JP2006156357A - Bipolar battery, battery pack, vehicle mounting these batteries - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bipolar battery having a built-in discharge circuit automatically adjusting capacity balance. <P>SOLUTION: In the bipolar battery formed by alternately laminating a plurality of bipolar electrodes in which a positive electrode layer is formed on one surface of a current collector and a negative electrode layer on the other surface and an electrolyte layer conducting ion exchange between the bipolar electrodes, the discharge circuit electrically connecting the adjacent bipolar electrodes is formed on the same plane in at least one layer out of the positive electrode layer, the negative electrode layer, and the electrolyte layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bipolar battery having a built-in discharge circuit capable of automatically balancing the capacity, an assembled battery, and a vehicle equipped with these batteries.

  As described in Patent Document 1 below, the bipolar battery is a battery constructed by laminating a plurality of bipolar electrodes, and has various excellent characteristics such as thinness, light weight and good heat dissipation. ing.

When a bipolar battery is used as a power source for a vehicle, reliability and stability are required. When the plurality of single cells constituting the bipolar battery (one single cell is formed between the bipolar electrodes) are not the same charge amount, the required output performance and capacity performance cannot be exhibited. Therefore, it is necessary to always keep the capacity of each unit cell uniform. Therefore, a voltage detection line (used to detect the voltage of the single cell) and a bypass line (used to bypass the single cell) are connected to each cell, and the voltage detected from the voltage connection line Accordingly, the connection of the bypass line is controlled so that charging / discharging of each unit cell can be individually controlled.
JP 2000-195495 A

  However, since the voltage detection line and the bypass line must be drawn from each of the current collectors provided between the bipolar electrodes, it takes a lot of manpower to draw out and the sealing of the sealing portion of the exterior material must be ensured. The omission was desired in that it would not be.

  The present invention has been made to solve the above-described problems of the prior art, and a discharge circuit that can automatically balance the capacitance without using a voltage detection line or a bypass line is provided. An object of the present invention is to provide a built-in bipolar battery, an assembled battery, and a vehicle equipped with these batteries.

  In order to achieve the above object, a bipolar battery according to the present invention includes a bipolar electrode in which a positive electrode layer is formed on one surface of a current collector and a negative electrode layer is formed on the other surface, and the bipolar electrode between In the bipolar battery in which a plurality of electrolyte layers that perform ion exchange are alternately stacked in the positive electrode layer or the negative electrode layer, or in the same plane of at least one of the electrolyte layers, adjacent bipolar electrodes A discharge circuit is formed to electrically conduct the current.

  In the bipolar battery according to the present invention, since the discharge circuit is formed in the same plane of the positive electrode layer or the negative electrode layer of the bipolar electrode, or at least one of the electrolyte layers, the voltage detection line and the bypass line are externally connected. Therefore, the optimum capacity balance can be automatically obtained based on the voltage of each unit cell.

  According to the bipolar battery of the present invention configured as described above, adjacent bipolar electrodes are electrically connected to each other in the same plane of at least one of the positive electrode layer or the negative electrode layer of the current collector or the electrolyte layer. Since the discharge circuit that conducts automatically is formed, it is possible to automatically balance the capacity of each unit cell without drawing out the voltage detection line and bypass line outside the bipolar battery, reducing the number of manufacturing steps and the bipolar. The reliability of the battery can be improved.

  Embodiments of a bipolar battery, 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 bipolar battery are exaggerated, but this is done to facilitate understanding of the contents of the invention. Yes, it is not consistent with the thickness and shape of each layer of an actual bipolar battery.

  FIG. 1 is an external view of a bipolar battery according to the present embodiment. The bipolar battery 100 has a rectangular flat shape as shown in the figure, and a positive electrode tab 120 </ b> A and a negative electrode tab 120 </ b> B for extracting electric power are drawn out from both sides thereof. The power generation element 160 is wrapped with an exterior material (for example, a laminate film) 180 of the bipolar battery 100, and the periphery thereof is heat-sealed. The power generation element 160 is sealed with the positive electrode tab 120A and the negative electrode tab 120B pulled out. .

  2 and 3 are schematic configuration diagrams of the inside of the bipolar battery 100, and FIGS. 4 to 9 are diagrams for explaining a discharge circuit built in the bipolar battery 100. Bipolar battery 100 according to the present embodiment selectively discharges materials necessary for forming each layer from a plurality of nozzles in the same manner as when printing an image using an ink jet printer. It was created by forming layers sequentially from the bottom layer as depicted. Moreover, although the bipolar battery 100 has a discharge circuit, this discharge circuit is also drawn by an inkjet system.

