JP5217192B2 - battery - Google Patents

Description

The present invention relates to a battery in which a power generation element is housed in a battery case using a flexible film and filled with an electrolyte.

  Nonaqueous electrolyte secondary batteries that have been made thin and light by using an aluminum laminate film for the battery case have been widely used (see, for example, Patent Document 1). A configuration example of such a non-aqueous electrolyte secondary battery is shown in FIG. In this non-aqueous electrolyte secondary battery 1, a battery case 2 is composed of two rectangular aluminum laminate films 21, 22, and a power generation element 3 is housed inside the battery case 2 and filled with a non-aqueous electrolyte. Is done.

  The aluminum laminate films 21 and 22 are rectangular laminate films obtained by laminating both surfaces of an aluminum foil with a resin layer, and a concave portion is formed in most of the center excluding the peripheral portion. The aluminum laminate films 21 and 22 are overlapped from above and below with the concave portions facing each other, the power generation element 3 is sandwiched between them, filled with a nonaqueous electrolyte, and the peripheral portion is thermally welded, The battery case 2 is sealed. Further, the positive electrode lead terminal 4 and the negative electrode lead terminal 5 protruding from both end faces of the power generating element 3 are sealed through the overlap between the two aluminum laminate films 21 and 22 so as to protrude to the outside. .

  In the non-aqueous electrolyte secondary battery 1, when an extremely large external force or impact is applied, the flexible aluminum laminate films 21 and 22 may be damaged and the internal non-aqueous electrolyte may leak out. When the conductive non-aqueous electrolyte leaks outside and spreads around, there is a risk that a nearby wiring, a circuit board or the like will cause a short circuit.

  Therefore, conventionally, there has been a case where an electrolyte absorbent is applied to the outer surface of the aluminum laminate films 21 and 22 used in the battery case 2 of the nonaqueous electrolyte secondary battery 1 to form an electrolyte absorbent layer. The electrolytic solution absorbent is a resin that gels by absorbing the nonaqueous electrolytic solution. Therefore, even if the non-aqueous electrolyte leaks from the inside of the battery case 2 of the non-aqueous electrolyte secondary battery 1, the electrolyte absorbent layer formed on the outer surface of the aluminum laminate films 21 and 22 absorbs and gels. Therefore, this non-aqueous electrolyte can be prevented from spreading and spreading to the surroundings.

  However, the electrolyte absorbent layer swells on the outer surface of the aluminum laminate films 21 and 22 when it absorbs the non-aqueous electrolyte and gels. Thus, there is a problem of scattering around the non-aqueous electrolyte secondary battery 1. When the electrolyte absorbent layer swollen by the non-aqueous electrolyte peels off and scatters, it not only is unsightly but also smells, and if it enters between the terminals of the circuit board, a short circuit may occur.

  Moreover, since the electrolytic solution absorbent layer has a certain amount of hygroscopicity, the ability to absorb the nonaqueous electrolytic solution is reduced by absorbing moisture in the outside air. For this reason, when a long time has passed since the nonaqueous electrolyte secondary battery 1 was manufactured or when it is used in a high humidity environment, the electrolyte absorbent layer cannot sufficiently absorb the nonaqueous electrolyte. There was also a problem.

The above problem is not limited to the case where the aluminum laminate films 21 and 22 are used for the battery case 2, and the same problem occurs when other flexible films are used.

Further, even in the case of a battery using a water-soluble electrolytic solution, the situation is the same in that it must be prevented from spreading to the surroundings when the conductive electrolytic solution leaks out. Moreover, even when an electrolyte absorbent that gels by absorbing this water-soluble electrolyte is used, the electrolyte absorbent that has absorbed and gelled and swelled by the electrolyte is brittlely peeled off by vibration, impact, etc. The problem of scattering in the air occurs, and the ability to absorb the electrolytic solution decreases by absorbing moisture in the outside air.
Japanese Patent Laying-Open No. 2005-209587 (2nd page, FIG. 4)

In the present invention, an electrolytic solution absorbent that has swollen by absorbing an electrolytic solution is formed from the battery case by forming an electrolytic solution absorbent layer and a sealing agent layer in this order on the outer surface of the battery case using a flexible film. It is an object of the present invention to provide a battery that has no fear of peeling off and scattering around.

