JP2007213990A - Battery module, battery pack, and vehicle with same battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate formation of a battery module using a bipolar battery. <P>SOLUTION: The battery module is provided with a plurality of bipolar batteries 40, a pair of conductive holding plates 50, 60 which sandwich and hold the plurality of the bipolar batteries from both sides along a direction for laminating bipolar electrodes, and electrically connect the bipolar batteries with each other. The plurality of the bipolar batteries are in contact with each other through a conductive elastic body 90, and an elastic modulus of the elastic body is 1.0×10<SP>3</SP>-7.5×10<SP>6</SP>Pa. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a battery module in which bipolar batteries are stacked, a battery pack in which a plurality of battery modules are electrically connected, and a vehicle on which these batteries are mounted.

  In recent years, reduction of carbon dioxide emissions has been strongly desired for environmental protection. In the automobile industry, there are high expectations for reducing carbon dioxide emissions by introducing electric vehicles (EVs) and hybrid electric vehicles (HEVs), and we are eager to develop secondary batteries for motor drives that hold the key to their practical application. Has been done. As a secondary battery, attention is focused on a stacked bipolar battery that can achieve high energy density and high output density (see Patent Document 1).

  A typical bipolar battery includes a battery element in which a plurality of bipolar electrodes are connected in series, that is, stacked with an electrolyte layer interposed therebetween, an outer packaging material that encloses and seals the entire battery element, and an outer packaging material for taking out current. And a terminal led out to the outside. In the bipolar electrode, a positive electrode is formed by providing a positive electrode active material layer on one surface of a current collector, and a negative electrode is formed by providing a negative electrode active material layer on the other surface. A single battery layer is formed by sequentially stacking a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, and the single battery layer is sandwiched between a pair of current collectors. Bipolar batteries have the advantage that the current flows in the direction in which the bipolar electrodes are stacked, that is, in the thickness direction of the battery, in the battery element, so the current path is short and the current loss is small.

In order to obtain the required capacity and voltage, a plurality of bipolar batteries are electrically connected to form a battery module, or a plurality of battery modules are electrically connected to form an assembled battery. ing. The battery module is a kind of assembled battery in that it includes a plurality of electrically connected bipolar batteries. In this specification, a unit unit for assembling an “assembled battery” is referred to as a “battery module”. I will call it.
JP 2001-236946 A

  When forming a battery module, the operation | work which seals a battery element with an exterior material is required previously, and a series of operation | work which forms a battery module cannot be simplified.

  In addition, in order to electrically connect a plurality of bipolar batteries, terminals led out from the exterior material must be joined together by welding or connected via a connecting member such as a bus bar. In this respect, a series of operations for forming the battery module cannot be simplified.

  An object of the present invention is to facilitate the formation of a battery module using a bipolar battery, and to facilitate the formation of an assembled battery formed by electrically connecting a plurality of battery modules through the battery module.

In order to achieve the above object, the invention described in claim 1 is characterized in that a bipolar electrode having a positive electrode layer disposed on one surface of a current collector and a negative electrode layer disposed on the other surface is laminated with an electrolyte layer interposed therebetween. A plurality of battery elements, and a plurality of seal parts arranged around each of the unit cell layers formed by laminating the positive electrode layer, the electrolyte layer, and the negative electrode layer and blocking contact between the unit cell layer and the outside air. Bipolar battery,
A pair of conductive holding plates that sandwich and hold a plurality of the bipolar batteries from both sides along the direction in which the bipolar electrodes are stacked and electrically connect the bipolar batteries; and
The plurality of bipolar batteries are contacted via an elastic body having conductivity,
The elastic modulus of the elastic body is 1.0 × 10 ^{3 to} 7.5 × 10 ⁶ Pa.

According to the battery module of the present invention, a plurality of bipolar batteries are in contact with each other via an elastic body having conductivity, and the elastic modulus of the elastic body is 1.0 × 10 ^{3 to} 7.5 × 10 ⁶ Pa. Therefore, the unevenness of the contact surface between the bipolar batteries can be absorbed and brought into surface contact by the elastic force of the elastic body having the elastic modulus in the above range, and since the elastic body has conductivity, the bipolar batteries are electrically connected to each other. Can be connected. Therefore, bipolar batteries can be brought into electrical contact with each other without increasing the contact resistance, and the work of welding the bipolar battery terminals to each other becomes unnecessary, simplifying a series of manufacturing operations. Thus, a battery module can be easily manufactured.

  Embodiments of a battery module, an assembled battery, and a vehicle equipped with these batteries according to the present invention will be described below in detail with reference to the drawings. In the drawings cited in the following embodiments, the thickness and shape of each layer constituting the battery are exaggerated, but this is done to facilitate understanding of the contents of the invention. This is not consistent with the thickness or shape of each layer in an actual battery.