  FIG. 2 is an exploded perspective view for explaining the internal structure of the bipolar battery 100. In this figure, each layer is disassembled for convenience of explanation, but in this embodiment, the layers are drawn in order from bottom to top by the ink jet method as described above, and therefore the layers cannot actually be disassembled. .

  In the present embodiment, the power generation element 160 is formed by repeatedly applying a predetermined adhesion pattern for each layer by an ink jet printer method. That is, in this embodiment, as shown in FIG. 2, the adhesion patterns shown in the first layer to the fifth layer are applied to the substrate 200 in order as in the case of forming a color image with an inkjet printer. A battery 150 is formed, and the unit cells 150 are repeatedly stacked seven times to form a power generation element 160 as shown in FIG.

The materials necessary for forming each layer will be described below.
1. Production of positive electrode ink: LiMn ₂ O ₄ (85 wt%) used as the positive electrode active material used for forming the positive electrode active material 212, acetylene black (5 wt%) as a conductive additive, and PVdF (10 wt%) as a binder were prepared. The viscosity of the ink was adjusted using NMP as the slurry viscosity adjusting solvent.

The positive electrode layer is a layer configured by mixing an active material and, if necessary, a conductive additive, a binder, an electrolyte, and the like. The active material is not particularly limited in the present embodiment. Examples of the positive electrode active material include Li—Mn composite oxides such as LiMn ₂ O ₄ , Li—Ni composite oxides such as LiNiO ₂ , Li—Co composite oxides such as LiCoO ₂ , and Li—FePO ₄ . Examples thereof include iron phosphate complex oxides. Of these, Li—Ni-based composite oxides are preferable from the viewpoint of excellent conductivity. In some cases, two or more positive electrode active materials may be used in combination. In addition, although the material of the Li battery is mentioned here, carbon may be used as a capacitor. Alternatively, a water electrolyte battery material such as nickel hydroxide, lead oxide, lead sulfate, or the like may be used.

As the conductive assistant, a carbon material such as carbon black or graphite powder, a material having high conductivity, such as gold or platinum, which is difficult to be electrolyzed is used. Examples of the binder include polyvinylidene fluoride (PVdF), styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyolefins, polyimide, polyamideimide, and polyurethane. The electrolyte is a mixture of an ion conductive polymer and a supporting electrolyte. The ion conductive polymer is not particularly limited. Examples thereof include polyethylene oxide (PEO) -based and polypropylene oxide (PPO) -based polymers. The ion conductive polymer contained in the active material layer may be the same as or different from the ion conductive polymer used as the electrolyte in the electrolyte layer of the battery in which the electrode of the present invention is employed. Preferably they are the same. Examples of the supporting electrolyte include 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 and the} like. .
2. Production of negative electrode ink: used for forming negative electrode active material 202 Hard carbon (90 wt%) was prepared as a negative electrode active material, and PVdF (10 wt%) was prepared as a binder. The viscosity of the ink was adjusted using NMP as the slurry viscosity adjusting solvent.

The negative electrode layer is a layer configured by mixing an active material and, if necessary, a conductive additive, a binder, and an electrolyte. Examples of the negative electrode active material include carbon materials such as a crystalline carbon material and an amorphous carbon material. Specific examples include graphite-based carbon materials such as natural graphite and artificial graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, and hard carbon. Among these, hard carbon is preferable from the viewpoint of battery control. In the case of a capacitor, a carbon material may be used, and in the case of a water electrolyte battery, a hydrogen storage alloy, cadmium hydroxide, lead sulfate, or the like may be used.
3. Preparation of Electrolyte Ink: PC-EC 1M LiBETI (90 wt%) used as an electrolyte for forming the ion conductive material 208 and PVdF-HFP (10 wt%) containing 10% of HFP copolymer as a host polymer were prepared. The viscosity of the ink was adjusted using dimethyl carbonate (DMC) as the slurry viscosity adjusting solvent.

