JP4341427B2 - Bipolar battery - Google Patents

Description

  The present invention relates to a bipolar battery. In particular, the present invention relates to an improved means for measuring the voltage of a single cell of a bipolar battery.

  In recent years, in order to cope with air pollution and global warming, reduction of the amount of carbon dioxide has been strongly desired. In the automobile industry, there is a great expectation for reducing carbon dioxide emissions by introducing electric vehicles (EV) and hybrid electric vehicles (HEV), and the development of secondary batteries for motor drive that holds the key to commercialization of these is thriving. Has been done.

  As a secondary battery for driving a motor, a lithium ion secondary battery having the highest theoretical energy among all the batteries is attracting attention, and is currently being developed rapidly. When using a lithium ion secondary battery, usually, a plurality of battery modules are connected in series to form a battery module, and further, a battery pack is formed by connecting the battery modules in series to obtain a high energy density. Yes. However, such an assembled battery has a problem in that the resistance due to the connection between the batteries and the connection between the battery modules is added, the internal resistance of the entire assembled battery at the time of charging and discharging is increased, and high output density cannot be obtained. .

  As a means for solving the above problem, a battery element in which a plurality of bipolar electrodes each having a positive electrode layer formed on one surface of a current collector and a negative electrode layer formed on the other surface are stacked via an electrolyte layer. There has been proposed a bipolar lithium ion secondary battery (also referred to simply as “bipolar battery” in this specification) (see, for example, Patent Document 1). In other words, the battery element of the bipolar battery has a configuration in which a plurality of single cells are connected in series.

  In a bipolar battery having such a configuration, even when the same unit cells are stacked to form a battery element, the voltage of each unit cell is not necessarily constant and may vary. If the voltage of each unit cell varies, there is a risk that the unit cell having a high voltage will deteriorate during use and may be damaged.

  Here, in a bipolar battery, once the cells are stacked and the battery elements are formed, the total voltage of all the cells can be measured, but the voltage between the positive and negative electrodes of each cell is measured. It is difficult to do.

In order to solve this problem, in Patent Document 2, each unit cell is manufactured first, and a bipolar cell is manufactured by stacking the unit cells. As a result, the voltage and capacity of each unit cell can be checked, and if there is a defective battery unit, it can be removed when the battery is manufactured.
Japanese Utility Model Publication No. 4-54148 JP-A-11-204136

  However, the bipolar battery described in Patent Document 2 can check the voltage of each unit cell at the time of manufacture, but it is still difficult to measure the voltage of each unit cell once the battery element is formed. It is. For this reason, when a malfunction occurs in any single cell after the formation of the battery element, this cannot be detected. As a result, the deterioration of some of the unit cells may progress, and characteristics such as the capacity and life of the entire battery may be reduced.

  Therefore, an object of the present invention is to provide means for measuring the voltage of each single cell even after the formation of the battery element in the bipolar battery.

The present invention relates to a bipolar battery in which a battery element in which a plurality of unit cells are connected in series via a current collector is enclosed in a battery outer package, and the unit cell is sandwiched between the unit cells. A voltage measurement lead made of a flexible flat cable in which a conductor is covered with an insulating film for measuring the voltage of each is connected and led out of the battery exterior body. At this time, the voltage measurement lead In the lead-out part, the insulating film is sandwiched between the battery casings.

  In the present invention, a voltage measuring lead for measuring the voltage of each unit cell is connected to the unit cell constituting the battery element of the bipolar battery. As a result, the voltage of each unit cell can be measured even after the battery element is formed. For this reason, the bipolar battery of the present invention is particularly useful when mounted on a vehicle or the like in which it is not easy to measure the voltage of each single battery after it is once mounted.

  A first aspect of the present invention is a bipolar battery in which a battery element in which a plurality of unit cells are connected in series is enclosed in a battery outer package, and a current for each unit cell is connected to a current collector sandwiching the unit cell. A bipolar battery is characterized in that a voltage measuring lead made of a flexible flat cable is connected to measure the voltage.

  Hereinafter, the bipolar battery of the present invention will be described in detail. In the present invention, except that a voltage measurement lead made of a flexible flat cable (abbreviated as “FFC” in the present specification) is connected to a current collector that sandwiches a single battery, The materials used for the bipolar batteries can be used as well. For this reason, although a positive electrode layer, an electrolyte layer, a negative electrode layer, a tab, a battery exterior body, etc. are demonstrated easily, these forms are not necessarily limited to the illustrated material and shape. Newly developed materials and shapes may also be used.

  Here, the FFC will be briefly described with reference to the drawings.

  The “flexible flat cable (FFC)” is a cable 1 as shown in FIGS. 1 and 2, for example. FIG. 1 is a plan view showing a preferred embodiment of the FFC. FIG. 2 is a schematic perspective view showing a preferred embodiment of the FFC.

  That is, FFC means a cable 1 in which both surfaces of a conductor 2 wired in parallel are covered with an insulating film 3 as shown in FIGS. The FFC 1 can be easily connected to another conductor by exposing the conductor 2 by peeling the insulating film 3 at the tip. In some cases, as shown in FIGS. 1 and 2, the insulating film 3 is provided with a thin-walled portion 4, and the FFC can be cut for each conductor or a plurality of conductors. The form of FFC is not limited to the form shown in FIGS. In addition, these drawings are exaggerated for convenience of explanation, and the ratios of the thicknesses and widths of the respective constituent components may be different from actual ones. The same applies to the following drawings.

(First embodiment)
Hereinafter, the configuration and effects of the first embodiment will be briefly described.

  First, a general configuration of a bipolar battery will be described with reference to FIGS. 3 and 4. FIG. 3 is a schematic perspective view showing the appearance of the bipolar battery according to the first embodiment. FIG. 4 is a schematic cross-sectional view along the line AA shown in FIG. 3 and 4 are for illustrative purposes, and the configuration of the bipolar battery is not limited to the configuration shown in FIGS. 3 and 4.

  As shown in FIG. 4, the bipolar battery 11 has a bipolar electrode in which a positive electrode layer 15 is formed on one surface of a current collector 13 and a negative electrode layer 17 is formed on the other surface of the current collector 13. The battery element 21 is formed by stacking a plurality of layers through the electrolyte layer 19. In other words, in the battery element 21, the unit cell 23 in which the electrolyte layer 19 is sandwiched between the positive electrode layer 15 and the negative electrode layer 17 is laminated. In the battery element 21, a current collector (also referred to as “positive electrode outermost current collector”) 25 arranged in the outermost layer on the positive electrode side includes only the positive electrode layer 15, and the outermost current collector on the negative electrode side. A current collector (also referred to as “negative electrode outermost layer current collector”) 27 disposed in the outer layer has only the negative electrode layer 17. Further, a positive electrode tab 29 and a negative electrode tab 31 for taking out current to the outside are joined to the outermost layer current collectors 25 and 27 (see FIG. 3). Further, as shown in FIG. 3, the battery element 21 is enclosed in a battery outer package 33 such that the positive electrode tab 29 and the negative electrode tab 31 are exposed to the outside. In some cases, an insulating layer 35 may be provided between adjacent current collectors 13 for the purpose of preventing a short circuit (liquid junction) between the current collectors 13.