(First embodiment)
1 is a cross-sectional view showing a stacked structure of the battery module 11 according to the first embodiment of the present invention, FIG. 2 is a cross-sectional view showing the bipolar battery 40 shown in FIG. 1, and FIG. FIG. 4 is a cross-sectional view for explaining the single cell layer 26. FIG. 5 is a diagram showing in a stepwise manner the manufacturing process of the electrolyte layer 25 in which the seal portion 30 is formed on the separator 25a. FIG. 5 (A) schematically shows the separator 25a that forms the base material of the electrolyte layer 25. 5B is a schematic plan view showing a state in which the seal portion 30 is formed on the outer peripheral portion of the separator 25a, and FIG. 5C is a diagram showing the electrolyte portion 25b inside the seal portion 30 of the separator 25a. FIG. 5D is a schematic plan view showing a state in which the electrolyte layer 25 is formed and completed, and FIG. 5D is a cross-sectional view taken along line 5D-5D in FIG. 6A is a cross-sectional view of the main part showing a state in which the electrolyte layer 25 in which the seal portion 30 is formed on the separator 25a and the bipolar electrode 21 are laminated, and FIG. 6B is a cross-sectional view of the electrolyte layer 25 and the bipolar electrode 21. Is a cross-sectional view showing a state in which the battery element 20 is stacked from both sides along the stacking direction, and the seal portion 30 is brought into close contact with the current collector 22.

  Referring to FIG. 1 and FIG. 2, the battery module 11 of the first embodiment is roughly described. A battery element 20 in which a bipolar electrode 21 is stacked with an electrolyte layer 25 interposed therebetween, and a single battery layer in the battery element 20. A plurality of (four in the illustrated example) bipolar batteries 40 including a single battery layer 26 and a seal portion 30 that blocks contact between the single battery layer 26 and the outside air, and a direction in which the bipolar electrodes 21 are laminated. A pair of holding plates 50 and 60 having conductivity for sandwiching and holding a plurality of bipolar batteries 40 from both sides and electrically connecting the bipolar batteries 40 to each other are provided. In the plurality of bipolar batteries 40, the battery element 20 is directly sandwiched between a pair of holding plates 50 and 60. Here, “directly” means that there is no intervening packaging material that encloses and seals the entire battery element 20. It should be understood that the case where the elastic body 90 having conductivity described later is provided is also included in a form in which the battery element 20 is directly sandwiched between the pair of holding plates 50 and 60.

  In the first embodiment, the four bipolar batteries 40 are stacked in the direction in which the bipolar electrodes 21 are stacked (vertical direction in FIG. 1) and are electrically connected in series. This electrical connection form is referred to as “4 series”. The battery module 11 further includes a fastening member 70 that maintains a state in which a plurality of bipolar batteries 40 are sandwiched between a pair of holding plates 50 and 60, and a topmost bipolar battery via a holding plate 50 shown on the upper side in FIG. A positive electrode terminal 81 electrically connected to the positive electrode side of 40, and a negative electrode terminal 82 electrically connected to the negative electrode side of the lowest bipolar battery 40 via a holding plate 60 shown on the lower side in FIG. Have.

  In the following description, the holding plate 50 shown on the upper side in FIG. 1 is also referred to as “upper holding plate 50”, and the holding plate 60 shown on the lower side in FIG. 1 is also called “lower holding plate 60”. The direction in which the bipolar electrodes 21 are stacked, that is, the thickness direction of the battery is referred to as “stacking direction”, and the direction orthogonal to the stacking direction, that is, the direction in which the current collector 22 extends is referred to as “plane direction”.

  As shown in FIG. 3, the bipolar electrode 21 includes a positive electrode active material layer 23 disposed on one surface of a current collector 22 to form a positive electrode, and a negative electrode active material layer 24 disposed on the other surface. Is formed. The positive electrode terminal electrode of the battery element 20 is provided with only the positive electrode active material layer 23 on one surface of the current collector 22, and is laminated on the uppermost bipolar electrode 21 in FIG. 2 via the electrolyte layer 25. The negative electrode terminal electrode of the battery element 20 is provided with only the negative electrode active material layer 24 on one surface of the current collector 22, and is laminated under the lowest bipolar electrode 21 in FIG. The positive electrode end electrode and the negative electrode end electrode are also a kind of bipolar electrode 21. The electrolyte layer 25 is configured by holding an electrolyte in a separator 25a (see FIG. 5A) forming a base material.

  As shown in FIG. 4, the unit cell layer 26 is configured by laminating a positive electrode active material layer 23, an electrolyte layer 25, and a negative electrode active material layer 24. The single battery layer 26 is sandwiched between adjacent current collectors 22 in the battery element 20 in which the bipolar electrode 21 is laminated. The bipolar battery 40 in the example of FIG. 1 is provided with five cell layers 26, but the number of layers can be arbitrarily selected. The thickness of the bipolar battery 40 including the five single battery layers 26 is, for example, about 500 μm to 600 μm.

  The sealing part 30 blocks the contact between the unit cell layer 26 and the outside air. Thereby, the liquid junction by the liquid leakage which may arise when using a liquid or semi-solid gel electrolyte is prevented. In addition, the reaction between the air or moisture contained in the air and the active material is prevented. The seal portion 30 of the present embodiment is formed on the outer peripheral portion of the separator 25a of the electrolyte layer 25 (see FIG. 5D). The electrolyte layer 25 including the seal portion 30 is generally manufactured as follows.