The electrolyte layer may be a liquid, gel, or solid phase. In consideration of safety when the battery is damaged and prevention of liquid junction, the electrolyte layer is preferably a gel polymer electrolyte layer or an all-solid electrolyte layer. By using a gel polymer electrolyte layer as an electrolyte, the fluidity of the electrolyte is lost, the outflow of the electrolyte to the current collector can be suppressed, and the ionic conductivity between the layers can be blocked. Examples of the gel electrolyte host polymer include PEO, PPO, PVdF, polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), PAN, PMA, and PMMA. In order to ensure ionic conductivity, a supporting salt is preferably included. When the battery is a lithium secondary battery, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , or a mixture thereof is used as the supporting salt. it can. However, it is not necessarily limited to these. As described above, polyalkylene oxide polymers such as PEO and PPO often dissolve lithium salts such as LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) _2. Yes. Moreover, excellent mechanical strength is exhibited by forming a crosslinked structure.
4). Preparation of conductive material ink: Used to form conductive materials 200, 204, 204A, 214, and the like.

  Graphite (average particle size 0.8 m; 90 wt%) as carbon particles is prepared as conductive particles, PVdF (10 wt%) is prepared as a binder, NMP is used as a viscosity adjusting solvent, and current collector ink containing conductive particles is prepared. Prepared.

The conductive material only needs to have conductivity and is not limited to this embodiment. Examples include, but are not limited to, aluminum particles, SUS particles, silver particles, gold particles, copper particles, titanium particles, and the like instead of carbon particles. Alloy particles may be used. As a binder, polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), poly Vinyl chloride (PVC), polyvinylidene fluoride (PVdF), or a mixture thereof. Furthermore, the conductive material is not necessarily required to contain conductive particles using a polymer material (conductive polymer) having high electronic conductivity. Examples of the conductive polymer include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, polyoxadiazole, or a mixture thereof.
5. Production of Insulating Material Ink: PVdF-HFP (100 wt%) containing 10% of HFP copolymer as a host polymer used for forming the insulating material 206 was prepared. The viscosity of the ink was adjusted using dimethyl carbonate (DMC) as the slurry viscosity adjusting solvent.

The insulating material is not limited to this embodiment as long as it does not have conductivity. For example, a polymer material used for forming the electrolyte layer can be suitably used. PEO, PPO, PVdF, polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), PAN, PMA, PMMA, and the like.
6). Preparation of discharge circuit ink: used to form discharge circuit 210. This will be described later.
7). Positive electrode tab 120A, negative electrode tab 120B
Use an AL plate. In order to take out an electric current, it is desirable to have a low resistance, and it is preferable to have a thickness of about 100 μm.
8). Manufacturing apparatus Ink application by an inkjet method was performed according to the following procedure. In addition, in order to prevent the problem that the ink solvent dissolves the plastic parts in the ink introduction part of the ink jet printer, replace the parts in the ink introduction part with metal parts and apply the ink directly from the ink reservoir to the metal parts. I was allowed to supply. Further, in order to prevent the active material in the ink from precipitating, the ink reservoir was always stirred using a rotary blade. The inkjet printer was controlled by a commercially available computer and software. The ink application was made by printing a pattern created on a computer using an inkjet printer.

  On the conductive material 200 as the base material shown in FIG. 2, as shown in the drawing, the negative electrode active material 202 is printed at the central portion thereof, and the conductive material 204 is printed at a part thereof, and the insulating material 206 is provided at the outer peripheral portion thereof. Print. An adhesion pattern such as which part of the conductive material 200 is to be printed with the material such as the negative electrode active material 202, the conductive material 204A, and the insulating material 206 is set in advance for each layer. In response to this, a conductive material or an insulating material is selectively sprayed in each region.

  When printing of the first layer is completed, printing of the second layer is started. On top of the first layer, an ion conductive material 208 as an electrolyte layer for exchanging lithium ions is printed in the central portion, and conductive materials 204B and 204C are printed on a portion thereof, and an insulating material 206 is printed on the outer peripheral portion thereof. To do. In the present embodiment, the discharge circuit 210 is formed so as to be sandwiched between the conductive materials 204B and 204C in the same plane of the second layer. The discharge circuit 210 is turned on / off according to the voltage of the unit cell 150. The structure and the like of the discharge circuit 210 will be described later with reference to FIGS.

  When the second layer printing is completed, the third layer printing is started. On the second layer, a positive electrode active material 212 that forms a positive electrode layer of a bipolar electrode is printed at the central portion thereof, and a conductive material 204D is printed on a part thereof, and an insulating material 206 is printed on an outer peripheral portion thereof.

  When printing of the third layer is completed, printing of the fourth layer is started. A conductive material 214 serving as a current collector is printed on the entire surface of the third layer.

  When printing of the fourth layer is completed, printing of the fifth layer is started. The fifth layer is printed on the fourth layer, and the fifth layer is the same as the first layer. That is, on the fourth layer, the negative electrode active material 202 that forms the negative electrode layer of the bipolar electrode is printed at the center, and the conductive material 204A is printed on a part thereof, and the insulating material 206 is printed on the outer periphery thereof.

