JP2015072836A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack preventing the generation of heat in a power generation element even if being stuck with a nail, and also preventing heat generated at the outside from being conducted to a power generation element.SOLUTION: In a battery pack 1 of the present invention, at least some stacked batteries 5 among a plurality of stacked batteries 5 are connected in series. A positive electrode conductive material 18 and a negative electrode conductive material 19 which are electrically connected to other electronic apparatus for charging/discharging are stacked on a power generation element 10 via an outer packaging body 20 at an external discharge part 30 that is an outside of the outer packaging body 20 of at least one stacked battery 5 among the plurality of stacked batteries 5, and an insulating member 31 is disposed between the positive electrode conductive material 18 and the negative electrode conductive material 19 at the external discharge part 30.

Description

  The present invention relates to an assembled battery.

  In recent years, the development of electric vehicles (EVs) and hybrid electric vehicles (HEVs) has been promoted against the background of the increasing environmental protection movement. As these motor driving power sources, motor driving electric devices such as secondary batteries that can be repeatedly charged and discharged are suitable. In particular, lithium ion secondary batteries that can be expected to have high capacity and high output are attracting attention, and are currently being developed rapidly.

  A lithium ion secondary battery as an electrical device is configured, for example, by sealing a power generation element with an exterior body. The power generation element includes a positive electrode, a negative electrode, and a separator. In the positive electrode, an electrode material including a positive electrode active material and a binder is formed on the surface of the current collector. In the negative electrode, an electrode material containing a negative electrode active material and a binder is formed on the surface of the current collector.

  The lithium ion secondary battery as described above is desired to have a higher capacity. Along with this, the amount of chemical energy stored in the lithium ion secondary battery increases, so ensuring safety is more important.

  Therefore, generally, an external destructive test for evaluating safety when a lithium ion secondary battery is externally destroyed is performed. One example of the external destructive test is a nail penetration test. In the nail penetration test, conductive nails are pierced in the thickness direction of a flat outer casing to penetrate the battery and observe phenomena such as temperature rise, smoke, and ignition when an internal short circuit occurs in the power generation element. It is a test to do.

  Normally, when an internal short circuit occurs in the power generation element due to nail penetration, a large current flows through the power generation element. At this time, Joule heat is generated and the temperature rises. In addition, instantaneous spark may occur at a location where an internal short circuit has occurred, and heat generation of the positive electrode active material may occur due to these heat generation.

  In order to prevent such excessive heat generation, in Patent Document 1, an insulating layer is provided between the separator and the negative electrode in the exterior. As a result, when the nail penetrates the power generation element, the fibers of the insulating layer are engulfed to become electric resistance, and the nail is discharged to the outside before penetrating the power generation element. Therefore, Joule heat based on the internal short circuit is suppressed.

JP 2008-53196 A

  However, even if the configuration described in the cited document 1 is used, a battery having a high output voltage, such as an assembled battery in which a plurality of batteries are electrically connected in series, has a large current when discharged to the outside. Flow and spark are generated, and the heat generated at this time is transmitted to the power generation element. As a result, deterioration of the material in the power generation element is promoted, and the battery function may be lost.

  The present invention has been made in view of the above circumstances, and even if a nail is stabbed, an assembled battery that suppresses heat generated in the power generation element and also prevents conduction of heat generated outside to the power generation element. The purpose is to provide.

  The present invention that achieves the above object is an assembled battery in which at least some of the plurality of stacked batteries are connected in series. In the stacked battery, a positive electrode having a positive electrode active material layer formed on both sides of a current collector and a negative electrode having a negative electrode active material layer formed on both sides of the current collector are alternately stacked via separators. A power generation element; an exterior body that houses the power generation element; a positive electrode conductive material that is electrically connected to the power generation element via the positive electrode current collector and is led out of the exterior body; and the negative electrode A negative electrode conductive material that is electrically connected to the power generation element via the current collector and led out of the exterior body, and is electrically connected to other electronic devices for charging and discharging. The positive electrode conductive material and the negative electrode conductive material that are connected to the outer periphery of at least one of the plurality of stacked batteries is connected to the power generation element through the exterior body. An insulating member having an insulating property is formed by laminating to form an external discharge part. In the external discharge part is disposed between the positive Gokushirube material and the anode electrical material.

