Patent Application
20070182379
1. Field of the Invention
The present invention relates to a container designed for use with a rechargeable battery or an electric double layer capacitor, a battery or an electric double layer capacitor that employs the container, and an electronic device. More particularly, the present invention relates to a battery used in electronic apparatuses such as a mobile cellular telephone or an electric double layer capacitor used as a back-up power supply source of a semiconductor memory or a standby power supply source of an electronic apparatus, for example, to a container designed for use with such a battery or capacitor, and to an electronic device on which is mounted the container with the battery or capacitor housed therein.
2. Description of the Related Art
Shown in
The battery F or the electric double layer capacitor F of conventional design is constructed by housing, in a container, the positive electrode B-1 or the first polarizable electrode B-1 and the negative electrode B-2 or the second polarizable electrode B-2 having sandwiched therebetween the separator B-3 impregnated with the electrolyte B-4. The container is basically composed of a ceramic base body 11 made of, for example, sintered alumina (Al2O3) and a lid body 14 made of a metal material such as an iron (Fe)-nickel (Ni)-cobalt (Co) alloy. A hollow or open portion is formed in the ceramic base body 11 and also a metallized layer 12b is formed at the bottom facing the hollow or open portion. The electrodes B-1 and B-2, the separator B-3 sandwiched between the electrodes B-1 and B-2 are arranged between the metallized layer 12b and the lid body 14, and hermetically sealed in the container. Charging and discharging of the battery F or the electric double layer capacitor F are effected through a first electrode C and a second electrode D formed on the lower surface of the ceramic base body 11 that are connected to the lid body 14 and the metallized layer 12b respectively (for example, refer to Japanese Unexamined Patent Publication JP-A 2004-227959 (pages 4-6, FIG. 1).
However, in the above-described battery F or electric double layer capacitor F of the conventional design, two electrically conductive paths need to be formed inside the ceramic base body 11 by the routing of a metallized layer from the positive electrode B-1 or the first polarizable electrode B-1 to the second electrode D, as well as the routing of a metallized layer from the negative electrode B-2 or the second polarizable electrode B-2 to the first electrode C. This leads to a problem that a complex ceramic base body 11 and a production process of the ceramic base body 11 becomes complicated.
The invention has been devised in view of the problems mentioned above, and accordingly an object of the invention is to provide a container that is excellent in productivity, and to provide a high-performance battery or a high-performance electric double layer capacitor that employs the container and is thus surface-mountable onto the electric circuit board with ease, and to provide an electronic device.
The invention provides a container comprising:
a base body constituted of a side wall and a bottom portion, having a hollow or open portion for housing therein an electrical storage element;
an electrically conductive layer disposed on a bottom surface of the bottom portion facing the hollow or open portion;
a first electrode electrically connected to the electrically conductive layer, having a first electrode led-out portion which is led out to an upper surface of the side wall of the base body; and
a lid body having a second electrode formed on its upper surface and an electrically conductive portion formed on its lower surface, the second electrode and the electrically conductive portion being electrically connected to each other,
wherein the lid body is bonded to the upper surface of the side wall of the base body in such a manner as to cover the hollow or open portion.
According to the invention, the lid body has the second electrode formed on its upper surface and the electrically conductive portion formed on its lower surface, and the second electrode and the electrically conductive portion are electrically connected to each other. In this case, the base body only needs to have the first electrode formed thereon as a single-side electrically conductive path, and in contrast to the conventional construction, it is possible to simplify the process of manufacture of the base body. In addition, the routing of wiring from the electrically conductive portion of the lid body to the second electrode can be effected with ease only by connecting the upper surface and lower surface of the lid body. As a result, the container can be made suitable for mass production.
In the invention, it is preferable that the first electrode led-out portion is substantially flush with the second electrode.
In the invention, it is preferable that the first electrode led-out portion is disposed on an upper surface of a projection formed on the upper surface of the side wall of the base body so as to lie in juxtaposition with an opening of the hollow or open portion.
In the invention, it is preferable that the first electrode is connected to the electrically conductive layer by way of a through conductor formed inside the base body with its one end extended to the bottom surface facing the hollow or open portion.
In the invention, it is preferable that the junction between the first electrode and the through conductor is located at some midpoint between the bottom surface facing the hollow or open portion and the lower surface of the base body in the inside of the base body.
