JP2006260904A - Winding type battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a winding type battery which can improve the volumetric efficiency of the battery and can reduce a manufacturing cost. <P>SOLUTION: In the winding type battery 10, a beltlike anode 1 where anode active substance layers are formed in both sides of a collector, and a beltlike cathode 5 where cathode active substance layers are formed in both sides of the collector, are wound so that the one end of the separator 3 by the side of an inner periphery and the one end of the positive electrode 1 from the almost same position through the separator 3, namely, the structure that the part of the unnecessary separator taken out from the electrode is not wound does not exist and simplified conventionally is taken. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wound battery in which a positive electrode and a negative electrode are wound through a separator, and a method for manufacturing the same.

  In recent years, electronic devices such as mobile phone devices and portable game devices have been reduced in size and performance, and accordingly, there has been a demand for higher energy density and higher capacity of batteries used as power sources. Lithium ion secondary batteries are particularly promising because they provide a higher energy density than lead batteries and nickel cadmium (Ni-Cd) batteries, which are conventional aqueous electrolyte secondary batteries.

  Lithium-ion secondary batteries can be made in various shapes such as cylindrical and square, and each has a positive electrode member formed in a strip shape, and a negative electrode member and a separator alternately stacked. It is produced by a so-called winding method in which the laminated electrode body is wound around a winding core.

  FIG. 9 is a schematic diagram showing the structure of a conventional wound battery. As shown in FIG. 9, the wound battery 110 includes a strip-like positive electrode 101 in which a positive electrode active material layer is formed on both sides of a current collector, and a negative electrode active material layer on both sides of the current collector. A strip-shaped negative electrode 105 is wound many times through a separator 103. Gel electrolyte layers 102 are formed on both surfaces of the positive electrode 101. Gel electrolyte layers 104 are formed on both surfaces of the negative electrode 105. A positive electrode tab 106 is bonded to one end of the positive electrode 101, and a negative electrode tab 107 is bonded to one end of the negative electrode 105.

  In FIG. 9, reference numerals 108a to 108f are insulating coatings (hereinafter referred to as protective tapes as appropriate). In order to reduce the occurrence of an internal short circuit of the battery, a protective tape 108a covering the positive electrode tab 106 joined to the end of the positive electrode 101 is attached, and the protective tape 108b and the protective tape cover the negative electrode 105 of the opposite portion. 108f is attached. Further, a protective tape 108c that covers a portion exposed from the gel electrolyte layer 104 at the end of the negative electrode 105 is attached, and a protective tape 108d and a protective tape 108e are attached so as to cover the positive electrode 101 of the opposite portion.

  FIG. 10 is a partially enlarged cross-sectional view showing a state in which the positive electrode and the negative electrode of a conventional wound battery are extended. As shown in FIG. 10, the negative electrode 111 is formed by laminating a negative electrode active material layer 114 on both surfaces of a negative electrode current collector 115. In order to prevent the occurrence of an internal short circuit, a separator 113 for separating the negative electrode 111 and the positive electrode 112 is provided.

  As shown in FIG. 10, the positive electrode 112 is formed by laminating a positive electrode active material layer 117 on both surfaces of a positive electrode current collector 116. A positive electrode tab 119 is joined to one end of the positive electrode current collector 116 by, for example, spot welding. Since the positive electrode tab 119 has a thickness and may cause an internal short circuit in particular, it is covered with the protective tape 120.

  FIG. 11 is a diagram for explaining a conventional method of manufacturing a wound battery. As shown in FIG. 11, the winding device includes an original fabric R121, and a positive electrode 121, a separator S121, a negative electrode 122, and a separator S122 that are derived from the original fabric R121. A positive electrode 121, a separator S121, a negative electrode 122, and a separator S122 are wound around the original fabric R121. In the case of a gel electrolyte battery, for example, a battery in which a positive electrode and a negative electrode on which a gel electrolyte has been applied is wound is used.

  In the wound battery 110, the separator S121 and the separator S122 derived from the raw fabric R121 are wound around the core 123 in advance, for example, the positive electrode 121 and the negative electrode 122 are inserted, and then wound around the core 123 a predetermined number of times. Produced. Patent Document 1 below describes a conventional method for manufacturing a wound battery.