  According to the present invention, the insulating member is provided between the positive electrode conductive material and the negative electrode conductive material that are electrically connected to other electronic devices for charging and discharging. At this time, the positive electrode conductive material, the negative electrode conductive material, and the insulating member are integrally laminated on the upper portion of the exterior body. By having such a structure, even when a nail is pierced into the battery, no large current flows in the power generation element, so Joule heat based on an internal short circuit does not occur. In addition, the heat generated by the spark outside the exterior body is insulated from the exterior body, and therefore is not easily transmitted to the power generation element. Thus, the battery function is not lost by nail penetration, and safety is ensured.

It is a schematic sectional drawing which shows typically the whole structure of the battery which concerns on this embodiment. It is a figure which shows the modification 1 of an external discharge part. It is a figure which shows the modification 2 of an external discharge part. It is a figure which shows the modification 3 of an external discharge part. It is a figure which shows the modification 4 of an external discharge part. It is a figure which shows the modification 5 of an external discharge part.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

<Battery 1>
FIG. 1 is a schematic cross-sectional view schematically showing the overall structure of the assembled battery according to the present embodiment. As shown in FIG. 1, the assembled battery 1 has a structure in which a plurality of batteries 5 are electrically connected in series. In the case of the assembled battery 1 (not shown), the batteries 5 are stacked in a row as shown in FIG. The assembled battery 1 has a structure in which an external discharge unit 30 is disposed on the uppermost part of the plurality of stacked batteries 5. In the illustrated example, three batteries 5 are connected in series. However, the present invention is not limited to this, and there may be two or four or more as long as there are a plurality of batteries.

  Each battery 5 has a structure in which a power generation element 10 that charges and discharges is sealed inside an exterior body 20.

  The power generation element 10 is configured by laminating a plurality of electrodes 11 and 12 and a separator 13.

  Each of the electrodes 11 and 12 has polarity, and hereinafter, the positive electrode is referred to as a positive electrode 11 and the negative electrode is referred to as a negative electrode 12. In the example shown in the figure, positive electrodes 11 and negative electrodes 12 are alternately stacked via separators 13, and single cells composed of a pair of positive electrodes 11 and negative electrodes 12 are electrically connected in parallel. Therefore, the battery 5 of the present embodiment is a battery having a structure called a so-called stacked type (hereinafter referred to as “stacked battery”).

  The positive electrode 11 has a positive electrode active material layer 15 formed on both surfaces of a positive electrode current collector 14. The negative electrode 12 has a negative electrode active material layer 17 formed on both surfaces of a negative electrode current collector 16. In the example shown in FIG. 1, the two positive electrodes 11 and the three negative electrodes 12 are alternately stacked. However, the present invention is not limited to this and may be adjusted according to a desired output voltage. .

  The positive electrode current collector 14 and the negative electrode current collector 16 are constituted by a current collector foil containing a polymer material and a conductive material having conductivity. For example, the positive electrode current collector 14 and the negative electrode current collector 16 may have a structure in which a conductive material is disposed on a current collector foil, or a structure in which a conductive material is sandwiched between two current collector foils. Here, the polymer material does not necessarily have conductivity, but the current collector foil as a whole must have conductivity in order to function as a current collector foil. Therefore, when the polymer material does not have conductivity, the current collector foil naturally includes a conductive filler (conductive particles) having conductivity in addition to the polymer material.