The invention provides a battery comprising:
the container mentioned above; and
an electrical storage element housed in the hollow or open portion, composed of a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte,
wherein the lid body is bonded to the upper surface of the side wall of the base body in such a manner as to cover the opening of the hollow or open portion,
wherein one of the positive electrode and the negative electrode is electrically connected to the electrically conductive layer, and the other of the positive electrode and the negative electrode is electrically connected to an electrically conductive portion formed on the lower surface of the lid body.
The invention provides a battery comprising:
a base body constituted of a side wall and a bottom portion, having a hollow or open portion;
an electrically conductive layer disposed on a bottom surface of the bottom portion facing the hollow or open portion;
a first electrode electrically connected to the electrically conductive layer, having a first electrode led-out portion which is led out to an upper surface of the side wall of the base body;
an electrical storage element housed in the hollow or open portion, composed of a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte; and
a lid body having a second electrode formed on its upper surface, the lid body being bonded to the upper surface of the side wall of the base body in such a manner as to cover the hollow or open portion,
wherein one of the positive electrode and the negative electrode is electrically connected to the electrically conductive layer, and the other of the positive electrode and the negative electrode is electrically connected to an electrically conductive portion formed on a lower surface of the lid body.
The invention provides an electric double layer capacitor comprising:
the container mentioned above; and
an electrical storage element housed in the hollow or open portion, the electrical storage element being composed of a first polarizable electrode, a second polarizable electrode, a separator interposed between the first polarizable electrode and the second polarizable electrode, and an electrolyte,
wherein the lid body is bonded to the upper surface of the side wall of the base body in such a manner as to cover the opening of the hollow or open portion,
wherein one of the first polarizable electrode and the second polarizable electrode is electrically connected to the electrically conductive layer, and the other of the first polarizable electrode and the second polarizable electrode is electrically connected to an electrically conductive portion formed on the lower surface of the lid body.
The invention provides an electric double layer capacitor comprising:
a base body constituted of a side wall and a bottom portion, having a hollow or open portion;
an electrically conductive layer disposed on a bottom surface of the bottom portion which bottom surface faces the hollow or open portion;
a first electrode electrically connected to the electrically conductive layer, having a first electrode led-out portion which is led out to the upper surface of the side wall of the base body;
an electrical storage element housed in the hollow or open portion, composed of a first polarizable electrode, a second polarizable electrode, a separator interposed between the first polarizable electrode and the second polarizable electrode, and an electrolyte; and
a lid body having a second electrode formed on its upper surface, the lid body being bonded to the upper surface of the side wall of the base body in such a manner as to cover the hollow or open portion,
wherein one of the first polarizable electrode and the second polarizable electrode is electrically connected to the electrically conductive layer, and the other of the first polarizable electrode and the second polarizable electrode is electrically connected to an electrically conductive portion formed on a lower surface of the lid body.
The invention provides an electronic device comprising:
a wiring substrate having a power source circuit wiring; and
the battery mentioned above, which is mounted onto the wiring substrate,
wherein the first electrode of the container and the second electrode formed on the upper surface of the lid body are connected, so as to face the wiring substrate, to the power source circuit wiring through an electrically conductive.
The invention provides an electronic device comprising:
a wiring substrate having a power source circuit wiring; and
the electric double layer capacitor mentioned above, which is mounted onto the wiring substrate,
wherein the first electrode of the container and the second electrode formed on the upper surface of the lid body are connected to the power source circuit wiring through an electrically conductive material so as to face the wiring substrate.
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 wherein:
Now referring to the drawings, preferred embodiments of the invention are described below.
Hereinafter, a detailed description will be given as to a container, a battery or an electric double layer capacitor which employs the container, and an electronic device according to the invention.
