JP2007257849A - Battery module of laminate outer package flat battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery module of laminate outer package flat battery in which electric jointing of laminate outer package flat batteries is excellent and electric property is improved. <P>SOLUTION: The battery module has at least two or more laminate outer package flat batteries connected in series or in parallel which have a laminate electrode group in which a positive electrode of sheet shape and a negative electrode of sheet shape are laminated respectively plural pieces through a separator, and a nonaqueous electrolyte in a laminate outer package, and have a positive electrode terminal lead and a negative electrode terminal lead protruded to the outside of the laminate outer package. In the laminate outer package flat batteries connected, the positive electrode terminal leads themselves, the negative electrode terminal leads themselves or the positive electrode terminal lead and the negative electrode terminal lead are welded and fixed by a mechanical crimping means, and the distance from the outer package periphery to the center position of the fixing part by the mechanical crimping means is 4-20 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery module of a laminate-clad flat battery, and more specifically, the electrode terminal leads of each laminate-clad flat battery are firmly joined to each other, and it is reliable for a long time against vibration and dropping. The present invention relates to a battery module of a laminated exterior flat battery, which is expected to have good properties.

  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 to form a battery module, the positive electrode terminal leads of the batteries, the negative electrode terminal leads, or the positive electrode terminal lead and the negative electrode terminal lead are directly connected. It can be said that it is effective in achieving a compact battery module.

  On the other hand, when the battery module is applied to an application such as an electric bicycle or an electric vehicle, it is easy to receive an impact due to vibration, dropping, etc., so that the connection between the batteries is maintained even if the impact is received. Thus, it is required to have sufficient bonding strength.

  As a method for connecting the electrode terminal leads of the battery, for example, welding is conceivable. In particular, the positive electrode terminal lead and the negative electrode terminal lead are generally made of different kinds of metals, and such different kinds of metals are used. It is difficult to obtain high joint strength by welding. Further, for example, even for the same kind of metals, aluminum that is widely used for the positive electrode terminal lead is not suitable for welding, and there is a problem that sufficient strength cannot be obtained.

  Although it is not a technology related to a battery module, for example, in Patent Document 2, heating and pressurization are performed in joining an aluminum electrode and a copper lead wire, and the surface of the copper lead wire is lower than that of copper. A technique has been disclosed that can increase the bonding strength between an aluminum electrode and a copper lead by forming a metal film made of a metal having a melting point.

  Patent Document 3 discloses a technique for fixing heat-sealed portions sandwiching electrode terminal leads in a laminate-clad flat battery by clamping means provided at the top and bottom thereof, and further the laminate-clad flat battery. In order to form a battery module by combining a plurality of battery packs, there is also shown a technique in which two laminated outer flat batteries are bonded to each other so that two heat-sealing portions are fixed by a pair of clamping means.

JP 11-224652 A JP 2002-260630 A JP 2004-63278 A

  However, the bonding strength between the aluminum electrode and the copper lead wire shown in the above-mentioned Patent Document 2 is resistant to the impact caused by the vibration or dropping of the battery module when applied to an application such as an electric bicycle or an electric vehicle. This is insufficient to maintain the connection between the terminal leads.

  Further, the fixing means for the two laminated outer flat batteries in Patent Document 3 is considered to have a certain effect in preventing the positional deviation between the laminated outer flat batteries when subjected to an impact caused by vibration or dropping. However, the connection between the electrode terminal leads of the laminated outer flat battery is not yet solved.

  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 with improved battery characteristics while improving electrical bonding between the laminated-clad flat batteries. There is to do.

  The battery module of the laminated exterior flat battery of the present invention that has achieved the above object is a sheet-like positive electrode in which a positive electrode mixture layer is formed on at least one surface of an aluminum current collector, and a copper current collector. A laminated electrode group in which a plurality of sheet-like negative electrodes each having a negative electrode mixture layer formed on at least one side thereof are laminated via a separator, and a non-aqueous electrolyte in the laminate outer package, A laminated external flat battery having a positive electrode terminal lead and a negative electrode terminal lead protruding outside the body, wherein the laminated external flat batteries are connected in series and / or in parallel at least two or more. The positive terminal leads, the negative terminal leads, or the positive terminal lead and the negative terminal lead are welded and mechanically held together. The center position of the portion fixed by the step and fixed from the edge of the exterior body by the mechanical clamping means at the portion of the positive terminal lead and the negative terminal lead projecting outside the laminate exterior body The length A is 4 to 20 mm.

