JP4811983B2 - Winding electrode, manufacturing method thereof, and battery using the same - Google Patents

Description

  The present invention relates to a wound electrode, a method for manufacturing the same, and a battery using the same.

  In recent years, the importance of mobile devices such as mobile phones, PDAs and notebook computers has increased, and the importance of batteries mounted on them has also increased. In particular, due to environmental considerations, the importance of secondary batteries that can be repeatedly charged is increasing. Application of secondary batteries to automobiles, electric bicycles, household power storage systems, commercial power storage systems, and the like has been studied.

  A pair of strip-like electrodes (positive electrode and negative electrode) constituting a battery usually has a structure in which an active material layer containing an active material and a binder is formed on both surfaces of a metal foil. Between the positive electrode and the negative electrode, and on the opposite side of the negative electrode on the positive electrode side, for example, a strip-like polyethylene microporous film is disposed, and a laminate including the positive electrode, the negative electrode, and two separators Is wound, for example, in a cylindrical shape or a flat shape, and is stored in a container together with the electrolyte. The separator insulates the positive electrode and the negative electrode. In a rectangular Li-ion battery normally used for a mobile phone or the like, a wound electrode in which a laminate is wound in a flat shape is used in order to effectively use the volume inside the can.

  Incidentally, it has been proposed to integrate the electrode and the separator before winding so that the electrode and the separator do not shift when the laminate is wound. For example, instead of an independent film such as the polyethylene microporous film, it has been proposed to use a porous insulating layer formed by applying an insulating resin to the active material layer of the negative electrode as a separator ( For example, see Patent Documents 1 to 3).

FIG. 7 shows an example of a conventional wound electrode 11. In FIG. 7, reference numeral 41 denotes a positive electrode, and the positive electrode 41 includes a pair of positive electrode active material layers 41a and 41b and a positive electrode current collector 41c disposed between the positive electrode active material layers 41a and 41b. Reference numeral 31 denotes a negative electrode. The negative electrode 31 includes a pair of negative electrode active material layers 31a and 31b and a negative electrode current collector 31c disposed between the negative electrode active material layers 31a and 31b. 21a and 21b are porous insulating layers, which are joined to the negative electrode active material layers 41a and 41b, respectively. The innermost circumference of the wound electrode 11 is formed from a portion where the negative electrode 31 starts to be rolled, and in the wound electrode 11, the negative electrode 31, the porous insulating layer 21 b, the positive electrode 41, and the porosity from the innermost circumference side toward the outermost circumference side. The insulating layers 21a are arranged in this order. Moreover, the length of the longitudinal direction of the positive electrode 41 and the negative electrode 31 is substantially equal (for example, refer patent document 4).
JP-A-11-288874 JP-A-11-86844 JP 2003-264005 A No. 3557240

  However, if the innermost circumference of the wound electrode including the portion with the largest curvature is composed of the negative electrode 31, the porous insulating layer 21b joined to the negative electrode active layer 31a is likely to crack. If cracks occur in the porous insulating layer 21b, there is a risk of a short circuit between the positive electrode and the negative electrode. Therefore, there is a problem that there is a concern that a short circuit occurs in the portion where the curvature is large. The crack of the porous insulating layer 21b is more likely to occur particularly when the wound electrode is flat.

  The present invention provides a more reliable wound electrode and a battery using the same, in which the risk of cracking of the porous insulating layer is alleviated.

The wound electrode of the present invention includes a pair of band-shaped porous insulating layers, a band-shaped negative electrode including a negative electrode active material layer disposed between the pair of porous insulating layers, and the pair of porous insulating layers. one of the porous insulation layer is laminated on the side positive electrode active band-like positive electrode and containing I to I stack including the material layer of the layers is a wound electrode wound, the negative electrode, the two layers The negative electrode active material layer, a negative electrode current collector disposed between the two negative electrode active material layers, and a negative electrode current collector tab joined to the negative electrode current collector, wherein the negative electrode current collector comprises: A negative electrode active material layer lacking part in which the two negative electrode active material layers are not formed, and the negative electrode current collecting tab is joined to the negative electrode active material layer lacking part, at least said porous insulating layer and the negative electrode are integrated, wherein some or all of the negative electrode active material layer lacking portion, the porous insulating Or covered with an insulating film, the innermost circumference of the wound electrode, characterized in that it consists Maki start portion of the positive electrode.