  Note that the conductive material 200, the fourth conductive material 214, and the layer therebetween are the unit cells 150, and the third to fifth layers are the bipolar electrodes 220.

  The above-described printing is repeated a total of seven times to form a power generation element 160 as shown in FIG. The conductive material 200 which is the lowermost base material of the power generation element 160 is connected to the negative electrode tab 120B, and the conductive material 200 which is the uppermost base material is connected to the positive electrode tab 120A. Since the power generation element 160 has seven unit cells 150 connected in series, a voltage seven times that of the unit cell 150 appears between the positive electrode tab 120A and the negative electrode tab 120B.

  Each cell 150 of the power generation element 160 formed as described above is provided with a discharge circuit 210. The discharge circuit 210 has a function of electrically connecting the bipolar electrodes 220 adjacent in the stacking direction. As described above, by incorporating the discharge circuit 210 in the power generation element 160, a voltage detection line for detecting the voltage of the unit cell 150 and a bypass line for bypassing the unit cell 150 are provided from the inside of the bipolar battery 100 to the outside. There is no need to pull out, and the sealing property of the exterior material 180 is improved, and the reliability is improved. Of course, the number of parts can be reduced by eliminating the need for the voltage detection line and the bypass line, and the number of assembling steps and the manufacturing cost can be reduced. Furthermore, since it is not necessary to insulate each voltage detection line and each bypass line inside and outside the bipolar battery 100, there is no risk of failure such as an internal short circuit, and the reliability is improved in terms of ensuring insulation. Furthermore, since it is not necessary to separately provide a discharge circuit group (capacity balance adjustment circuit) outside the bipolar battery 100, the installation area of the bipolar battery 100 can be reduced.

  In this embodiment, the discharge circuit 210 is provided on the same plane as the layer on which the ion conductive material 208 is printed. However, the discharge circuit 210 is provided on the same plane as the layer on which the negative electrode active material 202 or the positive electrode active material 212 is printed. Also good. Alternatively, it may be formed across a plurality of layers.

  The discharge circuit 210 has a function of forming a threshold value of the discharge voltage. If the voltage of the unit cell 150 reaches a voltage equal to or higher than the threshold value, the discharge circuit 210 positively makes the positive and negative sides of the unit cell 150 conductive. On the other hand, if the voltage of the unit cell 150 does not reach the threshold value, the active discharge is not performed. The voltage of the unit cell 150 is detected through the conductive materials 204A to 204D that are electrically connected to each other. Therefore, as shown in FIG. 4, the discharge circuit 210 is provided with zener diodes 231 and 232 for forming a threshold value of the discharge voltage. Specifically, the discharge voltage threshold is set between 3.6V and 4.1V. When the discharge circuit 210 is in the conductive state, a current that is 100 times or more of that in the conductive state does not flow. The threshold value of the discharge voltage is set in such a range when a single cell having a high charge state is determined by voltage and the operating voltage range is 3.0 to 4.2 V. In that case, it is possible to discharge the cells having a voltage of 4.1 V or more to make the voltages uniform. This is because in the case of a hybrid vehicle that uses only an intermediate state of charge, it is possible to discharge a battery of 3.6 V or more to make the voltage uniform.

  The discharge circuit 210 includes light emitting elements 233 and 234 that emit light with a current that flows when the battery cell 150 is discharged, and an optical sensor 503 that is sensitive to the light emission is provided in the vicinity of the light emitting elements 233 and 234. . Since the light emitting elements 233 and 234 are broken when a flowing current is too large, the discharge circuit 210 is provided with constant current circuits 235 and 236. In this embodiment, an element such as a MOSFET, JFET, or MSSFET is used as an element for forming a constant current circuit.

  The bipolar electrode 220, the ionic conductive material 208, the discharge circuit 210, and the optical sensor are covered and sealed with a laminate film (light reflective) 180 as an exterior material, and as shown in FIG. With the 120B and voltage detection line 140 pulled out, the outer peripheral portion of the laminate film 180 is heat-sealed. When the light emitting elements 233 and 234 provided in the discharge circuit 210 emit light, that is, when the unit cell is equal to or higher than the breakdown voltage of the Zener diode, it is reversely charged and becomes a negative voltage equal to or lower than the forward voltage of the Zener diode. In this case, the light is reflected in the laminate film and detected by the optical sensor, and an abnormality is detected outside, for example, charging / discharging of the battery can be stopped. Therefore, the installation location of the optical sensor 503 may be a location where the light emission of the light emitting elements 233 and 234 can be detected in the laminate film. In addition, it turns out that one of the cell 150 which comprises the electric power generation element 160 with the signal from an optical sensor is an overvoltage state.

