JPWO2012093588A1 - Non-aqueous secondary battery - Google Patents

Abstract

The lithium ion secondary battery (non-aqueous secondary battery) includes a positive electrode current collector 11 having a multilayer structure in which a resin layer 13 is sandwiched between conductive layers 14 and a positive electrode active material layer formed on the positive electrode current collector 11. 12, a metal member 80 that electrically connects the plurality of positive electrodes 10 to each other, and a tab electrode 41 that is electrically connected to the positive electrode 10. Each of the plurality of positive electrodes 10 has a current collector exposed portion 11 a in which the conductive layer 14 is exposed without forming the positive electrode active material layer 12. The metal member 80 is bent in a zigzag manner and is disposed between the current collector exposed portions 11 a of the plurality of positive electrodes 10.

Description

  The present invention relates to a non-aqueous secondary battery.

  Non-aqueous secondary batteries represented by lithium ion secondary batteries have high capacity and high energy density, and are excellent in storage performance and charge / discharge repetition characteristics. It's being used. In recent years, lithium ion secondary batteries have come to be used for electric power storage applications and in-vehicle applications such as electric vehicles due to increasing awareness of environmental issues and energy savings.

  On the other hand, the non-aqueous secondary battery has a high risk of abnormal overheating or ignition when exposed to an overcharged state or a high temperature environment because of its high energy density. Therefore, various countermeasures for safety are taken in the non-aqueous secondary battery.

  Conventionally, in order to prevent ignition due to abnormal heat generation, a lithium ion secondary battery using a current collector having a multilayer structure has been proposed (for example, see Patent Document 1).

  Patent Document 1 proposes a lithium ion secondary battery using a current collector in which metal layers are formed on both surfaces of a resin film having a low melting point of 130 ° C. to 170 ° C. In this lithium ion secondary battery, when abnormal heat generation occurs in an overcharged state or a high temperature state, the low melting point resin film melts. And the electrode is damaged by melting of the resin film. Thereby, since an electric current is cut, the temperature rise inside a battery is suppressed and ignition is prevented.

JP-A-11-102711

  As described above, the current collector proposed in Patent Document 1 is very effective as a safety measure for non-aqueous secondary batteries.

  However, since the current collector has a configuration in which metal layers are formed on both surfaces of an insulating resin film, for example, in the case of a stacked non-aqueous secondary battery in which a plurality of electrodes are stacked, wiring When connecting the lead tab electrode to the current collector, there is an inconvenience that the electrodes cannot conduct each other. For this reason, since it becomes difficult to electrically connect the tab electrode to all the electrodes, there is a problem that the battery performance is remarkably deteriorated.

  The present invention has been made to solve the above-described problems, and one object of the present invention is a non-aqueous secondary that can improve the safety and suppress the deterioration of the battery performance. It is to provide a battery.

  In order to achieve the above object, a non-aqueous secondary battery according to one aspect of the present invention includes a current collector having a multilayer structure in which an insulating layer is sandwiched between conductive layers, and an active material layer formed on the current collector. A conductive member that electrically connects the plurality of electrodes to each other, and a tab electrode that is electrically connected to the electrodes. Each of the plurality of electrodes has a current collector exposed portion in which the conductive layer is exposed without forming the active material layer, and the conductive member is folded in a zigzag manner to collect the current in the plurality of electrodes. It is arranged between the exposed electrical parts.

  In the non-aqueous secondary battery according to the one aspect, as described above, the conductive member folded in a zigzag manner is disposed between the current collector exposed portions, and the conductive in the plurality of electrodes is interposed via the conductive member. The layers can be electrically connected to each other. For this reason, even when a current collector having a multilayer structure is used, conduction between the plurality of stacked electrodes can be achieved. Thereby, the tab electrode can be electrically connected to the plurality of stacked electrodes. For example, the tab electrode can be electrically connected to all the stacked electrodes of the same polarity. Therefore, since the deterioration of battery performance can be suppressed, the performance of the nonaqueous secondary battery can be fully utilized.

  Also, in one aspect, by using a current collector having a multilayer structure as described above, for example, when an abnormal heat generation occurs in an overcharged state or a high temperature state, the insulating layer of the current collector is melted. Since the electrode is broken, the current can be cut. Thereby, since the temperature rise inside a battery can be suppressed, it can prevent that abnormal states, such as ignition, arise.

  In one aspect, by providing the conductive member, for example, when the tab electrode is connected to the electrode by welding or the like, the contact resistance between the tab electrode and the electrode and the contact resistance between the electrodes are reduced. Can do. Thereby, the tab electrode can be firmly connected to the electrode. Note that, by firmly connecting the tab electrode to the electrode, a decrease in battery capacity due to an increase in contact resistance can be suppressed. In addition, durability and vibration resistance can be improved.

  In the nonaqueous secondary battery according to the above aspect, the conductive member is preferably made of a metal foil. If comprised in this way, while being able to arrange | position a electrically-conductive member between current collector exposed parts easily, it can make it easy to take conduction | electrical_connection between electrodes.

  In the non-aqueous secondary battery according to the above aspect, the conductive member preferably has a zigzag shape that is bent outside the electrode. If comprised in this way, the conductive layer in a some electrode can be electrically connected mutually easily via this electrically-conductive member.

  In the non-aqueous secondary battery according to the above aspect, it is preferable that the current collector exposed portion is provided at an end portion of the electrode, and the conductive member is arranged along the current collector exposed portion.

  In the non-aqueous secondary battery according to the above aspect, the conductive member is preferably fixed to the current collector, and the tab electrode is connected to the conductive member. If comprised in this way, it can make it easy to take conduction with a tab electrode and an electrode.

  In the non-aqueous secondary battery according to the above aspect, it is preferable that the conductive layer and the conductive member of the current collector are made of the same metal material.

  In the non-aqueous secondary battery according to the above aspect, the electrode preferably includes a positive electrode and a negative electrode, and at least one of the positive electrode and the negative electrode is formed using a current collector having a multilayer structure. If comprised in this way, the safety | security of a non-aqueous secondary battery can be improved effectively.

  In the configuration having the positive electrode and the negative electrode, when the positive electrode is formed using the current collector having a multilayer structure, the conductive layer of the current collector in the positive electrode is preferably composed of aluminum. Moreover, when the negative electrode is formed using the said collector which has a multilayer structure, it is preferable that the conductive layer of the collector in a negative electrode is comprised from copper.

  In the nonaqueous secondary battery according to the above aspect, the insulating layer of the current collector is preferably made of a resin material having a melting temperature of 200 ° C. or lower. With this configuration, for example, when abnormal heat generation occurs in an overcharged state, a high temperature state, or the like, the electrode can be easily damaged, so that an abnormal state such as ignition can be effectively prevented. can do. For this reason, the safety | security of a non-aqueous secondary battery can be improved effectively.

  In the non-aqueous secondary battery according to the above aspect, the insulating layer of the current collector preferably has a heat shrinkage rate at 120 ° C. of 1.5% or more in either the vertical direction or the horizontal direction. It consists of a thermoplastic resin. If comprised in this way, when abnormal heat_generation | fever generate | occur | produces in an overcharge state, a high temperature state, etc., for example, an electrode can be easily damaged. For this reason, it is possible to more effectively prevent an abnormal state such as ignition. Thereby, the safety | security of a non-aqueous secondary battery can be improved more effectively.

  In the non-aqueous secondary battery according to the above aspect, the insulating layer of the current collector is preferably made of a film-like or fibrous resin.

  In the non-aqueous secondary battery according to the one aspect, preferably, the insulating layer of the current collector is a resin containing any of polyolefin resins, or a resin containing any of polystyrene, polyvinyl chloride, and polyamide, or It consists of these composite materials. If comprised in this way, the safety | security of a non-aqueous secondary battery can be improved more easily.