  First, as a base material for the electrolyte layer 25, a separator 25a corresponding to the size used for the electrolyte layer 25 is prepared (see FIG. 5A). Next, a sealing resin 30a (solution) is disposed on the outer peripheral portion of the separator 25a to form the sealing portion 30 (see FIG. 5B). The outer peripheral portion of the separator 25a means the outside of the portion where the electrolyte is held by the separator 25a. The sealing resin 30a is disposed on the outer peripheral portion of the separator 25a by, for example, filling and pouring, applying or impregnating it using a mold having an appropriate shape. The seal part 30 is formed on both front and back surfaces of the separator 25a. The thickness (height) of the seal portion 30 protruding from both the front and back surfaces of the separator 25a is set to be larger than the thickness of the positive electrode and the thickness of the negative electrode. Next, the electrolyte is held by the separator 25a inside the seal portion 30 to form the electrolyte portion 25b (see FIGS. 5C and 5D). The electrolyte portion 25b is formed by an appropriate method such as a method of applying and impregnating an electrolyte raw material slurry to physically crosslink or further polymerize and chemically crosslink. As described above, the electrolyte is held in the separator 25a, and further, the electrolyte layer having a structure in which the sealing resin 30a forming the seal portion 30 is disposed on the portion of the separator 25a where the electrolyte is held, that is, the outer peripheral portion of the electrolyte portion 25b. 25 can be manufactured.

  As the separator 25a, any of a microporous membrane separator and a nonwoven fabric separator can be used.

  As the microporous membrane separator, for example, a porous sheet made of a polymer that absorbs and holds an electrolyte can be used. Examples of the polymer material include polyethylene (PE), polypropylene (PP), a laminate having a three-layer structure of PP / PE / PP, and polyimide.

  As the nonwoven fabric separator, for example, a sheet in which fibers are entangled can be used. In addition, a spunbond obtained by fusing fibers together by heating can also be used. In other words, it may be in the form of a sheet formed by arranging fibers in a web (thin cotton) shape or mat shape by an appropriate method, and joining them using an appropriate adhesive or the fusing force of the fibers themselves. The fibers to be used are not particularly limited, and conventionally known fibers such as cotton, rayon, acetate, nylon, polyester, polypropylene, polyethylene such as polyethylene, polyimide, and aramid can be used. These are used alone or in combination depending on the purpose of use (such as mechanical strength required for the electrolyte layer 25).

  The shape of the sealing resin 30a disposed on the outer periphery of the separator 25a is not particularly limited as long as it can effectively express the effect of sealing the single cell layer 26. For example, in addition to the rectangular cross section shown in FIG. 5D, the sealing resin 30a can be arranged so as to have a semicircular cross section or an elliptical cross section.

  The seal portion 30 obtained by disposing the sealing resin 30a desirably penetrates the separator 25a or covers the entire side surface of the separator 25a. This is because the contact between the single battery layer 26 and the outside air can be reliably blocked through the inside of the separator 25a.

  The sealing resin 30a may be a thermal resin such as a rubber resin that is in close contact with the current collector 22 by being deformed under pressure, or an olefin resin that is in close contact with the current collector 22 by being heat-pressed and heat-sealed. A resin that can be attached can be suitably used.

  In the illustrated example, a rubber-based resin is used as the sealing resin 30a. In the rubber-based seal portion 30 using the rubber-based resin, the contact between the unit cell layer 26 and the outside air can be blocked using the elasticity of the rubber-based resin. Further, even in an environment where stress due to vibration or impact is repeatedly applied to the bipolar battery 40, the rubber seal 30 is easily twisted or deformed following the twist or deformation of the bipolar battery 40. Can be held. Furthermore, there is no need to perform heat fusion treatment, which is advantageous in that the battery manufacturing process is simplified. The rubber resin is not particularly limited, but is preferably a rubber resin selected from the group consisting of silicon rubber, fluorine rubber, olefin rubber, and nitrile rubber. These rubber-based resins are excellent in sealing properties, alkali resistance, chemical resistance, durability / weather resistance, heat resistance, etc., and should be maintained for a long period of time without degrading their excellent performance and quality even in the use environment. Can do. Therefore, it is possible to prevent the contact between the unit cell layer 26 and the outside air, that is, the sealing of the unit cell layer 26 effectively and over a long period of time. However, it is not limited to the exemplified rubber-based resin.

  6A and 6B show how the rubber seal 30 is brought into close contact with the current collector 22. As shown in FIG. 6A, the electrolyte layer 25 in which the rubber seal 30 is formed and the bipolar electrode 21 are laminated on the separator 25a. The rubber-based seal portion 30 is molded so as to be thicker than the positive electrode or the negative electrode. Therefore, as shown in FIG. 6B, the battery element 20 in which the electrolyte layer 25 and the bipolar electrode 21 are stacked is pressed from both sides along the stacking direction, and the rubber seal 30 is pressed and deformed to collect current. Close contact with the body 22. In the present embodiment, when the rubber seal 30 is pressurized, heat is further applied. The rubber seal 30 is firmly bonded (adhered or fused) to the current collector 22 by heat-sealing in a state where the rubber seal 30 is pressure-deformed. This eliminates the need for the bipolar battery 40 to be constantly pressurized from the outside, and eliminates the need for a member for constantly pressing the rubber-based seal portion 30. The part to be pressurized may be the battery element 20 as a whole including the portion where the rubber seal 30 is disposed or the portion where the rubber seal 30 is disposed. In consideration of the influence on the battery parts other than the rubber-based seal portion 30 due to heating, the portion to be heated is only where the rubber-based seal portion 30 is disposed, and the portion where the rubber-based seal portion 30 material is disposed. Other than the above, it is desirable to perform only pressurization.