  The battery of the present invention is characterized in that the wound electrode of the present invention is housed in a container.

The method for manufacturing a wound electrode according to the present invention is a method for manufacturing the wound electrode according to the present invention , wherein a negative electrode active material layer disposed between a pair of negative electrode active material layers and the pair of negative electrode active material layers is provided. A step of applying a paint containing an insulating resin on each negative electrode active material layer of a strip-like negative electrode containing an electric conductor to form a pair of porous insulating layers, a pair of positive electrode active material layers, One porous insulating layer of the pair of porous insulating layers is disposed between the strip-shaped positive electrode including the positive electrode current collector disposed between the pair of positive electrode active material layers and the negative electrode. As described above, a laminate is formed by stacking the positive electrode and the negative electrode, and the laminate is wound so that the positive electrode side of the laminate is on the inside.

In the present invention, the innermost circumference of the wound electrode including the portion with the largest curvature among the wound electrodes is composed of the starting portion of the positive electrode so that the negative electrode integrated with a pair of porous insulating layers is It will be arranged outside the innermost circumference. Therefore, when winding the laminate in the manufacturing process of the wound electrode, the risk of cracking of the porous insulating layer integrated with the negative electrode is alleviated, and as a result, the highly reliable wound electrode and the A battery using can be provided. Further, in the present invention, the negative electrode current collector includes a negative electrode active material layer lacking portion in which the two negative electrode active material layers are not formed at the end of the rolling, and the negative electrode current collecting tab lacks the negative electrode active material layer. Since the negative electrode active material layer is peeled off, adverse effects on the battery are prevented. Further, in the present invention, part or all of the negative electrode active material layer lacking part is covered with the porous insulating layer or the insulating film, so that the negative electrode active material layer of the negative electrode current collector is not formed. About, the insulation between a positive electrode and a negative electrode can be improved.

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

  In the present embodiment, a wound electrode constituting a Li ion battery, a manufacturing method thereof, and a Li ion battery using the wound electrode will be described as an example.

  FIG. 1 shows an example of the wound electrode of the present embodiment, FIG. 2 shows the winding start side of the laminate constituting the wound electrode shown in FIG. 1, and FIG. The end side is shown.

  As shown in FIGS. 1 to 3, the wound electrode 1 of the present embodiment includes a pair of strip-shaped porous insulating layers 2 a and 2 b and a strip-shaped negative electrode 3 disposed between the porous insulating layers 2 a and 2 b. And the laminated body containing the strip | belt-shaped positive electrode 4 has the structure wound by the flat shape. In the example shown in FIGS. 1 to 3, the positive electrode 4 is laminated on one porous insulating layer 2a side of the pair of porous insulating layers 2a and 2b.

  The negative electrode 3 includes two negative electrode active material layers 3a and 3b and a negative electrode current collector 3c disposed between the two negative electrode active material layers 3a and 3b. The positive electrode 4 includes two layers of positive electrode active materials. The material layer 4a, 4b and the positive electrode collector 4c arrange | positioned between the two positive electrode active material layers 4a, 4b are included. The positive electrode active material layers 4a and 4b contain a positive electrode active material capable of releasing lithium ions. The negative electrode active material layers 3a and 3b contain a negative electrode active material capable of inserting and extracting lithium ions released from the positive electrode active material.

  Before and after the laminate is wound, the porous insulating layer 2a is bonded to the negative electrode active material layer 3a, and the porous insulating layer 2b is bonded to the negative electrode active material layer 3b, so that the pair of porous insulating layers 2a and 2b And the negative electrode 3 are integrated. The positive electrode active material layer 4a and the porous insulating layer 2a of the positive electrode 4 and the positive electrode active material layer 4b and the porous insulating layer 2b are not joined before the laminate is wound. After being wound, it may or may not be joined.

  In the wound electrode 1, the innermost circumference including the portion with the largest curvature of the wound electrode 1 is composed of the starting portion 4 d of the positive electrode 4, so that it is integrated with the pair of porous insulating layers 2 a and 2 b. The negative electrode 3 is disposed outside the innermost periphery. Therefore, the risk of cracking of the porous insulating layer 2a integrated with the negative electrode active material layer 3a is reduced when the laminate is wound in the manufacturing process of the wound electrode 1. Therefore, the wound electrode of this embodiment and the battery using the same are highly reliable.