  In the conventional bipolar battery, generally, only the positive electrode tab and the negative electrode tab are exposed to the outside of the battery outer package. For this reason, the voltage for every single cell cannot be measured after the battery element is formed, and this cannot be detected if any single cell has a problem after the battery element is formed. As a result, the deterioration of some of the unit cells may progress, and characteristics such as the capacity and life of the entire battery may be reduced.

  In order to measure the voltage of each unit cell, a means of connecting a cable to each current collector and leading it out of the battery outer package is also conceivable. However, in general, the cable is thick. For this reason, if a cable is used as a voltage measurement means for each cell, the distance between the electrodes increases due to the cable connected to the current collector, causing distortion of the battery, and eventually the capacity and life of the battery. Such as performance will be reduced.

  On the other hand, in the bipolar battery 11 of the present invention, as described above, the voltage measurement lead 37 made of FFC is connected to each current collector 13. By adopting such a voltage measurement lead 37, the voltage of each single cell 23 can be measured even after the battery element 21 is formed without affecting the shape of the battery. As a result, it is possible to detect the presence of a defective unit cell 23 that occurs after the formation of the battery element 21, and to improve battery characteristics such as capacity and life of the entire bipolar battery 11.

  Hereinafter, a preferred embodiment in which the voltage measurement lead is connected to the current collector will be described in detail with reference to the drawings.

  FIG. 5 is a schematic perspective view showing the battery element in the first embodiment of the present invention. FIG. 6 is a side view showing the connection positions of the voltage measurement leads in the first embodiment of the present invention as seen from the direction of the arrow X shown in FIG. In the battery element 21 shown in FIGS. 5 and 6, the current collector, the electrode, the electrolyte layer, and the like that are members constituting the battery element 21 are omitted. The same applies to the following drawings showing battery elements.

  In the present invention, a voltage measuring lead 37 made of FFC for measuring the voltage of each unit cell 23 is connected to the current collector 13 sandwiching the unit cell 23, and as shown in FIGS. 3 and 4. In addition, the voltage measurement lead 37 is also led out of the battery exterior body 33.

  Specifically, in the battery element 21 in the first embodiment, as shown in FIGS. 5 and 6, voltage measuring leads 37 a to 37 h made of FFC are provided on the current collectors 13 sandwiching the unit cell 23. The battery elements 21 are connected so as to be shifted in the longitudinal direction of the side surfaces of the battery elements 21 so as not to overlap each other in a stacked state. By connecting the voltage measurement leads 37 in such a form, the risk of the voltage measurement leads 37 coming into contact with each other and short-circuiting can be reduced.

  Here, since the voltage measurement lead 37 is made of FFC, in some cases, the tip of the resin part is partially cut along the thin part provided in the resin part of the FFC, and the exposed conductor It is also possible to connect to a current collector. That is, in such a case, since the resin portion is not cut at the front end portion of the FFC on the side not connected to the current collector, each conductor remains in a straight line at equal intervals. As a result, there is an advantage that the structure of the voltage measuring socket for measuring the voltage of the unit cell 23 by connecting to the voltage measuring lead 37 made of FFC is simplified and the manufacture thereof is facilitated. If necessary for manufacturing, as shown in FIG. 3, the FFC may be connected to the current collector after being cut into a single piece or a plurality of pieces by a thin portion provided in the resin portion. Of course.

  There is no particular limitation on the specific form in which the voltage measurement lead 37 made of FFC is connected to the current collector 13. Hereinafter, embodiments other than the first embodiment described above will be described in more detail. The following embodiment is also for illustration as in the first embodiment, and the technical scope of the present invention is not limited to this embodiment.

(Second Embodiment)
FIG. 7 is a schematic perspective view showing the appearance of the bipolar battery according to the second embodiment. FIG. 8 is a schematic cross-sectional view along the line AA shown in FIG. FIG. 9 is a schematic perspective view showing a battery element in the second embodiment of the present invention. FIG. 10 is a side view showing the connection position of the voltage measurement lead in the second embodiment of the present invention as seen from the direction of the arrow X shown in FIG. FIG. 11 is a side view showing the connection position of the voltage measurement lead in the second embodiment of the present invention as seen from the direction of the arrow Y shown in FIG.

  As shown in FIGS. 7 to 11, the bipolar battery according to the second embodiment is different from the first embodiment described above except that the voltage measurement lead 37 made of FFC is connected to each current collector 13. This is basically the same as the bipolar battery of the embodiment. Therefore, hereinafter, a detailed description will be given focusing on a mode in which the voltage measurement lead 37 is connected to the current collector 13 in the second embodiment.

  As shown in FIGS. 9 to 11, in the second embodiment, the voltage measuring leads 37 a to 37 b connected to the four current collectors 13 from the top of the battery element 21 having the eight current collectors 13. 37 d is connected to one side surface of the battery element 21 so as not to overlap each other in a stacked state, shifted in the longitudinal direction of the surface. On the other hand, the voltage measurement leads 37e to 37h connected to the four current collectors 13 from the bottom of the battery element 21 are shifted on the other side surface of the battery element 21 in the longitudinal direction of the surface and stacked. Connected so as not to overlap each other. Therefore, also in the second embodiment, when the voltage measurement leads 37 are connected in such a manner, the risk that the voltage measurement leads 37 contact each other and short-circuit can be reduced.

  Moreover, in the bipolar battery 11 of the second embodiment, the voltage measuring leads 37a to 37d connected to the four current collectors 13 from the top of the battery element 21 are connected to the battery as shown in FIGS. It passes through the upper part of the element 21 and is led out of the battery exterior body 33 from the same side as the voltage measurement leads 37 e to 37 h connected to the four current collectors 13 from below the battery element 21. As described above, it is preferable that the voltage measurement lead 37 made of FFC connected to the current collector 13 passes through the upper part and / or the lower part of the battery element 21 and is led out of the battery exterior body 33. In other words, the voltage measurement lead 37 is preferably led out of the battery outer package 33 from the side opposite to the side connected to the current collector 13. In the bipolar battery of the present invention, the upper part and the lower part of the battery element mean the upper part and the lower part when the stacking direction of the battery elements is the vertical direction. At this time, either the outermost layer current collector for positive electrode or the outermost layer current collector for negative electrode may be present in the upper part.

  Hereinafter, the effect obtained by the voltage measurement lead 37 passing through the upper part and / or the lower part of the battery element 21 and being led out of the battery exterior body 33 will be described in detail.

  For example, when a bipolar battery is mounted on a vehicle such as an automobile, it is required to supply power stably over a long period of time under conditions of severe vibration. However, when exposed to a vibration state for a long period of time, there is a problem that the active material of the electrode is peeled off and the performance such as the capacity and life of the battery is lowered.