  Although not shown in the figure, in the heat-sealing resin-based seal portion using a heat-fusible resin, the battery element 20 in which the electrolyte layer 25 and the bipolar electrode 21 are laminated is pressurized and applied from both sides along the lamination direction. When heated, the contact between the unit cell layer 26 and the outside air can be blocked by heat fusion. The resin that can be heat-sealed is not particularly limited as long as it can exhibit an excellent sealing effect as a seal portion under any use environment of the bipolar battery 40. A resin selected from the group consisting of silicon, epoxy, urethane, polybutadiene, olefinic resins (polypropylene, polyethylene, etc.), and paraffin wax is preferable. These heat-sealable resins are excellent in sealing properties, alkali resistance, chemical resistance, durability / weather resistance, heat resistance, etc., and even in the usage environment, these excellent performance and quality are not deteriorated for a long time. Can be maintained. Therefore, it is possible to prevent the contact between the unit cell layer 26 and the outside air, that is, the sealing of the unit cell layer 26 effectively and over a long period of time. However, it is not limited to the exemplified heat-fusible resin. More preferably, a resin with improved adhesion to the current collector 22 is preferable, and examples thereof include modified polypropylene. The temperature condition for heating may be any temperature that is higher than the heat fusion temperature of the resin that can be heat-fused and does not affect other battery components. What is necessary is just to determine suitably according to the kind of resin. For example, about 200 ° C. is suitable for modified polypropylene and the like, but is not limited thereto. About the part to pressurize and the part to heat, it is the same as that of the case of the rubber-type seal part 30.

  The sealing part 30 can also be comprised from the three-layer film which pinched | interposed the non-fusion layer with the fusion | melting layer.

  The size of the seal portion 30 is not limited to a size that does not protrude from the end portion of the current collector 22 in the surface direction as shown in FIG. 6, and is a size that protrudes from the end portion of the current collector 22 in the surface direction. You may have. This is because an internal short circuit due to contact between the outer peripheral edges of the current collector 22 can be reliably prevented.

  The seal part can be arranged around the single cell layer independently of the electrolyte layer. In this case, however, the electrolyte layer and the seal part must be separately laminated when manufacturing the battery. However, the manufacturing process may be complicated or complicated. On the other hand, in this embodiment, since the seal part 30 is provided in the electrolyte layer 25, lamination | stacking of the electrolyte layer 25 and lamination | stacking of the seal part 30 can be performed simultaneously at the time of battery manufacture. As a result of not complicating the battery manufacturing process, the cost of the product can be reduced.

  Referring again to FIG. 1, in the first embodiment, the upper and lower holding plates 50 and 60 are both formed from conductive metal plates (conductive plates) 51 and 61. The conductive plates 51 and 61 are made of, for example, aluminum or stainless steel. Bolt holes 51 a and 61 a are formed in the upper and lower holding plates 50 and 60 in order to insert the through bolts 71. By fastening the nut 72 to the through bolt 71 inserted through each of the bolt holes 51a and 61a, the state where the plurality of bipolar batteries 40 are sandwiched between the upper and lower holding plates 50 and 60 is maintained. Since the upper and lower holding plates 50 and 60 are both conductive, the through bolt 71 and the nut 72 are made of an electrically insulating material. The through bolt 71 and the nut 72 constitute a fastening member 70 that maintains a state in which a plurality of bipolar batteries 40 are sandwiched by a pair of holding plates 50 and 60 and a pressing force is applied.

  The bipolar batteries 40 are in contact with each other through an elastic body 90 having conductivity. As described above, the positive electrode terminal electrode of the battery element 20 is provided with only the positive electrode active material layer 23 on one surface of the current collector 22, and the negative electrode terminal electrode has a negative electrode active material on one surface of the current collector 22. Only the layer 24 is provided, and the current collector 22 is disposed at the positive electrode end and the negative electrode end of each bipolar battery 40. Since the current collector 22 is formed from a metal foil, it has an uneven shape when viewed microscopically, and there is a possibility that the contact resistance between the current collectors 22 increases. Therefore, by bringing the bipolar batteries 40 into contact with each other via the conductive elastic body 90, the contact resistance between them is reduced.

  For the same reason, it is preferable that the upper and lower holding plates 50 and 60 and the bipolar battery 40 are brought into contact with each other through an elastic body 90 having conductivity. That is, since the upper and lower holding plates 50 and 60 are formed of a metal plate such as a stainless steel plate and the current collector 22 is formed of a metal foil, each surface has an uneven shape when viewed microscopically. The contact resistance between the holding plates 50 and 60 and the bipolar battery 40 may increase. Therefore, the upper and lower holding plates 50 and 60 and the bipolar battery 40 are brought into contact with each other via the conductive elastic body 90, thereby reducing the contact resistance between them.

  The conductive elastic body 90 will be described in more detail with reference to FIG. FIG. 7 is a cross-sectional view schematically showing the structure of the battery module of FIG. As shown in FIG. 7, the battery module 11 of the present embodiment is housed in the outer case 100. For example, as shown in FIG. 1, a pair of holding plates is secured by fastening a through bolt 71 and a nut 72. A plurality of bipolar batteries 40 are sandwiched between 50 and 60 and stored with a pressing force applied. Therefore, when a hard metal plate such as a conductive copper plate or aluminum plate is interposed between the bipolar batteries 40 and between the holding plates 50 and 60 and the bipolar battery 40, the corners of the plate ( Since the bipolar electrode 40 may be short-circuited by the edge), it is necessary to use a soft material. In addition, since the current collector 22 on the surface of the bipolar battery 40 has irregularities of ± 50 μm at the maximum, a hard conductive metal plate increases the contact resistance.