  The conductive filler is selected from materials that have conductivity but do not have conductivity with respect to ions used as a charge transfer medium. Of course, the conductive filler must be selected from materials that can withstand the applied positive and negative potentials. The conductive filler (conductive particle) is at least one of metal particles and carbon particles. For example, aluminum particles, SUS particles, silver particles, gold particles, copper particles, titanium particles, carbon particles, carbon nanotubes, etc. are used. It is done.

  Polymer materials are polyethylene, polypropylene, polyethylene terephthalate, polyether nitrile, polyimide, polyamide, polytetrafluoroethylene, styrene butadiene rubber, polyacrylonitrile, polymethyl acrylate, polymethyl methacrylate, polyvinyl chloride, polyvinylidene fluoride, Or a mixture of these.

  In addition, as shown in FIG. 1, each positive electrode collector 14 has an end portion extended, and is electrically connected to a positive electrode conductive material 18 for taking out electricity. Each negative electrode current collector 16 is electrically connected to a negative electrode conductive material 19 for taking out electricity, with an end portion extended.

  The positive electrode active material layer 15 formed on the positive electrode 11 includes a positive electrode active material, a conductive additive, a binder, a supporting salt (lithium salt), and the like.

The positive electrode active material contained in the positive electrode active material layer 15 is a positive electrode material capable of accumulating and releasing substances (ions) that travel between the positive electrode 11 and the negative electrode 12 in an electrode reaction. For example, when the battery 5 is a lithium ion secondary battery, a lithium-transition metal composite oxide is preferable. As the positive electrode active material, a Li · Co composite oxide such as LiCoO ₂ or a Li · Co such as LiNiO _{2 is} used. Examples thereof include Ni-based composite oxides, Li · Mn-based composite oxides such as spinel LiMn ₂ O _4, and Li · Fe-based composite oxides such as LiFeO ₂ . In addition, transition metal and lithium phosphate compounds and sulfate compounds such as LiFePO ₄ , transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ , PbO ₂ , AgO, NiOOH etc. are mentioned. In some cases, two or more positive electrode active materials may be used in combination.

  The conductive auxiliary agent contained in the positive electrode active material layer 15 has a function of improving the conductivity of the positive electrode active material. For example, carbon powder such as graphite and various carbon fibers such as vapor grown carbon fiber (VGCF). Consists of.

  The binder contained in the positive electrode active material layer 15 has a function as a binder between the positive electrode current collector 14 and the positive electrode active material layer 15. For example, as a binder, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (PEN), polyimide (PI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), or mixtures thereof.

The supporting salt contained in the positive electrode active material layer 15 has a function as a supporting electrolyte. For example, as the supporting salt, Li (C ₂ F ₅ SO ₂ ) ₂ N (LiBETI), LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li _(C 2 _F 5 _{SO 2),} such as ₂ N and the like.

  The negative electrode active material layer 17 formed on the negative electrode 12 includes a negative electrode active material, a conductive additive, a binder, a supporting salt, and the like.

  The negative electrode active material contained in the negative electrode active material layer 17 is a negative electrode material capable of accumulating and releasing substances (ions) that travel between the positive electrode 11 and the negative electrode 12 in an electrode reaction. For example, a carbon material is preferable as the negative electrode active material. Examples of the carbon material include graphite-based carbon materials (graphite) such as natural graphite, artificial graphite, and expanded graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, and hard carbon. More preferably, graphite such as natural graphite, artificial graphite, and expanded graphite. As natural graphite, for example, scaly graphite, massive graphite and the like can be used. As the artificial graphite, massive graphite, vapor-grown graphite, flaky graphite, and fibrous graphite can be used. Of these, scaly graphite and massive graphite are particularly preferable materials. The use of flaky graphite or massive graphite is particularly advantageous because the packing density increases. In some cases, two or more negative electrode active materials may be used in combination.

  The conductive auxiliary agent contained in the negative electrode active material layer 17 has a function of improving the conductivity of the negative electrode active material. For example, carbon powder such as graphite and various carbon fibers such as vapor grown carbon fiber (VGCF). Consists of.

