JP5620811B2 - Cylindrical non-aqueous electrolyte primary battery - Google Patents

Description

  The present invention relates to a cylindrical non-aqueous electrolyte primary battery having excellent heavy load pulse discharge characteristics and good productivity.

  Cylindrical non-aqueous electrolyte primary batteries may be required to be able to take out a large current instantaneously, that is, excellent in heavy load pulse discharge characteristics, as in applications such as gas meter shut-off valves and wireless communications. is there. In the current cylindrical non-aqueous electrolyte primary battery, for example, by using an electrode group having a winding structure in which a positive electrode and a negative electrode are wound in a spiral shape via a separator, a large electrode area is secured, It corresponds to the request of.

  In addition, in the cylindrical non-aqueous electrolyte primary battery, in addition to using a wound electrode group, a technique for forming a negative electrode used for the electrode group by laminating a metal lithium foil and an aluminum foil is also available. It has been proposed (for example, Patent Documents 1 and 2). According to the techniques described in Patent Document 1 and Patent Document 2, in the battery, the metal lithium foil and the aluminum foil of the negative electrode are electrochemically alloyed to form a lithium-aluminum alloy, which is pulverized. The surface area of the negative electrode can be further increased, and the heavy load pulse discharge characteristics of the battery can be further enhanced.

JP 2007-250414 A JP 2009-266715 A

  However, while the batteries described in Patent Document 1 and Patent Document 2 have high heavy-load pulse discharge characteristics, there is still room for improvement in terms of productivity. In addition, it is expected that the cylindrical non-aqueous electrolyte primary battery will be required to have a heavy-load pulse discharge characteristic that exceeds that of the conventional battery as the application equipment is improved.

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

  The cylindrical non-aqueous electrolyte primary battery of the present invention that has achieved the above-described object has a wound structure electrode group in which a positive electrode containing manganese dioxide and a negative electrode are wound in a spiral shape via a separator. The negative electrode has a metal lithium-containing layer composed of only one continuous layer on one side of the current collector, and the surface of the current collector on which the metal lithium-containing layer is formed 85% or more of the area is covered with the metal lithium-containing layer, and a lithium-aluminum alloy is formed on at least a part of the surface of the metal lithium-containing layer opposite to the current collector side. It is characterized by that.

  According to the present invention, a cylindrical non-aqueous electrolyte primary battery having excellent heavy load pulse discharge characteristics and good productivity is provided.

It is a longitudinal section showing typically an example of the cylindrical nonaqueous electrolyte primary battery of the present invention. It is a cross-sectional view of the cylindrical non-aqueous electrolyte primary battery shown in FIG. It is a cross-sectional view which represents typically an example of the conventional cylindrical nonaqueous electrolyte primary battery.

  In FIG. 1, the longitudinal cross-sectional view which represents typically an example of the cylindrical nonaqueous electrolyte primary battery of this invention is shown. A cylindrical non-aqueous electrolyte primary battery 1 shown in FIG. 1 has a bottomed cylindrical outer can 2 having an upper opening, and a positive electrode 4 and a negative electrode 5 loaded in the outer can 2 with a separator interposed therebetween. The electrode group 3 has a spirally wound structure, a non-aqueous electrolyte (hereinafter simply referred to as “electrolyte”), and a sealing structure that seals the upper opening of the outer can 2. In other words, the cylindrical non-aqueous electrolyte primary battery 1 in FIG. 1 has the positive electrode 4 and the negative electrode 5 separated in a space surrounded by the outer can 2 and the sealing structure that seals the upper opening of the outer can 2. 6 has a power generation element such as an electrode group 3 having a wound structure formed by winding via 6 and an electrolytic solution. The outer can 2 is made of iron, stainless steel, or the like.

  The sealing structure is attached to the cover plate 7 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 7 through an insulating packing 8 made of polypropylene or the like. Terminal body 9 and insulating plate 10 disposed under cover plate 7. The insulating plate 10 is formed in a round plate shape having an annular side wall 12 standing on the periphery of the disk-shaped base portion 11 and opening upward, and a gas passage 13 is opened at the center of the base portion 11. Yes. The cover plate 7 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 12. As a countermeasure when the battery internal pressure suddenly increases, a thin portion (vent) can be provided on the lid 7 or the can bottom 2a of the outer can 2. The positive electrode 4 and the lower surface of the terminal body 9 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. Reference numeral 14 denotes an insulating plate disposed inside the can bottom 2 a of the outer can 2.