In the embodiments shown in
First of all, the container A of the invention will be explained in detail. Referring to
As shown in
The base body 1 is made of an insulative material such as ceramic, glass, and resin. The preferred examples thereof include sintered Al2O3, sintered mullite (3Al2O3.2SiO2), sintered aluminum nitride (AlN), glass ceramic, liquid crystal polymer, modified polyamide, nylon resin, polyethylene terephthalate, polypropyrene, polyphenylene sulfide, and so on. In the case of forming the base body 1 with use of sintered Al2O3, it is formed as follows. At the outset, suitable organic binder, solvent, and the like agent are admixed in a powdery raw material such as aluminum oxide (Al2O3), silicon dioxide (SiO2), magnesium oxide (MgO), calcium oxide (CaO) to obtain an insulative paste in the form of slurry. The insulative paste is formed into ceramic green sheets (a ceramic green sheet will hereafter be also referred to simply as “a green sheet”) by means of doctor blade method or calender rolling method. The ceramic green sheet is cut to a predetermined size. After that, among the ceramic green sheets, a plurality of selected ones are subjected to an appropriate stamping process to create the hollow or open portion 1a and the projection 2. In the following description as to the embodiments of the invention, the base body 1 will be illustrated as a ceramic-made construction. Note that the ceramic-made base body 1 may be formed into the same shape in a case where the other insulative material than sintered Al2O3 is used.
The base body 1 and the hollow or open portion 1a, for example, are not limited to a rectangular parallelepiped shape as shown in
The base body 1, when made of ceramic, is impervious to the electrolyte B-4 which contains an organic solvent, an acid, etc. Accordingly, it never occurs that impurities eluted from the base body 1 find their way into the electrolyte B-4, and thus the electrolyte B-4 hardly suffers from quality degradation. In the end, the container A constructed with use of ceramic will succeed in maintaining satisfactory battery performance. Alternatively, in the case of forming the base body 1 with use of sintered AlN, the base body 1 exhibits high thermal conductivity. This makes it possible to dissipate heat generated during operation to the outside in an efficient manner, and thereby prevent the electrolyte B-4 from being thermally denatured. Accordingly, the container A can be made highly reliable. Also in the case of constructing the container A with use of another insulative material such as resin, so long as the resin material is highly resistant to corrosion by the electrolyte B-4, high reliability can be attained.
Moreover, since the electrolyte B-4 is housed in the base body 1 made of a material that is excellent in hermeticity and heat resistance such as ceramic, even if the base body 1 is subjected to a temperature cycling test, it never occurs that a detachment is developed in the base body 1 and a bonded part between the base body 1 and the lid body 3 that will eventually cause a leakage of the electrolyte B-4. Further, with the excellent hermeticity of the base body 1, it is possible to prevent the intrusion of water, oxygen, or the like element, which causes battery performance degradation, into the electrolyte B-4 effectively.
Following the stamping process, a metal paste predominantly composed of powdery metal having a high melting point, such as tungsten (W), molybdenum (Mo), manganese (Mn) is print-coated onto predetermined areas of the green sheets. That is to say, onto these predetermined areas of the green sheets is print-coated the metal paste which constitutes the first electrically conductive layer 1b, the second electrically conductive layer 1c, and the first electrode 2d including the connection conductor 2b for providing electrical connection between the first electrically conductive layer 1b and the first electrode 2d led-out portion 2a. The second electrically conductive layer 1c is created in a case where the lid body 3 and the base body 1 are bonded together with use of a brazing filler metal. In this case, the second electrically conductive layer 1c needs to be spaced a certain interval away from the first electrode 2d led-out portion 2a. On the other hand, in a case where the lid body 3 and the base body 1 are bonded together with use of a resin adhesive for instance, the formation of the second electrically conductive layer 1c may be omitted. Note that the second electrically conductive layer 1c is not intended for passing electric current therethrough. However, when formed of a metallized layer, the second electrically conductive layer 1c possesses electrical conductivity, and is thus identified by the name.
Subsequently, a plurality of the green sheets to be formed into the base body 1 are brought into intimate contact with one another under a pressure of 4 to 5 MPa at a temperature of approximately 85° C. in advance of a firing process. At this time, as shown in
Lastly, the green sheet stacked body thus obtained is fired in a reduction atmosphere at a temperature of approximately 1600° C., whereupon the base body 1 is fabricated. The base body 1 constitutes a principal portion of the container A of the invention.
The configuration of the projection 2 can be either the one as shown in
It is particularly preferable that, as shown in
As another advantage, at the time of mounting the container A of the invention with the battery B or the electric double layer capacitor B onto the electric circuit board 100, as large a contact area as possible can be secured between the first electrode 2d led-out portion 2a formed on the upper surface of the projection 2 and the power source circuit wiring 101, 102 of the electric circuit board 100. Accordingly, the battery B or the electric double layer capacitor B can be fixedly emplaced on the electric circuit board 100 with stability.
