JP2006079987A - Hybrid battery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small hybrid battery system still having excellent heavy current characteristics and securing sufficiently high energy capacity. <P>SOLUTION: This hybrid battery system 1 is equipped with a high output type battery 10a and a high capacity type battery 10b. The high output type battery 10a can be charged by a current relatively heavier than that for the high capacity type battery 10b, and the high capacity type battery 10b has energy relatively higher than that of the high output type battery 10a. A group of high output type batteries 20a formed by connecting a plurality of the high output type batteries 10a in series and a group of high capacity type batteries 20b formed by connecting a plurality of the high capacity type batteries 10b in series are electrically connected in parallel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hybrid battery system configured by electrically connecting different types of batteries.

  2. Description of the Related Art Conventionally, an assembled battery in which a plurality of single type batteries are used and these batteries are electrically connected in series or in parallel is known.

  When an assembled battery having such a configuration requires an excellent large current characteristic and a large energy capacity, for example, a high-power battery that can be charged and discharged with a large current is supplied with a desired energy. There is a problem that the size of the assembled battery inevitably increases because it is necessary to cope with the number of connections according to the capacity in parallel.

An object of the present invention is to provide a small hybrid battery system that is excellent in large current characteristics and secures a sufficiently large energy capacity.
In order to achieve the above object, according to the present invention, a high-power battery and a high-capacity battery are provided, and the high-power battery can be charged and discharged with a relatively larger current than the high-capacity battery. The high-capacity battery has a relatively larger energy capacity than the high-power battery, and a hybrid battery system in which the high-power battery and the high-capacity battery are electrically connected in parallel is provided. Is done.

  In the present invention, a high-power battery and a high-capacity battery are electrically connected in parallel to constitute a hybrid battery system (assembled battery). Since a sufficiently large energy capacity can be secured by the high capacity battery, the system can be downsized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view showing an entire secondary battery according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.

  First, the secondary battery 10 in the embodiment of the present invention will be described. FIGS. 1 and 2 show one secondary battery 10 (unit battery, unit cell), and by connecting a plurality of the secondary batteries 10, A hybrid battery system described later is configured.

  The secondary battery 10 in this embodiment includes both a high-power battery 10a and a high-capacity battery 10b. The high-power battery 10a can be charged / discharged with a relatively larger current than the high-capacity battery 10b, and is a battery excellent in large current characteristics. In contrast, the high-capacity battery 10b has a relatively larger energy capacity than the high-power battery 10a, and is a high-energy capacity battery. In the following description, the common parts of the high-power battery 10a and the high-capacity battery 10b will be described as the secondary battery 10 without distinguishing them, and in particular, the high-power battery 10a and the high-capacity battery 10b. Only the differences will be described separately.

  The secondary battery 10 is a flat plate-like lithium ion secondary battery that can be stacked, and as shown in FIGS. 1 and 2, three positive plates 101, five separators 102, and three negative electrodes The plate 103, the positive electrode terminal 104, the negative electrode terminal 105, the upper exterior member 106, the lower exterior member 107, and an electrolyte (not particularly shown) are included, and have a total thickness of, for example, 10 mm or less. Among these, the positive electrode plate 101, the separator 102, the negative electrode plate 103, and the electrolyte are particularly referred to as a power generation element 108. By making the secondary battery 10 into a flat thin battery having a total thickness of 10 mm or less, the thinning of the separator 102 is promoted, so that high output can be achieved, and the heat dissipation area is improved and the temperature rise is suppressed. Therefore, the thermal performance can be improved.

  The positive electrode plate 101 constituting the power generation element 108 includes a positive electrode side current collector 101a extending to the positive electrode terminal 104, and positive electrode layers 101b and 101c formed on both main surfaces of a part of the positive electrode side current collector 101a, respectively. ,have.

  The positive electrode side current collector 101a of the positive electrode plate 101 is an electrochemically stable metal foil such as an aluminum foil, an aluminum alloy foil, a copper foil, or a nickel foil.

