JP2005347161A - Battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery preventing the occurrence of a short circuit even in a state of high temperature and also heightening energy density. <P>SOLUTION: A positive electrode 21 and a negative electrode 22 are laminated through a separator 23 and electrolyte. The electrolyte is in a gelatinous state retaining the electrolyte in high molecular compound. An attachment part of a positive electrode lead 11, ends 21C and 22D and end facing ranges 21E and 22E are covered by a covering material 24 consisting of 5 μm or more of polyethylene telephthalate, polyphenylene sulfide or polyimide. Thus an electrical contact of the attachment part of the positive electrode lead 11 and the end 21C with the end facing range 22E or an electrical contact between the end 22D and the end facing range 21E are prevented even in the high temperature state. Furthermore, the thickness of the covering material 24 can be made thin and energy density can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery including an electrode winding body in which a positive electrode and a negative electrode are stacked and wound via an electrolyte inside a film-shaped exterior member, and more particularly, to a battery including a covering material on an end portion of an electrode or the like. .

  As mobile devices such as mobile phones, notebook computers, PDAs (Personal Digital Assistants) and digital cameras become more popular, the demand for smaller, lighter and thinner batteries for these power sources has been increasing year by year. ing. As countermeasures against such demands, it has been proposed to use inorganic / organic complete solid electrolytes or semi-solid electrolytes (gel electrolytes) made of polymer gels. This eliminates the problem of electrolyte leakage and eliminates the need to use a hard cell for the exterior material, thereby making it possible to achieve further reductions in size and weight and thickness. In addition, the degree of design freedom is improved.

  Electricity collection in a battery that does not use a hard cell as an exterior material cannot be performed by itself as in the case of a hard cell. Therefore, it is necessary to provide a current collecting lead so as to be exposed to the outside. In many cases, such a lead is generally welded to an uncoated portion where an active material layer is not coated at the end portions of the positive electrode and the negative electrode.

  However, when a lead or an uncoated part is provided in this way, a protrusion such as a cutting burr or a warp generated at a cut end mechanically cut by a mold or the like causes the other during the manufacture or use of a battery. There was a problem that a short circuit would occur due to contact with the electrode.

Therefore, a short circuit has been prevented by covering a lead provided on the positive electrode or the negative electrode or a cut end portion of an uncoated portion with a polypropylene insulating tape or the like (see, for example, Patent Document 1).
JP 2001-266946 A

  By the way, with the recent improvement in portability of portable devices, they have been carried in various environments, for example, in places exposed to high temperatures such as in a car under the sun or in front of a fan heater outlet. The number of cases left unattended has increased.

  In this way, when the battery is exposed to a very high temperature condition even temporarily, the material of the insulating tape described above is the shrinkage caused by heat in the polypropylene as in the conventional case, and the coated lead or uncoated Since the coated portion is exposed, a short circuit may occur due to a protruding portion such as a cutting burr or warping of the cut end. As a result, there is a problem that the self-discharge becomes large or the output cannot be taken out at all.

  In addition, in the conventional insulating tape made of polypropylene, the thickness cannot be reduced, and the energy density cannot be further increased.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a battery capable of preventing the occurrence of a short circuit and increasing the capacity even under high temperature conditions. is there.

  The battery of the present invention comprises an electrode winding body in which a positive electrode and a negative electrode are laminated and wound via an electrolyte, and is provided inside a film-like exterior member, and has a counter electrode in the winding direction of the positive electrode and the negative electrode. A covering material covering at least one of the opposite end and the counter electrode region facing the end, the covering being at least one of the group consisting of polyethylene terephthalate, polyphenylene sulfide and polyimide; It contains seeds and has a thickness of 5 μm or more.

  According to the battery of the present invention, the end facing the counter electrode in the winding direction of the positive electrode and the negative electrode, or the region of the counter electrode facing this end includes polyethylene terephthalate, polyphenylene sulfide, or polyimide, and the thickness is 5 μm or more. Since it was made to cover with the covering material, it is possible to prevent a short circuit under the manufacturing process and high temperature conditions. Further, since the thickness of the covering material can be reduced, the energy density can also be increased.

