JP2006222018A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery that prevents moisture from entering a battery and maintains battery performance continuously.
SOLUTION: A lithium ion secondary battery includes a battery element 21 having a positive electrode sheet, a negative electrode sheet, and an electrolyte, and joint portions 26 and 27. The joint portions 26 and 27 are joined to each other, whereby the battery element 21 is joined. And a silicone rubber 31 for joining the joining portion 26 and the joining portion 27 to each other.
[Selection] Figure 2

Description

  The present invention generally relates to a secondary battery, and more particularly to a non-aqueous electrolyte secondary battery.

  Regarding a conventional secondary battery, for example, Japanese Patent Application Laid-Open No. 2003-187762 discloses a non-aqueous electrolyte battery for the purpose of preventing moisture from entering inside while suppressing the size (see FIG. Patent Document 1). In the nonaqueous electrolyte battery disclosed in Patent Document 1, a hygroscopic agent is disposed around the laminate outer package. The hygroscopic agent is formed from synthetic zeolite, silica gel, phosphorus pentoxide, barium oxide or calcium oxide.

  Japanese Patent Laid-Open No. 2002-63874 discloses a battery aimed at improving flexibility and volume density (Patent Document 2). In the battery disclosed in Patent Document 2, a tube-shaped exterior body that houses a power generation element is formed of silicon resin or the like. Japanese Patent Application Laid-Open No. 2000-182579 discloses a plate-shaped polymer electrolyte battery for the purpose of reducing the weight and size and improving the mechanical strength (Patent Document 3).

Japanese Patent Application Laid-Open No. 2004-228047 discloses a battery pack for the purpose of suppressing an increase in battery temperature (Patent Document 4). Japanese Patent Application Laid-Open No. 2000-195475 discloses a secondary battery for the purpose of realizing high productivity and excellent durability (Patent Document 5). Japanese Patent Application Laid-Open No. 11-67278 discloses a resin-sealed lithium ion secondary battery that achieves weight reduction and capacity increase and is manufactured at a lower cost (Patent Document 6). .
JP 2003-187762 A JP 2002-63874 A JP 2000-182579 A JP 2004-228047 A JP 2000-195475 A Japanese Patent Laid-Open No. 11-67278

  In the non-aqueous electrolyte battery disclosed in Patent Document 1, moisture that is to enter the inside of the laminate outer package is captured by a hygroscopic agent. However, when a hygroscopic agent made of silica gel, phosphorus pentoxide, barium oxide or the like is used, the moisture trapped in the hygroscopic agent remains in place. For this reason, with the passage of time, the moisture in the hygroscopic agent may be mixed into the electrolyte. In this case, when a certain amount of moisture is mixed, the electrolyte does not perform an appropriate function. It is also conceivable that after the moisture-proofing agent captures moisture, the compound is ionized and has a charge. In this case, there is a concern that a short circuit occurs inside the battery. In addition, the hygroscopic agent may absorb the electrolyte or the volatile component of the electrolyte.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a secondary battery that prevents moisture from entering the battery and maintains the battery performance continuously.

  A secondary battery according to the present invention has a battery element having a positive electrode sheet, a negative electrode sheet, and an electrolyte, and first and second joint portions, and the first and second joint portions are joined to each other. And a laminate outer body that forms a space for accommodating the battery element, and a silicone rubber that joins the first joint portion and the second joint portion.

  According to the secondary battery configured as described above, silicone rubber is used for joining the first joining portion and the second joining portion. Silicone rubber is cured by causing a chemical reaction with moisture in the air. For this reason, it can prevent reliably that a water | moisture content reaches | attains the battery element in a laminate exterior body between between a 1st junction part and a 2nd junction part with the hardened silicone rubber. In addition, the silicone rubber exhibits water repellency after being cured and does not absorb moisture any more. For this reason, there is no concern that the moisture trapped in the silicone rubber enters the battery element, and the battery performance of the secondary battery can be continuously maintained. Moreover, since silicone rubber has high electrical insulation, it can prevent an internal short circuit from occurring in the laminate outer package.