  As shown in FIG. 4, the negative electrode 3 is preferably wider than the positive electrode 4, and both edge portions 3 f in the width direction of the negative electrode 3 are preferably protruding from the positive electrode 4. In the lithium ion battery, lithium dendrite deposited on the peripheral edge of the negative electrode 3 with use of the battery breaks through the porous insulating layers 2a and 2b and contacts the positive electrode 4, causing a short circuit and shortening the life of the battery. There is a problem. If the positive electrode and the negative electrode are arranged so that the width of the negative electrode 3 is larger than that of the positive electrode 4 and both edge portions 3f in the width direction of the negative electrode 3 protrude from the positive electrode 4, the lithium in the both edge portions 3f of the negative electrode 3 Dendrite precipitation can be suppressed, and as a result, a short circuit can be suppressed.

  When the width of the negative electrode 3 is larger than that of the positive electrode 4, the width of the pair of porous insulating layers 2 a and 2 b is preferably larger than that of the positive electrode 4. This is because the negative electrode 3 and the positive electrode 4 can be reliably insulated.

  Of the two positive electrode active material layers 4a and 4b, the positive electrode active material layer 4b wound relatively inside is preferably formed so as to avoid the starting portion 4d ′ of the positive electrode current collector 4c. . Even if a part of the positive electrode active material layer 4b is present on the inner surface of the positive electrode current collector 4c in the starting portion 4d of the positive electrode 4, there is a negative electrode active material layer facing a part of the positive electrode active material layer 4b. Since it does not exist, a part of the positive electrode active material layer does not contribute to charging / discharging. Therefore, from the viewpoint of cost reduction, it is preferable that the positive electrode active material layer 4b is formed avoiding the starting portion 4d ′ of the positive electrode current collector 4c.

  In addition, the positive electrode active material layer 4b wound relatively inside is a case where a pair of positive electrode active material layers 4a and 4b is observed at a predetermined portion of the positive electrode 4 constituting the wound electrode 1. It means the positive electrode active material layer 4b disposed inside. In the wound electrode of this embodiment, the starting portion 4d ′ of the positive electrode current collector 4c is also the starting portion 4d of the positive electrode 4.

Examples of the positive electrode active material included in the positive electrode active material layers 4a and 4b include inorganic oxides such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNi _1/3 Co _1/3 Mn _1/3 O, and LiFePo ₄ . Can be used.

 The positive electrode active material layers 4a and 4b may contain a conductive material, if necessary, in addition to the positive electrode active material. Examples of the conductive material include carbon materials such as acetylene black (AB), ketjen black (KB), graphite, and amorphous carbon. These conductive materials can be used alone or in combination.

  The positive electrode active material layers 4a and 4b were, for example, applied to the positive electrode current collector 4c after applying a slurry obtained by mixing the positive electrode active material, the conductive material, and the binder to the positive electrode current collector 4c. The slurry can be dried and then pressed in the thickness direction. Examples of the binder include fluorine-based materials such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), and rubber-based materials such as styrene butadiene rubber (SBR). These binders can be used alone or in combination.

Examples of the negative electrode active material included in the negative electrode active material layers 3a and 3b include metals that can be alloyed with Li, such as Sn and Si, metal lithium, LiAl alloy, amorphous carbon, artificial graphite, natural graphite, fullerene, Carbon-based materials capable of occluding and releasing lithium such as nanotubes, lithium titanate capable of occluding and releasing lithium such as Li ₄ Ti ₅ O ₁₂ and Li ₂ Ti ₃ O ₇ can be used.

  The negative electrode active material layers 3a and 3b may contain a conductive material as necessary in addition to the negative electrode active material. Examples of the conductive material include carbon materials such as AB, KB, and amorphous carbon. These conductive materials may be used alone or in combination.

  The negative electrode active material layers 3a and 3b were, for example, applied to the negative electrode current collector 3c after a slurry obtained by mixing the negative electrode active material, the conductive material, and the binder was applied to the negative electrode current collector 3c. The slurry can be dried and then pressed in the thickness direction. Examples of the binder include PVDF, PTFE, SBR, carboxymethyl cellulose (CMC) and the like. These binders may be used alone or in combination.

  For example, an Al foil or the like is used for the positive electrode current collector 4c, and for example, a Cu foil or the like is used for the negative electrode current collector 3c.