  On the other hand, as in the second embodiment of the present invention, the voltage measurement lead 37 made of FFC is passed through the upper part and / or the lower part of the battery element 21 and led out of the battery outer body 33, It is possible to improve resistance to vibration load. This is because the resin part of the FFC that passes through the upper part and / or the lower part of the battery element 21 absorbs the vibration and the transmission of the vibration to the battery element 21 is suppressed. As shown in FIGS. 8 and 9, the FFC is generally extremely thin and flexible, and therefore has a high degree of freedom in attachment. In the present invention, such an FFC is employed as the voltage measurement lead 37, thereby enabling wiring as in the second embodiment.

(Third embodiment)
FIG. 12 is a schematic perspective view showing the appearance of the bipolar battery according to the third embodiment. FIG. 13 is a schematic cross-sectional view along the line AA shown in FIG. FIG. 14 is a schematic perspective view showing a battery element in the third embodiment of the present invention. FIG. 15 is a side view showing the connection position of the voltage measurement lead in the third embodiment of the present invention as seen from the direction of the arrow X shown in FIG.

  As shown in FIGS. 12 to 15, the bipolar battery according to the third embodiment is different from the first embodiment described above except that the voltage measurement lead 37 made of FFC is connected to each current collector 13. This is basically the same as the bipolar battery of the embodiment and the second embodiment. Therefore, hereinafter, a detailed description will be given of a configuration in which the voltage measurement lead 37 is connected to the current collector 13 in the third embodiment.

  As shown in FIGS. 12-15, in 3rd Embodiment, the voltage measurement leads 37a-37h connected to each collector 13 of the battery element 21 which has the eight collectors 13 are the said batteries. It is connected to the side surface of the element 21 so as not to overlap each other in a stacked state, shifted in the longitudinal direction of the surface. Therefore, also in the third embodiment, when the voltage measurement leads 37 are connected in such a form, the risk that the voltage measurement leads 37 contact each other and short-circuit can be reduced.

  In the third embodiment, the voltage measurement leads 37a and 37b connected to the two current collectors 13 from the top, and the voltage measurement lead 37g connected to the two current collectors 13 from the bottom. And 37h pass through the lower part of the battery element 21 and are led out of the battery exterior body 33. On the other hand, the voltage measurement leads 37 c to 37 f connected to the current collector 13 located in the center pass through the upper part of the battery element 21 and are led out of the battery outer body 33.

  By connecting the voltage measurement lead 37 in such a form, the bipolar battery of the third embodiment is such that the voltage measurement lead 37 passes above and below the battery element 21 at the top and bottom. It will be supported by. In other words, the part where the voltage measurement lead 37 passes through the upper part and the lower part of the battery element 21 is used as a support for supporting the battery element 21.

  As described above, since the transmission of vibration to the battery element 21 is suppressed by the FFC resin portion used for the voltage measurement lead 37, according to the third embodiment, the bipolar battery having extremely excellent vibration resistance. Can be provided.

  Then, the member which comprises the bipolar battery 11 is demonstrated in order.

  The unit cell 23 is a part where the battery reaction proceeds in the bipolar battery 11, and has a configuration in which the electrolyte layer 19 is sandwiched between the positive electrode layer 15 and the negative electrode layer 17. That is, the layers are laminated in the order of the positive electrode layer 15 / the electrolyte layer 19 / the negative electrode layer 17. In the present invention, “clamping” means a state in which a certain member is interposed between two other members. The contact area between the members is not particularly limited.

The positive electrode layer 15 includes a positive electrode active material. As the positive electrode active material, a lithium-transition metal composite oxide is preferable, and examples thereof include a Li—Mn composite oxide such as LiMn ₂ O ₄ and a Li—Ni composite oxide such as LiNiO ₂ . In some cases, two or more positive electrode active materials may be used in combination.

  The negative electrode layer 17 includes a negative electrode active material. As the negative electrode active material, the above lithium transition metal-composite oxide or carbon is preferable. Examples of carbon include graphite-based carbon materials such as natural graphite and artificial graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, and hard carbon.

  The positive electrode layer 15 and the negative electrode layer 17 may contain other substances if necessary. For example, a binder, a conductive additive, a lithium salt (supporting electrolyte), an ion conductive polymer, and the like can be included. When an ion conductive polymer is included, a polymerization initiator for polymerizing the polymer may be included.

  Examples of the binder include polyvinylidene fluoride (PVdF) and a synthetic rubber binder.

  The conductive assistant refers to an additive that is blended in order to improve the conductivity of the positive electrode layer 15 or the negative electrode layer 17. Examples of the conductive aid include carbon powder such as graphite.

As a lithium salt (supporting electrolyte), LiBETI (lithium bis (perfluoroethylenesulfonylimide); Li (C ₂ F ₅ SO ₂ ) ₂ N), LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ Etc.

  Examples of the ion conductive polymer include polyethylene oxide (PEO) -based and polypropylene oxide (PPO) -based polymers. Here, the ion conductive polymer may be the same as or different from the ion conductive polymer used as the electrolyte in the electrolyte layer 19 of the bipolar battery 11 of the present invention, but is preferably the same. .

  The polymerization initiator is added to act on the crosslinkable group of the ion conductive polymer to advance the crosslinking reaction. Depending on the external factor for acting as an initiator, it is classified into a photopolymerization initiator, a thermal polymerization initiator and the like. Examples of the polymerization initiator include azobisisobutyronitrile (AIBN) and benzyldimethyl ketal (BDK).

  The compounding ratio of the components contained in the positive electrode layer 15 and the negative electrode layer 17 is not particularly limited. The blending ratio can be adjusted by appropriately referring to known knowledge about lithium ion secondary batteries.

  In general, the electrolyte constituting the electrolyte layer 19 includes a liquid electrolyte or a polymer electrolyte. In the present invention, a polymer electrolyte is preferably used. By using the polymer electrolyte, leakage of electrolyte and the like can be prevented, and the safety of the bipolar battery 11 can be improved.

  The polymer electrolyte is composed of an ion conductive polymer, and the material is not limited as long as it exhibits ion conductivity. Made by forming a cross-linked structure by polymerizing a polymerizable polymer for forming a polymer electrolyte by thermal polymerization, ultraviolet polymerization, radiation polymerization, or electron beam polymerization because it can exhibit excellent mechanical strength. Are preferably used. In the electrolyte layer formed of such a polymer electrolyte, no liquid leakage occurs, so that the battery reliability is improved, and the bipolar battery 11 having a simple configuration and excellent output characteristics is formed.

  Examples of the polymer electrolyte include all solid polymer electrolytes and polymer gel electrolytes.

The all solid polymer electrolyte is not particularly limited, and examples thereof include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. Lithium salts such as LiBETI, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) ₂ can be well dissolved in such polyalkylene oxide polymers. In addition, these polymers can exhibit excellent mechanical strength by forming a crosslinked structure. In the present invention, in order to further improve the electrode characteristics, it is preferable that the all solid polymer electrolyte is contained in both the positive electrode layer and the negative electrode layer.

