JP2005340089A - Bipolar battery, assembled battery, and vehicle equipped with the batteries - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bipolar battery capable of improving power output, heat radiation, heat resistance and vibration resistance. <P>SOLUTION: This bipolar battery 10 comprises a bipolar electrode 16 that is formed by forming a positive electrode-active material layer 12 on one side of a collector 11 and a negative electrode-active material layer 13 on the other side, and a separator 14 that is alternately laminated with a bipolar electrode 16 and contains electrolytes, wherein in a single cell 15 that is composed by stacking a positive electrode-active material layer 12, a separator 14, and a negative electrode-active material layer 13 in order, at least either one of the positive electrode-active material layer 12 or the negative electrode-active material layer 13 is thinner than the separator 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bipolar battery, an assembled battery in which a plurality of bipolar batteries are connected, and a vehicle equipped with these batteries.

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

  A bipolar battery includes a battery element in which bipolar electrodes and electrolyte layers are alternately stacked. The bipolar electrode is formed by forming a positive electrode active material layer on one surface of a current collector and forming a negative electrode active material layer on the other surface.

Many such bipolar batteries have been conventionally designed for high capacity. For this reason, the positive electrode active material layer and the negative electrode active material layer are formed thicker than the electrolyte layer. Alternatively, no particular attention is paid to the ratio of the thicknesses of the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer (see, for example, Patent Document 1 and Patent Document 2).
Japanese Patent Laid-Open No. 2000-1000047 JP 2000-195495 A

  However, as described above, when the positive electrode active material layer and the negative electrode active material layer are thick, there is a problem that diffusion resistance and ion transfer resistance of the portion become large, thereby preventing achievement of high output.

  In addition, the positive electrode active material layer and the negative electrode active material layer having high diffusion resistance and ion transfer resistance generate a large amount of heat, and heat hardly escapes to the outside. For this reason, there exists a problem that heat dissipation is low and heat resistance is weak.

  When a bipolar battery is mounted on a vehicle, it is desired to have a vibration-proof property capable of withstanding the vibration of the vehicle. However, if the positive electrode active material layer and the negative electrode active material layer are thicker than the electrolyte layer, there is a problem that the vibration proof property is low and vibration isolation is low.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bipolar battery, an assembled battery, and a vehicle equipped with these that can improve output, heat dissipation, heat resistance, and vibration isolation.

  (1) The bipolar battery of the present invention is formed by alternately laminating a bipolar electrode having a positive electrode active material layer formed on one surface of a current collector and a negative electrode active material layer formed on the other surface, and the bipolar electrode. A separator for holding an electrolyte, and a single battery layer including the positive electrode active material layer, the separator, and the negative electrode active material layer adjacent to each other, wherein the positive electrode active material layer and the negative electrode active material At least one of the layers is thinner than the separator.

  (2) The assembled battery of the present invention is formed by connecting a plurality of the bipolar batteries of the above (1).

  (3) The vehicle of the present invention includes the bipolar battery of (1) or the assembled battery of (2) as a driving power source.

  According to the bipolar battery of (1) above, at least one of the positive electrode active material layer and the negative electrode active material layer is thinner than the separator, so that the diffusion resistance and the ion transfer resistance are small, and a high output bipolar battery is obtained. It is done.

  Furthermore, in the bipolar battery of the present invention, since the resistance is small, the calorific value is small. In addition, since the positive electrode active material layer and the negative electrode active material layer are thin, the central portion of the positive electrode active material layer and the negative electrode active material layer where heat is stored is close to a metallic current collector with excellent heat dissipation, so that heat is smooth It moves to the current collector and efficiently dissipates heat. A bipolar battery with improved heat dissipation is obtained.

  In addition, in the bipolar battery of the present invention, since at least one of the positive electrode active material layer and the negative electrode active material layer is thinner than the separator, vibration of the bipolar electrode can be absorbed by the separator. A bipolar battery with improved vibration isolation is obtained.

  According to the assembled battery of (2) above, a high capacity and high output can be obtained by connecting a plurality of bipolar batteries, and the reliability of each bipolar battery is high. Can be improved.

  According to the vehicle of the above (3), it is possible to provide a compact vehicle power source having various characteristics such as the bipolar battery of the above (1) or the assembled battery of the above (2).

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, each component is exaggerated for clarity of explanation.

(First embodiment)
FIG. 1 is a cross-sectional view showing the structure of a battery element for a bipolar battery.

