JP5305081B2 - Assembled battery - Google Patents

Description

  The present invention relates to an assembled battery in which a plurality of chargeable / dischargeable cells are connected in series.

  A storage battery (physical battery) such as a lithium secondary battery, nickel hydride battery or other secondary battery or capacitor is used as a single battery, and an assembled battery formed by connecting a plurality of the single batteries in series is used as a power source for obtaining high output. The importance is increasing as a power source for mounting, or as a power source for personal computers and portable terminals. In particular, an assembled battery in which a plurality of lithium secondary batteries that are lightweight and have a high energy density are connected in series as single cells is expected to be preferably used as a high-output power source for mounting on vehicles.

An assembled battery as a vehicle-mounted high-output power source has a configuration in which single cells are fastened and fixed by members or the like that connect the single cells, so that the batteries are efficiently and orderly arranged in a limited space. An assembled battery composed of a plurality of unit cells is likely to generate heat due to the internal resistance of each unit cell due to repeated charge and discharge, and thus is required to suppress the heat generation of each unit cell.
Patent documents 1-4 are mentioned as conventional technology about temperature control of this kind of unit cell. Patent Documents 1 and 2 disclose a device that heats or cools the battery itself by bringing a Peltier element into contact with the outer surface of the secondary battery. Patent Document 3 discloses a technique for adjusting the temperature by equalizing the internal resistance of batteries connected in parallel. Furthermore, Patent Document 4 discloses a system for reducing the temperature difference between the end portions of the positive electrode current collector and the negative electrode current collector.

JP 2006-127920 A Japanese Patent Laid-Open No. 11-176487 JP 2008-109841 A JP 2008-21669 A

  By the way, the electrode of the secondary battery has an electrode active material layer (specifically, a positive electrode active material layer and a negative electrode active material layer) mainly composed of an electrode active material on the surfaces of the positive electrode current collector and the negative electrode current collector. It has a formed configuration. For example, in the case of a lithium secondary battery, a positive electrode current collector (for example, aluminum) uses a metal having a higher electrical resistance than a negative electrode current collector (for example, copper), so the positive electrode has a larger internal resistance than the negative electrode. And tend to generate heat. In particular, in a secondary battery used for a vehicle-mounted power source that requires high output, the output tends to decrease as the difference in internal resistance between the positive and negative electrodes increases.

  Therefore, the present invention has been made in view of such a point, and is an assembled battery formed by connecting a plurality of secondary batteries in series, and by reducing the internal resistance difference between the positive electrode and the negative electrode of the battery, the output characteristics can be reduced. An object of the present invention is to provide an assembled battery with excellent performance.

An assembled battery provided by the present invention is an assembled battery in which a plurality of chargeable / dischargeable cells are connected in series, an electrode body including a positive electrode and a negative electrode, and a case for housing the electrode body; A plurality of unit cells (typically cells of the same shape) each having a positive electrode terminal and a negative electrode terminal which are electrically connected to the positive electrode and the negative electrode, respectively, and are disposed outside the case. Yes.
In the assembled battery, in at least a pair of unit cells adjacent to each other in the arrangement direction, a Peltier element is disposed between a positive terminal of one unit cell and a negative terminal of the other unit cell facing the positive terminal. The Peltier element is arranged to heat the positive terminal of the one unit cell and cool the counter negative terminal of the other unit cell when a direct current is applied to the element. It is characterized by that.

  In this specification, the “unit cell” is a term indicating individual storage elements that can be connected in series with each other to form an assembled battery. Unless specifically limited, batteries and capacitors (physical batteries) having various compositions are used. Include. The power storage element constituting the lithium secondary battery is a typical example included in the “unit cell” referred to herein, and a lithium secondary battery module (battery pack) including a plurality of such unit cells is here. It is a typical example of the disclosed “assembled battery”.

