JP4039164B2 - A battery pack comprising a plurality of laminate batteries and a vehicle equipped with the battery pack - Google Patents

Description

[0001]
BACKGROUND 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 bending a seal portion of a laminated battery.
[0002]
[Prior art]
2. Description of the Related Art In recent years, motor drive batteries have been developed with the aim of putting electric vehicles (EV), hybrid vehicles (HEV), and fuel cell vehicles (FCV) into practical use. As a battery for driving a motor, the use of a secondary battery that can be repeatedly charged has been proposed.
[0003]
Examples of the secondary battery proposed so far include a can battery having a structure in which battery elements are arranged inside a metal can, and a laminate having a structure in which battery elements are 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 weight and size is preferable.
[0004]
The battery element of the laminate battery is sealed inside the laminate sheet by heat-sealing the laminate sheet. Therefore, a seal portion in which two laminate sheets are heat-sealed is generated around the laminate battery. However, this seal portion causes dead space when a battery pack is manufactured by combining a plurality of laminate batteries. Therefore, in order to improve the volume energy density of the assembled battery, it is preferable to reduce the width of the seal portion.
[0005]
On the other hand, when the width of the seal portion is too small, moisture in the outside air permeates into the laminated battery, causing deterioration of battery characteristics. Further, if the width of the seal portion is too small, the seal portion may be peeled off due to insufficient adhesive force.
[0006]
That is, the smaller the seal portion is, the better from the viewpoint of battery characteristics, but conversely, the larger the seal portion is, from the viewpoint of battery reliability.
[0007]
As a technique for solving this problem, there is a laminated battery described in JP-A-2000-200585. This publication discloses a technique for reducing the area occupied by the seal portion by bending the seal portion of the laminated battery. That is, the reliability and volume energy density of the battery are improved by bending a seal 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 folding a sealing 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 laminated sheet are combined, and includes a sealing portion of one laminated battery and a laminated battery adjacent to the one laminated battery. 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 a plurality of laminated batteries are wound up in an overlapping manner. For this reason, the dead space in an assembled battery is small and the volume energy density of an assembled battery is high. The compact assembled battery of the present invention is excellent in mountability as various power sources.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
A first aspect of the present invention is an assembled battery formed by combining a plurality of laminated batteries in which battery elements are sealed inside a laminated sheet, and is adjacent to the sealed portion of one laminated battery and the one laminated battery. The battery pack is characterized in that the laminated battery is wound in an overlapping manner. The present invention will be described below with reference to the drawings.
[0012]
FIG. 1 is a side view of an embodiment of an assembled battery 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 dead space is reduced is greater as the number of laminated batteries constituting the assembled battery is larger. The number of laminated batteries 103 to be combined may be determined according to the output of the battery.
[0013]
The laminate battery 103 has a structure in which a battery element (not shown) that is actually made up of a positive electrode, a negative electrode, a separator, and the like and that undergoes a charge / discharge reaction 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. In general, 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 laminate battery 103, a seal portion having a certain width is required. In the laminate battery of the present invention, the seal portion 107 of the adjacent laminate battery is wound in layers. Such a process can reduce the dead space caused by the sealing portion of the laminated battery, and can reduce the size of the assembled battery and improve the volume energy density. In particular, in the battery pack of the present invention, since the sealing portion 107 of the laminated battery is lap-wrapped, it can greatly contribute to downsizing the battery pack and improving the volume energy density. In addition, a sealing part means the part to which the laminate sheet is adhere | attached in order to seal a battery element, and usually means the part heat-sealed.
[0014]
Although FIG. 1 shows an embodiment in which only the seal portion 107 positioned between two adjacent laminated batteries is wound, the present invention is not limited to such a form. When three or more laminated batteries are arranged side by side, it is preferable to wrap all the sealing portions 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 seal portion 107 'located at the end and located at a portion where there is no adjacent laminated battery is also folded or wound in order to reduce the size of the battery pack and improve the volume energy density. Is preferred.