  FIG. 2 shows a cross-sectional view of the cylindrical non-aqueous electrolyte primary battery shown in FIG. As shown in FIG. 2, the electrode group 3 having a winding structure is formed by winding a sheet-like positive electrode 4 and a sheet-like negative electrode 5 with a separator 6 interposed therebetween, and is formed in a substantially cylindrical shape as a whole. Has been. In the cylindrical non-aqueous electrolyte primary battery shown in FIG. 2, the positive electrode 4 has a structure in which two positive electrode mixture sheets 41 and 42 are laminated via a current collector 43. The negative electrode 5 has a structure in which a metallic lithium-containing layer 51 and a current collector 52 are laminated. A lithium-aluminum alloy is formed on at least a part of the surface of the metallic lithium-containing layer 51 opposite to the current collector 52 side (however, in FIG. -The part where the aluminum alloy is formed is not shown separately).

  As shown in FIG. 2, the cylindrical non-aqueous electrolyte primary battery of the present invention includes a negative electrode having a metallic lithium-containing layer composed of only one continuous layer on one side of a current collector.

  Cross section schematically representing an example of a conventional cylindrical non-aqueous electrolyte primary battery having an electrode group of a wound structure formed using a negative electrode having a metallic lithium-containing layer with a lithium-aluminum alloy formed on the surface The figure is shown in FIG.

  As shown in FIG. 3, in the conventional cylindrical nonaqueous electrolyte primary battery 100, for example, a metal lithium foil for forming a metal lithium-containing layer 51 (a metal lithium foil and an aluminum for forming a lithium-aluminum alloy). (Including the case of a laminate with a foil), and the vicinity of the central portion of the current collector 52 is the winding center of the electrode group, and this portion is the exposed portion 53 of the current collector. The sheet of metal lithium foil was separated and disposed on the surface of the current collector 52. That is, in a negative electrode according to a conventional cylindrical nonaqueous electrolyte primary battery, a metal lithium-containing layer having a lithium-aluminum alloy formed on the surface is formed at or near the position corresponding to the winding center of the electrode group. Was not.

  The main reason is that, as shown in FIG. 3, the position corresponding to the winding center of the negative electrode and the portion in the vicinity thereof do not face the positive electrode. This is because the use of metallic lithium, which is considered to be useless, has been limited.

  However, as a result of intensive studies by the inventor, as shown in FIG. 2, the metal lithium-containing layer of the negative electrode is formed as a continuous layer, and the winding of the electrode group considered not to be involved in the discharge reaction. Contrary to the above expectation, if a metal lithium-containing layer is present even in a region that does not face the positive electrode at the center of rotation or in the vicinity thereof, a conventional battery (metal lithium-containing layer is replaced with two metal lithium foils). It has been found that the heavy-load pulse discharge characteristics are improved as compared with a battery having a negative electrode formed by separating them and using them.

  When the metal lithium-containing layer related to the negative electrode is a single continuous layer, like the negative electrode related to the conventional battery, two metal lithium foils are used, and these metal lithium-containing layers are arranged apart from each other. Compared with the case where it is formed, it is considered that the lithium-aluminum alloy that greatly contributes to the improvement of the heavy load pulse discharge characteristics can be formed more uniformly over the entire surface of the metal lithium-containing layer of the negative electrode. It is considered that the heavy load pulse discharge characteristics have been improved by making the discharge reaction uniform throughout.

  In addition, when an electrode group having a wound structure is formed using a negative electrode formed by disposing two metallic lithium foils on the surface of the negative electrode current collector, the negative electrode has thickness unevenness. Winding misalignment tends to occur when they are stacked and wound in a spiral shape, which has been a cause of battery productivity reduction.

  In contrast, in the present invention, the metal lithium-containing layer according to the negative electrode is not formed by using two metal lithium foils and separating them from each other, but using only one metal lithium foil. By forming the electrodes into a single continuous layer, the winding deviation when forming the electrode group having a wound structure is suppressed, and the productivity of the electrode group, and hence the productivity of the battery is improved.

  As used herein, “heavy load pulse discharge” means instantaneous discharge having a length of about 0.01 seconds to 10 seconds at a current of 300 to 3000 mA.

  The metal lithium-containing layer according to the negative electrode of the cylindrical non-aqueous electrolyte primary battery of the present invention is, for example, a part of one side of the metal lithium foil or lithium alloy foil (the side opposite to the side in contact with the current collector) And an aluminum foil formed on the surface of a metal lithium foil or lithium alloy foil in the presence of an electrolyte in the battery.