In the assembled battery having such a configuration, a plurality of chargeable / dischargeable single cells are connected in series, and in at least a pair of adjacent single cells, the positive electrode terminal of one of the single cells and the positive electrode terminal A Peltier element is provided between the opposite negative electrode terminal of the other unit cell facing the.
Here, a Peltier element is an element that is disposed at a joint between two types of opposing metals and is electrically connected in series to transfer heat from one metal to the other when a current flows. The Peltier element heat absorption part, which includes P-type and N-type thermoelectric semiconductors and current flows from the N-type to the P-type, absorbs and cools the heat of the metal bonded to the heat dissipation part. Further, in the heat dissipation part of the Peltier element in which current flows from the P type to the N type, the metal bonded to the heat dissipation part is heated. In the present invention, in at least a pair of unit cells adjacent to each other in the arrangement direction, the Peltier element is disposed between the positive terminal of one unit cell and the negative terminal of the other unit cell, and a direct current is passed through the unit. When this is done, the heat dissipating part of the Peltier element heats the positive electrode terminal and the heat absorbing part is arranged to cool the other negative electrode terminal.
Thereby, since the heat of the positive electrode terminal is conducted to the positive electrode current collector connected to the heated positive electrode terminal and the positive electrode active material is heated, the internal resistance of the positive electrode decreases. On the other hand, when the negative electrode terminal is cooled, the negative electrode active material is cooled via the negative electrode current collector connected to the negative electrode terminal, so that the internal resistance of the negative electrode increases. As a result, the difference between the internal resistances of the positive and negative electrodes of the unit cells facing each other in the arrangement direction is reduced, so that variation in battery characteristics of each unit cell is suppressed, and an assembled battery having high output performance can be provided. .

  Moreover, a vehicle provided with the assembled battery which concerns on this invention is provided. The assembled battery provided by the present invention may exhibit performance (for example, high output) suitable as an assembled battery mounted on a vehicle. Therefore, the assembled battery can be suitably used as a power source for a motor (electric motor) mounted on a vehicle such as an automobile including an electric motor such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

The assembled battery according to the present invention may be an assembled battery in which a rechargeable secondary battery is a single battery and a plurality of such single batteries are connected in series, and the configuration of the single battery is not particularly limited. . Hereinafter, an assembled battery formed by connecting a plurality of prismatic (typically flat) lithium secondary batteries in series will be described in detail as an example, but the present invention is intended to be limited to such an embodiment. is not. Therefore, a lithium secondary battery is preferable as an applied battery type of the present invention, but, for example, a nickel hydride battery, an electric double layer capacitor, and the like can be cited as suitable unit cell configurations. In addition, the shape of the unit cell is not particularly limited, and may be, for example, a rectangular parallelepiped shape, a cylindrical shape, etc., and the shape and size of the battery and other configurations are also used (typically for in-vehicle use). Can be changed appropriately.
In addition, in the following drawings, the same code | symbol is attached | subjected to the member and site | part which show | plays the same effect | action, and the overlapping description may be abbreviate | omitted or simplified. In addition, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view schematically showing a configuration of an assembled battery 100 according to an embodiment of the present invention. FIG. 2 is a schematic side view of the configuration of the assembled battery 100 shown in FIG. 1 as viewed from the side.
As shown in FIG. 1 and FIG. 2, the assembled battery 100 disclosed herein includes a plurality of (four in the present embodiment, four) single cells 20. The unit cell 20 includes a rectangular case 50 having a shape that can accommodate a flat-shaped wound electrode body 80 (which includes positive and negative electrode active materials, positive and negative electrode current collectors, a separator, and the like), which will be described later. On the upper front side of the case 50, a positive electrode terminal 60 that is electrically connected to the positive electrode of the wound electrode body 80 and a negative electrode terminal 62 that is electrically connected to the negative electrode are provided.
Further, between the adjacent single cells 20, one positive electrode terminal 60 and the other negative electrode terminal 62 which is adjacent to and opposite to each other are electrically connected by a connector (bus bar) 64. Thus, the assembled battery 100 of the desired voltage is constructed | assembled by connecting each cell 20 in series. Although not shown, the positive and negative terminals 60 and 62 at both ends connected in series are connected to the same type of assembled battery 100 separately prepared by a bus bar or the like, and the number of the assembled batteries 100 arranged is increased. Can do. Further, it can be pulled out from the terminals 60 and 62 by lead wires or the like.

First, the configuration of the unit cell 20 that can be used in the present embodiment and each material constituting the unit cell 20 will be described in detail.
FIG. 3 is a front view schematically showing an example of the wound electrode body 80.
As shown in FIG. 3, the wound electrode body 80 according to this embodiment includes a sheet-like positive electrode 82 (hereinafter referred to as “positive electrode sheet 82”) and a sheet-like negative electrode 84 (hereinafter referred to as “negative electrode sheet 84”). Laminated together with two sheet-like separators 86 (hereinafter referred to as “separator sheet 86”), the positive electrode sheet 82 and the negative electrode sheet 84 were wound while being slightly shifted, and then the obtained wound body was crushed from the side surface direction. This is a flat wound electrode body 80 produced by kidnapping.

