JP2008016202A - Battery module of laminate-armored flat battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery module of a laminate-armored flat battery with good electric jointing of the laminate-armored flat batteries themselves and with excellent battery characteristics. <P>SOLUTION: In a battery module made by connecting in series at least two or more laminate-armored flat batteries each equipped with a laminated electrode group made by plurally laminating a sheet-shape cathode and a sheet-shape anode through a separator in a laminate-armored body and equipped with a cathode terminal lead and an anode terminal lead protruded in the same direction outside the laminate-armored body, connection of the batteries is made by a connection conductor arranged between the cathode terminal lead of one of the batteries and the anode terminal lead of the other battery, with one end of the connection conductor welded to the cathode terminal lead of one of the batteries and the other end thereof welded to the anode terminal lead of the other battery. The connection conductor is provided with shock-absorbing part with the side face shape in a length direction in a wave shape. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery module of a laminate-clad flat battery, and more particularly to a battery module of a laminate-clad flat battery that is expected to have long-term reliability against vibration and dropping.

  In recent years, electric bicycles and electric vehicles that use electricity as a power source have attracted attention, and the development of batteries with high energy density and high output density mounted on them occupies an important industrial position. As a battery structure for such a use, a wound power generation element is housed in a cylindrical case, a wound power generation element, or a power generation element in which flat electrodes and separators are laminated is a flat case. There is something stored in.

  Since these cylindrical or flat cases need to have strength, they must be formed of a metal container, and there is a problem that weight reduction is not easy. Therefore, as a means for reducing the weight of the battery and achieving higher energy density and higher output, for example, Patent Document 1 discloses a battery having a structure in which a laminate film is used as an outer case and its periphery is sealed by thermal fusion. Has been proposed.

  It is also conceivable to apply the laminated outer flat battery as described above as a battery module connected in series and / or in parallel to the above application.

  A laminated outer flat battery usually has a structure in which a positive electrode terminal lead and a negative electrode terminal lead (hereinafter, collectively referred to as “electrode terminal lead”) are drawn out of the laminated outer body. In order to connect a plurality of such batteries into a battery module, for example, a connection conductor is disposed between the positive terminal lead of one battery and the negative terminal lead of another battery, A method in which one end is welded to the positive terminal lead and the other end is welded to the negative terminal lead can be employed. By the above method, a battery module formed by connecting a plurality of batteries in series can be manufactured.

JP 11-224652 A

  In addition, when the battery module is applied to an application such as an electric bicycle or an electric vehicle, the battery module is easily affected by vibration, drop, etc., so that the connection between the batteries is maintained even when the battery module receives such an impact. As described above, the welded portion between the connection conductor and the positive electrode terminal lead / negative electrode terminal lead is required to have sufficient bonding strength.

  However, in a laminated exterior flat battery, the positive electrode terminal lead and the negative electrode terminal lead are generally made of different metals, and therefore, for example, the connection conductor is connected to one electrode terminal lead (for example, the negative electrode terminal lead). When a battery module is formed using a connection conductor made of a material suitable for welding with a), the joint strength of the welded portion with the other electrode terminal lead (for example, the positive terminal lead) may be insufficient. In such a battery module, there is a possibility that peeling or the like may occur in the welded part when subjected to vibration or dropping.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery module for a laminate-clad flat battery that has good electrical connection between laminated-clad flat batteries and has excellent battery characteristics. There is to do.

  The battery module of the laminated exterior flat battery of the present invention that can achieve the above object is a sheet-like positive electrode having a positive electrode mixture layer on at least one surface of a current collector made of aluminum or aluminum alloy, and made of copper or copper alloy. A laminate electrode group in which a plurality of sheet-like negative electrodes each having a negative electrode mixture layer on at least one surface of the current collector are laminated via a separator, and a non-aqueous electrolyte in the laminate outer package, A laminated external flat battery having a positive terminal lead and a negative terminal lead projecting in the same direction outside the exterior body is connected in series with at least two or more, wherein the connection between the batteries is one of One end of the battery is disposed between the positive terminal lead of the battery and the negative terminal lead of the other battery, and one end is melted with the positive terminal lead of the one battery. The other end is made of a connection conductor welded to the negative electrode terminal lead of the other battery, and the connection conductor has a buffer portion whose side surface shape in the length direction is a wave shape. Is.

  ADVANTAGE OF THE INVENTION According to this invention, the battery module of the lamination exterior flat battery which was excellent in the electrical joining of laminated flat batteries and excellent in the battery characteristic can be provided. That is, the battery module of the laminated outer flat battery of the present invention is excellent in long-term reliability and maintains a long battery life even when applied to an application that may be subjected to an impact due to vibration, dropping, etc. it can.