  The binder contained in the negative electrode active material layer 17 has a function as a binder between the negative electrode current collector 16 and the negative electrode 13, and is made of, for example, polyvinylidene fluoride (PVdF). In addition to a solvent-based binder such as polyvinylidene fluoride, a water-based binder (for example, styrene-butadiene rubber) in which polymer fine particles and a rubber material are dispersed in water may be used.

  The supporting salt contained in the negative electrode active material layer 17 has a function as a supporting electrolyte. For example, the same material as the supporting salt contained in the positive electrode active material layer 15 is used for the supporting salt of the negative electrode 13.

  The separator 13 is provided between the positive electrode 11 and the negative electrode 12 and electrically isolates the positive electrode 11 and the negative electrode 12. The separator 13 holds an electrolytic solution between the positive electrode 11 and the negative electrode 12 to ensure ion conductivity. For example, the separator 13 may be a porous film made of polyolefin such as polypropylene (PP) or polyethylene (PE), or a porous film made of ceramic. Further, aramid having heat resistance may be used.

  As shown in FIG. 1, the positive electrode conductive material 18 is led out of the exterior body 20 while being electrically connected to the power generation element 10 via each positive electrode current collector 14. For example, the positive electrode conductive material 18 is made of aluminum, copper, nickel, iron, titanium, stainless steel, or an alloy thereof. However, it is preferable that the positive electrode conductive material 18 is a metal material that does not melt even when heat is generated when an electric current flows due to an external short circuit in the external discharge unit 30 when a conductive nail is pierced into the assembled battery 1. . Specifically, in the positive electrode conductive material 18, the energy released from when a current flows due to a short circuit until the voltage becomes 0 [V] is (melting point−normal temperature) [K] × heat capacity [cal / K It is preferable that the metal material be less than. And it is good in it being a metal material whose resistance value is lower than the positive electrode collector 14 and the negative electrode collector 16. Here, the “melting point” refers to a temperature at which the positive electrode conductive material 18 melts from a solid to a liquid. “Normal temperature” refers to an annual average temperature (for example, 20 ° C. = − 253 K) in an area where the assembled battery 1 is used. “Heat capacity” refers to the energy required to raise the positive electrode conductive material 18 in contact with the nail by 1 [° C. (K)].

  As shown in FIG. 1, the negative electrode conductive material 19 is led out of the exterior body 20 while being electrically connected to the power generation element 10 via each negative electrode current collector 16. For example, the negative electrode conductive material 19 is made of aluminum, copper, nickel, iron, titanium, stainless steel, or an alloy thereof. Moreover, it is preferable that the negative electrode conductive material 19 is a metal material that does not melt even when heat is generated when a current is caused by a short circuit when a conductive nail is inserted into the assembled battery 1. Specifically, in the negative electrode conductive material 19, the energy released from when a current flows due to a short circuit until the voltage becomes 0 [V] is (melting point−normal temperature) [K] × heat capacity [cal / K It is preferable that the metal material be less than. In addition, a metal material having a lower resistance than the positive electrode current collector 14 and the negative electrode current collector 16 is more preferable.

The electrolytic solution is a non-aqueous (system) electrolytic solution, and the ions stored between the positive electrode 11 and the negative electrode 12 are charged / discharged by the ions moving between the positive electrode 11 and the negative electrode 12 through the electrolytic solution. For example, the electrolytic solution is in a form in which a lithium salt or the like as a supporting salt is dissolved in an organic solvent. The organic solvent is not particularly limited as long as it can sufficiently dissolve the supporting salt. For example, (1) cyclic carbonates such as propylene carbonate and ethylene carbonate, (2) chains such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate. (3) ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, (4) lactones such as γ-butyrolactone, (5) Nitriles such as acetonitrile, (6) Esters such as methyl propionate, (7) Amides such as dimethylformamide, (8) One or two kinds selected from methyl acetate and methyl formate Plasticizers such as aprotic solvents mixed with the above It is. These organic solvents may be used alone or in combination of two or more. Conventionally known salts are used as the supporting salt. For example, Li (C ₂ F ₅ SO ₂ ) ₂ N (LiBETI), LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N or the like is used.