Japanese Patent Laid-Open No. 10-321220

  The separator S121 and the separator S122 that are wound around the winding core 123 in advance are denoted by La and Lb in FIG. La and Lb are portions extended from the negative electrode active material layer 114 and are portions that do not need to function as separators.

  As described above, the conventional wound type battery has an unnecessary separator, and thus the volume efficiency of the battery is lowered. Further, the separator is very expensive, and conventionally, since the separators La and Lb which are unnecessary are arranged in this way, the manufacturing cost of the battery is high.

  Accordingly, an object of the present invention is to provide a wound battery that can improve the volumetric efficiency of the battery and reduce the manufacturing cost, and a method for manufacturing the same.

In order to solve the above-described problems, the present invention provides:
A positive electrode in which a positive electrode active material layer is formed on both sides of a strip-shaped current collector;
A negative electrode in which a negative electrode active material layer is formed on both sides of a strip-shaped current collector;
An electrolyte and a separator interposed between the positive electrode and the negative electrode,
A wound battery in which a positive electrode and a negative electrode are wound via a separator,
One end of a separator and one end of a positive electrode on the inner peripheral side of the winding type battery, or one end of a separator and one end of a negative electrode are wound from substantially the same position.

This invention
Form a gel electrolyte layer on both sides of the positive and negative electrodes,
A method for producing a wound battery comprising placing a separator on at least one gel electrolyte layer of a positive electrode and a negative electrode and winding the separator.

  According to this invention, one end of the separator on the inner peripheral side of the wound battery and one end of the positive electrode, or one end of the separator and one end of the negative electrode are wound from substantially the same position. Since it is a wound battery, the volumetric efficiency of the battery can be improved and the manufacturing cost can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view schematically showing a wound battery according to an embodiment of the present invention. This wound battery represents a wound battery in which the electrolyte is a gel electrolyte. As shown in FIG. 1, in the wound battery 10, a negative electrode 41 and a positive electrode 42 are stacked via a separator 43 and wound.

  The wound battery 10 is covered and sealed with an exterior film made of an insulating material. Gel electrolyte layers 46 are formed on both surfaces of the negative electrode 41 and the positive electrode 42. On the gel electrolyte layers 46 on both sides of the positive electrode 42, a separator 43 is placed and stacked. The tab 45 is joined to one end of each of the strip-like negative electrode 41 and the positive electrode 42.

  The tab 45 is joined by spot welding, for example. The joining of the tab 45 is not limited after winding, and may be performed before winding. The tab 45 is sandwiched between sealing portions that are peripheral portions of an exterior film (not shown). Moreover, the resin film is distribute | arranged to the part which the tab 45 contacts an exterior film.

  FIG. 2 is a schematic diagram showing the structure of a wound battery according to an embodiment of the present invention. As shown in FIG. 2, the wound battery 10 includes a large number of positive electrodes 1 and negative electrodes 5 through the separator 3 so that one end of the inner separator 3 and one end of the positive electrode 1 are substantially in the same position. It is wound several times. Note that one end of the inner peripheral side separator 3 and one end of the positive electrode 1 are in substantially the same position, that one end of the inner peripheral side separator 3 is positioned between one end of the positive electrode active material layer and one end of the positive electrode. That means.

  The positive electrode 1 includes, for example, a positive electrode current collector having a band shape and a positive electrode active material layer formed on both surfaces of the positive electrode current collector. The lengths of the positive electrode active material layers provided on both surfaces of the positive electrode current collector are different. Specifically, in order to improve volumetric efficiency, a portion where the positive electrode active material layer is not provided on the outermost periphery of the positive electrode 1 and one side of the positive electrode current collector is exposed (hereinafter referred to as a single side exposed portion). In contrast, a positive electrode active material layer is provided on both sides of the inner periphery of the positive electrode 1. A gel electrolyte layer 2 is formed on the positive electrode active material layer. Further, the inner peripheral side and the outer peripheral end of the positive electrode 1 are provided with portions where the positive electrode current collector is exposed without being covered with the positive electrode active material layer (hereinafter referred to as a positive electrode current collector exposed portion). .

  A positive electrode tab 6 is welded to the exposed portion of the positive electrode current collector on the inner peripheral side. Then, one end of the positive electrode current collector exposed portion on the inner peripheral side is covered with a protective tape 8 a so as to cover the positive electrode tab 6. By providing the protective tape 8a in this way, contact between the positive electrode 1 and the negative electrode 5 can be avoided, and the occurrence of an internal short circuit can be prevented.