  Therefore, it is preferable to use a conductive material having a softness that can absorb irregularities on the surface of the bipolar battery 40. In the present invention, the elastic modulus of the conductive material suitable for connecting the bipolar battery 40 is defined. Tried. Further, by using a material having a low elastic modulus, it is possible to configure a structure that can withstand vibration when the battery module 11 is mounted on a vehicle.

FIG. 8 is a diagram used for examining the elastic modulus of the elastic body 90 having conductivity in the present embodiment. In FIG. 8, the pressing force is 1.0 × 10 ^{3 to} 1.0 × 10 ⁵ Pa, the unevenness of the current collector 22 on the surface of the bipolar battery is 50 μm, and the thickness of the elastic body 90 is 0.5 to 1. Consider a case where the elastic body 90 is 0 mm and the elastic body 90 is desired to be reduced by a maximum of 100 μm.

That is, the minimum elastic modulus is defined by the surface unevenness of the current bipolar battery and the minimum pressing force of 1.0 × 10 ³ Pa.

1.0 × 10 ³ Pa × (0.1 / 0.1) = 1.0 × 10 ³ Pa
Further, the maximum elastic modulus is defined by the surface unevenness of the target bipolar battery and the maximum pressing force of 1.0 × 10 ⁵ Pa.

1.0 × 10 ⁵ Pa × (3.0 / 0.04) = 7.5 × 10 ⁶ Pa
Based on such examination, the pressing force by the pair of holding plates 50 and 60 is 1.0 × 10 ^{3 to} 1.0 × 10 ⁵ Pa, and the thickness of the elastic body 90 is 0.1 mm to 3.0 mm. In that case, the elastic modulus of the elastic body 90 is preferably 1.0 × 10 ^{3 to} 7.5 × 10 ⁶ Pa.

  Examples of the material satisfying this elastic modulus and conductivity (electronic conductivity) include a conductive rubber sheet or a graphite sheet.

  When holding the plurality of bipolar batteries 40 by the upper and lower holding plates 50, 60, it is preferable to use a conductive rubber sheet as the elastic body 90 having conductivity. By using a conductive rubber sheet, adhesion, protection of the current collector foil, vibration resistance, absorption of changes in thickness due to temperature changes, and the like can be expected. The conductive rubber sheet is a conductive resin in which carbon or metal fine particles are dispersed in a resin, or a conductive plastic.

  Specifically, as the conductive rubber, silicon rubber, fluorine rubber, epichlorohin rubber, acrylic rubber, ethylene acrylic rubber, urethane rubber, nitrile rubber, hydrogenated nitrile rubber, chlorosulfonated polyethylene, chloroprene rubber, terbrene (EPDM), ethylene rubber, propylene rubber, butyl rubber, butadiene rubber, styrene butadiene rubber, natural rubber, or isoprene rubber.

  When these elastic bodies 90 enter into the minute recesses of the current collector 22 and the holding plates 50 and 60 by the elastic force, they are between the bipolar batteries 40 and between the holding plates 50 and 60 and the bipolar battery 40. Good adhesion. The elastic body 90 having conductivity may have a form of a double-sided tape, for example. As a result of good adhesion between the elastic body 90 having conductivity and the current collector 22 or the holding plates 50, 60 having minute irregularities, the contact resistance is reduced and the output of the battery module 11 is increased. Can do.

  In FIG. 1, for the sake of easy understanding, the elastic body 90 having conductivity protrudes from the end portion of the bipolar battery 40 in the plane direction, but is not limited to this case. As described above, it may be formed so as not to protrude from the end of the bipolar battery 40.

  In the first embodiment, since the bipolar battery 40 is provided with the seal portion 30 that blocks the contact between the unit cell layer 26 and the outside air, there is no need to seal the battery element 20 with an exterior material. The bipolar battery 40 is directly sandwiched between a pair of holding plates 50 and 60. When the battery module 11 is formed, a series of operations for forming the battery module 11 using the bipolar battery 40 can be simplified by eliminating the need to seal the individual battery elements 20 with an exterior material. . Further, the plurality of bipolar batteries 40 are electrically connected only by sandwiching and holding the plurality of bipolar batteries 40 by the upper and lower holding plates 50 and 60. When the plurality of bipolar batteries 40 are electrically connected, there is no need to join the current extraction terminals by welding or connect them via a connecting member such as a bus bar. From this viewpoint, a series of operations for forming the battery module 11 can be simplified. Since the bipolar batteries 40 are connected directly or via the conductive elastic body 90 without interposing a current extraction terminal, the output of the battery module 11 can be increased. Since the exterior material and the terminal for taking out the current are not necessary, the volume of the battery module 11 can be reduced accordingly. Further, since the upper and lower holding plates 50 and 60 are both conductive, it is possible to take out current only by sandwiching and holding a plurality of bipolar batteries 40, and the structure for taking out current can be simplified. As described above, the battery module 11 has a structure that takes advantage of the bipolar battery 40 that current flows in the stacking direction in the battery element 20, and the battery module 11 using the bipolar battery 40 can be easily formed. It becomes.

  Since the plurality of bipolar batteries 40 are electrically connected in series, it is possible to easily meet the demand for output simply by changing the number of series-connected batteries.

  The configuration of the bipolar battery 40 may be any known material used for a general lithium ion secondary battery, except for those specifically described, and is not particularly limited. Hereinafter, a current collector, a positive electrode active material layer, a negative electrode active material layer, an electrolyte layer, and the like that can be used for the bipolar battery 40 will be described for reference.

