JP2008192383A - Cylindrical non-aqueous electrolytic liquid primary cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical non-aqueous electrolytic liquid primary cell superior in load characteristics and large in capacity. <P>SOLUTION: This is a cylindrical non-aqueous electrolytic liquid primary cell having an electrode wound-around body winding a sheet-shape positive electrode and a sheet-shape negative electrode through a separator in a cylindrical outer package can. The sheet-shape positive electrode has a positive electrode mixture containing a positive electrode active material, a conductive assistant, and a binder formed on a current collector, and a plurality of recessed parts are formed on the surface on the opposite side to the current collector of the positive electrode mixture layer. It is preferable that the recessed parts are formed by embossing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylindrical non-aqueous electrolyte primary battery, and more particularly to a cylindrical non-aqueous electrolyte primary battery having a high capacity and excellent heavy load discharge characteristics.

  As a cylindrical nonaqueous electrolyte primary battery, an electrode winding body formed by winding a sheet-like positive electrode and a sheet-like negative electrode through a separator is provided in a cylindrical outer can together with the nonaqueous electrolyte. What is structured is known. And in the positive electrode of such a cylindrical non-aqueous electrolyte primary battery, for example, a positive electrode active material, a conductive additive, a binder and the like are mixed to form a positive electrode mixture, which is uniformly stretched by a press or the like to form a sheet The positive electrode mixture sheet is used by forming a positive electrode material mixture layer made of a positive electrode material mixture sheet on the current collector by pressing the positive electrode material mixture sheet with a metal foil or the like as a current collector and pressing it. (For example, Patent Document 1).

  In recent years, there has been a demand for improvement in load characteristics and capacity of cylindrical nonaqueous electrolyte primary batteries. Here, when improving a cylindrical non-aqueous electrolyte primary battery from the point of a positive electrode, it is possible to hold | maintain more non-aqueous electrolyte to a positive electrode, for example.

  Since the positive electrode according to the cylindrical non-aqueous electrolyte primary battery has a positive electrode mixture layer containing a positive electrode active material as described above, the density of the positive electrode mixture layer is reduced, By successfully forming voids in the positive electrode mixture layer, it is possible to hold the non-aqueous electrolyte in the voids.

  However, if the retention in the non-aqueous electrolyte is emphasized and the voids in the positive electrode mixture layer are made too large, the amount of the positive electrode active material in the positive electrode mixture layer is reduced. There is a risk of not being able to keep. On the other hand, since the gap formed in the positive electrode mixture layer is compressed to a certain extent when the electrode is wound, the emphasis is on securing the necessary strength when the electrode is wound. If the formation of the voids is restricted, the voids are reduced by the above-described compression, so that it is difficult to secure a void enough to sufficiently hold the non-aqueous electrolyte and exhibit the above-described effect satisfactorily.

  On the other hand, as a technique for increasing the amount of the non-aqueous electrolyte retained in the vicinity of the electrode, for example, in Patent Document 2, the separator has a laminated structure of a denser microporous film layer and a nonwoven fabric layer having more voids. Thus, a technique for increasing the amount of non-aqueous electrolyte retained near the electrode on the side in contact with the nonwoven fabric layer has been proposed.

JP 2005-32584 A JP 2006-139918 A

  According to the technique described in Patent Document 2, the non-woven electrolyte layer in the vicinity of the positive electrode is held by arranging the non-woven fabric layer of the separator having the above laminated structure on the positive electrode side to constitute the cylindrical non-aqueous electrolyte primary battery. The amount can be increased, and a certain effect can be ensured. However, since the separator has a laminated structure, the volume of the separator that is not involved in the battery capacity is increased. For this reason, the technique described in Patent Document 2 still has room for improvement in that it is difficult to avoid a certain decrease in capacity.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a cylindrical non-aqueous electrolyte primary battery having excellent load characteristics and a large capacity.

  The cylindrical non-aqueous electrolyte primary battery of the present invention that has achieved the above object has an electrode winding body formed by winding a sheet-like positive electrode and a sheet-like negative electrode through a separator in a cylindrical outer can. The sheet-like positive electrode is a battery in which a positive electrode mixture layer containing a positive electrode active material, a conductive additive and a binder is formed on a current collector. A plurality of recesses are formed on the surface opposite to the body side.

  In the present invention, a plurality of recesses are formed on the surface of the positive electrode active material layer of the positive electrode, and the nonaqueous electrolyte is held in these recesses to increase the amount of nonaqueous electrolyte retained in the vicinity of the positive electrode. The surface area of the mixture layer, that is, the reaction area is increased. In the non-aqueous electrolyte primary battery of the present invention, by adopting the above-described configuration, while suppressing the decrease in battery capacity as much as possible, the effect of increasing the non-aqueous electrolyte holding amount in the vicinity of the positive electrode, The load characteristic is enhanced by synergistically functioning with the reaction area increase in the agent layer.