  As a result of the winding electrode body 80 being wound with a slight shift as described above in the lateral direction with respect to the winding direction, part of the ends of the positive electrode sheet 82 and the negative electrode sheet 84 are respectively wound core portions 81 (that is, The positive electrode active material layer forming portion of the positive electrode sheet 82, the negative electrode active material layer forming portion of the negative electrode sheet 84, and the separator sheet 86 are closely wound outward). A positive electrode lead terminal 82B and a negative electrode lead terminal 84B are attached to the protruding portion (that is, the non-formed portion of the positive electrode active material layer) 82A and the protruding portion of the negative electrode side (that is, the non-formed portion of the negative electrode active material layer) 84A, respectively. Are electrically connected to the positive electrode terminal 60 and the negative electrode terminal 62, respectively.

In addition, the material and member itself which comprise this winding electrode body 80 may be the same as that of the electrode body of the conventional lithium secondary battery, and there is no restriction | limiting in particular.
For example, the positive electrode sheet 82 has a configuration in which a positive electrode active material layer for a lithium secondary battery is formed on a long positive electrode current collector. For the positive electrode current collector, an aluminum foil (this embodiment) or other metal foil suitable for the positive electrode is preferably used. As the positive electrode active material, one kind or two or more kinds of substances conventionally used in lithium secondary batteries can be used without any particular limitation. Preferable examples include lithium transition metal composite oxides such as lithium nickel composite oxide, lithium cobalt composite oxide, and lithium manganese composite oxide.
In addition to the positive electrode active material, a conductive material can be added to the positive electrode active material layer. As such a conductive material, a conductive powder material such as carbon powder or carbon fiber is preferably used. For example, acetylene black, furnace black, ketjen black, graphite powder and the like are preferable, and only one of these may be used or two or more may be used in combination. Furthermore, one or two or more polymer materials that can be blended as a binder in a general lithium secondary battery can be contained as necessary.

On the other hand, the negative electrode sheet 84 has a configuration in which a negative electrode active material layer for a lithium secondary battery is formed on a long negative electrode current collector. For the negative electrode current collector, a copper foil (this embodiment) or other metal foil suitable for the negative electrode is preferably used. As the negative electrode active material, one or more of materials conventionally used in lithium secondary batteries can be used without any particular limitation. A preferred example is carbon particles. A particulate carbon material (carbon particles) containing a graphite structure (layered structure) at least partially is preferably used. Any carbon material of a so-called graphitic material (graphite), non-graphitizable carbon material (hard carbon), easily graphitized carbon material (soft carbon), or a combination of these materials is preferably used. obtain.
In addition, the polymer material of 1 type, or 2 or more types which can be mix | blended as a binder with a general lithium secondary battery can be contained as needed.

  Moreover, as a suitable separator sheet 86 used between the positive / negative electrode sheets 82 and 84, the thing comprised by the porous polyolefin-type resin is mentioned. When a solid electrolyte or a gel electrolyte is used as the electrolyte, a separator may not be necessary (that is, in this case, the electrolyte itself can function as a separator). The electrode body 80 housed in the cell case 50 is not limited to the wound type. For example, it may be a laminated type electrode body in which a positive electrode sheet and a negative electrode sheet are alternately laminated together with a separator (or a solid or gel electrolyte that can also function as a separator).

Subsequently, the configuration of the electrolyte accommodated in the case 50 together with the wound electrode body 80 will be described. The electrolyte of this embodiment is a lithium salt such as LiPF ₆ . In the present embodiment, an appropriate amount (for example, concentration 1M) of a lithium salt such as LiPF ₆ is dissolved in a nonaqueous electrolytic solution such as a mixed solvent of diethyl carbonate and ethylene carbonate (for example, a mass ratio of 1: 1) to prepare an electrolytic solution. It is used as The unit cell 20 of the present embodiment is constructed by housing the wound electrode body 80 in the case 50 and injecting and sealing the electrolyte.
The material of the case 50 is not particularly limited as long as it is the same as that used in the conventional unit cell, but a relatively light metal case is suitable. For example, iron materials, such as stainless steel and nickel plating steel, aluminum, or its alloy is mentioned. Alternatively, a material that is easily distorted by a load at the time of restraint, for example, a metal case whose surface is coated with an insulating resin coating, a polyolefin resin such as polypropylene, or other synthetic resin cases may be used.