  Further, if the attachment portion of the positive electrode lead or the attachment portion of the negative electrode lead is covered with a covering material, electrical contact between these end portions and the counter electrode of the electrode to which these are attached can be prevented. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 shows the configuration of the secondary battery according to the first embodiment of the present invention. The secondary battery is, for example, a lithium ion secondary battery, and has a configuration in which the electrode winding body 20 to which the positive electrode lead 11 and the negative electrode lead 12 are attached is housed in a film-shaped exterior member 31. .

  The positive electrode lead 11 and the negative electrode lead 12 are for taking out the electromotive force generated in the electrode winding body 20 to the outside, for example, each having a strip shape, and extending from the inside of the exterior member 31 to the outside, for example, in the same direction. Has been derived. The positive electrode lead 11 is made of a metal material such as aluminum (Al), and the negative electrode lead 12 is made of a metal material such as nickel (Ni).

  The exterior member 31 is made of, for example, a rectangular aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. For example, each outer edge portion of the exterior member 31 is in close contact with each other by fusion bonding or an adhesive.

  An adhesion film 32 between the exterior member 31 and the positive electrode lead 11 and the negative electrode lead 12 for improving the adhesion between the positive electrode lead 11 and the negative electrode lead 12 and the inside of the exterior member 31 and preventing intrusion of outside air. Has been inserted. The adhesion film 32 is made of a material having adhesion to the positive electrode lead 11 and the negative electrode lead 12. For example, when the positive electrode lead 11 and the negative electrode lead 12 are made of the metal material described above, a polyolefin such as polyethylene is used. It is preferable to be comprised with resin.

  FIG. 2 shows a cross-sectional structure taken along line II of the electrode winding body 20 shown in FIG. The electrode winding body 20 is obtained by laminating and winding a positive electrode 21 and a negative electrode 22 via an electrolyte and a separator 23, and the outermost peripheral portion is protected by a protective tape (not shown). The electrolyte is provided between the positive electrode 21 and the separator 23, and between the negative electrode 22 and the separator 23, but is omitted in FIG.

  The positive electrode 21 includes, for example, a positive electrode current collector 21A and a positive electrode active material layer 21B provided on both surfaces or one surface of the positive electrode current collector 21A. In the positive electrode current collector 21A, for example, a region where the positive electrode active material layer 21B is not provided is formed on the winding center side and the winding outer peripheral side, and the exposed region is formed, for example, in the exposed region on the winding center side. A positive electrode lead 11 is attached. The positive electrode current collector 21A is made of, for example, a metal foil such as an aluminum foil that has good conductivity, is light and inexpensive, and has good workability.

  The positive electrode active material layer 21B includes, for example, one or more of positive electrode materials capable of inserting and extracting lithium as a positive electrode active material (hereinafter referred to as positive electrode materials capable of inserting and extracting lithium). If necessary, a conductive agent such as a carbon material and a binder such as polyvinylidene fluoride may be included. As the positive electrode material capable of inserting and extracting lithium, for example, a lithium composite oxide containing lithium and a transition metal or a lithium phosphate compound is preferable. This is because they can generate a high voltage and have a high density, so that the capacity can be increased.

  The negative electrode 22 includes, for example, a negative electrode current collector 22A and a negative electrode active material layer 22B provided on both surfaces or one surface of the negative electrode current collector 22A, as with the positive electrode 21. The negative electrode current collector 22A has, for example, an exposed region where the negative electrode active material layer 22B is not provided on the winding center side and the winding outer periphery side. For example, in the exposed region on the winding center side, the negative electrode lead 12 is attached. The negative electrode current collector 22A is made of, for example, a metal foil such as a copper foil having good conductivity, light weight, low cost, and good workability.

  The negative electrode active material layer 22B includes, for example, one or more of negative electrode materials capable of inserting and extracting lithium as a negative electrode active material (hereinafter referred to as negative electrode materials capable of inserting and extracting lithium). And a binder such as polyvinylidene fluoride may be included as necessary.

  Examples of the negative electrode material capable of inserting and extracting lithium include carbon materials such as graphite, non-graphitizable carbon, and graphitizable carbon. Moreover, the simple substance, alloy, or compound of the metal element or metalloid element which can form an alloy with lithium is also mentioned.