  According to the present invention, it is possible to provide a cylindrical non-aqueous electrolyte primary battery having excellent load characteristics and a large capacity.

  FIG. 1 is a longitudinal side view showing an example of the non-aqueous electrolyte primary battery of the present invention. In FIG. 1, a nonaqueous electrolyte primary battery 1 includes a bottomed cylindrical outer can 2 having an upper opening, a sheet-like positive electrode 4 and a sheet-like negative electrode 5 loaded in the outer can 2, and a separator 6. And a sealing structure that seals an upper opening of the outer can 2, an electrode winding body 3 that is wound through a non-aqueous electrolyte (hereinafter simply referred to as “electrolyte”). In other words, the non-aqueous electrolyte primary battery 1 of FIG. 1 includes a sheet-like positive electrode 4 and a sheet-like negative electrode 5 in a space surrounded by an outer can 2 and a sealing structure that seals the upper opening of the outer can 2. Is wound through a separator 6 and has a power generation element such as an electrode winding body 3 and an electrolytic solution. The outer can 2 is made of iron or stainless steel.

  The sealing structure is attached to the cover plate 8 fixed to the inner peripheral edge of the upper opening of the outer can 2 and the opening formed in the center of the cover plate 8 through an insulating packing 9 made of polypropylene or the like. Terminal body 10 and insulating plate 11 disposed below cover plate 8. The insulating plate 11 is formed in a round plate shape that opens upward with an annular side wall 13 standing on the periphery of the disk-shaped base portion 12, and a gas passage 14 is opened at the center of the base portion 12. Yes. The cover plate 8 is fixed to the inner peripheral edge of the upper opening of the outer can 2 by laser welding or a crimp seal through packing while being received by the upper end of the side wall 13. As a countermeasure when the battery internal pressure suddenly increases, a thin portion (vent) can be provided on the lid 8 or the can bottom 2a of the outer can 2. The positive electrode 4 and the lower surface of the terminal body 10 are connected by a positive electrode lead body 15. Further, the negative electrode lead body 16 attached to the negative electrode 5 is welded to the upper inner surface of the outer can 2. Hereinafter, the configuration of the nonaqueous electrolyte primary battery of the present invention will be described in detail.

<Positive electrode>
As the sheet-like positive electrode according to the present invention, for example, a positive electrode mixture (slurry) obtained by blending a positive electrode active material with a conductive additive or a binder and adding water or the like as necessary is used using a roll or the like. Rolled into a preliminary sheet, dried and pulverized, then rolled into a sheet shape again and stacked on one or both sides of the current collector. What integrated the electric body and formed the layer (positive electrode mixture layer) which consists of a positive mix sheet on the single side | surface or both surfaces of a collector can be used.

  Specifically, for example, the current collector is overlapped by 3 mm so that the current collector is located several mm inside the two positive electrode mixture sheets, and 3 to 3 from the end in the length direction that becomes the winding start end. A sheet-like positive electrode can be produced by pressing a 10 mm portion. From the viewpoint of work, it is preferable that the two positive electrode mixture sheets and the positive electrode current collector are integrated prior to the production of the electrode winding body. The sheet may be integrated when the electrode winding body is wound, and there is no particular problem in terms of characteristics even by such a manufacturing method.

  In addition, the sheet-like positive electrode according to the present invention is not limited to those manufactured by the above manufacturing method, and may be manufactured by other manufacturing methods. For example, even a positive electrode manufactured by a manufacturing method in which a positive electrode mixture slurry is applied to one or both sides of a current collector and dried, and subjected to a press treatment as necessary to form a positive electrode mixture layer on the current collector. Good.

  Examples of the positive electrode active material include manganese dioxide, carbon fluoride, lithium cobalt composite oxide, spinel-type lithium manganese composite oxide, and the like.

  Moreover, as a conductive support agent, graphite, carbon black (Ketjen black etc.), acetylene black etc. are mentioned, for example, These may be used individually by 1 type, and may use 2 or more types together. As the binder, fluorine resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF); rubber binders, and the like can be used. In the case of a fluororesin such as PTFE or PVDF, a dispersion type or a powder type may be used, but a dispersion type is particularly preferable.

  In the positive electrode mixture layer relating to the sheet-like positive electrode, for example, the content of the positive electrode active material is 92 to 97% by mass, the content of the conductive additive is 2 to 4% by mass, and the content of the binder is 1 to 4% by mass. % Is preferable. In addition, the thickness of the positive electrode mixture layer (when formed on both sides of the current collector, the thickness per side) is preferably, for example, 100 to 2000 μm.

