 22 interposed between the two sheet-shaped mixture layers 20 and 21 was 34 mm in width and 148 mm in length, and was subjected to press-bonding treatment over the entire electrode as in Comparative Example 1. Except for the above, a cathode was produced in the same manner as in Example 1. The dimensions of the negative electrode 4b were 0.2 mm in thickness, 37 mm in width, and 184 mm in length. The separator made of a microporous polyethylene film was 44 mm in width, 0.025 mm in thickness, and 600 mm in length. At this time, the area of the positive electrode defined by the sheet mixture layer is 3.7 × 22.4 + 3.7 × 22.4 = 165.76 cm ² . The number of turns of the wound body 6 was approximately 6 turns, and the thickness of the sheet-shaped mixture layer: 0.28 mm was equivalent to 1.6% of the inner diameter of the assembled battery.
<< Comparative Example 3 >>

By forming a positive electrode mixture into a hollow cylindrical shape having an outer diameter of 17 mm, an inner diameter of 11 mm and a height of 37 mm, and disposing lithium as a negative electrode inside the positive electrode mixture through a separator, a bobbin type lithium-manganese dioxide battery is obtained. Produced. At this time, the facing electrode area of the positive electrode and the negative electrode was about 13 cm ² .

  Prior to the evaluation of the characteristics of the lithium-manganese dioxide batteries according to Examples 1 to 9 and Comparative Examples 1 to 3, the following tests were performed.

The positive and negative electrodes 3 and 4 were short-circuited to the wound body 6 according to Example 1 as shown in FIGS. That is, as shown in FIG. 5A, a hole 30 of 0.25 cm ² is directly formed in the separator 5 so that the surface of the sheet-shaped mixture layer 21 and the negative electrode 4 come into contact with each other. As shown in FIG. 5B, a short circuit path is provided between the surface of the sheet-shaped mixture layer 21 and the negative electrode 4 with a stainless steel wire 31 having a diameter of 0.065 mm, and as shown in FIG. The above three types of wound bodies 6 were prepared in which a short circuit path was provided between the current collector 22 and the negative electrode 4 with a stainless steel wire 31 of φ0.065 mm. Each of the wound bodies 6 was loaded into the outer can 2 to produce three types of nonaqueous electrolyte batteries (a), (b), and (c).

The temperature rise when the electrolyte (0.5 M LiClO ₄ / (PC + DME = 1: 2)) was injected into the three types of lithium-manganese dioxide batteries (a) to (c) was measured. Table 1 shows the results.

  As shown in Table 1, only in the case of the model (c), the temperature rose rapidly and exceeded 110 ° C. When the battery after the test is further disassembled, in the batteries of the models (a) and (b), no abnormality is seen in the separator 5 and the like, but in the model (c), the stainless wire 31 used for the short-circuit path disappears. After that, the separator 5 in the vicinity thereof was darkened.

  From this result, it can be seen that abnormal heat generation occurs only when a short-circuit path is formed between the current collector 22 of the positive electrode 3 and the negative electrode 4 as a short-circuit site inside the battery. Based on this, safety at the time of overdischarge is determined based on whether or not lithium is deposited on the current collector 22 of the positive electrode 3.

  After the batteries of Example 1 and Comparative Example 9 were completely discharged, the voltage between the terminals of the batteries was forcibly discharged to -3 V for 1 hour, and then whether or not lithium was deposited on the current collector 22 was observed. Table 2 shows the results.

As shown in Table 2, Example 1 in which the current collector 22 was not exposed and LiClO ₄ was employed as the high-conductivity electrolytic solution, and in which the current collector 22 was not exposed and LiCF ₃ SO was used as the electrolytic solution, _{In the} battery according to Example 8 employing No. ₃ , no direct deposition of lithium on the current collector 22 was observed. On the other hand, in the battery according to the ninth embodiment in which the current collectors 22 at both upper and lower ends of the wound body 6 are exposed and the electrolytic solution having a high conductivity is used, lithium is collected on the current collector 22. Precipitation was observed. As described above, when the entire inner and outer surfaces of the current collector 22 are covered with the sheet-shaped mixture layers 20 and 21, when an electrolyte having high conductivity is used, such as an electrolyte using lithium perchlorate as a solute. However, it was confirmed that the precipitation of dendritic lithium during overdischarge can be reliably suppressed.