  An end portion 21C on the winding center side of the positive electrode current collector 21A and an end portion 22D on the outer periphery side of the winding in the negative electrode current collector 22A are opposed to the counter electrode, for example, via a separator 23. The end 21D on the winding outer periphery side of the body 21A and the end 22C on the winding center side of the negative electrode current collector 22A are opposed to the same electrode, for example, via the separator 23 or not. Yes.

  Of these ends, the end 21C and the end 22D are preferably covered with a covering material 24, for example. This is to prevent the separator 23 from being damaged and short-circuited with the counter electrode due to protrusions such as cutting burrs or warping formed on the end portions 21C and 22D.

  On the other hand, the end 21D and the end 22C may be covered by the covering material 24, but may not be covered. This is because the same electrodes are opposed to these end portions 21D and 22C, so that even if they come into contact with each other and a short circuit occurs, the electromotive capacity of the battery is hardly affected.

  The covering material 24 is preferably an insulating material having high mechanical strength. For example, a resin such as polyethylene terephthalate, polyphenylene sulfide, polyimide, nylon, polytetrafluoroethylene, cellulose triacetate, polystyrene, polycarbonate, or glass cloth. It is preferable to comprise. Of these, polyethylene terephthalate, polyphenylene sulfide, and polyimide are preferable. This is because, even under high temperature conditions, it is difficult to shrink, and exposure of protrusions such as cutting burrs or warping can be suppressed. Moreover, it is because the thickness of the coating | covering material 24 can be made thin and an energy density can be made high. Any one of these coating materials 24 may be used as a single layer, or a plurality of types may be used in a stacked manner.

  The thickness of the covering material 24 is preferably 5 μm or more, more preferably 5 μm or more and 50 μm or less, still more preferably 5 μm or more and less than 20 μm, and particularly preferably 5 μm or more and less than 12 μm. If it is thin, it will be damaged by external pressure at the time of manufacturing and the like, and projections such as cutting burrs or warping will be exposed, and if it is thick, it will spread between the electrodes and hinder electrode reaction.

  Moreover, it is preferable that the coating | covering material 24 has covered the surface of the attachment part of the positive electrode lead 11 with the edge part 21C. This is because the attachment portion of the positive electrode lead 11 is opposed to the negative electrode 22 with the separator 23 interposed therebetween, and the positive electrode lead 11 has protrusions such as cutting burrs or warping.

  In addition, although the attachment part of the negative electrode lead 12 may be covered with the coating | covering material 24, it does not need to be covered. This is because the negative electrode 22 faces the mounting portion.

  Any separator 23 may be used as long as it is electrically stable and chemically stable with respect to the positive electrode active material, the negative electrode active material or the solvent and does not have electrical conductivity. Examples thereof include microporous polypropylene.

  The electrolyte is formed on the surfaces of the positive electrode active material layer 21B and the negative electrode active material layer 22B. The electrolyte salt, a solvent that dissolves the electrolyte salt, and a polymer compound that serves as a holding body that holds the electrolyte salt and the solvent. And a so-called gel.

Examples of the electrolyte salt include lithium salts such as LiClO ₄ , LiPF ₆ , LiBF ₄ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , or LiAsF ₆ .

  Examples of the solvent include non-aqueous solvents such as ethylene carbonate, dimethyl carbonate, and propylene carbonate.

  The polymer compound is not particularly limited as long as it absorbs a solvent and gels, and examples thereof include fluorine-based polymer compounds such as polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropropylene.

  The secondary battery having such a configuration can be manufactured, for example, as follows.

  First, for example, a positive electrode active material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, which is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a positive electrode mixture slurry. Next, the positive electrode mixture slurry is applied to both surfaces or one surface of the positive electrode current collector 21A, dried, and compression-molded to form the positive electrode active material layer 21B, whereby the positive electrode 21 is manufactured. Subsequently, for example, the positive electrode lead 11 is joined to the positive electrode current collector 21A by, for example, ultrasonic welding or spot welding. After that, a solvent, an electrolyte salt, and a polymer compound are mixed using a solvent, and this mixed solution is applied on the positive electrode active material layer 21B, that is, on both sides or one side of the positive electrode 21 to volatilize the solvent. To form an electrolyte.