  In the non-aqueous secondary battery according to the above aspect, preferably, the electrode includes a positive electrode and a negative electrode, and further includes a separator disposed between the positive electrode and the negative electrode, and the separator is higher than the insulating layer. It has a heat distortion temperature. If comprised in this way, before the shutdown function of a separator operates, the insulating layer which comprises the electrical power collector of an electrode can be blown out. As a result, the current interruption effect by the insulating layer and the separator makes it possible to interrupt the current in two stages, so that the safety of the non-aqueous secondary battery can be further improved.

  In this case, preferably, the separator is made of a material having a heat shrinkage rate of 1.0% or less at a temperature equal to or lower than the heat deformation temperature of the insulating layer. If comprised in this way, when abnormal heat_generation | fever generate | occur | produces in an overcharge state, a high temperature state, etc., an electrode can be made easy to be damaged easily. That is, the insulating layer constituting the current collector of the electrode can be easily blown before the shutdown function of the separator is activated.

  Further, in this case, preferably, the thermal contraction rate of the separator at 180 ° C. is 1.0% or less. If comprised in this way, when abnormal heat_generation | fever generate | occur | produces in an overcharge state, a high temperature state, etc., generation | occurrence | production of the internal short circuit resulting from the thermal contraction of a separator can be suppressed easily. Thereby, since it can suppress that a rapid temperature rise arises, the safety | security of a non-aqueous secondary battery can further be improved.

  In the configuration including the separator, the separator preferably includes any one of an aramid resin, a polyester resin, and a cellulose resin.

  As described above, according to the present invention, it is possible to easily obtain a non-aqueous secondary battery capable of suppressing a decrease in battery performance while improving safety.

It is the perspective view which showed typically a part of electrode group of the lithium ion secondary battery by 1st Embodiment of this invention. It is the top view which showed typically a part of electrode group (positive electrode) used for the lithium ion secondary battery by 1st Embodiment of this invention. It is a disassembled perspective view (the figure which abbreviate | omitted the metal member) of the lithium ion secondary battery by 1st Embodiment of this invention. It is a disassembled perspective view (the figure which abbreviate | omitted the metal member) of the electrode group of the lithium ion secondary battery by 1st Embodiment of this invention. It is sectional drawing (figure corresponding to the cross section along the B1-B1 line | wire of FIG. 6) which showed typically the metal member of the lithium ion secondary battery by 1st Embodiment of this invention. It is the perspective view which showed typically the metal member of the lithium ion secondary battery by 1st Embodiment of this invention. It is the perspective view (figure corresponding to the section along the A1-A1 line of Drawing 2) showing typically the electrode group (positive electrode part) of the lithium ion secondary battery by a 1st embodiment of the present invention. It is sectional drawing which showed typically the electrode group of the lithium ion secondary battery by 1st Embodiment of this invention. 1 is an overall perspective view of a lithium ion secondary battery according to a first embodiment of the present invention. It is sectional drawing which expanded and showed a part of FIG. FIG. 14 is a cross-sectional view of the positive electrode of the lithium ion secondary battery according to the first embodiment of the present invention (a view corresponding to a cross section taken along line C1-C1 in FIG. 13). It is a top view of the positive electrode of the lithium ion secondary battery by 1st Embodiment of this invention. 1 is a perspective view of a positive electrode of a lithium ion secondary battery according to a first embodiment of the present invention. It is sectional drawing (the figure corresponding to the cross section along the C2-C2 line | wire of FIG. 16) of the negative electrode of the lithium ion secondary battery by 1st Embodiment of this invention. It is a top view of the negative electrode of the lithium ion secondary battery by 1st Embodiment of this invention. 1 is a perspective view of a negative electrode of a lithium ion secondary battery according to a first embodiment of the present invention. 1 is a perspective view of a separator of a lithium ion secondary battery according to a first embodiment of the present invention. It is the perspective view which showed typically a part (other example) of the electrode group of the lithium ion secondary battery by 1st Embodiment of this invention. It is sectional drawing (figure corresponding to FIG. 7) which showed typically a part of lithium ion secondary battery by the modification of 1st Embodiment. It is the top view which showed typically a part of electrode group (positive electrode) used for the lithium ion secondary battery by 2nd Embodiment of this invention. It is the figure which showed typically the cross section along the A2-A2 line | wire of FIG. It is sectional drawing (figure corresponding to the section which met the B2-B2 line of Drawing 23) showing typically the metallic member of the lithium ion secondary battery by a 2nd embodiment of the present invention. It is the perspective view which showed typically the metal foil of the lithium ion secondary battery by 2nd Embodiment of this invention. It is the top view which showed typically a part of electrode group (positive electrode) used for the lithium ion secondary battery by the modification of 2nd Embodiment. It is the figure which showed typically the cross section along the A3-A3 line | wire of FIG. It is the top view which showed typically a part of electrode group (positive electrode) used for the lithium ion secondary battery by 3rd Embodiment of this invention. It is sectional drawing which showed typically the metal member of the lithium ion secondary battery by 3rd Embodiment of this invention. It is the figure which showed typically the cross section along the A4-A4 line | wire of FIG. It is the top view which showed typically a part of electrode group (positive electrode) used for the lithium ion secondary battery by the modification of 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. In the following embodiments, a case where the present invention is applied to a stacked lithium ion secondary battery which is an example of a non-aqueous secondary battery will be described.

(First embodiment)
FIG. 1 is a perspective view schematically showing a part of an electrode group of a lithium ion secondary battery according to a first embodiment of the present invention. FIG. 2 is a plan view schematically showing a part of an electrode group (positive electrode) used in the lithium ion secondary battery according to the first embodiment of the present invention. 3 to 17 are views for explaining the lithium ion secondary battery according to the first embodiment of the present invention. First, with reference to FIGS. 1-17, the lithium ion secondary battery by 1st Embodiment of this invention is demonstrated.

  As shown in FIGS. 3 and 9, the lithium ion secondary battery according to the first embodiment is a large-sized secondary battery having a square flat shape, and an electrode group 50 including a plurality of electrodes 5 (see FIGS. 3 and 4). ) And a metal outer container 100 that encloses the electrode group 50 together with a non-aqueous electrolyte.

  As shown in FIGS. 3, 4, and 8, the electrode 5 includes a positive electrode 10 and a negative electrode 20. A short circuit between the positive electrode 10 and the negative electrode 20 is provided between the positive electrode 10 and the negative electrode 20. A separator 30 for suppressing the above is disposed. Specifically, the positive electrode 10 and the negative electrode 20 are arranged so as to face each other with the separator 30 interposed therebetween, and the positive electrode 10, the separator 30, and the negative electrode 20 are sequentially laminated, thereby forming a laminated structure (laminated body). It is configured. Note that the positive electrodes 10 and the negative electrodes 20 are alternately stacked one by one. The electrode group 50 is configured such that one positive electrode 10 is positioned between two adjacent negative electrodes 20.

  The electrode group 50 includes, for example, 13 positive electrodes 10, 14 negative electrodes 20, and 28 separators 30. The positive electrodes 10 and the negative electrodes 20 are alternately stacked with the separators 30 interposed therebetween. Further, a separator 30 is disposed on the outermost side of the electrode group 50 (outside of the outermost negative electrode 20), and insulation from the outer container 100 is achieved.

  In addition, the lithium ion secondary battery according to the first embodiment further includes a metal member 80 bent in a zigzag manner as shown in FIGS. 1, 5, and 6. As will be described later, the metal member 80 is attached to the electrode (positive electrode 10) while being disposed between the electrodes (between the positive electrodes 10). The metal member 80 has a function of electrically connecting the plurality of positive electrodes 10 to each other. The metal member 80 is an example of the “conductive member” in the present invention.