  The polymer gel electrolyte generally refers to an electrolyte solution held in an all-solid polymer electrolyte having ion conductivity. In the present application, a polymer electrolyte having a similar electrolyte solution held in a polymer skeleton having no lithium ion conductivity is also included in the polymer gel electrolyte. The type of electrolyte solution (electrolyte salt and plasticizer) used is not particularly limited.

  When the electrolyte layer is made of a polymer gel electrolyte, the electrolyte layer is formed by impregnating a separator such as a nonwoven fabric with a polymer gel raw material solution and then polymerizing using the above-described various methods. It may be. By using the separator, the filling amount of the electrolytic solution can be increased, and the thermal conductivity inside the battery is ensured.

  The current collector 13 is a metal member that sandwiches each of the unit cells 23 described above in the battery element 21 of the bipolar battery 11. That is, in the battery element 21, the current collector 13 / the positive electrode layer 15 / the electrolyte layer 19 / the negative electrode layer 17 / the current collector 13 are laminated in this order. In other words, in the battery element 21, a plurality of bipolar electrodes in which the positive electrode layer 15 is formed on one surface of the current collector 13 and the negative electrode layer 17 is formed on the other surface are stacked via the electrolyte layer 19. .

  The current collector 13 is made of a conductive material such as an aluminum foil, a copper foil, or a stainless steel (SUS) foil. The general thickness of the current collector 13 is 1 to 30 μm. However, the current collector 13 having a thickness outside this range may be used. The size of the current collector 13 is determined according to the use application of the bipolar battery 11. If a large electrode used for a large battery is to be produced, the current collector 13 having a large area is used. If a small electrode is manufactured, the current collector 13 having a small area is used.

  The voltage measurement lead 37 is made of a flexible flat cable (FFC) as shown in FIGS.

  The material constituting the conductor 2 of the FFC 1 is not particularly limited. As a material constituting the conductor, for example, conductive materials such as copper, aluminum, and nickel are used. Of these, copper is preferably used. These may be used alone or in combination of two or more. Newly developed materials may be used.

  The thickness of the conductor 2 is usually 1 to 20 μm, preferably 1 to 10 μm. However, it is not limited to this value.

  The material constituting the insulating film 3 of the FFC 1 is not particularly limited. Here, in the present invention, the voltage measurement lead made of FFC1 is led out of the battery outer package made of a laminate film or the like. Therefore, the material constituting the insulating film 3 of the FFC 1 is preferably a material that can be fused at the same time by heat fusion at the time of sealing the laminate film. From this viewpoint, for example, resins such as polyethylene, polycello, polypropylene, coated polyester, nylon, coated polypropylene, polystyrene, polyvinyl alcohol, polycarbonate, polyvinylidene chloride, and polyimide can be used. Among these, polyethylene, polypropylene, polyimide, and polyester can be preferably used as a material constituting the insulating film 3. These may be used alone or in combination of two or more. Newly developed materials may be used.

  The thickness of the insulating film 3 is usually 5 to 50 μm, preferably 5 to 10 μm. However, it is not limited to this value.

  The thickness of the entire FFC 1 is not particularly limited. Usually, it is 20-200 micrometers, Preferably it is 20-50 micrometers, More preferably, it is 20-30 micrometers. If FFC1 is too thin, it is difficult to obtain or manufacture. On the other hand, if the FFC 1 is too thick, the merit due to the use of the FFC 1 as the voltage measurement lead is reduced. In addition, as for FFC1, what was manufactured by itself may be used and a commercially available thing may be used. The manufacturing method in particular when manufacturing FFC1 itself is not restrict | limited, A conventionally well-known method may be used suitably. Further, it is sufficient that at least one voltage measuring lead 37 is connected to each current collector 13, and two or more voltage measuring leads 37 may be connected to one current collector 13.

  In the bipolar battery of the present invention, an insulating layer is usually provided around each single battery (cell). This insulating layer is provided for the purpose of preventing current collectors adjacent in the battery from contacting each other and short-circuiting due to slight unevenness of the ends of the unit cells in the battery element. By installing such an insulating layer, long-term reliability and safety can be ensured, and a high-quality bipolar battery can be provided.

  As the insulating layer, any insulating layer may be used as long as it has an insulating property, a sealing property against falling off of the solid electrolyte, a sealing property against moisture permeation from the outside (sealing property), a heat resistance at a battery operating temperature, and the like. Urethane resin, epoxy resin, rubber, polyethylene, polypropylene, polyimide and the like can be used. Of these, urethane resins and epoxy resins are preferred from the viewpoints of corrosion resistance, chemical resistance, ease of production (film forming properties), economy, and the like.

  In the bipolar battery, the positive electrode tab 29 is joined to the positive electrode outermost layer current collector and the negative electrode tab 31 is joined to the negative electrode outermost layer current collector for the purpose of taking out current.

  The material of the tab is not particularly limited, and a known material conventionally used for bipolar batteries can be used. Examples thereof include aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof. Note that the same material may be used for the positive electrode tab and the negative electrode tab, or different materials may be used.

  In the bipolar battery of the present invention, the battery element 21 is preferably housed in a battery outer body 33 such as a battery case in order to prevent external impact and environmental degradation during use. The battery exterior body 33 is not particularly limited, and a conventionally known exterior body can be used. A polymer-metal composite laminate film or the like excellent in thermal conductivity can be preferably used in that heat can be efficiently transferred from a heat source of an automobile and the inside of the battery can be rapidly heated to the battery operating temperature.

  In order to accommodate the battery element 21 in the battery exterior body 33, it is preferable to accommodate the battery element 21 in a sealed state by joining a part or all of the peripheral portion of the exterior body by heat fusion. . At this time, the positive electrode tab 29, the negative electrode tab 31, and each voltage measurement lead 37 are led out of the exterior body by being sandwiched between the portions bonded by the thermal fusion.

  Furthermore, in the bipolar battery of the present invention, as shown in FIG. 16, a socket 40 for connecting a cell controller may be connected to the voltage measurement lead 37. The cell controller is for controlling the voltage of a cell of a bipolar battery, and the socket is for voltage measurement for connecting a voltage measurement lead connected to a current collector to the cell controller. It has an electrode for lead connection. In other words, in the bipolar battery of the present invention, even if the voltage measurement lead is connected to the socket 40 having a voltage measurement lead connection electrode for connecting a single battery controller for controlling the voltage of the single battery. Good. In addition, as the unit cell controller, for example, when the voltage of each unit cell exceeds a specified value, the positive electrode and the negative electrode of the unit cell are electrically connected, and the unit is connected between the positive electrode and the negative electrode. A current bypass circuit that can bypass the intervening electrolyte layer is illustrated.

  A plurality of bipolar batteries of the present invention can be connected to form an assembled battery. That is, the second of the present invention is an assembled battery including the bipolar battery of the present invention. In the assembled battery, a plurality of the bipolar batteries of the present invention or a combination with other batteries are connected in parallel connection, series connection, parallel-series connection or series-parallel connection. Thereby, it becomes possible to respond to the demands for capacity and voltage for various vehicles by variously combining basic bipolar batteries. As a result, it becomes easy to design the required energy and output. Therefore, it is not necessary to design and produce different bipolar batteries for various vehicles, and the basic bipolar battery can be mass-produced, and the cost can be reduced by mass production.