The positive electrode layer 101b of the positive electrode plate 101, 101c, for example, lithium-nickel composite oxide such as LiNiO _2, lithium-manganese-based composite oxide such as LiMn ₂ O _4, or a lithium-cobalt complex such as LiCoO _2, A mixture of a positive electrode active material such as an oxide or a chalcogen (S, Se, Te) compound, a conductive agent such as carbon black, and a binder such as an aqueous dispersion of polytetrafluoroethylene. Is applied to a part of both main surfaces of the positive electrode side current collector 101a, and dried and compressed.

  In particular, in the present embodiment, a lithium-manganese composite oxide is used as the positive electrode active material in the high-power battery 10a. On the other hand, in the high capacity battery 10b, a lithium / nickel composite oxide is used as a positive electrode active material.

  Generally, lithium-nickel composite oxides are more stable against heat than lithium-manganese composite oxides. In the present embodiment, as will be described later, when the hybrid battery system 1 is configured using the high-power battery 10a and the high-capacity battery 10b, the high-capacity battery 10b is in a position where the cooling conditions are worse. Be placed. Therefore, in the present embodiment, a lithium / nickel composite oxide is used as the positive electrode active material of the high-capacity battery 10b.

  The negative electrode plate 103 constituting the power generation element 108 includes a negative electrode side current collector 103a extending to the negative electrode terminal 105, and negative electrode layers 103b and 103c formed on both main surfaces of a part of the negative electrode side current collector 103a, respectively. And have.

  The negative electrode side current collector 103a of the negative electrode plate 103 is an electrochemically stable metal foil such as nickel foil, copper foil, stainless steel foil, or iron foil.

  The negative electrode layers 103b and 103c of the negative electrode plate 103 are made of, for example, lithium ions of the above positive electrode active material such as amorphous carbon, non-graphitizable carbon (hard carbon), graphitizable carbon, or graphite (graphite). Styrene butadiene rubber carbonized on the surface of carbon particles by mixing an aqueous dispersion of styrene butadiene rubber resin powder as a precursor material of an organic fired body with a negative electrode active material that occludes and discharges, and after drying Is mixed with a binder such as an acrylic resin emulsion, and this mixture is applied to both main surfaces of a part of the negative electrode current collector 103a, followed by drying and compression. It is formed by.

  In particular, in the present embodiment, hard carbon is used as the negative electrode active material in the high-power battery 10a. On the other hand, graphite is used as a negative electrode active material in the high capacity battery 10b.

  As a result, as described later, when the hybrid battery system 1 is configured using the high-power battery 10a and the high-capacity battery 10b, both the high-power battery 10a and the high-capacity battery 10b are used as negative electrode active materials. Compared with the case of using hard carbon, the output characteristics of the hybrid battery system 1 are improved. As shown in FIG. 3, generally, graphite has excellent output characteristics with respect to hard carbon, and when any of the batteries 10a and 10b uses hard carbon as a negative electrode active material. In contrast, the output characteristics of the entire hybrid battery system substantially match the curve (broken line) of the hard carbon in FIG. 3, whereas in the present embodiment, the output characteristics of the entire hybrid battery system 1 are improved by the presence of graphite. It is to do.

  Although it is conceivable to use graphite as a negative electrode active material for both the high-power battery 10a and the high-capacity battery 10b, graphite cannot be increased in comparison with hard carbon, so that it can be used as a hybrid battery system. High output cannot be achieved.

  Further, as in this embodiment, a negative electrode active material having a gradient in potential such as hard carbon is used for the high-power battery 10a, and a negative electrode active material having a flat potential such as graphite is used for the high-capacity battery 10b. By using it, it is possible to output in a wide range from a large current to a weak current, and it is possible to quickly equalize the hybrid battery system 1.