  As shown in FIGS. 8 and 11, the positive electrode 10 constituting the electrode group 50 has a configuration in which the positive electrode active material layer 12 is supported on both surfaces of the positive electrode current collector 11.

  The positive electrode current collector 11 has a function of collecting the positive electrode active material layer 12.

  Here, in the first embodiment, the positive electrode current collector 11 has a multilayer structure (three-layer structure) in which the conductive layers 14 are formed on both surfaces of the insulating resin layer 13. The positive electrode current collector 11 is an example of the “current collector” in the present invention, and the resin layer 13 is an example of the “insulating layer” in the present invention.

  The conductive layer 14 constituting the positive electrode current collector 11 is made of, for example, aluminum or an aluminum alloy, and has a thickness of about 6 μm to about 15 μm. Since aluminum has high oxidation resistance, it can be suitably used as the conductive layer 14 of the positive electrode current collector 11. In addition, the said conductive layer 14 may be other than aluminum or aluminum alloy, for example, may be comprised from metal materials, such as titanium, stainless steel, nickel, or these alloys.

  The method for forming the conductive layer 14 is not particularly limited, and examples thereof include a method by vapor deposition, sputtering, electrolytic plating, electroless plating, bonding of metal foil, and the like, and a method including a combination of these methods.

  The resin layer 13 of the positive electrode current collector 11 is made of a plastic material made of a thermoplastic resin. This resin layer 13 consists of a film-like resin member (resin film), for example. As a plastic material made of a thermoplastic resin, for example, polyolefin resins such as polyethylene (PE) and polypropylene (PP) having a heat distortion temperature of 150 ° C. or less, polystyrene (PS), polyvinyl chloride, polyamide, etc. are preferably used. It is done. Among these, polyolefin resins such as polyethylene (PE) and polypropylene (PP) having a heat shrinkage rate at 120 ° C. of 1.5% or more in either the vertical or horizontal direction, polyvinyl chloride, and the like are preferable. Moreover, these composite films and the resin film which gave these surface treatment processes can also be used suitably. Furthermore, a resin film made of the same material as that of the separator 30 can be used. Further, any resin having different heat deformation temperature, heat shrinkage rate, etc. can be used for both the resin layer 13 and the separator 30 due to differences in manufacturing process and processing.

  Further, the thickness of the resin layer 13 is not particularly limited, but is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 40 μm or less in order to balance the improvement of energy density and the strength maintenance as a secondary battery. preferable. The resin layer 13 (resin film) may be a resin film manufactured by any method such as uniaxial stretching, biaxial stretching, or non-stretching. Further, the resin layer 13 of the positive electrode current collector 11 may be, for example, in the form of a fiber other than a film.

  The heat distortion temperature and the heat shrinkage mean values obtained by the following method. The heat deformation temperature means a temperature at which the resin layer (resin film) starts to shrink (the same applies to the separator described later).

  The heat distortion temperature is kept at a constant temperature for a certain time in a thermostatic chamber, the heat shrinkage rate is measured, the temperature is increased if not contracted, the temperature is decreased if contracted, and this is repeated. To measure. Specifically, a resin film is hold | maintained for 15 minutes, for example at 100 degreeC, and the thermal contraction rate of a resin film is measured. When the heat shrinkage rate at this time is 20% or less, the temperature is raised to 105 ° C. using a new sample, and the heat shrinkage rate is measured after maintaining at this temperature for 15 minutes. This process is repeated until the temperature reaches 150 ° C., and the temperature at which the heat shrinkage rate becomes 10% or more is defined as the heat distortion temperature.

  Moreover, the measurement of a thermal contraction rate attaches two points on the resin film at intervals of 50 mm or more, for example, and measures the distance between both points using a caliper. Then, after heat-processing for 15 minutes at 120 degreeC (180 degreeC also about the separator mentioned later), the distance between the same points is measured again, and a thermal contraction rate is calculated | required based on the measured value before and behind heat processing. Based on this method, the distance between three or more points in each of the longitudinal direction and lateral direction of the resin layer (resin film) is measured, and the average value of the heat shrinkage calculated from each measurement result is determined as the final resin. Adopted as the thermal shrinkage of the film. At this time, for each of the longitudinal direction and the lateral direction of the resin film, at least two points within 10% from the end of the resin film and one point around 50% from the end of the resin film are measured for the distance between the points. Select as a point. The large value of either length or width is taken as the heat shrinkage rate.

The positive electrode active material layer 12 includes a positive electrode active material that can occlude and release lithium ions. Examples of the positive electrode active material include an oxide containing lithium. Specific examples include LiCoO ₂ , LiFeO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , and compounds in which transition metals in these oxides are partially substituted with other metal elements. Among these, in a normal use, it is preferable to use a material that can utilize 80% or more of the amount of lithium held by the positive electrode for the battery reaction. As a result, the safety of the secondary battery against accidents such as overcharging can be enhanced. As such a positive electrode active material, for example, a compound having a spinel structure such as LiMn ₂ O ₄ and Li _X MPO ₄ (M is at least one selected from Co, Ni, Mn, and Fe). And a compound having an olivine structure represented by (element). Among these, a positive electrode active material containing at least one of Mn and Fe is preferable from the viewpoint of cost. Furthermore, it is preferable to use LiFePO ₄ from the viewpoint of safety and charging voltage. In LiFePO ₄ , since all oxygen (O) is bonded to phosphorus (P) by a strong covalent bond, release of oxygen due to a temperature rise hardly occurs. Therefore, it is excellent in safety.

  In addition, the thickness of the positive electrode active material layer 12 is preferably about 20 μm to 2 mm, and more preferably about 50 μm to 1 mm.

  Further, the configuration of the positive electrode active material layer 12 is not particularly limited as long as it includes at least the positive electrode active material. For example, the positive electrode active material layer 12 may include other materials such as a conductive material, a thickener, and a binder in addition to the positive electrode active material.

  The conductive material is not particularly limited as long as it is an electron conductive material that does not adversely affect the battery performance of the positive electrode 10. For example, carbon black, acetylene black, ketjen black, graphite (natural graphite, artificial graphite), carbon fiber, etc. These carbonaceous materials or conductive metal oxides can be used. Among these, as the conductive material, carbon black and acetylene black are preferable from the viewpoints of electron conductivity and coatability.

  As the thickener, for example, polyethylene glycols, celluloses, polyacrylamides, poly N-vinyl amides, poly N-vinyl pyrrolidones and the like can be used. Among these, as the thickener, celluloses such as polyethylene glycols and carboxymethyl cellulose (CMC) are preferable, and CMC is particularly preferable.

  The binder serves to bind the active material particles and the conductive material particles, for example, a fluorine-based polymer such as polyvinylidene fluoride (PVDF), polyvinylpyridine, polytetrafluoroethylene, or a polyolefin such as polyethylene or polypropylene. A polymer, styrene butadiene rubber, or the like can be used.

  Examples of the solvent for dispersing the positive electrode active material, the conductive material, the binder, and the like include, for example, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, Organic solvents such as N-dimethylaminopropylamine, ethylene oxide, and tetrahydrofuran can be used.

  The positive electrode 10 described above is obtained by mixing a positive electrode active material, a conductive material, a thickener and a binder, and adding a suitable solvent to form a paste-like positive electrode mixture. It is formed by compressing to dry the electrode and increasing the electrode density as necessary.

  Further, as shown in FIG. 12, the positive electrode 10 has a substantially rectangular shape in plan view. The width W1 in the Y direction of the positive electrode 10 is, for example, about 100 mm, and the length L1 in the X direction is, for example, about 150 mm. Further, in the application region (formation region) of the positive electrode active material layer 12, the width W11 in the Y direction is the same as the width W1 of the positive electrode 10, for example, about 100 mm, and the length L11 in the X direction is, for example, It is about 135 mm.

