JP5115204B2 - Surface mount square storage cell - Google Patents

Description

  The present invention relates to a surface-mounting rectangular storage cell having a rectangular external shape, particularly in pursuit of mounting area efficiency, among surface-mounting storage cells used in various electronic devices.

  FIGS. 11A and 11B are a front sectional view and a plan view showing the structure of this type of conventional surface-mounting storage cell. In FIG. 11, reference numeral 40 denotes a coin shape such as a secondary battery or a capacitor. A storage cell 49 is a storage cell, in which a pair of positive / negative polarizable electrodes 41a and 41b are arranged so as to face each other via an insulating separator 42, and impregnated with a driving electrolyte solution (not shown). The upper lid metal case 44 and the lower lid metal case 45 connected via the current collectors 43 formed on both sides are sealed by mechanical caulking or drawing through an insulating gasket 46. Solder plating portions 47a and 48a are formed at the tip of the negative terminal plate 48 connected to the negative electrode of the coin-type storage cell 40 and the positive terminal plate 47 connected to the positive electrode.

  Conventionally, along with the downsizing of devices, etc., surface mounting of electronic components on the substrate of primary batteries and capacitors used for backup of auxiliary power supplies and memories has progressed, and as a method for mounting surface-mounting storage cells Surface mounting by reflow soldering has become mainstream.

In response to such a demand, the structure in which the upper lid metal case 44 and the lower lid metal case 45 are sealed by mechanical caulking or drawing through an insulating gasket 46 is mechanically uniformly sealed on the circumference. Since performance is obtained, it is mass-produced as a surface-mounting storage cell that can be surface-mounted by reflow soldering in a board-mounted form in a coin shape that is circular (see, for example, Patent Documents 1 and 2).
JP 2002-170551 A JP 08-298232 A

  However, in recent years, further miniaturization of portable devices such as mobile phones has progressed, electronic parts have become more highly integrated, and even in primary batteries and capacitors for surface mounting used for backup of auxiliary power supplies and memories. Further downsizing is required.

  In addition, in surface mounting technology for electronic components on boards, lead-free soldering materials that eliminate lead, which is a hazardous substance, have been developed to reduce environmentally hazardous substances in consideration of recent environmental problems. Therefore, there is a demand for a surface mount power storage cell that has a high reflow heat resistance temperature and a high heat resistance performance and is small in size.

  In the above-described conventional surface-mounting coin-shaped storage cell, since the storage cell such as a secondary battery or a capacitor is circular, the square floor area that occupies the substrate as the storage cell component when mounted on the substrate is theoretically In addition to a 22% loss (theoretical value that does not consider the coverage of the exterior material), the negative electrode terminal plate 48 and the positive electrode terminal plate 47 connected to the coin-shaped storage cell 40 protrude in the outer peripheral direction of the storage cell 40. Since this configuration requires a mounting area corresponding to the floor area of the terminal board protruding from the outer peripheral portion in addition to the square floor area that occupies the substrate of the storage cell 40, the product in the actual coin-type storage cell The current situation is that a board mounting area loss of about 40% occurs at a diameter of 6 mm.

  Under these circumstances, when used in devices that require further downsizing in recent years, such as mobile devices represented by mobile phones, there is a demand for a smaller size and larger capacity required for coin-shaped storage cells. There was a problem that it was difficult to cope with.

  In order to solve these problems, the storage cell has a rectangular shape, and the positive / negative electrode terminal plate is provided in the outer shape of the storage cell, so that the area occupied by the substrate is approximately 40% higher than that of the circular storage cell, and the size is reduced. Is considered possible.

  However, on the other hand, when the rectangular shape is used, the sealing structure in which the upper and lower metal cases constituting the energy storage cell are caulked and squeezed via an insulating gasket cannot be uniformly sealed at the corner portion, so that when mounting the board There was a problem that the internal electrolyte leaked due to thermal stress caused by reflow soldering.

  In addition, it is conceivable to use a resin-molded structure in which square-shaped energy storage cells are directly resin-molded without using a metal case. There were problems in reliability such as cracks in the resin and leakage of the electrolyte.

  In order to improve the mounting area loss, which is a problem of the prior art, the present invention achieves a performance that satisfies the reflow performance when mounted on a board by reducing the size with a rectangular storage cell. An object of the present invention is to provide a surface-mounting rectangular storage cell that contributes to downsizing of devices and the like.