(Current collector)
The current collector that can be used in the present embodiment is not particularly limited, and a conventionally known current collector can be used. For example, aluminum foil, stainless steel foil, nickel-aluminum clad material, copper-aluminum clad material, or a plating material of a combination of these metals can be preferably used. Further, a current collector in which a metal surface is coated with aluminum may be used. Moreover, you may use the electrical power collector which bonded 2 or more metal foil depending on the case. From the viewpoint of corrosion resistance, ease of production, economy, etc., it is preferable to use an aluminum foil as a current collector.

  The thickness of the current collector is not particularly limited, but is about 1 μm to 100 μm.

(Positive electrode active material layer)
The positive electrode includes a positive electrode active material. In addition to this, a conductive aid, a binder, and the like may be included. The gel electrolyte is sufficiently infiltrated into the positive electrode and the negative electrode by chemical crosslinking or physical crosslinking.

As the positive electrode active material, a composite oxide of transition metal and lithium, which is also used in a solution-type lithium ion battery, can be used. Specifically, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, Li · Mn-based composite oxide such as spinel LiMn ₂ O _4, Li · such LiFeO ₂ Examples thereof include Fe-based composite oxides. In addition, transition metal and lithium phosphate compounds and sulfuric acid compounds such as LiFePO ₄ ; transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ ; PbO ₂ , AgO, NiOOH etc. are mentioned.

  The particle size of the positive electrode active material is not limited as long as it can be formed into a paste by spraying the positive electrode material and spray coating or the like, but in order to further reduce the electrode resistance of the bipolar battery, the electrolyte is not a solid solution type What is smaller than the generally used particle size used in the lithium ion battery of the present invention may be used. Specifically, the average particle diameter of the positive electrode active material is preferably 0.1 μm to 10 μm.

  The polymer gel electrolyte is a solid polymer electrolyte having ion conductivity containing an electrolyte solution usually used in a lithium ion battery. Further, in the polymer skeleton having no lithium ion conductivity, In addition, those holding the same electrolytic solution are also included.

Here, the electrolyte solution (electrolyte salt and plasticizer) contained in the polymer gel electrolyte may be any electrolyte solution that is normally used in lithium ion batteries. For example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF. ₆ , inorganic acid anion salts such as LiAlCl ₄ and Li ₂ B ₁₀ Cl ₁₀ , organic acid anions such as LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, and Li (C ₂ F ₅ SO ₂ ) ₂ N Including at least one lithium salt (electrolyte salt) selected from ionic salts, cyclic carbonates such as propylene carbonate and ethylene carbonate; chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane Ethers such as 1,2-dimethoxyethane and 1,2-dibutoxyethane; Lactones such as γ-butyrolactone; Nitriles such as acetonitrile; Esters such as methyl propionate; Amides such as dimethylformamide; Methyl acetate Further, those using an organic solvent (plasticizer) such as an aprotic solvent in which at least one selected from methyl formate or a mixture of two or more thereof can be used. However, it is not necessarily limited to these.

  Examples of the polymer having ion conductivity include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.

  For example, polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), etc. are used as the polymer having no lithium ion conductivity used for the polymer gel electrolyte. it can. However, it is not necessarily limited to these. Note that PAN, PMMA, etc. are in a class that has almost no ionic conductivity. Therefore, the PAN, PMMA, and the like can be used as a polymer having the ionic conductivity described above, but are used here as a polymer gel electrolyte. This is exemplified as a polymer having no lithium ion conductivity.

As the lithium salt, for _{example, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 Cl 10 and the like inorganic acid anion _{salts, Li (CF 3 SO 2)} 2 N, An organic acid anion salt such as Li (C ₂ F ₅ SO ₂ ) ₂ N or a mixture thereof can be used. However, it is not necessarily limited to these.

  Examples of the conductive assistant include acetylene black, carbon black, and graphite. However, it is not necessarily limited to these.

  In this embodiment, these electrolyte solution, lithium salt, and polymer (polymer) are mixed to prepare a pregel solution, and the positive electrode and the negative electrode are impregnated.

  The blending amount of the positive electrode active material, the conductive additive, and the binder in the positive electrode should be determined in consideration of the intended use of the battery (emphasis on output, energy, etc.) and ion conductivity. For example, if the amount of the electrolyte in the positive electrode, particularly the solid polymer electrolyte, is too small, the ionic conduction resistance and the ionic diffusion resistance in the active material layer will increase and the battery performance will deteriorate. On the other hand, when the amount of the electrolyte in the positive electrode, particularly the solid polymer electrolyte, is too large, the energy density of the battery decreases. Therefore, in consideration of these factors, the solid polymer electrolytic mass meeting the purpose is determined.

  The thickness of the positive electrode is not particularly limited, and should be determined in consideration of the intended use of the battery (emphasis on output, emphasis on energy, etc.) and ion conductivity, as described for the blending amount. A typical positive electrode active material layer has a thickness of about 10 to 500 μm.

(Negative electrode active material layer)
The negative electrode includes a negative electrode active material. In addition to this, a conductive aid, a binder, and the like may be included. Since the contents other than the type of the negative electrode active material are basically the same as the contents described in the section “Positive electrode”, the description is omitted here.

