Laminate-type power storage element and manufacturing method thereof

Abstract

A laminate-type power storage element, including an exterior body that is formed in a flat bag shape, and an electrode body that has a sheet-shaped positive electrode and a sheet-shaped negative electrode layered via a separator and that is sealed inside the exterior body together with an electrolytic solution, wherein electrode terminal plates of the positive electrode and the negative electrode are guided in an identical direction from a predetermined margin of the exterior body to an outside of the exterior body, and a support part that is made with a film shaped resin having insulating and heat-resistant properties is formed on principal surface sides of the electrode terminal plates at a region that is along the predetermined margin and covers up to tip ends of the electrode terminal plates.

Claims

1. A laminate-type power storage element, comprising: an exterior body that is formed in a flat bag shape; and an electrode body that has a sheet-shaped positive electrode and a sheet-shaped negative electrode layered via a separator and that is sealed inside the exterior body together with an electrolytic solution, wherein electrode terminal plates of the positive electrode and the negative electrode are guided in an identical direction from a predetermined margin of the exterior body to an outside of the exterior body such that levels of the electrode terminal plates on principal surface sides are made equal to each other, a support part that is made with a film shaped resin having insulating and heat-resistant properties is formed on the principal surface sides of the electrode terminal plates at a region that is along the predetermined margin and covers up to tip ends of the electrode terminal plates, so as to intersect the positive and negative electrodes, the support part being heated when the electrode terminal plates are implemented to a circuit board, and an anisotropic conductive film (ACF) is provided to a back face side of each of the principal surfaces of the electrode terminal plates, the anisotropic conductive film being thermally welded to an implementation surface of the circuit board when the laminate-type power storage element is implemented to the circuit board.

2. The laminate-type power storage element according to claim 1, wherein the support part is formed with resin having a moisture barrier property and covers in the predetermined margin a region where the electrode terminal plates are guided outside.

3. The laminate-type power storage element according to claim 1 that is used as a power supply of a card type electronic device incorporating an electronic circuit and the power storage element.

4. A method of manufacturing a laminate-type power storage element according to claim 1, comprising: preparing a laminate-type power storage element body that has an electrode body having a sheet-shaped positive electrode and a sheet-shaped negative electrode layered via a separator and an electrolytic solution sealed inside an exterior body that is formed in a flat bag shape, and that has electrode terminal plates of the positive electrode and the negative electrode guided in an identical direction from a predetermined margin of the exterior body to an outside; applying on a release sheet a resin that has insulating and heat-resistant properties and that is in an unhardened state; bridging the release sheet across the two electrode terminal plates of the positive and the negative electrodes in the power storage element body while making a face to which the resin is applied oppose principal surfaces of the electrode terminal plates and making the principal surfaces of the electrode terminal plates come into intimate contact with the face to which the resin is applied; hardening the resin while the principal surfaces of the electrode terminal plates are in states pressed against the face to which the resin is applied; separating the release sheet from the hardened resin to form a support part; and applying the anisotropic conductive film to each of the principal surfaces of the electrode terminal plates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings wherein:

(2) FIG. 1A is a drawing illustrating an example of a general laminate-type power storage element;

(3) FIG. 1B is a drawing illustrating an example of a general laminate-type power storage element;

(4) FIG. 2A is a drawing illustrating an implementation procedure for the laminate-type power storage element using an ACF;

(5) FIG. 2B is a drawing illustrating an implementation procedure for the laminate-type power storage element using an ACF;

(6) FIG. 2C is a drawing illustrating an implementation procedure for the laminate-type power storage element using an ACF;

(7) FIG. 2D is a drawing illustrating an implementation procedure for the laminate-type power storage element using an ACF;

(8) FIG. 3A is a drawing illustrating a support-type laminate-type power storage element;

(9) FIG. 3B is a drawing illustrating a support-type laminate-type power storage element;

(10) FIG. 3C is a drawing illustrating a support-type laminate-type power storage element;

(11) FIG. 4 is a drawing illustrating a method of implementing the support-type laminate-type power storage element;

(12) FIG. 5A is a drawing illustrating an external view of a laminate-type power storage element according to a working example of the present invention;

(13) FIG. 5B is a drawing illustrating an external view of a laminate-type power storage element according to a working example of the present invention;

(14) FIG. 6A is a drawing illustrating a structure of a laminate-type power storage element according to a working example of the present invention;

(15) FIG. 6B is a drawing illustrating a structure of a laminate-type power storage element according to a working example of the present invention;

(16) FIG. 7A is a drawing illustrating a manufacturing method of the laminate-type power storage element according to a working example of the present invention;