In order to solve the above-described problems, the present invention includes a power storage element in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween, a pair of rectangular metal cases that are arranged facing each other and store the power storage element, and a cross section A substantially H-shaped rectangular frame-shaped insulating gasket, an exterior resin covering the pair of metal cases, and a positive terminal plate and a negative electrode which are joined to the pair of metal cases and exposed at least partially on the outer surface. A pair of metal cases, the pair of metal cases are bent stepwise from the bottom and provided with flanges at the open ends, and the flanges are disposed in upper and lower recesses of the insulating gasket, The resin is configured to seal between the flange portion and the connecting portion of the insulating gasket by pressing the pair of metal cases .

As described above, according to the present invention , the storage cell can be miniaturized by making the storage cell into a square shape, and the mounting area can be reduced, and the pair of rectangular metal cases and the flanges at the open ends of the pair of metal cases are insulated. By placing it in the recesses on the upper and lower surfaces of the conductive gasket and covering it with exterior resin, it can be sealed without mechanical caulking or drawing, and it can withstand lead-free reflow soldering when mounted on a board. A surface-mounting rectangular storage cell having heat resistance can be provided.

An embodiment of the present invention includes a rectangular power storage element in which a polarizable electrode serving as a positive electrode and a polarizable electrode serving as a negative electrode are stacked with a separator interposed therebetween, and a pair of the power storage elements that are arranged facing each other vertically. A rectangular metal case, a rectangular frame-like insulating gasket that is incorporated and sealed in the open ends of the pair of metal cases, and a positive / negative terminal plate joined to the pair of metal cases, respectively. In the surface-mounting rectangular storage cell, the insulating gasket has a substantially H-shaped cross section having recesses into which the open ends of the pair of metal cases are fitted on the upper and lower surfaces, and a part of the positive / negative terminal plate is a connecting terminal for mounting. The exterior resin is applied to the entire surface so as to be exposed on the outer surface.

  The rectangular electricity storage element is enclosed in the rectangular metal case and the exterior resin is applied to the whole. The mounting area of the electricity storage cell is higher than that of the conventional coin-shaped circular electricity storage cell. The structure can be greatly reduced in size, and is a configuration in which the open ends of a pair of metal cases are fitted into the recesses having a substantially H-shaped cross section of the insulating gasket and sealed to provide exterior resin. In the caulking joint used as a general sealing method of a certain coin shape, the mechanical caulking process of each square corner part is difficult, and the problem of being unable to seal uniformly at the corner part, The problem can be solved all at once by fitting and sealing the open end.

Further, in addition to the above configuration, the insulating gasket is formed of a thermoplastic resin having a heat resistant temperature higher than the molding temperature of the exterior resin.

  In the above-mentioned insulating gasket, if molding is performed with an exterior resin having a molding temperature higher than the heat resistance temperature of the insulating gasket, the insulating gasket may be thermally deteriorated at the temperature at which the exterior resin is formed. It may be missing. In order to solve this problem, by selecting a resin material for an insulating gasket having a heat resistance higher than the molding temperature of the exterior resin, this problem can be solved and the reliability of the sealing performance can be ensured.

Further, in addition to the above-described configuration, at least one of the positive / negative terminal plates of the terminal plate is bent in a stepped manner in a direction away from the metal case except for the connection portion with the metal case, thereby providing a stepped portion. Is.

  In a state where a part of the stepped portion is exposed on the outer surface, a positive / negative terminal plate can be easily formed on the lower surface portion of the exterior resin by covering the storage cell with the exterior resin in a square shape, Moreover, since the crack of the exterior resin near the terminal board is reduced and the metal case is covered with the exterior resin, reliable sealing can be performed.

Further, in addition to the above configuration, the height of the outer peripheral wall portion of the insulating gasket is configured to be higher than the height of the inner peripheral wall portion.

Along with downsizing, surface mounting power storage cells are indispensable requirements to have a flat structure with a low product height when mounted. For this purpose, the inner surface of the metal case is engaged with the inner peripheral wall portion of the insulating gasket and the height of the inner peripheral wall portion and the outer peripheral wall portion of the concave portion of the insulating gasket is important. In order to reduce the height of the surface-mounting rectangular storage cell, the inner peripheral wall portion of the insulating gasket is lowered, and the height of the outer peripheral wall portion is made higher than the height of the inner peripheral wall portion, so that the open end of the metal case The surface area of the flat wall surface storage cell can be realized by increasing the surface area of the outer peripheral wall portion facing each other and with more reliable sealing.