  Further, for example, a negative electrode active material and a binder are mixed to prepare a negative electrode mixture, which is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a negative electrode mixture slurry. Next, the negative electrode mixture slurry is applied to, for example, both surfaces or one surface of the negative electrode current collector 22A, dried, and compression molded to form the negative electrode active material layer 22B, whereby the negative electrode 22 is fabricated. Subsequently, the negative electrode lead 12 is joined to the negative electrode current collector 22A by, for example, ultrasonic welding or spot welding, and the electrolyte is formed on the negative electrode active material layer 22B, that is, on both sides or one side of the negative electrode 22 in the same manner as the positive electrode 21. Form.

  Subsequently, the covering material 24 is bonded so as to cover the end portions 21C and 22D and the attachment portion of the positive electrode lead 11. After that, for example, the negative electrode 22 formed with the electrolyte, the separator 23, the positive electrode 21 formed with the electrolyte, and the separator 23 are laminated and wound in this order, and a protective tape is adhered to the outermost peripheral portion to form the electrode wound body 20 To do. At this time, it is preferable to press and process into a flat shape. This is because the electrical contact state between the electrolyte and the positive electrode 21 or the negative electrode 22 can be ensured. At this time, in the present embodiment, since the end portions 21C and 22D and the attachment portion of the positive electrode lead 11 are covered with the covering material 24, an internal short circuit due to the breakage of the separator 23 is prevented.

  After the electrode winding body 20 is formed, the electrode winding body 20 is sandwiched between the exterior members 31, and the outer edge portions of the exterior member 31 are brought into close contact by thermal fusion or the like and sealed. At that time, an adhesive film 32 is inserted between the positive electrode lead 11, the negative electrode lead 12, and the exterior member 31. Thereby, the secondary battery shown in FIG. 1 is completed.

  In this secondary battery, when charged, lithium ions are released from the positive electrode 21 and inserted in the negative electrode 22 through the electrolyte. When discharging is performed, for example, lithium ions are released from the negative electrode 22 and are inserted in the positive electrode 21 through the electrolyte. At this time, since the attachment portions of the end portions 21C and 22D and the positive electrode lead 11 are covered with the covering material 24, the end portions of the end portions 21C and 22D and the positive electrode lead 11, for example, even at the time of manufacturing or under a high temperature condition. The occurrence of an internal short circuit due to a protrusion such as a cutting burr or warping formed on the substrate is prevented.

  As described above, according to the secondary battery of the present embodiment, the covering material 24 including polyethylene terephthalate, polyphenylene sulfide, or polyimide and having a thickness of 5 μm or more is provided at the end portions 21C and 22D facing the counter electrode. Therefore, it is possible to prevent the occurrence of a short circuit under the manufacturing process and high temperature conditions. Moreover, since the thickness of the coating | covering material 24 can be made thin, an energy density can also be made high.

  Further, if the attachment portion of the positive electrode lead 11 is covered with the covering material 24, electrical contact between this portion and the negative electrode 22 can be prevented.

[Second Embodiment]
FIG. 3 shows a cross-sectional configuration of the electrode winding body 20 of the secondary battery according to the second embodiment of the present invention. Except that the area covered with the covering material 24 is different, the rest has the same configuration as that of the first embodiment. Therefore, in the present embodiment, referring to FIG. 1, the same components as those in the first embodiment are denoted by the same reference numerals, and the description of the same parts is omitted. In FIG. 3, the electrolyte is omitted.

  The positive electrode 21 has, for example, an end facing region 21E that faces the end 22D of the negative electrode 22 via the separator 23, and an end facing region 22F that faces the end 21D of the positive electrode 21. 22 includes, for example, an end facing region 22E that faces the end 21C of the positive electrode 21 via the separator 23, and an end facing region 22F that faces the end 22C of the negative electrode 22 via the separator 23. .

  Of these, the end-facing regions 21E and 22E are covered with the covering material 24 described in the first embodiment, for example. This is to prevent electrical short contact between the protrusions such as cutting burrs or warps formed on the end portions 22D and 21C and the end facing regions 21E and 22E, thereby preventing a short circuit. On the other hand, the end facing regions 21F and 22F facing the same electrode may be covered with the covering material 24, but may not be covered.

