JP4793529B2 - Lithium ion battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lithium ion battery, and more particularly to a lithium ion battery in which predetermined positions of a negative electrode terminal and a positive electrode terminal are covered with an insulating film.
[0002]
[Prior art]
In recent years, due to great advances in electronic technology, portable electronic devices intended for general users have been reduced in size and weight, and lithium-ion batteries that are reduced in size and weight are frequently used as energy sources for these electronic devices. In particular, some lithium ion batteries that use a metal resin composite film as a package and are further reduced in size and weight have been put into practical use.
[0003]
A package made of a metal resin composite film is, for example, a metal foil core material made of aluminum foil, a polyester resin such as polyethylene terephthalate (PET) along the surface of the metal foil core material, a polyamide resin such as nylon, or a protection made of polyimide resin. A layer obtained by laminating a layer and a fusible resin layer having a metal adhesive property made of polyolefin resin such as polypropylene (PP) or polyethylene (PE) along the back surface of the metal foil core is used.
[0004]
When manufacturing a lithium ion battery using a metal resin composite film as a package, a negative electrode terminal 62 and a positive electrode terminal 63 are joined to a negative electrode 60 and a positive electrode 61, respectively, as shown in FIG. The power generation element 65 is formed by laminating the separator 64 on the substrate and winding it, for example, as shown by the arrow in FIG. 4 (see FIG. 5). The power generation element 65 is housed and sealed by folding a package 66 (see FIG. 6) at the center, thereby forming a lithium ion battery 70 shown in FIG.
[0005]
In the package 66, a metal resin composite film 67 formed in a rectangular shape is formed in advance with a depression corresponding to the shape of the power generating element 65 (that is, the accommodating portion 68) above the central bent portion 67A.
[0006]
After the power generation element 65 is disposed in the accommodating portion 68, the metal resin composite film 67 is bent at the center bent portion 67A, and the metal resin composite film above the bent portion 67A and the metal resin composite film below the center are joined. The power generation element 65 is sandwiched between them, and the three sides of the superimposed metal resin film 67 are heated to form the fusion allowances 67B, 67C, 67D. At this time, the metal negative electrode terminal 62 and the positive electrode terminal 63 are sandwiched by the fusion allowance 67D, and the fusion allowance 67D is melted and joined to the negative electrode terminal 62 and the positive electrode terminal 63.
[0007]
[Problems to be solved by the invention]
However, since the negative electrode terminal 62 and the positive electrode terminal 63 are made of metal, there is a limit in reliably bringing the fusion allowance 67D of the metal resin film 67 into close contact with the negative electrode terminal 62 and the positive electrode terminal 63. For this reason, it is conceivable that the electrolytic solution accommodated in the accommodating portion 68 leaks from the gap between the fusion allowance 67D and the negative electrode terminal 62 and the positive electrode terminal 63.
[0008]
In order to solve this problem, in Japanese Patent Laid-Open No. 2000-138057, as shown in FIG. 7, the resin sheets 80 are preliminarily heat-sealed with the negative electrode terminal 62 and the positive electrode terminal 63 covered with the resin sheet 80, As shown in FIG. 8, a technique is disclosed in which a resin sheet 80 is sandwiched between metal resin films 67 and heat-sealed so that the resin sheet 80 and the fusion allowance 67D are brought into close contact with each other.
[0009]
However, the contact surface 81 of the resin sheet 80 that is in contact with the negative electrode terminal 62 and the positive electrode terminal 63 is heated for the first time when the resin sheets 80 are heat-sealed, and the resin sheet 80 and the metal resin film 67 are bonded to each other. It is conceivable that the second heating is performed at the time of heat-sealing, and the contact surface 81 of the resin sheet 80 is roughened and the adhesion is decreased at the second heating. For this reason, there has been a demand for practical application of a lithium ion battery capable of reliably bringing the negative electrode terminal 62, the positive electrode terminal 63, and the metal resin film 67 into close contact with each other.