  If a lithium-aluminum alloy is formed on the surface of the metallic lithium-containing layer, the surface area increases due to micronization, and the reaction with the electrolyte solution on the negative electrode surface is suppressed, causing a decrease in battery characteristics. Formation of the organic film is suppressed. Therefore, the heavy load pulse discharge characteristics of the battery are improved.

  The battery of the present invention does not form a lithium-aluminum alloy in the battery, but a metal lithium foil having a lithium-aluminum alloy formed in advance on the surface or a metal lithium-containing layer formed using a lithium alloy foil. You may use the negative electrode which has.

  Examples of the lithium alloy foil that can be used for forming the metal lithium-containing layer include a lithium-magnesium alloy foil, a lithium-tin alloy foil, a lithium-zinc alloy foil, a lithium-antimony alloy foil, and a lithium-silicon alloy foil. . In the lithium alloys constituting these lithium alloy foils, the lithium content is preferably 90% by mass or more.

  The thickness of the metal lithium foil or lithium alloy foil used for forming the metal lithium-containing layer is preferably 0.05 to 0.4 mm, for example.

  When an aluminum foil is disposed on the surface of a metal lithium foil or lithium alloy foil and a metal lithium-containing layer having a lithium-aluminum alloy is formed on the surface, the thickness of the aluminum foil is, for example, a sufficient amount of lithium-aluminum alloy 3 μm or more from the viewpoint of ensuring the better effect of forming this, and suppressing the occurrence of winding failure due to cutting of the aluminum foil when winding the electrode group of the winding structure It is preferable that However, if the aluminum foil is too thick, the amount of aluminum not involved in the discharge increases and the discharge capacity of the battery may be reduced. Therefore, the thickness of the aluminum foil is preferably 15 μm or less.

  In the negative electrode, from the viewpoint of enhancing the heavy load pulse discharge characteristics of the battery and increasing the capacity, the area of the surface of the current collector on which the metal lithium-containing layer is formed is covered by the metal lithium-containing layer. The area is 85% or more, preferably 90% or more.

  Moreover, since the metal lithium content layer of a negative electrode is consumed with discharge reaction, there exists a possibility that a metal lithium content layer may be cut | disconnected if discharge of a battery is continued. Therefore, the area of the formation surface of the metal lithium-containing layer in the current collector of the negative electrode is made larger than the area of the metal lithium-containing layer so that the electrical connection can be maintained well even when the metal lithium-containing layer breaks. It is preferable to make it. Specifically, the area of the region covered with the metal lithium-containing layer in the area of the formation surface of the metal lithium-containing layer in the current collector is preferably 95% or less, for example.

  In the metal lithium-containing layer according to the negative electrode, from the viewpoint of improving the heavy load pulse discharge characteristics of the battery better, the area of the surface where the lithium-aluminum alloy is formed out of the surface area opposite to the current collector side. The area is preferably 85% or more, and more preferably 90% or more.

  However, since the lithium-aluminum alloy is pulverized as described above, the pulverized lithium-aluminum alloy falls off from the vicinity of the end portion of the metal lithium-containing layer, for example, when an external impact is applied to the battery. Thus, there is a possibility that the discharge capacity of the battery may be reduced, or the dropped lithium-aluminum alloy powder may come into contact with the positive electrode to reduce the battery voltage and cause a voltage failure.

  Accordingly, in the metallic lithium-containing layer according to the negative electrode, it is preferable that no lithium-aluminum alloy is formed in the vicinity of the end of the surface opposite to the current collector side. Specifically, the area of the region where the lithium-aluminum alloy is formed is preferably 98% or less of the area of the surface opposite to the current collector side of the metal lithium-containing layer according to the negative electrode, More preferably, it is 95% or less. Moreover, it is preferable that the lithium-aluminum alloy is not formed in the part at least 1 mm from the edge in the surface on the opposite side to the collector side of the metallic lithium-containing layer.

  The area ratio of the region where the lithium-aluminum alloy is formed in the surface of the metal lithium-containing layer of the negative electrode according to the battery of the present invention is determined by analyzing using an electron beam microanalyzer (EPMA).

  Examples of the material for the negative electrode current collector according to the battery of the present invention 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 thickness of the metal lithium-containing layer (metal lithium foil or lithium alloy foil) containing lithium that acts as the negative electrode active material has to be reduced, and the battery capacity is reduced. There is a risk of inviting. 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.