  Incidentally, the output can be increased by making the electrode plates 101 and 103 relatively thin, and the capacity can be increased by making the electrode plates 101 and 103 relatively thick. Therefore, in addition to the differentiation by the electrode active material as described above, the electrode plates 101 and 103 of the high-power battery 10a are relatively thin and the electrode plates 101 and 103 of the high-capacity battery 10b are relatively thick. By doing so, it is possible to differentiate between high output and high capacity.

  The separator 102 of the power generation element 108 prevents a short circuit between the positive electrode plate 101 and the negative electrode plate 103 described above, and may have a function of holding an electrolyte. This separator 102 is a microporous film made of polyolefin such as polyethylene (PE) or polypropylene (PP), for example. When an overcurrent flows, the pores of the layer are blocked by the heat generation and the current is cut off. It also has a function to

  The separator 102 of the present invention is not limited to a single-layer film such as polyolefin, but may be a three-layer structure in which a polypropylene film is sandwiched with a polyethylene film, or a laminate of a polyolefin microporous film and an organic nonwoven fabric or the like. I can do it. Thus, by making the separator 102 into multiple layers, various functions such as an overcurrent prevention function, an electrolyte holding function, and a separator shape maintenance (stiffness improvement) function can be provided.

  In the power generation element 108 described above, the positive electrode plates 101 and the negative electrode plates 103 are alternately stacked via the separators 102. The three positive plates 101 are respectively connected to the positive terminal 104 made of metal foil via the positive current collector 101a, while the three negative plates 103 are connected to the negative current collector 103a. In the same manner, each is connected to a negative electrode terminal 105 made of metal foil.

  In addition, the positive electrode plate 101, the separator 102, and the negative electrode plate 103 of the power generation element 108 are not limited to the above number in the present invention. For example, one positive electrode plate 101, three separators 102, and 1 The power generation element 108 can also be configured with a single negative plate 103, and can be configured by selecting the number of positive plates, separators, and negative plates as required.

  The positive electrode terminal 104 and the negative electrode terminal 105 are not particularly limited as long as they are electrochemically stable metal materials. Examples of the positive electrode terminal 104 include, for example, an aluminum foil and an aluminum alloy foil, similar to the positive electrode current collector 101a described above. , Copper foil, or nickel foil. Moreover, as the negative electrode terminal 105, nickel foil, copper foil, stainless steel foil, iron foil, etc. can be mentioned similarly to the above-mentioned negative electrode side collector 103a, for example.

  The power generation element 108 is accommodated and sealed in the upper exterior member 106 and the lower exterior member 107. The upper exterior member 106 and the lower exterior member 107 in the present embodiment are not particularly illustrated, but from the inner side to the outer side of the secondary battery 10, for example, an electrolytic solution such as polyethylene or polypropylene, and heat fusion properties. Consists of an inner layer composed of an excellent resin film, an intermediate layer composed of, for example, a metal foil such as aluminum, and a resin film excellent in electrical insulation, such as a polyamide resin or a polyester resin And a resin-metal foil film laminate material having a three-layer structure of the outer layer.

These exterior members 106 and 107 enclose the aforementioned power generation element 108, part of the positive electrode terminal 104 and part of the negative electrode terminal 105, and in the space formed by the exterior members 106 and 107, perchloric acid is added to the organic liquid solvent. A space formed by the exterior members 106 and 107 while injecting a liquid electrolyte in which a lithium salt such as lithium oxide (LiClO ₄ ), lithium borofluoride (LiBF ₄ ), or lithium hexafluorophosphate (LiPF ₆ ) is used as a solute Is vacuumed to seal the exterior members 106 and 107 by heat fusion along their outer peripheral edges by hot pressing.

  Examples of the organic liquid solvent include ester solvents such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC). Without being limited thereto, an ether solvent such as γ-butylactone (γ-BL), dietoshikiethane (DEE), or other mixed or prepared organic liquid solvent can be used as the ester solvent.

  The hybrid battery system 1 according to the first embodiment of the present invention using the high-power battery 10a and the high-capacity battery 10b described above will be described below.