  The secondary battery can be manufactured in the same manner as in the first embodiment except that the covering material 24 is bonded to the end facing regions 21E and 22E. Since the positions of the end portions 21C and 22D may be shifted when the electrode winding body 20 is pressed, it is preferable to widen the region covered with the covering material 24 in consideration of these shifts.

  As described above, according to the secondary battery of the present embodiment, the end facing regions 21E and 22E are covered with the covering material 24. Therefore, as in the first embodiment, a short circuit occurs under the manufacturing process and high temperature conditions. Can be prevented.

[Third Embodiment]
FIG. 4 illustrates a cross-sectional configuration of the electrode winding body 20 of the secondary battery according to the third embodiment of the present invention. Except that the region covered with the covering material 24 is the end 21C, 22D, the end facing region 21E, 22E, and the attachment portion of the positive electrode lead 11, the rest is the same as in the first and second embodiments. It can be manufactured in the same manner. Therefore, in the present embodiment, referring to FIG. 1, the same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and description of the same parts is omitted. To do. In FIG. 4, the electrolyte is omitted.

  In FIG. 4, the end portions 21 </ b> C and 22 </ b> D, the end facing regions 21 </ b> E and 22 </ b> E, and the attachment portion of the positive electrode lead 11 are all covered with the covering material 24. Or any one of the end facing regions 22E, or any one of the end 22D or the end facing region 21E.

  Further, specific embodiments of the present invention will be described in detail.

  The secondary battery described in the embodiment was manufactured. At that time, the position covered with the covering material 24 was set to the position shown in FIG.

First, 85 parts by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 5 parts by mass of artificial graphite powder as a conductive agent, and 5 parts by mass of carbon black are sufficiently mixed, and then N-methyl-2-pyrrolidone. A positive electrode mixture slurry was prepared by adding 5 parts by mass of polyvinylidene fluoride, which is a binder, dissolved in a solid content. The positive electrode mixture slurry was intermittently applied to both surfaces of a positive electrode current collector 21A made of a strip-shaped aluminum foil having a thickness of 20 μm and dried on a double-sided surface. The material layer 21B was formed, and the positive electrode raw material was produced. This positive electrode original fabric was cut at an uncoated portion, and after preparing the positive electrode 21, it was wound up and dried in a vacuum.

  The wound positive electrode 21 is unwound, and a positive electrode lead 11 having a width of 5 mm, a length of 70 mm, and a thickness of 0.07 mm is joined by ultrasonic welding to an exposed area where the positive electrode active material layer 21B on the winding center side is not provided. did. At that time, one end of the positive electrode lead 11 protrudes from the end parallel to the winding direction of the positive electrode 21 by 15 mm or more.

  Further, as a negative electrode active material, polyvinylidene fluoride, which is a binder dissolved in N-methyl-2-pyrrolidone, is mixed in 90 parts by mass of natural graphite (interlayer distance: 0.335 nm) having a particle size of 5 μm or more and 30 μm or less. Was added to 10 parts by mass to prepare a negative electrode mixture slurry. The negative electrode mixture slurry was intermittently applied to both sides of the negative electrode current collector 22A made of a strip-shaped copper foil having a thickness of 15 μm, dried and then rolled by a roller press machine. The layer 22B was formed, and a negative electrode original fabric was produced. The negative electrode original fabric was cut at an uncoated portion to prepare a negative electrode 22 and then wound in a vacuum.

  The wound negative electrode 22 is unwound, and the negative electrode lead 12 having a width of 4 mm, a length of 70 mm, and a thickness of 0.07 mm is joined by ultrasonic welding to the exposed region where the negative electrode active material layer 22B on the winding center side is not provided. did. At that time, one end of the negative electrode lead 12 protruded from the end parallel to the winding direction of the negative electrode 22 by 15 mm or more.

  Next, polyvinylidene fluoride is added to dimethyl carbonate, which is a solvent, so that the solid content is 20 parts by mass. To this, 8 parts by mass of a lithium salt and 72 parts by mass of a solvent obtained by mixing ethylene carbonate and propylene carbonate are added. The mixture was stirred while keeping the temperature to prepare a mixed solution for the electrolyte.