  Preferably, the silicone rubber is provided so as to cover the peripheral edges of the first and second joint portions and sandwich the first and second joint portions. According to the secondary battery configured as described above, first, moisture can be prevented from entering the laminate exterior body by the silicone rubber cured at the peripheral edges of the first and second joint portions. Moreover, the 1st and 2nd junction part is the state which mutually contact | adhered by being pinched | interposed into silicone rubber. For this reason, it can further prevent that a water | moisture content permeates into a laminate exterior body between a 1st junction part and a 2nd junction part.

  The electrolyte is a non-aqueous electrolyte. In the secondary battery configured as described above, since the mixing of water into the electrolyte directly leads to a decrease in the battery performance of the secondary battery, the present invention having the above-described effects can be used more effectively.

  As described above, according to the present invention, it is possible to provide a secondary battery that prevents moisture from entering the battery and maintains the battery performance continuously.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

(Embodiment 1)
1 is a perspective view showing a lithium ion secondary battery according to Embodiment 1 of the present invention. In the figure, a lithium ion secondary battery mounted on a hybrid vehicle and serving as a power source for the hybrid vehicle is shown together with an internal combustion engine such as a gasoline engine or a diesel engine. FIG. 2 is an exploded view of the lithium ion secondary battery along the line II-II in FIG. FIG. 3 is a cross-sectional view of the lithium ion secondary battery along the line III-III in FIG.

  With reference to FIGS. 1 to 3, the lithium ion secondary battery 10 includes a battery element 21 and a laminate outer package 25 provided so as to cover the battery element 21. Joined portions 26 and 27 are formed on the periphery of the laminate outer package 25 so as to face each other. Between the joint part 26 and the joint part 27, the silicone rubber 31 which joins these joint parts mutually is arrange | positioned. The space between the joint portion 26 and the joint portion 27 is sealed by the silicone rubber 31 to form a space 24 in which the battery element 21 is accommodated in the laminate outer package 25.

  The battery element 21 includes a positive electrode sheet and a negative electrode sheet wound in a stacked state with a separator interposed therebetween, and an electrolyte enclosed in the space 24 together with the positive electrode sheet and the negative electrode sheet. The electrolyte is an organic electrolyte obtained by dissolving a lithium salt in an organic solvent, and is a nonaqueous electrolyte.

  A positive electrode terminal 22 and a negative electrode terminal 23 are connected to the positive electrode sheet and the negative electrode sheet of the battery element 21, respectively. The positive terminal 22 and the negative terminal 23 are made of metal. For example, the positive terminal 22 is made of copper (Cu), and the negative terminal 23 is made of aluminum (Al). The positive electrode terminal 22 and the negative electrode terminal 23 have a plate shape. The positive electrode terminal 22 and the negative electrode terminal 23 are formed to extend from the space 24 through a position sandwiched between the joint portion 26 and the joint portion 27 and further to the outside of the laminate outer package 25. The positive electrode terminal 22 and the negative electrode terminal 23 are formed so as to extend in opposite directions around the battery element 21.

  The laminate outer package 25 is formed, for example, by coating a resin material such as polyethylene terephthalate (PET) on a base material made of metal such as aluminum. The laminate outer package 25 is formed such that one base material is folded and two sheets are overlapped. The joint portions 26 and 27 are formed so as to extend in a belt shape along three sides of a substantially rectangular shape that opens in a state where the two pieces overlap each other. In addition, you may form the laminate exterior body 25 using a cylindrical base material. In this case, the joint portions 26 and 27 are formed on opposite sides of a substantially rectangular shape.

  By forming the laminate outer package 25 using a metal such as aluminum as a base material, high strength can be obtained with a thin thickness. As a result, according to the laminate outer package 25, the battery weight can be reduced as compared with the case where the strength is ensured by the laminate package formed from the resin. Since the lithium ion secondary battery 10 mounted on the hybrid vehicle has a strong demand for weight reduction, the laminate outer package 25 using metal as a base material can be used particularly effectively. In addition, according to the laminate outer package 25, excellent heat dissipation can be obtained as compared with a laminate outer package formed from a resin.