  First, a laminated outer flat battery constituting a battery module of a laminated outer flat battery of the present invention (hereinafter abbreviated as “battery module”) will be described with reference to the drawings. FIG. 1 is an overall perspective view schematically showing an example of a laminated exterior flat battery according to the present invention.

  The laminated exterior flat battery 10 has a cell body 11 and two electrode terminal leads that protrude in the same direction from the cell body 11, that is, the laminate exterior body (that is, project in parallel or substantially parallel from the same side of the exterior body). (Positive electrode terminal lead 12 and negative electrode terminal lead 13). Reference numeral 20 denotes a heat-sealed portion of the laminate outer package.

  The positive terminal lead 12 is made of, for example, aluminum (including an aluminum alloy). The negative electrode terminal lead 13 is made of, for example, copper (including a copper alloy, the same shall apply hereinafter), nickel (including a nickel alloy), or copper having nickel plating or tin plating.

  In FIG. 2, the longitudinal cross-sectional schematic of the principal part of the laminated exterior flat battery which concerns on this invention is shown. Although FIG. 2 is a cross-sectional view, in order to facilitate understanding of each element, a part of the element is shown without hatching indicating that it is a cross-sectional view. In the cell body 11, a power generation element in which a plurality of sheet-like positive electrodes 30, separators 40, and sheet-like negative electrodes 50 are laminated is sandwiched between two laminate films 21 composed of a polymer and a metal, and heat-sealed from above and below. Thus, the power generation element is covered with a laminate outer package made of a laminate film.

  The sheet-like positive electrode 30 has a positive electrode mixture layer containing a positive electrode active material, a conductive additive, a binder and the like on at least one surface of a current collector 31 made of aluminum or an aluminum alloy. As shown in FIG. 2, the current collector 31 of the sheet-like positive electrode 30 is connected to the positive terminal lead 12. Further, the sheet-like negative electrode has a negative electrode mixture layer containing a negative electrode active material, a binder and the like on at least one surface of a current collector made of copper or a copper alloy. Current collector is connected to the negative terminal lead.

  1 and FIG. 2 show an example of a laminate-clad flat battery that can be used in the battery module of the present invention, and the laminate-clad flat battery according to the present invention includes: The present invention is not limited to those shown in these drawings. In addition, there are no particular restrictions on the components of the laminated exterior flat battery used in the battery module (active material for positive electrode and negative electrode, conductive additive, binder, separator, non-aqueous electrolyte, etc.), and conventionally known laminates Various components used in the outer flat battery can be used.

  The battery module of the present invention is formed by connecting two or more laminated exterior flat batteries as described above in series. FIG. 3 shows a top view of an example of a battery module in which five laminated exterior flat batteries are connected in series, and FIG. 4 shows an overall perspective view of the battery module of FIG. In FIGS. 3 and 4, some of the components that do not need to be described are the same as those in FIG.

  In the battery module of FIG. 3, the connecting conductor 14 is arranged between the negative electrode terminal lead 13 of the upper laminated outer flat battery in the drawing and the positive electrode terminal lead 12 of the laminated outer flat battery located below the battery. It is installed. One end of the connection conductor 14 is welded to the negative terminal lead 13 of the upper laminated outer flat battery, and the other end is welded to the positive terminal lead 12 of the lower laminated outer flat battery.

  4 is a perspective view schematically showing the external appearance of the battery module of FIG. 3 as described above, and is shown for the purpose of facilitating understanding of the overall structure of the battery module of FIG.

  3 and 4, a connection is made between the negative electrode terminal lead 13 of the upper laminated outer flat battery in FIG. 3 and the positive electrode terminal lead 12 of the laminated outer flat battery located on the lower side of the battery. Although the example in which the conductor 14 is arranged is shown, the arrangement position of the connection conductor 14 in the battery module of the present invention is not limited to the positions shown in FIGS. A connecting conductor 14 may be disposed between the positive terminal 12 of the laminated outer flat battery on the middle upper side and the negative terminal lead 13 of the laminated outer flat battery located below the battery. .

  FIG. 5 shows an example of the connection conductor 14. FIG. 5A is a plan view showing an example of the connection conductor 14, and FIG. 5B is a side view of FIG. As shown in FIG. 5, the connection conductor 14 has a buffer portion A. As shown in FIG. 5B, the shape of the buffer portion A is a wave shape (hereinafter, the shape of the buffer portion is simply abbreviated as “wave shape”) when the connection conductor 14 is viewed from the side in the length direction. There are things).