  Here, a preferred embodiment of the assembled battery of the present invention will be described in detail with reference to the drawings.

  FIG. 17 is a side view showing the bipolar battery according to the third embodiment of the present invention as seen from the direction of the arrow X shown in FIG. 18 is a schematic cross-sectional view showing a stacked state of a battery pack in which the bipolar battery according to the third embodiment of the present invention shown in FIG. 17 is stacked.

  As shown in FIG. 18, in the assembled battery of this embodiment, three bipolar batteries of the third embodiment of the present invention are stacked. At this time, in the bipolar battery according to the third embodiment, the portion of the voltage measurement lead that passes through the upper part and the lower part of the battery element is used as a support for supporting the battery element. That is, in the assembled battery of the present embodiment, each bipolar battery to be stacked is stacked via a portion where the voltage measurement leads pass through the upper part and the lower part of the battery element. For this reason, as described above, the resin portion of the voltage measurement lead made of FFC absorbs vibration, and transmission of vibration to the battery element can be suppressed. As a result, an assembled battery having extremely excellent vibration resistance can be provided. FIG. 18 shows the stacked state of the assembled battery formed by stacking the bipolar batteries of the third embodiment of the present invention, but the form of the assembled battery of the present invention is not limited to this. For example, a bipolar battery (for example, a voltage measuring lead passes through only one of the upper part and the lower part of the battery element, and the passing part is used as a support for supporting the battery element (for example, , Those shown in the second embodiment) may be stacked.

  The assembled battery of the present invention is the same as the bipolar battery of the present invention, wherein the bipolar battery and the positive and negative electrode material are the same, and the voltage is the same by connecting in series the number of constituent units of the bipolar battery. A lithium ion secondary battery (preferably a non-bipolar lithium ion secondary battery (also referred to as “general lithium ion secondary battery” in the present specification)) connected in parallel may be used. In other words, the battery forming the assembled battery of the present invention may be a mixture of the bipolar battery of the present invention and a general lithium ion secondary battery. As a result, an assembled battery that compensates for each other's weaknesses is formed by a combination of a bipolar battery that focuses on output and a general lithium ion secondary battery that focuses on energy, thereby reducing the weight and size of the assembled battery. The proportion of each bipolar battery and general lithium ion secondary battery to be mixed can be appropriately determined according to the safety performance and output performance required for the assembled battery.

  Furthermore, a composite assembled battery may be formed by connecting at least two or more of the above assembled batteries in series, parallel, or in series and parallel. Thereby, it becomes possible to respond to the demand for the battery capacity and output for each purpose of use relatively inexpensively without producing a new assembled battery. Moreover, even if a part of the batteries and the assembled battery fail, the composite assembled battery in which a plurality of assembled batteries are connected in series and parallel can be repaired only by replacing the failed part.

  The specific configuration of the assembled battery and the composite assembled battery according to the present invention is not limited in any particular way, and the assembled battery and composite assembled battery using a conventionally known general lithium ion secondary battery are not limited. Forms similar to the configuration and manufacturing method can be applied as appropriate. For example, the configurations and manufacturing methods of conventionally known assembled batteries and composite assembled batteries as described in JP-A-2003-303583 can be used.

  The bipolar battery, the assembled battery, and the composite assembled battery are mounted on, for example, an electric vehicle (EV), a series or parallel hybrid electric vehicle (HEV), a fuel cell vehicle, a hybrid fuel cell vehicle, and the like, and have a high energy density and a high output. It can be suitably used as a vehicle driving power source or an auxiliary power source for which density is required. When at least one of the bipolar battery, the assembled battery, and the composite assembled battery is mounted on a vehicle, it is not particularly limited, but in the center of the vehicle under the seat, under the floor of the vehicle, trunk room, engine room, roof, inside the hood. Etc. can be installed.

  Hereinafter, a preferred embodiment of a method for manufacturing a bipolar battery according to the present invention will be described by taking as an example a method for manufacturing a bipolar battery using a polymer gel electrolyte in an electrolyte layer. The technical scope of the present invention is not limited to the following forms.

  First, a bipolar electrode is produced by producing a positive electrode layer on one side of the current collector and producing a negative electrode layer on the other side. Next, a plurality of the bipolar electrodes are stacked via an electrolyte layer to form a battery element. At this time, only the positive electrode layer is formed on the outermost current collector on the positive electrode side, and only the negative electrode layer is formed on the outermost current collector on the negative electrode side. Then, a bipolar battery is manufactured by taking out a tab from each outermost layer current collector and storing it in a battery outer package or the like.

  In the step of preparing the positive electrode layer on one side of the current collector, after preparing the positive electrode composition, the positive electrode composition is applied onto the current collector, dried and polymerized to prepare the positive electrode layer.

(1) Preparation of composition for positive electrode The composition for positive electrode is normally obtained as a slurry (slurry for positive electrode), and is applied to one surface of a current collector (including the outermost current collector for positive electrode).

  The positive electrode slurry is a solution containing a positive electrode active material. In addition to the positive electrode active material and the solvent, the positive electrode slurry may contain a conductive additive, a binder, a polymerization initiator, an ion transmission polymer, and a lithium salt, if necessary. The positive electrode slurry can be prepared, for example, by adding a binder and a conductive additive to a solvent containing a positive electrode active material and stirring the mixture with a homomixer or the like.

  With respect to the positive electrode active material, the conductive auxiliary agent, the binder, the ion conductive polymer, and the lithium salt, the same form as that described in the section of the positive electrode layer, which is basically a constituent element of the bipolar battery of the present invention, can be used. Therefore, the description is omitted here.

  Examples of the solvent include slurry viscosity adjusting solvents such as N-methyl-2-pyrrolidone (NMP) and n-pyrrolidone, and may be appropriately selected according to the type of the positive electrode slurry.

  The addition amount of the positive electrode active material, the lithium salt, the conductive additive and the like can be appropriately determined so that the obtained bipolar battery satisfies a predetermined relationship.

(2) Preparation of positive electrode layer The positive electrode slurry prepared above is applied onto a current collector and then dried to remove the solvent contained therein.

  The application of the positive electrode slurry onto the current collector can be performed using a conventionally known method such as a coater or a screen printing method so that the thickness of the positive electrode layer is 5 to 100 μm, for example.

  In order to dry the positive electrode slurry applied on the current collector, a conventionally known apparatus such as a vacuum dryer can be used. The drying conditions at this time can be appropriately determined according to the properties of the applied positive electrode slurry.

  The produced positive electrode layer is preferably pressed by a pressing operation in order to improve surface smoothness and thickness uniformity. The pressing operation may be either a cold press roll method or a hot press roll method.

  Next, a negative electrode layer is produced on the surface opposite to the surface on which the positive electrode layer of the current collector is produced. In this case, for example, after preparing a composition for a negative electrode in the same manner as the positive electrode layer described above, the composition may be applied on a current collector and dried.