(17) FIG. 7B is a drawing illustrating a manufacturing method of the laminate-type power storage element according to a working example of the present invention;

(18) FIG. 7C is a drawing illustrating a manufacturing method of the laminate-type power storage element according to a working example of the present invention;

(19) FIG. 7D is a drawing illustrating a manufacturing method of the laminate-type power storage element according to a working example of the present invention; and

(20) FIG. 8 is a drawing illustrating a method of implementing the laminate-type power storage element according to a working example of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(21) The following describes working examples of the present invention with reference to the attached drawings. Like reference numerals designate corresponding or identical elements in the drawings used for the following description, and therefore such elements may not be further elaborated. While a reference numeral is assigned to a part in a drawing, if unnecessary, the reference numeral may not be assigned to the corresponding part in another drawing.

Working Examples

(22) Structure

(23) The laminate-type power storage element (hereinafter referred as power storage element) according to a working example of the present invention has a special configuration that serves in place of a support tab and is made to keep the electrode body from being damaged by a thermocompression bonding process as well as a short-circuit from being generated between the electrode terminals with this unique configuration. The inner structure of the power storage element according to the working example is similar to that of the power storage element 1 illustrated in FIG. 1B. FIGS. 5A, 5B, 6A and 6B illustrate a laminate-type power storage element (hereinafter also referred to as a power storage element 1a) according to the working example of the present invention. The following has each of the up-down, front-rear and right-left directions defined similar to FIGS. 3A to 3C. FIG. 5A is an external view of the power storage element 1a when seen from above and FIG. 5B is an external view of the power storage element 1a when seen from below. FIG. 6A is a drawing enlarging a front side of a cross section viewed from arrow c-c in FIG. 5A and FIG. 6B is a drawing enlarging the parts inside the circle 100 in FIG. 6A. As illustrated in FIGS. 5A and 5B, the power storage element 1a according to the working example includes a power storage element body 1 that has a structure similar to a common laminate-type power storage element 1 that does not have a support tab, which is shown in FIGS. 1A and 1B above. The back face side of the electrode terminal plates (23, 33) of this power storage element 1 has formed thereto a region (hereinafter also called support part 16) made of a rectangular film like heat-resistant resin (e.g., epoxy-based resin) that does not melt under a temperature of thermocompression bonding during implementation. The region is formed along a width that is substantially same as the width along the right and left direction of the exterior body 11.

(24) Manufacturing Method

(25) The following gives a description of the method of manufacturing the power storage element 1a. FIGS. 7A to 7D illustrate this manufacturing method where the manufacturing procedures are shown. As illustrated in FIG. 7A, an insulating paste-form heat-resistant resin (e.g., epoxy resin) is applied by screen printing or the like to the surface of the release sheet 16a having a contour similar to the support part and formed of such as fluorinated resin. Then as illustrated in FIG. 7B, the release sheet 16a is disposed to the back face 51 sides of the electrode terminal plates (23, 33) of the power storage element body 1 in a manner having the application face of the heat-resistant resin 16b face the back face 51 sides. Here, the release sheet 16a is positioned to accord with the region where the support part 16 is to be formed and the back faces 51 of the electrode terminal plates (23, 33) are tightly adhered to the face where the heat-resistant resin 16b is applied, as illustrated in FIG. 7C. In this example, the back faces 51 of the electrode terminal plates (23, 33) is pushed against the face where the heat-resistant resin 16b is applied so that the surface layer portions of the back faces 51 of these electrode terminal plates (23, 33) are buried in the paste-form heat-resistant resin 16b. Then the heat-resistant resin in this state is thermally cured or melted and hardened by the thermoplastic characteristics, and thereafter the release sheet 16a is separated from the support part 16 that is made of heat-resistant resin formed in a film shape, as illustrated in FIG. 7D. Hereby, the power storage element 1a shown in FIG. 5 is completed.

(26) The power storage element according to the present working example includes a support part made of insulating heat-resistant resin in this way. During the thermocompression bonding process, heat is transferred to the electrode terminal plates and the ACF layered to the lower surfaces thereof through this support part. For such reason, the temperatures of the electrode terminal plates do not rise rapidly so that damages to the electrode body inside the exterior body can be averted and an external short-circuit which had been issues in the conventional support-type laminate-type power storage element can be kept from being generated in principle.