  The porous insulating layers 2a and 2b are not particularly limited in terms of material, form, and the like as long as they can achieve insulation between the positive electrode 4 and the negative electrode 3 and have pores through which lithium ions can move. The porous insulating layers 2a and 2b are made of, for example, a paint containing organic fine particles and a binder, a paint containing inorganic particles and a binder, or a paint containing organic fine particles, inorganic fine particles and a binder, and negative electrode active material layers 3a and 3b. It can form by apply | coating to. The application can be performed by a doctor blade method or a spray application method. The porous insulating layers 2a and 2b preferably have a so-called shutdown function. The shutdown function refers to a function of closing the pores of the porous insulating layers 2a and 2b and losing the ionic conductivity of the porous insulating layer when the temperature inside the battery rises too much.

  Examples of the organic fine particle material include thermoplastic resins such as polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and polylactic acid. Can be mentioned. Examples of the inorganic fine particle material include inorganic oxides such as alumina and silica. The coating material may contain fine particles made of a composite material containing the thermoplastic resin and the inorganic oxide.

  For example, PVDF, PTFE, SBR, or the like can be used as the binder contained in the paint. In addition, when the organic fine particles themselves have adhesiveness, for example, when the material of the organic fine particles is EVA or the like, the binder is not always necessary.

  The porous insulating layers 2a and 2b can also be formed by the following method. (1) After applying a resin solution in which a resin is dissolved in a solvent (good solvent) to the negative electrode active material layers 3a and 3b, the resin solution is dipped in a poor solvent and dried before being dried. A resin coating film having a structure is coagulated and deposited.

  (2) The resin solution is further mixed with a poor solvent or an inorganic salt, and the obtained paint is applied to the negative electrode active material layers 3a and 3b. Next, the good solvent is dried and removed from the paint applied to the negative electrode active material layers 3a and 3b, and then the poor solvent or the inorganic salt is removed by a method such as drying or extraction to obtain a porous insulating layer.

  Examples of the resin in the resin solution include PVDF, polysulfone, and chlorinated PP, examples of the good solvent include toluene and N-methylpyrrolidone (NMP), and examples of the poor solvent include water and alcohol. As the inorganic salt, for example, LiBr, LiI or the like can be used.

  (3) A microporous film (for example, see Japanese Patent Application Laid-Open No. 2004-2658) made of engineering plastic, hot melt adhesive, tackifier, and inorganic filler is integrated on both sides of the negative electrode by hot pressing or the like. Alternatively, the porous insulating layers 2a and 2b may be used. The microporous film may be formed directly on the negative electrode.

  Also in the wound electrode of this embodiment, as in the conventional wound electrode, the positive electrode has a positive electrode current collecting tab 7 (see FIG. 2) for electrically connecting the positive electrode terminal of the battery and the positive electrode current collector 4c. Includes a negative electrode current collecting tab 8 (see FIG. 3) for electrically connecting the negative electrode terminal of the battery and the negative electrode current collector 3c.

As shown in FIG. 2, the positive electrode current collector 4 c includes a positive electrode active material layer lacking portion 4 c ′ in which the two positive electrode active material layers 4 a and 4 b are not formed on the starting side of the positive electrode active material layer. It is preferable that the positive electrode current collecting tab 7 is joined to the missing portion 4c ′. When the positive electrode active material layer is present on the surface opposite to the surface to which the positive electrode current collector tab 7 of the positive electrode current collector 4c is bonded, the positive electrode active material layer is bonded after the positive electrode current collector 4c and the positive electrode current collector tab 7 are bonded. The battery characteristics may be adversely affected by peeling off. The positive electrode current collector 4c includes a positive electrode active material layer lacking portion 4c ′ in which the two positive electrode active material layers 4a and 4b are not formed, and the positive electrode current collecting tab 7 is joined to the positive electrode active material layer lacking portion 4c ′. In this case, there is no adverse effect on the battery due to peeling off of the positive electrode active material layer. For the same reason, as shown in FIG. 3, with the anode current collector 3c, the anode active material layer 3a of the two layers, 3b are not formed with the negative electrode active material layer lacking portion 3c ', the seeded end side wherein, the negative electrode current collector tab 8 in the negative electrode active material layer lacking portion 3c 'is that are joined.