  As the negative electrode active material, a negative electrode active material that is also used in a solution-type lithium ion battery can be used. For example, metal oxide, lithium-metal composite oxide metal, carbon and the like are preferable. More preferred are carbon, transition metal oxide, and lithium-transition metal composite oxide. More preferred are titanium oxide, lithium-titanium composite oxide, and carbon. These may be used alone or in combination of two or more.

  In this embodiment, the positive electrode active material layer uses lithium-transition metal composite oxide as the positive electrode active material, and the negative electrode active material layer uses carbon or lithium-transition metal composite oxide as the negative electrode active material. Is used. This is because a battery having excellent capacity and output characteristics can be configured.

(Electrolyte layer)
The electrolyte layer is a layer composed of a polymer having ion conductivity, and the material is not limited as long as it exhibits ion conductivity.

  The electrolyte of this embodiment is a polymer gel electrolyte, and is used as a polymer gel electrolyte by chemical crosslinking or physical crosslinking after impregnating a pregel solution into a separator as a base material.

  Such a polymer gel electrolyte is an all-solid polymer electrolyte having ion conductivity such as polyethylene oxide (PEO) containing an electrolytic solution usually used in a lithium ion battery. A polymer gel electrolyte that contains a similar electrolyte solution in a polymer skeleton having no lithium ion conductivity such as vinylidene (PVDF) is also included. Since these are the same as the polymer gel electrolyte described as a kind of electrolyte contained in the positive electrode, description thereof is omitted here. The ratio of the polymer and the electrolyte constituting the polymer gel electrolyte is wide. When 100% of the polymer is an all-solid polymer electrolyte and 100% of the electrolyte is a liquid electrolyte, all of the intermediates correspond to the polymer gel electrolyte. The term “polymer electrolyte” includes both a polymer gel electrolyte and an all solid polymer electrolyte.

  The polymer gel electrolyte can be contained in the positive electrode and / or the negative electrode as described above in addition to the polymer electrolyte constituting the battery, but uses a polymer electrolyte that differs depending on the polymer electrolyte constituting the battery, the positive electrode, and the negative electrode. Alternatively, the same polymer electrolyte may be used, or different polymer electrolytes may be used depending on the layer.

  The thickness of the electrolyte constituting the battery is not particularly limited. However, in order to obtain a compact bipolar battery, it is preferable to make it as thin as possible as long as the function as an electrolyte can be secured. The thickness of a general solid polymer electrolyte layer is about 10 to 100 μm. However, the shape of the electrolyte can be easily formed so as to cover the upper surface of the electrode (positive electrode or negative electrode) as well as the outer periphery of the side surface, taking advantage of the characteristics of the manufacturing method. It is not always necessary to have a substantially constant thickness.

  A solid electrolyte can also be used for the electrolyte layer. This is because by using a solid as the electrolyte, it is possible to prevent liquid leakage, preventing a liquid junction that is a problem peculiar to bipolar batteries, and providing a highly reliable bipolar battery. Moreover, since there is no liquid leakage, the structure of the seal part 30 can be simplified.

Examples of the solid electrolyte include known solid polymer electrolytes such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. The solid polymer electrolyte layer contains a supporting salt (lithium salt) in order to ensure ionic conductivity. As the supporting salt, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , or a mixture thereof can be used. However, it is not necessarily limited to these. Polyalkylene oxide polymers such as PEO and PPO can dissolve lithium salts such as LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) ₂ well. Moreover, excellent mechanical strength is exhibited by forming a crosslinked structure.

(Second Embodiment)
Referring to FIG. 9, in the battery module 13 of the second embodiment, two battery groups in which two bipolar batteries 40 are stacked in the vertical direction and electrically connected in series are arranged in the stacking direction of the bipolar electrodes 21. Are arranged in a direction orthogonal to the. In addition, the two battery groups are arranged so that the electric polarities are the same (the upper side in the figure is the positive side and the lower side is the negative side), and are electrically connected in parallel via the upper and lower holding plates 50 and 60. Has been. This electrical connection form is referred to as “2 parallel × 2 series”.

  In the second embodiment, since a plurality of bipolar batteries 40 are electrically connected in series and parallel, the output and capacity requirements can be met only by changing the number connected in series and the number connected in parallel. It can respond easily.

(Third embodiment)
The battery modules 11 (13) described above are connected in series or in parallel to form an assembled battery module 250 (see FIG. 10), and a plurality of the assembled battery modules 250 are connected in series or in parallel. Thus, the assembled battery 300 can also be formed. The assembled battery module 250 shown in the figure is obtained by stacking a plurality of the battery modules 11 and storing them in a module case, and connecting the battery modules 11 in parallel. FIG. 10 shows a plan view (FIG. A), a front view (FIG. B), and a side view (FIG. C) of an assembled battery 300 according to the third embodiment of the present invention. Are connected to each other using an electrical connection means such as a bus bar, and the assembled battery module 250 is stacked in a plurality of stages using a connection jig 310. How many battery modules 11 are connected to create the assembled battery module 250, and how many assembled battery modules 250 are stacked to create the assembled battery 300 depends on the vehicle (electric vehicle) to be mounted. It may be determined according to the battery capacity and output.

  According to the third embodiment, a battery with high capacity and high output can be obtained by connecting the battery modules 11 in parallel to form an assembled battery. In addition, each of the battery modules 11 using the bipolar battery 40 has a structure that takes advantage of the bipolar battery 40 that the current flows in the stacking direction in the battery element 20 and can be easily formed. Through this, it becomes easy to form a battery pack 300 in which a plurality of battery modules 11 are electrically connected. Further, since the battery module 11 has a long life and high reliability, the assembled battery 300 also has a long life and high reliability. Further, even if some of the assembled battery modules 250 fail, repair can be performed by simply replacing the failed part.

