JP2004047161A - Secondary battery and battery pack using the same - Google Patents

Abstract

An object of the present invention is to provide a secondary battery using a polymer-metal composite film for an outer package which has improved adhesion between battery elements, reduces expansion of the battery even when gas is generated, and has good cycle characteristics and output.
A secondary battery having a battery element covered with a polymer-metal composite film, comprising a battery element holding means.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a secondary battery, and more particularly to a secondary battery in which the adhesiveness of battery elements is improved to improve battery output and cycle characteristics.
[0002]
[Prior art]
2. Description of the Related Art In recent years, carbon dioxide emission regulations have been urgently demanded against the background of a growing environmental protection movement. In the automotive industry, electric vehicles (EV) and hybrid vehicles (HEV) have been replaced with vehicles using fossil fuels such as gasoline vehicles. In order to promote the introduction of fuel cell vehicles (FCV), the development of motor driving batteries, which are key to their practical use, has been earnestly carried out. A secondary battery that can be repeatedly charged is used for such a motor driving western battery because long-term replacement is unnecessary. In particular, when a high output and a high energy density are required, such as motor drive of EV, HEV, and FCV, it is common to use an assembled battery constituted by connecting a plurality of batteries in series. .
[0003]
As a secondary battery suitable for this method, a lithium ion secondary battery which is a small battery having a high output and a high energy density and easy to handle, particularly a battery element made of a polymer-metal composite film having a high energy density and a light weight. Promising is a thin lithium-ion secondary battery equipped with a lithium ion battery. It is well known that the distance between the positive electrode, the separator, and the negative electrode of a lithium ion secondary battery is important for the cycle characteristics and output, and as means for solving the problem, JP-A-11-219731 and JP-A-2000-357535 disclose it. There is.
[0004]
However, in a secondary battery using a polymer-metal composite film for the exterior, the exterior material has no strength unlike a can, and thus the structure described in JP-A-11-219731 and JP-A-2000-357535 is used. Cannot have the same structure as In the case of a secondary battery using a polymer-metal composite film for the exterior, the electrolytic solution evaporates during use at high temperatures, the distance between battery elements increases, and the battery expands and the cycle characteristics and output deteriorate. Would. In addition, a secondary battery using a polymer-metal composite film for the exterior is not limited to a lithium ion secondary battery, and the same applies to a bipolar battery or the like in that the output is improved by closely attaching battery elements.
[0005]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems, and improves the adhesion between battery elements, reduces the expansion of the battery even when gas is generated, and uses a polymer-metal composite film for an exterior having good cycle characteristics and output. It is an object of the present invention to provide a rechargeable battery.
[0006]
[Means for Solving the Problems]
The above object is achieved by a secondary battery having a battery element packaged with a polymer-metal composite film, the secondary battery comprising a battery element holding means.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The secondary battery that can be used in the present invention is not particularly limited as long as it is a secondary battery in which a battery element is packaged with a polymer-metal composite film, and has a configuration of a positive electrode, a separator, a negative electrode, an electrolytic solution or a gel electrolyte. The present invention can also be applied to a bipolar battery configured by stacking unit cells including a lithium ion secondary battery, a positive electrode, a negative electrode, and a solid electrolyte.
[0008]
Particularly desirable is a lithium ion secondary battery that easily generates gas.
[0009]
The term "battery element" used herein refers to a configuration including a positive electrode, a separator, and a negative electrode in a lithium ion secondary battery, and a configuration including a positive electrode, a negative electrode, and a solid electrolyte in a bipolar battery.
[0010]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 7 show a secondary battery of the present invention. The main configuration is basically the same as the prior art. Therefore, in the following, a characteristic part of the present invention is extracted and described, and other parts are omitted.
[0011]
As described in claim 2, the holding means is composed of two or more plate materials and the plate material connecting means. As an example, FIG. 1A is a perspective view showing the structure of a battery element including two plate members and a sandwiching means composed of the plate member coupling means, and FIG. FIG. 4 is a front view showing the structure of a battery element including the plate member of FIG. As for the structure of the battery element provided with the holding means shown in FIG. 1, the battery element 1 is held by using two plate members 2 which are one of the holding means, and the battery element 1 and the plate member 2 are joined by the plate member connecting means. The tape 3 is wound and joined. Here, a tape is used for the plate material connecting means, but the battery element 1 and the plate material 2 are, for example, fastened with rubber, tied with a band, sandwiched with a clip, and tied with a string using rubber, a band, a clip, a string, or the like. Alternatively, they may be combined (fixed).
[0012]
Here, metal can be suitably used as the plate material.
[0013]
For example, a tape, a rubber, a band, a clip, a string, or the like can be suitably used as the plate material coupling unit. As the material, it has corrosion resistance to the electrolytic solution and the electrolyte, and the adhesive force and the elasticity of the tape or rubber of the plate material joining means decrease due to the rise of the battery temperature (to about 60 ° C.), and the pinching effect is reduced. The material is not particularly limited as long as it is excellent in heat resistance so as not to decrease. In the case of a tape, a band, and a string, for example, a plastic such as polyvinyl chloride can be used. In the case of rubber, various rubber materials such as natural rubber and synthetic rubber can be used. In the case of the clip, for example, a material such as a U-shaped metal or a plastic such as polypropylene (PP) or polyethylene (PE) can be used.
[0014]
The plate material forming the holding means may be a current collector of each electrode, a terminal, or a combination thereof. That is, two or more plate members constituting the holding means are: (1) a positive electrode current collector and a negative electrode current collector, respectively; (2) a positive electrode terminal and a negative electrode terminal (see FIG. 1); Body, negative electrode current collector, positive electrode terminal and negative electrode terminal, (4) each positive electrode current collector and negative electrode terminal, and (5) each negative electrode current collector and positive electrode terminal. It should not be.
[0015]
When used as an electrode or a current collector, the size of the plate material may be any size that can be used for the electrode or the current collector. When a plate material is used separately from the electrodes and the current collector, the size may be appropriately determined so that the object of the present invention can be achieved. Having the same size is convenient for joining by the plate joining means.