Further, in addition to the above-described configuration, the open ends of the pair of metal cases are fitted into the substantially H-shaped upper and lower recesses of the gasket, respectively, and are thermally sealed and sealed. The sealing performance can be further improved by applying heat to the insulating gasket 16 and thermally sealing it with the metal case before forming the exterior resin.

Further, in addition to the above-described configuration, the surface of the pair of metal cases is subjected to a roughening process for improving adhesion with the exterior resin. By roughening the surface of the pair of metal cases, the adhesion with the exterior resin can be increased by the anchor effect, and more reliable sealing can be performed.

Further, in addition to the above-described configuration, the surface of the positive / negative terminal plate is subjected to a roughening process for improving adhesion with the exterior resin. By roughening the surface of the positive / negative terminal board, the adhesion with the exterior resin can be increased by the anchor effect, and more reliable sealing can be performed.

In addition to the above-described configuration, the power storage element is configured such that a polarizable electrode made of a metal oxide or a hydrate of metal oxide and a conductive polymer faces each other through a polymer electrolyte membrane. Therefore, a storage cell having a higher voltage, higher capacity, and higher energy density than the storage element can be realized.

In addition to the above structure, the power storage element has a multilayer structure. When the power storage elements have a multilayer structure, the power storage elements can be connected in series, and a power storage cell with higher voltage and higher energy density can be realized.

(Embodiment 1)
The following describes a first embodiment of the present invention.

  FIG. 1 is a cross-sectional view showing the configuration of a surface-mounting rectangular storage cell according to Embodiment 1 of the present invention, and FIGS. 2A to 2C are metal cases used for the surface-mounting rectangular storage cell. FIG. 3A to FIG. 3C are a plan view, a front cross-sectional view, and a main part showing an insulating gasket used in the rectangular storage cell for the same surface mounting. It is an expanded sectional view of a part.

  In FIG. 1, reference numeral 10 denotes a storage cell, and a storage element 20 constituting the main part of the storage cell 10 has a pair of positive / negative polarizable electrodes 11 a and 11 b formed in a square shape. It is configured in a rectangular shape by being arranged so as to face each other via the insulating separator 12. A current collector 13 made of a carbon layer is formed on both surfaces of the electricity storage element 20.

Further, the insulating gasket 16 is formed in a rectangular frame shape from a thermoplastic resin as shown in FIGS. 3A to 3C, and FIG. ) (A-a ′ portion) has a substantially H shape, in which the outer peripheral wall portion 16b and the inner peripheral wall portion 16c are connected by a connecting portion 16d, and concave portions 16a are formed above and below the connecting portion 16d. In a state where the storage element 20 is impregnated with a driving electrolyte solution (not shown), a bowl-like shape provided in an opening of an upper metal case 14 formed in a square shape as shown in FIGS. The open end 14a is fitted into and held in a substantially H-shaped upper concave portion 16a of the insulating gasket 16, and the hook-shaped open end 15a provided in the opening of the lower metal case 15 is similarly used as the metal case. 14 is fitted into the lower recess 16a of the insulating gasket 16 so as to be engaged and held.

  In addition, plate-like positive / negative terminal plates 17 and 18 are connected to the outer surfaces of the pair of metal cases 14 and 15 by laser welding, respectively, and in directions opposite to each other along the surfaces of the metal cases 14 and 15. After being pulled out and covered with the exterior resin 19, the positive / negative electrode terminal plates 17 and 18 are bent in the same direction along the side surfaces of the exterior resin 19, and the positive / negative electrode terminal plates 17 and 18 are formed on the bottom surface of the exterior resin 19. The plating processing portions 17a and 18a, which have been subjected to plating processing, are configured to be exposed on the outer surface. The positive / negative terminal plates 17 and 18 and the metal cases 14 and 15 may be connected by mechanical caulking, ultrasonic welding, or spot resistance welding.

  The pair of polarizable electrodes 11a and 11b are prepared by mixing activated carbon powder, carbon black as a conductivity-imparting agent, polytetrafluoroethylene as a binder, and kneading thoroughly with a kneader to produce a paste. It is formed by molding into a square of the size of and then drying it.

  The metal cases 14 and 15 are made of the same shape and the same size using a stainless steel plate.