It is preferable that the density of the positive mix layer concerning a sheet-like positive electrode is 2.1-2.8 g / cm < ³ >, for example. In addition, the density of a sheet-like positive electrode as used in this specification is a value calculated | required by the volume and weight of the positive mix layer in a dry state.

From the viewpoint of improving the load characteristics of the non-aqueous electrolyte primary battery (especially the discharge characteristics at medium load), carbon black (particularly ketjen black) having a BET specific surface area of 400 to 2000 m ² / g is used as a conductive additive. More preferably, the content of the conductive additive in the positive electrode mixture layer is 2.0 to 4.0% by mass, and the density of the positive electrode mixture layer is 2.2 to 2.7 g / cm ^3. .

  In addition, the BET specific surface area of the conductive assistant referred to in this specification is a surface area measured and calculated using the BET formula which is a theoretical formula of multimolecular adsorption. is there. Moreover, the specific surface area measuring apparatus by the nitrogen adsorption method ("Macsorb HM model-1201" by Mounttech) was used for the measurement of the BET specific surface area of carbon black in the Example mentioned later.

  Examples of the current collector used for the positive electrode include those made of stainless steel such as SUS316, SUS430, and SUS444, and the forms thereof include plain weave metal mesh, expanded metal, lath net, punching metal, and foil (plate). Etc. can be exemplified. The thickness of the current collector is preferably, for example, 0.1 to 0.4 mm.

  It is desirable to apply a paste-like conductive material to the surface of the positive electrode current collector. When a positive electrode current collector having a three-dimensional structure is used, as in the case of using an essentially flat material such as a metal foil or a punching metal, the current collecting effect is remarkable by applying a conductive material. Improvement is observed. This is because not only the route in which the metal part of the mesh current collector is in direct contact with the positive electrode mixture layer but also the route through the conductive material filled in the mesh is effectively used. It is estimated to be.

  As the conductive material, for example, silver paste or carbon paste can be used. In particular, the carbon paste is suitable for reducing the manufacturing cost of the non-aqueous electrolyte primary battery because the material cost is lower than that of the silver paste and the contact effect is almost the same as that of the silver paste. As the binder for the conductive material, it is preferable to use a heat resistant material such as water glass or an imide binder. This is because the drying process is performed at a high temperature exceeding 200 ° C. when moisture in the positive electrode mixture layer is removed.

  The sheet-like positive electrode according to the present invention has a plurality of concave portions on the surface of the positive electrode mixture layer formed on the current collector as described above (the surface opposite to the surface in contact with the current collector). ing. These recesses increase electrolyte retention and increase the amount of electrolyte in the vicinity of the positive electrode, and also increase the surface area of the positive electrode mixture layer and increase the reaction area. Has achieved.

  As the concave portion on the surface of the positive electrode mixture layer, for example, a plurality of continuous concave portions such as a groove shape may be formed, or a plurality of concave portions such as discontinuous depressions may be formed. Also good.

  FIG. 2 shows an example in which the recess is groove-shaped. FIG. 2 is a plan view of the sheet-like positive electrode 4, and a groove-like recess 400 is formed on the surface of the positive electrode mixture layer 40 of the sheet-like positive electrode 4 so as to draw a rhombus in a plan view.

  FIG. 3 shows a cross-sectional view taken along the line I-I of FIG. 2. As shown in FIG. 3, the sheet-like positive electrode 4 has a groove shape on the surface of the positive electrode mixture layer 40 on the upper side of the current collector 42. And a groove-shaped recess 410 is also formed on the surface of the positive electrode mixture layer 41 on the lower side of the current collector 42.

  FIG. 4 shows another example in the case of a concave groove shape. On the surface of the positive electrode mixture layer 40 in the sheet-like positive electrode 4 shown in FIG. 4, groove-like recesses 400 are formed so as to draw a lattice in plan view (that is, draw a square).

  When the recess is groove-shaped, there is no particular limitation on the arrangement of the recess. For example, in the plan view of the sheet-like positive electrode, the groove-shaped recess makes a triangle, square (excluding the diamond, for example, as shown in FIG. 4), A plurality of groove-like recesses may be arranged so as to draw a diamond shape (for example, the one shown in FIG. 2), and a plurality of groove-like recesses may be arranged in parallel so as not to intersect each other. May be. Among these, from the viewpoint of further enhancing the flexibility improvement effect of the sheet-like positive electrode described later, one of the diagonal lines is a rhombus parallel to the longitudinal direction of the sheet-like positive electrode (that is, the winding direction in the electrode winding body). It is more preferable to arrange the groove-shaped recess so as to draw (for example, as shown in FIG. 2).