  Table 3 shows the results obtained by discharging the batteries of Example 1 and Example 8 at a load of 300 mA, and measuring the discharge capacity until the battery voltage reached 2.0 V.

As shown in Table 3, in the battery according to Example 8 using LiCF ₃ SO ₃ as the solute of the electrolyte, the battery according to Example 1 in which LiClO ₄ was used as the solute of the electrolyte was used. Due to the low conductivity, the discharge capacity was reduced.

  With respect to 100 lithium-manganese dioxide batteries of each of Examples 1 to 8 and Comparative Examples 1 to 3, the failure rate and the short circuit occurrence rate during battery assembly were examined. Moreover, about each said lithium-manganese dioxide battery, it discharged at 20 degreeC and 5 mA to 2.0 V, and measured discharge capacity. Using another battery, the battery was discharged to 2.0 V at 100 mA, the discharge capacity was measured, and the characteristics at a medium load were examined. These results were as shown in Table 4.

As is clear from the results in Table 4, in Example 1, there was no trouble during assembly and no short circuit occurred. In Example 2, a good battery was obtained without cracks or short circuits even when a thicker sheet-like mixture layer was used. In Example 3, although the capacity was somewhat reduced due to the length of the electrode, the characteristics under a medium load were improved. In Examples 4 and 5, by setting the porosity of the sheet-shaped mixture layer to 35 to 50%, no deterioration in characteristics under a medium load was observed, and no cracks or short paths occurred during winding. In Example 6, even if the current collector was changed, a good result which was not different from the above was obtained. In Example 7, since the porosity of the sheet-shaped mixture layer was lower than the preferred range, the discharge capacity at 5 mA was increased as compared with Example 1, but winding was somewhat difficult, and a slight Failure occurred. In Example 8, since LiCF ₃ SO ₃ was used as the solute of the electrolytic solution, the discharge of 100 mAh was slightly lower than that of the battery according to Example 1 in which LiClO ₄ was used as the solute of the electrolytic solution. In Example 9, the width of the current collector and the sheet-shaped mixture layer were the same, and the current collector slightly exposed to the edge of the sheet-shaped mixture layer due to variations in winding. Occurrence of short circuit was observed.

On the other hand, in Comparative Example 1 in which the sheet-shaped mixture layer having the same thickness as in Example 1 was completely fixed to the current collector to form a positive electrode, a wound body could not be produced. In Comparative Example 2 similar to the conventional wound type battery using the long positive electrode in which the thin mixture layer was integrated with the current collector, the reaction area was large, and the decrease in capacity under a medium load was small. However, the amount of the active material to be filled was limited, so that the capacity of the battery was small. In addition, since it is long, it is easy to cause winding deviation in the width direction at the time of winding, and occurrence of short circuit was also recognized. Further, in Comparative Example 3 having a bobbin-type structure, although the capacity of the battery itself was large, the capacity was significantly reduced at a medium load, and the battery was usable only at a low load.

  As described above, in Examples 1 to 9 of the present invention, the capacity of the wound-type battery is larger than that of the conventional wound-type comparative example 2, and the wound-type battery more suitable for use under a medium load than the bobbin-type comparative example 3. Could be configured. Further, in the batteries of Examples 1 to 8 in which the end of the current collector was not exposed from the end of the sheet-shaped mixture layer, no short circuit occurred, and the porosity of the mixture layer was 35 to 50%. In the batteries of Examples 1 to 6 and Example 8 described above, occurrence of defects such as peeling of the mixture layer and generation of cracks at the time of winding was not observed. In Example 8 using lithium perchlorate as the electrolyte, the load characteristics could be further improved. As is apparent from the above description, the present invention makes it possible to easily assemble a battery having a large capacity and suitable for use under a medium load.