[0015]
The assembled battery 101 in FIG. 1 is overlapped with the seal portion 107 of the laminate battery 103 disposed adjacent to the plane direction, but may be overlapped with the seal portion of the laminate battery stacked in the vertical direction. Good (not shown). Such an embodiment is also encompassed in the concept of “the laminated battery adjacent to one laminated battery is overlapped”. Moreover, depending on the case, the sealing part of the laminated battery laminated | stacked on the 3 or more perpendicular direction may be rolled up.
[0016]
A battery that is small and excellent in volume energy density is particularly meaningful when the battery mounting space is limited. For example, the use of the assembled battery of the present invention is significant in applications where the demand for downsizing of the battery mounting space such as a vehicle is particularly strong.
[0017]
The overlapping winding shape of the seal part of the laminate 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 rectangle, or a triangle. Preferably, the shape when observed from the side of the laminated battery is a circle or an ellipse. If winding is performed so that there is no square portion such as a circle or an ellipse, the force applied to the seal portion is dispersed and the seal portion is prevented from being damaged.
[0018]
Preferably, the seal portion of the laminate sheet 105 of one laminate battery and the seal portion of the laminate sheet 105 ′ of the laminate battery adjacent to the one laminate battery are circles having a hollow portion as shown in FIG. It is preferable to be rolled up in a columnar shape. In the present application, the “cylindrical shape having a hollow portion” means a state in which the sealing portion of the laminated battery is wound so that a space is generated in the central portion. Further, in the present application, the “cylindrical shape” is a concept including not only a perfect cylinder but also a shape in which the cylinder is crooked.
[0019]
If the seal part 107 to be lap-wound is cylindrical, as described above, the force applied to the seal part is dispersed, and damage to the seal part is prevented. In addition, when the wiring cord is inserted into the hollow portion, the space in which 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 an assembled battery 201 in which a seal portion 207 existing between two laminated batteries 203 and 203 ′ is overlapped and laminated in two layers. FIG. 3 is a side view of the assembled battery of FIG. 2 from the III direction. Tabs 209 for use in electrical connection are drawn out from the laminate battery 203, and are connected via the tabs 209. When an assembled battery is mounted, the voltage may be measured to manage the charge / discharge state of each battery, but if the seal part is overlaid in a cylindrical shape having a hollow part, Battery voltage measurement wiring 211 for measuring the voltage state of the laminate battery can be inserted. By inserting the seal portion 207 that is wound so as to have a hollow portion, the space occupied by the seal portion 207 can be effectively utilized. In addition, since it can be used as a wiring route for the battery voltage measurement wiring 211, the degree of freedom in designing the wiring installation is increased. Furthermore, the wiring can be simplified, and the work for wiring to the assembled battery becomes easy. Such a feature is effective when wiring is complicatedly arranged, such as an assembled battery including a large number of laminated batteries.
[0021]
Although the case where the wiring that penetrates the hollow portion existing in the seal portion 207 is the battery voltage measurement wiring has been described, the wiring that penetrates the hollow portion is not limited to the battery voltage measurement wiring. Wiring other than the battery voltage measurement wiring may be inserted, and 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 assembled battery of the present invention. For example, when the assembled battery of the present invention is mounted on an automobile, the wiring that passes through the hollow portion is selected from the control system wiring and the wiring connected to the sensor around the space where the assembled battery is arranged. The
[0022]
What is necessary is just to determine the magnitude | size of a hollow part according to the wiring which penetrates a hollow part. Considering that the diameter of the generally used wiring is 1 to 3 mm, the minor 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 seal portion of the laminated battery increases, and the volume energy density of the assembled battery decreases. 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 battery packs of the present invention are combined, it is preferable to stack the battery packs so that a portion of the laminated battery in which the sealing portion is overlapped (hereinafter also referred to as “overlap portion”) overlaps. That is, it is preferable that the one assembled battery and the other assembled battery are stacked such that the overlapped portion of one assembled battery and the overlapped portion of another assembled battery overlap. FIG. 3 is a side view of an embodiment in which an assembled battery including two laminated batteries is laminated in two layers. By arranging in this way, the dead space can be more efficiently reduced. Moreover, it is easy to shorten the length of wiring required for electrically connecting the laminated batteries.