  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 applications that may be subjected to impacts 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 includes a cell body 11 and two electrode terminal leads (a positive terminal lead 12 and a negative terminal lead 13) protruding from the cell body 11, that is, the laminated exterior body. 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.

  FIG. 2 is an overall perspective view schematically showing another example of the laminated exterior flat battery according to the present invention. In the laminate-sheathed flat battery, the positive electrode terminal lead 12 and the negative electrode terminal lead 13 may have a structure projecting in parallel, for example, from the same side of the cell body 11 (laminate sheath body) as shown in FIG. 11 (laminate outer package) may protrude from different sides. For example, as shown in FIG. 2, the cell body 11 (laminate outer package) protrudes from opposite sides (that is, the positive terminal lead 12 and the negative terminal lead 13 protrude in opposite directions in a plan view of the battery. Structure).

  In FIG. 3, the longitudinal cross-sectional schematic of the principal part of the laminated exterior flat battery which concerns on this invention is shown. Although FIG. 3 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 (including an aluminum alloy). As shown in FIG. 3, the current collector 31 of the sheet-like positive electrode 30 is connected to the positive terminal lead 12. In addition, the sheet-like negative electrode has a negative electrode mixture layer containing a negative electrode active material, a binder, etc. on at least one surface of a current collector made of copper (including a copper alloy). The current collector of the negative electrode 40 is connected to the negative terminal lead. Note that A in FIG. 3 is the same as A described in FIG.

  The laminated outer flat battery shown in FIGS. 1 to 3 shows an example of a laminated outer flat battery that can be used in the battery module of the present invention. However, the present invention is not limited to those shown in the 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 and / or in parallel. FIG. 4 shows a schematic vertical sectional view of an essential part of an example of a battery module in which two laminated outer flat batteries are connected in series. In FIG. 4, constituent elements that do not need to be described are the same as those in FIG. 3, and thus the reference numerals are omitted. FIG. 4 is a cross-sectional view. Like FIG. 3, 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.

  FIG. 4 shows a portion where the positive electrode terminal lead 12 of the upper laminated outer flat battery in the drawing and the negative electrode terminal lead 13 of the lower laminated outer flat battery in the drawing are connected. The mechanical clamping means 60 and welding (not shown) are used in combination. In FIG. 4, A is the length from the edge of the laminate outer package to the center position of the portion fixed by the mechanical clamping means 60 in the portion of the positive electrode terminal lead 12 protruding outside the laminate outer package. (The same applies to FIG. 5 described later).

  FIG. 5 is a plan view of the main part of the battery module of FIG. 4. In FIG. 5, a welding portion (welded portion) 70 (with mechanical clamping means 60 for connecting the electrode terminal leads to each other is shown. 2 points × 2 places).

  In the battery module of the present invention, the connection between the laminated exterior flat batteries is performed by connecting the positive terminal leads of both batteries, the negative terminal leads of both batteries, or the positive terminal lead of one battery and the negative terminal lead of the other battery. Is performed by welding and fixing with mechanical clamping means, so that, for example, the bonding strength can be increased as compared with the case where the connection is made only by welding. Therefore, even when the battery module is applied to an application (for example, an electric bicycle or an electric vehicle) that may be subjected to an impact due to vibration or dropping, the electrode terminal lead can be prevented from falling off.

  Further, if the electrode terminal leads are connected only by the mechanical clamping means, a minute gap is generated between the electrode terminal leads due to the vibration received by the battery module, and the internal resistance of the battery module may increase and the battery characteristics may deteriorate. is there. However, in the battery module of the present invention, since mechanical clamping means and welding are used in combination, the occurrence of a gap between the electrode terminal leads can be suppressed even when subjected to vibration. Can be increased.

  The welding between the electrode terminal leads is preferably performed by, for example, heat welding, ultrasonic welding, resistance welding, or the like.