  The separators 3 arranged on both sides of the positive electrode are composed of first and second separators, and are defined according to the lengths of the positive electrode active material layers having different lengths provided on both surfaces of the positive electrode current collector. The lengths of the first separator and the second separator are different. Specifically, for example, it is selected to be approximately the same as the length of the positive electrode active material layer provided on both surfaces of the positive electrode current collector. Here, of the two separators, the one closer to the center of the wound battery 10 is referred to as a first separator, and the one far from the center is referred to as a second separator. Thus, by using two separators and selecting the lengths so as to differ according to the length of the positive electrode active material layer, the amount of separator used can be minimized. The first separator faces the single-sided exposed portion on the outermost periphery of the positive electrode 1 and is longer than the second separator.

  The negative electrode 5 includes, for example, a negative electrode current collector having a band shape and a negative electrode active material layer formed on both surfaces of the negative electrode current collector. The lengths of the negative electrode active material layers provided on both surfaces of the negative electrode current collector are different. A gel electrolyte layer 4 is formed on the negative electrode active material layer. Further, the inner peripheral side and the outer peripheral end of the negative electrode 5 are provided with portions where the negative electrode current collector is exposed without being covered with the negative electrode active material layer (hereinafter referred to as negative electrode current collector exposed portion). . The negative electrode 5 is wound further from the inside than the positive electrode 1.

  A negative electrode tab 7 is welded to the negative electrode current collector exposed portion on the inner peripheral side. Then, the negative electrode current collector exposed portion on the inner peripheral side has protective tapes 8 b and 8 f at positions facing the one end of the positive electrode current collector exposed portion on the inner peripheral side and the positive electrode tab 6.

  The wound battery 10 does not have a portion of the separator that has been wound earlier than the electrode, and has a simplified structure. As a result, the volumetric efficiency of the battery can be improved.

(Positive electrode)
FIG. 3 is a partially enlarged cross-sectional view of a positive electrode according to an embodiment of the present invention. As shown in FIG. 3, the positive electrode 24 is formed on both surfaces of a positive electrode current collector 28 in which, for example, a positive electrode active material layer 27 is a metal stay such as an aluminum foil.

  A gel electrolyte layer 26 is formed on the positive electrode active material layer 27, and the separator 25 is placed on and overlaid on the gel electrolyte layer 26.

  A positive electrode tab 29 is welded to one end of the positive electrode current collector 28. The positive electrode tab 29 is covered with a protective tape 30. By covering the positive electrode tab 29 with the protective tape 30, the occurrence of an internal short circuit can be suppressed, and the yield can be improved.

  As shown in FIG. 3, it is preferable that the separator 25 is placed and stacked only on the gel electrolyte layer 26 formed on the positive electrode active material layer 27. Since the gel electrolyte layer 26 overlaps only on the positive electrode active material layer 27, the separator 25 can be suppressed to the minimum necessary. As a result, the manufacturing cost can be reduced and the volume efficiency of the battery can be improved. Capacity can be increased.

  When the separator 25 is placed on the gel electrolyte layer 26, the separator 25 absorbs the electrolytic solution and sticks to the gel electrolyte layer 26, so that the separator 25 can be easily stacked on the gel electrolyte layer 26. Further, when the separator 25 is attached to the gel electrolyte layer 26, the separator can be wound without winding.

The positive electrode active material layer 27 desirably contains a sufficient amount of Li. For example, a composite metal oxide composed of lithium and a transition metal represented by the general formula LiM _X O _Y (where M represents at least one of Co, Ni, Mn, Fe, Al, V, and Ti) or Li An intercalation compound containing can be suitably used.

(Negative electrode)
FIG. 4 is a partially enlarged cross-sectional view of a negative electrode according to an embodiment of the present invention. As shown in FIG. 4, in the negative electrode 21, the negative electrode active material layer 23 is laminated on both surfaces of the negative electrode current collector 22. A gel electrolyte layer is formed on the negative electrode active material layer 23. As the negative electrode current collector 22, for example, a metal foil such as a copper foil is used.

  As the negative electrode active material layer 23, any material can be used as long as it is a material that electrochemically doespe / dedoped lithium with a potential of lithium metal of 2.0 V or less. For example, non-graphitizable carbon, artificial graphite, natural graphite, pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphites, glassy carbons, organic polymer compound fired bodies (phenolic resins) Carbonaceous material such as carbon fiber, activated carbon, carbon black, etc., obtained by firing and carbonizing furan resin or the like at an appropriate temperature.