The battery according to claim 1 is characterized in that an electrolyte solution absorbent layer is formed on the outer surface of a battery case using a flexible film, and a seal agent layer is formed on the outer surface of the electrolyte solution absorbent layer.

According to the invention of claim 1, even if the electrolyte solution absorbent layer formed on the outer surface of the battery case using the flexible film absorbs the electrolyte solution and gels and swells, the seal layer is further formed on the outer layer side. Since it covers, it does not peel off from the outer surface of the battery case. In addition, since the electrolytic solution absorbent layer is usually covered with the sealing agent layer and moisture in the outside air is blocked, the ability to absorb the electrolytic solution with time does not decrease. .

  As an example of the above invention, in a non-aqueous electrolyte secondary battery using a flexible film for a battery case, an electrolyte absorbent layer is formed on the outer surface of the flexible film of the battery case, and the electrolyte absorbent layer A nonaqueous electrolyte secondary battery in which a sealing agent layer is formed on the outer surface can be mentioned.

  According to this non-aqueous electrolyte secondary battery, even if the electrolyte absorbent layer formed on the outer surface of the flexible film of the battery case absorbs the non-aqueous electrolyte and gels and swells, the outer layer side is further sealed Since the layer covers, it does not peel off from the outer surface of the flexible film. In addition, since this electrolyte absorbent layer is normally covered with a sealing agent layer and moisture in the outside air is blocked, the ability to absorb non-aqueous electrolyte decreases with the passage of time. Nor.

  In particular, non-aqueous electrolytes are not only conductive, but also have a stronger odor than water-soluble electrolytes, and battery cases using flexible films are damaged when subjected to extremely large external forces or impacts. Since the risk of leakage of the non-aqueous electrolyte is increased, the need to prevent the electrolyte absorbent layer that has absorbed the leaked non-aqueous electrolyte from peeling off increases.

  Hereinafter, the best embodiment of the present invention will be described with reference to FIGS. In these drawings, the same reference numerals are given to constituent members having the same functions as those of the conventional example shown in FIG.

  In the present embodiment, a non-aqueous electrolyte secondary battery 1 similar to the conventional example shown in FIG. 3 will be described. As shown in FIG. 1, the nonaqueous electrolyte secondary battery 1 of the present embodiment houses a power generation element 3 in a battery case 2 using two aluminum laminate films 21 and 22 and a nonaqueous electrolyte solution. Is filled.

  As shown in FIG. 2, the aluminum laminate films 21 and 22 are formed on one surface of the aluminum foil layers 21a and 22a on the base resin layers 21b and 22b having high barrier properties and strength such as nylon and PET (polyethylene terephthalate). And a flexible film having a three-layer structure in which thermoplastic resin layers 21c and 22c such as polypropylene (PP) and polyethylene (PE) are laminated on the other surface. In addition, as shown in FIG. 1, these aluminum laminate films 21 and 22 are previously formed by pressing in the most part of the center excluding the rectangular sheet-like peripheral edge portion by recessing the thermoplastic resin layers 21c and 22c. Has been.

  The two aluminum laminate films 21 and 22 are overlapped from above and below with the concave portions with the thermoplastic resin layers 21c and 22c facing each other, and the power generation element 3 is accommodated between them, and the peripheral thermoplasticity By thermally welding the resin layers 21c and 22c, the battery case 2 with the inside sealed is obtained. Further, the positive electrode lead terminal 4 and the negative electrode lead terminal 5 projecting from the front and rear end faces of the power generation element 3 are sealed between the front and rear edges of the two aluminum laminate films 21 and 22 so as to project to the outside. It has become. The non-aqueous electrolyte is injected before these aluminum laminate films 21 and 22 completely seal the inside.