The first electrode 2d is created as follows. Following the completion of formation of the green sheet stacked body which is formed into the base body 1, a metal paste prepared for forming the first electrode 2d is print-coated onto the green sheet stacked body by means of screen printing in a manner such that the first electrode 2d will extend from the side surface of the green sheet stacked body to the upper surface of the projection 2. Alternatively, as shown in
Note that a part of the first electrode 2d which is located on the side surface of the side wall 1d of the base body 1 may be divided into a plurality of portions. For example, instead of forming the castellation conductor 2d at the midportion of one side surface of the side wall 1d of the base body 1 as shown in
Moreover, as shown in
The through conductor may be so formed as to extend from the bottom surface facing the hollow or open portion 1a to the lower surface of the base body 1. In this case, however, the electrically conductive portion is exposed on the lower surface of the base body 1. Therefore, it is preferable that the connection conductor 2b is composed of a combination of a through conductor and an inner-layer conductor. The first electrode 2d is configured so as to lead out to the upper surface of the side wall 1d of the base body 1 by way of the through conductor and the inner-layer conductor located between the bottom surface facing the hollow or open portion 1a and the lower surface of the base body 1 in the inside of the base body 1. That is, the through conductor extends internally in the base body 1; to be more specific, internally in the bottom portion 1e, from the lower surface of the first electrically conductive layer 1b to some midpoint between the bottom surface facing the hollow or open portion 1a and the lower surface of the base body 1, and in turn the inner-layer conductor extends therefrom to the side surface of the base body 1. By doing so, the connection conductor 2b of the first electrode 2d is so formed as not to pass through a region between the side wall 1d and the bottom portion 1e (the bottom and side surfaces facing the hollow or open portion 1a) of the base body 1. Accordingly, the ceramic stacked body is less prone to peeling off in the attached region between the side wall 1d and the bottom portion 1c of the base body 1 because the electrically conductive layer is not formed therearound. This makes it possible to simplify the configuration of the insulative paste layer 4 as shown in
It is preferable that the first electrically conductive layer 1b, the second electrically conductive layer 1c, the first electrode 2d, and the first electrode 2d led-out portion 2a, each of which is formed in the base body 1, have their exposed surfaces plating with a layer of a metal material which is highly corrosion resistant and exhibits excellent wettability with respect to solder, to be more specific, a 1 to 12 μm-thick Ni layer. This makes it possible to protect each of the conductor portions in metallized form from oxidative corrosion, as well as to avoid elution of metal substances from the conductor portions.
If the thickness of the Ni layer is less than 1 μm, it becomes difficult to protect the conductor portions in metallized form from oxidative corrosion, as well as to avoid elution of metal substances from the conductor portions. As a consequence, the battery or the electric double layer capacitor is liable to deliver poor performance capabilities. By way of contrast, if the thickness of the Ni layer is greater than 12 μm, much time needs to be spent in applying the Ni-layer coating, thus causing a decrease in mass-productivity and an increase in electrical resistance.
It is more preferable that on the aforementioned Ni layer is additionally formed a 0.3 to 5 μm-thick, gold (Au)-made metal layer by means of plating or the like method. This makes it possible to enhance the wettability with respect to solder, as well as to avoid oxidative corrosion.
If the thickness of the Au layer is less than 0.3 μm, it becomes difficult to make the Au layer uniform in thickness. As a consequence, the Au layer is made unduly thin in part, or the Ni layer is liable to have an Au layer-absent part, thus lowering the effect of preventing oxidative corrosion and the wettability with respect to solder. By way of contrast, if the thickness of the Au layer is greater than 5 μm, much time needs to be spent in applying the Au plating layer, thus causing a decrease in mass-productivity.
The first electrically conductive layer 1b, although it is illustrated as being formed as a metallized layer, may be designed in another form so long as it is able to function as an electrical conductor which is resistant to corrosion by the electrolyte B-4. For example, the first electrically conductive layer 1b may be formed either by depositing a metal material which is resistant to corrosion by the electrolyte B-4, such as aluminum (Al), directly onto the bottom surface facing the hollow or open portion 1a by means of vapor deposition, or by coating an electrically conductive paste layer composed of an anti-corrosion resin material blended with electrically conductive particles onto the bottom surface facing the hollow or open portion 1a. Thus constructed, the first electrically conductive layer 1b is allowed to function as one current collector.
