Patent Application
20090061309
The present invention relates to a container for electric energy storage device for use in a chargeable battery or electric double layer capacitor, and a battery or electric double layer capacitor using the same. More specifically, the present invention relates to a thin battery used for small-sized electronic equipment such as cellular phones, a battery for an electric double layer capacitor for use in a backup power source of semiconductor memories, and stand-by power sources for electronic equipments, or an electric double layer capacitor and a container for electric energy storage device.
In recent years, along with remarkable development of portable equipment typically represented by cellular phones, portable computers, and camera-integrated video tape recorders, further decrease in the size and weight have been demanded. Then, also for the battery as the power source for such portable equipments, it has been demanded to increase the energy density and decrease the size and the weight of the battery.
Further, an electric double layer capacitor uses an electric double layer in which positive and negative charges are opposed and arranged at an extremely small distance at the boundary where different two phases (for example, solid electrode and electrolyte) are in contact with each other. The electric double layer capacitor is an electric device capable of charging and discharging electric energy by utilizing electrostatic adsorption and desorption of tons in the electric double layer.
Then, a thin secondary-battery or electric double layer capacitor in which electric energy storing elements including a positive electrode (first polarizable electrode) B-1, a negative electrode (or second polarizable electrode) B-2, and a separator B-3 (that is, battery elements or electric double layer capacitor elements) and an electrolyte B-4 are contained in a substrate 11 made of ceramics has been proposed in recent years as shown in
Charge and discharge in the battery and the electric double layer capacitor can be conducted by way of the first and the second electrodes C, D formed on the lower surface of the ceramic substrate 11 and the battery or the double layer capacitor can be connected by means of solder or the like on an external electric circuit board (refer, for example, to Japanese Unexamined Patent Publication JP-A 2004-227959 (pages 4 to 6, FIG. 1)).
Further, a thin solid electrolyte battery in which battery elements including a positive electrode B-1, a negative electrode B-2, and a solid electrolyte B-3 are contained in a container having a frame 21 made of ceramics, a metal bottom plate 22 and a lid member 23 as shown in
As shown in
However, in the battery or the electric double layer capacitor using the container for electric energy storage device shown in
Further, the solid electrolyte battery using the container for electric energy storage device shown in
Accordingly, the invention has been achieved in view of the foregoing problems and its object is to provide a container for electric energy storage device excellent in the manufacturing efficiency and easy for surface mounting to an external electric circuit board, as well as a battery and electric double layer capacitor at high performance using the same.
According to one of the invention, a container for electric energy storage device which contains electric energy storage elements comprises: a frame; a first sealing member bonded to the frame so as to close a first opening of the frame; and a second sealing member bonded to the frame so as to close a second opening of the frame and having a connection end portion disposed in a vicinity of the first sealing member.
Further, according to one of the invention, it is preferable that the second sealing member essentially consists of one plate member.
Further, according to one of the invention, it is preferable that the connection end portion is flush with the first sealing member.
Further, according to one of the invention, it is preferable that the connection end portion is outside of an outer lateral surface of the frame and in parallel with the first sealing member.
Further, according to one of the invention, it is preferable that the connection end portion in parallel with the first sealing member is disposed in a region which is on a periphery of the first opening and is inward the outer lateral surface of the frame.
Further, according to one of the invention, it is preferable that the connection end portion is bonded to the periphery of the first opening.
Further, according to one of the invention, it is preferable that the connection end portion is disposed at plural positions in symmetrical with respect to the center of the frame in a plan view.
Further, according to one of the invention, it is preferable that the frame essentially consists of alumina sintered body.
Further, in the invention, it is preferable that at least one of the first sealing member and the second sealing member is bonded by way of a frame-like member to the frame.
Further, according to one of the invention, it is preferable that at least one of the first sealing member and the second sealing member is bonded by way of metal containing aluminum as a main ingredient to the frame or the frame-like member.
Further, according to one of the invention, it is preferable that the bonding portion of the second sealing member has a narrower width region than other region of the bonding portion.
Further, according to one of the invention, it is preferable that the bonding portion of the second sealing member has a narrower width region on the side of the region where the connection end portion is disposed than other region of the bonding portion.
Further, according to one of the invention, it is preferable that an insulating material in at least one of the first sealing member and the second sealing member comprises an insulating material and a conductor film on an a surface of the insulating material.
Further, according to one of the invention, it is preferable that an insulating coat layer is coated on a first surface of the first sealing member opposite to a second surface of the first sealing member bonded to the frame.
According to one of the invention, a battery comprises: the container for electric energy storage device constituted as described above; a positive electrode and a negative electrode in the container for electric energy storage device, a separator interposed between the electrodes; and an electrolyte.
According to one of the invention, an electric double layer capacitor comprises: the container for electric energy storage device constituted as described above; two polarizable electrodes in the container for electric energy storage device, a separator interposed between the two polarizable electrodes; and an electrolyte.