  As shown in FIGS. 11 to 13, the positive electrode 10 has a surface (conductive layer 14) of the positive electrode current collector 11 without forming the positive electrode active material layer 12 on one end side (end portion) in the X direction. Has an exposed current collector exposed portion (exposed region) 11a. A tab electrode 41 (see FIG. 1) for taking out a current to the outside is electrically connected to the current collector exposed portion 11a. The tab electrode 41 is formed in, for example, a shape having a width of about 30 mm and a length of about 70 mm.

  The negative electrode 20 constituting the electrode group 50 has a configuration in which a negative electrode active material layer 22 is supported on both surfaces of a negative electrode current collector 21, as shown in FIG.

  The negative electrode current collector 21 has a function of collecting the negative electrode active material layer 22.

  In the first embodiment, unlike the positive electrode current collector 11 (see FIG. 11), the negative electrode current collector 21 does not include a resin layer. That is, only the positive electrode current collector 11 (see FIG. 11) has a multilayer structure including a resin layer.

  Specifically, the negative electrode current collector 21 is made of, for example, a metal foil such as copper, nickel, stainless steel, iron, or a nickel plating layer, or an alloy foil made of these alloys, and has a thickness of about 1 μm to about 1 μm. The thickness is 100 μm (for example, about 16 μm). The negative electrode current collector 21 is preferably a metal foil made of copper or a copper alloy from the viewpoint that it is difficult to alloy with lithium, and the thickness is preferably 4 μm or more and 20 μm or less.

  Moreover, the negative electrode current collector 21 has a film shape, a sheet shape, a net shape, a punched or expanded shape, a lath body, a porous body, a foamed body, a formed body of fiber groups, etc. in addition to the foil shape. There may be.

The negative electrode active material layer 22 includes a negative electrode active material that can occlude and release lithium ions. As the negative electrode active material, for example, a material containing lithium or a material capable of occluding and releasing lithium is used. In order to constitute a high energy density battery, it is preferable that the potential for insertion / extraction of lithium is close to the deposition / dissolution potential of metallic lithium. Typical examples thereof include particulate natural graphite or artificial graphite (scale-like, lump-like, fibrous, whisker-like, spherical, pulverized particle-like, etc.). As the negative electrode active material, artificial graphite obtained by graphitizing mesocarbon microbeads, mesophase pitch powder, isotropic pitch powder, or the like may be used. Further, graphite particles having amorphous carbon attached to the surface can also be used. Furthermore, lithium transition metal oxides, lithium transition metal nitrides, transition metal oxides, silicon oxides, and the like can also be used. As the lithium transition metal oxide, for example, when lithium titanate represented by Li ₄ Ti ₅ O ₁₂ is used, the deterioration of the negative electrode 20 is reduced, so that the battery life can be extended.

  The thickness of the negative electrode active material layer 22 is preferably about 20 μm to 2 mm, and more preferably about 50 μm to 1 mm.

  Further, the configuration of the negative electrode active material layer 22 is not particularly limited as long as it includes at least a negative electrode active material. For example, the negative electrode active material layer 22 may include other materials such as a conductive material, a thickener, and a binder in addition to the negative electrode active material. Note that other materials such as a conductive material, a thickening material, and a binder can be the same as the positive electrode active material layer 12 (that can be used for the positive electrode active material layer 12).

  The negative electrode 20 described above is obtained by mixing a negative electrode active material, a conductive material, a thickener and a binder, and adding a suitable solvent to form a paste-like negative electrode mixture. It is formed by compressing to dry the electrode and increasing the electrode density as necessary.

  Further, as shown in FIG. 15, the negative electrode 20 has a substantially rectangular shape in plan view, and is substantially the same size (plane area) as the positive electrode 10 (see FIGS. 12 and 13). Is formed. Specifically, in the first embodiment, the negative electrode 20 has the same width W2 in the Y direction as the width W1 of the positive electrode 10 (see FIG. 12), for example, about 100 mm, and the length in the X direction. L2 is the same as the length L1 of the positive electrode 10 (see FIG. 12), for example, about 150 mm. In addition, in the application region (formation region) of the negative electrode active material layer 22, the width W21 in the Y direction is the same as the width W2 of the negative electrode 20, for example, about 100 mm, and the length L21 in the X direction is, for example, It is about 135 mm.

  14 to 16, the negative electrode 20 is similar to the positive electrode 10 in that the negative electrode active material layer 22 is not formed on one end side (end portion) in the Y direction, and the surface of the negative electrode current collector 21 is formed. The current collector exposed portion (exposed region) 21a is exposed. A tab electrode 42 (see FIG. 2) for taking out current to the outside is electrically connected to the current collector exposed portion 21a. The tab electrode 42 is formed in a shape having a width of about 30 mm and a length of about 70 mm, for example, like the tab electrode 41.

  The separator 30 constituting the electrode group 50 (see FIGS. 3, 4 and 8) is, for example, an electrically insulating synthetic resin fiber, a non-woven fabric such as glass fiber or natural fiber, a woven fabric or a microporous membrane. Can be selected as appropriate. Among these, non-woven fabrics such as polyethylene, polypropylene, polyester, aramid resins, and cellulose resins, and microporous membranes are preferable from the viewpoint of quality stability, and in particular, non-woven fabrics composed of aramid resins, polyester resins, or cellulose resins. A microporous membrane is preferred.

  Further, the separator 30 preferably has a melting point of 200 ° C. or lower so that when heat is generated in the lithium ion secondary battery due to an internal short circuit, the pores of the separator 30 are blocked and ion conduction is blocked. It is preferable to have a melting point higher than that of the resin layer 13 of the current collector 11. For example, the separator 30 is preferably configured so that the thermal contraction rate at 120 ° C. is smaller than that of the resin layer 13 of the positive electrode current collector 11. In addition, for example, the separator 30 is preferably made of a material having a heat shrinkage rate of 1.0% or less at a temperature not higher than the heat deformation temperature of the resin layer 13 of the positive electrode current collector 11. Furthermore, the separator 30 is preferably made of a porous film such as an aramid resin, a polyester resin, or a cellulose resin having a heat shrinkage rate of 180% or less at 180 ° C.

The thickness of the separator 30 is not particularly limited, but is a thickness that can hold a necessary amount of electrolyte and can prevent a short circuit between the positive electrode 10 and the negative electrode 20. Is preferred. Specifically, the separator 30 can have a thickness of 0.02 mm (20 μm) to 0.1 mm (100 μm), for example. The thickness of the separator 30 is preferably about 0.01 mm to 1 mm, and more preferably about 0.02 mm to 0.07 mm. The material constituting the separator 30 is such that the air permeability per unit area (1 cm ² ) is about 0.1 seconds / cm ^{3 to} 500 seconds / cm ³ while maintaining a low battery internal resistance. This is preferable because strength sufficient to prevent an internal short circuit can be secured.

  In addition, also about a separator, a heat-deformation temperature and a heat-shrink rate mean the value obtained by the method similar to the resin layer (resin film) mentioned above. When measuring the heat shrinkage at 120 ° C., heat treatment is performed at 120 ° C., and when measuring the heat shrinkage at 180 ° C., heat treatment is performed at 180 ° C.

  The separator 30 is larger than the application region (formation region) of the positive electrode active material layer 12 and is equivalent to the application region (formation region) of the negative electrode active material layer 22 or the application region (formation) of the negative electrode active material layer 22. (Region) has a larger shape. Specifically, as shown in FIG. 17, the separator 30 is formed in a rectangular shape, and the width W3 in the Y direction is, for example, about 115 mm, and the length L3 in the X direction is, for example, about 160 mm. Yes.