  Note that in this embodiment mode, the discharge circuit 210 provided with the light sensor and including the light emitting elements 233 and 234 is described as an example. However, the discharge circuit does not include the light sensor and does not include the light emitting element. Is also possible.

  The discharge circuit 210 as shown in FIG. 4 is formed in the same plane as the ion conductive layer on which the ion conductive material 208 is printed as shown in FIG. Use to form. A specific layer structure of the discharge circuit 210 is shown in FIG. There are various printing techniques, but in this embodiment, the printing technique is formed using an ink jet method.

  The discharge circuit is acene, thiophene, phenylene, vinylene, metal substituted phthalocyanine, PEDOT, TCNQ, PTCDA, NTCDA, PTCDI, NTCDI, C60 and C70, Alq3, Ir (ppy) 3, BCP, TPD, NPD, etc. The organic semiconductor layer is composed of a diode or transistor including an oxide such as ITO, a metal such as aluminum, magnesium, gold, or silver. By forming a discharge circuit using the organic semiconductor layer, a thin and small discharge circuit is formed. Can be realized. The discharge circuit 411 preferably includes a Schottky diode formed by laminating an organic semiconductor and a metal and an organic light emitting diode layer. By forming the discharge circuit 411 using the Schottky diode layer, the discharge circuit 411 is simpler. It becomes a structure and can implement | achieve cost reduction.

  In the Schottky diode, for example, pentacene, which is an acene-based material, is formed as a semiconductor layer on gold, and then silver or aluminum is formed thereon and stacked. Here, the material is not limited to this as long as the junction between the semiconductor layer and aluminum and silver is a Schottky junction.

  Organic light emitting diodes are, for example, hole transport materials such as TPD and NPD on gold, then light emitting materials such as Alq3 and Ir (ppy) 3, then electron conducting materials such as BCP, metals such as aluminum and silver The layers were laminated in this order. Hole injection can be performed between gold and a hole transport material, and electron injection is performed between aluminum and BCP. If electrons and holes are injected into the light emitting material layer, light is generated by the light emitting material, and the combination of materials is not limited to these.

  The transistor was stacked on gold as a source electrode in the order of pentacene, which is an acene-based material as a semiconductor layer, net-like aluminum, metal such as silver as a gate electrode, pentacene, and gold as a drain electrode. The transistor exemplifies the SIT structure in which the resistance between the two gold electrodes is changed by changing the region of the empty layer in pentacene by the voltage applied to the gate electrode of the Schottky junction and the junction of pentacene. The material is not particularly limited as long as it has an SIT structure in which an ohmic junction can be formed by the source and drain electrodes and a Schottky junction can be formed by the gate electrode. Further, a MOSFET structure, a JFET structure, a bipolar transistor structure, or the like may be configured.

  As shown in FIG. 5, a negative electrode material 261, an insulating material 262, a hole conducting material 263, and an electron conducting material 264 are sprayed on a conductive material 260 according to a predetermined pattern, and a hole conducting material 263 and an electron conducting material 264 are injected. Can be ensured, an EL (electroluminescence) material 265 is jetted onto the hole conducting material 263 and the electron conducting material 264. When the thickness of the EL material 265 can be secured, the electrolyte 266, the insulating material 262, the electron conductive material 264, and the hole conductive material 263 are sprayed in accordance with a predetermined pattern. When the thicknesses of the electron conductive material 264 and the hole conductive material 263 are secured, the conductive material 267 is sprayed over the electron conductive material 264 and the hole conductive material 263. When the thickness of the conductive material 267 can be secured, the P-type semiconductor 268 is injected onto the conductive material 267. If the thickness of the electrolyte 266 can be secured before the P-type semiconductor 268 reaches a predetermined thickness, the positive electrode material 269 is sprayed instead of the electrolyte 266. When the P-type semiconductor 268 has a predetermined thickness, an N-type semiconductor 270 and a metal (portion surrounded by a square in the figure) are sprayed on the P-type semiconductor 268 according to a predetermined pattern. Finally, a conductive material 260 is injected to form a discharge circuit.