  In addition, a thermoplastic resin is suitable for the insulating gasket 16, and in the first embodiment, glass fiber-containing polyphenylene sulfide (PPS) is used.

  Further, a thermosetting resin is suitable as the exterior resin 19, and an epoxy resin is used in the first embodiment. When covering with the exterior resin 19, the metal cases 14 and 15 and the positive / negative electrode terminal plates 17 and 18 as the storage cell 10 arranged in an injection mold (not shown) are respectively connected by slide pins (not shown). Molding is performed while maintaining pressure contact.

  In addition to the thermosetting resin, a thermoplastic resin can be used as the exterior resin 19.

In the first embodiment , the insulating gasket 16 is formed of a thermoplastic resin having a heat resistance higher than the molding temperature of the exterior resin 19.

  When the insulating gasket 16 is molded with the exterior resin 19 having a molding temperature higher than the heat resistance temperature of the insulating gasket 16, the insulating gasket 16 is thermally deteriorated at the temperature at which the exterior resin 19 is formed, and the sealing performance is reliable. May lack sexuality. In order to solve this problem, by selecting the resin material of the insulating gasket 16 having a heat resistance higher than the molding temperature of the exterior resin 19, this problem can be solved and the reliability of the sealing performance can be ensured.

  For example, when the exterior resin 19 is an epoxy resin that is a thermosetting resin, the molding temperature of the epoxy resin is about 150 ° C. to 200 ° C., and the resin of the insulating gasket 16 is heat resistant 280. In addition to polyphenylene sulfide (PPS) with glass fiber having a temperature of ℃ or higher, mixed resin of PPS and butyl rubber with glass fiber, liquid crystal polymer (LCP) having a heat resistance level of 270 ° C, polyether ether ketone (PEEK) having a heat resistance of 300 ° C Material) is suitable. Further, when the exterior resin 19 is a liquid crystal polymer (LCP) which is a thermoplastic resin, the heat resistance temperature of the liquid crystal polymer is about 270 ° C., and the resin of the insulating gasket 16 has a heat resistance of 280 ° C. or more. Suitable examples include glass fiber-containing polyphenylene sulfide (PPS) and polyether ether ketone (PEEK material) having a heat resistance of 300 ° C. If elasticity is required for the material of the insulating gasket 16, butyl rubber is suitable. More preferably, butyl rubber is obtained by adding carbon black and silica as reinforcing agents to non-halogen butyl rubber and vulcanizing the resin with an alkylphenol resin.

In the first embodiment , at least one of the positive / negative electrode terminal plates 17 and 18 is bent in a stepped manner in a direction away from the metal cases 14 and 15 except for the connection portions of the metal cases 14 and 15 to form the stepped portion. The configuration is provided.

Figure 4 is a cross-sectional view showing the structure of a surface mounting rectangular storage cells are examples. The basic configuration is the same as that of FIG. 1 shown in the first embodiment, and only different parts will be described. In FIG. 4, a positive electrode terminal plate 17 and a negative electrode terminal plate 18 are joined to the outer surfaces of the pair of metal cases 14 and 15, respectively, and the direction apart from the metal case 15 except for the joint portion of the negative electrode terminal plate 18 with the metal case 15. A stepped portion 18b is provided by being bent stepwise, and a portion of the stepped portion 18b and a portion of the positive electrode terminal plate 17 are covered with an exterior resin 19 so as to be exposed on the outer surface. As a result, the surface-mounted rectangular storage cell 10 is configured.

  The reactance due to the length of the negative electrode terminal plate 18 is minimized by covering the negative electrode terminal plate 18 in a square shape with the outer resin 19 in a state where a part of the stepped portion 18b is exposed on the outer surface of the outer resin 19. In addition, at the bottom of the exterior resin 19, a reliable sealing structure without cracking of the exterior resin 19 is obtained at the terminal lead-out portion from the exterior resin 19, and the negative electrode terminal plate 18 can be easily formed. That is, in the structure of FIG. 1 which is the embodiment, in order to reduce reactance, which is one of important electrical characteristics of the storage cell 10, it is necessary to shorten the length of the negative electrode terminal plate 18, By pulling out the plate 18 from the bottom of the exterior resin 19, the length of the negative electrode terminal plate 18 can be shortened and the reactance can be reduced.