  Moreover, as the mechanical clamping means for connecting the electrode terminal leads, for example, riveting and screwing are preferable. In addition, when adopting riveting or screwing as the mechanical clamping means, it is necessary to provide a missing portion for passing the rivet or screw through the electrode terminal lead. FIG. 6 shows an example of the defect 61 provided in the electrode lead terminal (the positive electrode lead terminal 12). For example, as shown in (a), the defect 61 may be a through hole, and (b) As shown in FIG. Further, the defect portion has a shape other than that shown in FIG. 6 [for example, if it is a through-hole, besides the circle shown in FIG. 6A, an ellipse, a square, a rectangle (all in a plan view), etc. ].

  The length A is 4 to 20 mm. When A is shorter than 4 mm, when the electrode terminal lead is fixed by the mechanical clamping means, the heat-bonding strength (seal) (Strength) may be reduced. On the other hand, when A is longer than 20 mm, the length of the electrode terminal lead is increased and the internal resistance of the battery is increased.

  As described above, the battery module of the present invention has strong bonding between the electrode terminal leads that connect the laminated exterior flat batteries to each other even when subjected to an impact due to vibration, drop, etc. Generation of gaps between terminal leads 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. Battery characteristics can be exhibited.

  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 1
Two laminated exterior flat batteries having a length of 150 mm, a width of 90 mm, and a thickness of 5 mm were connected in series to produce a battery module.

As the positive electrode of the laminated exterior flat battery, one produced as follows was used. 90 parts by mass of LiCoO _{2 as a} positive electrode active material, 5 parts by mass of acetylene black as a conductive auxiliary agent, and 5 parts by mass of polyvinylidene fluoride (PVDF) as a binder were added to 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. Thereafter, a calendar process was performed to form a positive electrode mixture layer having a thickness of 115 μm. Thereafter, this is cut into a sheet shape in which 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 positive electrode was produced.

  Moreover, what was produced as follows was used for the negative electrode of a laminated exterior flat battery. 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. Thereafter, this is cut into a sheet shape in which 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 produced.

  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. For the separator, microporous polyethylene having a length of 120 mm, a width of 67 mm, and a 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 plated with a nickel plate having a thickness of 1 μm. The positive terminal lead and the negative terminal lead have a length of 35 mm and a width of 15 mm, respectively, and a through hole of φ5 mm is provided at a position 5 mm from the tip of the sheet-like positive electrode and the sheet-like negative electrode connected to the current collector. There was one.

The laminated electrode group connected to the positive electrode terminal lead and the negative electrode terminal lead is arranged such that the free end side of the positive electrode terminal lead and the negative electrode terminal lead protrudes to the outside, while the heat fusion insulating film layer is made of polypropylene and the metal film layer is made of aluminum The laminate film was 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.

  About two said laminated exterior flat batteries, one positive electrode terminal lead and the other negative electrode terminal lead were connected, and it was set as the battery module. First, by applying a voltage of 4.3 to 4.5 V between two electrode terminal leads to be connected by a heat welding method, a current of 6.5 to 6.8 kA is applied to join the two electrode terminal leads. did. The energization time was 5 ms. Thereafter, screws were passed through the through holes of the two joined electrode terminal leads, and both electrode terminal leads were clamped and fixed with these screws to obtain a battery module having the structure shown in FIG. For each of the positive and negative terminal leads, the length A from the center of the screwing to the edge of the laminate outer package was 4.5 mm.

Example 2
For each of the positive and negative terminal leads, a battery module was produced in the same manner as in Example 1 except that the length A from the center of screwing to the edge of the laminate outer package was 20 mm.

Comparative Example 1
A battery module was produced in the same manner as in Example 1 except that the fixing of the electrode terminal leads with screws was omitted.

Comparative Example 2
A battery module was produced in the same manner as in Example 1 except that the joining of the electrode lead terminals by welding was omitted.

Comparative Example 3
For each of the positive and negative electrode terminal leads, a battery module was produced in the same manner as in Example 1 except that the length A from the center of screwing to the edge of the laminate outer package was 3 mm.

Comparative Example 4
For each of the positive and negative terminal leads, a battery module was produced in the same manner as in Example 1 except that the length A from the center of screwing to the edge of the laminate outer package was 45 mm.

  A vibration test was performed on each of the ten battery modules of Examples 1-2 and Comparative Examples 1-4, 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. The results are shown in Table 1.