  In the positive electrode 10 and the negative electrode 20, the current collector exposed portion 11a of the positive electrode 10 and the current collector exposed portion 21a of the negative electrode 20 are positioned on opposite sides as shown in FIGS. The separator 30 is interposed between the positive and negative electrodes. At this time, each separator 30 is disposed so as to cover the positive electrode active material layer 12 and the negative electrode active material layer 22, respectively. On the other hand, a region where the separator 30 is not interposed is provided between the current collector exposed portions 11 a of the stacked positive electrodes 10. Similarly, a region where no separator 30 is interposed is provided between the current collector exposed portions 11 a of the stacked positive electrodes 10.

  Here, in the first embodiment, as shown in FIGS. 1, 2, and 7, the metal member 80 described above is disposed between the current collector exposed portions 11 a of the stacked positive electrodes 10. The metal member 80 is configured by folding (folding) a strip-shaped metal foil into a zigzag shape. For this reason, the metal member 80 includes a bent portion 81 that is a portion where the metal foil is bent, and a flat portion 82 that is a relatively flat portion provided between the bent portions 81. The metal member 80 is connected to the laminated positive electrode 10 so that the flat portion 82 of the metal member 80 is located in a region between the current collector exposed portions 11a of the positive electrode 10 where the separator 30 is not interposed. ing.

  Moreover, the said metal member 80 is comprised so that it may extend in a Y direction, as shown to FIG. 1 and FIG. 2, and is distribute | arranged along the collector exposed part 11a. Furthermore, as shown in FIGS. 7, 8, and 10, one flat portion 82 of the metal member 80 is located between the current collector exposed portions 11a. Therefore, as shown in FIGS. 2 and 7, the bent portion 81 of the metal member 80 is outside the positive electrode 10 (the positive electrode current collector 11) (on the side end side (Y direction side) of the positive electrode 10). It is in the state located in. The metal member 80 is not only between the current collector exposed portions 11a, but also on the outermost current collector (outside of the outermost positive electrode 10) in the electrode group 50 (stacked positive electrode 10). The flat portion 82 is also located on the layer 14).

  Thus, in the first embodiment, the plurality of positive electrodes 10 are stacked with the flat portion 82 of the metal member 80 having a zigzag folded shape sandwiched between the current collector exposed portions 11a. Further, the metal member 80 is electrically connected to the conductive layer 14 of each positive electrode current collector 11 by being disposed in a region between the current collector exposed portions 11a of the positive electrode 10 where the separator 30 is not interposed. Has been. Accordingly, in the first embodiment, all the stacked positive electrodes 10 (the conductive layer 14 of the positive electrode current collector 11) are electrically connected to each other via the metal member 80. In the first embodiment, all the stacked positive electrodes 10 (the conductive layer 14 of the positive electrode current collector 11) are electrically connected to each other by one metal member 80 having a zigzag folded shape.

  The metal member 80 (metal foil) attached to the positive electrode 10 is preferably made of the same metal material (for example, aluminum or aluminum alloy) as the conductive layer 14 of the positive electrode current collector 11. The thickness of the metal member 80 (metal foil) is not particularly limited, but is preferably about 0.02 mm to about 0.5 mm, for example.

  In the positive electrode 10 of the electrode group 50, the tab electrode 41 described above is disposed on the outermost positive electrode 10 (metal member 80) in a state where the metal member 80 is disposed between the current collector exposed portions 11a as described above. It is fixed by welding. Specifically, as shown in FIGS. 1 and 2, the tab electrode 41 is welded and fixed to a substantially central portion in the width direction (Y direction) of the positive electrode current collector 11 (positive electrode 10). As a result, all the stacked positive electrodes 10 (all the conductive layers 14) are fixed to the tab electrode 41 by welding and are electrically connected to the tab electrode 41.

  As shown in FIGS. 3 and 4, the plurality of negative electrodes 20 are stacked so that the current collector exposed portions 21 a are aligned, as with the positive electrode 10. The tab electrode 42 is fixed by welding to the outermost negative electrode 20 (negative electrode current collector 21). Thereby, all the laminated negative electrodes 20 are welded and fixed to the tab electrode 42 and are electrically connected to the tab electrode 42. The tab electrode 42 is welded and fixed to a substantially central portion in the width direction (Y direction) of the negative electrode current collector 21 (negative electrode 20).

  The welding of the tab electrodes 41 and 42 is preferably ultrasonic welding, but may be other than ultrasonic welding. For example, laser welding, resistance welding, spot welding, or the like may be used. However, in the case where the tab electrode 41 is welded to the positive electrode current collector 11 with the resin layer 13 interposed therebetween, the resin layer 13 may be dissolved by a method of joining by applying heat such as laser welding, resistance welding, or spot welding. There is. Therefore, it is preferable to use ultrasonic welding without applying heat for the welding of the tab electrode 41. Also for the connection (fixation) of the metal member 80, ultrasonic welding is preferable, similarly to the welding of the tab electrodes 41 and 42. However, as described above, other than ultrasonic welding, for example, laser welding, resistance welding, spot welding, or the like may be used. Further, the connection (fixation) of the metal member 80 may be performed simultaneously with the welding of the tab electrode 41.

  The tab electrode 41 connected to the positive electrode 10 is preferably made of aluminum, and the tab electrode 42 connected to the negative electrode 20 is preferably made of copper. The tab electrodes 41 and 42 are preferably made of the same material as the current collector, but may be made of different materials. Further, the tab electrode 41 connected to the positive electrode 10 and the tab electrode 42 connected to the negative electrode 20 may be made of the same material or different materials. In addition, the tab electrodes 41 and 42 are preferably welded to substantially the center portion in the width direction of the positive electrode current collector 11 and the negative electrode current collector 21 as described above, but are fixed to the regions other than the center portion by welding. May be.

  The nonaqueous electrolytic solution enclosed with the electrode group 50 in the outer container 100 (see FIG. 3) is not particularly limited, but examples of the solvent include ethylene carbonate (EC), propylene carbonate, butylene carbonate, diethyl Esters such as carbonate (DEC), dimethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, dioxolane, diethyl ether, dimethoxyethane, diethoxyethane, methoxyethoxyethane, Polar solvents such as dimethyl sulfoxide, sulfolane, methyl sulfolane, acetonitrile, methyl formate, and methyl acetate can be used. These solvents may be used alone, or two or more kinds may be mixed and used as a mixed solvent.

The nonaqueous electrolytic solution may contain an electrolyte supporting salt. Examples of the electrolyte supporting salt include LiClO ₄ , LiBF ₄ (lithium borofluoride), LiPF ₆ (lithium hexafluorophosphate), LiCF ₃ SO ₃ (lithium trifluoromethanesulfonate), LiF (lithium fluoride), LiCl Examples thereof include lithium salts such as (lithium chloride), LiBr (lithium bromide), LiI (lithium iodide), LiAlCl ₄ (lithium tetrachloride aluminate). These may be used singly or in combination of two or more.

  The concentration of the electrolyte supporting salt is not particularly limited, but is preferably 0.5 mol / L to 2.5 mol / L, and more preferably 1.0 mol / L to 2.2 mol / L. When the concentration of the electrolyte support salt is less than 0.5 mol / L, the carrier concentration for carrying charges in the non-aqueous electrolyte is lowered, and the resistance of the non-aqueous electrolyte may be increased. Further, when the concentration of the electrolyte supporting salt is higher than 2.5 mol / L, the dissociation degree of the salt itself is lowered, and there is a possibility that the carrier concentration in the non-aqueous electrolyte does not increase.

  As shown in FIGS. 3 and 9, the exterior container 100 that encloses the electrode group 50 is a large flat rectangular container, and an exterior can 60 that houses the electrode group 50 and the like, and a sealing plate that seals the exterior can 60 70. Further, a sealing plate 70 is attached to the outer can 60 containing the electrode group 50 by, for example, laser welding.