[0024]
As described above, the seal portions of three or more laminated batteries may be wound in layers. In the case of combining four laminated batteries as shown in FIG. 3, when four seal parts are overwrapped, the two overwrapped parts in FIG. 3 can be combined (not shown). However, it should be noted that the larger the number of seal portions to be lap-wrapped, the larger the occupied volume of the lap-wrap portion.
[0025]
Examples of the laminate battery of the present invention include a lithium ion secondary battery, a polymer lithium battery, a nickel-hydrogen battery, and a nickel-cadmium battery. Of these, lithium ion secondary batteries excellent in output and energy density are preferable in consideration of applications as power sources for vehicles. When an assembled battery in which laminated batteries, which are lithium ion secondary batteries, are connected in series is used as a vehicle power supply, an assembled battery having an overall output voltage of about 400 V can be obtained.
[0026]
In the laminate battery of the present invention, materials such as battery elements, tabs, and laminate sheets may be known materials and are not particularly limited. For reference, the case where the laminate battery of the present invention is a lithium ion secondary battery will be briefly described below. However, the laminate battery of the present invention is not limited to the lithium ion secondary battery.
[0027]
[Positive electrode]
The positive electrode has a structure in which a positive electrode material is bound on both surfaces of a positive electrode current collector made of aluminum or the like. As the positive electrode material, 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; lithium And amorphous vanadium pentoxide containing), chalcogen compounds (titanium disulfide, molybdenum disulfide, etc.), and the like. Among these, lithium manganese oxide or lithium nickel oxide is preferable in consideration of output characteristics of the obtained lithium ion secondary battery.
[0028]
In order to improve conductivity, the positive electrode current collector may be bound together with a conductive material. Examples of the conductive material include artificial graphite, carbon black (for example, acetylene black), nickel powder, and the like.
[0029]
As the positive electrode current collector, for example, an aluminum expanded metal, an aluminum mesh, an aluminum punched metal, 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 bound to both surfaces of a negative electrode current collector made of copper or the like. As the negative electrode material, a carbon material that occludes and releases lithium ions can be used. As such carbon materials, natural graphite, artificial graphite, carbon black, activated carbon, carbon fiber, coke, organic precursors (eg, phenol resin, polyacrylonitrile, cellulose, etc.) were synthesized by heat treatment in an inert atmosphere. Examples include carbon. 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 material can be obtained by carbonizing a thermosetting resin. Incidentally, when an amorphous carbon 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, copper expanded metal, copper mesh, 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 such as polyethylene or polypropylene can be used, and the non-aqueous electrolyte is impregnated in the separator. The nonaqueous electrolytic solution is prepared by dissolving an electrolyte in a nonaqueous solvent. Nonaqueous solvents include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone (γ-BL ), Sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. Nonaqueous solvents may be used alone or in combination 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. Examples include lithium salts such as (LiCF ₃ SO ₃ ) and bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₃ ) ₂ ]. The amount of the electrolyte dissolved in the non-aqueous solvent is usually about 0.2 mol / L to 2 mol / L.
[0033]
Examples of the polymer that holds the nonaqueous electrolytic solution 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. In general, a polymer metal composite film in which a heat-fusible resin film, a metal foil, and a resin film having rigidity are laminated in this order is used.