  However, the space between the bottom portion of the exterior resin 19 on the side from which the positive / negative electrode terminal plates 17 and 18 are drawn out and the power storage element 20 is constituted by a thin portion for miniaturization, and the mechanical strength is low. Therefore, there has been a problem that a resin crack occurs at the boundary portion where the negative electrode terminal plate 18 is exposed from the bottom of the exterior resin 19 by applying mechanical stress to bend the terminal plate. However, by bending the negative terminal plate 18 in a stepped manner in advance and providing the stepped portion 18b, it is not necessary to bend the negative terminal plate 18 after the exterior resin 19 is provided, and the exterior resin 19 is reliably subjected to no mechanical stress. Sealing can be performed and the reactance of the negative electrode terminal plate 18 is minimized.

  Further, in the structure in which the positive electrode terminal plate 17 having a structure in which the storage element 20 is turned upside down is arranged below the storage cell 10, the configuration in which the stepped portion is provided by bending the positive terminal plate 17 in the above-mentioned step shape has the same effect. can get.

In the first embodiment , the insulating gasket 16 is configured such that the height of the outer peripheral wall portion 16b of the insulating gasket 16 is higher than the height of the inner peripheral wall portion 16c.

  FIG. 5 is a cross-sectional view showing the configuration of the surface-mounting rectangular storage cell in the configuration. FIGS. 6A to 6C are a plan view, a front sectional view, and an enlarged sectional view showing a main part of a metal case used in the rectangular storage cell for mounting on the same surface. FIGS. 7A to 7C are a plan view, a front sectional view, and an enlarged sectional view showing a principal part of an insulating gasket used for the rectangular storage cell 16 for mounting on the same surface. The basic configuration is the same as that of FIG. 1 shown in the first embodiment, and only different parts will be described. In FIG. 5, in the structure in which the open ends 14a and 15a of the pair of metal cases 14 and 15 are fitted and held in the recesses 16a having a substantially H-shaped cross section of the insulating gasket 16 and covered with the exterior resin 19, the insulation shown in FIG. The gasket 16 is joined to the inner surface of the recess 16a of the outer peripheral wall 16b in the substantially H-shaped cross section at the open ends of the metal cases 14 and 15 and sealed with the exterior resin 19. By making the height h2 of the outer peripheral wall portion 16b of the insulating gasket 16 higher than the height h1 of the inner peripheral wall portion 16c, the surface area facing the open ends 14a, 15a of the metal cases 14, 15 is increased, and the exterior resin Thus, a low profile product can be realized in which reliable sealing is performed and the product height during surface mounting is kept low.

  That is, in FIG. 6, the pair of metal cases 14 and 15 are usually made of an aluminum flat plate or a stainless flat plate, and the flat plate is formed by drawing or impact processing. However, after drawing or impact processing, in order to prevent cracks and cracks in the phase portions 14b and 15b of the metal cases 14 and 15, the angle (θ) and punching when the metal cases 14 and 15 are extracted from the mold The metal molds 14 and 15 are designed with a radius of curvature (R) at the edge portion, and the machined metal cases 14 and 15 are opened at the open end 14a according to the extraction angle (θ) or the curvature (R) at the phase portions 14b and 15b. , 15a has an inclination. When the open ends 14a and 15a of the metal cases 14 and 15 are fitted into the upper and lower recesses 16a of the insulating gasket 16 by the inclination due to the drawing angle and curvature, the metal cases 14 and 15 are edge portions of the inner peripheral wall portion 16c of the insulating gasket 16. Since it contacts at the time of engagement in 16f, the height dimension of the inner peripheral wall part 16c becomes an important element.

  On the other hand, for portable devices such as mobile phones, a flat structure in which the product height is lowered when mounted along with downsizing is an indispensable requirement, and the height of the inner peripheral wall portion 16c of the insulating gasket 16 cannot be increased. It had the problem that.

Therefore , by increasing the height h2 of the outer peripheral wall portion 16b of the insulating gasket 16 to be higher than the height h1 of the inner peripheral wall portion 16c, the facing area with the metal cases 14 and 15 is increased and the sealing performance is maintained. Even when the metal cases 14 and 15 are actually processed, even when the open ends 14a and 15a are inclined, it is possible to reduce the height of the surface-mounted rectangular storage cell.