[0010]
The present invention has been made in view of the above problems, we and aims to provide a lithium ion battery can be reliably brought into close contact with the metal resin film negative terminal and positive terminal.
[0011]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention provides a power generation element including a separator, a negative electrode, and a positive electrode, a pair of terminals respectively joined to the negative electrode and the positive electrode, and A package that accommodates and seals the power generation element such that the open end of each terminal is exposed to the outside; a fusion allowance having a predetermined width dimension provided in the package; and an insulating coating that covers a predetermined position of each terminal The insulating coating is a pair of sheets that sandwich the upper and lower surfaces of each terminal, and the pair of insulating coatings are heat-sealed in advance in a state of covering the terminals. And the fusion allowance sandwiches the insulating coating and the fusion-bonding portion by thermal fusion bonding the metal resin composite film of the package to the insulating coating, and the insulating coating. You The metal-resin composite film to the insulating film is characterized by comprising a non-fused portion is not fused with.
[0012]
In the lithium ion battery configured as described above, the contact surface between the negative electrode terminal and the positive electrode terminal and the respective insulating coatings can be prevented from being roughened by providing the non-fused portion in the fusion allowance. For this reason, a negative electrode terminal, a positive electrode terminal, and each insulating film can be stuck closely. Furthermore, by providing the fusion portion with the fusion allowance, the fusion allowance can be reliably adhered to the insulating coating.
[0013]
By the way, if the outer side of the fusion allowance is not brought into close contact with the insulating coating, for example, the fusion allowance may be peeled off from the outside during the transportation of the ion battery. Therefore, in order to prevent the fusion allowance from being peeled off from the outside, it is preferable to dispose the fusion portion on the outer side and to adhere the outer side of the fusion allowance to the insulating coating.
[0014]
Therefore, in the present invention, as described in claim 2, the width dimension of the fusion part is 1 mm or more, and the inner side end part of the insulating coating is separated from the fusion part by 2 mm or more. It is characterized by being.
[0015]
If the width dimension of the fused part is less than 1 mm, the width dimension of the fused part is too small, and there is a possibility that the electrolyte solution diffuses and permeates through the fused part and leaks to the outside. Therefore, the width dimension of the fused part is set to 1 mm or more so as to prevent diffusion and permeation of the electrolytic solution. In addition, in order to obtain a practically sufficient airtightness between the terminal and the insulating coating, the adhesion area of the insulating coating with respect to the terminal is required to be greater than a certain value. If it is less than 2 mm, the total width dimension of the insulating coating becomes small, so it is difficult to secure a desired area. For this reason, this inconvenience was avoided by setting the inner side end portion of the insulating coating to 2 mm or more from the fused portion.
[0016]
[0017]
Here, as the insulating film, when the width dimension of the insulating film substantially matches the width dimension of the fusion allowance, a structure in which a part of the insulating film is not fused in advance to the terminal, or In forming the fusion allowance, a structure in which a part of the insulating coating is not fused to the metal resin composite film can be exemplified. In addition, the insulating coating has a structure in which the width dimension of the insulating coating is set larger than the width dimension of the fusion allowance in advance, and a fusion allowance having a constant width dimension is formed to project into the package. It may be adopted.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. In each embodiment described below, the members and the like described in FIG. 1 are simplified or omitted by giving the same reference numerals or equivalent reference numerals in the drawings.
[0019]
As shown in FIG. 1, a lithium ion battery 10 according to a first embodiment of the present invention includes a power generation element 14 including a negative electrode 11 and a positive electrode 12, a negative electrode terminal 15 bonded to the negative electrode 11 and the positive electrode 12, and The positive electrode terminal 16, the package 20 that houses and seals the power generation element 14 so that the open end portion 15A of the negative electrode terminal 15 and the open end portion 16A of the positive electrode terminal 16 are exposed to the outside, and the package 20 so as to surround the power generation element 14 Insulation for negative electrode terminals that are provided on the periphery and have fusion widths 24, 25, 26 having a predetermined width dimension and predetermined positions 15 B, 16 B of the negative electrode terminal 15 and the positive electrode terminal 16 and are sandwiched between the fusion allowances 26. A coating 27 and an insulating coating 28 for positive terminal are provided.