  In FIG. 5, a light-emitting layer, that is, a light-emitting element (light-emitting diode) 233 or 234, is formed of a stacked body of a hole conductive material 263, an EL material 265, and an electron conductive material 264, and a P-type semiconductor 268 and an N-type semiconductor. 270 and a zener diode layer, that is, a zener diode 231 or 232 is formed. A portion where the P-type semiconductor 268 is formed in the N-type semiconductor 270 is a constant current circuit 235 or 236. Note that a P-type semiconductor layer or a metal layer is formed in a stripe shape on the N-type semiconductor layer of the Zener diode 231 or 232, but the metal layer is connected to the P-type semiconductor layer outside.

The contact area between the discharge circuit 210 and the bipolar electrode 150 is preferably 0.06 mm ² or more with respect to the battery capacity 1 Ah of the bipolar electrode 150. Thus, the contact area is determined with respect to the battery capacity for the following reason. For example, a battery that discharges 50% due to self-discharge within one month is naturally discharged at 0.7 mA per 1 Ah. In this case, it is not possible to stand for one month, so the battery needs to be replaced. In order to restore the voltage balance at a speed three times that of the self-discharge, it is necessary to set the lower limit discharge current of the voltage balance function in the discharge circuit 210 to 2 mA, which is three times the self-discharge current. The allowable heat generation amount of the semiconductor PN junction is about 120 mw per 1 mm ² . When the battery voltage is 3.5 V, a discharge circuit area of about 0.06 square millimeters per 1 Ah of battery is required.

  Thus, the area of the discharge circuit 210 can be reduced by securing a sufficient discharge current under actual use conditions and optimizing the amount of heat generated in the discharge circuit portion.

  An abnormal voltage detection circuit and a voltage balance circuit constituting the discharge circuit 210 and their discharge characteristics are shown in FIGS. The characteristic of the abnormal voltage detection circuit is that if the voltage of the unit cell 150 is equal to or higher than a preset discharge voltage threshold (battery abnormal voltage), the current increases according to the voltage value. . On the other hand, if the voltage is less than the discharge voltage threshold value, the current hardly flows (allowable dark current). When the voltage is equal to or higher than the threshold, a large current flows through the light emitting elements 233 and 234, so that light is emitted. Although the current flowing through the light emitting elements 233 and 234 is regulated by the resistance value of the resistor 240, a constant current circuit 236 is provided so that the current does not exceed the allowable current of the light emitting elements 233 and 234 (see FIG. 4). ). An optical sensor is installed in the vicinity of the light emitting element, and a minimum means for optically isolated communication is configured to transmit to the outside by potential conversion that the optical sensor has deviated from the discharge voltage threshold range.

The characteristic of the voltage balance circuit is that the current flows through the Zener diode 231 so as not to exceed the threshold if the voltage of the unit cell 150 is equal to or higher than a preset discharge voltage threshold (battery abnormal voltage). have. In order to make the breakdown voltage of the PN junction in the Zener diodes 231 and 232 the same as the setting of the threshold value of the discharge voltage, the doping concentration is in the range of 10 ¹⁷ to 10 ¹⁸ and the thickness of the sky layer is 0.1 μm to 1.0 μm. The range is as follows. As shown in FIG. 8, the breakdown voltage of the semiconductor PN junction is determined by the doping concentration and the thickness of the sky layer. Therefore, the required doping concentration and thickness can be determined from the figure. If the characteristics of the Zener diodes 231 and 232 are optimized, the dark current of the discharge circuit 210 can be suppressed, battery overdischarge can be avoided when left for a long period of time, and a highly reliable battery can be supplied.

  In this embodiment, Zener diodes 231 and 232 are formed by stacking a P-type semiconductor 268 on a conductive material 267 and an N-type semiconductor 270 layer thereon to form a PN junction, and a punch-through region having a low doping concentration. Is provided at the PN junction at 0.5 μm or less, so that the breakdown voltage is controlled by the thickness of the punch-through region. As a result, the battery is slowly discharged to the breakdown voltage of the diode, and the breakdown voltages are aligned with high accuracy, so that the voltages of the series batteries are aligned, and the battery's inherent capacity can be used more. The breakdown voltage can be controlled by adjusting the doping concentration of the P-type and N-type layers without creating a region having a low doping concentration.

Although another form of the discharge circuit 210 is shown in FIG. 9, the only difference from FIG. 5 is the layer structure of the part that constitutes the constant current circuit. That is, on the conductive material 267, an N-type semiconductor layer or a layer in which a metal layer is formed in a stripe shape is stacked on a P ^- type semiconductor layer, and a P ⁻ -type semiconductor 271 is further stacked on the layer. The only difference is that an N-type semiconductor is stacked thereon.

