JP4269554B2 - Lithium ion polymer battery and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lithium ion polymer battery having an improved shape of a laminated portion of an electrode tab and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, many portable electronic devices such as a camera-integrated VTR, a mobile phone, and a portable computer have appeared, and their size and weight have been reduced. As portable power sources for these electronic devices, there is an increasing demand for thin batteries and foldable batteries, particularly secondary batteries, especially non-aqueous electrolyte secondary batteries (so-called lithium ion batteries).
[0003]
A lithium ion secondary battery is a battery using a lithium-containing compound as a positive electrode active material, a carbon-based material as a negative electrode active material, and a non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent, and has a high energy density. This is a typical secondary battery.
[0004]
However, when a thin lithium ion secondary battery is produced using a conventional non-aqueous electrolyte, the liquid inside leaks and there is a risk of affecting surrounding electronic components. Therefore, a solid electrolyte obtained by solidifying the electrolytic solution has been proposed.
[0005]
In particular, a gel-like solid electrolyte obtained by impregnating a matrix polymer with a non-aqueous electrolyte (hereinafter referred to as a gel electrolyte) has a level equivalent to that of the electrolyte because the electrolyte phase serves as a main path for ion conduction. Since high ion conductivity can be expected, development is being actively promoted.
[0006]
[Problems to be solved by the invention]
However, in the laminated conventional lithium ion polymer battery, when the positive electrode tab and the negative electrode tab (hereinafter, the positive electrode tab and the negative electrode tab are collectively referred to as an electrode tab) are lengthened, the positive electrode tab and the negative electrode tab However, the length of the electrode tab could not be increased because of the possibility of short-circuiting with a single battery.
[0007]
When the length of the electrode tab is short, for example, as shown in FIG. 11, when the positive electrode tab 30 and the negative electrode tab 31 are joined to the electrodes 22 and 23 of the printed circuit board 21 on which the protection circuit 20 or the like is arranged by soldering or the like. In addition, since the joining portion and the laminate portion are very close to each other, there is a problem in that when the joining portion is heated, the laminate portion is damaged by the heat. Further, there is a possibility that the laminated battery element is also affected by the high temperature. Therefore, in the conventional battery, when the electrode tab is joined to the printed circuit board 21, it is necessary to add the metal tab 32 as an auxiliary material between the printed circuit board 21 and the electrode tab.
[0008]
Further, in the conventional laminate type battery, in order to protect the electrolyte and the battery element from humidity, for example, a laminate portion of 3 mm or more is necessary. However, when the laminate portion is large, the dead space is correspondingly increased, which is disadvantageous in terms of volumetric efficiency of the battery.
[0009]
Furthermore, in the conventional laminate battery, since the moisture has entered from the laminate portion of the electrode tab, the tab width cannot be increased. Further, since the positional tolerance increases as the tab width increases, there is a manufacturing problem in positioning the welding of the electrode tab.
[0010]
The present invention has been proposed in view of such a conventional situation, and a lithium ion polymer battery capable of forming a long and thick electrode tab by improving the laminate shape of the electrode tab portion and its An object is to provide a manufacturing method.
[0011]
[Means for Solving the Problems]
In the lithium ion polymer battery of the present invention, a battery element in which a positive electrode to which a positive electrode tab is connected and a negative electrode to which a negative electrode tab is connected is laminated via a gel electrolyte, and is laminated in an exterior material. A lithium ion polymer battery in which a positive electrode tab and a negative electrode tab are drawn out, and an exterior material covers the vicinity of the respective tips of the positive electrode tab and the negative electrode tab, and between the drawn positive electrode tab and the negative electrode tab. A cut portion is formed in the outer packaging material of the laminate portion, and the cut portion is stamped by press molding .
[0012]
In the lithium ion polymer battery according to the present invention as described above, since the cut portion is formed in the outer packaging material of the laminate portion between the positive electrode tab and the negative electrode tab, the electrode tab can be secured while sufficiently securing the laminate portion. Can be long and thick.
[0013]
The method for producing a lithium ion polymer battery according to the present invention includes a battery element in which a positive electrode connected to a positive electrode tab and a negative electrode connected to a negative electrode tab are laminated via a gel electrolyte. Is a method of manufacturing a lithium ion polymer battery that is laminated in an exterior material while pulling out the outside, and forming the cut portion by punching out the exterior material of the laminate portion between the positive electrode tab and the negative electrode tab with a press. Features.