  The exterior body 20 is composed of, for example, a laminate sheet having a metal plate therein, and covers and seals the power generation element 10 from both sides. Thereby, the exterior body 20 accommodates the power generation element 10.

  As shown in the broken line in FIG. 1, the external discharge unit 30 includes a positive electrode conductive material 18 and a negative electrode conductive material 19 that are electrically connected to other electronic devices for charging and discharging, and an insulating member 31 having an insulating property. Are stacked. That is, the positive electrode conductive material 18 that functions as the positive electrode tab of the assembled battery 1 and the negative electrode conductive material 19 that functions as the negative electrode tab are external to the exterior body 20 of at least one of the batteries 5. In the discharge part 30, the power generation element 10 is laminated via the exterior body 20. In FIG. 1, among the plurality of batteries 5 stacked in a row, the positive electrode conductive material 18 derived from the uppermost battery 5 and the negative electrode conductive material 19 derived from the lowermost battery 5 are the uppermost layer. The example laminated | stacked on the electric power generation element 10 via the exterior body 20 of the battery 5 of this is shown. In the external discharge part 30, an insulating member 31 is disposed between the positive electrode conductive material 18 and the negative electrode conductive material 19. Further, since the assembled battery 1 has a structure in which a plurality of batteries 5 are connected in series, the negative electrode conductive material 19 derived from the uppermost battery 5 is replaced with the positive electrode conductive material 18 derived from the intermediate layer battery 5. And electrically connected. Similarly, the negative electrode conductive material 19 derived from the intermediate layer battery 5 is electrically connected to the positive electrode conductive material 18 derived from the lowermost layer battery 5.

  As shown in FIG. 1, in the external discharge part 30, the positive electrode conductive material 18 has a folded structure. By having such a folded structure, fusing due to electric discharge is suppressed. On the other hand, the negative electrode conductive material 19 does not have a folded structure. Therefore, the tip of the positive electrode conductive material 18 and the tip of the negative electrode conductive material 19 are aligned in the same direction.

  The insulating member 31 prevents contact between the positive electrode conductive material 18 and the negative electrode conductive material 19 in the external discharge part 30 and electrically separates them. As a material constituting such an insulating member 31, it has insulating properties, sealing properties against sealing off of solid electrolyte (sealing properties), sealing properties against moisture permeation from the outside, heat resistance under battery operating temperature, and the like. Anything is acceptable. For example, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyimide resin, rubber and the like are used. In particular, it is preferable to use a urethane resin or an epoxy resin from the viewpoints of corrosion resistance, chemical resistance, ease of production (film forming property), economy, and the like.

  Since the assembled battery 1 of the present embodiment has the above-described structure, when the conductive nail is stabbed, the positive electrode conductive material 18 and the negative electrode conductive material 19 are short-circuited through the nail in the external discharge unit 30. . Due to this external short circuit, a large current flows through the external discharge unit 30, but is instantaneously discharged to the outside of the assembled battery 1 through the nail. Therefore, the current is less likely to concentrate on the nail portion in the power generation element 10, and local Joule heat based on an internal short circuit does not occur. In addition, since heat generated by the spark outside the exterior body 20 is insulated by the exterior body 20, it is difficult to be transmitted to the power generation element 10. Thus, the battery 1 does not lose its battery function due to nail penetration, and safety is ensured.

  As described above, the assembled battery 1 according to the present embodiment can generate Joule heat from the power generation element 10 of each battery 5 even when a nail is stabbed. Heat is not transmitted. Therefore, the assembled battery 1 of this embodiment does not lose the battery function due to nail penetration, and safety is ensured.