  The joint portions 26 and 27 have joint surfaces 26a and 27a that face each other. The silicone rubber 31 is provided so as to be in contact with the joint surfaces 26a and 27a along the direction in which the joint portions 26 and 27 extend in a strip shape. The silicone rubber 31 is further provided so as to entirely surround the positive electrode terminal 22 and the negative electrode terminal 23 at a position where the positive electrode terminal 22 and the negative electrode terminal 23 are sandwiched between the joint portions 26 and 27. Silicone rubber 31 is provided in contact with positive electrode terminal 22 and negative electrode terminal 23.

  Since the positive electrode terminal 22 and the negative electrode terminal 23 have a predetermined thickness, when the joint portion 26 and the joint portion 27 are joined with the terminals interposed therebetween, a gap is easily formed around the terminals. On the other hand, the silicone rubber 31 exhibits excellent adhesion to metal and also exhibits excellent adhesion to the positive terminal 22 and the negative terminal 23. In the present embodiment, by providing the silicone rubber 31 so as to contact the positive electrode terminal 22 and the negative electrode terminal 23, it is possible to prevent a gap from being formed around the positive electrode terminal 22 and the negative electrode terminal 23.

The silicone rubber 31 is a moisture curable silicone rubber that cures by causing a chemical reaction with moisture in the air at room temperature. Since the silicone rubber 31 is excellent in durability against temperature, even when the lithium ion secondary battery 10 generates heat, it is possible to maintain a sealed state between the joint portion 26 and the joint portion 27. Moreover, the silicone rubber 31 is excellent in electrical insulation (volume resistivity 10 ^{14 to 15} Ω / cm). For this reason, there is no concern that the silicone rubber 31 absorbs water and energizes, and the occurrence of a short circuit can be prevented. Further, the silicone rubber 31 does not generate heat during curing. For this reason, it is excellent in safety and the handling at the time of manufacture of the lithium ion secondary battery 10 becomes easy.

  Further, the silicone rubber 31 exhibits water repellency after curing. That is, the silicone rubber 31 does not continue to absorb moisture (humidity), but is cured once it absorbs moisture, and then repels moisture (water does not permeate). For this reason, according to the present embodiment, the cured silicone rubber 31 can surely prevent moisture from entering the space 24 from the outside of the laminate outer package 25. Further, there is no concern that moisture will enter the space 24 from the silicone rubber 31 with the passage of time.

  Moreover, since the waterproofness of the laminate outer package 25 is secured by the silicone rubber 31, the lengths of the joint surfaces 26a and 27a (the length indicated by the dimension A in FIG. 1) can be set shorter. As a result, the dead space generated by the joint portions 26 and 27 can be reduced, and the lithium ion secondary battery 10 can be downsized.

  Further, the joint portions 26 and 27 are overlapped and joined to each other without being bent. That is, the joint portions 26 and 27 are formed so as to spread on the same plane. Thereby, the strength of the joint portions 26 and 27 does not decrease at the bent position, and the strength of the laminate outer package 25 can be maintained even during long-term use.

  A lithium ion secondary battery 10 as a secondary battery according to Embodiment 1 of the present invention includes a battery element 21 having a positive electrode sheet, a negative electrode sheet, and an electrolyte, and joint portions 26 and 27 as first and second joint portions. And the joint portions 26 and 27 are joined to each other to form a laminate outer body 25 that forms a space 24 that accommodates the battery element 21, and a silicone rubber 31 that joins the joint portion 26 and the joint portion 27. Prepare.

  The lithium ion secondary battery 10 is connected to the battery element 21 in the space 24, and passes from the space 24 between the joint portion 26 and the joint portion 27 to the positive electrode terminal 22 as a terminal protruding to the outside of the laminate outer package 25. And a negative electrode terminal 23. The silicone rubber 31 is provided between the joint portion 26 and the joint portion 27 so as to contact the positive electrode terminal 22 and the negative electrode terminal 23 and to surround the positive electrode terminal 22 and the negative electrode terminal 23.