1 is a cross-sectional plan view of a nonaqueous electrolyte battery according to a first embodiment of the present invention. It is a vertical front view of the nonaqueous electrolyte battery of the present invention. It is a figure showing the state before winding of the electrode (positive electrode) of the layered structure of the present invention. It is a figure for explaining a manufacturing method of a roll. (A), (b), (c) is a figure which shows the state of the positive and negative electrodes of the wound body which concerns on the test model for verifying the safety in an overdischarge state.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte battery 2 Outer can 3 Positive electrode 4 Negative electrode 5 Separator 6 Winding body 20 Sheet-shaped mixture layer located on the inner peripheral side 21 Sheet-shaped mixture layer located on the outer peripheral side 22 Current collector S Positive electrode winding Start end E Winding end of positive electrode

Claims (16)

  An electrode having a laminated structure in which a sheet-shaped mixture layer is disposed on both sides of the current collector without being substantially fixed to the current collector, a counter electrode of the electrode, and a separator interposed therebetween are swirled. A battery characterized in that a wound body wound in a shape is housed in a battery container.   The battery according to claim 1, wherein in the electrode having a laminated structure, the current collector is a plain woven wire mesh, a metal foil, an expanded metal, a lath mesh, or a punching metal.   3. The battery according to claim 1, wherein in the electrode having a laminated structure, the sheet-shaped mixture layer only at the end on the winding center side is fixed to the current collector. 4.   The battery according to any one of claims 1 to 3, wherein in the electrode having a laminated structure, an end of the current collector is located so as not to be exposed from an end of the sheet-shaped mixture layer.   The battery according to any one of claims 1 to 4, wherein in the electrode having a laminated structure, the width of the current collector is smaller than the width of the sheet-shaped mixture layer.   The battery according to any one of claims 1 to 5, wherein in the electrode having a laminated structure, the porosity of the sheet mixture layer is 35 to 50%.   The battery according to any one of claims 1 to 6, wherein in the electrode having a laminated structure, the sheet-shaped mixture layer has a thickness corresponding to 4 to 10% of the battery inner diameter.   In the electrode having a laminated structure, the length of the sheet-shaped mixture layer located inside the current collector before winding is shorter than the length of the current collector, and the length of the sheet-shaped mixture layer located outside the current collector is reduced. The battery according to any one of claims 1 to 7, wherein a length of the battery before rotation is longer than a length of the current collector.   An electrode having a laminated structure, wherein the current collector has a wound body in which the entire inner and outer surfaces are covered with a sheet-shaped mixture layer, and a non-aqueous electrolyte containing lithium perchlorate as a solute is used. 9. The battery according to any one of 8 above.   The battery according to any one of claims 1 to 9, wherein the number of turns of the wound body is more than one turn and not more than 3 turns.   The battery according to claim 1, wherein the counter electrode is a metal or a metal alloy.   The battery according to claim 11, wherein the counter electrode is lithium or a lithium alloy.   The electrode having a laminated structure in which sheet-shaped mixture layers are disposed on both sides of the current collector, while causing a displacement in the winding direction between the current collector and the sheet-shaped mixture layer, With a counter electrode and a separator interposed therebetween to form a wound body, which is housed in a battery container.   A step of arranging a sheet-shaped mixture layer on both sides of the current collector in a state not being substantially fixed to the current collector to form an electrode of a laminated structure, the electrode of the laminated structure and its counter electrode and interposed therebetween. Separator, a step of winding while causing a displacement in the winding direction between the current collector of the electrode of the laminated structure and the sheet-shaped mixture layer, and the wound body obtained by the winding step 14. The method for manufacturing a battery according to claim 13, further comprising a step of housing the battery in a battery container.   The method for producing a battery according to claim 13 or 14, wherein the sheet-shaped mixture layer only at the end on the winding center side of the electrode having a laminated structure is fixed to the current collector. 16. An electrode having a laminated structure in which a sheet-like mixture layer shorter than the length of the current collector and a sheet-like mixture layer longer than the length of the current collector are arranged on both sides of the current collector. The method for producing a battery according to any one of the above.

Images