  The depth of the groove-like recess is preferably 1/2 or less, more preferably 1/3 or less of the thickness of the positive electrode mixture layer. If the depth of the concave portion is too large, the binder in the positive electrode mixture layer may be cut due to the formation of the concave portion, and the positive electrode may be cracked during winding due to the concave portion. It is. In addition, from the viewpoint of more effectively exerting the effect of improving the load characteristics of the battery by forming the recess, the depth of the groove-like recess is preferably 1/10 or more of the thickness of the positive electrode mixture layer. More preferably, / 5 or more.

  Further, the width of the groove-shaped recess (the width of the opening) is preferably about the same as the depth of the groove-shaped recess, and more specifically 0.05 mm to 0.5 mm.

  A plurality of recesses are formed on the surface of the positive electrode mixture layer. For example, when groove-like recesses are formed as shown in FIGS. 2 and 4, the interval between adjacent recesses arranged in parallel is 1 mm. The thickness is preferably 4 mm or less.

  There is no restriction | limiting in particular about the shape of the cross section of a groove-shaped recessed part, In addition to U shape as shown in FIG. 3, V shape etc. are mentioned.

  FIG. 5 shows an example in which the concave portion has a discontinuous hollow shape, and a plurality of concave portions 400 having a circular opening are formed on the surface of the positive electrode mixture layer 40 in the sheet-like positive electrode.

  When the concave portion is formed in a discontinuous concave shape, the shape is not particularly limited, and for example, the shape of the opening in plan view may be various shapes such as a triangle and a square in addition to the circular shape shown in FIG. it can. There is no particular restriction on the arrangement of the concave portions, but the concave portions are arranged so as to be almost uniform over the entire concave portion formation place without arranging the concave portions densely at a specific location or forming a small portion of the concave portion. It is preferable to arrange.

  The depth of the recess when the recess is a discontinuous recess is preferably 1/2 or less, and 1/3 or less of the thickness of the positive electrode mixture layer, similarly to the case where the recess is a groove. It is more preferable that If the depth of the concave portion is too large, the binder in the positive electrode mixture layer may be cut due to the formation of the concave portion, and the positive electrode may be cracked during winding due to the concave portion. It is. In addition, in the case where the concave portion is a discontinuous concave shape, the depth of the concave portion from the viewpoint of more effectively exerting the effect of improving the load characteristics of the battery by forming the concave portion, as in the case where the concave portion is a groove shape. Is preferably 1/10 or more, more preferably 1/5 or more of the thickness of the positive electrode mixture layer.

In the case where the concave portion is a discontinuous concave shape, the size of each concave portion is not particularly limited. For example, the area of the opening portion in a plan view is preferably set to 0.004 to 0.4 mm ² . Moreover, when a recessed part is a discontinuous hollow shape, it is preferable that the distance between adjacent recessed parts shall be 1-4 mm, for example.

  In any case where the concave portion is a groove shape or the concave portion is a discontinuous concave shape, from the viewpoint of more reliably exerting an effect of improving the load characteristics of the battery by forming the concave portion, The total area of the openings is preferably 10% or more, more preferably 20% or more, of the total area of the positive electrode mixture layer in plan view. In addition, if the total area of the opening portions of the recesses in plan view is too large, the filling amount of the positive electrode active material may be reduced. Therefore, the total area of the opening portions of the recesses in plan view is the positive electrode mixture layer. Is preferably 50% or less, and more preferably 40% or less in the total area in plan view.

  As described above, the concave portion may be a groove shape or a discontinuous depression shape, but it is considered that the flow of the electrolytic solution becomes better and the discharge reaction proceeds more smoothly. Moreover, since it is thought that the softness | flexibility improvement effect of the positive mix layer mentioned later is acquired more easily, it is more preferable that it is groove shape.

  The concave portion on the surface of the positive electrode mixture layer is preferably formed by embossing. By forming by embossing, it is possible to efficiently form the recesses without causing a decrease in the strength of the positive electrode.

  Specifically, after the positive electrode mixture layer is formed on the current collector, a concave portion is formed on the surface of the positive electrode mixture layer by passing a roll (embossing roll) for forming a concave portion or pressurizing in a stamp type. It can be formed, but other means may be used. In addition, when forming the recessed part using an embossing roll, you may heat an embossing roll to 50-150 degreeC.