Next, the configuration of the assembled battery 100 of the present embodiment and each material constituting the battery will be described in detail.
As shown in FIGS. 1 and 2, the assembled battery 100 of the present embodiment has a configuration in which the unit cells 20 constructed as described above are connected in series in a predetermined direction. The plurality of unit cells 20 having the same shape are reversed one by one so that the positive terminals 60 and the negative terminals 62 are alternately arranged at regular intervals, while the wide surface of the case 50 (that is, in the case 50). The surface corresponding to the flat surface of the wound electrode body 80 to be accommodated is arranged in the facing direction. Then, the positive electrode terminal 60 and the negative electrode terminal 62 of the unit cells 20 facing in the arrangement direction are connected to an external circuit (which may be another battery connected in series with the battery) (bus bar) 64. Are attached, and the unit cells 20 are connected in series.

In addition, as shown in the drawing, the assembled battery 100 of the present embodiment includes a positive electrode terminal 60 of one unit cell 20 facing the arrangement direction between the pair of adjacent unit cells 20 and the other facing the positive electrode terminal 60. The Peltier elements 10 are respectively disposed between the unit cells 20 and the negative electrode terminal 62.
Here, the positive electrode current collector and the negative electrode current collector of the unit cell 20 used in the present embodiment are made of aluminum and copper, which are materials used for general lithium secondary batteries. Since aluminum has lower conductivity than copper, the internal resistance of the positive electrode of a lithium secondary battery using aluminum as the positive electrode current collector tends to be larger than the internal resistance of the negative electrode. In particular, in the cell 20 used for mounting on a vehicle that requires high output, the output as the assembled battery 100 decreases as the difference in internal resistance between the positive and negative electrodes increases. Therefore, in the present embodiment to which the present invention can be preferably applied, the Peltier element 10 is disposed between the positive electrode terminal 60 and the negative electrode terminal 62 of the unit cells 20 facing in the arrangement direction as described later, thereby The difference in internal resistance of the negative electrode can be reduced and the output characteristics can be improved.

The Peltier element 10 is disposed at a joint between opposing metals (here, positive electrode terminal 60 and negative electrode terminal 62) and is electrically connected in series to transfer heat from one metal to the other when current flows. It is an element to be made. Utilizing the principle of operation of the element 10, the positive electrode terminal 60 is disposed (contacted) on the heat radiating portion side of the element 10, and the negative electrode terminal 62 is disposed (contacted) on the heat absorbing portion side of the element 10, By passing a predetermined direct current through the Peltier element 10, the positive electrode terminal 60 is heated and the other negative electrode terminal 62 is cooled. As a result of this configuration, the positive electrode terminal 60 is heated, so that the positive electrode active material is heated via the positive electrode current collector (typically, the positive electrode lead terminal 82B) connected to the positive electrode terminal 60. The internal resistance is reduced. On the other hand, since the negative electrode terminal 62 is cooled, the negative electrode active material is cooled via the negative electrode current collector (typically, the negative electrode lead terminal 84B) connected to the negative electrode terminal 62, so that the internal resistance of the negative electrode is reduced. To increase. As a result, the difference between the internal resistances of the positive and negative electrodes of the unit cells 20 facing each other in the arrangement direction is reduced, and variation in battery characteristics (for example, output characteristics) of each unit cell 20 is suppressed, and the assembled battery 100 having high output performance. Can be provided.
In addition, although it is a means to supply a direct current to the said Peltier element 10 arrange | positioned between the positive electrode terminal 60 and the negative electrode terminal 62 which adjoin (opposite), the external supply power source which is not shown in figure and each Peltier element 10 are connected. It may be by means of supplying a direct current of a predetermined voltage to each Peltier element 10 or a series of Peltier elements 10 connected in series by a dedicated line (circuit), or may be connected in series via a connector (bus bar) 64. A direct current may be supplied to each Peltier element 10 using a charge / discharge circuit.