  In addition, the positive electrode current collector 14 of the present embodiment includes a polymer material. Therefore, the weight can be reduced as compared with a metal current collector made of only a metal material, and the power density per weight can be increased as compared with a conventional metal current collector.

  In addition, for the positive electrode conductive material 18 and the negative electrode conductive material 19 of the present embodiment, a metal material having a lower resistance value than the positive electrode current collector 14 and the negative electrode current collector 16 may be used. By employing the positive electrode conductive material 18 and the negative electrode conductive material 19 having such properties, when the nail is inserted into the assembled battery 1, the positive electrode outside the battery 5, not the power generation element 10 in each battery 5. Current flows through the conductive material 18 and the negative electrode conductive material 17, facilitating discharge to the outside of the assembled battery 1.

<Modification>
The above embodiments are intended to exemplify the gist of the present invention and do not limit the present invention. Many alternatives, modifications, and variations will be apparent to those skilled in the art. Examples of modifications include the following.

  For example, in the above embodiment, only the positive electrode conductive material 18 has a folded structure in the external discharge part 30. However, the present invention is not limited to this, and it is sufficient that at least one of the positive electrode conductive material 18 and the negative electrode conductive material 19 has a folded structure in the external discharge portion 30.

  FIG. 2 is a diagram illustrating a first modification of the external discharge unit. FIG. 3 is a diagram illustrating a second modification of the external discharge unit. FIG. 4 is a diagram illustrating a third modification of the external discharge unit.

  As shown in FIG. 2, only the negative electrode conductive material 19 may have a folded structure. Also by this, the front end of the positive electrode conductive material 18 and the front end of the negative electrode conductive material 19 can be aligned in the same direction.

  Moreover, as shown in FIG. 3, both the positive electrode conductive material 18 and the negative electrode conductive material 19 may have a folded structure. Thereby, the thickness of the external discharge part 30 increases, and it is possible to earn time from the start of nail penetration until the nail reaches the power generation element 10 of each battery 5. Therefore, the external discharge unit 30 can reliably discharge the nail before reaching the power generation element 10 of each battery 5.

  In addition, as shown in FIG. 4, the number of times of folding may be different between the positive electrode conductive material 18 and the negative electrode conductive material 19. For example, as shown in FIG. 4, the positive electrode conductive material 18 may be folded once and the negative electrode conductive material 19 may be folded twice. In this way, even if the number of times of folding is large, the tip of the positive electrode conductive material 18 and the tip of the negative electrode conductive material 19 can be aligned in the same direction.

  In addition, the frequency | count of folding the positive electrode electrically-conductive material 18 and the negative electrode electrically-conductive material 19 in the external discharge part 30 is not limited to the example shown in FIGS. 1-4, and how many times may be folded.

  Moreover, in the said embodiment and modification, all the batteries 5 contained in the assembled battery 1 are laminated | stacked on 1 row. Thereby, the installation area (width x depth) of the assembled battery 1 can be minimized. However, the present invention is not limited to this. For example, some of the batteries 5 may be arranged side by side without being stacked. Even in such a case, the external discharge unit 30 may be disposed on the top of at least one of the batteries 5 and stacked on a part of the power generation elements 10 via the exterior body 20 of the battery 5. .

  FIG. 5 is a diagram illustrating a fourth modification of the external discharge unit. FIG. 6 is a diagram illustrating a fifth modification of the external discharge unit.

  As shown in FIG. 5, all the batteries 5 included in the assembled battery 1 may be arranged side by side without being stacked. In the illustrated example, the external discharge unit 30 is disposed so as to cover all the batteries 5 from above, and is stacked on each power generation element 10 via the exterior body 20 of each battery 5. In FIG. 5, all the batteries 5 are connected in series. Even with the assembled battery 1 having such a structure, when the nail is pierced, the external discharge unit 30 discharges the heat, and the heat generated at this time is not transmitted to the power generation element 10 of each battery 5.

