JP2004071217A - Battery assembly composed of two or more laminated batteries, and vehicle mounting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new folding method of a sealing part of laminated batteries, and to heighten the usefulness of a plurality of laminated batteries. <P>SOLUTION: For the battery assembly formed by combining a plurality of laminated batteries which is formed by sealing battery elements in a laminated sheet, a sealed part of one laminated battery and the sealed part of another batteries adjacent to the one battery are wound with overlap. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an assembled battery including a plurality of laminated batteries, and more particularly, to an assembled battery characterized by a method of folding a sealing portion of the laminated battery.
[0002]
[Prior art]
2. Description of the Related Art In recent years, the development of a motor driving battery has been earnestly pursued for practical use of an electric vehicle (EV), a hybrid vehicle (HEV), and a fuel cell vehicle (FCV). As a motor driving battery, use of a rechargeable secondary battery has been proposed.
[0003]
The forms of the secondary batteries proposed so far include a can battery having a structure in which a battery element is disposed inside a metal can, and a laminate having a structure in which the battery element is sealed using a laminate sheet. There are batteries. As a power source for a mobile body such as an automobile, a laminated battery that is useful for reducing the weight and size is preferable.
[0004]
The battery element of the laminated battery is sealed inside the laminate sheet by heat-sealing the laminate sheet. Therefore, a seal portion is formed around the laminate battery where the two laminate sheets are thermally fused. However, this sealed portion causes dead space when a plurality of laminated batteries are combined to produce an assembled battery. Therefore, in order to improve the volume energy density of the battery pack, it is preferable to reduce the width of the sealing portion.
[0005]
On the other hand, if the width of the sealing portion is too small, moisture in the outside air permeates into the inside of the laminated battery, which causes deterioration of battery characteristics. If the width of the seal portion is too small, the seal portion may be peeled off due to insufficient adhesive strength.
[0006]
That is, from the viewpoint of battery characteristics, the smaller the sealing portion is, the more preferable. On the contrary, from the viewpoint of battery reliability, the larger the sealing portion is, the more preferable.
[0007]
As a technique for solving this problem, there is a laminated battery described in Japanese Patent Application Laid-Open No. 2000-200555. The publication discloses a technique for reducing the area occupied by the sealing portion by bending the sealing portion of the laminated battery. That is, the reliability and the volume energy density of the battery are improved by bending the sealing portion having a sufficient width.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a new method for bending a sealed portion of a laminated battery, and to enhance the usefulness of an assembled battery including a plurality of laminated batteries.
[0009]
[Means for Solving the Problems]
The present invention is an assembled battery in which a plurality of laminated batteries in which battery elements are sealed inside a laminate sheet are combined, and a sealed portion of one laminated battery and a laminated battery adjacent to the one laminated battery are provided. The battery pack is characterized in that the seal portion is wound in an overlapping manner.
[0010]
【The invention's effect】
In the assembled battery of the present invention, the seal portions of the plurality of laminated batteries are wound up in an overlapping manner. Therefore, the dead space in the battery pack is small, and the volume energy density of the battery pack is high. Further, the compact assembled battery of the present invention is excellent in mountability as various power sources.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The first aspect of the present invention is an assembled battery in which a plurality of laminated batteries in which battery elements are sealed inside a laminate sheet are combined, and a sealed portion of one laminated battery and an adjacent to the one laminated battery are provided. A sealed battery in which a sealing portion of a laminated battery is overlapped and wound. The present invention will be described below with reference to the drawings.
[0012]
FIG. 1 is a side view of an embodiment of the battery pack 101 of the present invention. In FIG. 1, for convenience of explanation, the assembled battery 101 is composed of two laminated batteries 103, but the number of laminated batteries constituting the assembled battery is not particularly limited. Rather, the effect of the present invention in which the dead space is reduced increases as the number of laminated batteries constituting the assembled battery increases. The number of laminated batteries 103 to be combined may be determined according to the output of the batteries and the like.