Alternatively , the open ends of the pair of metal cases 14 and 15 may be fitted into the substantially H-shaped upper and lower recesses 16a of the insulating gasket 16 and thermally sealed to be sealed. FIG. 8 is a cross-sectional view of a surface-mounting rectangular storage cell showing the configuration. The basic configuration is the same as that of FIG. 1 shown in the first embodiment, and only different parts will be described. In FIG. 8, in the case where a thermoplastic resin is used for the insulating gasket 16, the temperature exceeding the heat-resistant temperature is applied to the insulating gasket 16 before the outer resin 19 is formed. In addition to the end face of the metal cases 14 and 15 from the outside of the wall portion 16b, the heat welded portion 16m with the metal cases 14 and 15 is formed by heat pressure welding around the entire rectangular frame of the metal cases 14 and 15. The sealing performance can be further improved by forming and sealing. When polyphenylene sulfide (PPS) is used for the insulating gasket 16, the sealing performance can be improved by heat welding at a temperature of about 300 ° C. exceeding the heat resistance temperature.

Alternatively , the surface of the pair of metal cases 14 and 15 may be roughened to improve the adhesion with the exterior resin 19. The pair of metal cases 14 and 15 are made of stainless steel. However, by roughening the outer surfaces of the metal cases 14 and 15, the adhesion with the exterior resin 19 is increased due to the anchor effect, and more reliable. Sealing can be performed. The roughening processing of the metal cases 14 and 15 can be performed by roughening by sandblasting, dull processing, or satin processing.

Further , the surface of the positive / negative electrode terminal plates 17 and 18 may be subjected to a roughening process for improving the adhesion with the exterior resin 19, and the surfaces of the positive / negative electrode terminal plates 17 and 18 may be roughened. By doing so, adhesiveness with exterior resin 19 can be increased by an anchor effect, and more reliable sealing can be performed.

  The positive / negative electrode terminal plates 17 and 18 are made of an aluminum material or a stainless material, and have a surface roughness (Ra) of 0. 0 for the purpose of improving the adhesion to the exterior resin 19. The surface is roughened to a thickness of 05 μm or more, and tin-plated portions 17a and 18a are applied to portions that are mounted on a substrate (not shown) and soldered.

As described above, the surface-mounting rectangular storage cell according to the embodiment of the present invention reduces the mounting area loss by forming the storage cell 10 including the storage element 20 in a square shape, and the metal cases 14 and 15. In the caulking coupling used as a general coupling method, the open ends 14a, 15a of the open ends of the two are engaged and held by an insulating gasket 16 having a substantially H-shaped cross section and covered with an exterior resin 19. It is possible to solve the problem that it is difficult to caulk each corner of the square at once, with a high level of reliability including sealing that satisfies the heat resistance during reflow soldering when mounting on the board, There is also a special effect that can be guaranteed.

(Embodiment 2)
The following describes a second embodiment of the present invention.

  FIG. 9 is a cross-sectional view showing the configuration of another surface-mounting rectangular storage cell. The power storage element 20 has a configuration in which a polarizable electrode made of a metal oxide or a hydrate of metal oxide and a conductive polymer faces each other through a polymer electrolyte membrane. The storage cell 10 having high voltage and high energy density can be realized with voltage. The basic configuration is the same as that shown in FIG. 1, and only different parts will be described.

  In FIG. 9, the electricity storage element 20 constituting the electricity storage cell 10 is configured such that polarizable electrodes 31 a and 31 b made of a metal oxide and a conductive polymer face each other through a polymer electrolyte membrane 32. .

  The polarizable electrodes 31a and 31b made of the metal oxide and the conductive polymer are used as the current collector 13 after the metal oxide particles and the conductive polymer are dispersed or dissolved in a volatile solvent to form a paste. It can produce by apply | coating and drying to metal foil.

Examples of the metal oxide include RuO ₂ , CoO ₂ , Co ₃ O ₄ , MnO ₂ , NiO, PbO ₂ , WO ₃ or RuO ₂ and IrO ₂ , TiO ₂ , ZrO ₂ , V ₂ O ₅ , Nb ₂ O ₅ . A composite with at least one kind can be mentioned. The metal oxide may be a hydrate of metal oxide, and the metal oxide particles are preferably 0.01 to 5 μm.

  The conductive polymer is composed of a conductive polymer such as polyaniline, polypyrrole or polythiophene, or a proton conductive polymer having an ionic group such as a sulfonic acid group, a sulfonimide group or a carboxylic acid group. Things.