  In the battery module of the present invention, by using the connection conductor having the above-described buffer portion for the connection between the laminated exterior flat batteries, even if it receives an impact due to vibration or dropping, by the buffering action of the buffer portion in the connection conductor, It is possible to prevent the connection conductor from peeling off or falling off from the electrode terminal lead. That is, in the battery module of the present invention, even when a relatively large impact is applied such as dropping, the separation between the connection conductor and the electrode terminal lead can be suppressed. Further, in the battery module of the present invention, the connection conductor and the electrode terminal lead are slightly separated, and a gap is formed between them, which causes a relatively large impact (such as vibration) that increases the electric resistance of the battery module. Even when a small impact is applied, the separation between the connection conductor and the electrode terminal lead can be suppressed, so that an increase in electrical resistance can be prevented and the battery characteristics can be maintained well. For this reason, the battery module of the present invention maintains a good electrical connection between the batteries even when applied to an application (eg, an electric bicycle or an electric vehicle) that may be shocked by vibration or dropping. It has good battery characteristics and excellent long-term reliability.

  As the material of the connection conductor, those normally used as a material such as a current collector or electrode terminal lead in the battery field can be used, but for example, selected from the group consisting of Ni, Cu, Al and alloys thereof. It is preferable to use at least one kind of simple metal, or the surface of the simple metal that has been plated with Ni or Sn. Moreover, what was comprised with the clad material which consists of at least 2 sort (s) of metal selected from the group which consists of Ni, Cu, Al, and these alloys can be used preferably as a raw material of a connection conductor.

  For example, the connecting conductor may be formed by forming a part of a flat plate (foil) made of the above exemplified material into a wave shape and providing a buffer portion. Examples of the waveform in the buffer portion include a U shape, a V shape, and an S shape in a side view in the length direction of the connection conductor (the same applies to the waveform shape in the buffer portion). In addition, any one of U-shape, V-shape, S-shape, etc. may be a continuous shape of two or more (two, three, four, etc.). And the inverted shape may be a shape in which two or more sets (two sets, three sets, four sets, etc.) are alternately continued. Furthermore, it may be a continuous shape including two or more of these shapes. Incidentally, the connection conductor shown in FIG. 5 is an example having a buffer portion having a shape in which two S-shaped portions are continuous.

  The thickness of the connection conductor varies depending on the size of the laminated outer flat battery constituting the battery module, but is usually 100 to 300 μm. Moreover, although the magnitude | size of a connection conductor is fluctuate | varied with the size of the lamination exterior flat battery which comprises a battery module, length is 30-100 mm normally and width is 5-15 mm.

  The height of the waveform in the buffer portion of the connection conductor is, for example, 1 mm in the vertical length [length of I in FIG. 5B] between the highest point and the lowest point of the buffer portion in a side view of the connection conductor. It is preferable that it is above, and it is more preferable that it is 2 mm or more. If the waveform in the buffer portion has the above height, a more excellent buffer effect can be achieved. On the other hand, if the waveform at the buffer portion of the connection conductor is too high, contact between the connection conductors will occur, or the amount of metal used for the connection conductor will increase. The vertical length to the point is preferably 5 mm or less, and more preferably 4 mm or less.

  In addition, the hardness of the connection conductor is preferably 50 or more in terms of Vickers hardness (Hv) from the viewpoint of giving a certain degree of hardness so that the shape of the buffer portion can be satisfactorily maintained. In addition, since the buffer effect by a buffer part may become small when a connection conductor is too hard, it is preferable that the hardness of a connection conductor is 200 or less in Vickers hardness.

  As the size of the buffer part, for example, the area of the buffer part is preferably 70% or less, more preferably 50% or less, with respect to the total area of the connection conductor in plan view. If it is a connection conductor which provided the buffer part by such an area ratio, the more outstanding buffer effect can be show | played and welding with an electrode terminal lead can be made easier.

  Moreover, the position of the buffer part in a connection conductor should just be other than a welding planned location with an electrode terminal lead.

  In welding the electrode terminal lead and the connection conductor of the laminated exterior flat battery, various conventionally known welding methods such as a resistance welding method, a heat welding method, and an ultrasonic welding method can be employed. In addition, when welding a connection conductor with an electrode terminal lead, the area of the welding part of a connection conductor shall be 3-30% with respect to the total area in the planar view of a connection conductor from a viewpoint of achieving favorable joining. Is preferred.