(3) Preparation of negative electrode composition The negative electrode composition is usually obtained as a slurry (negative electrode slurry), and is the surface opposite to the surface on which the positive electrode layer of the current collector (including the negative electrode current collector) was prepared. To be applied.

  The negative electrode slurry is a solution containing a negative electrode active material. In addition to the negative electrode active material and the solvent, the negative electrode slurry may contain a conductive assistant, a binder, a polymerization initiator, an ion conductive polymer, a lithium salt, and the like, if necessary. About the raw material used and addition amount, since the form similar to what was demonstrated in "(1) Preparation of the composition for positive electrodes" is used, description is abbreviate | omitted here.

(4) Preparation of negative electrode layer After apply | coating the slurry for negative electrodes prepared above to a collector, it is made to dry and the solvent contained is removed. The application method, the drying conditions, and the like are the same as those described in “(2) Production of positive electrode layer”, and thus the description thereof is omitted here.

  The press operation described in “(2) Preparation of positive electrode layer” includes, for example, forming the positive electrode layer on one side of the current collector and forming the negative electrode layer on the other side, and then combining the positive electrode layer and the negative electrode layer. You may go. Further, the press operation may be performed after forming the positive electrode layer on one surface of the current collector, or the press operation may be performed after forming the negative electrode layer on one surface of the current collector. As described above, the form of the press operation target, time, and the like can be appropriately selected as necessary. Moreover, about press conditions, it can select suitably.

(5) Connection of lead for voltage measurement The bipolar electrode produced above is cut out to a desired size. Next, a voltage measurement lead made of FFC is connected to a desired position of the current collector of each bipolar electrode. At this time, if necessary for manufacturing, in order to connect the voltage measurement lead, the positive electrode layer and / or the negative electrode layer are peeled off at a part or all of the peripheral portion of the current collector, A part may be exposed. The specific form when connecting the voltage measurement leads is not particularly limited. For example, when connecting a voltage measurement lead to a current collector, there are two possible cases: connection to the upper surface of the current collector and connection to the lower surface, but it is possible to connect to either surface. If necessary, it may be connected to both sides. In addition, although it is simple and preferable that this process is performed after manufacture of a bipolar electrode, if possible, it may be performed after producing a battery element by the method shown below.

(6) Lamination of a plurality of bipolar electrodes via an electrolyte layer A laminated body is produced by laminating a plurality of bipolar electrodes via a separator. Thereafter, this is impregnated with a gel raw material solution and polymerized to produce a battery element.

  Examples of the separator include those commonly used such as a microporous polyethylene film having a thickness of about 5 to 200 μm, a microporous polypropylene film, and a microporous ethylene-propylene-copolymer film. The number of stacked bipolar electrodes can be appropriately determined by taking into consideration the battery characteristics required for the bipolar battery.

  In the laminate, an electrode on which only the positive electrode layer is formed is connected on the positive electrode outermost layer current collector. In addition, an electrode on which only the negative electrode layer is formed is connected on the outermost current collector for negative electrode.

  The gel raw material solution impregnated in the laminate is a solution prepared by dissolving an ion conductive polymer, a lithium salt, a polymerization initiator, and the like constituting the polymer gel electrolyte in a solvent. Since forms similar to those described above are used as the form of the ion conductive polymer, lithium salt, etc., the description thereof is omitted here.

  The polymerization initiator can be appropriately selected depending on the polymerization method (thermal polymerization method, ultraviolet polymerization method, radiation polymerization method, electron beam polymerization method, etc.) and the compound to be polymerized. Although not particularly limited, for example, benzyl dimethyl ketal as an ultraviolet polymerization initiator, and azobisisobutyronitrile as a thermal polymerization initiator can be mentioned. The solvent is not particularly limited, and examples thereof include slurry viscosity adjusting solvents such as N-methyl-2-pyrrolidone (NMP) and n-pyrrolidone. The addition amount of the polymerization initiator can be appropriately determined according to the number of crosslinkable functional groups contained in the host polymer. Usually, it is about 0.01-1 mass% with respect to the said ion conductive polymer.

  The impregnation of the gel raw material solution is, for example, by laminating a plurality of bipolar electrodes through a separator and preparing a laminated body, and then immersing the produced laminated body in the gel solution or by injecting the gel raw material solution. Can be done. Since the gel raw material solution is not yet gelled, it can penetrate into the electrode and the separator. Further, when impregnating, a very small amount can be supplied by using an applicator or a coater.

  Thereafter, the ion conductive polymer contained in the laminate impregnated with the gel raw material solution is polymerized (crosslinked) by heat, ultraviolet rays, radiation, electron beams or the like. Among these, thermal polymerization can be preferably performed in that the polymerization can be performed easily and reliably. For drying and thermal polymerization, a conventionally known apparatus such as a vacuum dryer can be used. The conditions for drying and thermal polymerization can be appropriately determined according to the properties of the gel raw material solution.

  In addition, it is preferable to manufacture a laminated body from inert viewpoints, such as argon and nitrogen, from a viewpoint which prevents a water | moisture content etc. mixing in the inside of a battery.

  In the present invention, the electrolyte layer is preferably prepared by impregnating a gel solution into a separator and polymerizing (crosslinking) the separator. This is because the use of a separator can increase the filling amount of the electrolytic solution and ensure thermal conductivity. However, the electrolyte layer of the present invention is not limited to such a configuration.

(7) Formation of Insulating Layer For example, the insulating layer is formed by immersing the peripheral portion of the unit cell (cell) of the laminated body in epoxy resin or the like with a predetermined width, or injecting epoxy resin with a predetermined width into the peripheral portion Alternatively, it may be formed by impregnating and then curing the epoxy resin present in the peripheral portion. At this time, preferably, the current collector is masked in advance with a releasable masking material or the like, and the masking agent can be easily removed by removing the epoxy resin after curing.

(8) Joining tabs The positive electrode tab and the negative electrode tab are joined to the positive electrode and negative electrode outermost layer current collectors of the laminate, respectively.

  A method for joining the tab to the outermost layer current collector is not particularly limited, and a conventionally known method such as welding connection may be used. For example, ultrasonic welding or spot welding can be used as the welding connection. Of these, ultrasonic welding is preferably used.

  When a tab is joined to the outermost layer current collector, when a third layer is formed between the tab and the outermost layer current collector, the raw materials used to form the third layer are particularly Although not restricted, For example, the noble metal paste etc. which are used at the time of preparation of a clad material are illustrated.

(9) Packing (Battery completion)
The voltage measurement leads are arranged in a desired form as shown in FIGS. 1 to 4 (first embodiment), FIGS. 7 to 11 (second embodiment), or FIGS. 12 to 15 (third embodiment). To do. Thereafter, the entire battery element is covered with a battery outer package such as a laminate film and sealed by heat fusion or the like to complete a bipolar battery. Thereby, the tolerance with respect to the impact from the outside improves, and environmental degradation is prevented. At the time of sealing, the positive electrode tab, the negative electrode tab, and a part of the voltage measurement lead are led out of the battery.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are for illustrating the best mode of the present invention, and the technical scope of the present invention is not limited only to the following modes.