  FIG. 1 is a cross-sectional view for explaining the structure of a bipolar battery to which the present invention is applied.

  In the bipolar battery 10 of the present invention, a positive electrode active material layer 12 and a negative electrode active material layer 13 are formed at the center of both surfaces of a current collector 11 other than both ends, and the positive electrode active material layer 12 and the negative electrode of the current collector 11 are formed. A single cell layer 15 is formed with a separator 14 interposed between the active material layer 13 and a plurality of the single cell layers 15 are stacked in the same order. A material in which the positive electrode active material layer 12 is formed on one surface of the current collector 11 and the negative electrode active material layer 13 is formed on the other surface is referred to as a bipolar electrode 16. A current collector (referred to as an end current collector 17) at both ends is connected to electrodes of the entire bipolar battery.

  A structure in which the positive electrode active material layer 12 and the negative electrode active material layer 13 are provided with the current collector 11 interposed therebetween is called a bipolar electrode.

  Here, the separator 14 is, for example, a polymer skeleton formed of a resin selected from the group consisting of a polyester resin, an aramid resin, and a polyolefin resin, either alone or in combination. The separator 14 constitutes an electrolyte layer by holding a gel electrolyte or a liquid electrolyte containing an electrolytic solution of about several to 98% by weight. Moreover, the separator 14 can also hold | maintain an electrolyte by being formed with a solid electrolyte itself. In the first embodiment, a case where a gel electrolyte is held in the separator 14 will be described.

  When the separator 14 holds the gel electrolyte, in order to prevent liquid leakage from the single cell layer 15, it surrounds each single cell layer 15 and is between the current collectors 11 or between the current collectors 11 and the end portions. A seal member 18 disposed between the current collectors 17 is provided.

  The seal member 18 is, for example, a double-sided tape in which an adhesive material is applied to both surfaces of a base material. The base material is formed of an insulating resin such as polypropylene (PP), polyethylene (PE), or polyamide synthetic fiber. The pressure-sensitive adhesive is formed of a solvent-resistant material such as synthetic rubber, butyl rubber, synthetic resin, or acrylic. By using such a material for the seal member 18, it is possible to prevent liquid leakage from the single cell layer 15 and to prevent a short circuit due to contact between the current collectors.

  As described above, the separators 14 and the bipolar electrodes 16 are alternately stacked, and the sealing member 18 is disposed around the unit cell layer 15 to form the battery element 20.

  The battery element 20 is connected to electrode tabs 30a and 30b for drawing current. The electrode tab 30a is connected to the positive electrode side of the battery element 20, and the electrode tab 30b is connected to the negative electrode side. The battery element 20 is sealed with an exterior 40.

  The exterior 40 is formed by two laminate sheets 41. The laminate sheet 41 has a three-layer structure in which both surfaces of an aluminum layer are covered with a resin layer. At least one of the laminate sheets 41 is processed into a medium-high shape in order to provide a space that encloses the battery element 20. The edge of the laminate sheet 41 is bonded by heat fusion or the like. Thereby, the battery element 20 is sealed inside the exterior 40.

  The feature of the present invention resides in the thickness, material, hardness and the like of each layer constituting the battery element. These features will be described.

(thickness)
FIG. 2 is a diagram showing battery elements, and FIG. 3 is a diagram comparing the single cell layer of the present invention with a conventional single cell layer.

  As described above, the battery element 20 is formed by laminating a plurality of unit cell layers 15 including the positive electrode active material layer 12, the negative electrode active material layer 13, the separator 14, and the current collector foil 11. FIG. 2 shows a battery element 20 in which three cell layers are stacked.

  In the conventional unit cell, as shown on the left side of FIG. 3, the thickness of the positive electrode active material layer 12 'and the negative electrode active material layer 13' is 2-5 times the thickness of the separator 14 ', which is very thick. For example, the thickness of the positive electrode active material layer 12 ′ and the negative electrode active material layer 13 ′ was 50 to 100 μm, while the thickness of the separator 14 ′ was 20 to 40 μm.

  In the battery element 20 of the first embodiment, as shown on the right side of FIG. 3, the thickness of at least one of the positive electrode active material layer 12 and the negative electrode active material layer 13 is equal to or less than the thickness of the separator 14. While satisfying this, for example, the thickness of the positive electrode active material layer 12 and the negative electrode active material layer 13 is 4 to 35 μm, and the thickness of the separator 14 is 5 to 40 μm.