  As described above, the battery module of the present invention has good bonding between the connection conductor and the electrode terminal lead that connect the laminated exterior flat batteries to each other even when subjected to an impact caused by vibration or dropping, and the connection conductor is dropped. Generation | occurrence | production of peeling etc. is suppressed. Therefore, the battery module of the present invention is suitable for uses such as those described above that are susceptible to impacts (for example, electric bicycles and electric vehicles), and even when applied to such uses, the battery life is long and good. It has good battery characteristics.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention.

Example A battery module was prepared by connecting five laminated exterior flat batteries having a length of 150 mm, a width of 90 mm, and a thickness of 5 mm in series.

The positive electrode of the laminated exterior flat battery was produced as follows. LiCoO _{2 as a} positive electrode active material: 90 parts by mass, acetylene black as a conductive auxiliary agent: 5 parts by mass, and polyvinylidene fluoride (PVDF) as a binder: 5 parts by mass are N-methyl-2-pyrrolidone (NMP) Were mixed in a uniform manner as a solvent to prepare a positive electrode mixture-containing paste.
This positive electrode mixture-containing paste was applied to one surface of a current collector made of aluminum foil and having a thickness of 15 μm. After drying, the other surface was similarly coated and dried. Then, the calendar process was performed and the positive mix layer with a thickness of 115 micrometers was formed. Next, the sheet is cut, and the size of the positive electrode mixture layer is 113 mm long × 63 mm wide, and the size of the current collector portion not covered with the positive electrode mixture layer is 15 mm long × 15 mm wide. A shaped positive electrode was produced.

  Moreover, the negative electrode of the laminated exterior flat battery was produced as follows. A negative electrode active material paste was prepared by mixing 95 parts by mass of graphite as a negative electrode active material and 5 parts by mass of PVDF as a binder so as to be uniform using NMP as a solvent. This negative electrode mixture-containing paste was applied to one side of a current collector made of copper foil and having a thickness of 8 μm, and after drying, the other side was similarly coated and dried. Then, the calendar process was performed and the negative mix layer whose thickness is 110 micrometers was formed. Next, the sheet is cut, and the size of the negative electrode mixture layer is 118 mm long × 67 mm wide, and the size of the current collector portion not covered with the negative electrode mixture layer is 13 mm long × 15 mm wide. A negative electrode was prepared.

  A laminated electrode group in which the sheet-like positive electrode and the sheet-like negative electrode were laminated with 15 sheet-like positive electrodes and 16 sheet-like negative electrodes each via a separator. As the separator, a microporous polyethylene film having a length of 120 mm × width of 67 mm × thickness of 20 μm was used. And the one end of each sheet-like positive electrode of a laminated electrode group was connected to the positive electrode terminal lead, and the one end of each sheet-like negative electrode was connected to the negative electrode terminal lead. The positive electrode terminal lead was an aluminum plate having a thickness of 200 μm, and the negative electrode terminal lead was a copper plate having a thickness of 200 μm subjected to Ni plating having a thickness of 1 μm. Further, the positive terminal lead and the negative terminal lead had a length of 35 mm and a width of 15 mm, respectively.

The laminated electrode group connected to the positive electrode terminal lead and the negative electrode terminal lead is made such that the free end side of the positive electrode terminal lead and the negative electrode terminal lead protrudes 10 mm to the outside, and the heat fusion insulating film layer is polypropylene and the metal film layer is aluminum. Were sandwiched between two laminate films, and three sides of these laminate films were heat-sealed. Next, after injecting a non-aqueous electrolyte from one side of the laminate film that was not heat-sealed, this one side was also heat-sealed to obtain a laminated exterior flat battery having the structure shown in FIG. The nonaqueous electrolyte was prepared by dissolving LiPF ₆ in a solvent in which ethylene carbonate (EC) and methyl ethyl carbonate (MEC) were mixed at a volume ratio of 1: 2 at a concentration of 1.0 mol / l. Using.

  The above-mentioned five laminated outer flat batteries are stacked as shown in FIG. 3, and the negative terminal lead 13 of the upper laminated outer flat battery in FIG. 3 and the positive terminal 12 of the laminated outer flat battery located therebelow. The connecting conductor 14 made of Ni was disposed between the end of the connecting conductor 14, and the end of the connecting conductor 14, the negative terminal lead 13 and the positive terminal lead 12 were joined to obtain a battery module. The connecting conductor 14 has a thickness of 200 μm, a width of 7 mm, and a length of 60 mm, and has a wave-shaped buffer portion in which two S-shaped shapes are continuous as shown in FIG. (Hv) is 150, and the vertical length between the highest point and the lowest point of the buffer [length of I in FIG. 5B] is 3 mm. Further, the connection conductor 14 is joined to the positive terminal lead 12 and the negative terminal lead 13 by using a heating and pressure welding apparatus between the connection conductor 14 and the positive terminal lead 12 or between the connection conductor 14 and the negative terminal lead 13. During this period, a voltage of 4.3 to 4.5 V was applied, and a current of 6.5 to 6.8 kA was applied by a heating welding method for 5 ms.