<Example of battery creation>
Example 1
The bipolar battery of the present invention was produced by the following method.

<Production of FFC>
An aluminum foil (thickness: 40 μm, width: 2 mm) as a conducting wire and a modified polypropylene (thickness: 50 μm, width 45 mm, melting point: 100 ° C.) as an insulating film were prepared.

  The conductive wire was sandwiched between two pieces of the resin and hot pressed at 120 ° C. to produce an FFC having a thickness of 140 μm. At this time, the 8-pole conducting wire was sandwiched at a pitch of 5 mm. Next, by peeling off the resin at both ends, both ends of the conductive wire were exposed by 3 mm to produce an FFC.

<Preparation of bipolar electrode>
First, a collector (SUS) current collector (thickness: 20 μm) was prepared.

Next, LiMn ₂ O ₄ (average particle diameter: 20 μm) as the positive electrode active material, acetylene black as the conductive auxiliary agent, polyvinylidene fluoride (PVdF) as the binder, N-methyl-2-pyrrolidone (Slurry viscosity adjusting solvent) NMP) and well stirred and mixed with a homogenizer to prepare a positive electrode slurry. The positive electrode slurry was defoamed with a defoamer and applied onto the current collector using a coater to form a positive electrode layer. The mass ratio of the positive electrode active material, the conductive additive and the binder added (positive electrode active material: conductive auxiliary agent: binder) is 85: 5: 10, and the slurry viscosity adjusting solvent is the positive electrode active material, conductive auxiliary agent. And an equal mass relative to the binder mixture.

  Next, using hard carbon (average particle size: 20 μm) as the negative electrode active material and PVdF as the binder, the surface and the surface of the current collector on which the positive electrode layer is formed are opposite by the same method and apparatus as the positive electrode layer. On the surface, a negative electrode layer was formed to produce a bipolar electrode. The mass ratio of the addition amount of the negative electrode active material and the binder (negative electrode active material: binder) was 90:10.

  The positive electrode layer and the negative electrode layer were lightly pressed by a roll press to have thicknesses of 45 μm and 46 μm, respectively. Further, after cutting the bipolar electrode into a 120 mm × 70 mm rectangle, the outer peripheral portion of both the positive electrode layer and the negative electrode layer was peeled off with a width of 10 mm to expose the surface of stainless steel (SUS) as a current collector.

  The FFC produced above was cut for each conducting wire to obtain 8 FFCs each having one conducting wire (one pole). The eight FFCs were connected to the current collector surface of the bipolar electrode exposed as described above by ultrasonic welding as voltage measurement leads, and eight bipolar electrodes connected to the FFC were produced. At this time, the FFC was connected so that the completed bipolar battery would have the form shown in FIGS.

<Preparation of gel polymer electrolyte layer>
Prepare an equal volume mixture of propylene carbonate (PC) and ethylene carbonate (EC), and add LiBETI (LiN (SO ₂ C ₂ F ₅ ) ₂ ) as a lithium salt to a concentration of 1.0M. Thus, an electrolytic solution was obtained. These include a copolymer of polyethylene oxide (PEO) and polypropylene oxide (PPO) which are ion conductive polymers as a polymer precursor (average molecular weight: 7500 to 9000), and benzyldimethyl ketal (BDK) as a polymerization initiator. Was further added to prepare a pregel solution. The mass ratio (PC + EC: PEO + PPO) of the equal volume mixture of PC and EC and the copolymer of PEO and PPO in the pregel solution was 90:10.

  The pregel solution is immersed in a nonwoven fabric (thickness: 50 μm, size: 115 mm × 65 mm) made of polypropylene (hereinafter abbreviated as “PP”) as a separator, sandwiched between quartz glass plates, and irradiated with ultraviolet rays for 15 minutes. Thus, the polymer precursor was cross-linked to prepare a gel polymer electrolyte layer.

<Manufacture of bipolar batteries>
The gel polymer electrolyte layer is placed on the positive electrode of the bipolar electrode produced as described above. On the exposed current collector, a sheet-like heat-fusible hot melt (width: 20 mm, (Thickness: 40 μm) was placed so as to surround the electrode layer and the electrolyte layer.

  A new bipolar electrode was further placed on the electrolyte layer, and the above operation was repeated so that the unit cell (positive electrode layer + electrolyte layer + negative electrode layer) became seven layers, thereby forming a battery element. The electrodes were not formed on the outer surfaces of the outermost bipolar electrodes, and the current collector surface was exposed.

  Thereafter, the battery element was hot-pressed to fuse the heat-fusible hot melt as the insulating layer and the current collector.

  Further, the laminated body after hot pressing was put in a laminate pack, and the positive electrode tab and the negative electrode tab and each FFC were led out to be vacuum-sealed by heat fusion, thereby completing a bipolar battery. At this time, it was confirmed that the resin around each FFC was bonded to the laminate pack by heat fusion and sealed.

Example 2
The FFC produced above is cut into four conductive wires to form two FFCs each having four conductive wires (four poles), and these two FFCs are used as voltage measurement leads. A bipolar battery was manufactured using the same method and apparatus as in Example 1 except that it was connected to the current collector surface of the exposed bipolar electrode so as to have the form shown in FIGS.

Example 3
The FFC produced above is cut for every two conductors to form four FFCs each having two conductors (two poles), and these four FFCs are used as voltage measurement leads. A bipolar battery was manufactured using the same method and apparatus as in Example 1 except that it was connected to the current collector surface of the bipolar electrode exposed as described above so as to have the form shown in FIGS.

Comparative Example 1
A bipolar battery was manufactured using the same method and apparatus as in Example 1 except that the FFC as the voltage measurement lead was not connected to the current collector surface.

<Battery evaluation>
<Bipolar battery charging test>
About the bipolar battery manufactured above, the charge test was done on condition of the following.

  The battery was charged to 29.4 V with a current of 0.1 C (CC). Thereafter, the battery was charged at 29.4V (CV). The charging time was 10 hours in total.

  Here, 1C refers to a current value at which the battery is fully charged (100% charged) when charged at that current value for 1 hour. For example, 2C is a current value that is twice that of 1C, and the current value at which the battery is fully charged in 30 minutes.

  About each battery fully charged by said charge, degassing was performed by opening the seal of a laminate film, and the laminate film was sealed again. Then, the voltage of each unit cell and the whole bipolar battery was measured using a voltmeter. The results are shown in Table 1.

  As can be seen from Table 1, in addition to the voltage of the entire bipolar battery, each of the bipolar batteries of Examples 1 to 3 has an FFC connected to each current collector, even after the battery element is formed. It is possible to measure the voltage of a single cell. On the other hand, since the bipolar battery of Comparative Example 1 does not have such means, the voltage of the entire bipolar battery can be measured, but the voltage of each layer of the unit cell cannot be measured.