[0020]
The power generation element 14 has a separator 13 interposed between the negative electrode 11 and the positive electrode 12 and is wound in an approximately elliptical shape, and the separator 13 is formed from the negative electrode 11 and the positive electrode 12 at both axial end portions 14A of the power generation element 14. Is also protruding.
[0021]
In the package 20, a metal resin composite film 21 formed in a rectangular shape is formed in advance with a depression corresponding to the shape of the power generation element 14 (that is, the accommodating portion 23) above the central bent portion 22.
[0022]
As shown in FIG. 2, the metal resin composite film 21 includes, as an example, a metal foil core material 21A made of aluminum foil, a protective layer 21B made of resin metal along the surface of the metal foil core material 21A, and a metal foil core material. A laminate in which a fusible resin layer 21C having a resin metal adhesion along the back surface of 21A is laminated is often used.
[0023]
The insulating film 27 is a pair of sheets that sandwich the upper and lower surfaces of the negative electrode terminal 15, and a resin-made film having metal adhesiveness is often used. The insulating coating 28 is a pair of sheets that sandwich the upper and lower surfaces of the positive electrode terminal 16, and a resin-made coating having metal adhesiveness is often used. The insulating coatings 27 and 28 are heat-sealed in advance with the pair of insulating coatings 27 and the pair of insulating coatings 28 in a state where the negative electrode terminal 15 and the positive electrode terminal 16 are covered.
[0024]
In the fusion allowances 24, 25, and 26 shown in FIG. 1, after the power generation element 14 is arranged in the accommodating portion 23, the metal resin composite film 21 is bent at the bent portion 22, and the metal resin composite film above the bent portion 22 is And the metal resin composite film below from the bent portion 22 are overlapped to sandwich the power generating element 14, and the three sides of the overlapped metal resin film are heated.
[0025]
As shown in FIG. 2, the fusion allowance 26 includes a fusion part 26 </ b> A where the metal resin composite film 21 of the package 20 is fused to the insulating coatings 27 and 28, and a metal resin composite to the insulating coatings 27 and 28. The film 21 includes a non-fused portion 26B to which the film 21 is not fused, and the fused portion 26A is provided on the outer side of the insulating coatings 27 and 28. That is, when the fusion allowance 26 is heat-sealed, only the fusion part 26A is heated and pressurized as shown by an arrow, and the non-fusion part 26B is not heated and pressurized.
[0026]
By providing the non-fusion part 26B in the fusion allowance 26 in this way, it is possible to prevent the contact surfaces 27A and 28A between the negative electrode terminal 15 and the positive electrode terminal 16 and the respective insulating coatings 27 and 28 from being roughened. For this reason, the negative electrode terminal 15 and the positive electrode terminal 16 and the insulating coatings 27 and 28 can be securely adhered to each other. Further, by providing the fusion allowance 26 with the fusion part 26A, the fusion allowance 26 can be securely adhered to the insulating coatings 27 and 28 in the region of the fusion part 26A. Therefore, it is possible to prevent the electrolyte in the package 20 from leaking to the outside.
[0027]
By the way, if the outer side of the fusion allowance 26 is not brought into close contact with the insulating coatings 27 and 28, for example, the fusion allowance 26 may be peeled off from the outside during the transportation of the lithium ion battery 10. Therefore, the fusion part 26 is arranged on the outer side, and the outer side of the fusion allowance 26 is brought into close contact with the insulating coatings 27 and 28, thereby preventing the fusion allowance 26 from being peeled from the outside. .