  For example, when PTEF is used as the binder related to the positive electrode mixture layer, when the concave portions are formed by embossing, the PTFE fibrils are stretched, so that the flexibility of the positive electrode mixture layer can be increased. Therefore, in this case, even if the density of the positive electrode mixture layer is increased in order to increase the filling amount of the positive electrode active material, cracking of the positive electrode mixture layer during winding can be suppressed. can do.

<Negative electrode>
Examples of the negative electrode that can be used in the present invention include a sheet-like negative electrode as shown in FIG. 1. The sheet-like negative electrode includes, for example, a metal lithium foil that is a negative electrode active material and a metal foil that is a negative electrode current collector. Composed. Examples of the material for the metal lithium foil include not only metal lithium but also lithium alloys such as lithium-aluminum. The thickness of the metal lithium foil is preferably 0.15 to 0.4 mm, for example.

  Examples of the material for the negative electrode current collector include copper, nickel, iron, and stainless steel. Since the internal volume of the outer can decreases by the thickness of the negative electrode current collector, the thickness dimension of the negative electrode current collector is preferably as small as possible, specifically, for example, 0.1 mm or less. Recommended. That is, if the negative electrode current collector is too thick, the amount of metal lithium foil or the like that is the negative electrode active material must be reduced, which may lead to a decrease in battery capacity. Moreover, since it will be easy to tear when a negative electrode collector is too thin, it is desirable that the thickness of a negative electrode collector be 0.005 mm or more. The width of the negative electrode current collector is preferably the same as or wider than the width of the metal lithium foil, and the area is 100 to 130% of the area of the metal lithium foil arranged on one side. It is preferable. By making the area of the negative electrode current collector as described above, the width of the negative electrode current collector is the same as or wider than the width of the metal lithium foil, and the length becomes longer. It is possible to prevent the lithium foil from being cut and the electrical connection from being cut off.

<Electrolyte>
Examples of the electrolyte solution according to the non-aqueous electrolyte primary battery of the present invention include those prepared by dissolving LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , and the like as an electrolyte in a non-aqueous solvent such as an organic solvent. Examples of the solvent include a mixture of a cyclic ester such as ethylene carbonate and propylene carbonate with a chain ether such as dimethoxyethane and a chain ester such as dimethyl carbonate. The concentration of the electrolyte in the electrolytic solution is preferably 0.3 to 1.5 mol / l.

<Separator>
As a separator, the separator made from a microporous film and the separator made from a nonwoven fabric which are employ | adopted as a conventionally well-known nonaqueous electrolyte primary battery are applicable.

  Examples of the resin constituting the microporous film serving as the separator include polyolefins such as polyethylene (PE) and polypropylene (PP); polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyphenylene sulfide (PPS) And so on. Examples of such commercially available microporous films include “Hypore” (trade name) manufactured by Asahi Kasei Corporation, “Setilla” (trade name) manufactured by Tonen Chemical Co., Ltd., and the like.

  Moreover, as a nonwoven fabric used as a separator, for example, polyolefins such as polyethylene (PE) and polypropylene (PP); polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyphenylene sulfide (PPS); Those produced by various known production methods can be used.

  Furthermore, you may use the separator of the structure which laminated | stacked the said microporous film and the said nonwoven fabric.

  The thickness of the separator is preferably 15 to 50 μm, for example.

  In describing the non-aqueous electrolyte primary battery of the present invention, FIGS. 1 to 5 were referred to. However, these drawings are only examples of the battery of the present invention, and the battery of the present invention is not limited to these. It is not necessarily limited to what is illustrated in the drawings. Moreover, FIGS. 1-5 is for demonstrating the structure of the battery of this invention, Comprising: The size etc. are not necessarily exact.

  The non-aqueous electrolyte primary battery of the present invention is excellent in load characteristics and has a large capacity. Therefore, taking advantage of such characteristics, it can be used as a power source for fire alarms for houses, as well as various types of gas, electricity, water, etc. It can be applied to various uses to which a conventionally known non-aqueous electrolyte primary battery is applied, including a power source use of a meter.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention. In this embodiment, a cylindrical nonaqueous electrolyte primary battery having an outer diameter of 17 mm and a height of 45 mm will be described as an example of a cylindrical nonaqueous electrolyte primary battery. In addition, "%" used in a present Example is a mass reference | standard (mass%) unless there is particular notice.

Example 1
For the cylindrical nonaqueous electrolyte primary battery of Example 1, [Preparation of positive electrode], [Preparation of negative electrode], [Preparation of wound electrode], [Assembly of battery], [Post-treatment (preliminary discharge, aging)] Will be described in the order.