  The outer can 60 is formed, for example, by deep drawing or the like on a metal plate, and is formed in a substantially box shape having a bottom surface portion 61 and a side wall portion 62. As shown in FIG. 3, an opening 63 for inserting the electrode group 50 is provided at one end of the outer can 60 (the side opposite to the bottom surface portion 61). The outer can 60 is formed in such a size that the electrode group 50 can be accommodated so that the electrode surface thereof faces the bottom surface portion 61.

  As shown in FIGS. 3 and 9, the outer can 60 has an electrode terminal 64 (for example, a positive electrode terminal) formed on a side wall 62 on one side (short side) in the X direction. An electrode terminal 64 (for example, a negative electrode terminal) is formed on the side wall portion 62 on the other side (short side) in the direction. In addition, a liquid injection hole 65 for injecting a nonaqueous electrolytic solution is formed in the side wall 62 of the outer can 60. The liquid injection hole 65 is formed in a size of φ2 mm, for example. A safety valve 66 for releasing the battery internal pressure is formed in the vicinity of the liquid injection hole 65.

  Further, a folded portion 67 is provided on the periphery of the opening 63 of the outer can 60, and the sealing plate 70 is fixed to the folded portion 67 by welding.

  The outer can 60 and the sealing plate 70 can be formed using, for example, a metal plate such as iron, stainless steel, and aluminum, or a steel plate obtained by applying nickel plating to iron. Since iron is an inexpensive material, it is preferable from the viewpoint of price, but in order to ensure long-term reliability, it is preferable to use a metal plate made of stainless steel, aluminum or the like, or a steel plate with nickel plated on iron. More preferred. The thickness of the metal plate can be, for example, about 0.4 mm to about 1.2 mm (for example, about 1.0 mm).

  The electrode group 50 described above is housed in the outer can 60 such that the positive electrode 10 and the negative electrode 20 face the bottom surface portion 61 of the outer can 60. In the accommodated electrode group 50, the current collector exposed portion 11a of the positive electrode 10 and the current collector exposed portion 21a of the negative electrode 20 are electrically connected to the electrode terminal 64 of the outer can 60 via the tab electrodes 41 and 42, respectively. It is connected to the.

  In addition, the nonaqueous electrolytic solution is injected, for example, under reduced pressure from the liquid injection hole 65 after the opening 63 of the outer can 60 is sealed by the sealing plate 70. And after installing the metal ball | bowl (not shown) of the diameter substantially the same as the liquid injection hole 65 in the liquid injection hole 65, the liquid injection hole 65 is sealed by resistance welding, laser welding, etc.

  In the lithium ion secondary battery according to the first embodiment, as described above, the metal member 80 folded in a zigzag manner is disposed between the current collector exposed portions 11a of the positive electrode 10 so that the metal member 80 is interposed therebetween. Thus, the conductive layers 14 of the current collector in the plurality of positive electrodes 10 can be electrically connected to each other. For this reason, even when a current collector having a multilayer structure (positive electrode current collector 11) is used, conduction between the plurality of stacked electrodes can be achieved. Thereby, the tab electrode 41 can be electrically connected to all of the plurality of stacked electrodes (positive electrode 10). Therefore, since the deterioration of battery performance can be suppressed, the performance of the lithium ion secondary battery can be fully utilized.

  Further, in the first embodiment, as described above, by using a current collector having a multilayer structure as the positive electrode current collector 11, for example, when abnormal heat generation occurs in an overcharged state or a high temperature state, the positive electrode current collector 11 Since the resin layer 13 of the current collector 11 is melted and the electrode (positive electrode 10) is damaged, the current can be cut. Thereby, since the temperature rise inside a battery can be suppressed, it can prevent that abnormal states, such as ignition, arise.

  In the first embodiment, by providing the metal member 80, for example, when the tab electrode 41 is connected to the electrode (positive electrode 10) by ultrasonic welding, the tab electrode 41 and the electrode (positive electrode 10) are in contact with each other. Resistance and contact resistance between electrodes can be reduced. Thereby, the tab electrode 41 can be firmly connected to the electrode (positive electrode 10). In addition, by firmly connecting the tab electrode 41 to the electrode (positive electrode 10), it is possible to suppress a decrease in battery capacity due to an increase in contact resistance. Further, as shown in FIG. 18, a plurality of tab electrodes 41 may be provided, and the tab electrodes 41 may be connected to a plurality of positions of the electrode (positive electrode 10).

  Further, by configuring the metal member 80 from a metal foil, the metal member 80 can be easily disposed between the current collector exposed portions 11a. Further, when the plurality of electrodes 5 (positive electrodes 10) are electrically connected to each other, the use of the metal member 80 can facilitate the conduction between the electrodes.

  In the first embodiment, the metal member 80 is configured in a zigzag shape that is bent outside the positive electrode 10, whereby the conductive layers 14 in the plurality of positive electrodes 10 can be easily connected to each other via the metal member 80. Can be electrically connected.

  In the first embodiment, the metal member 80 is fixed to the positive electrode 10 (the positive electrode current collector 11), and the tab electrode 41 is connected to the metal member 80, whereby the tab electrode 41 and the positive electrode 10 are electrically connected. Can be easily taken.

  Further, in the first embodiment, by forming the resin layer 13 of the positive electrode current collector 11 from a resin material having a melting temperature of 200 ° C. or less, for example, abnormal heat generation occurs in an overcharged state or a high temperature state. In this case, since the electrode can be easily damaged, it is possible to effectively prevent an abnormal state such as ignition. For this reason, the safety | security of a lithium ion secondary battery can be improved effectively. It is more effective if the resin layer 13 of the positive electrode current collector 11 is made of a thermoplastic resin having a thermal shrinkage rate at 120 ° C. of 1.5% or more in either the longitudinal direction or the transverse direction. In addition, since it is possible to prevent an abnormal state such as ignition, the safety of the lithium ion secondary battery can be improved more effectively.

  Moreover, if the resin layer 13 of the positive electrode current collector 11 is made of a polyolefin resin, polyvinyl chloride, or a composite material thereof, the safety of the lithium ion secondary battery can be easily improved.

  In the first embodiment, the separator 30 is made of a resin material having a heat shrinkage rate of 1.0% or less at a temperature equal to or lower than the heat deformation temperature of the resin layer 13, so that it can be used in an overcharged state or a high temperature state. When abnormal heat generation occurs, the electrode (positive electrode 10) can be easily damaged. That is, by making the thermal deformation temperature of the separator 30 higher than the thermal deformation temperature of the resin layer 13, the resin layer 13 constituting the positive electrode current collector 11 can be blown before the shutdown function of the separator 30 is activated. it can. Thereby, the current interruption effect by the resin layer 13 and the separator 30 makes it possible to interrupt the current in two stages, so that the safety of the lithium ion secondary battery can be further improved.

  If the thermal contraction rate at 180 ° C. of the separator 30 is 1.0% or less, an internal short circuit caused by thermal contraction of the separator 30 when abnormal heat generation occurs in an overcharged state or a high temperature state. Since generation | occurrence | production of (the internal short circuit of the battery produced in an electrode edge part) can be suppressed, it can suppress that a rapid temperature rise arises. For this reason, since generation | occurrence | production of the internal short circuit (internal short circuit of the battery produced in an electrode edge) resulting from the thermal contraction of the separator 30 when heat_generation | fever arises inside a battery can be suppressed, rapid temperature rise It can be suppressed from occurring. As a result, the safety of the lithium ion secondary battery can be further improved. That is, with this configuration, the separator 30 can be prevented from melting / fluidizing even at a temperature of 180 ° C., so that there is a disadvantage that the pores of the separator 30 increase due to melting / fluidization. Can be suppressed. For this reason, when the inside of the battery reaches 180 ° C., even if the electrode (positive electrode 10) is not damaged for some reason, the short-circuited portion of the positive and negative electrodes is caused by the large hole in the separator 30. The inconvenience of spreading can be suppressed.