  Although there is no restriction | limiting in particular about the shape of the positive electrode current collection tab 7 and the positive electrode current collection tab 8, For example, it is strip shape. As the material of the positive electrode current collecting tab 7, for example, Al, Ni or the like is used, and as the material of the negative electrode current collecting tab 8, for example, Cu, Ni or the like is used.

In FIGS. 1 to 3 , the porous insulating layers 2a and 2b are formed only on the negative electrode active material layers 3a and 3b, respectively, but at least one of both surfaces of the negative electrode current collector 3c is negative electrode active. all or part of a portion material layer is not formed, it requires that for instance is covered with a porous insulating layer. If at least one of both surfaces of the negative electrode current collector 3c is formed with a porous insulating layer so as to cover all or part of the portion where the negative electrode active material layer is not formed, The insulating property between the positive electrode 4 and the negative electrode 3 can be enhanced at a portion of the body 3c where the negative electrode active material layer is not formed. Insulation between the positive electrode 4 and the negative electrode 3 in a portion of the negative electrode current collector 3c where the negative electrode active material layer is not formed is an insulation containing a resin that is stable in the electrolyte, for example, a resin such as polyethylene, polypropylene, or polyimide. You may carry out using a property film.

  In the wound electrode 1 of the present embodiment, the positive electrode 4 is preferably longer in the longitudinal direction than the negative electrode 3, and the outermost periphery of the wound electrode is preferably composed of the end 4 f (see FIG. 3) of the positive electrode 4. For example, when the battery container using the wound electrode 1 of the present embodiment is an Al can, the Al can and the positive electrode of the wound electrode 1 are electrically connected in the battery. When the outermost periphery of the wound electrode 1 is composed of the end portion 4f of the positive electrode 4, it is possible to reliably prevent a short circuit between the negative electrode of the wound electrode 1 and the Al can (which has the same potential as the positive electrode 4 of the wound electrode 1). The reliability of the battery can be increased.

  Next, an example of the manufacturing method of the winding electrode of this embodiment is demonstrated.

  First, as shown in FIG. 5A, a strip-like positive electrode 4 including a pair of positive electrode active material layers 4a and 4b and a positive electrode current collector 4c disposed between the pair of positive electrode active material layers 4a and 4b. Prepare. On the other hand, a strip-like negative electrode 3 including a pair of negative electrode active material layers 3a and 3b and a negative electrode current collector 3c disposed between the pair of negative electrode active material layers 3a and 3b is prepared. In FIG. 5A, 7 is a positive electrode current collecting tab, and 8 is a negative electrode current collecting tab. The positive electrode current collector tab 7 is bonded to the positive electrode current collector 4c, and the negative electrode current collector tab 8 is bonded to the negative electrode current collector 3c, respectively, using a conductive adhesive (for example, silver paste).

Next, as illustrated in FIG. 5B, a pair of porous insulating layers 2a and 2b is formed by applying a coating containing an insulating resin on the negative electrode active material layers 3a and 3b, respectively. In addition, at least one of both surfaces of the negative electrode current collector 3c is covered with a porous insulating layer or an insulating film at all or part of the portion where the negative electrode active material layer is not formed. Thus, if the porous insulating layers 2a and 2b are formed by the method of applying a paint, for example, a thinner porous insulating layer can be formed than when an independent film is used as the porous insulating layer. Therefore, the volume occupied by the pair of porous insulating layers 2a and 2b in the wound electrode can be reduced to increase the filling amount of the positive electrode active material and the negative electrode active material, and the capacity of the battery can be increased. Become.

  As the insulating resin, for example, the following are used.

  When the paint containing an insulating resin is the above-described paint containing organic fine particles and optionally a binder, or a paint containing inorganic particles and a binder, the insulating resin is organic fine particles or a binder, for example, , Polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), thermoplastic resins such as polylactic acid, PVDF, PTFE, SBR, etc. .

  When the paint containing the insulating resin is the above-described resin solution in which the resin is dissolved in a solvent (good solvent) (including those containing a poor solvent or an inorganic salt added), the insulating resin is a resin solution. For example, PVDF, polysulfone, chlorinated PP, and the like.