[0016]
When the plate is used as an electrode or a current collector, the thickness of the plate may be any thickness that can be used for the electrode or the current collector. When a plate material is used separately from these electrodes and current collectors, the thickness may be appropriately determined so that the object of the present invention can be achieved. A range of 0.5 to 1.0 mm is easy to use, but should not be limited to this range.
[0017]
Further, as shown in FIG. 1, a flat plate material can be used as the plate material, and in order to further enhance the effect as a clamping means, the plate material is curved inward as shown by a dashed line in FIG. 2 (b). It is also possible to use a flat plate material (warped in a concave shape) and to make it flat by the coupling means (in this way, a larger compressive force is applied as compared with the case where a flat plate material is used from the beginning, and the battery In order to achieve the object of the present invention, for example, the adhesion between the elements can be further improved, a plate material having an appropriate shape can be used. Further, as shown in FIG. 4 and the like, the cross-section may have a U-shape, or as shown in FIG. Is not particularly limited.
[0018]
Further, in order to prevent short circuit due to conduction, the plate material coupling means needs to be an insulator. Therefore, when a metal is used as the material such as a clip or the like, it is necessary to form an insulator by forming an insulating film (such as an insulating coating film or an insulating film) or an insulating coating layer on the metal surface. .
[0019]
Further, in order to uniformly apply pressure to the electrode, it is desirable that the plate material constituting the holding means immediately above the electrode is flat. Therefore, it is desirable that one or more flat plate-like members (spacers) or the above-mentioned plate material is further sandwiched between the plate material (compression material) and the electrode, which constitute the clamping means, as another kind of the clamping means. On the other hand, as described above, it is desirable to use an inwardly curved (curved in a concave shape) plate material (compression material) as a plate material (compression material) forming the outer holding means (FIG. 2B and FIG. 3 (b), see the plate indicated by the dashed line).
[0020]
Further, there is a space between the side of the battery element and the exterior material of the polymer-metal composite film, and the gas is stored there. Therefore, expansion of the battery at the time of gas generation can be reduced. x In this case, since the interior of the exterior material is evacuated to a negative pressure at the stage of producing the battery, gas comes out of this space. As a result, gas can be prevented from accumulating in the battery element, and expansion of the battery can be suppressed.
[0021]
In addition, as described in claim 3, the coupling means, which is one of the holding means, engages the projection of one of the at least one plate with the hole of the at least one other plate.
[0022]
As an example, FIG. 2A is a perspective view showing a structure of a battery element including the holding means of the first embodiment, and FIG. 2B is a perspective view of A in FIG. 2A. FIG. 2C is a cross-sectional view taken along the line A, FIG. 2C is a front view of FIG. 2A, and FIG. 2D is an enlarged view of the hooking portion of FIG. is there.
[0023]
As for the structure of the battery element having the holding means shown in FIG. 2, the battery element 1 is held by using two plate members 2 which are one of the holding means, and one of the plate members 2a serves as a plate member connecting means. The four projections 4 provided in the above are engaged with the four holes 5 of the other plate member 2b.
[0024]
More specifically, as shown in FIG. 2D, the claw-shaped (hook-shaped or L-shaped) hooking portion 4a at the tip of the projection 4 provided on one corner of one plate member 2a is inserted into the hole 5, and The engaging portion 4a projecting to the opposite side of the portion 5 is shifted laterally (slid) to engage the engaging portion 4a with the other plate 2b. If necessary, the hole 5 may be closed with a suitable filler or the like after the engagement so that the engaging portion 4a does not slip out of the hole 5 after the engagement.
[0025]
When the projection 4 is provided on one plate 2a, as shown in FIG. 2 (a), the projection 4 may be fitted or welded into the hole of the one plate 2a. No particular limitation is imposed, for example, it may be molded integrally.
[0026]
Next, FIG. 4A is a perspective view showing the structure of a battery element provided with the holding means of the second embodiment, and FIG. 4B is a sectional view taken on line AA of FIG. FIG. 4C is a cross-sectional view taken along a line, and FIG. 4C is an enlarged view of a hooked portion in FIG.
[0027]
Regarding the structure of the battery element provided with the holding means of FIG. 4, the battery element 1 is held by using two plate members 2 which are one of the holding means, and the cross section of FIG. In the figure, one plate member 2a having a U-shaped cross section inserts three hook-shaped protrusions 4a provided on one side surface into three hole portions 5a having the same side surface of the other plate member 2b also having a U-shaped cross section. At the same time, the other plate member 2b is formed by inserting and hooking three hook-shaped projections 4b provided on the opposite side surface into three hole portions 5b of one plate member 2a on the same side surface. Thus, the positions of the hook-shaped projections and the holes are determined so that pressure is applied to the sandwiched battery element 1.
[0028]
FIG. 5A is a perspective view showing the structure of a battery element including the holding means of the third embodiment, and FIG. 5B is a view taken along line AA in FIG. FIG. 5 (c) is an enlarged view of the engaging portion of FIG. 5 (a).
[0029]
With respect to the structure of the battery element having the holding means shown in FIG. 5, the battery element 1 is held by using two plate members 2 which are one of the holding means, and the other flat member is used as the plate member connecting means. 5) The plate member 2b has a total of six hook-shaped projections 4 provided at the front end portions on both sides as viewed in the cross-sectional view of FIG. 5 (b). Is inserted into and engaged with a total of six holes 5b provided on both side surfaces. Thus, the positions of the hook-shaped projections and the holes are determined so that pressure is applied to the sandwiched battery element 1.
[0030]
In FIGS. 4 and 5, as described above, the protrusions are inserted into the holes at two locations on both side surfaces of the plate material, and are hooked and fixed.
[0031]
At this time, the plate material, which is one of the clamping means, may be a current collector of each electrode or a terminal, but as shown in each embodiment of FIGS. When a plate material is used separately from the electric conductors and terminals, at least the side surfaces of the plate material (portions that may come into contact with the electrodes of the battery element; including the engaging portion or the engaging means) are made of plastic to prevent short circuit due to conduction. Or a metal with an insulating coating.
[0032]
Further, as shown in each embodiment of FIGS. 2, 4, and 5, the plate material inside the hook-shaped protrusion (the place in contact with the electrode; see the plate material shown by a dashed line in FIGS. 2B and 3B). ) May be curved inward (may be curved in a concave shape). Further, in order to uniformly apply pressure to the electrode, one or more flat plate-like members (spacers) or the above-described plate material may be further sandwiched between the plate material and the electrode as another kind of clamping means ( See FIG. 7).