In accordance with one of the invention, the container for electric energy storage device is a container for electric energy storage device containing electric energy storage elements and since it includes the frame, the first sealing member bonded to the frame so as to close the first opening of the frame, and the second sealing member bonded to the frame so as to close the second opening of the frame and having the connection end portion disposed in a vicinity of the first sealing member, the container for electric energy storage device can be placed on a surface of the external electric circuit board with the first sealing member being on the side of the external electric circuit board, and the first sealing member and the connection end portion of the second sealing member can be connected by a surface mounting method to the electrodes of the external electric circuit board upon mounting with no addition of connection means such as a connection lead for external connection thereby thereby capable of improving the operation efficiency for mounting.
In accordance with one of the invention, since the second sealing member essentially consists of a sheet of plate material, the second sealing member can be manufactured, fox example, by integrally punching out the second sealing member from a plate material and bending the same. Accordingly, a container for electric energy storage device with decreased number of manufacturing steps and excellent in the manufacturing efficiency can be provided.
In accordance with one of the invention, since the connection end portion is flush with the first sealing member, it can be easily surface mounted to the surface of a flat external electric circuit board.
In accordance with one of the invention, since the connection end portion is outside of an outer lateral surface of the frame and in parallel with the first sealing member, the area of connection between the connection end portion and the external electric circuit board is increased thereby enabling surface mounting at a higher bonding strength.
In accordance with one of the invention, since the connection end portion in parallel with the first sealing member is disposed in a region which is on a periphery of the first opening and is inward the outer lateral surface of the frame, the surface mounting area on the external electric circuit board can be decreased.
In accordance with one of the invention, since the connection end portion is bonded to the periphery of the first opening, the connection end portion is fixed to make the positional relation with the first sealing member constant and, accordingly, positioning with the electrode on the external electric circuit board can be facilitated to make the electric connection reliable.
In accordance with one of the invention, since the connection end portion is disposed to plural positions in symmetrical with respect to the center of the frame in a plan view, this can simplify the operation of judging the direction of attaching the battery or the like upon mounting the battery or the like using the container for electric energy storage device to the external electric circuit board.
In accordance with one of the invention, since the frame essentially consists of alumina sintered body, it is less corrosive to an electrolyte or the like injected to the inside to stabilize the performance of the battery or the electric double layer capacitor.
In accordance with one of the invention, since at least one of the first sealing member and the second sealing member is bonded by way of a frame-like member to the frame, the first sealing member or the second sealing member can be bonded easily to the frame.
In accordance with one of the invention, since at least one of the first sealing member and the second sealing member is bonded to the frame or the frame-like member by way of a metal containing aluminum as a main ingredient, aluminum is less corrosive to an electrolyte or the like contained in the battery or the electric double layer capacitor to stabilize the performance of the battery or the electric double layer capacitor.
In accordance with one of the invention, since the bonding portion of the second sealing member has a narrower width region than other region of the bonding portions, a path for releasing the pressure is restricted to a portion of narrow bonding width when the internal pressure of the battery and the electric double layer capacitor increases.
In accordance with one of the invention, since the bonding portion of the second sealing member has a narrower width region on the side of the region where the connection and portion is disposed than other region of the bonding portion, the path for releasing the pressure can be restricted to the side of the connection end portion. insulating material in at least one of the first sealing member and the second sealing member comprises an insulating material and a conductor film on a surface of the insulating material, various insulating materials such as a resin can be used for the first sealing member and the second sealing member.
In accordance with one of a first invention, since an insulating coat layer is coated on a first surface of the first sealing member opposite to a second surface of the first sealing member bonded to the frame, the area of bonding between the first sealing member and the external electric circuit board can be decreased.
In accordance with one of the invention, since the battery comprises the container for electric energy storage device of the constitution described above, a positive electrode and a negative electrode in the container for electric energy storage device, a separator intervened between the electrodes, and an electrolyte, a battery of easy surface mounting can be provided.
In accordance with one of the invention, since an electric double layer capacitor comprises the container for electric energy storage device of the constitution described above, the two polarizable electrodes in the container for electric energy storage device, a separator interposed between the two polarizable electrodes, and an electrolyte, an electric double layer capacitor of easy surface mounting can be provided.
Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings.
Now referring to the drawings, preferred embodiments of the invention are described below.
A container for electric energy storage device, as well as a battery or an electric double layer capacitor using the same according to the invention are to be described specifically.