  Next, as shown in FIG. 5C, the positive electrode 4 and the negative electrode are arranged such that one porous insulating layer 2 a of the pair of porous insulating layers 2 a and 2 b is disposed between the positive electrode 4 and the negative electrode 3. 3 are stacked to form a laminate. At this time, the positive electrode 4 and the negative electrode 3 are overlapped so that the innermost circumference of the wound electrode obtained by winding the laminate is composed of the starting portion 4 d of the positive electrode 4. In the example shown in FIG. 5C, the positive electrode 4 and the negative electrode 3 are overlapped so that the starting start side end 4 g of the positive electrode 4 protrudes from the starting start side end 3 g of the negative electrode 3. The positive electrode 4 and the negative electrode 3 may be overlapped so that the side end surface 4h and the starting side end surface 3h of the negative electrode 3 are aligned. In the laminated body, one porous insulating layer 2a of the pair of porous insulating layers 2a and 2b and the positive electrode 4 are in contact with each other in a non-bonded state.

  Note that “the starting start side end surface 4h of the positive electrode 4 and the starting start side end surface 3h of the negative electrode 3 are aligned” means that the starting start side end surface 4h of the positive electrode 4 and the starting start side end surface 3h of the negative electrode 3 are substantially aligned. For example, it includes a case where it is slightly shifted due to a manufacturing error.

  Next, the laminate is wound into, for example, a flat shape so that the positive electrode 4 is inside the negative electrode 3 to form a wound electrode. The laminated body obtained by stacking the positive electrode 4 and the negative electrode 3 so that the rolling start side end 4g of the positive electrode 4 protrudes from the rolling start side end 3g of the negative electrode 3 is wound so that the positive electrode 3 is inside. Therefore, the innermost circumference of the wound electrode is composed of a starting portion 4d of the positive electrode 4 (see FIG. 5C).

  Thus, according to the method for manufacturing a wound electrode of the present embodiment, the negative electrode 3 in which the pair of porous insulating layers 2a and 2b are integrated is disposed outside the innermost circumference of the wound electrode. It will be. Therefore, even if a thin porous insulating layer is formed by applying a paint, the risk of cracking of the porous insulating layer integrated with the negative electrode 3 can be reduced when the laminate is wound. As a result, the method for manufacturing a wound electrode according to the present embodiment can provide a highly reliable wound electrode and a battery using the wound electrode.

  In the manufacturing method of the wound electrode of the present embodiment, the wound body obtained by winding the laminated body is heated while being pressed to join the pair of porous insulating layers 2a and 2b and the positive electrode 4. It is preferable to further include an integration step. When the porous insulating layers 2a and 2b and the positive electrode 4 are joined, handling of the wound electrode (rolled body) becomes easy, and the wound electrode can be easily housed in the container.

  In the integration step, the pressure is suitably, for example, 50 Pa to 500 Pa. The heating temperature is suitably, for example, not less than the softening point of the insulating resin contained in the porous insulating layers 2a and 2b. Although there is no restriction | limiting in particular about the upper limit of heating temperature, Usually, it is preferable in it being 200 degrees C or less. If the heating temperature is too high, the binder contained in the positive electrode active material layers 4a and 4b and the negative electrode active material layers 3a and 3b deteriorates, and the positive electrode active material layers 4a and 4b are changed from the positive electrode current collector 4c to the negative electrode current collector 3c. This is because there is a problem that the negative electrode active material layers 3a and 3b are peeled off from each other, which may deteriorate the electrode characteristics.

  In the manufacturing method of the wound electrode of the present embodiment, the length in the longitudinal direction is larger than that of the negative electrode 3 so that the outermost periphery of the wound body obtained by winding the laminated body is composed of the end portion 4f of the positive electrode 4. It is preferable to prepare a longer positive electrode 4. In this way, it is possible to produce a wound electrode in which the outermost periphery of the wound electrode is composed of the end portion 4 f of the positive electrode 4.

  Next, an example of the battery of this embodiment will be described.

  FIG. 6 shows an example (cross-sectional view) of the battery of the present embodiment in which the wound electrode shown in FIGS. 1 to 3 is housed in a container together with an electrolytic solution. In FIG. 6, the wound electrode 1 is simply illustrated for convenience of illustration, and hatching is also omitted. In FIG. 6, 4 is a positive electrode and 3 is a negative electrode.