  This mixed solution is applied to the surfaces of the positive electrode active material layer 21B and the negative electrode active material layer 22B using a hot melt applicator and dried to make the mixed solution into the voids in the positive electrode active material layer 21B and the negative electrode active material layer 22B. While impregnating, dimethyl carbonate was volatilized to form a gel electrolyte.

  Next, as shown in FIG. 4, a covering material 24 having a width of 19 mm was adhered to the end portions 21C and 22D and the end facing regions 21E and 22E with an adhesive. At that time, the covering material 24 was adhered to the end portion 21 </ b> C so as to cover the positive electrode lead 11, and the positive electrode lead 11 was covered to about 2 mm from the end portion parallel to the winding direction of the positive electrode 21. The material of the covering material 24 was polyethylene terephthalate, polyphenylene sulfide, or polyimide, and the thickness was changed within the range of 5 μm to 50 μm as shown in Table 1. The adhesive has a thickness of 10 μm.

  Next, after laminating the positive electrode 21 and the negative electrode 22 via the separator 23, the electrode winding body 20 is wound by pressing in the longitudinal direction to form a flat shape and fixing the winding end portion using an adhesive tape. Produced. This electrode winding body 20 was accommodated in the exterior member 31 and sealed in a vacuum. Through the above steps, the secondary battery shown in FIGS. 1 and 4 was obtained.

  As a comparative example to this example, a secondary battery was fabricated in the same manner as in the example except that the thickness of the covering material 24 was 3 μm or 4 μm as shown in Table 1. Further, a secondary battery was fabricated in the same manner as in the example except that polypropylene was used as the covering material 24 and the thickness was changed within the range of 3 μm to 50 μm as shown in Table 2.

  The incidence of internal short circuit was determined for each of the 100 secondary batteries obtained in Examples and Comparative Examples. The obtained results are shown in Tables 1 and 2.

  Moreover, about the secondary battery in which the incidence rate of the internal short circuit at the time of manufacture was 1% or less, each 10 pieces which are not internally short-circuited were prepared, and the incidence rate of the short circuit under high temperature conditions was calculated | required. The obtained results are shown in Tables 3 and 4.

  The occurrence rate of short circuit under high temperature conditions was determined as follows, assuming that the battery was left for 10 minutes before the fan heater outlet. First, a constant current constant voltage charge is performed for 4.5 hours with a current value of 1 A at an upper limit of 4.2 V, these batteries are placed in a thermostatic bath, the temperature increase rate is set to 5 ° C./min, and the temperature is increased. When the temperature reached 160 ° C., the temperature was kept constant for 10 minutes. At this time, the occurrence rate of the short circuit was determined from the one in which the open circuit voltage was lowered. Further, the behavior of the change in the open circuit voltage at this time is shown in FIG. 5 when the covering material 24 has a thickness of 12 μm. Since the behavior of polyphenylene sulfide and polyimide is the same as that of polyethylene terephthalate, it is omitted here.

  As can be seen from Tables 1 and 2, the battery using the covering material 24 made of polyethylene terephthalate, polyphenylene sulfide or polyimide having a thickness of 5 μm or more and 50 μm or less than the battery using the covering material 24 made of polypropylene. The occurrence rate of short circuit was low even in a thin region, for example, in the range of 5 μm to 12 μm.

  In addition, as can be seen from Tables 3 and 4 and FIG. 5, in the battery using the coating material 24 made of polypropylene, the open circuit voltage decreased from around 155 ° C. and short circuit started to occur, whereas polyethylene terephthalate The battery using an insulating tape made of polyphenylene sulfide or polyimide did not show a decrease in open circuit voltage even at 160 ° C., and no short circuit occurred.

  That is, at least one of the end 21C and the attachment portion of the positive electrode lead 11, and the end facing region 22E, and at least one of the end 22D and the end facing region 21E are made of polyethylene terephthalate having a thickness of 5 μm or more, It was found that short circuiting can be prevented even during the manufacturing process or under high temperature conditions by covering with a covering material 24 made of polyphenylene sulfide or polyimide.