[0033]
Further, there is a space between the battery element and the exterior material of the polymer / metal composite film on the side of the battery element, and the gas is stored there. Therefore, expansion of the battery at the time of gas generation can be reduced. The space is formed by expansion when gas is generated. Since the inside of the exterior material is depressurized at the stage of battery production, the space is in a shrunken state.
[0034]
Further, as described in claim 4, the holding means is formed by bending and engaging one plate material. As an example, FIG. 3A is a perspective view schematically showing a state immediately before the battery element is bent and bent so that the battery element is provided with the holding means, and FIG. 3) is a cross-sectional view taken along the line AA in FIG. 3 (a), and FIG. 3 (c) shows one sheet material after the battery element of FIG. It is an enlarged view of the said hooked part bent and hooked.
[0035]
The structure of the battery element provided with the holding means shown in FIG. 3 includes a leaf spring which acts on one sheet material 2 which is one of the holding means for holding the battery element 1 in a direction in which the plate element 2 opens under no load. 3 (see FIG. 3B), and three holes having three hook-shaped protrusions 4 provided at one end of the bent plate 2 at the other end of the plate 2 It is inserted into the part 5 and hooked. Since the bent plate member 2 is a plate spring and has a structure in which the battery elements are sandwiched and pressure is applied, the adhesion between the battery elements can be improved. In this embodiment, as shown in FIG. 3 (B), the plate spring is bent so as to be a leaf spring on which a resilient force acts in the direction of opening in a no-load state. A bent plate material may be used so as to be a leaf spring on which an elastic force acts. Also in this case, similarly, since the structure is such that pressure is applied to the battery elements 1, the adhesion between the battery elements can be improved.
[0036]
Further, as shown in FIG. 3B, also in this embodiment, there is a space between the side of the battery element and the bent portion of the plate material (exterior material of the polymer-metal composite film), and the gas accumulates there. Therefore, the expansion of the battery can be reduced even when gas is generated.
[0037]
At this time, the plate material, which is one of the sandwiching means, may be a current collector of each electrode or a terminal, but as shown in the embodiment of FIG. If a plate is used separately, at least the side surfaces of the plate (portions that may come in contact with the electrodes of the battery element; including the hooks or hooking means) should be made of plastic or insulating coating to prevent short circuit due to conduction. Metal must be used.
[0038]
The plate in contact with the electrodes may be curved inward (may be curved in a concave shape; see the plate indicated by the dashed line in FIG. 2 (b)). Further, in order to uniformly apply pressure to the electrode, one or more flat plate-like members (spacers) or another plate material may be further sandwiched between the plate material and the electrode as another kind of holding means. Further, there is a space on the side of the battery element between the battery and the exterior material of the polymer-metal composite film, and the gas is stored there.
[0039]
Further, as described in claim 5, the engaging portion may be further fixed by welding or welding. By doing so, the adhesion of the battery element can be further improved and the expansion of the battery can be prevented. In addition, there is no danger that the engagement portion will be disengaged and the adhesion of the battery element will be reduced, as in the case of a vehicle battery, and long-term safety and reliability can be improved. For example, the above-described engaging portion in FIGS. 2 to 5, that is, the hook-shaped protrusion may be inserted into the hole, and the periphery of the portion where the hook-shaped protrusion protrudes from the hole may be fixed by welding or welding. . In particular, since welding or welding is performed after the battery element is sandwiched, it can be said that ultrasonic welding or the like that generates as little heat as possible is desirable.
[0040]
Further, as described in claim 6, the coupling means overlaps the projection provided on at least one plate material with the projection provided on the other at least one plate material, and welds or welds the overlapped portion. It may be fixed.
[0041]
FIG. 6A is a perspective view showing a structure of a battery element including the holding means of the first embodiment, and FIG. 6B is a view taken along line AA of FIG. FIG. 6 (c) is an enlarged view of the engaging portion of FIG. 6 (a).
[0042]
As for the structure of the battery element provided with the holding means of FIG. 6, the battery element 1 is held by using two plate members 2 which are one of the holding means, and one of the plate members 2a is provided as a plate member connecting means. The two projections 4a, 4b and the two projections 4c, 4d of the other plate 2b are overlapped, respectively, and the two overlapped portions are welded and fixed. The welded portion 6 formed by welding two plate members may be the entire overlapping portion of the two plate members. However, as shown in FIG. 6A and FIG. The adhesiveness between them can be improved, and a bonding force that does not come off even when the battery expands when gas is generated can be achieved.
[0043]
More specifically, one plate 2a having a mountain-shaped cross section as viewed in the cross-sectional view of FIG. 6B is a plate material coupling means, and the other plate 2b having a mountain-shaped cross section is a protrusion 4a, 4b at the tip of both sides. The protrusions 4c and 4d at the same both side end portions are overlapped respectively, and the two overlapped portions of the protrusions 4a and 4c and 4b and 4d are respectively welded and fixed by ultrasonic welding or the like. . That is, the embodiment shown in FIG. 6 has a structure of welding and fixing at two places.
[0044]
FIG. 7A is a perspective view showing a structure of a battery element including the holding means of the second embodiment, and FIG. 7B is a view taken along a line AA in FIG. FIG. 7 (c) is an enlarged view of the engaging portion of FIG. 7 (a).
[0045]
That is, as for the structure of the battery element provided with the holding means of FIG. 7, the battery element 1 is held by using two plate members 2 which are one of the holding means, and one of the plate members 2a is used as the plate member connecting means. And the two projections 4c and 4d of the other plate member 2b are overlapped, respectively, and the two overlapped portions are welded and fixed. The welded portion 6 formed by welding two plate members may be the entire surface of the overlapped portion of the two plate members. However, as shown in FIGS. The adhesiveness between them can be improved, and a bonding force that does not come off even when the battery expands when gas is generated can be achieved.
[0046]
Further, in FIG. 7, flat plates 2c and 2d were inserted between the electrodes of the battery element 1 and the plates 2a and 2b of the holding means, respectively, so that the pressure was uniformly applied to the battery. Structure.