  The nonaqueous electrolyte secondary battery 1 shown in FIG. 1 absorbs electrolyte solution on the outer surfaces of the aluminum laminate films 21 and 22 (outer surfaces of the base resin layers 21b and 22b) of the battery case 2 as shown in FIG. The agent layer 6 is formed, and the sealing agent layer 7 is further formed on the outer surface of the electrolyte solution absorbent layer 6. At this time, the electrolytic solution absorbent layer 6 and the sealing agent layer 7 are not only the outer surfaces of the base resin layers 21b and 22b in the aluminum laminate films 21 and 22, but also the aluminum foil layers 21a and 22a and the thermoplastic resin layer 21c. , 22c may also cover the outer surface of the end face of the heat-welded part that is exposed.

  The electrolyte solution absorbent layer 6 is a resin layer that gels by absorbing a non-aqueous electrolyte, and is formed by applying and curing an electrolyte solution absorbent on the outer surfaces of the aluminum laminate films 21 and 22. As the electrolyte absorbent, for example, a resin having a silyl group at the end can be used. When the electrolyte absorbent is formed on the outer surface of the flexible aluminum laminate films 21 and 22 as in the present embodiment, it is elastic even after curing. It is preferable to use what is provided. In addition, if a moisture curable resin is used, it can be easily cured by reacting with moisture in the outside air after application. In this embodiment, TB1530D manufactured by Three Bond Co., Ltd. was used as such an electrolyte absorbent.

  The sealing agent layer 7 is a resin layer having moisture resistance and chemical resistance, so that when the electrolyte solution absorbent layer 6 swells by absorbing a non-aqueous electrolyte, it is not torn. It is preferable to have a certain degree of elasticity. The sealant layer 7 is formed by applying a sealant to the outer surface of the electrolyte solution absorbent layer 6 and curing it. As the sealing agent, for example, styrene resin, silicone resin, or the like can be used. In addition, if a moisture curable resin is used, it can be easily cured by reacting with moisture in the outside air after application. In this embodiment, TB2905 manufactured by ThreeBond Co., Ltd. was used as such a sealant.

  In the non-aqueous electrolyte secondary battery 1 having the above-described configuration, when an extremely large external force or impact is applied, the flexible aluminum laminate films 21 and 22 of the battery case 2 are damaged and the non-aqueous electrolyte solution inside leaks. is there. Then, the non-aqueous electrolyte leaked from the aluminum laminate films 21 and 22 is directly absorbed by the electrolyte absorbent layer 6 at the leaked portion, or once overflows to the outside and this seal from the outer surface of the sealant layer 7. It passes through the agent layer 7 and reaches the electrolyte absorbent layer 6 on the inner layer side and is absorbed. Since the sealing agent layer 7 is softened and dissolved to some extent with respect to the non-aqueous electrolyte solution made of a liquid organic solvent, if the non-aqueous electrolyte solution adheres to the outer surface, the non-aqueous electrolyte solution is allowed to penetrate inside. Become.

  For example, when a plurality of non-aqueous electrolyte secondary batteries 1 are used in a stacked manner, if any non-aqueous electrolyte leaks from any of the non-aqueous electrolyte secondary batteries 1, the non-aqueous electrolyte is It adheres to the battery case 2 of another normal nonaqueous electrolyte secondary battery 1, passes through the sealing agent layer 7 from the outer surface of the sealing agent layer 7, and is absorbed into the electrolyte absorbent layer 6 on the inner layer side. The

  When the electrolyte solution absorbent layer 6 gels by absorbing the nonaqueous electrolyte solution as described above, it swells on the outer surface of the battery case 2. However, since the electrolytic solution absorbent layer 6 is covered with the sealing agent layer 7, it does not peel off from the outer surface of the battery case.

  Further, in the non-aqueous electrolyte secondary battery 1, the electrolyte solution absorbent layer 6 is normally covered with the sealant layer 7 to block moisture in the outside air. The ability to absorb the water electrolyte does not decrease with the passage of time or in a high humidity environment.