  It has also been found that if the coating material 24 made of polyethylene terephthalate, polyphenylene sulfide or polyimide is used, the thickness of the coating material 24 can be reduced and the energy density can be increased.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, a case where a gel electrolyte in which an electrolytic solution is held in a polymer compound is used as the electrolyte has been described. However, instead of the gel electrolyte, another electrolyte is used. It may be. Examples of other electrolytes include solid electrolytes having ionic conductivity, a mixture of a solid electrolyte and an electrolytic solution, and a mixture of a solid electrolyte and a gel electrolyte.

  As the solid electrolyte, for example, an organic solid electrolyte in which an electrolyte salt is dispersed in a polymer compound having ion conductivity, or an inorganic solid electrolyte made of ion conductive glass or ionic crystal can be used. As the inorganic solid electrolyte, lithium nitride or lithium iodide can be used.

  Moreover, in the said embodiment and Example, although the battery provided with the winding structure inside the exterior member 31 which consists of a laminate film was demonstrated, as long as this invention is a battery provided with the winding structure, all apply. can do. Moreover, not only a secondary battery but a primary battery is applicable.

  Further, in the above-described embodiment and examples, the case where the winding center side end portion 21C of the positive electrode 21 and the winding outer peripheral side end portion 22D of the negative electrode 22 are opposed to the counter electrode are described. Only one of them may face the counter electrode, or the winding outer peripheral end 21D of the positive electrode 21 or the winding center side end 22C of the negative electrode 22 may face the counter electrode. In this case, it is only necessary to cover at least one of the end portions 21C, 21D, 22C, 22D and the region of the counter electrode facing these with a covering material.

  Furthermore, in the above-described embodiments and examples, the material constituting each constituent element such as the positive electrode 21, the negative electrode 22, or the electrolyte has been described as an example, but other materials may be used. In addition, although the so-called lithium ion secondary battery has been described in the above embodiments and examples, the present invention can be similarly applied to a battery using other electrode reactions. Other batteries include, for example, so-called lithium metal batteries that use lithium precipitation / dissolution in the negative electrode, or lithium storage / release and precipitation / dissolution in the negative electrode. It is a battery represented by the sum of a component and a capacity component by precipitation / dissolution. Further, other light metals other than lithium as the electrode reactant, for example, other group 1 elements in the long-period periodic table such as sodium (Na) or potassium (K), or long-period type such as magnesium or calcium (Ca) Examples include batteries using Group 2 elements in the periodic table or other light metals such as aluminum.

1 is an exploded perspective view of a secondary battery according to an embodiment of the present invention. It is sectional drawing along the II line of the electrode winding body shown in FIG. FIG. 3 is another cross-sectional view taken along line II of the electrode winding body illustrated in FIG. 1. FIG. 3 is another cross-sectional view taken along line II of the electrode winding body illustrated in FIG. 1. It is a figure showing the behavior of the open circuit voltage in the high temperature test done in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Positive electrode lead, 12 ... Negative electrode lead, 20 ... Electrode winding body, 21 ... Positive electrode, 21A ... Positive electrode collector, 21B ... Positive electrode active material layer, 21C, 21D ... End part, 21E, 21F ... End part opposing area | region , 22 ... negative electrode, 22A ... negative electrode current collector, 22B ... negative electrode active material layer, 22C, 22D ... end, 22E, 22F ... end facing region, 23 ... separator, 24 ... coating material, 31 ... exterior member, 32 ... adhesion film.

Claims (2)

A battery comprising an electrode winding body in which a positive electrode and a negative electrode are laminated and wound via an electrolyte inside a film-shaped exterior member,
A covering material covering at least one of an end portion facing the counter electrode in the winding direction of the positive electrode and the negative electrode and a region of the counter electrode facing the end portion;
The coating material includes at least one member selected from the group consisting of polyethylene terephthalate, polyphenylene sulfide, and polyimide, and has a thickness of 5 μm or more. A positive electrode lead is attached to the positive electrode, and a negative electrode lead is attached to the negative electrode.
The battery according to claim 1, wherein at least one of an attachment portion of the positive electrode lead or an attachment portion of the negative electrode lead is covered with the covering material.

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