[0047]
At this time, the plate material, which is one type of the holding means, may be a current collector for each electrode or a terminal, but as shown in each embodiment of FIGS. If a plate material is used separately from the terminals and terminals, at least the side surfaces of the plate material (portions that may come into contact with the electrodes of the battery element; It must be an insulator such as a metal coated with insulation.
[0048]
Further, the plate members 2a and 2b inside the protrusions (locations in contact with the electrodes; see the plate members indicated by the dashed lines in FIGS. 2B and 3B) may be curved inward ( It may be warped in a concave shape). In order to uniformly apply pressure to the electrodes, one or more flat plate-like members (spacers) 2c and 2d may be interposed between the plate material and the electrodes as another type of the holding means ( See FIG. 7).
[0049]
Further, there is a space between the battery element and the exterior material of the polymer / metal composite film on the side of the battery element, and the gas is stored there. Therefore, expansion of the battery at the time of gas generation can be reduced. The space is formed by expansion when gas is generated. Since the inside of the exterior material is depressurized at the stage of battery production, the space is in a shrunken state.
[0050]
According to the first aspect of the present invention, and more particularly, the second aspect of the present invention has a structure as shown in FIGS. 1 to 7, thereby improving the adhesion of the battery elements and preventing the output from decreasing. In addition, even when gas is generated, the expansion of the battery element and the battery can be reduced, the cycle characteristics can be improved, the deterioration of the battery can be promoted, and the output can be prevented from lowering. Further, a space is provided on the side of the battery element between the battery element holding means and a gas reservoir to prevent gas from remaining between the battery elements.
[0051]
Further, as described in claim 7, the plate members forming the holding means are a positive electrode current collector, a negative electrode current collector and / or a positive electrode terminal and a negative electrode terminal, respectively. As an example, FIG. 8A is a cross-sectional view taken along line AA of FIG. 1A when the plate material is a terminal, and FIG. 8A is an enlarged view showing a state of a contact portion between the terminal and the battery element on the positive electrode terminal side of the plate material of FIG. 8A, and FIG. 8C shows a case where the plate material is a current collector. FIG. 8D is a cross-sectional view taken along the line AA of FIG. 8A, and FIG. 8D shows a state of a contact portion between the current collector and the battery element on the positive electrode current collector side of the plate material of FIG. FIG.
[0052]
In FIG. 8A, the plate 2a is used as a positive terminal, and the plate 2b is used as a negative terminal, out of the two plates forming the holding means. Therefore, as shown in FIG. 8B, the positive electrode terminal of the battery element is in contact with the positive electrode terminal, which is a plate member, so as to be electrically connected thereto. A positive electrode (active material) is formed only on the lower surface side of the positive electrode current collector. The battery element 1 does not include the terminal that is the plate material.
[0053]
On the other hand, in FIG. 8C, the plate 2a is used as a positive electrode current collector, and the plate 2b is used as a negative electrode current collector among the two plates forming the holding means. Therefore, as shown in FIG. 8D, the positive electrode (active material) is in contact with the positive electrode current collector as the plate material. The battery element 1 includes a current collector that is the plate material. However, it can be said that the battery element holding means defined in claim 1 of the present invention may use a part of the battery element. Further, in the description of the embodiments of claims 2 to 6, the current collector is not used for the plate material, so that the battery element is sandwiched between two plate materials. However, when the current collector is used for the plate material, It can be said that the battery element (excluding the current collector, which is a plate material) may be sandwiched between the two plate materials.
[0054]
By adopting such a structure, the plate material, which is one of the battery element holding means, and the positive electrode and the negative electrode terminal can be shared, the device can be made compact, the connection between the current collector and the terminal becomes unnecessary, the resistance can be reduced, and The output is obtained.
[0055]
The outer shape of the secondary battery used in the present invention is preferably as described in claim 8. As an example, FIG. 9A is a perspective view schematically showing a battery in which a wide electrode terminal is projected from a battery exterior, and FIG. 9B is a perspective view of FIG. 9A. It is sectional drawing along the AA line.
[0056]
As shown in FIG. 9A, a secondary battery 11 is a secondary battery in which a battery element 1 is externally covered with a polymer-metal composite film 12, and the battery element 1 is sandwiched and held as battery element sandwiching means. And two plates 2a and 2b fixed by means, and the positive electrode 16 and the negative electrode 17 for taking out current are located on different surfaces (sides) of (a secondary battery of) a substantially rectangular shape. The wide current extraction electrode terminals 13 and 14 attached to the positive electrode current collector and the negative electrode current collector 19 inside the battery exterior are made to protrude directly from the thermo-thermally fused portion 15 of the battery exterior.
[0057]
More specifically, the polymer-metal composite film 12 of the battery exterior is joined by heat fusion at its peripheral portion, thereby housing and enclosing a battery element (not shown) including the battery element holding means. ing. The positive electrode terminal 13 and the negative electrode terminal 14 have a structure in which they are taken out from the heat-sealed portions 15 on substantially square different surfaces (different sides; opposite sides) of the exterior laminate film 12.
[0058]
As shown in FIG. 9 (b), this secondary battery 11 is provided with two plate members 2a and 2b which hold the battery element 1 as a battery element holding means and are fixed by coupling means. The positive electrode 16 and the negative electrode 17 for taking out a current are located on different surfaces (sides) of (a secondary battery of) a substantially rectangular shape (secondary battery), and a positive electrode current collector (FIG. (Not shown) and a wide positive electrode terminal (not shown) and a negative electrode terminal 14 attached to the negative electrode current collector 19 are made to protrude directly from the polymer-metal composite film 12 of the battery exterior. Specifically, the battery 11 includes a battery element 1 in which a positive electrode 16, a separator 18 and a negative electrode 17 are laminated by using a laminate film 12 on the exterior and joining the entire periphery thereof by heat fusion. 1 is sandwiched and fixed with the plate members 2a and 2b, and is sealed. A positive electrode terminal (not shown) and a negative electrode terminal 14 that are electrically connected to the positive electrode 16 and the negative electrode 18 are connected to the positive electrode current collector (not shown) and the negative electrode current collector 17 of each of the electrodes 16 and 18 by ultrasonic welding and resistance welding. It has a structure in which the wide electrode terminals 13 and 14 sandwiched between the heat-sealed portions 15 are directly taken out of the laminate film 12 of the exterior.