[0013]
The laminated battery 103 has a structure in which a battery element (not shown) including a positive electrode, a negative electrode, a separator, and the like, in which a charge / discharge reaction actually proceeds, is sealed inside the laminate sheet 105. Battery element components such as a positive electrode, a negative electrode, a separator, and an electrolyte are usually laminated. The number of stacked battery element components is determined according to the battery characteristics required for the laminated battery. The size of the laminated battery is also determined according to the battery characteristics and installation environment required for the laminated battery. Generally, the battery element is sealed inside the laminate sheet 105 using heat fusion. At this time, in order to ensure the sealing performance of the laminated battery 103, a sealing portion having a certain width is required. In the laminated battery of the present invention, the sealing portions 107 of the adjacent laminated batteries are overlapped and wound. By such a process, the dead space generated by the sealing portion of the laminated battery can be reduced, and the size of the assembled battery can be reduced and the volume energy density can be improved. In particular, in the assembled battery of the present invention, since the sealing portion 107 of the laminated battery is wrapped around, it can greatly contribute to miniaturization of the assembled battery and improvement of the volume energy density. Note that the seal portion refers to a portion to which a laminate sheet is adhered in order to seal a battery element, and generally refers to a portion which is heat-sealed.
[0014]
FIG. 1 shows an embodiment in which only the seal portion 107 located between two adjacent laminated batteries is wound, but the present invention is not limited to such an embodiment. When three or more laminated batteries are arranged side by side, it is preferable to completely wind the sealing portion between the laminated batteries in order to reduce the size of the assembled battery and improve the volume energy density. is there. In addition, the sealing portion 107 ′ located at the end and in a portion where the adjacent laminated battery does not exist may be folded or wound in order to reduce the size of the battery pack and improve the volume energy density. Is preferred.
[0015]
Although the battery pack 101 of FIG. 1 is wound around the sealing portion 107 of the laminated battery 103 arranged adjacent to the plane direction, it may be wound around the sealing portion of the laminated battery stacked vertically. Good (not shown). Such an embodiment is also included in the concept of “the seal portion of the laminated battery adjacent to one laminated battery is overlapped and wound” in the present application. In some cases, the sealing portions of three or more vertically laminated laminated batteries may be overlapped and wound.
[0016]
Batteries that are small and have excellent volumetric energy density are particularly meaningful when battery mounting space is limited. For example, in an application, such as a vehicle, in which a demand for miniaturization of a battery mounting space is particularly strong, the effect of the assembled battery of the present invention is large.
[0017]
The lap winding shape of the sealing portion of the laminated battery is not particularly limited. As shown in FIG. 1, the shape when observed from the side of the laminated battery is preferably a circle, an ellipse, a square, or a triangle. Preferably, the shape when observed from the side of the laminated battery is circular or elliptical. When winding is performed such that there is no angular portion such as a circle or an ellipse, the force applied to the seal portion is dispersed, and damage to the seal portion is prevented.
[0018]
Preferably, the sealing portion of the laminated sheet 105 of one laminated battery and the sealing portion of the laminated sheet 105 'of the laminated battery adjacent to the one laminated battery are circles having a hollow portion as shown in FIG. It is preferable to be wound in a column shape. In the present application, “the columnar shape having a hollow portion” means a state in which the sealing portion of the laminated battery is wound so that a space is created in the central portion. Further, in the present application, the term “cylindrical shape” is a concept including not only a perfect cylinder but also a shape in which the cylinder is shy.
[0019]
When the seal portion 107 to be overlapped and wound has a columnar shape, as described above, the force applied to the seal portion is dispersed, and damage to the seal portion is prevented. In addition, when the wiring cord is inserted into the hollow portion, the space where the seal portion 107 is disposed can be effectively used. Such an embodiment will be described with reference to FIGS.