  As the positive electrode according to the present invention, for example, as shown in FIG. 2, a sheet-like positive electrode having a configuration in which two positive electrode mixture sheets are laminated via a current collector can be used. In the sheet-like positive electrode having such a structure, for example, the current collector is overlapped by three mm so that the current collector is located a few mm inside of the two positive electrode mixture sheets, and the lengthwise direction that becomes the winding start end portion It can be produced by pressing a portion of 3 to 10 mm from the end. 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 group having a wound structure. The mixture sheet and the current collector may be integrated at the time of winding the electrode group having a wound structure, and there is no particular problem in terms of characteristics even by such a manufacturing method.

  As the positive electrode mixture sheet, 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 rolled using a roll or the like. Then, a pre-sheet can be formed, and a product obtained by drying and pulverizing the sheet can be roll-rolled again to form a sheet shape. Manganese dioxide is used as the positive electrode active material. Examples of the conductive assistant include graphite, carbon black (Ketjen black, etc.) and acetylene black. These may be used alone or in combination of two or more. As the binder, polytetrafluoroethylene (PTFE), rubber binder, or the like can be used. In the case of PTFE, a dispersion type or a powder type may be used, but a dispersion type is particularly preferable.

  In the positive electrode mixture sheet, 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. preferable.

  It is preferable that the positive electrode mixture sheet has a thickness corresponding to 4 to 9% of the inner diameter of the battery outer can per sheet. By providing a positive electrode having a thick positive electrode mixture sheet in this manner, the occupied volume ratio of the positive electrode in the battery is increased to reduce unnecessary gaps in the battery, and the filling amount of the positive electrode active material is increased to increase the battery capacity. Capacitance can be achieved. The specific thickness of each positive electrode mixture sheet varies depending on the size of the battery (the size of the outer diameter of the outer can), but is usually 0.5 to 1.0 mm.

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

In addition, carbon black (especially Ketjen black) whose BET specific surface area is 400-2000 m < ² > / g is used for a conductive support agent, Content of the said conductive support agent in a positive mix sheet is 2.0-4.0 mass. %, And the density of the positive electrode mixture sheet is more preferably 2.2 to 2.7 g / cm ³ , which can also enhance the discharge characteristics at the middle load of the battery. 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.

  Note that 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 the route through the conductive material filled in the mesh is effectively used as well as the route in which the metal part of the mesh current collector is in direct contact with the positive electrode mixture sheet. 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 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 treatment is performed at a high temperature exceeding 200 ° C. when moisture in the positive electrode mixture sheet is removed.

  There is no restriction | limiting in particular as a separator which concerns on the battery of this invention, The separator made from a microporous film and the separator made from a nonwoven fabric employ | adopted for the conventionally known nonaqueous electrolyte primary battery can be used.

  As used herein, the term “microporous film” refers to a film-like body composed of a resin (including so-called sheet-like bodies and plate-like bodies) that includes a large number of minute pores, Ions can pass through the film. For example, fine particles (inorganic fine particles) are blended into a resin and molded into a film-like body, which is stretched uniaxially or biaxially to generate cracks in the vicinity of the fine particles to form pores Etc. can be used. Examples of the resin constituting the microporous film include polyolefins such as polyethylene (PE) and polypropylene (PP); polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyphenylene sulfide (PPS); Can be mentioned. 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.

  In addition, as a nonwoven fabric related to the separator, for example, polyolefin such as polyethylene (PE) and polypropylene (PP); polyester such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyphenylene sulfide (PPS); Those produced by various known production methods can be used.

  The thickness of the separator is preferably 20 to 100 μm, for example.

  In the battery of the present invention, a separator having a microporous film and a nonwoven fabric as constituent elements is preferably used. In the case of a separator having a structure in which a microporous film and a nonwoven fabric are laminated and these are laminated, in the electrode group having a wound structure, the breakage of the separator by the positive electrode active material on the positive electrode surface is suppressed, and a short circuit is prevented. Generation | occurrence | production can be prevented and also the fall of the battery characteristic resulting from omission of the micronized lithium-aluminum alloy in the negative electrode surface can also be prevented.

  That is, if a microporous film and a non-woven fabric are used in combination, even if a microporous film alone causes a crack or the like and a short circuit occurs, a crack or the like does not easily occur and the penetration strength is high. Occurrence of a short circuit can be prevented by the presence of the nonwoven fabric.