  As shown in FIG. 6, in the battery of this embodiment, the container 9 including the lid 9a is formed of a metal such as aluminum (Al). An insulator 5 made of a synthetic resin such as a PTFE sheet is disposed at the bottom of the container 9. A metal terminal 11 made of stainless steel or the like is attached to the lid 9a via an insulating packing 10 made of synthetic resin such as PP, and a metal lead plate such as stainless steel is attached to the terminal 11 via an insulator 12. 13 is attached.

In the example shown in FIG. 6, the positive electrode current collecting tab 7 is directly welded to the lid body 9a, so that the container functions as a positive electrode terminal. Further, anode current indenter Bed 8 is welded to the lead plate 13, and the anode current indenter blanking 8 and the terminal 11 via a lead plate 13 is conductive. The terminal 11 functions as a negative terminal. Depending on the material of the container, the sign of the terminal may be reversed. The container may be made of, for example, stainless steel (SUS).

  The battery of this embodiment is not limited to the form shown in FIG. 6, and the container may include a resin film processed into a bag shape. The resin film preferably contains a material capable of sealing the opening of the container by thermal welding or the like after the wound electrode 1 is contained in the container, for example, a polyolefin such as polyethylene or polypropylene. The resin film may have a laminate structure including a metal foil.

Although there is no restriction | limiting in particular as electrolyte solution, When a battery is a Li ion battery, what melt | dissolved Li salt in the organic solvent is used, for example. The Li salt is not particularly limited as long as it can be dissociated in an organic solvent to generate Li ⁺ ions and does not cause a side reaction such as decomposition in the voltage range of a battery having an electrolytic solution as a component.

Examples of the Li salt include inorganic compounds such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ). (SO ₂ C ₄ F ₉ ), LiC (SO ₂ CF ₂ ) ₃ , LiC (SO ₂ C ₂ F ₅ ) ₃ , LiPF _6-n (C ₂ F ₅ ) _n (n is an integer from 1 to 6) Organic compounds such as LiSO ₃ CF ₃ , LiSO ₃ C ₂ F ₅ , and LiSO ₃ C ₄ F ₈ can be used.

  The organic solvent is not limited as long as it can dissolve the Li salt and does not cause side reactions such as decomposition in the voltage range of the battery. Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, cyclic esters such as γ-butyrolactone, dimethoxyethane, and diglyme. And chain ethers such as triglyme and tetraglyme, cyclic ethers such as dioxane, tetrahydrofuran and 2-methyltetrahydrofuran, and nitriles such as acetonitrile, propionitrile, methoxypropionitrile and ethoxypropionitrile. These organic solvents can be used alone or in combination.

  Especially, as an organic solvent, the mixed solvent of ethylene carbonate and a chain carbonate is preferable. By using the above mixed solvent, high electrical conductivity can be obtained and good battery characteristics can be realized.

  For the purpose of improving characteristics such as safety, cycleability, and high-temperature storage properties, the electrolyte solution is appropriately vinylene carbonates, 1,3-propane sultone, diphenyl disulfide, cyclohexane, biphenyl, fluorobenzene, t-butyl. Additives such as benzene may be included.

  In addition, the electrolytic solution is replaced with an organic solvent, such as ethyl-methylimidazolium trifluoromethylsulfonium imide, heptyl-trimethylammonium trifluoromethylsulfonium imide, pyridinium trifluoromethylsulfonium imide, guanidinium trifluoromethylsulfonium imide, etc. Of room temperature molten salt.

  Moreover, electrolyte solution contains the following host polymer and may be gelatinized with the host polymer. The host polymer includes polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide copolymer, crosslinked polymer containing an ethylene oxide chain in the main chain or side chain, photo And a (meth) acrylate copolymer which can be cross-linked by heat and has an oxetane compound or an alicyclic epoxy compound in the side chain.

  In the present invention, the risk of cracking of the porous insulating layer can be alleviated and a short circuit between the positive electrode and the negative electrode can be suppressed, so that a more reliable wound electrode and a battery using the same can be provided. Therefore, the wound electrode of the present invention, the manufacturing method thereof, and the battery using the same are useful.