In
In the drawings, reference numeral 1 denotes a frame made of an insulating material, reference numeral 1a denotes an inner space of the frame 1 in which battery elements or electric double layer capacitor elements (that is, electric energy storage elements) are contained, reference numeral 2 denotes a first sealing member (hereinafter also referred to as a bottom plate), reference numeral 3 denotes a second sealing member (hereinafter also referred to as a lid member), reference numeral 3a represents an extended portion of the second sealing member 3, reference numeral 3b denotes a connection end portion connected by way of the extended portion 3a to a main body 3c of the second sealing member 3, reference numeral 4a denotes a second conductor layer formed on the upper surface of the frame, and reference numeral 5a denotes a first conductor layer formed at the lower surface of the frame 1.
The container for electric energy storage device of the invention includes the frame 1 having openings at both upper and lower ends, a first sealing member (bottom plate) 2 jointed to the frame 1 so as to close the first opening of the frame 1 (lower end opening in the drawing), and a second sealing member (lid member) 3 having the connection end portion 3b bonded to the frame 1 so as to close the second opening of the frame 1 (upper end opening in the drawing) and having the connection end portion 3b disposed at a position near the first sealing member 2 in parallel therewith. Then, the extended portion 3b extended so as to be led from the main body 3c of the second sealing member 3, electrically connects the main body 3c of the second sealing member 3 and the connection end portion 3b.
That is, a container for electric energy storage device includes the bottom plate 2 having a conductive portion, the frame 1 jointed over the entire periphery at the outer periphery of the upper surface of the bottom plate 2, and the lid member 3 having the conductive portion bonded to the periphery of the second opening at the upper surface of the frame 1 so as to close the inner space 1a, and electric energy storage elements such as the battery elements or electric double layer capacitor elements are contained in the inner space 1a. In the container for electric energy storage device, the lid member 3 includes the main body portion 3c for closing the second opening, the extended end portion 3a, and the connection end portion 3b of the frame 1. The extended portion 3a is extended from the upper end of the frame 1 along the outer lateral surface of the frame 1 as far as the lower end of the frame 1 and connected at one end to the main portion 3c of the lid member 3 and connected at the other end to the connection end portion 3b.
Further,
As described above, in the container for electric energy storage device of the invention, the bottom plate 2 and the lid member 3 are bonded face to face with each other so as to sandwich the frame 1 therebetween and close the openings of both of the upper and lower ends of the frame 1, the electric energy storage elements are sealed in the inner space 1a surrounded by the frame 1, the bottom plate 2 and the lid member 3, the connected end portion 3b connected with the main body portion 3c of the lid member 3 is disposed along with the bottom plate 2, and formed such that the bottom plate 2 and the connection end portion 3b can be connected to the electrode of the external electric circuit board.
Further, it may also be in a configuration that the extended portion 3a is manufactured separately from the main body portion 3c of the lid member 3 and bonded to the main body portion 3c of the lid member 3. Further, it is not always necessary that the lower surface of the connection end portion 3b and the lower surface of the bottom plate 2 are just flush with each other and it may suffice that troubles are not caused upon connection with wiring conductors on the external electric circuit board by means of solder bonding.
Further,
In the container for electric energy storage device, and the battery or the electric double layer capacitor using the same of the invention, the frame 1 is made of an insulating material such as resin, glass or ceramics, and has a rectangular cylindrical, circular cylindrical or polygonal cylindrical shape. For the convenience of mounting on the external electric circuit board, the rectangular cylindrical shape facilitates design or the arrangement on the substrate. For example, the frame 1 is formed as a rectangular cylindrical shape with a length for one side of about 3 mm to 5 nm a, a height of about 1 to 1.5 mm and a thickness of about 0.4 mm and having openings on both of upper and lower end faces. Among them, ceramics are suitable as the insulating material for the container for electric energy storage device in view of good sealing property, chemical stability, as well and easy fabrication. Accordingly, while description is to be made on an example where the frame 1 is made of ceramics, the container for electric energy storage device can also be formed also in a case of using other insulating materials. For example, in a case of the resin, a liquid crystal polymer, modified polyamide, nylon resin, polypropylene, etc. can be used. Further, the frame 1 may be formed in any structure so long as it can electrically insulate the bottom plate 2 and the lid member 3 and may be formed, for example, by coating the surface of a metal with an insulating material, or sandwiching an insulating material between frame-shape metal members to insulate upper and lower portions.
For the frame 1, various kinds of ceramics, for example, alumina (aluminum oxide, Al2O3) sintered body, or aluminum nitride (AlN) sintered body or glass ceramics can be used. In a case that the frame 1 is made of the AlN sintered body, heat during operation can be dissipated efficiently to the outside. In a case of using alumina (aluminum oxide, Al2O3) sintered body, it is excellent in the mechanical strength and excellent in the electric insulation.
In a case where the frame 1 is made of alumina (aluminum oxide Al2O3) sintered body, the frame 1 is manufactured as described below. That is an appropriate organic binder, etc. are mixed to a starting powder such as Al2O3, silicon oxide (SiO2), magnesium oxide (MgO), and calcium oxide (CaO) to form a granular powder. The powder is charged in a mold, applied with press molding to manufacture a molded product of a cylindrical frame 1 such as of a rectangular cylindrical, circular cylindrical or polygonal cylindrical shape. The molded product is fired at 1500° C. to 1600° C., to manufacture the frame 1.