  In addition, the finely divided lithium-aluminum alloy on the negative electrode surface may fall off the negative electrode, for example, when an external impact is applied to the battery. Such a dropped lithium-aluminum alloy passes through the separator. If it moves to the positive electrode, it reacts with the positive electrode active material, causing a voltage failure in which the voltage of the battery decreases. If a separator having the microporous film and the nonwoven fabric as constituent elements is used, the microporous film prevents the lithium-aluminum alloy that has fallen off from the negative electrode from moving to the positive electrode, thereby preventing the occurrence of the voltage failure. It is possible to suppress the deterioration of battery characteristics.

  In addition, when the microporous film which concerns on a separator has a crack etc., the movement inhibitory effect to the positive electrode of the lithium-aluminum alloy which fell from the negative electrode will be greatly impaired. If it is a separator having a constituent element, as described above, since the breakthrough of the microporous film is suppressed by the presence of the nonwoven fabric, for example, compared to the case of using a separator composed only of a microporous film, The occurrence of the voltage failure can be suppressed to a higher degree.

  Further, in a separator having a microporous film and a non-woven fabric as constituent elements, when a sudden discharge such as a short circuit occurs in a non-aqueous electrolyte primary battery, the microporous film is configured by heat generated along with this. Shutdown characteristics such as increasing the internal resistance of the battery and ensuring the safety of the battery by melting the resin and closing the pores of the separator can be ensured. In addition, the nonwoven fabric also has an action as an electrolyte solution holding layer for increasing the amount of electrolyte solution held in the separator to further improve the battery capacity.

  In the battery of the present invention, when a separator having a microporous film and a nonwoven fabric as constituent elements is used, it is preferable that the microporous film is disposed so as to be in contact with the negative electrode and the nonwoven fabric is disposed so as to be in contact with the positive electrode. With such an arrangement, the breakage of the microporous film by the positive electrode active material on the surface of the positive electrode can be more highly suppressed by the action of the nonwoven fabric in contact with the positive electrode. The movement of the alloy to the positive electrode can be better prevented.

  When using the separator having the microporous film and the nonwoven fabric as constituent elements, the thickness of the nonwoven fabric is, for example, preferably 10 μm or more, more preferably 20 μm or more, preferably 80 μm or less, more preferably It is 60 μm or less, more preferably 50 μm or less. If the nonwoven fabric is too thin, the effect of preventing the occurrence of a short circuit or voltage failure due to the breakage of the microporous film in the wound electrode group may be reduced. In addition, if the nonwoven fabric is too thin, the amount of electrolyte retained in the separator is also reduced, and the battery capacity improvement effect may be reduced. On the other hand, if the nonwoven fabric is too thick, the battery capacity tends to decrease, and the resistance value of the separator increases, resulting in a decrease in load characteristics or sufficient discharge of electricity for the capacity of the battery. There is a case where a capacity is wasted such that it cannot be performed. When the nonwoven fabric has a thickness of 50 μm or less (that is, 10 μm or more, more preferably 20 μm or more and 50 μm or less) among the above thicknesses, it is particularly preferable because high capacity and load characteristics can be improved.

  Moreover, when using the separator which has the said microporous film and a nonwoven fabric as a component, the thickness of a microporous film becomes like this. Preferably it is 10 micrometers or more, More preferably, it is 20 micrometers or more, Preferably it is 40 micrometers or less. If the microporous film is too thin, a short circuit may easily occur due to the breakage of the microporous film in the wound electrode group. There is a risk of tearing. On the other hand, if the microporous film is too thick, the effect of improving the battery capacity may be reduced, and the resistance value of the separator increases, leading to a decrease in load characteristics or a waste of the above capacity. May occur.

  The width of the separator may be set so that the contact between the positive electrode and the negative electrode can be suppressed, but as described above, it is preferably larger than the width of the positive electrode and more preferably larger than the width of the negative electrode. Furthermore, in the separator having the microporous film and the nonwoven fabric as constituent elements, the width of the microporous film is preferably larger than the width of the negative electrode. When the width of the microporous film according to the separator is larger than the width of the negative electrode and the widest among the microporous film and the nonwoven fabric according to the positive electrode, the negative electrode, and the separator, the width of the electrode body having a wound structure The movement of the lithium-aluminum alloy that has fallen off from the negative electrode can be achieved to a higher degree by folding the microporous film protruding from both ends in the direction toward the winding center of the electrode body.