Sectional drawing which showed an example of the wound electrode of this invention Sectional drawing which showed the winding start side of the laminated body which comprises the winding electrode shown in FIG. Sectional drawing which showed the winding end side of the laminated body which comprises the winding electrode shown in FIG. The top view of the laminated body which comprises the winding electrode shown in FIG. 1 process sectional drawing explaining an example of the manufacturing method of the winding electrode of this invention 1 process sectional drawing explaining an example of the manufacturing method of the winding electrode of this invention 1 process sectional drawing explaining an example of the manufacturing method of the winding electrode of this invention Sectional drawing which showed an example of the battery of this invention Sectional view showing an example of a conventional wound electrode

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Winding electrode 2a, 2b Porous insulating layer 3 Negative electrode 3a, 3b Negative electrode active material layer 3c Negative electrode collector 3f Both edges 3g Rolling start side end 3h Rolling start side end surface 4 Positive electrode 4a, 4b Positive electrode active material layer 4c Positive electrode current collector 4d Starting part 4f Ending part 4g Ending side end 4h Ending side end face 7 Positive current collecting tab 8 Negative current collecting tab 9 Container

Claims (13)

A pair of band-shaped porous insulating layers, a band-shaped negative electrode including a negative electrode active material layer disposed between the pair of porous insulating layers, and one of the pair of porous insulating layers A laminate including a belt-like positive electrode laminated on the insulating layer side and including a positive electrode active material layer is a wound electrode,
The negative electrode includes two layers of the negative electrode active material layer, a negative electrode current collector disposed between the two negative electrode active material layers, and a negative electrode current collector tab joined to the negative electrode current collector. ,
The negative electrode current collector includes a negative electrode active material layer-deficient portion on which the two negative electrode active material layers are not formed,
The negative electrode current collecting tab is bonded to the negative electrode active material layer lacking part,
The pair of porous insulating layers and at least the negative electrode are integrated;
Part or all of the negative electrode active material layer lacking part is covered with the porous insulating layer or insulating film,
The wound electrode is characterized in that an innermost circumference of the wound electrode is formed from a portion where the positive electrode starts rolling.   The wound electrode according to claim 1, wherein the laminate is wound in a flat shape. The positive electrode active material layer includes a positive electrode active material capable of releasing lithium ions,
The negative electrode active material layer includes a negative electrode active material capable of occluding and releasing lithium ions released from the positive electrode active material,
The wound electrode according to claim 1, wherein the negative electrode is wider than the positive electrode, and both edges in the width direction of the negative electrode protrude from the positive electrode.   2. The wound electrode according to claim 1, wherein the positive electrode has a longer length in the longitudinal direction than the negative electrode, and an outermost periphery of the wound electrode is formed of a portion where the positive electrode ends. The positive electrode includes two positive electrode active material layers and a positive electrode current collector disposed between the two positive electrode active material layers,
5. The positive electrode active material layer wound relatively inward among the two positive electrode active material layers is formed so as to avoid a starting portion of the positive electrode current collector. The wound electrode according to the item. The positive electrode current collector includes a positive electrode active material layer-deficient portion on which the two positive electrode active material layers are not formed on the starting side thereof,
The wound electrode according to claim 5, wherein the positive electrode includes a positive electrode current collecting tab joined to the positive electrode active material layer lacking part.   The wound electrode according to any one of claims 1 to 6, wherein the porous insulating layer contains inorganic fine particles and a binder.   A battery, wherein the wound electrode according to any one of claims 1 to 7 is contained in a container.   The battery according to claim 8, wherein the container is made of Al or stainless steel.   The battery according to claim 8, wherein the container includes a resin film processed into a bag shape. A method for producing a wound electrode according to any one of claims 1 to 7,
A paint containing an insulating resin is applied on each negative electrode active material layer of a strip-shaped negative electrode including a pair of negative electrode active material layers and a negative electrode current collector disposed between the pair of negative electrode active material layers. Forming a pair of porous insulating layers ;
Between the negative electrode and the strip-shaped positive electrode including a pair of positive electrode active material layers and a positive electrode current collector disposed between the pair of positive electrode active material layers, the pair of porous insulating layers one of the porous insulating layer among the
Including stacking the positive electrode and the negative electrode to form a laminate,
A method for producing a wound electrode, comprising winding the laminate so that the positive electrode side of the laminate is on the inside.   The method for manufacturing a wound electrode according to claim 11, wherein in the winding step, the laminate is wound in a flat shape. In the laminate, the porous insulating layer and the positive electrode are in contact with each other in a non-bonded state,
After the wound process, and heated under pressure the wound body, the multi-porous manufacturing method of wound electrode according to claim 12, further comprising an integrating step of the insulating layer to bonding the positive electrode .

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