  Furthermore, a predetermined-shaped interval holding plate (spacer) 40 is arranged in close contact with the wide surface of the case 50 between the arranged unit cells 20 and on both sides in the unit cell 20 arrangement direction. The spacing plate 40 is preferably made of a material and / or shape that can function as a heat radiating member for radiating heat generated in each unit cell 20 during use. For example, a spacing plate 40 made of metal with good thermal conductivity or lightweight and hard polypropylene or other synthetic resin is suitable. In addition, as shown in the drawing, a spacing plate 40 having an uneven surface 41 like a comb shape is suitable for dissipating heat by the internal resistance between the single cells 20.

  Thus, as shown in FIGS. 1 and 2, a restraining member according to the present embodiment is arranged around the unit cells 20 and the spacing plate 40 arranged as described above. That is, as shown in the figure, a pair of restraining plates 76A and 76B are disposed in close contact with the outer side of the spacing plate 40 disposed on both sides of the unit cell 20 group. Further, a fastening beam member 72 is attached to both side surfaces of the unit cell group 20 so as to bridge the pair of restraining plates 76A and 76B. The unit cell 20 and the spacing plate 40 can be restrained by tightening and fixing the ends of the beam member 72 to the restraining plates 76A and 76B with screws 78. Thereby, the assembled battery 100 which concerns on this embodiment can be constructed | assembled.

  The assembled battery 100 according to the present embodiment can be suitably used as a power source for a motor (electric motor) mounted on a vehicle such as an automobile. Therefore, the present invention can provide a vehicle (typically, an automobile equipped with an electric motor such as a hybrid automobile, an electric automobile, and a fuel cell automobile) provided with the assembled battery 100 as a power source.

Although the preferred embodiment of the assembled battery manufacturing method of the present invention and the assembled battery that can be manufactured by the method has been described in detail above, the present invention is not limited to the method and the assembled battery having such a configuration. For example, the electrode body accommodated in the cell case is not limited to the wound type. It may be a laminate type electrode body in which positive electrode sheets and negative electrode sheets are alternately laminated together with a separator (or a solid or gel electrolyte that can also function as a separator).
In addition, the type of unit cell is not limited to the above-described lithium secondary battery, but batteries having various contents with different electrode body constituent materials and electrolytes, for example, lithium metal batteries, nickel metal hydride batteries, nickel batteries having lithium metal or lithium alloy as a negative electrode It may be a cadmium battery or an electric double layer capacitor.

  Further, the assembled battery 100 shown in FIG. 1 has a simple configuration in order to explain the present invention. However, various modifications and additions of equipment can be made without impairing the configuration and effects of the present invention. It is clear to the contractor. For example, when mounted on a vehicle such as an automobile, more unit cells 20 can be connected in series, and an exterior cover for protecting the main part (unit cell group, etc.) of the assembled battery is provided on a predetermined part of the vehicle. Components for fixing the assembled battery, components for interconnecting a plurality of assembled batteries (battery modules), etc. may be equipped, but the presence or absence of such equipment affects the technical scope of the present invention. is not.

It is a perspective view showing typically the composition of battery pack 100 concerning one embodiment of the present invention. It is the side surface schematic diagram which looked at the structure of the assembled battery 100 shown in FIG. 1 from the side surface. 4 is a front view schematically showing an example of a wound electrode body 80. FIG.

Explanation of symbols

10 Peltier element 20 Single cell 40 Spacing plate (spacer)
41 Concavity and convexity surface 50 Case 60 Positive electrode terminal 62 Negative electrode terminal 64 Connector (bus bar)
72 Beam material 76A, 76B Restraint plate 78 Screw 80 Electrode body 81 Winding core portion 82 Positive electrode sheet 82A Positive electrode side protruding portion 82B Positive electrode lead terminal 84 Negative electrode sheet 84A Negative electrode side protruding portion 84B Negative electrode lead terminal 86 Separator sheet 100 Assembly battery

Claims (1)

An electrode body comprising a positive electrode and a negative electrode;
A case for housing the electrode body;
A terminal electrically connected to the positive electrode and the negative electrode, respectively, and a positive electrode terminal and a negative electrode terminal disposed outside the case;
An assembled battery in which a plurality of chargeable / dischargeable cells are connected in series,
In at least a pair of unit cells adjacent in the arrangement direction, a Peltier element is disposed between the positive terminal of one unit cell and the negative terminal of the other unit cell facing the positive terminal,
Here, the Peltier element is disposed so as to heat the positive terminal of the one unit cell and cool the opposing negative terminal of the other unit cell when a direct current is applied to the element. A battery pack characterized by comprising:

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