  On the other hand, in the separator having the microporous film and the non-woven fabric as constituent elements, the non-woven fabric has no effect by widening the microporous film as described above. Therefore, from the viewpoint of reducing the occupied volume of the nonwoven fabric in the battery, it is preferable to make the width of the nonwoven fabric smaller than that of the microporous film in the separator having the microporous film and the nonwoven fabric as constituent elements. It is more preferable that the width is equal to that of the negative electrode.

For example, in the case of a non-aqueous electrolyte primary battery having a positive electrode in which the porosity of the positive electrode mixture sheet is 35 to 50%, since the unevenness of the positive electrode surface in contact with the separator is large, the separator is broken through. However, even in such a case, the occurrence of a short circuit can be suppressed by employing the separator having the microporous film and the nonwoven fabric as constituent elements. In addition, the porosity of a positive mix sheet is calculated | required as follows. For example, when the positive electrode mixture sheet is made of manganese dioxide, ketjen black, and PVDF, the true specific gravity is 4.5 g / cm ³ , 2.0 g / cm ³ , and 2.2 g / cm ^{3, respectively.} The total X (g / cm ³ ) of the calculated mass of each constituent material contained per unit volume of the positive electrode mixture sheet is obtained, and the difference from the actual density Y (g / cm ³ ) of the positive electrode mixture sheet From [(X−Y) / X] × 100, the porosity (%) is obtained.

  Further, the maximum unevenness on the positive electrode surface (that is, the vertical distance between the horizontal line passing through the highest position of the highest convex part and the horizontal line passing through the lowest position of the lowest concave part) is larger than the thickness of the microporous film. Even if it is large (more specifically, for example, 40 μm or more), since the unevenness of the positive electrode surface is large, it is easy for the separator to break through. The separator is also effective for suppressing a short circuit in such a case.

Examples of the electrolyte solution according to the battery of the present invention include a solution prepared by dissolving LiPF ₆ , LiClO ₄ , LiCF ₃ SO _3, etc. as an electrolyte in a non-aqueous solvent such as an organic solvent.

Among the electrolytes described above, LiCF ₃ SO ₃ is preferably used from the viewpoint of further improving battery safety. When metallic lithium is used for the negative electrode and LiCF ₃ SO ₃ is used for the solute, fluorine ionized from LiCF ₃ SO ₃ reacts with active lithium during storage of the battery, and the negative electrode surface is in a passive state. Since a certain lithium fluoride film is formed and the internal resistance of the battery is increased, the discharge characteristics are deteriorated. However, in the battery of the present invention, a part of the negative electrode has a lithium-aluminum alloy, and this lithium-aluminum alloy has lower activity than lithium alone, so that fluorine ions and lithium present during storage -It is hard to react with an aluminum alloy, the production | generation of the passive state film in the negative electrode surface is suppressed, and the fall of a discharge characteristic can be suppressed.

  Since the cylindrical non-aqueous electrolyte primary battery of the present invention has good heavy load pulse discharge characteristics, taking advantage of these characteristics, it is repeatedly required to discharge in a very short time, such as a gas meter shut-off valve or wireless communication. For example, it can be preferably used in various applications to which a conventionally known cylindrical non-aqueous electrolyte primary battery is applied.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention. In addition, "%" used in a present Example is a mass reference | standard (mass%) unless there is particular notice.

Example 1
For the cylindrical non-aqueous electrolyte primary battery of Example 1, “preparation of positive electrode”, “preparation of negative electrode”, “preparation of electrode winding body”, “battery assembly”, “post-treatment (preliminary discharge, aging)” Will be described in the order.

<Preparation 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 600 m ² / g: 3% and manganese dioxide (manufactured by Tosoh Corporation): 92% were mixed by a dry method using a planetary mixer for 5 minutes, 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. At this time, the preliminary sheet was pulverized until it became twice or more the original apparent volume. Most of the particle size after pulverization was 1 mm or less, and PTFE added as a binder was also cut into fibers having a length of 1 mm or less. The pulverized material was formed into a sheet again by a roll. The interval between the rolls was adjusted to 0.6 ± 0.05 mm, and a positive electrode mixture sheet was obtained by forming a sheet under the conditions of roll temperature: 125 ± 10 ° C., press pressure: 7 ton / cm, and rotation speed: 10 rpm. The obtained positive electrode mixture sheet has a thickness of 1.0 mm and corresponds to 5.9% of the inner diameter of the outer can. Moreover, the density of the positive mix sheet was 2.5 g / cm < ³ >, and the porosity calculated | required by the said method was 42%. This positive electrode mixture sheet is cut into a positive electrode mixture sheet (positive electrode mixture sheet 43 in FIG. 2) having a width of 38 mm and a length of 51 mm, and an outer periphery having a width of 38 mm and a length of 62 mm. The positive electrode mixture sheet (positive electrode mixture sheet 41 in FIG. 2) was obtained.