  As can be seen from Table 1, the battery modules of Examples 1 and 2 have low battery resistance after the vibration test and good battery characteristics. On the other hand, the battery module of Comparative Example 1 that does not employ mechanical clamping means (screw fastening) for connection between electrode terminal leads, and the battery of Comparative Example 2 that does not employ welding for connection between electrode terminal leads. In the battery module of Comparative Example 4 in which the length A from the center of screwing of each of the module and the positive / negative terminal lead to the edge of the laminate outer package is long, the battery resistance after the vibration test is high and the battery characteristics are inferior. Yes. In the battery module of Comparative Example 2, it is considered that the battery resistance after the vibration test was high because a gap was generated between the electrode terminal leads by the vibration test. In Comparative Example 3 in which the length A from the center of screwing of each of the positive and negative terminal leads to the edge of the laminate outer package is short, the battery resistance after the vibration test is low and the battery characteristics are good. Since the length A is too short, for example, the heat-sealed portion of the laminate outer package is deformed at the time of screwing, and thus the heat-sealed portion may be affected when fixing by the mechanical clamping means.

  Moreover, about the battery module of Example 1 and Comparative Examples 1-2, the drop test was done after said vibration test, and the state of the electrode terminal lead after that was observed. The drop test was performed by dropping the battery module on the concrete from a height of 2 m. The results are shown in Table 2.

  As can be seen from Table 2, the battery module of Example 1 shows no peeling between the electrode terminal leads even after the drop test. On the other hand, in the battery module of Comparative Example 1 that does not employ mechanical clamping means (screw fastening) for connection between the electrode terminal leads, there is a case in which the electrode terminal leads are separated by a drop test. The bonding between the terminal leads was inferior. In addition, in the battery module of Comparative Example 2 in which welding was not adopted for the connection between the electrode terminal leads, the electrode terminal lead was not peeled off by the drop test, but as described above, the battery resistance after the vibration test was high, It has the disadvantage of poor battery characteristics.

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

It is a whole perspective view showing roughly an example of a lamination exterior flat battery concerning the present invention. It is a whole perspective view showing roughly other examples 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 a principal part longitudinal cross-sectional schematic diagram which shows an example of the battery module of the laminate-sheathed flat battery of this invention. It is a principal part top view of the battery module of FIG. It is a top view which shows the example of the defect | deletion part provided in the electrode terminal lead of the lamination exterior flat battery which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laminated exterior flat battery 12 Positive electrode terminal lead 13 Negative electrode terminal lead 30 Sheet-like positive electrode 31 Positive electrode collector 40 Separator 50 Sheet-like negative electrode 60 Mechanical clamping means 61 Defect part 70 Welding part

Claims (4)

A sheet-like positive electrode formed by forming a positive electrode mixture layer on at least one surface of an aluminum current collector, and a sheet-shaped negative electrode formed by forming a negative electrode mixture layer on at least one surface of a copper current collector, A laminated outer flat battery having a laminated electrode group formed by laminating a plurality of sheets via a separator, and a non-aqueous electrolyte in the laminated outer package, and having a positive electrode terminal lead and a negative electrode terminal lead protruding outside the laminated outer package. Is a battery module connected in series and / or parallel in at least two or more,
Between the laminated exterior flat batteries connected, the positive terminal leads, the negative terminal leads, or the positive terminal lead and the negative terminal lead are welded and fixed by mechanical clamping means,
The length A from the edge of the exterior body to the center position of the portion fixed by the mechanical clamping means in the portion of the positive electrode terminal lead and the negative electrode terminal lead that protrudes outside the laminate exterior body is 4 to 20 mm. A battery module of a laminated exterior flat battery characterized by the above.   The battery module of the laminated exterior flat battery according to claim 1, wherein the welding is performed by heat welding, ultrasonic welding, or resistance welding.   The battery module of a laminated exterior flat battery according to claim 1 or 2, wherein the mechanical clamping means is riveting or screwing. The battery module of the laminated exterior flat battery according to any one of claims 1 to 3, wherein the positive electrode terminal lead is made of aluminum, and the negative electrode terminal lead is made of copper, nickel, or copper having nickel plating or tin plating.

Images