[0059]
With such a structure, the electrode terminals can be widened, and an effect that parallel connection of such secondary batteries becomes easy can be obtained.
[0060]
It is preferable that the secondary battery used in the present invention is an assembled battery having a connection state as described in claim 9. One example is shown in FIG.
[0061]
FIG. 10 is a plan view schematically illustrating a battery group in which secondary batteries are electrically connected in parallel, and an internal configuration of a battery pack in which electrical connections are further electrically connected in series.
[0062]
As shown in FIG. 10, a specific example of the structure of an assembled battery in which a battery group in which secondary batteries are electrically connected in parallel is further electrically connected in series is shown.
[0063]
As shown in FIG. 10, between the positive terminals 13 and between the negative terminals 14 of the four secondary batteries 12 are connected in parallel. The battery packs obtained in this way are further connected in series in six sets and housed in a metal battery pack case 22 to form a battery pack 21. In addition, the positive electrode terminal 23 and the negative electrode terminal 24 of the assembled battery 21 provided in the assembled battery case 22 and the electrode terminals 13 and 14 of each secondary battery 12 are the lead wires for the positive electrode and the negative electrode terminal of the assembled battery 21 (see FIG. (Not shown). When connecting four rechargeable batteries 12 in parallel, the electrode terminals of the rechargeable batteries 12 are welded by ultrasonic welding or the like using an appropriate connection member (not shown) such as a spacer. What is necessary is just to electrically connect by welding. Similarly, when further connecting six sets of each battery group in series, the electrode terminals 13 and 14 of each secondary battery 12 are ultrasonically welded using an appropriate connection member (not shown) such as a bus bar. May be electrically connected by welding or welding. However, the battery pack of the present invention should not be limited to the battery described here, and a conventionally known battery can be appropriately used. The assembled battery may be provided with various measuring devices and control devices according to the intended use. For example, the assembled battery case 22 is provided with a voltage measurement connector or the like for monitoring the battery voltage. It is not particularly limited.
[0064]
By adopting such a structure, it is possible to obtain the effect of being able to cope with various variations of output by changing the number of series and parallel assembled batteries.
[0065]
The secondary battery used in the present invention is desirably a composite battery having a connection state as described in claim 10. One example is shown in FIG.
[0066]
FIG. 11 is a schematic perspective view schematically showing a composite battery pack in which at least two or more of the above battery packs are connected in series, in parallel, or in series and in parallel.
[0067]
As shown in FIG. 11, in order to connect the six assembled batteries 21 (see FIG. 10) in parallel to form a composite assembled battery 31, the positive terminal of the assembled battery provided in each assembled battery case 21 23 and the negative electrode terminal 24 are electrically connected using an assembled battery positive terminal connecting plate 34 and an assembled battery negative terminal connecting plate 35 having an external positive terminal 32 and an external negative terminal 33, respectively. A connection plate 36 having an opening corresponding to the fixing screw hole is fixed to each screw hole (not shown) provided on both side surfaces of each battery pack case 22 with a fixing screw 37. The batteries 21 are connected to each other. In addition, the positive electrode terminal 23 and the negative electrode terminal 24 of each battery pack 21 are protected by a positive electrode insulating cover 38 and a negative electrode insulating cover 39, respectively, and are identified by being classified into appropriate colors, for example, red and blue.
[0068]
By adopting such a structure, when mounted on an electric vehicle or hybrid car, it is possible to respond to the demand for battery capacity and output for each purpose of use relatively inexpensively without making a new assembled battery become. Further, by setting the assembled battery module to a high voltage, it can be used for vehicles such as electric vehicles and hybrid cars.
[0069]
The secondary battery, the assembled battery, and / or the composite assembled battery used in the present invention can be suitably used for vehicle applications. One example is shown in FIG.
[0070]
FIG. 12 is a schematic diagram schematically showing a vehicle equipped with the secondary battery, the assembled battery, and / or the composite assembled battery.
[0071]
As shown in FIG. 12, it is convenient to mount the battery pack 31 under the seat in the center of the vehicle body of the EV, HEV or FCV 41 because the office space and the trunk room can be widened. However, the present invention is not limited to these, and may be mounted in the lower part of the rear trunk room, or if the engine is not mounted such as EV or FCV, the engine in front of the vehicle body is mounted. It can also be mounted on parts that were used. In the present invention, not only the composite battery, but also a secondary battery or a battery pack may be mounted depending on the intended use, or the secondary battery, the battery pack, and / or the composite battery pack may be appropriately mounted. You may make it mount in combination. Further, as the vehicle on which the secondary battery, the assembled battery, and / or the composite assembled battery of the present invention can be mounted, the above-described EV, HEV, and FCV are preferable, but not limited thereto.
[0072]
According to the eleventh aspect of the present invention, by using a high-output battery module, it is possible to obtain an effect that an eco-friendly vehicle with good fuel efficiency can be provided. In addition, with such a structure, a relatively inexpensive, high-energy-density, high-output battery pack can be manufactured, and an EV, HEV, or FCV with a long cruising distance and high fuel efficiency can be provided. In addition, by mounting the secondary battery, the assembled battery, and / or the composite assembled battery on a vehicle such as an EV, an HEV, and an FCV, it is possible to suppress heat generation of the electrode terminal leads at the time of large current discharge at the time of mounting, thereby improving the life characteristics. In addition, it is possible to solve the above-mentioned problem of securing good sealing performance over a relatively long period.
[0073]
Next, when a lithium ion secondary battery is applied to the structure of the present invention, the following lithium ion secondary batteries are desirable.
[0074]
(1) A lithium ion secondary battery using at least one of a lithium transition metal oxide, a metal oxide, a metal sulfide, a conductive polymer, and an organic sulfur compound as a positive electrode active material.
[0075]
(2) For the positive electrode active material, use at least one of lithium manganese oxide, lithium nickel oxide, lithium cobalt oxide, lithium iron oxide, and oxides obtained by substituting some of these elements with other elements. A lithium ion secondary battery characterized by being used.
[0076]
(3) A lithium ion secondary battery characterized in that the average particle size of the positive electrode active material is 30 μm or less. In order to increase the output as a vehicle battery, it is desirable that the average particle diameter is in the above range.