As the positive electrode current collector, an expanded metal made of stainless steel (SUS316) was used. The expanded metal was cut into 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 center 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 part of the two positive electrode mixture sheets from the end where both are aligned, so that the three parties are integrated. did. Thereafter, the two positive electrode mixture sheets and the positive electrode current collector were integrated with hot air at 250 ± 10 ° C. for 6 hours to obtain a sheet-like positive electrode having a width of 38 mm.

<Preparation of negative electrode (negative electrode precursor)>
The negative electrode has a metal lithium foil having a width of 37 mm, a length of 192 mm, and a thickness of 0.22 mm on a copper foil (negative electrode current collector) having a width of 38 mm, a length of 200 mm, and a thickness of 15 μm. On top of that, an aluminum foil having a width of 35 mm, a length of 192 mm and a thickness of 6 μm was arranged by arranging one end thereof (one end in the length direction). First, the metal lithium foil is disposed on the copper foil, the aluminum foil is disposed on the metal lithium foil, and a sheet-shaped negative electrode (sheet-shaped negative electrode precursor before lithium-aluminum alloy formation, Hereinafter, for convenience, a “sheet-like negative electrode”) was prepared.

<Preparation of wound electrode group>
Width: 45 mm, length: 170 mm, thickness: 20 μm microporous polyethylene film and width: 42 mm, length: 170 mm, thickness: 20 μm non-woven fabric are laminated together, and the length direction of the microporous polyethylene film A separator was manufactured by heat welding at a position 65 mm from one end of the film.

  A separator was pasted on the copper foil of the sheet-like negative electrode via an adhesive tape. In addition, when affixing a separator to a negative electrode, the nonwoven fabric surface was made into the positive electrode side, and the heat welding part of the microporous film of a separator and a nonwoven fabric was included in the adhesion part with an adhesive tape. Next, centering on the heat-welded part between the microporous film of the separator and the nonwoven fabric, 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.

<Battery assembly>
An assembly process of the cylindrical non-aqueous electrolyte primary battery will be described with reference to FIG. A polypropylene insulating plate 14 having a thickness of 0.2 mm is inserted into an inner bottom portion 2a of a bottomed cylindrical outer can 2 made of nickel-plated iron cans, and an electrode group 3 having a wound structure is formed thereon. The lead body 15 was inserted with the posture facing upward. The negative electrode lead body 16 of the electrode group 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 body 9 after inserting the insulating plate 10. At this point, the insulation resistance was measured and it was confirmed that there was no short circuit.

As the electrolyte, a non-aqueous solution prepared by dissolving LiClO ₄ at a concentration of 0.5 mol / l in a mixed solvent of propylene carbonate and dimethoxyethane (volume ratio of 1: 2) was prepared, and this was used as an outer can. 3.5 ml was injected into 2. 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 lid plate 7 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 lid plate 7 are welded by laser welding. 2 openings were sealed.

<Post-processing (preliminary discharge, aging)>
The sealed battery was pre-discharged with a resistance of 1Ω for 30 seconds, stored at 70 ° C. for 6 hours, then subjected to a secondary pre-discharge with a constant resistance of 1Ω for 1 minute, and lithium-aluminum on the separator-side surface of the sheet-like negative electrode. An alloy was formed. 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 non-cylindrical shape having an outer diameter of 17.0 mm and a total height of 45.0 mm A water electrolyte primary battery was obtained. The ratio of the negative electrode capacity to the positive electrode capacity of this battery was 1.00.

Comparative Example 1
Width: 37 mm, length: 200 mm, thickness: on a 15 μm copper foil (negative electrode current collector), width: 37 mm, length: 71 mm, thickness: 0.22 mm metal lithium foil, width: 37 mm, length : 98 mm, thickness: 0.22 mm metal lithium foil is arranged, and further, on it, width: 30 mm, length: 71 mm, thickness: 6 μm aluminum foil, width: 30 mm, length: 98 mm, thickness : 6 μm aluminum foil was arranged. First, the two metal lithium foils are arranged on the copper foil in a state of being separated from each other, and the two aluminum foils are respectively arranged on the two metal lithium foils to form a sheet-like negative electrode. Produced.