[0014]
In the method of manufacturing a lithium ion polymer battery according to the present invention as described above, the cut portion is formed in the outer packaging material of the laminate portion between the positive electrode tab and the negative electrode tab, so that the electrode tab is sufficiently secured while ensuring the laminate portion. Can be long and thick.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a lithium ion polymer battery to which the present invention is applied will be described in detail with reference to the drawings.
[0016]
One structural example of this lithium ion polymer battery 1 is shown in FIGS. As shown in FIG. 3, the lithium ion polymer battery 1 includes a strip-shaped positive electrode 2, a strip-shaped negative electrode 3 disposed to face the positive electrode 2, and a gel electrolyte layer 4 formed on the positive electrode 2 and the negative electrode 3. And a separator 5 disposed between the positive electrode 2 on which the gel electrolyte layer 4 is formed and the negative electrode 3 on which the gel electrolyte layer 4 is formed.
[0017]
The lithium ion polymer battery 1 includes a positive electrode 2 on which a gel electrolyte layer 4 is formed and a negative electrode 3 on which a gel electrolyte layer 4 is formed via a separator 5 and wound in a longitudinal direction. The electrode winding body 6 shown in FIG. 2 is covered and sealed with an exterior film 7 made of an insulating material. A positive electrode tab 8 is connected to the positive electrode 2, and a negative electrode tab 9 is connected to the negative electrode 3, and the positive electrode tab 8 and the negative electrode tab 9 are sandwiched between sealing portions that are peripheral portions of the exterior film 7. ing. Further, a resin film 10 is disposed in a portion where the positive electrode tab 8 and the negative electrode tab 9 are in contact with the exterior film 7.
[0018]
As shown in FIG. 5, in the positive electrode 2, positive electrode active material layers 2a containing a positive electrode active material are formed on both surfaces of the positive electrode current collector 2b. For example, a metal foil such as an aluminum foil is used as the positive electrode current collector 2b.
[0019]
As the positive electrode active material, lithium composite oxides such as lithium cobaltate, lithium nickelate, and spinel lithium manganate can be used. These lithium composite oxides may be used alone or in combination of two or more.
[0020]
Moreover, as shown in FIG. 6, the negative electrode 3 has a negative electrode active material layer 3a containing a negative electrode active material formed on both surfaces of a negative electrode current collector 3b. For example, a metal foil such as a copper foil is used as the negative electrode current collector 3b.
[0021]
As the negative electrode active material, a material that can be doped or dedoped with lithium can be used. As a material capable of doping and dedoping such lithium, lithium metal and an alloy thereof, a carbon material, or the like can be used. Specific examples of carbon materials include carbon blacks such as natural graphite, artificial graphite, pyrolytic carbons, cokes, acetylene black, glassy carbon, activated carbon, carbon fiber, organic polymer fired body, coffee bean fired body, A cellulose fired body, a bamboo fired body, etc. are mentioned.
[0022]
The gel electrolyte layer 4 contains an electrolyte salt, a matrix polymer, and a swelling solvent as a plasticizer.
[0023]
As the electrolyte salt, LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiBF ₄ , LiN (CF ₃ SO ₃ ) ₂ , C ₄ F ₉ SO ₃ Li, or the like can be used alone or in combination. Among them, it is preferable to use LiPF ₆ from the viewpoint of ion conductivity and the like.
[0024]
The matrix polymer is not particularly limited in chemical structure as long as the polymer alone or a gel electrolyte using the polymer exhibits an ionic conductivity of 1 mS / cm or more at room temperature. Examples of the matrix polymer include polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, polysiloxane compounds, polyphosphazene compounds, polypropylene oxide, polymethyl methacrylate, polymethacrylonitrile, polyether compounds, and the like. Alternatively, a material obtained by copolymerizing the above polymer with another polymer can be used. From the viewpoint of chemical stability and ionic conductivity, it is preferable to use a material in which the copolymerization ratio of polyvinylidene fluoride and polyhexafluoropropylene is less than 8% by weight.