  In addition, although the said embodiment demonstrated the case where the electrolyte solution absorber layer 6 and the sealing agent layer 7 were formed by apply | coating an electrolyte solution absorber and a sealing agent on the outer surface of the aluminum laminate films 21 and 22, these were demonstrated. The method of forming the electrolyte absorbent layer 6 and the sealant layer 7 is arbitrary, and the electrolyte absorbent or sealant is sprayed or the nonaqueous electrolyte secondary battery 1 is immersed in the electrolyte absorbent or sealant. You may make it form.

  Moreover, in the said embodiment, although the case where the electrolyte solution absorber layer 6 and the sealing agent layer 7 were formed so that all the outer surfaces of the aluminum laminate films 21 and 22 in the battery case 2 might be covered was shown, it is not necessarily the outer surface. It is not necessary to cover all of them, and the electrolytic solution absorbent layer 6 may be formed only on a part of the outer surface of the aluminum laminate films 21 and 22. In this case, the sealing agent layer 7 needs to be formed so as to reliably cover the outer surface of the electrolyte absorbent layer 6, and may be formed so as to cover the entire outer surfaces of the aluminum laminate films 21 and 22. .

  Moreover, in the said embodiment, although the case where the lead terminals 4 and 5 protrude from the both end surfaces of the electric power generation element 3 was shown, the positive and negative lead terminals 4 and 5 may protrude from both one end surfaces. Further, the lead terminals 4 and 5 may be drawn out from a portion other than the end face, for example, from the winding end portion of the electrode. Furthermore, the configuration of the power generation element 3 is also arbitrary, and is not limited to the illustrated flat winding type, and can be implemented in the same way even with a cylindrical or stacked power generation element 3.

  Moreover, although the case where the peripheral part of the two aluminum laminate films 21 and 22 was heat-welded was shown in the said embodiment, it replaced with heat welding and can also join by other methods, such as adhesion | attachment. Further, in the above embodiment, the case where the two aluminum laminate films 21 and 22 are overlapped to form the battery case 2 has been shown. However, for example, one aluminum laminate film is folded in two, or both end portions like an envelope are used. A battery case that is superposed at the center may be used, or a battery case in which an aluminum laminate film is formed into a bag shape in advance may be used.

Moreover, although the case where the aluminum laminated films 21 and 22 were used for the battery case 2 was shown in the said embodiment, it replaced with the aluminum foil layers 21a and 22a, and the metal foil laminated film using another metal foil layer may be used. it can. Further, the battery case 2 need not be a metal foil laminate film as long as it is a flexible film that can secure sufficient strength and barrier properties and can be surely sealed. It may consist of a raw material resin film.

  Moreover, although the said embodiment demonstrated the nonaqueous electrolyte secondary battery 1 using the nonaqueous electrolyte, this invention can be implemented also in the battery generally containing the battery using aqueous solution electrolyte. In the case of a battery using an aqueous electrolyte, the electrolyte absorbent layer 6 is a resin layer that absorbs the aqueous electrolyte and gels.

1 is a partial cross-sectional perspective view showing a configuration of a nonaqueous electrolyte secondary battery according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially enlarged longitudinal sectional view of an aluminum laminate film showing an embodiment of the present invention and having an electrolyte absorbent layer and a sealing agent layer formed on the outer surface. It is an assembly perspective view which shows a prior art example and shows the structure of a nonaqueous electrolyte secondary battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte secondary battery 2 Battery case 21 Aluminum laminated film 21a Aluminum foil layer 21b Base resin layer 21c Thermoplastic resin layer 22 Aluminum laminated film 22a Aluminum foil layer 22b Base resin layer 22c Thermoplastic resin layer 3 Power generation element 4 Positive electrode lead Terminal 5 Negative electrode lead terminal 6 Electrolyte absorbent layer 7 Sealant layer

Claims (1)

A battery characterized in that an electrolyte absorbent layer is formed on the outer surface of a battery case using a flexible film, and a sealing agent layer is formed on the outer surface of the electrolyte absorbent layer.

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