[Production of positive electrode]
First, a positive electrode mixture (in mass ratio, solid content: water content = 100: 30) was prepared by the following procedure. Carbon black having a BET specific surface area of 1000 m ² / g: 3% and manganese dioxide (manufactured by Tosoh Corporation): 92% were mixed for 5 minutes in a dry manner using a planetary mixer, and then water was added to a solid content of 20% ( Mass ratio) and mixed for 5 minutes. Prepare PTFE dispersion ("D-1" manufactured by Daikin Industries, Ltd.) in an amount corresponding to 5% of the solid content of the positive electrode mixture, dilute it with the remaining water, and add to the above mixture And mixed for 5 minutes to obtain a positive electrode mixture.

Using the above positive electrode mixture, two rolls having a diameter of 250 mm, adjusting the roll temperature to 125 ± 5 ° C., press pressure: 7 ton / cm, roll interval: 0.4 mm, rotation speed: 10 rpm The sheet was rolled and rolled. The positive electrode mixture (preliminary sheet) that passed through the roll was dried at 105 ± 5 ° C. until the residual moisture was 2% or less. Next, the dried preliminary sheet was pulverized using a pulverizer, and then formed into a sheet by a roll again. A flat plate for forming a positive electrode mixture layer by adjusting the roll interval to 0.6 ± 0.05 mm, forming a sheet under the conditions of roll temperature: 125 ± 10 ° C., press pressure: 7 ton / cm, rotation speed: 10 rpm A sheet was obtained. The obtained flat sheet has a thickness of 1.0 mm and corresponds to 5.9% of the inner diameter of the outer can. The density of the flat sheet was 2.5 g / cm ³ , and the porosity determined by the above method was 42%.

  By passing this flat sheet between two embossing rolls having a diameter of 100 mm, a groove-shaped recess is formed on one side of the flat sheet so as to draw a rhombus in a plan view as shown in FIG. Thus, a positive electrode mixture sheet was obtained. In addition, the said groove-shaped recessed part was formed substantially uniformly over the whole positive electrode mixture sheet single side | surface. The depth of the formed groove-like recess is 0.2 mm, which corresponds to 1/5 of the thickness of the positive electrode mixture sheet (that is, the positive electrode mixture layer). The width of the groove-shaped recess was 0.2 mm, and the interval between the recesses was 1.5 mm. The cross-sectional shape of the recess was U-shaped as shown in FIG. When the positive electrode mixture sheet was viewed in plan, the total area of the openings of the recesses was about 25% of the total area of the positive electrode mixture sheet in plan view.

  The positive electrode mixture sheet was cut to obtain an inner periphery positive electrode mixture sheet having a width of 37 mm and a length of 51 mm, and an outer periphery positive electrode mixture sheet having a width of 37 mm and a length of 62 mm.

As the positive electrode current collector, an expanded metal made of stainless steel (SUS316) having a thickness of 0.3 mm was used. This expanded metal was cut to a width of 34 mm and a length of 56 mm, and a stainless steel ribbon having a thickness of 0.1 mm and a width of 3 mm was attached to the central portion in the length direction by resistance welding as a positive electrode lead body. . Further, a carbon paste (manufactured by Nippon Graphite Co., Ltd.) was applied to the expanded metal so as not to crush the mesh, and then dried at a temperature of 105 ± 5 ° C. to obtain a positive electrode current collector. The coating amount of the carbon paste was set to 5 mg / cm ² after drying.

  Next, in a state where the positive electrode current collector is interposed between the positive electrode mixture sheet for the inner periphery and the positive electrode mixture sheet for the outer periphery, only one end in the length direction is fixed and the three parties are integrated. . Specifically, the positive electrode mixture sheet for the inner periphery and the positive electrode mixture sheet for the outer periphery are aligned with one end in the length direction, and the end of the positive electrode current collector is composed of two positive electrode mixture sheets. Set the two so that they do not protrude from one end, and in that state, press the 5mm portion of the two positive electrode mixture sheets from one end where both are aligned, and unite the three. did. Thereafter, the two positive electrode mixture sheets and the positive electrode current collector integrated with each other were dried with hot air at 250 ± 10 ° C. for 6 hours, the width was 37 mm, and the side opposite to the current collector side of the positive electrode mixture layer A sheet-like positive electrode having a plurality of recesses on the surface was obtained.

[Production of negative electrode]
The negative electrode has a width: 39 mm, a length: 170 mm, a thickness: 10 μm on a copper foil (negative electrode current collector), a width: 37 mm, a length: 87 mm, a thickness: 0.30 mm metal lithium foil, and a width: 37 mm. A metal lithium foil having a length of 50 mm and a thickness of 0.30 mm was arranged. First, a negative electrode lead made of nickel having a width of 3 mm, a length of 20 mm, and a thickness of 0.1 mm was pressure-bonded to a metal lithium foil having a length of 50 mm. Thereafter, the two metal lithium foils were placed on the copper foil in a separated state to produce a sheet-like negative electrode.