The application of the Au plating layer is especially advantageous if it is made on the surfaces of the first electrically conductive layer 1b and the second electrically conductive layer 1c formed inside the container A. That is, being impervious to the acidic electrolyte B-4, the Au plating layer serves to effectively prevent a major metal constituent of the first electrically conductive layer 1b as well as the second electrically conductive layer 1c, such as W, from dissolving easily into the electrolyte B-4 under the influence of a voltage produced in accompaniment with charging and discharging operations. Moreover, the Ni layer and the Au plating layer on the first electrode 2d serve to enhance the wettability with respect to solder, wherefore the strength of bonding between the first electrode 2d and the power source circuit wiring disposed on the surface of the electric circuit board (not shown in the figure) can be increased.
In the base body 1 thus constructed, the lid body 3 is bonded to the second electrically conductive layer 1c so as to cover the hollow or open portion 1a hermetically. In the lid body 3, at least the midportion of its lower surface is made to exhibit electrical conductivity to form the electrically conductive portion 3b, and on the upper surface thereof is formed the second electrode 3a which is electrically connected to the electrically conductive portion 3b. Note that, instead of forming the second electrically conductive layer 1c, it is possible to use a resin adhesive or the like to achieve bonding between the lid body 3 and the base body 1.
The lid body 3 is constructed by applying an electrically conductive material to the surface of a metal base such as Fe—Ni—Co alloy, Fe—Ni alloy, Al, or a ceramic base such as sintered Al2O3, sintered AlN, glass ceramic.
In the lid body 3 made of metal, the lower electrically conductive portion 3b and the upper electrode led-out portion are rendered electrically conductive so that the lid body 3 is able to function as intended. It is preferable that the lid body 3 has its surface plating with a protective layer such as an Ni layer, an Au layer, an Al layer. In order to bring the lid body 3 out of electrical contact with the first electrode 2d led-out portion 2a, the lid body 3 is bonded to the base body 1 in a manner such that its outer periphery is spaced a certain interval away from the projection 2. The separation between the lid body 3 and the first electrode led-out portion 2a is achieved by creating a spacing between the lid body 3 and the first electrode 2d at the time of bonding, or by placing an insulating member such as a resin plate therebetween.
In the lid body 3 made of metal, further, one side surface and part of the upper surface thereof that are close to the first electrode 2d led-out portion 2a may be subjected to insulation treatment. In this case, the lid body 3 can be bonded to the upper surface of the base body 1 without the necessity of spacing apart the lid body 3 and the first electrode 2d led-out portion 2a. Examples of the insulation treatment include formation of an insulating layer with use of resin. In the case of forming a resin-made insulating layer on the aforementioned part of the upper surface of the lid body 3, it is preferable that the electrically conductive second electrode 3a located on the upper surface of the lid body 3 is made substantially equal in area to the first electrode 2d led-out portion 2a. In this case, at the time of bonding the container A to the electric circuit board 100 by means of soldering, the surface tension of solder corresponding to the second electrode 3a and that corresponding to the first electrode led-out portion 2a are kept in balance. This helps prevent the container A from being positionally deviated from a predetermined mounting location.
On the other hand, in the lid body 3 made of ceramic, in that part thereof which provides electrical connection between the electrically conductive portion 3b and the second electrode 3a is formed a metallized layer made of W, Mo, Mn, or the like material, or formed a metal thin layer, such as an Al layer, by means of sputtering or=vapor deposition. In this case, on the surface of the lid body 3 made of sintered Al2O3, for example, is formed a metallized layer made of metal having a high melting point such as W, Mo, Mn. Moreover, in order to establish electrical connection between the electrically conductive portion 3b and the second electrode 3a, the electrically conductive portion 3b and the second electrode 3a are connected to each other by a through conductor or an electrically conductive path. The electrically conductive path is so formed as to extend from the electrically conductive portion 3b through the side surface of the lid body 3 to the second electrode 3a by applying a metal layer such as a metallized layer over the surfaces of the lid body 3.