[0020]
FIG. 2 is a plan view of the assembled battery 201 in which the sealing portion 207 existing between the two laminated batteries 203 and 203 'is overlapped and wound up to form two layers. FIG. 3 is a side view of the battery pack of FIG. 2 as seen from the direction III. Tabs 209 for use in electrical connection are drawn out from the laminated battery 203, and are connected via the tabs 209. When a battery pack is mounted, the voltage may be measured in order to manage the charge / discharge state of each battery.However, when the seal portion is wound in a cylindrical shape having a hollow portion, the hollow portion is Battery voltage measurement wiring 211 for measuring the voltage state of the laminated battery can be inserted. The space occupied by the seal portion 207 can be effectively used by inserting the seal portion 207 that is overlapped and wound so as to have a hollow portion. In addition, since it can be used as a wiring path for the battery voltage measurement wiring 211, the degree of freedom in designing wiring is increased. Further, the wiring can be simplified, and the work for wiring to the assembled battery is facilitated. Such a feature is effective in a case where wiring is arranged in a complicated manner, such as an assembled battery including a large number of laminated batteries.
[0021]
Although the case where the wiring penetrating the hollow part existing in the seal part 207 is the battery voltage measurement wiring has been described, the wiring penetrating the hollow part is not limited to the battery voltage measurement wiring. Wiring other than the battery voltage measurement wiring may be inserted. Even in such a case, by inserting the wiring through the hollow portion, the effect of shortening the wiring length and reducing the space occupied by the wiring can be obtained. . Other wiring is not particularly limited, and is determined according to the use of the battery pack of the present invention. For example, when the battery pack of the present invention is mounted on an automobile, wiring that penetrates the hollow portion is selected from the control system wiring and the wiring connected to the sensor around the space where the battery pack is arranged. You.
[0022]
The size of the hollow portion may be determined according to the wiring passing through the hollow portion. Considering that the diameter of commonly used wiring is 1 to 3 mm, the short axis diameter of the hollow portion is preferably 2 mm or more, more preferably 3 mm or more, and particularly preferably 4 mm or more. preferable. On the other hand, if the hollow portion is too large, the volume occupied by the sealing portion of the laminated battery will increase, and the volume energy density of the assembled battery will decrease. For this reason, the short axis system of the hollow portion is preferably 20 mm or less, more preferably 15 mm or less, and particularly preferably 10 mm or less.
[0023]
When two or more assembled batteries of the present invention are combined, it is preferable that the assembled batteries are stacked so that a portion where the seal portion of the laminated battery is overlapped and wound (hereinafter, also referred to as “overlapping portion”) overlaps. That is, it is preferable that the one assembled battery and the other assembled battery are stacked so that the overlapped wound portion of one assembled battery and the overlapped wound portion of the other assembled battery overlap. FIG. 3 is a side view of an embodiment in which an assembled battery including two laminated batteries is stacked in two layers. With such an arrangement, the dead space can be reduced more efficiently. Further, the length of wiring required for electrically connecting the laminated batteries can be easily reduced.
[0024]
As described above, the sealing portions of three or more laminated batteries may be wound in a loop. In a case where four laminated batteries are combined as shown in FIG. 3, when four seal portions are overlapped and wound, the two overlapping wound portions in FIG. 3 can be made one (not shown). However, it should be noted that the volume occupied by the lap-wrapped portion increases as the number of seal portions lap-wrapped increases.
[0025]
Examples of the laminated battery of the present invention include a lithium ion secondary battery, a polymer lithium battery, a nickel-hydrogen battery, and a nickel-cadmium battery. Among these, a lithium ion secondary battery excellent in output and energy density is preferable in consideration of the use as a vehicle power supply. When a battery pack in which laminated batteries, which are lithium ion secondary batteries, are connected in series is used as a vehicle power supply, a battery pack having an overall output voltage of about 400 V can be obtained.
[0026]
In the laminated battery of the present invention, a material such as a battery element, a tab, and a laminate sheet may be a known material, and is not particularly limited. For reference, the case where the laminated battery of the present invention is a lithium ion secondary battery will be briefly described below. However, the laminated battery of the present invention is not limited to a lithium ion secondary battery.