  Further, as shown in FIG. 6, a part of the batteries 5 included in the assembled battery 1 may be stacked, and the remaining batteries 5 may be stacked on the side. In the illustrated example, the external discharge unit 30 is arranged so as to cover the batteries 5 stacked on the left and right separately from each other from the top, and to each power generation element 10 via the outer body 20 of the upper two batteries 5. Laminated. In FIG. 6, the upper and lower batteries 5 are connected in series, and the upper and lower batteries are connected in parallel. Even with the assembled battery 1 having such a structure, when the nail is pierced, the external discharge unit 30 discharges the heat, and the heat generated at this time is not transmitted to the power generation element 10 of each battery 5.

  Moreover, in the said embodiment, although the example of the electroconductive filler contained in the current collection foil of the positive electrode collector 14 and the negative electrode collector 16 was given, it is not limited to the said example. For example, alloy particles may be used as the conductive filler. Moreover, the material put into practical use as what is called a filler type conductive resin composition can be used. In particular, carbon particles that are often used as conductive aids in batteries are preferred. This is because carbon particles such as carbon black and graphite have a very wide potential window, and are therefore stable in a wide potential range with respect to both the positive electrode potential and the negative electrode potential, and also have excellent conductivity. It is. Moreover, since the carbon particles are very light, the mass of the entire battery can be minimized.

  Further, in the above embodiment, the positive electrode conductive material 18 and the negative electrode conductive material 19 are formed of a single member from the tip inside the outer package 20 of each battery 5 to the tip of the external discharge part 30. However, the present invention is not limited to this, and may be formed by a plurality of members. For example, a member conventionally used as a current collecting tab is used for the seal portion of the outer package 20 of each battery 5, and the members of the above embodiment are provided from the seal portion of the outer package 20 to the tip of the external discharge unit 30. May be used. For example, aluminum, copper, nickel, iron, titanium, stainless steel, and alloys thereof are used as the current collecting tab. The positive electrode conductive material 18 and the negative electrode conductive material 19 that electrically connect the plurality of batteries 5 may be formed of a single member or different members.

  Moreover, in the said embodiment, the assembled battery 1 demonstrated as what is comprised from the some battery 5. FIG. However, the assembled battery 1 may be a battery module in which a plurality of batteries 5 are housed in a case (can), or may be a combination of a plurality of battery modules.

  Moreover, in the said embodiment, although the lithium ion secondary battery is mentioned as an example of the battery 5, if it is a battery used for the assembled battery 1 which has the external discharge part 30, it will not depend on the name and structure.

  Moreover, although the laminated battery is employ | adopted as the battery 5 of the said embodiment, it is not limited to this, You may replace at least 1 laminated battery among several laminated batteries with a bipolar battery. Thereby, the capacity | capacitance and voltage in the assembled battery 1 whole can be adjusted freely. Moreover, you may adjust a capacity | capacitance and a voltage freely by connecting a part of several battery 5 connected in series electrically in parallel. For example, like the assembled battery 1 shown in FIG. 6, two batteries 5 connected in series may be connected in parallel.

  Although not particularly described in the above embodiment, the power generation element 10 of each battery 5 is sealed in the exterior body 20 under reduced pressure in order to prevent external impact during use and environmental degradation.

  Moreover, although the said embodiment demonstrated that the insulating member 31 functions as a heat insulating material, it is not limited to this, When the external short circuit arises by nail penetration, the heat | fever generate | occur | produced in the external discharge part 30 is each battery. If it is a thing of the form which is not transmitted to the inside of the exterior body 20 of 5, it will not depend on the name or structure. For example, the heat generated in the external discharge unit 30 by nail penetration may be released to the vehicle body via a conductive material arranged around each battery 5 or may be cooled using cooling water or the like.