[Production of wound electrode body]
As a separator, a microporous polyethylene film [“Hypore” (trade name) manufactured by Asahi Kasei Co., Ltd.] having a width of 44 mm, a length of 170 mm, and a thickness of 25 μm was prepared.

  Adhesive tape was affixed on the copper foil of a sheet-like negative electrode, and the separator was affixed on this adhesive tape by heat welding. Next, the heat-welded portion of the separator was sandwiched between two winding cores having a diameter of 3.5 mm and wound once. Next, after winding the negative electrode together with the separator once, the side on which the sheet-like positive electrode was fixed was placed on the winding core side and wound. After winding, the copper foil covered the outermost periphery. The electrode winding body was obtained by the above.

[Battery assembly]
An assembly process of the cylindrical non-aqueous electrolyte primary battery will be described with reference to FIG. An insulating plate made of polypropylene having a thickness of 0.2 mm is inserted into the inner bottom portion 2a of the bottomed cylindrical outer can 2 made of Ni-plated iron can, and the electrode winding body 3 and the positive electrode lead body 15 are inserted thereon. Was inserted in a posture facing upward. The negative electrode lead body 16 of the electrode body 3 was resistance welded to the inner surface of the outer can 2, and the positive electrode lead body 15 was resistance welded to the lower surface of the terminal plate 10 of the battery lid 8 after inserting the insulating plate 11. At this point, the insulation resistance was measured and it was confirmed that there was no short circuit. The battery lid 8 was made of Ni-plated iron.

As the electrolyte, a non-aqueous solution prepared by dissolving LiCF ₃ SO ₃ at a concentration of 0.5 mol / l in a mixed solvent in which EC, PC, and DME are mixed at a volume ratio of 10: 5: 85 is prepared. Then, 3.5 ml of this was injected into the outer can 2. The injection was divided into three times, and the whole amount was injected while reducing the pressure in the final step. After injecting the electrolytic solution, the battery lid 8 is fitted into the upper opening of the outer can 2, and the inner peripheral portion of the opening end of the outer can 2 and the outer peripheral portion of the battery lid 8 are welded by laser welding. 2 openings were sealed.

[Post-treatment (preliminary discharge, aging)]
The sealed battery was preliminarily discharged with a resistance of 1Ω for 30 seconds, stored at 70 ° C. for 6 hours, and then subjected to a secondary preliminary discharge with a constant resistance of 1Ω for 1 minute. The battery after the preliminary discharge was aged at room temperature for 7 days, and the open circuit voltage was measured to confirm that a stable voltage was obtained. The outer diameter was 17.0 mm and the total height was 45.0 mm. A water electrolyte primary battery was obtained. The content of EC in all the solvents of the cylindrical non-aqueous electrolyte primary battery is 10% by volume.

Example 2
By passing the flat sheet between two embossing rolls having a diameter of 100 mm, a groove-shaped recess is formed on one side of the flat sheet so as to draw a square in plan view as shown in FIG. Thus, a positive electrode mixture sheet was obtained. In addition, the said groove-shaped recessed part was formed substantially uniformly over the whole positive electrode mixture sheet single side | surface.

  The depth of the formed groove-like recess is 0.2 mm, which corresponds to 1/5 of the thickness of the positive electrode mixture sheet (that is, the positive electrode mixture layer). The width of the groove-shaped recess was 0.2 mm, and the interval between the recesses was 2 mm. The cross-sectional shape of the recess was U-shaped as shown in FIG. When the positive electrode mixture sheet was viewed in plan, the total area of the opening portions of the recesses was about 15% of the total area of the positive electrode mixture sheet in plan view.

  A cylindrical non-aqueous electrolyte primary battery was produced in the same manner as in Example 1 except that the positive electrode mixture sheet was used.

Example 3
By passing the flat sheet between two embossing rolls having a diameter of 100 mm, as shown in FIG. 5, a circular recess is formed on one side of the flat sheet as shown in FIG. Thus, a positive electrode mixture sheet was obtained. In addition, the said hollow-shaped recessed part was formed substantially uniformly over the whole positive electrode mixture sheet single side | surface.

The depth of the formed recess is 0.2 mm, which corresponds to 1/5 of the thickness of the positive electrode mixture sheet (that is, the positive electrode mixture layer). The size of the recess was such that the area of the opening was about 0.03 mm ^{2 in} plan view. The cross-sectional shape of the recess was U-shaped as shown in FIG. When the positive electrode mixture sheet was viewed in plan, the total area of the openings of the recesses was about 8% of the total area of the positive electrode mixture sheet in plan view.