  According to the lithium ion secondary battery 10 according to the first embodiment of the present invention configured as described above, the waterproofness of the laminate outer package 25 is improved by using the silicone rubber 31 for joining the joint portions 26 and 27. Can be made. Thereby, it is possible to prevent moisture from being mixed into the non-aqueous electrolyte sealed in the laminate outer package 25 and to maintain the electrical performance of the lithium ion secondary battery 10.

  The silicone rubber 31 may be provided in a part of a range where the joint portions 26 and 27 extend in a band shape, and the remaining portion of the range is joined by thermal welding between the joint portion 26 and the joint portion 27. May be.

  Moreover, the secondary battery accommodated in the laminate outer package 25 is not limited to the lithium ion secondary battery 10, and may be a nickel hydrogen battery, for example. In this case, the battery element constituting the nickel metal hydride battery is formed in a shape in which comb-like positive electrode sheets and negative electrode sheets arranged so as to face each other are alternately meshed with each other via the separator. A caustic potash aqueous solution is used as the electrolyte sealed in the laminate outer package 25. According to the present embodiment, since moisture can be prevented from entering the laminate outer package 25, the concentration of the caustic potash aqueous solution can be prevented and impurities contained in the moisture can be prevented from being mixed into the aqueous solution. . For this reason, as in the case of the lithium ion secondary battery 10, the battery performance of the nickel metal hydride battery can be maintained.

(Embodiment 2)
FIG. 4 is a cross-sectional view showing a lithium ion secondary battery according to Embodiment 2 of the present invention. Compared with lithium ion secondary battery 10 in Embodiment 1, the lithium ion secondary battery in the present embodiment basically has the same structure. Hereinafter, the description of the overlapping structure will not be repeated.

  Referring to FIG. 4, the position where the joint portions 26 and 27 of the laminate outer package 25 are overlapped is shown in an enlarged manner. The joint portion 26 has a surface 26b facing the side opposite to the joint surface 26a, and a peripheral surface 26c located at the end of the joint surface 26a and the surface 26b. The joint portion 27 has a surface 27b facing the side opposite to the joint surface 27a, and a peripheral surface 27c located at the end of the joint surface 27a and the surface 27b. The joint portions 26 and 27 are overlapped so that the peripheral surface 26c and the peripheral surface 27c extend on the same plane.

  In the present embodiment, a silicone rubber 33 is provided in place of the silicone rubber 31 in the first embodiment. The silicone rubber 33 is provided so as to cover the ends of the surfaces 26b and 27b and the peripheral surfaces 26c and 27c. With such a configuration, the overlap between the joint surface 26 a and the joint surface 27 a is closed by the silicone rubber 33. Further, the joint portion 26 and the joint portion 27 are sandwiched by the silicone rubber 33.

  According to the lithium ion secondary battery according to the second embodiment of the present invention configured as described above, the same effects as those described in the first embodiment can be obtained. In addition, in the present embodiment, the laminate outer body 25 is sandwiched between the silicone rubber 33 and the silicone rubber 33 covering the overlap between the joint surface 26a and the joint surface 27a between the inside and the outside. It is interrupted by both joints 26 and 27. For this reason, the waterproofness of the laminate outer package 25 can be further improved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a perspective view which shows the lithium ion secondary battery in Embodiment 1 of this invention. FIG. 2 is an exploded view of the lithium ion secondary battery along the line II-II in FIG. 1. It is sectional drawing of the lithium ion secondary battery along the III-III line in FIG. It is sectional drawing which shows the lithium ion secondary battery in Embodiment 2 of this invention.

Explanation of symbols

  10 lithium ion secondary battery, 21 battery element, 24 space, 25 laminate outer package, 26, 27 joint, 31, 33 silicone rubber.

Claims (3)

A battery element having a positive electrode sheet, a negative electrode sheet and an electrolyte;
A laminate outer body having first and second joints, wherein the first and second joints are joined together to form a space for housing the battery element;
A secondary battery comprising a silicone rubber that joins the first joint and the second joint.   2. The secondary battery according to claim 1, wherein the silicone rubber covers a periphery of the first and second joint portions and is provided so as to sandwich the first and second joint portions.   The secondary battery according to claim 1, wherein the electrolyte is a non-aqueous electrolyte.

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