  The polymer electrolyte membrane 32 is a membrane obtained by mixing PTFE (polytetrafluoroethylene) fiber with a fluorinated cation exchange resin having a sulfonic acid group or a carboxylic acid group, and has a functional group on the porous film. A film obtained by impregnating a solution of a fluoropolymer having the above, a commercially available Nafion (registered trademark), Aciplex (registered trademark), Flemion (registered trademark), or the like can be used.

  The metal foil used as the current collector 13 can be a foil made of stainless steel, aluminum, titanium, or the like.

  As described above, the surface-mounting rectangular electricity storage cell according to the present embodiment has the electricity storage element 20 connected to the polarizable electrodes 31a and 31b made of a metal oxide or a hydrate of metal oxide and a conductive polymer through the polymer electrolyte membrane 32. Is arranged so as to face each other, and a structure in which the layers are stacked is used, whereby a high energy density can be obtained at a high voltage.

  In addition, since the storage cell 10 is housed in the metal cases 14 and 15 and this is covered with the exterior resin 19 so that the metal cases 14 and 15 can be held by the exterior resin 19, the sealing ability is further improved and the impedance is reduced. Therefore, even if lead-free soldering is performed, the thermal stress of reflow soldering to the power storage element 20 can be suppressed, and a special effect that a long life can be achieved is obtained.

  In addition, FIG. 10 is sectional drawing which showed the structure of the square electrical storage cell for surface mounting which is another Example of this invention. The basic configuration is the same as the configuration based on FIG. 9, and only different parts will be described. In FIG. 10, the power storage element 20 has a multilayer structure. By making the electricity storage element 20 have a multilayer structure, the electricity storage elements 20 can be connected in series, and the electricity storage cell 10 with higher voltage and higher energy density can be realized. In addition, a power storage element in which the polarizable electrodes 31a and 31b made of a metal oxide and a conductive polymer face each other with the polymer electrolyte membrane 32 facing each other, and is stacked in three to six stages is a pair of metal cases. By compressing and storing at 14 and 15, impedance characteristics can be further reduced.

  In the following two types of surface-mounting rectangular storage cells of Example 1 and Example 2 based on the first embodiment and the following two types of surface-mounting rectangular storage cells of Example 3 and Example 4 based on the second embodiment Then, reflow soldering (peak temperature 260 ° C 40sec) surface mounting on the printed circuit board using lead-free solder, its capacity change and leakage test results, moisture resistance load test (40 ° C 60% RH 2.6V load 1000) The results of the capacity change after (time) are shown in (Table 1). As a comparative example, the surface-mounting rectangular electric double layer capacitor shown in FIG. 11 was used. The number of samples is 50, and the capacity change rate is the capacity change rate before and after reflow.

Example 1
The insulating gasket shown in FIG. 5 is made of glass-filled PPS, and the cathode terminal plate is provided with a stepped portion bent into a staircase. The height of the outer peripheral wall of the insulating gasket is higher than the height of the inner peripheral wall, A surface-mounting rectangular storage cell in which the surface of the positive / negative electrode terminal plate is roughened is referred to as Example 1.

(Example 2)
In the surface-mounting rectangular storage cell shown in FIG. 8, the substantially H-shaped concave portion of the insulating gasket and the open end of the metal case were heat-welded in the surface-mounting rectangular storage cell shown in FIG. 5 of Example 1 above. A surface-mounting rectangular storage cell is referred to as Example 2.

(Example 3)
A surface-mounting rectangular electricity storage cell configured to use the polymer electrolyte membrane shown in FIG. 9 as a separator and face the polarizable electrode is referred to as Example 3.

Example 4
In Example 3 shown in FIG. 9 described above, Example 4 is a surface-mounting rectangular storage cell in which a substantially H-shaped recess of an insulating gasket and an open end of a metal case are heat-welded.

(Comparative example)
As a comparative example, a square electric double layer capacitor for surface mounting, which has the same caulking structure as the coin type as shown in FIG. 11 and is sealed using a rectangular stainless steel case as a metal case.

（表１）から明らかなように、本発明の実施例１〜４の面実装用方形蓄電セルは比較例に比べて、リフロー後の容量変化率が小さく、液漏れも無いことから、鉛フリーのリフロー温度に耐えることができる。また、耐湿負荷試験においても、比較例と比べて容量変化率が小さいことから信頼性の高い面実装用方形蓄電セルを提供することができる。

As is clear from (Table 1), the surface-mounted rectangular energy storage cells of Examples 1 to 4 of the present invention have a smaller capacity change rate after reflowing and no liquid leakage compared to the comparative example, and thus lead-free. Can withstand reflow temperatures of Also, in the moisture resistance load test, since the capacity change rate is smaller than that in the comparative example, a highly reliable surface-mounting rectangular storage cell can be provided.