  FIG. 4 is a circuit configuration diagram showing the hybrid battery system according to the embodiment of the present invention.

  As shown in FIG. 4, the hybrid battery system 1 according to the embodiment of the present invention includes a high-power battery group 20a in which a plurality of high-power batteries 10a are electrically connected in series, and a plurality of high-capacity batteries 10b. A high-power battery group 20b electrically connected in series, and the high-power battery group 20a and the high-capacity battery group 20b are electrically connected in parallel. In any battery group 20a, 20b, the number of batteries 10a, 10b constituting the battery group 20a, 20b is set according to a desired voltage.

  In the hybrid battery system 1, when high output charging / discharging is requested by the load 50, the high output battery group 20 a can cope with the short term. Further, when the output required from the load 50 is relatively small and surplus energy is accumulated in the high-power battery group 20a, the high-power battery group 20b to the high-capacity battery group 20b. Electric energy is transferred to On the other hand, when the output required from the load 50 is relatively small and the electric energy of the high-power battery group 20a is reduced, the high-capacity battery group 20b to the high-power battery group Electric energy moves to 20a. That is, it is possible to charge the battery group 20b or 20a in which the electric energy is reduced by the battery group 20a or 20b in which the electric energy is excessively stored, and the load 50 is always intermittently charged / discharged. It is possible to cope with output requests.

  FIG. 5A is a schematic perspective view showing the hybrid battery system according to the first embodiment of the present invention, and FIG. 5B is a schematic diagram showing a battery layout in the hybrid battery system shown in FIG. In FIG. 5A, the housing 30 is represented by a perspective view.

  In the hybrid battery system 1 according to the first embodiment of the present invention, as shown in FIG. 5A, the high-power battery group 20 a and the high-capacity battery group 20 b connected in parallel are provided inside the housing 30. Contained. A supply port 31 for supplying cooling air from the cooling device 40 into the housing 30 is formed on one end surface of the housing 30. An example of the cooling device 40 is a fan. Further, when the hybrid battery system 1 is used for an electric vehicle, traveling wind may be used as a refrigerant without providing the cooling device 40 exclusively.

In the hybrid battery system 1 according to the present embodiment, as shown in FIG.
The eight high-power batteries 10a stacked in two rows and four stages are connected in series by directly joining the electrode terminals 104 and 105 to form a high-power battery group 20a. Similarly, eight high-capacity batteries 10b stacked in two rows and four stages are connected in series with their electrode terminals 104 and 105 joined directly to form a high-capacity battery group 20b. As shown in FIG. 5B, these battery groups 20 a and 20 b are arranged with a high-power battery group 20 a on the upstream side toward the supply port 31 formed in the housing 30. A high capacity battery group 20b is arranged on the downstream side.

  When cooling air is supplied from the cooling device 40 into the housing 30 through the supply port 31, first, the cooling air passes between the high-power battery group 20 a and the inner wall surface of the housing 30. Then, the cooling air can pass between the high-capacity battery group 20 b and the inner wall surface of the housing 30.

  In this way, by adopting a layout in which the high-power battery 10a is arranged on the windward under favorable cooling conditions, the high-power battery 10a that generates relatively more heat than the high-capacity battery 10b is efficiently cooled. I can do it.

  6A is a schematic perspective view showing a hybrid battery system according to the second embodiment of the present invention, and FIG. 6B is a schematic view showing a battery layout in the hybrid battery system shown in FIG. 6A. In FIG. 6A, the housing 30 is represented by a perspective view.

  In the hybrid battery system 1 ′ according to the second embodiment of the present invention, as shown in FIG. 6 (A), the high-power battery group 20a and the high-capacity battery group connected in parallel as in the first embodiment. 20b is accommodated in the inside of the housing | casing 30 in which the supply port 31 which can supply the cooling air from the cooling device 40 was formed.