  Moreover, the assembled battery 1 of the said embodiment can be mounted in a vehicle. The assembled battery 1 mounted on the vehicle is used as a power source for driving a motor of the vehicle, for example. In addition, when the assembled battery 1 is mounted in a vehicle, it is preferable that the external discharge unit 30 is disposed so as to face the traveling direction of the vehicle.

<Example 1>
As Example 1, an assembled battery 1 having the structure described in the above embodiment was produced. Specifically, an aluminum plate having a thickness of 0.2 [mm] was used as the positive electrode conductive material 18 and the negative electrode conductive material 19. And in the external discharge part 30, the frequency | count of folding of the positive electrode electrically-conductive material 18 was made into 1 time, and the frequency | count of folding of the negative electrode electrically-conductive material 19 was made into 2 times (a total of 3 times). When a nail penetration test was performed on the assembled battery 1 produced in this manner, the battery function was not lost and good results were obtained.

<Comparative Example 1>
Further, as Comparative Example 1, an assembled battery 1 having the structure described in the above embodiment was produced. Specifically, aluminum plates having a thickness of 0.2 [mm] were used as the positive electrode conductive material 18 and the negative electrode conductive material 19. And in the external discharge part 30, the positive electrode conductive material 18 and the negative electrode conductive material 19 were made into the linear plate-shaped structure without folding. When the nail penetration test was performed on the assembled battery 1 thus manufactured, the battery function was lost.

  From the above, if the thickness of the external discharge part 30 is increased, the time from the start of nail penetration until the nail reaches the power generating element 10 of each battery 5 can be gained, and the battery function is lost. I found it difficult.

1 battery pack,
5 batteries,
10 power generation elements,
11 positive electrode,
12 negative electrode,
13 separator,
14 positive electrode current collector,
15 positive electrode active material layer,
16 negative electrode current collector,
17 negative electrode active material layer,
18 positive electrode conductive material,
19 negative electrode conductive material,
20 exterior body,
30 External discharge part,
31 Insulating member.

Claims (7)

An assembled battery in which at least some of the stacked batteries are connected in series,
The stacked battery is:
A power generation element in which a positive electrode having a positive electrode active material layer formed on both sides of a current collector and a negative electrode having a negative electrode active material layer formed on both sides of the current collector are alternately stacked via separators;
An exterior body that houses the power generation element;
A positive electrode conductive material led out of the exterior body while being electrically connected to the power generation element via the positive electrode current collector;
A negative electrode conductive material that is electrically connected to the power generation element via the negative electrode current collector and led out of the exterior body,
The positive electrode conductive material and the negative electrode conductive material that are electrically connected to other electronic devices for charging / discharging are led out of an exterior body of at least one of the plurality of stacked batteries. A part is laminated to the power generation element via the outer body to form an external discharge part,
An assembled battery in which an insulating member having an insulating property is disposed between the positive electrode conductive material and the negative electrode conductive material in the external discharge portion.   2. The assembled battery according to claim 1, wherein at least one of the positive electrode conductive material and the negative electrode conductive material has a folded structure in the external discharge portion.   The assembled battery according to claim 1 or 2, wherein the plurality of stacked batteries are stacked in a line.   The assembled battery according to any one of claims 1 to 3, wherein at least one of the plurality of stacked batteries is replaced with a bipolar battery.   When an internal short circuit occurs in the power generation element, the positive electrode conductive material and the negative electrode conductive material are short-circuited outside the exterior body of each stacked battery, and the positive electrode conductive material and the negative electrode conductive material The assembled battery according to any one of claims 1 to 4, wherein energy released until the voltage reaches 0 [V] is less than "(melting point-normal temperature) x heat capacity".   The assembled battery according to any one of claims 1 to 5, wherein the positive electrode conductive material and the negative electrode conductive material have a smaller electric resistance than a current collector included in the electrode.   The assembled battery according to claim 1, wherein the current collector includes a polymer material and conductive particles.