A metal paste containing, as a main ingredient, a powder of metal such as molybdenum (Mo) and manganese (Mn) is printed and coated on the periphery at the openings for both upper and lower ends on the upper surface and the lower surface, and other required portions of the frame 1 to form a metal paste layer as the second conductor layer 4a and the first conductor layer 5a, and they are fired at a temperature of about 1300° C. to 1500° C. Thus, the first conductor layer 5a and the second conductor layer 4a are formed on the upper surface and the lower surface of the frame 1.
When bonding the lid member 3 to the second conductor layer 4a and the bottom plate 2 to the first conductor layer 5a by brazing materials 4b and 5b, respectively, an Ni layer is preferably applied by a plating method to the second conductor layer 4a and the first conductor layer 5a. This can improve the wettability of the brazing materials 4b and 5b to the first conductor layer 5a and the second conductor layer 4a, to strengthen the bonding of the first conductor layer 5a and the second conductor layer 4a to the lid member 3 and the bottom plate 2.
Then, the bottom plate 2 is bonded to the first conductor layer 5a by the brazing material 5b. Further, after inserting the battery elements or the electric double layer capacitor elements into the inner space 1a of the container comprising the frame 1 and the bottom plate 2, the lid member 3 is bonded to the second conductor layer 4a by the brazing material 4b having a melting point lower by 30° C. or more than that of the brazing material 5b. As described above, the container for electric energy storage device of the invention is constituted by the frame 1, the bottom plate 2, and the lid member 3.
The bottom plate 2 and the lid member 3 are electroconductive for at least a portion thereof, that is, a portion in contact with the electric energy storage elements, a terminal portion connected to the external electric circuit board, and a portion for connecting the portion in contact with the electric energy storage elements and the terminal portion. Preferably, the portions are each made of a metal plate such as of stainless steel (SuS), Fe—Ni—Co alloy, or aluminum (Al) and are bonded to the frame 1 where Ni plating is applied to the surface of the second conductor layer 4a and the first conductor layer 5a by brazing materials 4a and 5b such as silver (Ag) brazing material, Ag-copper (Cu) brazing material, or Al brazing material. Al brazing material is used preferably for the brazing materials 4b and 5b for the lid member 3 and the bottom plate 2, particularly, for one to be used as the positive electrode. That is, in a case where the lid member 3 is used as the positive electrode, it is preferred that Ni plating is applied to the surface of the second conductor layer 4a, then the frame 1 and the lid member 3 are bonded by way of the Al brazing material 4b under a vacuum atmosphere or a reducing atmosphere by using Al brazing material as the brazing material 4b. Since Al brazing material is less corrosive to the electrolyte B-4, it can protect the second conductor layer 4a or the first conductor layer 5a and can suppress them from easily leaching into the electrolyte B-4 at a charge/discharge voltage to deteriorate the bonding strength.
Further, while the reliability of bonding is improved by bonding the bottom plate 2 and the lid member 3 by the brazing materials 4b and 5b to the frame 1, the bonding method is not restrictive. For example, they may be bonded by a resin adhesive, glass sealing material, etc. In a case of this bonding method, it is not necessary to form the second conductor layer 4a and the first conductor layer 5a to the frame 1 made of ceramics.
In the container for electric energy storage device comprising the frame 1, the bottom plate 2 and the lid member 3 manufactured as described above, plating layers 8a and 8b made of a metal excellent in the corrosion resistance and excellent in the wettability with the brazing material, specifically, an Ni layer of 1 to 12 μm thickness and a gold (Au) layer of 0.05 to 5 pa thickness are preferably deposited successively by a plating method or the like to the exposed portion of the second conductor layer 4a and the first conductor layer 5a of the frame 1, the exposed portion of the bottom plate 2 and the lid member 3, and the brazing bonded portion of the first conductor layer 5a and the bottom plate 2 (refer to
Further, in the bottom plate 2 and the lid member 3 exposed to the outside of the container for electric energy storage device, wettability with the solder is improved, bonding strength with the wiring conductor on the external electric circuit board is made more strong, thereby capable of preventing oxidative corrosion such as occurrence of rust. Further, the electric resistance value between the bottom plate 2 and the lid member 3 is decreased by the Au layer and the loss of the electric current generated from the battery or the electric double layer capacitor by the electric resistance can be prevented as much as possible.
In a case where the thickness of the Ni layer is less than 1 μm, it is difficult to prevent oxidative corrosion for each of the conductor layers or effectively suppress leaching of the metal ingredient from each of the conductor layers, and the performance of the battery or the electric double layer capacitor tends to be degraded. Further in a case where the thickness of the Ni layer exceeds 12 μm, it takes much time for forming plating and the mass productivity tends to be lowered.