In this case, the metallized layer formed in the lid body 3 should preferably be analogous to the ones for constituting the first electrically conductive layer 1b, the second electrically conductive layer 1c, and the first electrode 2d. This allows the shared use of a metal paste prepared for use, wherefore the metallized layers can be produced in an efficient manner. Moreover, it is preferable that, like the first electrically conductive layer 1b and the second electrically conductive layer 1c, that part of the metallized layer which lies on the lower surface of the lid body 3 has its surface plating with an Ni layer and according to need, an Au layer on the Ni layer, or plating with Al or the like substance by a conventionally known technique such as a sputtering method, a vapor deposition method. This makes it possible to effectively protect the metallized layer formed on the lower surface of the lid body 3 against corrosion, as well as to impart excellent wettability with respect to a brazing filler material, such as Ag brazing filler, Au-tin (Sn) solder, to the second electrode 3a formed on the upper surface of the lid body 3. As a result, the lid body 3 and the first, second power source circuit wiring 101, 102 of the electric circuit board 100 can be bonded together more firmly.
Thus, the metallized layer or metal thin layer of the lid body 3 is fixed to the second electrically conductive layer 1c of the base body 1 by way of a bonding material such as Al brazing filler, silver (Ag) brazing filler, Ag-copper (Cu) brazing filler, Au-tin (Sn) solder.
It is preferable that, as shown in
Note that the lid body 3 assembly may be composed of a platy ceramic base having formed at its midportion a through hole drilled all the way through from the upper main surface to the lower main surface of the ceramic base. In the through hole is fitted a metal plate. In this case, since the side surfaces of the lid body 3 possess insulation properties, there is no possibility of occurrence of electrical short circuit between one side surface of the lid body 3 and the first electrode led-out portion 2a.
In the container of the invention, if the corrosion resistance of the first electrically conductive layer 1b is found to be insufficient, as shown in
It is also preferable that the second electrically conductive layer 1c has its surface plating with a protective metal layer such as an Al layer, too. This makes it possible to render the second electrically conductive layer 1c resistant to corrosion by the electrolyte B-4, wherefore the desired performance capabilities of the battery B or the electric double layer capacitor B can be maintained satisfactorily. Note that, in the embodiments shown in
In the case of applying a coating of the insulative paste layer 4, the protective metal layer 5 is so formed as to extend over the upper part of the first electrically conductive layer 1b with the insulative paste layer 4 as well as the bottom surface facing the hollow or open portion 1a. In addition, the protective metal layer 5 is so formed as to extend over the upper surface of the second electrically conductive layer 1c as well as the upper part of the inner surface facing the hollow or open portion 1a located on the side wall 1d of the base body 1. The protective metal layer 5 is formed as follows. At the outset, a masking member is placed at a predetermined location to secure a protective metal layer 5-free region. The masking member is made of stainless steel (SUS) or Fe—Ni alloy, for example. With the masking member kept in place, a sputtering or vapor deposition process is performed on the target areas.
As shown in
In this way, the first electrically conductive layer 1b and/or the second electrically conductive layer 1c can be entirely surrounded by the protective metal layer 5, and there by protected against corrosion by the electrolyte B-4.
As described heretofore, according to the invention, the container A having the battery B or the electric double layer capacitor B is mounted with top side down. That is, the battery B or the electric double layer capacitor B is mounted with its one surface illustrated as the upper surface in
Moreover, in the container A thus constructed, by forming the second electrode 3a in the lid body 3, it is possible to simplify the process of manufacture of the base body 1, and thereby make the container A suitable for mass production. In addition, the lid body 3 is given a simple configuration and is thus suitable for mass production.
As has already been described, it is preferable that the first electrode 2d led-out portion 2a formed on the upper surface of the projection 2 and the second electrode 3a of the lid body 3 are arranged substantially flush with each other. In this case, as shown in
Note that the first electrode led-out portion 2a and the second electrode 3a do not necessarily have to be arranged exactly flush with each other. That is, these two components may be arranged substantially flush with each other so long as the container A can be surface-mounted onto the electric circuit board 100 properly without causing any problem, or, for example, so long as proper electrical connection can be established with use of an electric connecting member such as solder. Even if there is a difference in surface level between the first electrode 2d led-out portion 2a and the second electrode 3a, insofar as the difference is so slight, for example as small as 0.3 mm, the first electrode 2d and the second electrode 3a can be connected readily to the first power source circuit wiring 101 and the second power source circuit wiring 102, respectively, of the electric circuit board 100 in a usual manner using solder. In this regard, by reducing the thickness of the lid body 3 to approximately 0.3 mm or below, it is possible to realize the container A of the invention without the necessity of forming the projection 2.