  The thickness of at least one of the positive electrode active material layer 12 and the negative electrode active material layer 13 is preferably 0.5 to 1.0 times the thickness of the separator 14.

  This is because when the thickness of the positive electrode active material layer 12 and the negative electrode active material layer 13 is 0.5 times or less than the thickness of the separator 14, the capacity of the unit cell layer 15 becomes too small and is difficult to use for general purposes. .

  The total thickness of the unit cell layers 15 is preferably 100 μm or less. For example, the current collector 11 has a thickness of about 10 to 15 μm, the positive electrode active material layer 12 has a thickness of 25 to 30 μm, the negative electrode active material layer 13 has a thickness of 25 to 30 μm, and the separator 14 has a thickness of 25. The thickness of the current collector 11 is about 10 to 15 μm, and the thickness of each layer is adjusted so that the total thickness of the unit cell layers 15 is 100 μm or less.

  FIG. 4 is a diagram showing a mass spring model of the battery element.

  As shown in FIG. 4, the battery element 20 can be considered as a vibration system model in which masses 31, springs 32, and dampers 33 are alternately arranged.

  In this model, the bipolar electrode 16 corresponds to the mass 31, and the separator 14 corresponds to the spring 32 and the damper 33.

  Here, as in the conventional structure shown on the left side of FIG. 3, when the positive electrode active material layer 12 ′ and the negative electrode active material layer 13 ′ are thick, the mass 31 is larger than the spring 32 and the damper 33. In this case, the mass 31 having a large mass is likely to vibrate, and is difficult to absorb the vibration by the spring 32 and the damper 33.

  On the other hand, when the positive electrode active material layer 12 and the negative electrode active material layer 13 are thin as in the present embodiment shown on the right side of FIG. 3, the spring 32 and the damper 33 can suppress the vibration of the mass 31 and absorb the vibration. .

  Thus, by adjusting the thickness of each layer, the battery element 20 can be balanced and vibration can be suppressed.

  In FIG. 4, the hardness of each separator 14 is equal in each layer, and when modeled, the spring coefficient K of the spring 32 in each layer and the damping coefficient C of the damper 33 are equal. The battery element 20 having the same hardness of the separator 14 is hereinafter referred to as the invention structure 1.

  Further, with respect to the thickness of each layer, the thickness of the separator 14 is more preferably 20 μm or less. This is because by setting the separator 14 to 20 μm or less, the internal resistance of the separator is lowered and heat generation is reduced. By making the separator 14 thinner, heat is less likely to stay inside the separator 14 and is immediately transmitted to the current collector 11, so that heat dissipation is also improved.

  Regarding the thickness of each layer, more preferably, the total thickness of the unit cell layers 15 is preferably 50 μm or less. The thickness of the current collector 11 is about 10 to 15 μm. The positive electrode active material layer 12 has a thickness of 4 to 11 μm, the negative electrode active material layer 13 has a thickness of 6 to 13 μm, and the separator 14 has a thickness of 7 to 15 μm. The thickness of each layer is adjusted so as to be 50 μm or less.

(hardness)
The separator 14 has a hardness in the range of 20 to 110 in terms of hardness JIS-A. Preferably, it is in the range of 25-95 in hardness JIS-A. The reason is as follows.

  This is because when the hardness is JIS-A20 or less, the separator is too soft, the frequency at which the battery element 20 resonates is on the low frequency side, and resonates with vibrations of 100 Hz or less that may occur on the vehicle. Resonance may cause destruction of battery elements. Moreover, it is too hard in JIS-A110 or higher, and when the above vibration system model is used, the functions of the spring 32 and the damper 33 are not exhibited, and the vibration isolation effect cannot be obtained.

  Moreover, it is preferable that the hardness of the separator 14 is not uniform in all the layers. Usually, since the same material is used in each layer, each mass 31, spring 32, and damper 33 are equal when replaced with a vibration system model. However, the vibration-proof performance can be further improved by making the hardness of some separators 14 different from others.

  In order to improve the anti-vibration performance, it is preferable that the hardness of the separator disposed outside the stack is higher than the hardness of the separator disposed inside the stack. FIG. 5 shows a vibration system model in this case.

  FIG. 5 is a diagram showing a mass spring model of the battery element.