  A metal capable of forming an alloy with lithium and its alloy can also be used. For example, oxides such as iron oxide, ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide, and tin oxide that dope and dedoped lithium with a relatively low potential, and other nitrides can be used as well.

(Separator)
As the separator 25, for example, a polyolefin microporous film such as polyethylene or polypropylene is used.

(Electrolytes)
The gel electrolyte layer 26 is formed by gelling a nonaqueous electrolytic solution in which an electrolyte is dissolved in a nonaqueous solvent with a matrix polymer.

  As the non-aqueous electrolyte, a non-aqueous electrolyte obtained by dissolving an electrolyte salt in an organic solvent (non-aqueous solvent) can be used. The nonaqueous electrolytic solution is adjusted by appropriately combining an organic solvent and an electrolyte. Any organic solvent can be used as long as it is used for this type of battery. For example, propylene carbonate, ethylene carbonate, γ-butyrolactone, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4 Examples thereof include methyl 1,3 dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, acetate ester, butyrate ester, propionate ester and the like.

  As the matrix polymer, various polymers can be used as long as they absorb non-aqueous electrolyte and gel. For example, fluorine-based polymers such as poly (vinylidene fluoride) and poly (vinylidene fluoride-co-hexafluoropropylene), ether-based polymers such as poly (ethylene oxide) and cross-linked products thereof, and poly (acrylonitrile) ) Etc. can be used. As the matrix polymer, it is desirable to use a fluorine-based polymer particularly from the viewpoint of redox stability. By containing an electrolyte salt, ionic conductivity is imparted.

Any electrolyte salt can be used as long as it is used in this type of battery. For example, LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiCl, LiBr, LiN (CF ₃ SO ₂ ) _2, etc. Can be mentioned.

  As the solid electrolyte, any inorganic solid electrolyte or polymer solid electrolyte can be used as long as the material has lithium ion conductivity. Examples of the inorganic solid electrolyte include lithium nitride and lithium iodide. The polymer solid electrolyte is composed of an electrolyte salt and a polymer compound that dissolves the electrolyte salt. As the polymer compound, an ether-based polymer such as poly (ethylene oxide) or a crosslinked product thereof, a poly (methacrylate) ester-based compound, an acrylate-based compound, or the like can be used alone or in a molecule by being copolymerized or mixed.

  In this embodiment, a wound battery including a gel electrolyte as an electrolyte will be described. However, the present invention is not limited to this embodiment. For example, the present invention can be applied to a wound battery including an electrolytic solution as an electrolyte.

  FIG. 5 is a partially enlarged cross-sectional view of the positive electrode of the liquid battery. As shown in FIG. 5, the positive electrode 24 does not have the gel electrolyte layer 26. The positive electrode active material layer 27 is laminated on both surfaces of the positive electrode current collector 28. A separator 25 is stacked on the positive electrode active material layer 27. A positive electrode tab 29 is welded to one end of the positive electrode current collector 28.

Examples of a method for stacking the separator 25 on the positive electrode active material layer 27 include a method in which the separator 25 is previously moistened with an electrolytic solution and the like and placed on the positive electrode active material layer 27 to be stacked. An example is a method in which a separator is stacked on the positive electrode active material upper layer 27 with an adhesive. As the adhesive, for example, a known adhesive can be used.

In the positive electrode 24 shown in FIG. 5, since the separator 25 is stacked so as to cover only the positive electrode active material layer 27, there is no preceding winding portion of the separator extended from the positive electrode 24, and the winding type The battery 10 has a more simplified structure than before and can improve the volumetric efficiency of the battery.

  FIG. 6 is a partially enlarged cross-sectional view of the negative electrode of the liquid battery. As shown in FIG. 6, the negative electrode 21 according to the present invention has a negative electrode active material layer 23 formed on both surfaces of a negative electrode current collector 22. A negative electrode tab 31 is welded to one end of the negative electrode current collector 22.

(Production method)
FIG. 7 is a diagram for explaining an example of a method for manufacturing a wound battery according to an embodiment of the present invention. As shown in FIG. 7, for example, the winding device includes an original fabric R1 from which the negative electrode 41 is derived, an original fabric R1 from which the positive electrode 42 is derived, and a winding core 44.