[0077]
(4) A lithium ion secondary battery, wherein the filling rate (mass ratio) of the positive electrode active material in the positive electrode material is in the range of 0.3 to 0.7. Such a filling ratio range is desirable in terms of optimizing high power and energy capacity. In addition, in addition to the positive electrode active material, if necessary, a binder and a conductive auxiliary agent are added to the positive electrode material here (however, the current collector is not included). It is not limited, and it can be said that an optimum cathode material may be determined according to the purpose of use.
[0078]
(5) A lithium ion secondary battery, wherein the thickness of the positive electrode active material layer is in the range of 10 to 200 μm. Such a range of the film thickness is desirable from the viewpoint of optimizing high output, particularly high output and energy capacity required for a vehicle such as an automobile. Here, the film thickness refers to the film thickness on one side of the positive electrode active material layers formed on both surfaces of the positive electrode current collector.
[0079]
(6) A lithium ion secondary battery characterized in that at least one of a carbon material, an alloy, an oxide, and a nitride capable of inserting and removing lithium is used as a negative electrode active material.
[0080]
(7) A lithium ion secondary battery using at least one of graphitized carbon fiber and amorphous carbon as a negative electrode active material.
[0081]
(8) The specific surface area of the negative electrode active material is 0.05 to 5 m ² / G or less. From the viewpoint of optimizing high output and capacity as a battery for a vehicle, such a range of the specific surface area is desirable.
[0082]
(9) A lithium ion secondary battery, wherein the thickness of the negative electrode active material layer is in the range of 10 to 250 μm. Such a range of the film thickness is desirable from the viewpoint of optimizing the high output and the energy capacity. Here, the film thickness refers to the film thickness on one side of the negative electrode active material layers formed on both surfaces of the negative electrode current collector.
[0083]
Still more preferable combinations of the positive electrode material and the negative electrode material include a combination using a LiMn composite oxide, a LiNi composite oxide, or a mixture thereof for the positive electrode material and using an amorphous carbon material for the negative electrode material. . The reasons are as follows. In order to use a battery having a small capacity per unit for an automobile, it is necessary to connect them in parallel. However, there is a case where a difference occurs in the charge / discharge state between the batteries during use and the open-circuit voltage differs. At this time, the function of automatically adjusting the discharging state (charging state) to the same level so that the open-circuit voltages of the batteries connected in parallel originally becomes substantially the same. However, for example, when a Ni-H based battery having a small slope of the open voltage with respect to the discharge state (charge state) in the charge / discharge characteristic curve is used, no difference appears in the open voltage even if the discharge states (charge states) are different from each other. Does not work, and if charging and discharging are continued as it is, overcharging and overdischarging may occur, which may promote deterioration of the battery material.
[0084]
(10) LiPF as electrolyte ₆ , LiBF ₄ , LiClO ₄ , LiAsF6, LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ Inorganic acid anion salts such as Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ Cyclic carbonates such as propylene carbonate, ethylene carbonate and the like containing at least one lithium salt selected from organic acid anion salts such as N; chain carbonates such as dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate; Ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane; lactones such as γ-butyrolactone; nitriles such as acetonitrile; methyl propionate and the like Amides such as dimethylformamide; and a lithium ion secondary battery using an aprotic solvent in which at least one or more selected from methyl acetate and methyl formate are mixed. It is.
[0085]
(11) The lithium ion secondary battery is characterized in that the battery separator is a polyolefin-based microporous separator, for example, polyethylene, polypropylene, or a multi-layered body obtained by combining two or more layers thereof. The polyolefin-based microporous separator having the property of being chemically stable to an organic solvent has an excellent effect that the reactivity with an electrolyte (electrolyte solution) can be suppressed to a low level.
[0086]
(12) A lithium ion secondary battery characterized in that the thickness of the battery separator is 4 to 60 μm in a single layer or a multilayer. When the thickness of the separator is within the above range, it is desirable to prevent short-circuiting caused by fine particles digging into the separator and to narrow the gap between the electrodes for high output. This has the effect of ensuring high output power. In the case where a plurality of batteries are connected, the electrode area increases, so that it is desirable to use a thick separator in the above range in order to enhance the reliability of the batteries.
[0087]
(13) A lithium ion secondary battery characterized in that the diameter of the micropores of the battery separator is at most 1 μm or less. When the average diameter of the micropores in the separator is in the above range, the separator is melted by heat and the "shutdown phenomenon" in which the micropores close rapidly occurs. There is an effect that is improved. In other words, when the battery temperature rises due to overcharging (in the event of an abnormality), the "shutdown phenomenon" in which the separator melts and the micropores close, which occurs quickly, causes the battery (electrode) to move from the positive electrode (+) Li ions cannot pass through to the negative electrode (-) side, and cannot be charged any more. Therefore, overcharging cannot be performed, and overcharging is eliminated. As a result, the heat resistance (safety) of the battery can be improved, and gas can be prevented from being opened to open the heat-sealed portion (seal portion) of the battery exterior material. Here, the average diameter of the micropores of the separator is calculated as an average diameter obtained by observing the separator with a scanning electron microscope or the like and statistically processing a photograph thereof with an image analyzer or the like.
[0088]
(14) A lithium ion secondary battery, wherein the porosity of the battery separator is 20 to 50%. When the porosity of the separator is within the above range, the output and reliability are reduced because the output is prevented from decreasing due to the resistance of the electrolyte (electrolyte solution) and the short circuit is prevented due to the fine particles penetrating through the pores (micropores). It has the effect of ensuring both sexes. Here, the porosity of the separator is a value obtained as a volume ratio from the density of the raw material resin and the density of the separator of the final product.
[0089]
(15) A lithium ion secondary battery characterized in that the slope of the open-circuit voltage with respect to the discharge state (charge state) is in the range of 2 to 20 mV /% when the SOC (state of charge) is 50%. . Such a range of the slope of the open-circuit voltage is desirable from the viewpoint of easily performing the capacity calculation and providing characteristics that can withstand the voltage fluctuation of the system as a vehicle-mounted battery.