  The battery element 50 shown in FIG. 5 includes a bipolar electrode 16 similar to that in FIG. In FIG. 5, the hardness of the separators 51 and 52 sandwiched between the bipolar electrodes 16 is different. The separator 51 disposed outside the stack has a higher hardness than the separator 52 disposed inside the stack.

  As shown in FIG. 5, the battery element 50 is modeled as a vibration system including a mass 31, springs 53 and 54, and dampers 55 and 56.

The mass 31 is composed of a bipolar electrode 16 (with the positive electrode active material layer 12 formed on one side of the current collector 11 and the negative electrode active material layer 13 formed on the other side). The thickness of the current collector 12 can be changed, the thickness of the negative electrode active material 13 can be changed, or the thickness of the current collector 11 can be changed.
The spring coefficient of the spring 53 is K1, the spring coefficient K2 of the spring 54, the damping coefficient of the damper 55 is C1, and the damping coefficient of the damper 56 is C2. Then, K1> K2 and C1 <C2. The inner side of the stack has a lower spring coefficient and higher damping performance.

  Thus, by reducing the hardness of the separator 52 on the inner side of the stack, the frequency at which the battery element 50 resonates can be shifted to the high frequency side, and the peak height of the vibration can be reduced. When the battery element 50 is mounted on a vehicle, the battery element 50 can exhibit more anti-vibration performance.

  Further, by reducing the hardness of the separator 52 on the inner side of the stack, the heat dissipation property on the inner side where heat is most likely to be stored in the battery element 50 can be enhanced.

  Hereinafter, the battery element 50 in which the hardness of the separator 52 on the inner side of the stack is low is referred to as the invention structure 2.

(material)
The separator 14 is made of a resin selected from the group consisting of polyester resins, aramid resins, and polyolefin resins, either alone or in combination. In order to make the separator 14 thin, an aramid type is preferable, but not limited thereto. A porous structure can be formed by forming a separator with these materials. In addition to these, a resin having a waterproof property, a moisture proof property, a thermal cycle property, a heat stability, and an insulating property can be used for the separator.

  Both the positive electrode active material constituting the positive electrode active material layer 12 and the negative electrode active material constituting the negative electrode active material layer preferably have an average particle diameter of 2 μm or less. This is because in the first embodiment, the positive electrode active material layer 12 and the negative electrode active material layer 13 are made thinner than conventional ones. In particular, when the thickness of the separator 14 is 20 μm or less, the uniform positive electrode active material layer 12 and the negative electrode active material layer 13 are required unless the average particle size of the positive electrode active material and the negative electrode active material is about 1/10 of the thickness of the separator 14. It is difficult to form the surface. If the surface is not uniform, the separator 14 may not be able to absorb the irregularities on the electrode surface, so it is necessary to limit the average particle size to 2 μm or less.

  The thickness, hardness, and material of each layer have been described above. Next, the results of experiments on how the above-described invention structure 1 and invention structure 2 of the battery element differ from the structure of the conventional battery element will be shown.

  6 is a diagram showing the relationship between time and temperature when the battery element is energized, and FIG. 7 is a diagram showing the relationship between the frequency of vibration applied to the battery element and the vibration transmissibility.

  As shown on the left side of FIG. 3, a battery element having a conventional structure in which a plurality of conventional unit cell layers 15 ′ having a thick positive electrode active material layer 12 ′ and negative electrode active material layer 13 ′ are stacked on the separator 14 ′, The above-described battery element 20 of the inventive structure 1 and 50 of the inventive structure 2 were prepared.

  As a first experiment, the same amount of current was passed through each of the conventional structure, the inventive structure 1 and the inventive structure 60 for 60 minutes, and then the heat dissipation was examined by temperature change.

  Then, as shown in FIG. 6, in the conventional structure, the temperature rose to about 55 degrees. Even after 40 minutes had passed since the energization was stopped, the temperature did not return to room temperature.

  On the other hand, in Invention Structure 1, the temperature rose to about 43 degrees when the energization was stopped, but it returned to room temperature when 10 minutes had passed since the energization was stopped.

  In Invention Structure 2, the temperature rose only to about 34 degrees when the energization was stopped, and returned to room temperature in about 5 minutes after the energization was stopped.

  Referring to the experimental results shown in FIG. 6, it can be seen that the conventional structure has a larger temperature rise than the invention structure 1 and the invention structure 2, and the heat dissipation may not be sufficient. This is because the positive electrode active material layer 12 ′ and the negative electrode active material layer 13 ′ are thick, so that the resistance is large and the heat generation amount is large, and the generated heat is accumulated and is not easily radiated.