[0025]
As swelling solvents, ethylene carbonate, propylene carbonate, γ-butyrolactone, acetonitrile, diethyl ether, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, dimethyl sulfoxide, 1,3-dioxolane, methyl sulfomate, 2 -Nonaqueous solvents such as methyltetrahydrofuran, tetrahydrofuran, sulfolane, 2,4-difluoroanisole, vinylene carbonate and the like can be used alone or in combination.
[0026]
In the lithium ion polymer battery 1, as shown in FIG. 1, a cut portion 12 is formed in the exterior film 7 of the laminate portion 11 between the positive electrode tab 8 and the negative electrode tab 9 drawn out from the laminate portion 11. Yes. By forming the cut portion 12 in the exterior film 7 of the laminate portion 11, the laminate portion 11 is also configured as a part of the electrode tab, and the electrode tab can be lengthened accordingly. Even if the electrode tab is lengthened, the base portion is covered with the laminate of the exterior film 7, so that it is difficult to bend, and the positive electrode tab 8 and the negative electrode tab 9 do not intersect with each other as a single battery.
[0027]
2 shows a state before punching, that is, a state in which the cut portion 12 is not formed in the exterior film 7. As will be described later, the cut portion 12 is formed by punching the exterior film 7 along the dotted line shown in FIG. 4 after the electrode winding body 6 is accommodated in the exterior film 7.
[0028]
By making the electrode tab sufficiently long, as shown in FIG. 7, even if the tip of the electrode tab is directly soldered to the printed circuit board 21, the connection portion and the battery body are separated from each other. The battery body is not affected by heat and does not impair the battery body's performance such as moisture resistance. Thereby, connection with the printed circuit board 21 becomes possible, without using a connection tab. Therefore, the connection tab material and the connection tab welding process which are conventionally required are not required, and the number of parts and man-hours can be reduced. Further, since the electrode tab is sufficiently long, a plurality of lithium ion polymer batteries 1 can be stacked and connected in parallel as shown in FIG. This eliminates the need for a connection tab, leading to a reduction in the number of parts.
[0029]
Moreover, in this lithium ion polymer battery 1, since the electrode tab is sufficiently long and sufficiently laminated, the electrode tab can be bent and used. FIG. 9 shows an example in which the positive electrode tab 8 and the negative electrode tab 9 are taken out from the opposite side like a normal cylindrical battery by bending the positive electrode tab 8 and the negative electrode tab 9 and bending them. Thereby, since the problem of insulation can be solved, it is possible to connect with a cheap and simple sheet metal tab without using a collective tab (a composite material of an insulator and a tab).
[0030]
Furthermore, in this lithium ion polymer battery 1, the electrode tab can be thickened by forming the cut portion 12 in the exterior film 7 of the laminate portion 11. This is because the base portion of the electrode tab is sufficiently covered with the laminate of the exterior film 7, so that moisture can be prevented from entering from the laminate portion 11 even if the electrode tab is thickened. Moreover, in this lithium ion polymer battery 1, since the laminate part 11 is effectively used, the dead space can be reduced while securing the sufficient laminate part 11, and the volume efficiency of the battery can be improved. it can.
[0031]
And the lithium ion polymer battery 1 which concerns on this Embodiment as mentioned above is manufactured as follows.
[0032]
First, as the positive electrode 2, a positive electrode active material containing a positive electrode active material and a binder is uniformly coated on a metal foil such as an aluminum foil, for example, an aluminum foil to be the positive electrode current collector 2b, and then dried. The layer 2a is formed to produce a positive electrode sheet. As the binder of the positive electrode mixture, a known binder can be used, and a known additive or the like can be added to the positive electrode mixture.
[0033]
Next, the positive electrode sheet is cut into a strip shape. Then, for example, an aluminum lead wire is welded to the non-formed portion of the positive electrode active material layer 2 a to form the positive electrode tab 8. In this way, a belt-like positive electrode 2 as shown in FIG. 5 is obtained.
[0034]
In addition, the negative electrode 3 is formed by uniformly applying a negative electrode mixture containing a negative electrode active material and a binder onto a metal foil such as a copper foil to be the negative electrode current collector 3b and drying the negative electrode active material layer. 3a is formed and a negative electrode sheet is produced. As the binder of the negative electrode mixture, a known binder can be used, and a known additive or the like can be added to the negative electrode mixture.