  A cylindrical non-aqueous electrolyte primary battery was produced in the same manner as in Example 1 except that the positive electrode mixture sheet was used.

Comparative Example 1
A cylindrical nonaqueous electrolyte primary battery was produced in the same manner as in Example 1 except that the flat sheet produced in the same manner as in Example 1 was used as it was as the positive electrode mixture sheet.

[Discharge capacity measurement]
For the cylindrical non-aqueous electrolyte primary batteries of Examples 1 to 3 and Comparative Example 1, the discharge capacity was measured when a continuous discharge of 5 mA at 20 ° C. and a continuous discharge of 40 mA at 20 ° C. were respectively performed to obtain a final voltage of 2V. did. In addition, the number of samples of each battery was five, and the average value was made into the discharge capacity of the battery of each Example and a comparative example. In addition, for the batteries of the examples and comparative examples, the discharge capacity due to continuous discharge at 40 mA was divided by the discharge capacity due to continuous discharge at 5 mA, and the capacity ratio expressed as a percentage was obtained. Characteristics were evaluated. Table 1 shows the discharge capacity due to continuous discharge at 5 mA (5 mA discharge), the discharge capacity due to continuous discharge at 40 mA (40 mA discharge), and the capacity ratio.

  As is clear from Table 1, the cylindrical nonaqueous electrolyte primary batteries of Examples 1 to 3 in which a plurality of recesses were formed on the surface of the positive electrode mixture layer opposite to the current collector side were the batteries of Comparative Example 1. The discharge capacity is larger than And the cylindrical non-aqueous electrolyte primary batteries of Examples 1 to 3 did not have a large difference between the discharge capacity at 5 mA discharge, which is a light load, and the discharge capacity at 40 mA discharge, and the capacity ratio Is high, the load characteristics are also good.

[Electrode flexibility check test]
Table 2 shows the results of disassembling the electrode winding bodies according to the cylindrical nonaqueous electrolyte primary batteries of Examples 1 to 3 and Comparative Example 1 and observing the state of the surface of the positive electrode serving as the outermost periphery. Observation was performed visually.

  As is apparent from Table 2, the surface of the positive electrode according to the cylindrical nonaqueous electrolyte primary batteries of Examples 1 to 3 has no cracks after winding, or the cracks are slight, Many cracks can be confirmed on the surface of the positive electrode according to the cylindrical non-aqueous electrolyte primary battery of Comparative Example 1. Therefore, it can be confirmed that the positive electrode mixture layer of the positive electrode according to the batteries of Examples 1 and 2 is particularly excellent in flexibility.

It is a longitudinal cross-sectional schematic diagram which shows an example of the cylindrical nonaqueous electrolyte primary battery of this invention. It is a plane schematic diagram which shows an example of the sheet-like positive electrode which concerns on the cylindrical nonaqueous electrolyte primary battery of this invention. It is the II sectional view taken on the line of FIG. It is a plane schematic diagram which shows the other example of the sheet-like positive electrode which concerns on the cylindrical nonaqueous electrolyte primary battery of this invention. It is a plane schematic diagram which shows the other example of the sheet-like positive electrode which concerns on the cylindrical nonaqueous electrolyte primary battery of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical non-aqueous electrolyte primary battery 2 Exterior can 3 Electrode winding body 4 Sheet-like positive electrode 5 Sheet-like negative electrode 6 Separator 8 Cover plate 10 Terminal body 40, 41 Positive electrode mixture layer 42 Positive electrode collector 400, 410 Recessed part

Claims (4)

A cylindrical non-aqueous electrolyte primary battery having an electrode winding body formed by winding a sheet-like positive electrode and a sheet-like negative electrode through a separator in a cylindrical outer can,
The sheet-like positive electrode is formed by forming a positive electrode mixture layer containing a positive electrode active material, a conductive additive and a binder on a current collector,
A cylindrical non-aqueous electrolyte primary battery, wherein a plurality of recesses are formed on the surface of the positive electrode mixture layer opposite to the current collector side.   The cylindrical nonaqueous electrolyte primary battery according to claim 1, wherein the plurality of recesses on the surface of the positive electrode mixture layer have a groove shape.   The cylindrical non-aqueous electrolyte primary battery according to claim 1 or 2, wherein a plurality of concave portions on the surface of the positive electrode mixture layer are formed by embossing.   The cylindrical nonaqueous electrolyte primary battery according to any one of claims 1 to 3, wherein the binder contained in the positive electrode mixture layer is polytetrafluoroethylene.

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