  A cylindrical nonaqueous electrolyte primary battery was produced in the same manner as in Example 1 except that this sheet-like negative electrode was used.

  The cylindrical nonaqueous electrolyte primary batteries of Example 1 and Comparative Example 1 were subjected to the following discharge capacity measurement and pulse discharge characteristic evaluation. These results are shown in Table 1 together with the structure of the negative electrode of each battery. Also, among the cylindrical non-aqueous electrolyte primary batteries of Example 1 and Comparative Example 1, those which were not used for the discharge capacity measurement and pulse discharge characteristic evaluation were disassembled, the negative electrode was taken out, and the metal lithium-containing layer Of the area of the surface opposite to the current collector, the area of the region where the lithium-aluminum alloy was formed was determined by EPMA. The results are also shown in Table 1.

<Discharge capacity measurement>
Each cylindrical non-aqueous electrolyte primary battery was continuously discharged at 23 ° C. with a current value of 40 mA, and the discharge capacity until the battery voltage reached 2.0 V was measured. In addition, the number of samples of each battery was set to five, and the average value was made into the discharge capacity of the battery of Example 1 and Comparative Example 1.

<Pulse discharge characteristics>
Each cylindrical non-aqueous electrolyte primary battery was in a state in which a current of 2000 mAh corresponding to 80% of the theoretical capacity was discharged, and the voltage after pulse discharge for 1300 ms at −30 ° C. at a current value of 500 mA was obtained. It was measured.

  “Number of metal lithium-containing layers” in Table 1 represents the number of metal lithium-containing layers provided on one side of the negative electrode current collector, and “1” is only one continuous layer. “2” means two layers that are separated from each other. In Table 1, “the ratio of the area covered by the metal lithium-containing layer” means the ratio of the area of the region covered with the metal lithium-containing layer in the area of one surface of the current collector. The “area ratio of the alloy formation region” means the ratio of the area of the region where the lithium-aluminum alloy is formed in the area of the surface of the metallic lithium-containing layer opposite to the current collector.

  As shown in Table 1, it has a metallic lithium-containing layer composed of only one continuous layer on one side of the current collector, and among the formation surfaces of the metallic lithium-containing layer in the current collector, metallic lithium The cylindrical non-aqueous electrolyte primary battery of Example 1 in which the area of the region covered with the containing layer is appropriate and the lithium-aluminum alloy is formed on the surface of the metallic lithium-containing layer is the current collector. Comparative example in which the area of the region covered with the metal lithium-containing layer is not appropriate among the formation surfaces of the metal lithium-containing layer in the current collector, having two metal lithium-containing layers formed apart on one side Compared with the battery No. 1, the voltage after the pulse discharge characteristics evaluation is high, and the heavy load pulse discharge characteristics are excellent. In addition, the battery of Example 1 was able to suppress the winding deviation when forming the electrode group having a wound structure, and the productivity was good as compared with the battery of Comparative Example 1.

DESCRIPTION OF SYMBOLS 1 Cylindrical nonaqueous electrolyte primary battery 2 Exterior can 3 Electrode group of winding structure 4 Positive electrode 5 Negative electrode 6 Separator 41, 42 Positive electrode mixture sheet 43 Positive electrode current collector 51 Metal lithium content layer 52 Negative electrode current collector

Claims (2)

A cylindrical non-aqueous electrolyte primary battery having an electrode group having a wound structure in which a positive electrode containing manganese dioxide and a negative electrode are wound in a spiral shape through a separator,
The negative electrode, on one surface of a current collector made of a foil, has a metal lithium-containing layer consisting only of a layer consisting of continuous single foil,
The metal lithium-containing layer covers 85% or more of the area of the formation surface of the metal lithium-containing layer in the current collector,
A cylindrical non-aqueous electrolyte primary battery, wherein a lithium-aluminum alloy is formed on at least a part of the surface of the metallic lithium-containing layer opposite to the current collector.   2. The cylindrical non-aqueous electrolyte primary according to claim 1, wherein the lithium-aluminum alloy is formed in a region of 85 to 98% of the surface area of the metallic lithium-containing layer opposite to the current collector side. 3. battery.

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