  Even if the discharge circuit 210 has such a layer structure, it can have the functions of the abnormal voltage detection circuit and the voltage balance circuit as described above.

  As described above, according to the present embodiment, since the discharge circuit is formed between the single cells, each single cell can be obtained without drawing the voltage detection line and the bypass line outside the bipolar battery. Thus, it is possible to automatically balance the capacity of the battery, thereby reducing the number of manufacturing steps and improving the reliability of the bipolar battery.

  Next, a preferred embodiment in the case of using the light emitting elements 233 and 234 will be described. In particular, in this embodiment, the electrode formation is not particularly performed by the inkjet method, and the positive electrode layer 269 and the negative electrode layer 261 are applied to the outer peripheral portion of the electrode coated with the positive electrode layer 269 on both sides of the current collector foil 260 manufactured by a normal method. The constant current circuits (including the zener diodes 231 and 232) 235 and 236 and the light emitting elements 233 and 234 are formed on both surfaces of the electrode by the inkjet method. The electrical connection between the adjacent constant current circuit and the light emitting element is performed using a conductive adhesive as will be described later.

  As shown in FIG. 10, the light emitting element is preferably formed to be elongated on the side surface of the electrode 260. The light emitting element emits a lot of light in a direction perpendicular to the surface of the battery, but the light outlet is the side edge of the battery. Therefore, light from a position far from the side surface is absorbed in the middle, and it is difficult to extract light when the light emitting element is far from the side surface of the battery. It is desirable that the light-emitting element be made long and narrow on the battery side. In the present embodiment, the length is 10 mm or less, and is preferably 1% or less of the entire battery area.

  Next, details of the periphery of the light emitting elements 233 and 234 will be described with reference to FIG. Here, the conductive adhesive sealant 501 is preferably a polymer material containing conductive particles, and in this embodiment, a material containing metal conductive particles in order to form a reflective layer. The sealant 502 is made of a non-conductive polymer material and is transparent.

  12 is a cross-sectional view of the A surface of FIG.

According to the embodiment of FIGS. 11 and 12, since both the conductive adhesive sealant 501 and the sealant 502 are bonded to the light emitting elements 233 and 234, the light emitting elements 233 and 234 are interposed via the sealant 502. Can be guided to the side of the battery. Furthermore, by spreading the conductive sealant 501 in the vicinity of the electrolyte layer, the conductive sealant 501 serves as a reflector, and light can be more suitably guided to the battery side surface. Further, the resistance value of the conductive adhesive layer connecting the issuing elements 233 and 234 is used as the resistance of the issuing elements 233 and 234. Since the voltage of the battery may rise to about 10 V and the issuing elements 233 and 234 can withstand up to 1 A / cm ² , the resistance value is desirably 10 Ω / cm ² or more.

  A plurality of the bipolar batteries described above are connected in series or in parallel to form an assembled battery module 250 (see FIG. 13), and a plurality of assembled battery modules 250 are connected in series or in parallel to form an assembled battery. 300 can also be formed. FIG. 13 shows a plan view (FIG. A), a front view (FIG. B), and a side view (FIG. C) of the assembled battery 300. The assembled battery module 250 is electrically connected like a bus bar. The assembled battery modules 250 are stacked in a plurality of stages using the connection jig 310. How many bipolar batteries 110 are connected to create the assembled battery module 250 and how many assembled battery modules 250 are stacked to create the assembled battery 300 depend on the vehicle (electric vehicle) to be mounted. It may be determined according to the battery capacity and output.

  Thus, the assembled battery 300 in which a plurality of assembled battery modules 250 are connected in series and parallel can obtain high capacity and high output, and the reliability of each assembled battery module 250 is high. The long-term reliability of 300 can be maintained. Further, even if some of the assembled battery modules 250 fail, repair can be performed by simply replacing the failed part.

  In the case of the assembled battery 300, since a large number of bipolar batteries 100 are connected in series, if the self-discharge due to a minute short circuit of one bipolar battery 100 is accelerated, the balance of the charged state is lost. In the worst case, if a bipolar battery with a 0% charge state and a 100% bipolar battery are connected in series, one bipolar battery is overcharged and discharged when one bipolar battery is overdischarged. As a result, no current can flow. Since the bipolar battery according to the present invention has a discharge circuit therein, the charge / discharge capacity is automatically balanced for each bipolar battery, which improves the reliability and durability of the assembled battery. it can. Further, since an external device for adjusting the capacity is not necessary, the assembled battery can be reduced in size.