  In Invention Structure 1, since the positive electrode active material layer 12 and the negative electrode active material layer 13 are thinner than the separator 14, the electric resistance is small and the heat generation amount is small, and the generated heat is quickly transmitted to the current collector 11 and the like to be dissipated. ing.

  In Invention Structure 2, since the separator 52 on the inner side of the laminated structure is soft, the heat radiation property on the inner side where heat is most likely to be stored in the laminated structure is enhanced, and the temperature rise is lower than that of Invention Structure 1 and the heat radiation time is also shortened.

  Next, as a second experiment, vibrations with different frequencies were applied to the conventional structure, the inventive structure 1, and the inventive structure 2, and the frequency of resonance was examined.

  Then, as shown in FIG. 7, the conventional structure resonated mainly with low-frequency vibrations of 100 Hz or less.

  On the other hand, Invention Structure 1 and Invention Structure 2 resonated with high-frequency vibrations of about 200 Hz at 100 Hz or higher. In particular, the invention structure 2 had a lower vibration transmissibility than the invention structure 1 even at the same frequency. This is because, in the invention structure 2, the hardness of the separator 52 on the inner side of the stack is lower than that on the outer side of the stack, so that the anti-vibration performance is higher than that of the invention structure 1 as described above.

  As described above, according to the bipolar battery 10 of the present invention, at least one of the positive electrode active material layer 12 and the negative electrode active material layer 13 is smaller in thickness than the separator 14, so that the diffusion resistance and the ion transfer resistance are small. A high output bipolar battery 10 is obtained.

  Furthermore, in the bipolar battery 10 of the present invention, since the resistance is small, the calorific value is small. Further, since the positive electrode active material layer 12 and the negative electrode active material layer 13 are thin, the central portions of the positive electrode active material layer 12 and the negative electrode active material layer 13 where heat is stored are close to the metallic current collector 11 having excellent heat dissipation. Therefore, heat moves smoothly to the current collector 11 and is efficiently radiated. A bipolar battery 10 with improved heat dissipation is obtained.

  In addition, in the bipolar battery 10 of the present invention, since at least one of the positive electrode active material layer 12 and the negative electrode active material layer 13 is thinner than the separator, vibration of the bipolar electrode 10 can be absorbed by the separator 14. A bipolar battery 10 with improved vibration isolation is obtained.

  The configuration of the bipolar battery of the present invention is not particularly limited as long as a known material used for a general lithium ion secondary battery is used, except for those specifically described. The current collector, positive electrode active material layer, negative electrode active material layer, electrolyte, and the like that can be used for this bipolar battery will be described below for reference.

[Current collector]
The current collector has a surface material of SUS. When the surface material is SUS, even if the formed active material layer contains a solid polymer electrolyte, the active material layer has high mechanical strength. If the surface material is SUS, the structure will not be specifically limited. The current collector may be SUS itself. Further, the surface of the current collector may be covered with SUS. That is, a current collector in which SUS is coated on the surface of a substance other than SUS (such as titanium, YUS, or an alloy thereof) may be used. Depending on the case, you may use the electrical power collector which bonded together the 2 or more board by which the positive electrode side becomes aluminum and the negative electrode side becomes copper. From the viewpoint of corrosion resistance, ease of production, economy, etc., it is preferable to use a SUS foil alone as a current collector.

[Positive electrode active material layer]
The positive electrode active material layer includes a positive electrode active material and a solid polymer electrolyte. In addition to this, a supporting salt (lithium salt) for increasing ionic conductivity, a conductive auxiliary agent for increasing electronic conductivity, NMP (N-methyl-2-pyrrolidone) as a solvent for adjusting slurry viscosity, a polymerization initiator AIBN (azobisisobutyronitrile) and the like may be included.

As the positive electrode active material, a composite oxide of lithium and a transition metal, which is also used in a solution-type lithium ion battery, can be used. Specifically, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, Li · Mn-based composite oxide such as spinel LiMn ₂ O _4, Li · such LiFeO ₂ Examples thereof include Fe-based composite oxides. In addition, transition metal and lithium phosphate compounds and sulfuric acid compounds such as LiFePO ₄ ; transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ ; PbO ₂ , AgO, NiOOH etc. are mentioned. By using a lithium-transition metal composite oxide as the positive electrode active material layer active material, the reactivity and cycle durability of the stacked battery can be improved and the cost can be reduced. When a Li · Mn-based composite oxide is used, the reaction is gentle even when the battery fails due to overcharge or overdischarge, and the reliability at the time of abnormality is high.