[0027]
[Positive electrode]
The positive electrode has a structure in which a positive electrode material is bonded to both surfaces of a positive electrode current collector made of aluminum or the like. Examples of the cathode material include various oxides (lithium manganese oxide such as LiMn ₂ O ₄ ; manganese dioxide; lithium nickel oxide such as LiNiO ₂ ; lithium cobalt oxide such as LiCoO ₂ ; lithium-containing nickel cobalt oxide; And chalcogen compounds (such as titanium disulfide and molybdenum disulfide). Among these, lithium manganese oxide or lithium nickel oxide is preferable in consideration of the output characteristics of the obtained lithium ion secondary battery.
[0028]
A conductive material may be bound to the positive electrode current collector in order to improve conductivity. Examples of the conductive material include artificial graphite, carbon black (eg, acetylene black), nickel powder, and the like.
[0029]
As the positive electrode current collector, for example, expanded metal made of aluminum, aluminum mesh, punched metal made of aluminum, or the like can be used. Note that the positive electrode may have a structure in which a positive electrode material is bound to one surface of a positive electrode current collector.
[0030]
[Negative electrode]
The negative electrode has a structure in which a negative electrode material is bonded to both surfaces of a negative electrode current collector made of copper or the like. As the negative electrode material, a carbon material that stores and releases lithium ions can be used. As such a carbon material, natural graphite, artificial graphite, carbon black, activated carbon, carbon fiber, coke, and an organic precursor (for example, phenol resin, polyacrylonitrile, cellulose, etc.) were synthesized by heat treatment in an inert atmosphere. Carbon and the like. Preferably, the negative electrode is made of an amorphous carbon-based material. In the present application, "amorphous carbon-based material" means a carbon material having no crystal structure, in other words, an amorphous carbon material. Such an amorphous carbon-based material is obtained by carbonizing a thermosetting resin. Incidentally, when an amorphous carbon-based material having a large voltage dependency due to discharge is used, the cycle characteristics of the lithium ion secondary battery when two or more lithium ion secondary batteries are connected in parallel can be improved.
[0031]
As the negative electrode current collector, for example, a copper expanded metal, a copper mesh, a copper punched metal, or the like can be used. Note that the negative electrode may have a structure in which a negative electrode material is bound to one surface of a negative electrode current collector.
[0032]
[Separator]
As the separator, a polyolefin-based microporous separator, for example, polyethylene or polypropylene can be used, and the separator is impregnated with a non-aqueous electrolyte. The non-aqueous electrolyte is prepared by dissolving the electrolyte in a non-aqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and γ-butyrolactone (γ-BL). ), Sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. The non-aqueous solvents may be used alone or as a mixture of two or more. Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium boron tetrafluoride (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), and lithium trifluoromethanesulfonate. (LiCF ₃ SO ₃ ) and lithium salts of lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₃ ) ₂ ]. The amount of the electrolyte dissolved in the nonaqueous solvent is usually about 0.2 mol / L to 2 mol / L.
[0033]
Examples of the polymer that holds the non-aqueous electrolyte include a polyethylene oxide derivative, a polypropylene oxide derivative, a polymer containing the derivative, a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), and the like.
[0034]
[Laminate sheet]
The laminate sheet is used as a battery exterior material. Generally, a polymer-metal composite film in which a heat-fusible resin film, a metal foil, and a rigid resin film are laminated in this order is used.
[0035]
As the heat-fusible resin, for example, polyethylene (PE), ionomer, ethylene vinyl acetate (EVA) and the like can be used. As the metal foil, for example, an Al foil or a Ni foil can be used. As the resin having rigidity, for example, polyethylene terephthalate (PET), nylon or the like can be used. Specifically, a laminated film of PE / Al foil / PET laminated from the sealing surface side to the outer surface; a laminated film of PE / Al foil / nylon; a laminated film of ionomer / Ni foil / PET; EVA / Al foil / A laminated film of PET; a laminated film of ionomer / Al foil / PET can be used. The heat-fusible resin film functions as a seal layer when the battery element is housed inside. A metal foil or a rigid resin film imparts moisture, air resistance, and chemical resistance to the exterior material. The laminate sheets can be easily and reliably joined by using ultrasonic fusion or the like.