[0028]
The fusion allowance 26 has a width dimension L, and the fusion part 26A has a width dimension L1 of 1 mm or more. In addition, the inner end portions 26C of the insulating coatings 27 and 28 are set so as to be separated from the fused portion 26A by L2 = 2 mm or more.
[0029]
If the width L1 of the fused portion 26A is less than 1 mm, the width of the fused portion 26A is too small, and the electrolyte may leak to the outside by being diffused and transmitted through the fused portion 26A. Accordingly, the width L1 of the fused portion 26A is set to 1 mm or more so as to prevent the electrolyte from diffusing and transmitting.
[0030]
In order to obtain practically sufficient airtightness between the negative electrode terminal 15 and the positive electrode terminal 16 and the insulating coatings 27 and 28, the adhesion area of the insulating coatings 27 and 28 with respect to the negative electrode terminal 15 and the positive electrode terminal 16 is more than a certain value. Although it is necessary, if the inner side end portions of the insulating coatings 27 and 28 are less than 2 mm from the fused portion 26A, the total width dimension of the insulating coatings 27 and 28 becomes small, so that it is difficult to secure a desired area. For this reason, this inconvenience was avoided by setting the inner side end portions of the insulating coatings 27 and 28 to 2 mm or more from the fused portion 26A.
[0031]
[0032]
[0033]
[0034]
[0035]
[0036]
[0037]
Further, the lithium ion battery shown in FIG. 9 is also included in the present invention. That is, in the lithium ion battery 10A of the second embodiment shown in FIG. 9, the width dimensions of the insulating coatings 27 and 28 substantially coincide with the width dimension L of the fusion allowance 26, and the negative electrode terminal 15 and the positive electrode terminal 16 are previously A part of the insulating coatings 27 and 28 is not fused, and a part of the insulating coatings 27 and 28 is not fused to the metal resin composite film 21 when forming the fusion allowance 26. 26B is formed.
[0038]
[0039]
[0040]
[0041]
[0042]
[0043]
In each of the above-described embodiments, an example in which the power generation element is wound with the negative electrode terminal and the positive electrode terminal joined to the negative electrode and the positive electrode, respectively, and a separator interposed between the negative electrode and the positive electrode has been described. In an electrolyte lithium ion secondary battery, since a solid electrolyte layer is formed between the negative electrode and the positive electrode, there is little possibility of short circuit between them, and a configuration in which a separator is not provided between the negative electrode and the positive electrode is also possible. Good.
[0044]
Furthermore, the present invention is not limited to the above-described embodiment, and appropriate modifications, improvements, and the like are possible. The power generation element, positive electrode terminal, negative electrode terminal, insulating coating, package, and the like exemplified in the above-described embodiment The material, shape, dimensions, form, number, location, thickness, etc. are arbitrary as long as the present invention can be achieved, and are not limited.
[0045]
【The invention's effect】
As described above, according to the present invention, as described in claim 1, predetermined positions of the negative electrode terminal and the positive electrode terminal are each coated with an insulating film, and a fusion allowance for sandwiching the insulating film is a fusion part. And non-fused parts.
[0046]
By providing the non-fusion part in the fusion allowance, it is possible to prevent the contact surfaces between the negative electrode terminal and the positive electrode terminal and the respective insulating coatings from being roughened. For this reason, a negative electrode terminal, a positive electrode terminal, and each insulating film can be stuck closely. Furthermore, by providing the fusion portion with the fusion allowance, the fusion allowance can be reliably adhered to the insulating coating. Therefore, the electrolyte in the package can be prevented from leaking outside.
[0047]
By the way, if the outer side of the fusion allowance is not brought into close contact with the insulating coating, for example, the fusion allowance may be peeled off from the outside during transport of the lithium ion battery. In view of this, the fusion part is disposed on the outer side and the outer side of the fusion allowance is brought into close contact with the insulating coating to prevent the fusion allowance from being peeled off from the outside.