The solid polymer electrolyte is not particularly limited as long as it is a polymer having ion conductivity. Examples of the polymer having ion conductivity include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. Such polyalkylene oxide polymers can well dissolve lithium salts such as LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) ₂ . Moreover, excellent mechanical strength is exhibited by forming a crosslinked structure. In the present invention, the solid polymer electrolyte is contained in at least one of the positive electrode active material layer and the negative electrode active material layer. However, in order to further improve the battery characteristics of the bipolar battery, it is preferable to be included in both.

As the supporting salt, Li (C ₂ F ₅ SO ₂ ) ₂ N, LiBF ₄ , LiPF ₆ , LiN (SO ₂ C ₂ F ₅ ) ₂ , or a mixture thereof can be used. However, it is not necessarily limited to these.

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

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

Here, the case where a bipolar battery giving priority to battery reactivity is manufactured using a solid polymer electrolyte (ionic conductivity: 10 ⁻⁵ to 10 ⁻⁴ S / cm) at the current level will be specifically considered. In order to obtain a bipolar battery having such characteristics, the electron conduction resistance between the active material particles is kept low by increasing the conductive auxiliary agent or reducing the bulk density of the active material. At the same time, the gap is increased, and the gap is filled with a solid polymer electrolyte. The ratio of the solid polymer electrolyte may be increased by such treatment.

  The thickness of the positive electrode active material layer is not particularly limited, and should be determined in consideration of the intended use of the battery (such as emphasis on output and energy) and ion conductivity, as described for the blending amount.

[Negative electrode active material layer]
The negative electrode active material layer includes a negative electrode active material and a solid polymer electrolyte. In addition to this, a supporting salt (lithium salt) for increasing ionic conductivity, a conductive auxiliary agent for increasing electronic conductivity, NMP (N-methyl-2-pyrrolidone) as a solvent for adjusting slurry viscosity, a polymerization initiator AIBN (azobisisobutyronitrile) and the like may be included. Except for the type of the negative electrode active material, the contents are basically the same as those described in the section “Positive electrode active material”, and thus the description thereof is omitted here.

  As the negative electrode active material, a negative electrode active material that is also used in a solution-type lithium ion battery can be used. The negative electrode active material is preferably selected from a crystalline carbon material and an amorphous carbon material. By using these materials, the state of charge can be examined by measuring the voltage. Since it is possible to detect and deal with overcharge and overdischarge conditions, the reliability of the battery can be improved. This effect is remarkable in an amorphous carbon material.

[Electrolyte layer]
The material is not limited as long as it is a layer composed of a polymer having ion conductivity and exhibits ion conductivity. It is preferable to use a solid electrolyte for preventing liquid leakage. Examples of the solid electrolyte include known solid polymer electrolytes such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. The solid polymer electrolyte layer contains a supporting salt (lithium salt) in order to ensure ionic conductivity. As the supporting salt, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , or a mixture thereof can be used. However, it is not necessarily limited to these. A polyalkylene oxide polymer such as PEO and PPO can dissolve lithium salts such as LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) ₂ well. Moreover, excellent mechanical strength is exhibited by forming a crosslinked structure.

The polymer gel electrolyte generally refers to an electrolyte solution held in an all-solid polymer electrolyte having ion conductivity. The electrolytic solution (electrolyte salt and plasticizer) is not particularly limited, and various conventionally known electrolytic solutions can be appropriately used. For example, inorganic acid anion salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N or more selected from organic acid anion salts, including at least one lithium salt (electrolyte salt), cyclic carbonates such as propylene carbonate and ethylene carbonate; dimethyl carbonate, Chain carbonates such as methyl ethyl carbonate and diethyl carbonate; ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane; γ-butyrolactone, etc. Lactones; Nitriles such as acetonitrile Esters such as methyl propionate; amides such as dimethylformamide; plasticizers such as aprotic solvents (organic solvents) mixed with at least one selected from methyl acetate and methyl formate ) Can be used. However, it is not necessarily limited to these.

[Laminate sheet]
The laminate sheet is used as a battery exterior material. In general, a polymer metal composite film in which a heat-fusible resin film, a metal foil, and a resin film having rigidity are laminated in this order is used.