[0090]
(16) When the battery shape is a rectangular parallelepiped and the battery has a width W, a length L, and a thickness H, the W / L ratio is in the range of 0.3 to 1.0 and the W / H ratio is 5 to 100. The lithium ion secondary battery is characterized by being within the range. From the viewpoint of the heat dissipation of the battery, the ranges of the W / L ratio and the W / H ratio are desirable. Here, the width W, length L, and thickness H of the lithium ion secondary battery are as shown in FIG.
[0091]
(17) A lithium ion, wherein the battery has a rectangular parallelepiped shape, and has a width W of 50 to 200 mm, a length L of 50 to 300 mm, and a thickness H of 2 to 10 mm. It is a secondary battery. Such a shape and dimensions are desirable from the viewpoint of ease of taking out a wide battery terminal having excellent terminal heat dissipation and the heat dissipation of the battery.
[0092]
(18) The lithium ion secondary battery, wherein the width Wa of each battery terminal taken out from the battery exterior film is 20 to 90% of the length of one side of the exterior film taken out (battery width W). Battery. Here, the width Wa of the battery terminal and the length of one side of the exterior film to be taken out (the width W of the battery) are as shown in FIG. 9A. Such terminals and exterior film dimensions are desirable in that good sealing properties can be ensured and the temperature rise of the electrode terminals can be suppressed to 30 ° C. or less. By suppressing the temperature rise of the electrode terminal to 30 ° C. or less, it is possible to suppress the deterioration of the sealing property of the heat-sealed portion of the exterior film particularly in contact with the electrode terminal due to the increase of the internal pressure of the battery. is there. Furthermore, since the positive electrode and the negative electrode can be taken out from different surfaces (for example, opposite sides), the terminal width can be widened, and high output for automobiles and the like can be handled. Here, high output means that a current of about 30 C (30 A for a battery with a capacity of 1 Ah) flows. The electrode width is preferably 20 to 90% of the battery width for the same reason.
[0093]
(19) At least one method such as ultrasonic welding, heat welding, laser welding, rivet, caulking, and electron beam is used as a connection method when connecting cells (lithium ion secondary batteries) in parallel or in series. It is a battery pack of a lithium ion secondary battery characterized by the above-mentioned.
[0094]
The lithium ion secondary batteries of the above (1) to (19) and the assembled battery thereof have the following effects.
[0095]
-When connecting single cells (lithium ion secondary batteries) in parallel, if the slope of the open circuit voltage is small, connection can be made even if there is a difference in SOC, and if charging and discharging are repeated, overcharging and overdischarging may occur. There is. If there is a slope of the open circuit voltage, they can be prevented.
[0096]
-Heat dissipation is improved, heat does not accumulate in the battery element portion, and deterioration is not promoted.
[0097]
・ By increasing the width of the battery and the width of the battery terminals, a large current discharge is possible. This is particularly effective as a vehicle battery.
[0098]
・ Easy when connecting single cells (lithium ion secondary batteries) in parallel and in series.
[0099]
-If one battery pack fails, one of the batteries may be replaced. This is because when the battery pack is mounted on a vehicle, a composite battery pack in which battery packs are further connected in series, in parallel, or in series-parallel is used, but the battery packs can be connected in a replaceable manner.
[0100]
The batteries shown in the respective drawings are batteries having the following specifications.
[0101]
After covering with a polymer-metal composite film, each electrode terminal was taken out, an electrolytic solution was injected while being evacuated, and then a hole for injecting the electrolytic solution was closed.
[0102]
LiMn ₂ O ₄ System lithium ion secondary battery is used, and the active material of the positive electrode material is LiMn ₂ O ₄ However, it may be a Li-deficient type or a Li-excess type. Further, a part of Mn may be replaced by a metal element composed of at least one selected from transition metal elements other than Mn and other metal elements. Further, it may be an O-deficient type or an O-excess type. Further, a part of O may be replaced by at least one element selected from elements such as S, F, and Cl. Also, LiNiO ₂ And its substitute, LiFeO ₂ And its substitute, LiMnO ₂ And its substitutes.
[0103]
As the negative electrode, any of the materials used for ordinary non-aqueous electrolyte secondary batteries can be used. For example, lithium-based metals such as metallic lithium and lithium alloy, SnSiO ₃ Metal oxides such as LiCoN ₂ Metal nitrides and carbon materials. In the present invention, carbon materials such as coke, natural graphite, artificial graphite, and non-graphitizable carbon can be suitably used.
[0104]
As the electrolytic solution, a solution prepared by dissolving various lithium salts as an electrolyte in a non-aqueous solvent such as an organic solvent can be used. In this case, LiClO is used as the electrolyte. ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₆ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ Conventionally known materials such as N are exemplified. In addition, examples of the organic solvent include, but are not particularly limited to, carbonates, lactones, and ethers, and include, for example, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, Solvents such as 1,2-diethoxyethane, tetrahydrofuran, 1,3-dioxolan, and γ-butyrolactone can be used alone or in combination of two or more. The concentration of the electrolyte dissolved in these non-aqueous solvents and organic solvents is preferably 0.5 to 2.0 mol / L. By setting the concentration in such a range, the ionic conductivity of the electrolytic solution is improved, and the output can be further increased.
[0105]
Further, in the lithium secondary battery of the present invention, it is also possible to use an electrolytic medium other than the electrolytic solution, for example, a solid or viscous body in which the electrolyte is uniformly dispersed in a polymer matrix, or Can also be used. In this case, as the polymer matrix, for example, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride and the like can be used.
[0106]
Furthermore, in the lithium secondary battery of the present invention, a separator for preventing a short circuit between the positive electrode and the negative electrode can be provided. As such a separator, a porous sheet of a polymer material such as polyethylene and cellulose, or a nonwoven fabric is used.
[0107]
The polymer-metal composite laminate film of the lithium secondary battery of the present invention is not particularly limited, and a conventionally known film obtained by disposing a metal film between polymer films and laminating and integrating the whole is used. can do. As a specific example, for example, it is arranged as an exterior protective layer (outermost layer of a laminate) made of a polymer film, a metal film layer, and a heat fusion layer (innermost layer of a laminate) made of a polymer film, and the whole is laminated and integrated. But should not be limited to these.