Further, in a case where the thickness of the Au layer is less than 0.05 μm, it is difficult to form an Au layer of a uniform thickness tending to form a portion where the Au layer is extremely thin or a portion where the Au layer is not formed and tending to lower the effect of preventing the oxidative corrosion or the wettability with the solder. Further, in a case where the thickness of the Au layer exceeds 5 μm, it takes much time for forming plating and mass productivity tends to be lowered.
Preferably, after depositing to form the Ni layer and the Au layer, a corrosion resistant metal layer 7 made of a metal material not corrosive to the electrolyte B-4 is coated over the Au layer on the side of the inner space 1a of the container for electric energy storage device of the bottom plate 2 and the lid member 3 as shown in
Since Al, Zn, an alloy containing the metal as the main ingredient, Au, and SUS less leach to the organic solvent type electrolyte B-4, they are suitable particularly as the corrosion resistant metal layer 7 on the side of the positive electrode of the battery B or the electric double layer capacitor B.
Further, a metal containing Al as the main ingredient and containing 0.5 to 10% by weight of silicon (Si) is used preferably. By the use of the Al—Si alloy containing Al as the main ingredient, the bonding strength between the corrosion resistant metal layer 7, and the positive electrode B-1, and the negative electrode B-2 or the polarizable electrodes B-1 and B-2 by way of a conductive material such as a fluororesin containing carbon particles is increased, and the positive electrode B-1 and the negative electrode B-2, or the polarizable electrode B-1, B-2 can be bonded firmly to the bottom plate 2 and the lid member 3, as well as the electric connection can be improved.
The corrosion resistant metal layer 7 is formed, for example, by masking a wall of the frame 1 facing the inner space 1a by magnetically adsorbing a masking member made of stainless steel (SUS) so as to expose a predetermined range of the inner space 1a of the container for electric energy storage device, so that the second conductor layer 4a and the first conductor layer 5a are not in electric conduction, and forming the corrosion resistant metal layer 7 to a thickness of 0.2 to 40 μm by a vacuum deposition method or a sputtering method. For example, as shown in
Further, upon deposition of the corrosion resistant metal layer 7, the surface of the corrosion resistant metal layer 7 can be made rough such that the arithmetic mean roughness Ra is about from 0.1 μm to 3 μm, for example, by increasing the deposition rate of vacuum vapor deposition or sputtering, or applying etching after film deposition, thereby enabling to lower the resistance in the electric connection with the electric energy storage element.
In a case where the thickness of the corrosion resistant metal layer 7 is less than 0.2 μm, this results in a portion that cannot be completely covered with a sufficient thickness by the corrosion resistant metal layer 7 and the continuous film surface of the corrosion resistant metal layer 7 cannot sometimes completely cover a region from the surface of the second conductor layer 4a or the first conductor layer 5a to the lid member 3 or the bottom plate 2 bonded by way of the brazing material 4b, 5b of Ag brazing material, Ag—Cu brazing material, Al brazing material etc, so that the second conductor layer 4a or the first conductor layer 5a may be possibly corroded by the electrolyte B-4 used for the battery 8 or the electric double layer capacitor B. Further, in a case where the thickness of the corrosion resistant metal layer 7 exceeds 40 μm, this results in a disadvantage of taking much time for the formation of the film surface. Further, in a case where the thickness of the corrosion resistant metal layer 7 exceeds 40 μm, this may possibly result in a disadvantage of causing a stress due to the difference of thermal expansion coefficient between the corrosion resistant metal layer 7 and the bottom plate 2 or the lid member 3 to detach the corrosion resistant metal layer 7 from the bottom plate 2 or the lid member 3.
Then, as shown in
The width, the position, etc. of the extended portion 3a and the connection end portion 3b can be changed in accordance with the shape and the size of the wiring conductor of the external electric circuit board. For example, the main body portion 3c of the lid member 3 and the extended portion 3a may be of an identical width as shown in
Further, while the extended portion 3a is disposed at a central portion on one lateral surface of the frame 1, it may be disposed also to a corner put between adjacent two lateral surfaces of the frame 1. Further, the extended portion 3a may be disposed not being restricted to one position but, for example, may be disposed at a lateral surface and the opposing lateral surface on the side opposites thereto, or may be disposed to the entire four lateral surfaces or the entire four corners. In this case, the corners of the frame 1 may be chamfered and the extended portion 3a may be disposed to the chamfered surface at the corner when formed into an octagonal shape. As in the examples described above, in a case where the extended portions 3a are disposed at plural positions in symmetrical with respect to the center for the frame 1 in plan view, the mounting direction of the battery B or the electric double layer capacitor 8 can be aligned easily in the direction of the electrode of the external electric circuit board upon mounting the battery B or the electric double layer capacitor B, and they can be connected easily while conforming to the polarity of the wiring conductors of the external electric circuit boards so that mounting is facilitated further.