  As the heat-fusible resin, for example, polyethylene (PE), polypropylene (PP), modified polyethylene, modified polypropylene, ionomer, ethylene vinyl acetate (EVA) and the like can be used. As the metal foil, for example, Al foil or Ni foil can be used. As the resin having rigidity, polyamide synthetic fibers such as polyester such as polyethylene terephthalate (PET) and polyamide (nylon (registered trademark)) can be used. Specifically, a PE / Al foil / PET laminated film laminated from the sealing surface side to the outer surface; a PE / Al foil / nylon (registered trademark) laminated film; an ionomer / Ni foil / PET laminated film; EVA / Al foil / PET laminated film; ionomer / Al foil / PET laminated film and the like can be used. The heat-fusible resin film acts as a seal layer when the battery element is housed inside. A metal foil or a rigid resin film imparts moisture, breathability, and chemical resistance to the exterior material. The laminate sheet can be easily and reliably bonded using heat sealing such as heat sealing, impulse sealing, ultrasonic welding, and high-frequency welding.

(First embodiment)
Next, an example in which a bipolar battery that actually employs the configuration of the battery element described above was manufactured and evaluated will be described.

<Sample preparation>
As examples, bipolar batteries of Examples 1 to 6 having different specifications were prepared.

  8 and 9 are diagrams showing the specifications of the bipolar batteries of Examples 1-6. In Examples 1 to 6, bipolar batteries were manufactured based on the specifications shown in FIGS. 8 and 9 so that the single battery layer was one layer. The detailed configuration of each embodiment is as follows.

(Example 1)
Two stainless steel (SUS) foils having a thickness of 20 μm were prepared as end collectors disposed at both ends of the laminate. On one side of one end current collector, a positive electrode active material having an average particle size of 5 μm and made of a Li / Mn-based composite oxide is applied and dried so as to have a thickness of 15 μm. Formed. This was used as a positive electrode.

  On the other end current collector, a negative electrode active material having an average particle diameter of 6 μm and made of an amorphous carbon material was applied and dried so as to have a thickness of 15 μm to form only the negative electrode active material layer. This was used as a negative electrode.

  A battery element having a one-layer structure was formed by sandwiching an electrolyte layer in which a precursor of a cross-linked gel electrolyte was soaked in a polyester nonwoven fabric separator having a thickness of 25 μm and a hardness of JIS-A 60 between these electrodes.

The total thickness of the battery elements was 70 μm. At this time, the value obtained by dividing the thickness of the positive electrode active material layer by the thickness of the separator was 0.60. Moreover, it was 27 ohm-cm < ² > when the internal resistance of the battery element was measured.

  An aluminum tab having a thickness of 100 μm and a width of 100 mm was vibration welded on the positive electrode end side of the battery element, and a copper tab having a thickness of 100 μm and a width of 100 mm was vibration welded on the negative electrode end side. This was sealed with a laminate material and heated and cross-linked at about 80 ° C. for about 2 hours to obtain a bipolar battery of Example 1.

  In the following Examples 2 to 6, bipolar batteries were produced by the same manufacturing process as in Example 1. In Examples 2 to 6, only the thickness and material of each layer will be described.

(Example 2)
In Example 2, the current collector was formed of a stainless steel foil having a thickness of 15 μm. The positive electrode active material layer was formed to a thickness of 27 μm by using a Li · Mn composite oxide having an average particle diameter of 5 μm. The negative electrode active material layer was formed to a thickness of 28 μm from an amorphous carbon material having an average particle diameter of 6 μm. A polyester nonwoven fabric having a thickness of 30 μm and a hardness of JIS-A 30 was used for the separator.

The total thickness of the battery element was 100 μm. A value obtained by dividing the thickness of the positive electrode active material layer by the thickness of the separator was 0.90. Moreover, it was 30 ohm-cm < ² > when the internal resistance of the battery element was measured.

(Example 3)
In Example 3, the current collector was formed of a clad plate of copper and aluminum having a thickness of 15 μm. The positive electrode active material layer was formed to a thickness of 33 μm by using a Li · Mn composite oxide having an average particle diameter of 8 μm. The negative electrode active material layer was formed to a thickness of 35 μm from a crystalline carbon material having an average particle size of 9 μm. A polyolefin nonwoven fabric having a thickness of 37 μm and a hardness of JIS-A 85 was used as the separator.