  In the gel electrolyte battery, for example, by applying in advance, an electrode in which the gel electrolyte layer 46 is formed on both surfaces is wound around the raw fabric R1. As a coating method, a known method can be used. A separator 43 is placed on the gel electrolyte layer 46. When the separator 43 is placed on the gel electrolyte layer 46, the separator 43 is in a wet state and can be easily stacked on the gel electrolyte layer 46.

  The application of the gel electrolyte 46 and the stacking of the separator 43 are not limited to before forming the original fabric R1, and may be performed after forming the original fabric R1. A negative electrode 41 derived from the raw fabric R1 and a positive electrode 42 are wound around a core 44, and then wound a predetermined number of times, thereby producing a wound battery.

  In the method of manufacturing the wound battery shown in FIG. 7, since the separator 43 is preliminarily overlapped with the electrode and wound, the number of raw fabrics R1 that conventionally required four can be reduced to two. Therefore, the configuration of the winding device can be further simplified.

  Next, another embodiment of the present invention will be described. FIG. 8 is a schematic diagram showing the structure of a wound battery 10 according to another embodiment of the present invention. In the wound battery 10 according to another embodiment of the present invention, as shown in FIG. 8, the separator 3 is wound from a position near the positive electrode 1 so as to cover one end of the positive electrode 1 from both sides. A portion indicated by reference numeral 11 indicates a portion that is extended as compared with the separator of the above-described embodiment. The other configuration of the wound battery 10 is the same as that of the above-described embodiment, and thus the description thereof is omitted.

  In the wound battery 10 according to another embodiment of the present invention, the one end of the positive electrode 1 and the positive electrode tab 6 are protected by the protective tape 8 and the separator 3, so that repeated pressure is applied to the wound battery 10. Also in the case of occurrence, the occurrence of internal short circuit can be further suppressed. Therefore, an advantage that the durability can be further improved as compared with the above-described one embodiment can be obtained.

  Further, by extending the inner peripheral side separator 3 and stacking it on the positive electrode tab 6, the separator 3 and the positive electrode 1 can be simultaneously chucked at the beginning of winding, and as a result, the winding type battery 10 is manufactured. Is easy.

  Hereinafter, the present invention will be described by way of examples. Although compound names and numerical values are specifically exemplified and described, the present invention is not limited only to these examples.

<Example 1>
First, a negative electrode was produced as follows. To 100 parts by weight of coal-based coke serving as a filler, 30 parts by weight of coal tar-based pitch serving as a binder was added and mixed at about 100 ° C. Thereafter, it was compression molded by a press to obtain a precursor of a carbon molded body. Next, a pitch impregnation / firing step in which a carbon material molded body obtained by heat-treating this precursor at 1000 ° C. or less is further impregnated with a binder pitch melted at 200 ° C. or less and heat-treated at 1000 ° C. or less. Repeated several times. The carbon molded body was heat-treated at 2800 ° C. in an inert atmosphere to obtain a graphitized molded body, and then pulverized and classified to prepare a sample powder.

Here, X-ray diffraction measurement was performed on the obtained graphite material. As a result, the (002) plane spacing was 0.337 nm, and the (002) plane c-axis crystallite thickness was 50.0 nm. The true density by the pycnometer method is 2.23, the specific surface area by the BET method is 1.6 m ² / g, the particle size distribution by the laser diffraction method is an average particle size of 33.0 μm, a cumulative 10% particle size of 13.3 μm, The cumulative 50% particle size was 30.6 μm, the cumulative 90% particle size was 55.7 μm, the average fracture strength of the graphite particles was 7.1 kgf / mm ² , and the bulk density was 0.98 g / cm ³ .

  Then, 90 parts by weight of the mixed sample powder and 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder are mixed to prepare a negative electrode mixture, which is dispersed in N-methylpyrrolidone serving as a solvent, and a slurry (paste ).

  The negative electrode current collector is a strip of copper foil having a thickness of 10 μm. The negative electrode mixture slurry is applied to both sides of the current collector, dried, and then compression molded at a constant pressure to a size of 800 mm × 120 mm. The strip-shaped negative electrode was produced by cutting out into pieces.

  The negative electrode tab was prepared by cutting a metal net knitted with copper wires or nickel wires having a diameter of 50 μm at intervals of 75 μm. The negative electrode tab was spot welded to the negative electrode current collector uncoated portion to obtain a terminal for external connection.