[0108]
【The invention's effect】
In the secondary battery of the present invention, by providing the battery element holding means, the adhesion between the battery elements can be improved, the expansion of the battery can be reduced even when gas is generated, and good cycle characteristics and output can be obtained. .
[Brief description of the drawings]
FIG. 1 (a) is a perspective view showing a structure of a battery element including two plate members and a sandwiching means composed of the plate member coupling means, and FIG. 1 (b) is a perspective view showing the structure of the two battery members. It is a front view showing the structure of the battery element provided with the board material and the holding means which consists of this board material coupling means.
FIG. 2 (a) is a perspective view showing a structure of a battery element including the holding means of the first embodiment, and FIG. 2 (b) is a sectional view taken on line A- of FIG. 2 (a). FIG. 2C is a cross-sectional view taken along the line A, FIG. 2C is a front view of FIG. 2A, and FIG. 2D is an enlarged view of a hooked portion of FIG. .
FIG. 3 (a) is a perspective view schematically showing a state immediately before a single plate is bent and engaged with a battery element so as to include a holding means, and FIG. 3 (b). FIG. 3A is a cross-sectional view taken along the line AA in FIG. 3A, and FIG. 3C is a diagram illustrating a state in which one sheet material is bent after the battery element of FIG. It is an enlarged view of the engaging part which is engaged.
FIG. 4 (a) is a perspective view showing a structure of a battery element provided with the holding means of the second embodiment, and FIG. 4 (b) is a sectional view taken on line A- of FIG. 4 (a). FIG. 4C is a cross-sectional view taken along a line A, and FIG. 4C is an enlarged view of a hooked portion in FIG.
FIG. 5 (a) is a perspective view showing the structure of a battery element provided with the holding means of the third embodiment, and FIG. 5 (b) is a perspective view of A- in FIG. 5 (a). FIG. 5C is a cross-sectional view taken along the line A, and FIG. 5C is an enlarged view of a hooked portion in FIG.
FIG. 6 (a) is a perspective view showing the structure of a battery element provided with the holding means of the first embodiment, and FIG. 6 (b) is a sectional view taken on line A- of FIG. 6 (a). FIG. 6C is a cross-sectional view along the line A, and FIG. 6C is an enlarged view of a hooked portion in FIG.
FIG. 7A is a perspective view showing a structure of a battery element including the holding means of the second embodiment, and FIG. 7B is a perspective view of FIG. FIG. 7C is a cross-sectional view along the line A, and FIG. 7C is an enlarged view of a hooked portion in FIG.
FIG. 8A is a cross-sectional view taken along line AA of FIG. 1A when the plate is a terminal, and FIG. 8B is a cross-sectional view of the plate of FIG. 8A. FIG. 8C is an enlarged view showing a state of a contact portion between the terminal and the battery element on the positive electrode terminal side, and FIG. 8C is a line AA in FIG. 1A when the plate material is a current collector. 8D is an enlarged view showing a state of a contact portion between the current collector and the battery element on the positive electrode current collector side of the plate member of FIG. 8C. .
FIG. 9A is a perspective view schematically showing a battery in which a wide electrode terminal is projected from a battery exterior, and FIG. 9B is a perspective view of A in FIG. 9A. It is sectional drawing along the -A line.
FIG. 10 is a plan view schematically illustrating a battery group in which secondary batteries are electrically connected in parallel, and an internal configuration of a battery pack in which electrical connections are further electrically connected in series.
FIG. 11 is a schematic perspective view schematically showing a composite battery pack characterized in that at least two or more of the above battery packs are connected in series, in parallel, or in series and in parallel.
FIG. 12 is a schematic view schematically showing a vehicle equipped with the secondary battery, the assembled battery, and / or the composite assembled battery.
[Explanation of symbols]
1: battery element 2, 2a-2d: plate material,
3 tape, 4 protrusions,
4a: hook portion, 5, 5a, 5b: hole portion,
6 ... weld, 11 ... rechargeable battery,
12. Battery exterior material (polymer-metal composite laminate film),
13 ... a positive electrode terminal of a secondary battery; 14 ... a negative electrode terminal of a secondary battery;
15: heat-sealed part, 16: positive electrode,
17 ... negative electrode, 18 ... separator,
19: negative electrode current collector, 21: assembled battery,
22: assembled battery case, 23: positive terminal of assembled battery,
24 ... negative terminal of assembled battery 31 ... combined assembled battery
32 ... external positive terminal part 33 ... external negative terminal part
34 ... battery assembly positive terminal connection plate 35 ... battery assembly negative terminal connection plate
36 ... connecting plate, 37 ... fixing screw,
38: Positive insulating cover, 39: Negative insulating cover,
41: EV, HEV or FCV.

Claims (11)

A secondary battery having a battery element packaged with a polymer-metal composite laminate film, comprising a battery element holding means. 2. The secondary battery according to claim 1, wherein the holding unit includes two or more plate members and the plate member connecting unit. 3. The secondary battery according to claim 2, wherein the coupling unit engages a protrusion provided on one of the at least one plate with a hole provided on the other at least one plate. 2. The secondary battery according to claim 1, wherein the holding unit is formed by bending and engaging a single plate. 3. The secondary battery according to any one of claims 1 to 4, wherein the engaging portion is further welded, welded, or fixed. The said joining means overlaps the projection part which one at least one plate material has, and the projection part which the other at least one plate material has, and welds or welds and fixes the overlapped part. 3. The secondary battery according to 2. 4. The secondary battery according to claim 2, wherein the plate members forming the holding means are a positive electrode current collector, a negative electrode current collector, and / or a positive electrode terminal and a negative electrode terminal, respectively. 5. The electrode for current extraction is located on a different surface of a substantially square shape, and the electrode terminal for wide current extraction attached to the current collector inside the laminated electrode current collector or battery exterior is directly connected to the battery exterior. The secondary battery according to any one of claims 1 to 7, wherein the secondary battery is protruded. An assembled battery, wherein a battery group in which the secondary batteries according to claim 1 are electrically connected in parallel is further electrically connected in series. A composite battery module comprising at least two or more of the battery modules according to claim 9 connected in series, in parallel, or in series and in parallel. A vehicle equipped with the secondary battery, the assembled battery, and / or the composite assembled battery according to any one of claims 1 to 10.

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