[0035]
Next, the negative electrode sheet is cut into a strip shape. Then, a lead wire made of nickel, for example, is welded to a non-formation portion of the negative electrode active material layer 3a of the negative electrode current collector 3b to form a negative electrode tab 9. In this way, a strip-shaped negative electrode 3 as shown in FIG. 6 is obtained.
[0036]
Next, the gel electrolyte layer 4 is formed on the positive electrode active material layer 2a of the positive electrode sheet. In order to form the gel electrolyte layer 4, first, an electrolyte salt is dissolved in a non-aqueous solvent to prepare a non-aqueous electrolyte. Then, a matrix polymer is added to this non-aqueous electrolyte, and the mixture is stirred well to dissolve the matrix polymer to obtain a sol electrolyte solution.
[0037]
Next, a predetermined amount of this electrolyte solution is applied onto the positive electrode active material layer 2a. Subsequently, the matrix polymer is gelled by cooling at room temperature, and the gel electrolyte layer 4 is formed on the positive electrode active material 2a.
[0038]
Then, the belt-like positive electrode 2 and the negative electrode 3 manufactured as described above are bonded and pressed through the gel electrolyte layer 4 to obtain an electrode laminate. Furthermore, this electrode laminated body is wound in the longitudinal direction to obtain an electrode wound body 6 as shown in FIGS.
[0039]
Finally, as shown in FIG. 2 and FIG. 4, the electrode winding body 6 is sandwiched between exterior films 7 made of an insulating material, and the outer peripheral edge of the exterior film 7 is sealed, and a positive electrode tab 8 and a negative electrode tab 9. And the electrode wound body 6 are sealed in the exterior film 7. Further, the electrode winding body 6 is subjected to heat treatment in a state packed with the exterior film 7.
[0040]
Further, as shown in FIGS. 5 and 6, a resin film 10 is disposed in advance on the contact portion of the positive electrode tab 8 and the negative electrode tab 9 with the exterior film 7. As a result, a short circuit due to burrs or the like of the exterior film 7 is prevented, and the contact between the exterior film 7 and the positive electrode tab 8 and the negative electrode tab 9 is improved.
[0041]
The material of the resin film 10 is not particularly limited as long as it exhibits adhesion to the positive electrode tab 8 and the negative electrode tab 9, but polyethylene, polypropylene, modified polyethylene, modified polypropylene, and copolymers thereof, etc. It is preferable to use a polyolefin resin. Moreover, it is preferable that the thickness of the said resin film 10 is the range of 20 micrometers-300 micrometers by the thickness before heat sealing | fusion. When the thickness of the resin film 10 is less than 20 μm, the handleability is deteriorated, and when the thickness is more than 300 μm, moisture easily penetrates and it is difficult to maintain the airtightness inside the battery.
[0042]
Finally, as shown by a dotted line in FIG. 4, the laminate portion 11 from which the electrode tab is drawn out is punched out with a press, and a cut portion 12 is formed in the exterior film 7 of the laminate portion 11 between the positive electrode tab 8 and the negative electrode tab 9. Form. Finally, the lithium ion polymer battery 1 as shown in FIG. 1 is completed by folding the exterior film 7 on the side surface portion in the battery longitudinal direction.
[0043]
At this time, in the present invention, when the electrode tab portion is punched out by pressing, the electrode tab can be formed at the same time, so that the positional accuracy of the electrode tab can be remarkably improved. Conventionally, since the positional accuracy is not high, when welding a battery on a printed circuit board, the electrode tab and the welding area on the circuit board had to be made larger than the maximum tolerance. If the tab position accuracy is improved and the tolerance is reduced, the welding area can be reduced, and the wiring can be miniaturized. Conventionally, since the electrode position accuracy is not obtained, it is not suitable for continuous automatic welding. However, when the accuracy is obtained, automation is facilitated and productivity is improved.
[0044]
Moreover, when punching out the electrode tab portion with a press, it is necessary to punch out from a tab wider than the product size. However, in the prior art, if the tab width is wide, moisture enters from there, so that it cannot be easily widened. In the present invention, since the moisture-sealed laminate portion 11 can be set sufficiently long, it can be punched from a tab wider than the product size. In addition, as shown in FIG. 10, the electrode winding body 6 can also be enclosed using the exterior film 7 in which the cut | notch part was formed previously.