  In the present embodiment, the electric double layer capacitor has been described as an example of the electric storage cell 10, but the present invention is not limited to this, and may be an electric storage cell such as a secondary battery, Similar effects can be obtained.

  The surface-mounting rectangular storage cell according to the present invention has the effect of reducing the mounting area and reducing the size and increasing the capacity and realizing high reliability. In particular, miniaturization and high-density mounting are required. It is useful as a field for portable devices.

Sectional drawing which showed the structure of the surface-mounted square electrical storage cell by Embodiment 1 of this invention (A) The top view which shows the metal case used for the square electrical storage cell for same surface mounting, (b) The same front sectional view, (c) The principal part expanded sectional view (A) Top view which shows the insulating gasket used for the square electrical storage cell for same surface mounting, (b) Front sectional drawing, (c) Main part expanded sectional view Sectional drawing which showed the structure of the square electrical storage cell for surface mounting of the other Example by Embodiment 1 of this invention Sectional drawing which showed the structure of the square electrical storage cell for surface mounting of the other Example by Embodiment 1 of this invention (A) The top view which shows the metal case used for the square electrical storage cell for same surface mounting, (b) The same front sectional view, (c) The principal part expanded sectional view (A) Top view which shows the insulating gasket used for the square electrical storage cell for same surface mounting, (b) Front sectional drawing, (c) Main part expanded sectional view Sectional drawing which showed the structure of the square electrical storage cell for surface mounting of the other Example by Embodiment 1 of this invention Sectional drawing which showed the structure of the surface-mounted square electrical storage cell of the Example by Embodiment 2 of this invention The front view which showed the structure of the square-shaped electrical storage cell for surface mounting of the other Example by Embodiment 2 of this invention (A) Front sectional view showing the configuration of a conventional coin-type storage cell for surface mounting, (b) The same plan view

DESCRIPTION OF SYMBOLS 10 Storage cell 11a, 11b Polarized electrode 12 Separator 13 Current collector 14,15 Metal case 16 Insulating gasket 17 Positive electrode terminal plate 17a Tin plating process part 18 Negative electrode terminal board 18a Tin plating process part 18b Negative side step part 19 Exterior Resin 20 storage element

Claims (8)

A storage element in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween, a pair of rectangular metal cases that are arranged to face each other and store the storage element, and a rectangular frame-shaped insulating gasket having a substantially H-shaped cross section And an exterior resin that covers the pair of metal cases, and a positive terminal plate and a negative terminal plate that are bonded to the pair of metal cases and exposed at least partially on the outer surface,
The pair of metal cases are bent stepwise from the bottom and provided with flanges at the open ends, the flanges are disposed in the upper and lower recesses of the insulating gasket, and the exterior resin covers the pair of metal cases. A surface-mounting rectangular electricity storage cell that seals between the connecting portion of the flange portion and the insulating gasket by pressing . The surface-mounting rectangular storage cell according to claim 1, wherein a gap is provided between an inner peripheral wall portion of the insulating gasket and an inner surface of the bottom portion of the metal case. 2. The surface-mounting rectangular storage cell according to claim 1, wherein a height of an inner peripheral wall portion of the insulating gasket is provided in a range of a thickness of the flange portion. 2. The surface-mounting rectangular storage cell according to claim 1, wherein a height of the outer peripheral wall portion of the insulating gasket is higher than a height of the inner peripheral wall portion. 2. The surface mounting according to claim 1, wherein an outer peripheral wall portion of the insulating gasket has a heat welded portion with the metal case , and a connecting portion of the insulating gasket does not have a heat welded portion with the metal case . Square energy storage cell. The surface-mounting rectangular storage cell according to claim 1, wherein a heat-welded portion between the outer peripheral wall portion of the insulating gasket and the metal case is provided on the outer surface of the flange portion. 2. The step board is configured such that at least one of the positive / negative terminal boards of the terminal board is bent stepwise in a direction away from the metal case except for a connection part with the metal case. A rectangular battery for surface mounting as described in 1. 2. The surface-mounting rectangular storage cell according to claim 1, wherein the surface of at least one of the metal case and the terminal plate is subjected to a roughening process for improving adhesion with an exterior resin.

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