In
Further, in the embodiment shown in
Further, in
Further, as shown in
As described above, the bottom plate 2 and the lid member 3 function as sealing plates for sealing the openings of the frame 1, the conductive portion facing the inner space 1a serves as a collector or serves as a support member for supporting a metal film as the collector, and also has a function as a connection member for connecting with the wiring conductor on the external electric circuit board. As described above, while the bottom plate 2 and the lid member 3 are preferably made of a metal plate, they may be formed also by cutting a metal block, or can be formed also by rendering a necessary portion electroconductive. For example, as shown in
Further, due to the structure in which one side of the lid member 3 is bonded with the external electric circuit board by way of the extended portion 3a, in a case where the inner pressure increases, for example, by excess heating of the battery B or the electric double layer capacitor B and the bonded portion between the frame 1 and the lid member 3 is detached, the sides other than the side where the extended portion 3a extends tend to be detached, by which the scattering direction of the electrolyte B-4 can be controlled. Accordingly, by mounting important parts on the side of the extended portion 3a, damages due to scattering of the electrolyte B-4 can be minimized.
Further, as shown in
Further, as shown in
In
Further, the narrow width portion 1b may be disposed also by forming the width narrower for a portion of the frame 1.
Further, as shown in
In this case, the lid member 3 and frame-like member 6 are previously brazed to the frame 1, the battery elements or electric double layer capacitor elements are placed in a container comprising the frame 1 and the lid member 3, and the bottom plate 2 is sealed to the frame-like member 6 by a welding method such as seam welding or ultrasonic welding. As described above, by sealing the bottom plate 2 to the frame-like member 6 by the welding method such as seam welding or ultrasonic welding, the bonding operation of the bottom plate 2 can be facilitated. Since the extended portion 3a is extended from the lid member 3, it is preferred to previously bond and assemble the frame 1 and the lid member 3 and then, finally, bond and seal the bottom plate 2.
Further, it is not always necessary that the bottom plate 2 and the lid member 3 are flat plates and they may also be formed into a dish shape in which the outer peripheral portion is bent toward the frame 1, and may be bonded at the edge or the end face of the outer peripheral surface thereof to the frame 1. According to the constitution, the bent portion at the outer periphery has an effect of moderating the stress between the bottom plate 2 or the lid member 3 and the frame 1 in the same manner as in the case of providing the frame-like member 6 to provide a container for electric energy storage device suffering from less breakage such as cracks to the frame 1 by the stress.
Further, as shown in
Then, the battery B or the electric double layer capacitor B of the invention is to be described specifically.
The battery B of the invention has the container for electric energy storage device of the constitution described above, and battery elements as electric energy storage elements contained in the inner space 1a of the container for electric energy storage device, that is, a positive electrode B-1 and a negative electrode B-2, a separator B-3 interposed between the electrodes B-1 and B-2, and the electrolyte B-4.
More specifically, the battery B of the invention is formed, as shown in
While
Further, the electric double layer capacitor B of the invention has a container for electric energy storage device of the constitution described above, and electric double layer capacitor elements as the electric energy storage elements contained in the inner space 1a of the container for the electric energy storage device, that is, two polarizable electrodes B-1 and B-2, the separators B-3 interposed between the two polarizable electrodes B-1 and B-2, and the electrolyte B-4.
The electric double layer capacitor B of the invention is formed, more specifically, as shown in
In the battery B or the electric double layer capacitor B shown in
Then, a battery B or an electric double layer capacitor B having high reliability for air tight sealing and excellent in the mass productivity using the container for electric energy storage device of the invention can be obtained.
The positive electrode B-1 of the battery B is a plate-like or sheet-like electrode containing a positive electrode active substance such as LiCoO2 or LiMn2O4, and a conductive substance such as acetylene black or graphite, and the negative electrode B-2 is a plate-like or sheet-like electrode containing a negative electrode active substance made of a carbon material such as cokes or carbon fibers.
The positive electrode B-1 and the negative electrode B-2 are prepared by adding the conductive material described above to the positive electrode active substance or the negative electrode active substance, further adding and mixing a binder such as polytetrafluoroethylene or polyvinylidene fluoride to form a slurry, then molding them into sheet-like shape by using a well-known doctor blade method and then cutting the sheet, for example, into a circular or polygonal shape.
Further, the separator B-3 is formed of a non-woven fabric made of polyolefin fibers or a finely porous membrane made of polyolefin and is impregnated with the electrolyte B-4 and interposed between the positive electrode B-1 and the negative electrode B-2, thereby preventing contact between the positive electrode B-1 and the negative electrode B-2 and enabling movement of the electrolyte B-4 between the positive electrode B-1 and the negative electrode B-2.