[0045]
In the above-described embodiment, the case where the belt-like positive electrode 2 and the belt-like negative electrode 3 are stacked and wound in the longitudinal direction to form the electrode winding body 6 has been described as an example. The present invention is not limited to this, and the present invention can also be applied to the case where the rectangular positive electrode 2 and the rectangular negative electrode 3 are laminated to form an electrode laminate, or the electrode laminate is folded alternately.
[0046]
The lithium ion polymer battery 1 according to the present embodiment as described above is not particularly limited in shape, and can be various sizes such as thin and large. The present invention can be applied to both a primary battery and a secondary battery.
[0047]
【The invention's effect】
In the present invention, by forming a cut portion in the outer packaging material of the laminate portion between the positive electrode tab and the negative electrode tab of the lithium ion polymer battery, the length of the electrode tab is increased while sufficiently securing the laminate portion, and Can be thick. As a result, in the present invention, the battery and the printed circuit board can be connected without using the connection tab, and the connection tab material and the connection tab welding process are not required, and the number of parts and man-hours can be reduced. .
Moreover, the position accuracy of the electrode tab can be dramatically improved by forming the electrode tab by stamping. Thereby, the welding area on the printed circuit board can be reduced. In addition, since the accuracy is improved, continuous automatic welding is facilitated, and productivity can be improved.
[0048]
In the present invention, since the laminate portion of the lithium ion polymer battery is effectively used, the dead space can be reduced and the volume efficiency of the battery can be improved while securing a sufficient laminate portion. .
[Brief description of the drawings]
FIG. 1 is a perspective view showing one structural example of a lithium ion polymer battery of the present invention.
FIG. 2 is a perspective view showing a state in which a battery element is accommodated in an exterior film.
FIG. 3 is a cross-sectional view taken along line AB in FIG.
FIG. 4 is a perspective view showing a state where battery elements are housed in an exterior film.
FIG. 5 is a perspective view showing a configuration of a positive electrode.
FIG. 6 is a perspective view showing a configuration of a negative electrode.
7A and 7B are a plan view and a side view showing how the lithium ion polymer battery of the present invention is connected to a printed board.
FIG. 8 is a side view showing a state in which two batteries are stacked and connected in parallel.
FIG. 9 is a side view showing a state in which the positive electrode tab and the negative electrode tab are bent out from the opposite direction.
FIG. 10 is a perspective view showing a state in which a battery element is accommodated in an exterior film in which cut portions are formed in advance.
FIGS. 11A and 11B are a plan view and a side view showing a state where a conventional lithium ion polymer battery is connected to a printed circuit board. FIGS.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lithium ion polymer battery, 2 Positive electrode, 3 Negative electrode, 4 Gel electrolyte layer, 5 Separator, 6 Electrode wound body, 7 Exterior film, 8 Positive electrode lead, 9 Negative electrode lead, 10 Resin film, 11 Laminate part, 12 Cut part

Claims (4)

A battery element in which a positive electrode to which a positive electrode tab is connected and a negative electrode to which a negative electrode tab is connected is laminated via a gel electrolyte, and is laminated in an exterior material, and the positive electrode tab and the above-described positive electrode tab and the above-described laminated portion are laminated. A lithium ion polymer battery in which a negative electrode tab is drawn out to the outside,
The exterior material covers the positive electrode tab and the negative electrode tab in the vicinity of their respective tips,
A cut portion is formed in the exterior material of the laminate portion between the drawn positive electrode tab and the negative electrode tab ,
The lithium ion polymer battery , wherein the cut portion is stamped by press molding .   The lithium ion polymer battery according to claim 1, wherein a resin film is disposed at a portion where the positive electrode tab and the negative electrode tab are in contact with the exterior material. A battery element in which a positive electrode to which a positive electrode tab is connected and a negative electrode to which a negative electrode tab is connected is laminated via a gel electrolyte, and the positive electrode tab and the negative electrode tab are pulled out and laminated in an exterior material. A method for producing a lithium ion polymer battery, comprising:
A method for producing a lithium ion polymer battery, wherein a cut portion is formed by punching out the outer packaging material of the laminate portion between the positive electrode tab and the negative electrode tab with a press. 4. The method for producing a lithium ion polymer battery according to claim 3 , wherein a resin film is disposed at a portion where the positive electrode tab and the negative electrode tab are in contact with the exterior material.

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