[0048]
Further, according to the present invention, as described in claim 2, when the width dimension of the fused portion is less than 1 mm, the width dimension of the fused portion is too small, and the electrolyte solution diffuses through the fused portion. There is a risk of leakage to the outside due to permeation. Therefore, the width dimension of the fused part is set to 1 mm or more so as to prevent diffusion and permeation of the electrolytic solution.
[0049]
In addition, if the inner end of the insulating coating is less than 2 mm from the fused portion, practically sufficient airtightness cannot be obtained between the terminal and the insulating coating. This problem was avoided by setting it to 2 mm or more from the fused part.
[0050]
[Brief description of the drawings]
FIG. 1 is a perspective view showing a lithium ion battery according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a principal part showing a lithium ion battery according to a first embodiment of the present invention.
FIG. 3 is a first explanatory view showing a method of manufacturing a conventional lithium ion battery.
FIG. 4 is a second explanatory view showing a method of manufacturing a conventional lithium ion battery.
FIG. 5 is a third explanatory view showing a method of manufacturing a conventional lithium ion battery.
FIG. 6 is a fourth explanatory view showing a method of manufacturing a conventional lithium ion battery.
FIG. 7 is a fifth explanatory view showing a method of manufacturing a conventional lithium ion battery.
FIG. 8 is a sixth explanatory view showing a method of manufacturing a conventional lithium ion battery.
FIG. 9 is a cross-sectional view of a principal part showing a lithium ion battery according to a second embodiment of the present invention.
[Explanation of symbols]
10,10A, 10B Lithium ion battery
11 Negative electrode
12 Positive electrode
13 Separator
14 Power generation elements
14A Both ends of the power generation element in the axial direction
15 Negative terminal
15A Open end of negative terminal
15B Predetermined position of negative terminal
16 Positive terminal
16A Open end of positive terminal
16B Positive position of positive terminal
20 packages
21 Metal resin composite film
24, 25, 26 Fusion allowance
25A, 26A Insulation coating edge
26A Fusion part
26B Non-fused part
26C Inner side edge
27, 28 Insulation coating

Claims (3)

A power generation element including a separator, a negative electrode, and a positive electrode; a pair of terminals respectively joined to the negative electrode and the positive electrode; and a package that accommodates and seals the power generation element so that an open end of each terminal is exposed to the outside. A lithium ion battery comprising a fusion allowance having a predetermined width dimension provided on the package and an insulating film covering a predetermined position of each terminal, wherein the insulating film includes upper and lower surfaces of each terminal. And a pair of insulating coatings that are heat-sealed in advance in a state of covering the terminals, the fusion allowance sandwiching the insulating coating and the insulating coating In contrast, the metal resin composite film of the package is fused by heat fusion, and the insulating coating is sandwiched and the metal resin composite film is not fused to the insulating coating. Lithium-ion batteries, characterized in that it comprises a wear part. 2. The lithium ion battery according to claim 1, wherein a width dimension of the fusion part is 1 mm or more, and an inner side end part of the insulating coating is 2 mm or more away from the fusion part. A power generation element including a separator, a negative electrode, and a positive electrode; a pair of terminals respectively joined to the negative electrode and the positive electrode; and a package that accommodates and seals the power generation element so that an open end of each terminal is exposed to the outside. A method of manufacturing a lithium ion battery comprising a fusion allowance having a predetermined width dimension provided in the package and an insulating film covering a predetermined position of each terminal, wherein the upper and lower surfaces of each terminal are previously A pair of sheets are covered with each other, and the pair of sheets are heat-sealed together to sandwich the upper and lower surfaces of each terminal with the insulating coating, and then the fusion allowance sandwiches the insulating coating. The fused portion where the metal-resin composite film of the package is fused to the insulating coating, and the metal-resin composite film is not fused to the insulating coating while sandwiching the insulating coating. As and a fused portion, a manufacturing method of a lithium ion battery, which comprises heat sealing said fusion Chakudai.

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