The electrolyte B-4 of the battery B is composed of a lithium salt such as lithium tetrafluoroborate, or an acid such as hydrochloric acid, sulfuric acid, or nitric acid dissolved in an organic solvent such as dimethoxyethane or propylene carbonate.
Then, the first polarizable electrode B-1 and the second polarizable electrode B-2 of the electric double layer capacitor B of the invention is an electrode obtained, for example, by carbonating phenol resin fibers (novoloid fibers) and activating them. Activation is conducted by bringing the fibers into contact with an activation gas such as a high temperature steam under a high temperature atmosphere from 800 to 1000° C. The electrode is prepared by a step of gasifying a volatile ingredient or a portion of carbon atoms in the carbide thereby developing a fine structure mainly from 1 to 10 nm to increase the inner surface area to 1×106 m2/kg or more.
As described above, since the electric double layer capacitor B utilizes accumulation of charges to an electric double layer formed at the boundary between the two polarizable electrodes B-1 and B-2 described above, and the electrolyte B-4, extremely large electric charges corresponding to the surface area of the polarizable electrodes B-1 and B-2 can be accumulated unless the voltage exceeds a withstand voltage and the electrolyte B-4 causes electrolysis. The electric double layer capacitors are classified into two types, i.e., an organic solvent type and an aqueous solution type depending on the difference of the electrolyte B-4.
Particularly, in the electric double layer capacitor using the organic solution type can increase the driving voltage by 2 to 4 times as high as the aqueous solution type electric double layer capacitor using an aqueous solution such as an aqueous sulfuric acid solution for the electrolyte B-4. Since the storable electric energy E is represented as E=CV2/2 assuming the voltage as V and the capacitance as C, a high energy density can be obtained.
The electrolyte B-4 of the electric double layer capacitor B is composed of, for example, a lithium salt such as lithium hexafluoro phosphate (LiPF6) or a quaternary ammonium salt such as tetraethyl ammonium tetrafluoro borate ((C2H5)4NBF4) dissolved in a solvent such as propylene carbonate (PC) or sulfolane (SLF).
Further, for the separator B-3, glass fibers or heat resistant porous resins such as polyphenylene sulfide or polyethylene terephthalate or polyamide can be used for instance.
Then, an electric double layer capacitor B in which the inner space 1a of the container for electric energy storage device is airtightly sealed can be obtained by containing the polarizable electrodes-B-1 and B-2 and the separator B-3 in the inner space 1a of the container for electric energy storage device, then injecting the electrolyte B-4, for example, by using injection means such as a syringe from the upper surface of the inner space 1a of the frame 1 to which the lid member 3 is bonded and, after injection, air tightly bonding the bottom plate 2 to the opening in the inner space 1a of the frame 1.
While the electrolyte b-4 is highly corrosive and solubilizing property, since the frame 1, the bottom plate 2, and the lid member 3 has excellent corrosion resistance to the electrolyte B-4 by the use of the container for electric energy storage device of the invention, they are less corrosive to the electrolyte B-4 containing the organic solvent and the acid, so that the electrolyte B-4 is not degraded by the inclusion of impurities leaching out of the container for electric energy storage device into the electrolyte B-4 and the performance of the battery B or the electric double layer capacitor B can be maintained favorably.
The lid member 3 is made of a metal such as an Fe—Ni—Co alloy, SUS, or Al and the lid member 3 is bonded to the upper surface of the frame 1, by placing the lid member 3 to the upper surface of the frame 1 so as to cover the inner space 1a of the frame 1 and brazing them by a brazing material 4b, or by a seam welding method of rotationally moving a roller under current supply while pressing slightly along the edge of the upper surface of the lid member 3 and bonding the lid member 3 by the generated Joule heat, or by melting a previously deposited Ni layer and Al layer 4b to each of the surfaces of the lower surface of the lid member 3 and the second conductor layer 4a by ultrasonic welding, or by bonding with a resin adhesive or a glass sealing material.
Then, they are turned down with the lid member 3 being on the lower side and electric energy storage elements are placed in the inner space 1a defined by the lid member 3 and the frame 1. Finally, the battery B or the electric double layer capacitor B is manufactured by placing the bottom plate 2 made of a metal such as an Fe—Ni—Co alloy, SUS, or Al on the first conductor layer 5a at the upper surface of the frame 1 or the frame-like member 6 so as to cover the inner space 1a of the frame 1 and brazing them by a brazing material 5b, or by a seal welding method of rotationally moving a roller under current supply along the edge at the upper surface of the bottom plate 2, while pressing slightly and bonding the bottom plate 2 by the generated Joule heat, or by melting an Ni layer and an Al layer 5b deposited previously to each of the surfaces of the lower surface of the bottom plate 2 and the first conductor layer 5b, by ultrasonic welding, or bonding the bottom plate 2 to the frame 1 by a resin adhesive or a glass sealing material.