[0036]
[tab]
A metal selected from copper and iron can be used for the tab, but a metal such as aluminum or stainless steel or an alloy material containing these can also be used. Nickel is most preferably used for the surface coating layer, but metal materials such as silver and gold can also be used.
[0037]
Subsequently, a method for manufacturing the battery pack of the present invention will be briefly described.
[0038]
First, a laminated battery is prepared. The shape and type of the laminated battery are not particularly limited. For example, when a laminated battery that is a lithium ion secondary battery is used, the laminated battery may be composed of the above-described materials.
[0039]
Next, the sealing portions of the laminated batteries that are arranged adjacent to each other are overlapped and wound. One method of lap winding will be described with reference to FIG. First, the laminated batteries to be overlapped and wound are overlapped. When overlapping, when the surfaces on which the seal portion 307a is overhanging are overlapped, the overlap winding of the seal portion 307a is easy, and the work convenience is high.
[0040]
The lap winding method is not particularly limited. In the case of lap winding in a cylindrical shape having a hollow portion, the sealing portion is wound using a thin iron rod having a desired diameter, and after being wound, the iron bar is removed to have a hollow portion of a predetermined size. A wound seal portion 307b can be formed. It may be processed by passing a sealing portion through a curling mold having a predetermined curvature. Further, if necessary, the seal portion located on the opposite side of the overlap-wrapped seal portion is likewise overlap-wound.
[0041]
The assembled battery in which the seal portion is overlapped is electrically connected to form an assembled battery. The effect when the wiring is inserted into the hollow portion is as described above. In some cases, it may be possible to use a wire inserted into the hollow portion to perform overlapping winding.
[0042]
The second aspect of the present invention is a vehicle equipped with the battery pack. For reference, FIG. 5 shows a perspective view of a vehicle (automobile) 413 on which the battery pack of the present invention is mounted. The assembled battery 401 mounted on the vehicle has a high volume energy density. For this reason, the occupied volume of the battery portion in the vehicle can be reduced, and the degree of design freedom is high. It is also useful for securing space for people and luggage in vehicles.
[Brief description of the drawings]
FIG. 1 is a side view of an embodiment of an assembled battery according to the present invention.
FIG. 2 is a plan view of an assembled battery including two laminated batteries connected in series.
FIG. 3 is a side view of the battery pack of FIG. 2 as viewed from a direction III.
FIG. 4 is a diagram showing one embodiment of a method of overlapping winding a seal portion.
FIG. 5 is a perspective view of a vehicle on which the battery pack of the present invention is mounted.
[Explanation of symbols]
101, 201, 401 ... assembled battery, 103, 203, 203 '... laminated battery, 105, 105' ... laminated sheet, 107, 107 ', 207, 307a, 307b ... sealed part, 209 ... tab, 211 ... battery voltage measurement Wiring, 413: automobile as a vehicle

Claims (5)

A battery assembly in which a plurality of laminated batteries in which battery elements are sealed inside the laminate sheet are combined,
An assembled battery comprising: a sealed portion of one laminated battery; and a sealed portion of a laminated battery adjacent to the one laminated battery, which are overlapped and wound. 2. The set according to claim 1, wherein the sealing portion of the one laminated battery and the sealing portion of the laminated battery adjacent to the one laminated battery are rolled up in a cylindrical shape having a hollow portion. 3. battery. 3. The battery pack according to claim 1, wherein a wiring cord is inserted through the hollow portion. The battery pack according to any one of claims 1 to 3, wherein the wiring cord is a battery voltage measurement wiring. A vehicle equipped with the battery pack according to claim 1.

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