Comparative Example A battery module of a laminated exterior flat battery was produced in the same manner as in the example except that a connection conductor having no buffer portion was used.

  About the battery module of an Example and a comparative example, the battery resistance measurement after a vibration test and the drop test were done by the following method. The results are shown in Table 1.

<Measurement of battery resistance after vibration test>
A vibration test was performed on each of the ten battery modules of the examples and comparative examples, and the battery resistance after the test was measured. The vibration test was performed with a total of 10. Waveform: Sine wave, Frequency: 5 to 200 Hz linear sweep, Maximum amplitude: 10 mm, Vibration direction: X, Y, Z directions, Time: 3.5 hr / Vibration direction. The test was performed for 5 hours.

<Drop test>
Each 10 battery modules of Examples and Comparative Examples are dropped onto concrete from a height of 2 m, the state of joining between the connection conductor and the electrode terminal lead after dropping is observed, and the connection conductor and the electrode terminal lead are The number of battery modules in which peeling occurred at one place was examined.

  As can be seen from Table 1, in the battery module of the comparative example, since the connection conductor not provided with the buffer portion is welded to the electrode terminal lead, the connection conductor and the electrode terminal lead are separated after the drop test. It was observed. After the drop test, peeling between the positive terminal lead (Al material) and the connection conductor was observed. In addition, the battery module of the comparative example has a high battery resistance after the vibration test, and it is considered that the connection conductor and the electrode terminal lead are slightly separated by the vibration.

  On the other hand, in the battery module of the example configured using the connection conductor having the buffer portion, the connection conductor and the electrode terminal lead are not separated even after the drop test, and the battery resistance after the vibration test is low, Separation between the connection conductor and the electrode terminal lead due to such vibration is also suppressed.

  As described above, since the battery module of the example does not peel (drop off) between the connection conductor and the electrode terminal lead even when subjected to an impact such as vibration or drop, and has good battery characteristics, long-term reliability It can be said that the battery life can be maintained over a long period of time.

It is a whole perspective view showing roughly an example of a lamination exterior flat battery concerning the present invention. It is a longitudinal cross-sectional schematic diagram which shows an example of the principal part of the laminated exterior flat battery which concerns on this invention. It is the upper surface schematic diagram which shows an example of the battery module of the lamination exterior flat battery of this invention. FIG. 4 is an overall perspective view of the battery module of the laminated exterior flat battery of FIG. 3. It is the schematic which shows an example of a connection conductor, (a) Top view, (b) Side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laminated exterior flat battery 12 Positive electrode terminal lead 13 Negative electrode terminal lead 14 Connection conductor 30 Sheet-like positive electrode 31 Positive electrode collector 40 Separator 50 Sheet-like negative electrode 60 Welding part

Claims (3)

A sheet-like positive electrode having a positive electrode mixture layer on at least one side of a current collector made of aluminum or aluminum alloy, and a sheet-like negative electrode having a negative electrode mixture layer on at least one side of a current collector made of copper or copper alloy A laminated electrode group formed by laminating a plurality of sheets via a separator, and a laminate having a non-aqueous electrolyte inside the laminate outer body and having a positive terminal lead and a negative terminal lead projecting in the same direction outside the laminated outer body A battery module in which at least two exterior flat batteries are connected in series,
The connection between the batteries is disposed between the positive terminal lead of one battery and the negative terminal lead of the other battery, one end is welded to the positive terminal lead of the one battery, and the other end is the other It is made by the connecting conductor welded with the negative terminal lead of the battery of
The battery module of a laminated exterior flat battery, wherein the connection conductor has a buffer portion whose side shape in the length direction is a wave shape.   2. The connection conductor according to claim 1, wherein at least one metal selected from the group consisting of Ni, Cu, Al, and alloys thereof, or a surface of the metal simple substance subjected to Ni plating or Sn plating. The battery module of the laminated exterior flat battery of description. 2. The battery module of the laminated exterior flat battery according to claim 1, wherein the connecting conductor is made of a clad material made of at least two kinds of metals selected from the group consisting of Ni, Cu, Al, and alloys thereof. .

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