(27) =External Short Circuit=

(28) As mentioned above, in addition to the effect similar to a support-type laminate-type power storage element such that damages to the electrode body during thermocompression bonding is averted, the power storage element according to the working example achieves an effect that an external short-circuit which had been issues in the support-type laminate-type power storage element would not be generated. Therefore, in order to confirm that an external short-circuit caused by thermocompression bonding would not be generated to the power storage element according to the present working example, the power storage element according to the present working example (hereinafter, working example) and a conventional support-type laminate-type power storage element (hereinafter, comparative example) were assigned as samples and many of the respective samples were manufactured. The samples of the comparative example are support-type laminated lithium primary batteries (for example, CF052039(N) manufactured by FDK CORPORATION), which is disclosed as the product in the aforementioned Non-Patent Literature 1. And the samples of the working examples only differ to have formed a support part instead of a support tab and the configuration as a power storage element is completely the same as the comparative example. All the individual bodies were implemented on the circuit board under the same conditions (e.g., jig temperature of 170 C., pressure of 3 MPa and time of 8 secs.) The ACF 70 and the circuit board 60 are layered in this order to the electrode terminal plates (23, 33) from below and a heater incorporating jig 80 only need to be used to thermocompression bond from above the support part 16 when the power storage element 1a of the working example is implemented to the circuit board 60, as illustrated in FIG. 8. Then the voltages between the positive and negative electrodes were measured before and after implementation to confirm any existence of a voltage drop. 42% of the individual bodies of the samples of the comparative example showed some voltage drop whereas none of the samples of the working example showed a voltage drop.

(29) Implementation Reliability

(30) As described above, the power storage element according to the present example is implemented to the circuit board by thermocompression bonding via the support part made of insulating heat-resistant resin. Hereby, an external short-circuit can be certainly kept from being generated. However, even when an external short-circuit is not generated, if the implementation reliability, that is, the adhering strength between the circuit board and the electrode terminal plates were to decline, issues during actual use would arise. Therefore, the implementation reliability of the power storage elements according to the present working example was examined. Specifically, adhering strength tests were conducted on all of the individual manufactured samples of the working example and the samples of the comparative example in implemented states. A tensile tester was used for the adhering strength tests where the support part and the support tab were pulled in the separating direction with the circuit board fixed. The adhering strength (N) was measured when the electrode terminal plate separated from the circuit board. Results showed that the adhering strengths of the samples of the comparative example were within the range of 2N to 6N whereas the adhering strengths of the samples of the working example increased dramatically to be within the range of 8N to 16N. The reason for this is understood to be because the comparative example is thermocompression bonded from the top surface of the support tab being the laminate film itself that is substantially soft and whose surface is not so flat whereas the working example is thermocompression bonded from the top surface of the support part that is in a hardened state and very flat and is more rigid than the support tab. In other words, it is understood that the power storage element according to the working example is thermocompression bonded from above the support part that is very flat in a hardened state so that the heat of the jig is evenly transferred to the electrode terminal plates and into the face of the ACF that is positioned therebelow thereby improving the adhering strength. In this way, the power storage element according to the working example not only has an external short-circuit kept from being generated by the thermocompression bonding process but has the implementation reliability improved.

Other Working Examples

(31) Both the thermoset resin and thermoplastic resin can be used as the resin material that configures the support part. Generally, thermoset resin has a better heat resistance property, however, thermoplastic resin may be used as long as the material does not melt during thermocompression bonding. Further, appropriate material such as epoxy resin, polyimide resin, acrylic resin, urethane resin, synthetic rubber resin, silicon resin can be adopted according to the specification or performance required to the power storage element. The laminate-type power storage element, for example, houses a power generating element in the exterior body having a structure formed by welding the peripheral edge regions of the opposing laminate films by thermocompression bonding. And this laminate-type power storage element had issues of having moisture easily entering in from the margin where the electrode terminal plates are guided outside. Therefore, the use of resin (e.g., epoxy resin) having a characteristic that does not allow moisture to pass through (moisture barrier property) into the support part is expected to solve the issues of the laminate-type power storage element having moisture passing through. In other words, the region, in the margins of the exterior body, where the electrode terminal plates are guided out is covered by resin material having a moisture barrier property when the support part is formed, hereby blocking the path to keep the moisture from entering therein.

(32) The inner structure of the power storage element according to the working example of the present invention may have the configuration and the structure different from the ones illustrated in FIG. 1B that has been illustrated as a schematic diagram. For example, the electrode terminal plate may be configured of only a terminal lead. Alternatively, a strip-shaped region projecting from a region over which the electrode material is applied may be formed integrally with an electrode current collector to guide a distal end of the strip-shaped region to the outside of the exterior body. That is, the electrode current collector itself, which is referred to as the core, may also serve as the electrode terminal plate. Obviously, as long as the present invention has the structure that seals the flat plate-shaped electrode body with the laminated structure in the exterior body formed of the laminated films, the present invention is applicable to various kinds of laminate-type power storage elements (for example, a lithium secondary battery and an electric double layer capacitor) not limited to the lithium primary battery.