(Fourth embodiment)
FIG. 11 is a schematic configuration diagram showing an automobile 400 as a vehicle according to the fourth embodiment of the present invention. The battery module 11 (13) and / or the assembled battery 300 described above can be mounted on a vehicle such as an automobile or a train and used as a power source for driving an electric device such as a motor. As described above, since the battery module 11 and the assembled battery 300 can be easily formed, it is easy to form a driving power source mounted on the vehicle.

  In order to mount the assembled battery 300 on the electric vehicle 400, the battery pack 300 is mounted under the seat at the center of the vehicle body of the electric vehicle 400 as shown in FIG. This is because if it is installed under the seat, the interior space and the trunk room can be widened. The place where the assembled battery 300 is mounted is not limited to the position under the seat, but may be a lower part of the rear trunk room or an engine room in front of the vehicle. The electric vehicle 400 using the assembled battery 300 as described above has high durability and can provide sufficient output even when used for a long period of time. Furthermore, it is possible to provide electric vehicles and hybrid vehicles that are excellent in fuel efficiency and driving performance.

  In the present invention, not only the assembled battery 300 but also only the assembled battery module 250 may be mounted depending on the usage, or the assembled battery 300 and the assembled battery module 250 may be mounted in combination. Also good. Further, as the vehicle on which the assembled battery or the assembled battery module of the present invention can be mounted, the above-described electric vehicle and hybrid car are preferable, but are not limited thereto.

It is sectional drawing which shows the laminated structure of the battery module which concerns on 1st Embodiment. It is sectional drawing which shows a bipolar battery. It is sectional drawing which shows a bipolar electrode. It is sectional drawing with which it uses for description of a cell layer. It is a figure showing the mode of the manufacturing process of the electrolyte layer which formed the seal part in the separator in steps. FIG. 6A is a cross-sectional view of a principal part showing a state in which an electrolyte layer having a separator formed on a separator and a bipolar electrode are laminated, and FIG. 6B is a battery element in which the electrolyte layer and the bipolar electrode are laminated. It is sectional drawing which shows a mode that this is pressurized from the both sides along a lamination direction, and a seal | sticker part is closely_contact | adhered to a collector. It is sectional drawing which shows the structure of the battery module of FIG. 1 typically. It is a figure used for examination of elastic modulus. It is sectional drawing which shows the laminated structure of the battery module which concerns on 2nd Embodiment. It is a schematic block diagram of the assembled battery which concerns on 3rd Embodiment. It is a figure which shows the state with which the assembled battery which concerns on 4th Embodiment was mounted in the vehicle.

Explanation of symbols

11 battery modules,
20 power generation elements,
21 bipolar electrodes,
22 current collector,
23 positive electrode active material layer,
24 negative electrode active material layer,
25 electrolyte layer,
25a separator,
26 cell layer,
30 seal part,
40 bipolar battery,
50 positive tab,
51, 61 electrode takeout part,
60 negative electrode tab,
90 an elastic body having conductivity,
100 exterior case,
250 battery module,
300 battery packs,
310 connection jig,
400 vehicles.

Claims (9)

A battery element in which a bipolar electrode having a positive electrode layer disposed on one surface of a current collector and a negative electrode layer disposed on the other surface is laminated with an electrolyte layer interposed therebetween, and the positive electrode layer, the electrolyte layer, and the negative electrode layer include A plurality of bipolar batteries including a seal portion disposed around each of the stacked unit cell layers and blocking contact between the unit cell layers and outside air;
A pair of conductive holding plates that sandwich and hold a plurality of the bipolar batteries from both sides along the direction in which the bipolar electrodes are stacked and electrically connect the bipolar batteries; and
The plurality of bipolar batteries are contacted via an elastic body having conductivity,
The battery module, wherein an elastic modulus of the elastic body is 1.0 × 10 ^{3 to} 7.5 × 10 ⁶ Pa.   2. The battery module according to claim 1, wherein the plurality of bipolar batteries are sandwiched with a pressing force applied by the pair of holding plates. The thickness of the elastic body is 0.1 mm to 3.0 mm, and the pressing force by the pair of holding plates is 1.0 × 10 ^{3 to} 1.0 × 10 ⁵ Pa. Or the battery module of Claim 2.   The battery module according to claim 1, wherein the holding plate is made of a conductive metal plate.   The battery module according to any one of claims 1 to 4, wherein the holding plate and the bipolar battery are in contact with each other through the conductive elastic body.   The battery module according to any one of claims 1 to 5, wherein the elastic body is a conductive rubber sheet or a graphite sheet.   The conductive rubber is silicon rubber, fluorine rubber, epichlorohin rubber, acrylic rubber, ethylene acrylic rubber, urethane rubber, nitrile rubber, hydrogenated nitrile rubber, chlorosulfonated polyethylene, chloroprene rubber, terbrene, (EPDM), 7. The battery module according to claim 6, wherein the battery module is ethylene rubber, propylene rubber, butyl rubber, butadiene rubber, styrene butadiene rubber, natural rubber or isoprene rubber.   A battery pack comprising a plurality of battery modules according to claim 1 connected to each other.   A vehicle comprising the battery module according to claim 1 or the assembled battery according to claim 8 as a power source.

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