In a case where the first electrode 2d led-out portion 2a and the second electrode 3a are not arranged substantially flush with each other, in order to establish proper connection with the first and second power source circuit wirings 101 and 102 on the electric circuit board 100, there is interposed a connection member designed to make up for the difference in surface level.
Meanwhile, with the lid body 3 made of metal or other materials having excellent thermal conductivity, even if heat is generated in the battery element or the electric double layer capacitor element housed in the container A during operation of the battery B or the electric double layer capacitor B, the generated heat can be dissipated from the lid body 3 to the electric circuit board 100 in an efficient manner. Accordingly, the battery B or the electric double layer capacitor B is able to offer improved operability without sustaining a significant temperature rise.
Next, the battery B or the electric double layer capacitor B will be described in detail according to the invention. Referring to
Note that the positive electrode B-1 and the negative electrode B-2 can be arranged in the place of each other. In this case, the negative electrode B-2 is emplaced on and electrically connected to the first electrically conductive layer 1b, whereas the positive electrode B-1 is emplaced on and electrically connected to the lid body 3.
On the other hand, referring to
By virtue of the container A of the invention, the battery B or the electric double layer capacitor B can be readily connected to the electric circuit board 100 by a surface-mounting technique with high reliability in hermeticity. Moreover, impurities are hardly dissolved into the electrolyte B-4. Thus constructed, the battery B or the electric double layer capacitor B is capable of effecting charging and discharging with stability.
The positive electrode B-1 of the battery B of the invention is an electrode made in the form of a plate or a sheet which contains a cathode active material composed of LiCoO2 or LiMnO4 for example, and an electrically conductive material including acetylene black or black lead. On the other hand, the negative electrode B-2 is an electrode made in the form of a plate or a sheet which contains an anode active material composed of a carbon material including coke or carbon fiber.
More specifically, the positive electrode B-1 is formed as follows. At first the cathode active material and the electrically conductive material are mixed together. Then, a binder including polytetra fluoroethylene or polyvinylidene fluoride is added to the admixture to form a slurry. The slurry is shaped into a sheet-like body by a conventionally known technique including a doctor blade method or a roller molding method. Lastly, the sheet body is subjected to cutting to obtain, for example, a polygonal or circular shape.
Similarly, the negative electrode B-2 is formed as follows. At first a binder including polytetra fluoroethylene or polyvinylidene fluoride is admixed in the anode active material to form a slurry. The slurry is shaped into a sheet-like body by a conventionally known technique including a doctor blade method or a roller molding method. Lastly, the sheet body is subjected to cutting to obtain, for example, a polygonal or circular shape.
For example, the separator B-3 is formed of a nonwoven cloth made of polyolefin fiber or a polyolefin-made fine porous membrane. Following the impregnation of the separator B-3 with the electrolyte B-4, the separator B-3 is interposed between the positive electrode B-1 and the negative electrode B-2 to avoid direct contact therebetween. Moreover, the separator B-3 allows the movement of the electrolyte B-4 between the positive electrode B-1 and the negative electrode B-2, thereby allowing the passage of electric current therethrough.
For example, the electrolyte B-4 is prepared by dissolving lithium salt such as lithium borate tetrafluoride, and an acid such as hydrochloric acid, sulfuric acid, nitric acid in an organic solvent including dimethoxyethane or propylene carbonate.
The first polarizable electrode B-1 and the second polarizable electrode B-2 in the electric double layer capacitor B according to the invention are obtained by carbonizing and activating phenol resin fiber (novoloid fiber), for example, and are fabricated in a process in which the activation is carried out by causing the fiber to come in contact with an activation gas such as a high temperature steam in a high temperature atmosphere at 800 to 1000° C., and a volatile component in a carbide or a part of a carbon atom is changed into a gas, and a fine structure having a size of 1 to 10 nm is mainly developed to set an internal surface area to be 1×106 m2/kg or more. In the electric double layer capacitor B according to the invention, the first and second electrodes 2a and 3a have no polarity, and the first electrode 2a side can be used as an anode and the second electrode 3a side can be used as a cathode, and they can also be used in reverse polarities.