The positive electrode was produced as described below. First, a positive electrode active material was prepared. 0.5 mol of lithium carbonate and 1 mol of cobalt carbonate were mixed, and this mixture was calcined in air at a temperature of 880 ° C. for 5 hours. As a result of X-ray diffraction measurement of the obtained material, it almost coincided with the LiCoO ₂ peak registered in the JCPDS file.

This LiCoO ₂ was pulverized into a powder having an average particle diameter of 8 μm. Then, 95 parts by weight of this LiCoO ₂ powder and 5 parts by weight of lithium carbonate powder are mixed, 91 parts by weight of this mixture, 6 parts by weight of flake graphite as a conductive agent, and 3 parts by weight of polyvinylidene fluoride as a binder. Were mixed to prepare a positive electrode mixture, which was dispersed in N-methylpyrrolidone to form a slurry (paste).

  As a positive electrode current collector, a strip-shaped aluminum foil having a thickness of 20 μm was used, and the positive electrode mixture slurry was uniformly applied to both sides of the current collector and dried, followed by compression molding at a constant pressure to be 640 mm × 118 mm. It cut out to the magnitude | size and produced the strip | belt-shaped positive electrode.

  The positive electrode tab was prepared by cutting a metal net knitted from aluminum wires having a diameter of 50 μm at intervals of 75 μm. The positive electrode tab was spot welded to the negative electrode current collector non-applied portion to obtain a terminal for external connection.

  A PVdF-based gel electrolyte was used as the electrolyte. First, a polymer (A) having a weight average molecular weight of 700,000 and a polymer (B) having a weight average molecular weight of 7% by weight of hexafluoropropylene copolymerized with vinylidene fluoride, A: B = 9 A matrix polymer mixed at a weight ratio of 1 was made. Then, a mixture of a matrix polymer, a non-aqueous electrolyte, and dimethyl carbonate (DMC), which is a polymer solvent, in a weight ratio of 1: 4: 8 is stirred and dissolved at 70 ° C. to obtain a sol electrolyte. did.

In the electrolytic solution, EC (ethylene carbonate): PC (propylene carbonate) as a nonaqueous solvent is mixed at a weight ratio of 60:40, and lithium hexafluorophosphate (LiPF ₆ ) is used as an electrolyte salt. It was used to prepare 0.8 mol / kg.

  Next, this sol-like electrolyte was applied using a bar coater, and the solvent was volatilized in a thermostatic bath at 70 degrees to form a gel electrolyte layer on the surfaces of the positive electrode and the negative electrode. And the separator was affixed on the formed gel electrolyte layer, and it was set as the structure where the separator overlapped only the gel electrolyte layer part. Thereafter, the positive electrode and the negative electrode are laminated and wound flat to produce a flat wound battery element, and this battery element is sealed in a laminate film under reduced pressure to obtain a thickness of 3.8 mm, a width of 35 mm, A gel electrolyte battery (Example 1) having a height of 62 mm was produced.

<Example 2>
A gel electrolyte battery (Example 2) having a thickness of 3.8 mm, a width of 35 mm, and a height of 62 mm was produced in the same manner as in Example 1 except that the separator on the inner periphery was overlaid on the negative electrode tab. did.

<Comparative Example 1>
In the same manner as in Example 1, a positive electrode, a negative electrode, and a separator were prepared, and when the negative electrode, the positive electrode, and the separator were wound, first, the metal core was used as the separator, and the separator was wound around 1.5 turns. After a half turn, the positive electrode was inserted and wound a predetermined number of times to produce a wound battery element, and this battery element was sealed in a laminate film under reduced pressure as in Example 1 to obtain a thickness of 3. A gel electrolyte battery (Comparative Example 1) having a size of 8 mm, a width of 35 mm, and a height of 62 mm was produced.

<Evaluation>
After measuring the battery capacity of Example 1, Example 2 and Comparative Example 1 and the reduction in the number and thickness of inner separators for Comparative Example 1 of Example 1 and Example 2, a table summarizing the measurement results was prepared. did. Table 1 below shows the number of inner peripheral separators reduced in Example 1, Example 2, and Comparative Example 1, the reduction in thickness, and the battery capacity.