<Voltage adjustment test for each cell>
As can be seen from Table 1, in the bipolar batteries of Examples 1 to 3, a maximum voltage difference of 11 to 16 mV is generated between the single cells. Therefore, a voltage adjustment test was performed to eliminate this variation and make the voltage of each unit cell constant.

  In this test, a galvanostat was used in a pseudo manner instead of the single cell controller as a device for keeping the voltage constant. In addition, an FFC as a voltage measurement lead connected to an adjacent current collector was connected to the galvanostat, and the set voltage was set to 4.2V.

  As a result, the voltage of each cell could be kept constant at 4.2V. As described above, according to the bipolar battery of the present invention, even when the voltage of each unit cell varies after the battery element is formed, the variation is eliminated by connecting to the external unit cell controller. be able to.

<Vibration resistance test>
The bipolar battery manufactured above was subjected to a vibration resistance test by the following method.

  First, the battery was charged to a voltage of 29.4 V with a constant current of 1 C, and then discharged to a voltage of 17.5 V with a constant current of 1 C. The discharge capacity at this time was measured and used as the initial discharge capacity. After that, the laminate film was once opened and the gas generated during the first charge was released to the outside.

  Next, the bipolar battery was sandwiched and fixed by a flat aluminum plate. Next, a monotonous vibration (amplitude: 3 mm, frequency: 50 Hz) in the vertical direction was applied to the sandwiched battery for 200 hours.

  Thereafter, the discharge capacity was measured by the same method as described above to obtain the discharge capacity after vibration. The percentage of the discharge capacity after vibration to the initial discharge capacity was calculated and used as the capacity maintenance rate. The results are shown in Table 2.

<Contribution to vibration resistance of FFC>
From the results of Examples 2 and 3, in the bipolar battery of the present invention, when connecting the FFC as the voltage measurement lead to the current collector, the FFC was passed through the upper part and / or the lower part of the battery element, It can be seen that the vibration resistance of the bipolar battery can be improved when it is led out of the battery outer casing.

  Moreover, it can be seen from the results of Example 3 that the vibration resistance can be further improved if the FFC is located at the transmission site when the vibration is transmitted to the bipolar battery of the present invention. Thus, by stacking the bipolar battery of the present invention through the portion where the voltage measurement lead passes through the upper part and / or the lower part of the battery element, an assembled battery having excellent vibration resistance can be provided. It is suggested.

It is a top view which shows one preferable form of FFC. It is a model perspective view which shows one preferable form of FFC. It is a model perspective view which shows the external appearance of the bipolar battery of 1st Embodiment. It is a schematic cross section along the AA line shown in FIG. It is a model perspective view which shows the battery element in 1st Embodiment of this invention. It is a side view which shows the connection position of the lead | read | reed for voltage measurement in 1st Embodiment of this invention seen from the direction of the arrow X shown in FIG. It is a model perspective view which shows the external appearance of the bipolar battery of 2nd Embodiment. It is a schematic cross section along the AA line shown in FIG. It is a model perspective view which shows the battery element in 2nd Embodiment of this invention. It is a side view which shows the connection position of the lead | read | reed for voltage measurement in 2nd Embodiment of this invention seen from the direction of the arrow X shown in FIG. It is a side view which shows the connection position of the lead | read | reed for voltage measurement in 2nd Embodiment of this invention seen from the direction of arrow Y shown in FIG. It is a model perspective view which shows the external appearance of the bipolar battery of 3rd Embodiment. It is a schematic cross section along the AA line shown in FIG. It is a model perspective view which shows the battery element in 3rd Embodiment of this invention. It is a side view which shows the connection position of the lead | read | reed for voltage measurement in 3rd Embodiment of this invention seen from the direction of the arrow X shown in FIG. FIG. 4 is a schematic perspective view showing a bipolar battery of the present invention in which a socket 40 for connecting a cell controller is connected to a voltage measurement lead 37. It is a side view which shows the bipolar battery of 3rd Embodiment of this invention seen from the direction of the arrow X shown in FIG. It is a schematic cross section which shows the lamination | stacking state of the assembled battery formed by laminating | stacking the bipolar battery of 3rd Embodiment of this invention shown in FIG.

Explanation of symbols

1 Flexible flat cable (FFC)
2 Conductor 3 Insulating film 4 Thin part 11 Bipolar battery,
13 Current collector,
15 positive electrode layer,
17 negative electrode layer,
19 electrolyte layer,
21 battery elements,
23 single battery (cell),
25 outermost layer current collector for positive electrode,
27 outermost layer current collector for negative electrode,
29 Positive electrode tab,
31 Negative electrode tab,
33 Battery exterior body,
35 insulation layer,
37, 37a to 37h Voltage measurement leads,
40 sockets.

Claims (11)

In a bipolar battery in which a battery element in which a plurality of single cells are connected in series via a current collector is enclosed in a battery exterior body,
A voltage measuring lead made of a flexible flat cable in which a conductor is covered with an insulating film is connected to a current collector for sandwiching the unit cell, and a voltage measurement lead is connected to the current collector body. A bipolar battery characterized in that it is led out to the outside, and at this time, the insulating film is sandwiched by the battery outer package at the lead-out portion of the voltage measurement lead . The material constituting the insulating film of the flexible flat cable is one or two selected from the group consisting of polyethylene, polycello, polypropylene, coated polyester, nylon, coated polypropylene, polystyrene, polyvinyl alcohol, polycarbonate, polyvinylidene chloride, and polyimide. The bipolar battery according to claim 1 , wherein the bipolar battery is a resin of a seed or more. The voltage measuring lead is connected to the current collector such that the voltage measuring lead is displaced in the longitudinal direction of the side surface of the battery element and does not overlap each other when viewed from the stacking direction of the battery element. The bipolar battery described. The electrolyte layer included in the unit cell is a polymer electrolyte layer composed of a polymer electrolyte, a bipolar battery according to any one of claims 1-3. The positive electrode included in the single cell includes a lithium-transition metal composite oxide as a positive electrode active material, and the negative electrode included in the single cell includes carbon or a lithium-transition metal composite oxide as a negative electrode active material. The bipolar battery according to any one of claims 1 to 4 . The voltage measurement leads, said for connecting the single battery controller for controlling the voltages of the cells, the socket is connected with a lead connecting electrode voltage measurement, any one of claims 1 to 5 The bipolar battery described in 1. It said voltage measuring leads, the passes through the upper and / or bottom of the cell element, wherein is derived to the outside of the battery case body, the bipolar battery according to any one of claims 1-6. The bipolar battery according to claim 7 , wherein a portion where the voltage measurement lead passes through an upper part and a lower part of the battery element is used as a support for supporting the battery element. The assembled battery containing the bipolar battery of any one of Claims 1-8 . 9. The assembled battery, wherein the bipolar battery according to claim 7 or 8 is laminated through a portion where the voltage measurement lead passes through an upper part and / or a lower part of the battery element. A vehicle equipped with the bipolar battery according to any one of claims 1 to 8 , or the assembled battery according to claim 9 or 10 .

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