(Modification of the first embodiment)
FIG. 19 is a cross-sectional view schematically showing a part of a lithium ion secondary battery according to a modification of the first embodiment. FIG. 19 shows a diagram corresponding to FIG. 7 of the first embodiment.

  In the modification of the first embodiment, as shown in FIG. 19, all the stacked positive electrodes 10 (the conductive layers 14 of the positive electrode current collector 11) are electrically connected to each other by a plurality of metal members 80 having a zigzag shape. It is connected. As described above, the number of metal members 80 disposed between the current collector exposed portions 11a of the positive electrode 10 is not limited to one, and may be plural.

  Also in this case, a configuration in which a plurality of tab electrodes 41 are provided and these tab electrodes 41 are connected to a plurality of positions of the electrodes (positive electrode 10) can be adopted. For example, in order to increase the contact area between the tab electrode 41 and the metal member 80, the tab electrode 41 can be connected to the metal member 80 at each of the upper part and the lower part of the laminate. Such a configuration can also be applied to the first embodiment.

  Other configurations in the modified example of the first embodiment are the same as those in the first embodiment. The effect of the modification of the first embodiment is the same as that of the first embodiment.

(Second Embodiment)
FIG. 20 is a plan view schematically showing a part of an electrode group (positive electrode) used in the lithium ion secondary battery according to the second embodiment of the present invention. FIG. 21 is a diagram schematically showing a cross section taken along line A2-A2 of FIG. 22 and 23 are views schematically showing a metal member of the lithium ion secondary battery according to the second embodiment of the present invention. Next, with reference to FIGS. 20-23, the lithium ion secondary battery by 2nd Embodiment of this invention is demonstrated. In addition, in each figure, the same code | symbol is attached | subjected to a corresponding component, and the overlapping description is abbreviate | omitted suitably.

  In the second embodiment, as shown in FIGS. 20 and 21, the metal member 80 described above is disposed between the current collector exposed portions 11 a of the stacked positive electrodes 10. In the second embodiment, unlike the first embodiment, two flat portions 82 of the metal member 80 are positioned between the current collector exposed portions 11a.

  Specifically, as shown in FIG. 22 and FIG. 23, the metal member 80 is folded in a zigzag manner so that the adjacent flat portions 82 are in contact with each other, and the two flat portions overlap each other. 82 is disposed between the current collector exposed portions 11 a of the positive electrode 10. Further, as shown in FIG. 20, the bent portion 81 of the metal member 80 is configured to be located outside the positive electrode 10 (positive electrode current collector 11) (on the side end side (Y direction side) of the positive electrode 10). ing.

  Other configurations of the second embodiment are the same as those of the first embodiment. The effect of the second embodiment is the same as that of the first embodiment.

(Modification of the second embodiment)
FIG. 24 is a plan view schematically showing a part of an electrode group (positive electrode) used in a lithium ion secondary battery according to a modification of the second embodiment. FIG. 25 is a diagram schematically showing a cross section taken along line A3-A3 of FIG.

  In the modification of the second embodiment, as shown in FIGS. 24 and 25, in the configuration of the second embodiment, one bent portion 81 a (81) of the metal member 80 is exposed to the current collector of the positive electrode 10. It is the structure arranged between the parts 11a. Thus, even when one bent portion 81a (81) of the metal member 80 is disposed between the current collector exposed portions 11a, the same effect as in the second embodiment can be obtained.

  Other configurations in the modified example of the second embodiment are the same as those in the second embodiment.

(Third embodiment)
FIG. 26 is a plan view schematically showing a part of an electrode group (positive electrode) used in the lithium ion secondary battery according to the third embodiment of the present invention. FIG. 27 is a cross-sectional view schematically showing a metal member of the lithium ion secondary battery according to the third embodiment of the present invention. FIG. 28 is a diagram schematically showing a cross section taken along line A4-A4 of FIG. Next, with reference to FIGS. 26-28, the lithium ion secondary battery by 3rd Embodiment of this invention is demonstrated. In addition, in each figure, the same code | symbol is attached | subjected to a corresponding component, and the overlapping description is abbreviate | omitted suitably.

  In the third embodiment, as shown in FIGS. 26 to 28, two flat portions 82 of the metal member 80 are positioned between the current collector exposed portions 11a as in the second embodiment. Has been. In the third embodiment, as shown in FIG. 28, one bent portion 81 a (81) of the metal member 80 is disposed between the current collector exposed portions 11 a of the positive electrode 10, while the metal member 80. The other bent portion 81b (81) of the positive electrode 10 is configured to be located on the end side (outside) in the X direction of the positive electrode 10. That is, in the third embodiment, one bent portion 81 a (81) of the metal member 80 is inserted between the positive electrode current collectors 11 from the end side in the X direction of the positive electrode 10. Yes.

  Other configurations of the third embodiment are the same as those of the first and second embodiments. The effects of the third embodiment are the same as those of the first and second embodiments.

(Modification of the third embodiment)
FIG. 29 is a plan view schematically showing a part of an electrode group (positive electrode) used in a lithium ion secondary battery according to a modification of the third embodiment.

  In the modification of the third embodiment, as shown in FIG. 29, in the configuration of the third embodiment, the metal member 80 is attached to the current collector exposed portion 11a of the positive electrode 10 so as to protrude in the X direction. ing. The tab electrode 41 is welded and fixed to the metal member 80 in a region that does not overlap the positive electrode 10 (current collector exposed portion 11a).

  Other configurations in the modified example of the third embodiment are the same as those in the third embodiment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first to third embodiments (including modifications), an example in which the present invention is applied to a lithium ion secondary battery that is an example of a non-aqueous secondary battery has been described, but the present invention is not limited thereto. First, the present invention may be applied to non-aqueous secondary batteries other than lithium ion secondary batteries. The present invention can also be applied to non-aqueous secondary batteries that will be developed in the future.

  Moreover, in the said 1st-3rd embodiment (a modification is included), although the example using the metal member which consists of metal foil as an example of the electroconductive member bent in the zigzag shape was shown, this invention is not limited to this. The conductive member may be made of a conductive material other than a metal material. For example, the conductive member may be composed of a conductive resin such as a conductive plastic, or may be composed of a member having a metal film or the like formed on the surface of the resin film. Note that the conductive member may have a shape other than the foil shape as long as the conductive member can be folded in a zigzag shape and disposed between the electrodes. For example, a sheet form, a fiber form, etc. may be sufficient.

  Moreover, in the said 1st-3rd embodiment (a modification is included), although the example which used the film-form resin layer for the resin layer (insulating layer) of the electrical power collector was shown, this invention is not limited to this. In addition to the film shape, for example, a fibrous resin layer may be used. As a fibrous resin layer, the layer which consists of a woven fabric or a nonwoven fabric etc. is mentioned, for example.

  Moreover, in the said 1st-3rd embodiment (a modification is included), although the example which comprised the positive electrode electrical power collector to the electrical power collector which has a three-layer structure was shown, this invention is not restricted to this, The said The current collector may have a multilayer structure other than the three-layer structure. For example, a multilayer structure of three or more layers may be formed by forming a plating layer or the like on a metal foil.