  In order to mount the assembled battery 300 on the electric vehicle 400, it 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 running performance. Further, the assembled battery controller 401 determines that the capacity is being adjusted while the light sensor 503 is receiving light, and can extend the life of the assembled battery by limiting the output.

  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.

  According to the present invention, the optimum capacity balance can be automatically secured based on the voltage of each unit cell without drawing out the voltage detection line and the bypass line to the outside, so that mass production and reliability of the bipolar battery can be achieved. Greatly helping to improve.

1 is an external view of a bipolar battery according to an embodiment. It is a schematic block diagram inside a bipolar battery. It is a schematic block diagram inside a bipolar battery. It is a figure where it uses for description of the discharge circuit incorporated in a bipolar battery. It is a figure where it uses for description of the discharge circuit incorporated in a bipolar battery. It is a figure where it uses for description of the discharge circuit incorporated in a bipolar battery. It is a figure where it uses for description of the discharge circuit incorporated in a bipolar battery. It is a figure where it uses for description of the discharge circuit incorporated in a bipolar battery. It is a figure where it uses for description of the discharge circuit incorporated in a bipolar battery. It is a figure where it uses for description of the light emitting element incorporated in a bipolar battery. It is a figure where it uses for description of the light emitting element incorporated in a bipolar battery. It is a figure where it uses for description of the light emitting element incorporated in a bipolar battery. It is a schematic block diagram of an assembled battery. It is a figure which shows the state with which the assembled battery was mounted in the vehicle.

Explanation of symbols

100 bipolar battery,
120A positive electrode tab,
120B negative electrode tab,
150 cells,
160 power generation elements,
180 laminate film,
200 conductive material,
202 negative electrode active material,
204A-204D conductive material,
206 insulation,
208 ionic conductive material,
210 discharge circuit,
212 positive electrode active material,
214 conductive material,
220 bipolar electrodes,
231 and 232 Zener diodes,
233, 234 light emitting element,
235, 236 constant current circuit,
250 battery module,
261 negative electrode material,
262 insulating material,
263 hole conduction material,
H.264 electron conducting material,
265 EL material,
266 electrolyte,
267 conductive material,
268 P-type semiconductor,
269 positive electrode material,
270 N-type semiconductor,
271 P ^- type semiconductor,
300 battery packs,
310 connection jig,
400 electric car,
401 battery controller
501 conductive sealant,
502 sealant,
503 Optical sensor.

Claims (11)

A bipolar electrode in which a positive electrode layer is formed on one surface of the current collector and a negative electrode layer is formed on the other surface, and a plurality of electrolyte layers that perform ion exchange between the bipolar electrodes are alternately stacked. In the bipolar battery
A bipolar battery characterized in that a discharge circuit that electrically connects adjacent bipolar electrodes is formed in the same plane of at least one of the positive electrode layer, the negative electrode layer, or the electrolyte layer. . 2. The bipolar battery according to claim 1, wherein a contact area of the discharge circuit with the bipolar electrode is 0.06 mm ² or more with respect to a battery capacity of 1 Ah of the bipolar battery. The discharge voltage threshold in the discharge circuit is set between 3.6 V and 4.1 V, and the doping concentration is 10 ¹⁷ to 10 to make the breakdown voltage of the PN junction of the discharge circuit the same as the threshold setting. ¹⁸ in the range of, also empty亡層thickness bipolar battery according to claim 1, characterized in that the range of 0.1Myuemu～1.0Myuemu.   The bipolar battery according to claim 1, wherein the discharge circuit includes a Zener diode layer.   The bipolar battery according to claim 1, wherein the discharge circuit includes a light emitting layer, and an optical sensor that is sensitive to light from the light emitting layer is provided in the vicinity of the discharge circuit. 6. The bipolar battery according to claim 5, wherein a light guide layer is disposed between the light emitting layer and an end of the battery.   The bipolar battery according to claim 5, wherein the discharge circuit includes a constant current circuit.   The bipolar battery according to any one of claims 1 to 4, wherein the bipolar electrode, the electrolyte layer, and the discharge circuit are covered and sealed with an exterior material.   The bipolar battery according to claim 6, wherein the bipolar electrode, the electrolyte layer, the discharge circuit, and the optical sensor are covered and sealed with an exterior material.   An assembled battery comprising a plurality of the bipolar batteries according to claim 1 connected to each other.   A vehicle comprising the bipolar battery according to claim 1 or the assembled battery according to claim 10 as a power source.

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