For example, the electrolyte B-4 of the electric double layer capacitor B is prepared by dissolving lithium salt such as lithium hexafluorophosphate (LiPF6), or quaternary ammonium salt such as tetraethyl ammonium tetrafluoroborate ((C2H5)4NBF4) in a solvent including propylene carbonate (PC) or sulfolane (SLF).
For example, the separator B-3 is formed of glass fiber or a heat-resistant porous resin material such as polyphenylene sulfide, polyethylene terephthalate, polyamide.
Following the placement of the first polarizable electrode B-1, the second polarizable electrode B-2, and the separator B-3 in the container A, the electrolyte B-4 is poured into the container A from the opening of the hollow or open portion 1a by means of a syringe, for example. Upon the completion of the charging, the lid body 3 is air-tightly welded to the upper surface of the side wall 1d in such a manner as to cover the hollow or open portion 1a. In this way, there is obtained the electric double layer capacitor B having the container A which does not permit the passage of air.
The electric double layer capacitor B thus constructed is operated by exploiting accumulation of electric charge in an electric double layer formed at the interface between the two polarizable electrodes B-1 and B-2 and the electrolyte B-4. Therefore, unless the electrolyte B-4 undergoes electrolysis at a voltage exceeding a withstand voltage, it is possible to accumulate as great electric charge a possible in correspondence with the surface area of the polarizable electrodes B-1 and B-2.
The feature of the electric double layer capacitor B is especially advantageous if it employs an organic solution. In this case, it is possible to obtain a driving voltage 2 to 4 times as large as in the electric double layer capacitor B which employs an aqueous solution such as a sulfuric acid solution as the electrolyte. The maximum permissible accumulation of electric energy E is given by the formula: E=CV2/2, wherein V represents voltage and C represents capacitance. It will thus be seen that the electric double layer capacitor B is capable of providing high energy density.
The electrolyte B-4 of the battery B or the electric double layer capacitor B is essentially highly corrosive and soluble. In this regard, according to the container A of the invention, the base body 1 is impervious to the electrolyte B-4 which contains an organic solvent, an acid, etc. Moreover, it never occurs that impurities eluted from the container A find their way into the electrolyte B-4, wherefore the electrolyte B-4 is free from quality degradation. Accordingly, the battery performance can be maintained at a satisfactory level.
Moreover, according to the container A of the invention, the battery B or the electric double layer capacitor B is surface-mountable in such a manner that the first electrode 2d led-out portion 2a and the second electrode 3a are disposed on a side facing the surface of the electric circuit board 100 so that the first electrode 2d led-out portion 2a and the second electrode 3a face the electric circuit board 100. In this case, the surface having the first electrode 2d and the second electrode 3a can be electrically connected readily to the first power source circuit wiring 101 and the second power source circuit wiring 102 disposed on the electric circuit board 100. This makes it possible to reduce a size of the power source circuit disposed on the electric circuit board 100. Moreover, the battery B or the electric double layer capacitor B can be surface-mounted onto the electric circuit board 100 together with another electronic component, which results in an electronic device exhibiting high productivity. Further, the battery B or the electric double layer capacitor B can be placed in the vicinity of the electronic component, wherefore the electronic component is able to exhibit enhanced responsiveness.
While the invention has been shown in several forms by way of embodiments, it is not so limited but is susceptible of various changes and modifications without departing from the spirit and scope of the claimed invention. For example, although the above description deals with the case where the container A used for the battery B or the electric double layer capacitor B is provided with a single hollow or open portion 1a, the container A may be provided with a plurality of concavities 1a. In this case, it is possible to provide either a single lid body 3 for covering the concavities 1a as a whole or a plurality of lid bodies 3 for covering the concavities 1a on an individual basis. In the container A having a plurality of concavities 1a, by connecting the batteries B or the electric double layer capacitors B arranged in the concavities 1a in parallel with one another, it is possible to achieve high-capacitance characteristics. Alternatively, by connecting them in series with one another, it is possible to allow the battery B to provide a high voltage.
Note that, in the above description, the words such as “upper”, “lower”, “side”, “bottom” are used solely for the purpose of illustrating the embodiments of the invention with reference to the accompanying drawings, and therefore they do not stand for any positional relationship of the constituent components in actual use of the invention.
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 |
|---|---|---|---|
| P2005-218534 | Jul 2005 | JP | national |
| P2006-202160 | Jul 2006 | JP | national |