  In the first to third embodiments (including modifications), the positive electrode side current collector is shown in a multilayer structure including a resin layer and a conductive layer. However, the present invention is not limited to this. Alternatively, the current collector on the negative electrode side may have a multilayer structure including a resin layer and a conductive layer. For example, both the positive electrode and the negative electrode may be formed using a current collector having a multilayer structure (three-layer structure), or one of the positive electrode and the negative electrode has a multilayer structure (three-layer structure). You may form using. When one of the positive electrode and the negative electrode is formed using a current collector having a multilayer structure (three-layer structure), the positive electrode side is formed using a current collector having a multilayer structure (three-layer structure). Is preferred.

  Further, when the current collector on the negative electrode side has a multilayer structure, the conductive layer is preferably made of copper or a copper alloy. Specifically, for example, a copper foil or a copper alloy foil having a thickness of about 2 μm to about 15 μm can be used as the conductive layer. The conductive layer of the negative electrode current collector may be other than copper or a copper alloy, and may be composed of, for example, nickel, stainless steel, iron, or an alloy thereof. The resin layer of the negative electrode current collector can be, for example, the same as the resin layer of the positive electrode current collector (that can be used for the resin layer of the positive electrode current collector).

  In addition, when the current collector on the negative electrode side is configured in a multilayer structure, the metal bent in a zigzag manner is the same as the positive electrode (positive electrode current collector) shown in the first to third embodiments (including modifications). A plurality of stacked electrodes (negative electrode) and a tab electrode are configured to be electrically connected using a member (metal foil). In this case, the metal member is preferably made of copper or a copper alloy.

  Moreover, in the said 1st-3rd embodiment (a modification is included), although the example which used the flat rectangular container for the exterior container which accommodates an electrode group was shown, this invention is not limited to this, The shape of an exterior container May be other than a flat square. For example, the outer container may be a thin flat tube type, a cylindrical type, a rectangular tube type, or the like. However, in the case of a large-sized lithium ion secondary battery, since it is often used as an assembled battery, it is preferably a thin flat type or a square type. Further, the outer container may be an outer container using a laminated sheet, for example, in addition to a metal can.

  In the first to third embodiments (including modifications), the positive electrode (positive electrode active material layer) and the negative electrode (negative electrode active material layer) are configured to have the same size. The present invention is not limited to this, and the positive electrode and the negative electrode may have different sizes. For example, the negative electrode (negative electrode active material layer) may be configured to be larger than the positive electrode (positive electrode active material layer), or the positive electrode (positive electrode active material layer) may be configured to be larger than the negative electrode (negative electrode active material layer). It may be configured to be larger. When the positive electrode and the negative electrode are configured to have different sizes, the negative electrode (negative electrode active material layer) is preferably configured to be larger than the positive electrode (positive electrode active material layer). With this configuration, the positive electrode active material layer formation region (positive electrode active material region) is covered with a large area negative electrode active material layer formation region (negative electrode active material region), thereby allowing for stacking deviation. The range can be expanded.

  In addition, in the said 1st-3rd embodiment (a modification is included), about the magnitude | size, shape, etc. of an exterior container, it can change variously. Further, the shape, size, number of sheets used, etc. of the electrodes (positive electrode, negative electrode) can be changed as appropriate. Furthermore, the shape and dimensions of the separator can be changed as appropriate. Examples of the shape of the separator include various shapes such as a rectangle such as a square or a rectangle, a polygon, and a circle.

  Moreover, in the said 1st-3rd embodiment (a modification is included), although the example which formed the active material layer on both surfaces of the electrical power collector was shown, this invention is not restricted to this, On the single surface of an electrical power collector. Only the active material layer may be formed. Moreover, you may comprise so that the electrode (positive electrode, negative electrode) which formed the active material layer only in the single side | surface of a collector may be included in a part of electrode group.

  Moreover, in the said 1st-3rd embodiment (a modification is included), although the example which used non-aqueous electrolyte as an electrolyte of a lithium ion secondary battery was shown, this invention is not limited to this, Non-aqueous electrolysis For example, a gel electrolyte, a polymer solid electrolyte, an inorganic solid electrolyte, a molten salt, or the like other than the liquid may be used as the electrolyte.

  Note that embodiments obtained by appropriately combining the techniques disclosed above are also included in the technical scope of the present invention.

5 Electrode 10 Positive electrode 11 Positive electrode current collector (current collector)
11a Current collector exposed portion 12 Positive electrode active material layer 13 Resin layer (insulating layer)
DESCRIPTION OF SYMBOLS 14 Conductive layer 20 Negative electrode 21 Negative electrode collector 21a Current collector exposed part 22 Negative electrode active material layer 30 Separator 41, 42 Tab electrode 50 Electrode group 60 Exterior can 61 Bottom face part 62 Side wall part 63 Opening part 64 Electrode terminal 65 Injection hole 66 Safety valve 67 Folding part 70 Sealing plate 80 Metal member (conductive member)
81 Folded part 82 Flat part 100 Outer container

Claims (16)

A plurality of electrodes including a current collector having a multilayer structure in which an insulating layer is sandwiched between conductive layers; and an active material layer formed on the current collector;
A conductive member electrically connecting the plurality of electrodes to each other;
A tab electrode electrically connected to the electrode,
Each of the plurality of electrodes has a current collector exposed portion in which the conductive layer is exposed without forming the active material layer,
The non-aqueous secondary battery, wherein the conductive member is folded in a zigzag manner and disposed between the current collector exposed portions of the plurality of electrodes.   The non-aqueous secondary battery according to claim 1, wherein the conductive member is made of a metal foil.   The non-aqueous secondary battery according to claim 1, wherein the conductive member has a zigzag shape that is bent outside the electrode. The current collector exposed portion is provided at an end of the electrode,
The non-aqueous secondary battery according to claim 1, wherein the conductive member is disposed along the current collector exposed portion. The conductive member is fixed to the current collector,
The non-aqueous secondary battery according to claim 1, wherein the tab electrode is connected to the conductive member.   The non-aqueous secondary battery according to claim 1, wherein the conductive layer and the conductive member of the current collector are made of the same metal material. The electrode includes a positive electrode and a negative electrode,
3. The non-aqueous secondary battery according to claim 1, wherein at least one of the positive electrode and the negative electrode is formed using the current collector having a multilayer structure. 4. When the positive electrode is formed using the current collector having a multilayer structure, the conductive layer of the current collector in the positive electrode is made of aluminum,
The said negative electrode is formed using the said collector which has a multilayer structure, The said conductive layer of the collector in the said negative electrode is comprised from copper, It is characterized by the above-mentioned. Non-aqueous secondary battery.   The non-aqueous secondary battery according to claim 1, wherein the insulating layer of the current collector is made of a resin material having a melting temperature of 200 ° C. or less.   The insulating layer of the current collector is made of a thermoplastic resin having a thermal shrinkage rate at 120 ° C. of 1.5% or more in either the longitudinal direction or the transverse direction. Or the non-aqueous secondary battery of 2.   The non-aqueous secondary battery according to claim 1, wherein the insulating layer of the current collector is made of a film-like or fibrous resin.   The insulating layer of the current collector is made of a resin containing any of polyolefin resins, a resin containing any of polystyrene, polyvinyl chloride, or polyamide, or a composite material thereof. The nonaqueous secondary battery according to 1 or 2. The electrode includes a positive electrode and a negative electrode, and further includes a separator disposed between the positive electrode and the negative electrode,
The non-aqueous secondary battery according to claim 1, wherein the separator has a higher heat deformation temperature than the insulating layer.   The non-aqueous secondary battery according to claim 13, wherein the separator is made of a material having a heat shrinkage rate of 1.0% or less at a temperature equal to or lower than a heat deformation temperature of the insulating layer.   The non-aqueous secondary battery according to claim 13, wherein the separator has a thermal shrinkage rate at 180 ° C. of 1.0% or less.   The non-aqueous secondary battery according to claim 13, wherein the separator includes any one of an aramid resin, a polyester resin, and a cellulose resin.

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