  As shown in Table 1, Example 1 had 10 inner peripheral separators reduced compared to Comparative Example 1. In Example 1, a 20 μm separator was used, and the thickness was reduced by 200 μm. The battery capacity of Example 1 was 860 mAh.

  From the above, it was found that Example 1 can be filled with an active material in an amount corresponding to a thickness of 200 μm compared with Comparative Example 1, and as a result, the battery capacity of Comparative Example 1 can be increased by 60 mAh from 800 mAh.

  As shown in Table 1, in Example 2, unlike Example 1, separators overlapped on the tabs, and the number of inner peripheral separators was reduced by 8 compared to Comparative Example 1. In Example 2, a 20 μm separator was used, and the thickness could be reduced by 160 μm. Moreover, the battery capacity of Example 2 was 853 mAh.

  From the above, it was found that Example 2 can be filled with an amount of active material corresponding to a thickness of 160 μm as compared with Comparative Example 1, and as a result, the battery capacity of Comparative Example 1 can be increased by 53 mAh from 800 mAh.

  Moreover, in Example 2, since the overlapping part of the separator on the tab increased and an increased amount of separators was required, it was found that the increase in battery capacity was slightly less than in Example 1. However, since Example 2 can simultaneously chuck the separator and the positive electrode at the beginning of winding, it has been found that there is a merit that it is easy to manufacture.

  The present invention is not limited to the above-described embodiment of the present invention, and various modifications and applications are possible without departing from the spirit of the present invention. For example, not only the positive electrode but also a separator can be previously stacked on the negative electrode. The structure of the battery to which the present invention can be applied is not limited to the flat type, and can be applied to any structure within the scope of the present invention, such as a cylindrical shape and a rectangular shape.

1 is a perspective view schematically showing a wound battery of the present invention. It is the schematic diagram showing the structure of the winding type battery of this invention. It is a partial expanded sectional view of the positive electrode of this invention. It is a partial expanded sectional view of the negative electrode of this invention. It is a partially expanded sectional view of the other example of the positive electrode of this invention. It is a partially expanded sectional view of the other example of the negative electrode of this invention. It is a figure for demonstrating an example of the manufacturing method of the winding type battery of this invention. It is the schematic diagram showing the structure of the other example of the wound battery of this invention. It is the schematic diagram showing the structure of the conventional winding type battery. It is a partial expanded sectional view of the conventional positive electrode and negative electrode. It is a figure for demonstrating the manufacturing method of the conventional winding type battery.

Explanation of symbols

1, 24, 42 ... positive electrode 2, 4, 26, 46 ... gel electrolyte layer 3, 25, 43 ... separator 5, 21, 41 ... negative electrode 6, 29 ... positive electrode tab 7, DESCRIPTION OF SYMBOLS 31 ... Negative electrode tab 8, 30 ... Protective tape 10 ... Winding type battery 22 ... Negative electrode collector 23 ... Negative electrode active material layer 27 ... Positive electrode active material layer 28 ... Positive electrode current collector 44 ... Core 45 ... Tab

Claims (5)

A positive electrode in which a positive electrode active material layer is formed on both sides of a strip-shaped current collector;
A negative electrode in which a negative electrode active material layer is formed on both sides of a strip-shaped current collector;
An electrolyte and a separator interposed between the positive electrode and the negative electrode;
A wound battery in which the positive electrode and the negative electrode are wound through the separator,
One end of the separator and one end of the positive electrode on the inner peripheral side of the wound battery, or one end of the separator and one end of the negative electrode are wound from substantially the same position. Revolving battery. In claim 1,
The separator is composed of first and second separators,
Of the positive electrode and the negative electrode, the outermost electrode is different in the length of the active material layer formed on both surfaces of the electrode,
A wound battery characterized in that the lengths of the first and second separators are selected to be different depending on the length of the active material layer formed on both surfaces of the electrode. In claim 1,
The said positive electrode active material and the said negative electrode active material are active materials which can dope and dedope lithium ion, The winding type battery characterized by the above-mentioned. Form a gel electrolyte layer on both sides of the positive and negative electrodes,
A separator is placed on and wound on at least one of the positive electrode and the negative electrode on the gel electrolyte layer. In claim 4,
The positive electrode and the negative electrode are formed by laminating active materials on both sides of a strip-shaped current collector,
The said active material is an active material which can dope and dedope lithium ion, The manufacturing method of the winding type battery characterized by the above-mentioned.

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