  In the hybrid battery system 1 ′ according to the present embodiment, as shown in FIG. 6 (A), eight high-power batteries stacked in four rows and two stages (the uppermost stage and the lowermost stage in FIG. 6 (A)). 10a is connected in series with the electrode terminals 104 and 105 joined to the bus bar 15 to form a high-power battery group 20a. Similarly, eight high-capacity batteries 10b stacked in four rows and two stages (two stages in FIG. 6A) are connected in series by joining their electrode terminals 104 and 105 to the bus bar 15. Thus, a high-capacity battery group 20b is configured. As shown in FIG. 6B, these battery groups 20a and 20b sandwich the high-capacity battery group 20b between the high-power battery groups 20a, and the high-power battery 20b by the high-power battery 20a. Is arranged so as to be substantially perpendicular to the refrigerant supply direction (arrow X direction in FIG. 6A) by the cooling device 40.

  Then, when cooling air is supplied from the cooling device 40 to the inside of the housing 30 through the supply port 31, the cooling air is particularly connected to the high-power battery group 20a and the housing stacked in the uppermost and lowermost stages. It is possible to pass between the inner wall surface of the body 30.

  As described above, by adopting a layout in which the high-power battery 20a is disposed at a position where the cooling air is easily touched and the cooling conditions are good, the high-power battery 10a that generates heat relatively more than the high-capacity battery 10b is obtained. It can be cooled efficiently.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

FIG. 1 is a plan view showing an entire secondary battery according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a graph showing an output comparison when graphite is used as the negative electrode active material and when hard carbon is used. FIG. 4 is a circuit configuration diagram showing the hybrid battery system according to the embodiment of the present invention. FIG. 5A is a schematic perspective view showing the hybrid battery system according to the first embodiment of the present invention, and FIG. 5B is a schematic diagram showing a battery layout in the hybrid battery system shown in FIG. FIG. FIG. 6A is a schematic perspective view showing a hybrid battery system according to the second embodiment of the present invention, and FIG. 6B is a schematic diagram showing a battery layout in the hybrid battery system shown in FIG. 6A. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 '... Hybrid battery system 10 ... Secondary battery 10a ... High output type battery 10b ... High capacity type battery 101 ... Positive electrode plate 102 ... Separator 103 ... Negative electrode plate 104 ... Positive electrode terminal 105 ... Negative electrode terminal 106 ... Upper exterior member 107 ... Lower exterior member 108 ... Power generation element 15 ... Bus bar 20a ... High power battery group 20b ... High capacity battery group 30 ... Case 31 ... Supply port 40 ... Cooling device 50 ... Load

Claims (5)

A high-power battery and a high-capacity battery
The high-power battery can be charged / discharged with a relatively larger current than the high-capacity battery,
The high capacity battery has a relatively large energy capacity than the high power battery,
A hybrid battery system in which the high-power battery and the high-capacity battery are electrically connected in parallel. The high power battery uses hard carbon as a negative electrode active material,
The hybrid battery system according to claim 1, wherein the high-capacity battery uses graphite as a negative electrode active material. A cooling means capable of supplying a refrigerant to the high-power battery and the high-capacity battery;
The high-power battery is disposed upstream toward the supply port to which the refrigerant is supplied;
The hybrid battery system according to claim 1 or 2, wherein the high-capacity battery is disposed on the downstream side toward the supply port. A plurality of the high power batteries;
A cooling means capable of supplying a refrigerant to the high-power battery and the high-capacity battery;
The high-power battery and the high-capacity battery include the high-capacity battery sandwiched between the plurality of high-power batteries, and the sandwiching direction is substantially orthogonal to the refrigerant supply direction. The hybrid battery system according to claim 1 or 2, arranged in such a manner. The high-power battery uses a lithium-manganese composite oxide as a positive electrode active material,
The hybrid battery system according to claim 1, wherein the high-capacity battery uses a lithium / nickel composite oxide as a positive electrode active material.

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