[0035]
As the heat-fusible resin, for example, polyethylene (PE), ionomer, ethylene vinyl acetate (EVA), or the like can be used. As the metal foil, for example, Al foil or Ni foil can be used. As the resin having rigidity, for example, polyethylene terephthalate (PET), nylon or the like can be used. Specifically, PE / Al foil / PET laminated film laminated from the sealing surface side to the outer surface; PE / Al foil / nylon laminated film; Ionomer / Ni foil / PET laminated film; EVA / Al foil / A laminated film of PET; an ionomer / Al foil / PET laminated film or the like can be used. The heat-fusible resin film acts as a seal layer when the battery element is housed inside. A metal foil or a rigid resin film imparts moisture, breathability, and chemical resistance to the exterior material. The laminate sheet can be easily and reliably bonded 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 metals can also be used. Further, nickel can be most preferably used for the surface coating layer, but metal materials such as silver and gold can be used as well.
[0037]
Then, the manufacturing method of the assembled battery of this invention is demonstrated easily.
[0038]
First, a laminated battery is prepared. The shape and type of the laminate battery are not particularly limited. For example, when a laminate battery that is a lithium ion secondary battery is used, the laminate battery may be made of the above-described materials.
[0039]
Next, the sealing part of the laminated battery arrange | positioned adjacently is rolled up. One method of lap winding will be described with reference to FIG. First, the laminated batteries to be rolled are overlapped. When overlapping, if the surfaces over which the seal portion 307a protrudes are overlapped, the seal portion 307a can be easily wound and the convenience of work is high.
[0040]
There is no particular limitation on the method of lap winding. When winding in a cylindrical shape having a hollow portion, the seal portion is wound using a steel rod having a desired thin diameter, and after winding, the steel rod is pulled out so as to have a hollow portion of a predetermined size. A wound seal portion 307b can be formed. You may process by letting a seal part pass through the curling type | mold which has a predetermined curvature. Furthermore, if necessary, the seal portion located on the opposite side of the overlapped seal portion is also overlapped.
[0041]
The assembled battery in which the seal portion is wound in layers is electrically connected to form an assembled battery. The effect when the wiring is inserted through the hollow portion is as described above. Depending on the case, it may be possible to overlap and wrap using a wire inserted through the hollow portion.
[0042]
The second of the present invention is a vehicle on which the assembled battery is mounted. For reference, FIG. 5 shows a perspective view of a vehicle (automobile) 413 on which the assembled battery of the present invention is mounted. The assembled battery 401 mounted on the vehicle has a high volumetric energy density. For this reason, the occupation volume of the battery part in a vehicle can be made small, and the freedom degree of design is high. Moreover, it is also useful for securing a space for personnel and luggage on the vehicle.
[Brief description of the drawings]
FIG. 1 is a side view of an embodiment of an assembled battery of 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 assembled battery of FIG. 2 from the III direction.
FIG. 4 is a diagram showing an embodiment of a method for lap winding of a seal portion.
FIG. 5 is a perspective view of a vehicle equipped with the assembled battery of the present invention.
[Explanation of symbols]
101, 201, 401 ... battery assembly, 103, 203, 203 '... laminate battery, 105, 105' ... laminate sheet, 107, 107 ', 207, 307a, 307b ... seal part, 209 ... tab, 211 ... battery voltage measurement wiring, 413 ... automobile as a vehicle

Claims (5)

A battery pack comprising a plurality of laminated batteries in which battery elements are sealed inside a laminate sheet,
An assembled battery, wherein a seal part of one laminate battery and a seal part of a laminate battery adjacent to the one laminate battery are wound in layers.   2. The set according to claim 1, wherein the seal portion of the one laminate battery and the seal portion of the laminate battery adjacent to the one laminate battery are overlapped and wound in a cylindrical shape having a hollow portion. battery. The assembled battery according to claim 2 , wherein a wiring cord is inserted into the hollow portion. The wire cord is assembled battery according to claim 3, characterized in that the battery voltage measuring line.   A vehicle comprising the assembled battery according to any one of claims 1 to 4.

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