Further, in a case of making the bottom plate 2 of Al, forming the Al layer 5b on the first conductor layer 5a and adopting an ultrasonic welding method upon bonding the bottom plate 2 and the first conductor layer 5a, since the bottom plate 2 is bonded to the Al layer 5b on the first conductor layer 5a, the bonded portion between the frame 1 and the bottom plate 2 can be made less corrosive extremely to the electrolyte B-4.
That is, a passivation film of excellent corrosion resistance can be formed on the surface of the bonded portion between the bottom plate 2 and the first conductor layer 5a by the constitution described above, corrosion of the bonded portion between the bottom plate 2 and the first conductor layer 5a by the electrolyte B-4 or external atmosphere can be prevented extremely effectively to improve the reliability of airtight sealing in the inside of the battery B or the electric double layer capacitor B.
The bottom plate 2 may also be a plate-like member such as of an Fe—Ni—Co alloy or Ni—Co alloy formed at the lower surface thereof (on the side bonded with the frame 1) with an Al layer. Further, it is preferred that ridges (linearly protruded portions) are formed over the entire circumference at the outer periphery on the lower surface of the bottom plate 2. The ridges are arranged, in a case where the bottom plate 2 is a plate member made of Al, by forming ridges simultaneously upon punching the bottom plate 2 by a pressing machine or forming, for example, as a trigonal shape at a height of about 0.1 mm and downwardly protruded in the cross section by a so-called coining method after punching. The coining method is a method of restricting escape of the thickness by restraining the lateral aide of a work, stacking a mold formed with unevenness to the mold surface and the work to each other, and pressing them from above and below, thereby transferring an uneven pattern on the mold to the surface of the work.
Further, in a case where the bottom plate 2 is made of a plate member of an Fe—Ni—Co alloy or the like formed at the lower surface thereof with an Al layer, an ingot of the metal is rolled, for example, into a plate member of 0.2 to 0.5 mm thickness, in which an Al plate, for example, of 0.1 mm thickness is clad-bonded to the surface thereof and, thereafter, forming ridges by the coining method described above.
Then, when the bottom plate 2 is placed with the ridges formed on the outer periphery of the bottom plate being abutted to the upper surface of the frame 1 and ultrasonic waves at about several tens of kHz are applied from the upper surface of the bottom plate 2, the ridges at the lower surface of the bottom plate 2 are bonded to the Al layer 5b at the surface on the upper surface of the frame 1 while being crushed along the unevenness of the second conductor layer 5a and the Al layer 5b at the upper surface of the frame 1. In this case, even when the upper surface of the frame 1 is warped or undulated, they are bonded due to the difference for the degree of crushing of the ridges. Then, according to the ultrasonic bonding method, the bottom plate 2 can be bonded firmly without deteriorating the airtightness an the inner space 1a of the frame 1.
The ultrasonic bonding method is, more specifically, carried out, for example, as described below. That is, the ultrasonic bonding method is carried out by setting the upper surface of the frame 1 and the bottom plate 2 as the object of bonding between a horn having a chip to a lower portion at a top end as a medium of vibrations (angled fixing base) and an anvil, and applying ultrasonic vibrations in the horizontal direction at 15 to 30 kHz while moving continuously along the outer periphery of the bottom plate 2 under application of a pressure vertically, for example, at about 30 to 50 N by way of the chip. Further, it may be a method of conducting bonding for a predetermined length in a short time by adapting the shape of the chip as a linear form and increasing the pressure in the vertical direction.
In the ultrasonic bonding method, oxide membranes or contaminants at the surface of the bonded portion are pushed out in the outward direction of the bonded portion in an initial stage of applying the ultrasonic vibrations, and Al crystal grains at the bottom plate 2 and the upper surface of the frame 1 approach to each other till the inter-atom distance to generate inter-attraction between the atoms to obtain a strong bonding. In this case, a temperature of ⅓ or lower of the melting point of the metal in the usual method of melt bonding metal is generated locally, but such an extent of heat scarcely denatures the electrolyte B-4 and, accordingly, the working life of the battery B or the electric double layer capacitor B can be increased.
Further, according to the ultrasonic bonding method, other metals are scarcely diffused in Al and, accordingly, a bonded portion having further corrosion resistance to the electrolyte B-4 can be formed.
The invention is not restricted to the examples of the embodiments described above and can be modified variously within a range not departing from the gist of the invention.
Further, in the foregoing descriptions for the preferred embodiments, terms for up and down and right and left are used merely for explaining the positional relationship on the drawings and do not mean the positional relation in actual use.
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and the range of equivalency of the claims are therefore intended to be embraced therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-020454 | Jan 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/051421 | 1/29/2007 | WO | 00 | 7/28/2008 |