The total thickness of the battery element was 120 μm. A value obtained by dividing the thickness of the positive electrode active material layer by the thickness of the separator was 0.89. Moreover, it was 33 ohm-cm < ² > when the internal resistance of the battery element was measured.

Example 4
In Example 4, the current collector was formed of a stainless steel foil having a thickness of 15 μm. The positive electrode active material layer was formed to a thickness of 11 μm using a Li · Mn composite oxide having an average particle diameter of 2 μm. The negative electrode active material layer was formed to a thickness of 11 μm using an amorphous carbon material having an average particle diameter of 2 μm. As the separator, an aramid nonwoven fabric having a thickness of 13 μm and a hardness of JIS-A 90 was used.

The total thickness of the battery element was 50 μm. A value obtained by dividing the thickness of the positive electrode active material layer by the thickness of the separator was 0.85. Moreover, it was 23 ohm-cm < ² > when the internal resistance of the battery element was measured.

(Example 5)
In Example 5, the current collector was formed of a stainless steel foil having a thickness of 15 μm. The positive electrode active material layer was formed to a thickness of 7.5 μm using a Li / Ni composite oxide having an average particle diameter of 2 μm. The negative electrode active material layer was formed to a thickness of 12 μm using an amorphous carbon material having an average particle diameter of 2 μm. As the separator, an aramid nonwoven fabric having a thickness of 13 μm and a hardness of JIS-A 90 was used.

The total thickness of the battery element was 47.5 μm. A value obtained by dividing the thickness of the positive electrode active material layer by the thickness of the separator was 0.58. Moreover, it was 23 ohm-cm < ² > when the internal resistance of the battery element was measured.

(Example 6)
In Example 6, the current collector was formed of a stainless steel foil having a thickness of 15 μm. The positive electrode active material layer was formed to a thickness of 4 μm using a Li / Ni composite oxide having an average particle diameter of 0.8 μm. The negative electrode active material layer was formed to a thickness of 6 μm using an amorphous carbon material having an average particle size of 0.8 μm. As the separator, an aramid nonwoven fabric having a thickness of 7 μm and a hardness of JIS-A 105 was used.

The total thickness of the battery element was 27 μm. A value obtained by dividing the thickness of the positive electrode active material layer by the thickness of the separator was 0.57. Moreover, it was 20 ohm-cm < ² > when the internal resistance of the battery element was measured.

(Comparative Example 1)
As Comparative Example 1, a bipolar battery was manufactured by the same manufacturing process as in Example 1 above. In the bipolar battery of Comparative Example 1, the current collector was formed of a stainless steel foil having a thickness of 15 μm. The positive electrode active material layer was formed to a thickness of 50 μm using a Li · Mn composite oxide having an average particle diameter of 5 μm. The negative electrode active material layer was formed to a thickness of 60 μm from an amorphous carbon material having an average particle diameter of 6 μm. As the separator, a polyester nonwoven fabric having a thickness of 25 μm and a hardness of JIS-A 60 was used.

The total thickness of the battery element was 150 μm. A value obtained by dividing the thickness of the positive electrode active material layer by the thickness of the separator was 2.00. Moreover, it was 60 ohm-cm < ² > when the internal resistance of the battery element was measured.

<Test>
The following tests were performed on the bipolar batteries of Examples 1 to 6 and Comparative Example 1 manufactured as described above.

(Resonance frequency measurement)
An acceleration pickup was provided at substantially the center of the single cell layer of the battery element, and the vibration spectrum of the acceleration pickup when hammered by an impulse hammer was measured. Various settings for the measurement were in accordance with JIS B 0908 (vibration and shock pickup calibration method / basic concept).

  The measured spectrum was analyzed with an FFT analyzer and converted to frequency and acceleration dimensions. The obtained frequency was averaged and smoothed to obtain a vibration transmissibility spectrum (see FIG. 7).

  About the said vibration transmissibility spectrum, about each said Examples 1-6 and the comparative example 1, the maximum peak frequency which appears on the lowest frequency side was calculated | required, respectively. Hereinafter, the maximum peak frequency is referred to as a first resonance peak.

(Measurement of vibration damping rate)
For the vibration transmissibility spectrum obtained in the above “resonance frequency measurement”, the average of the vibration transmissibility up to 10 to 300 Hz was calculated. Hereinafter, this average value is referred to as a vibration average value. Based on the vibration average value in the case of the conventional structure of Comparative Example 1, how much the vibration average value of each of Examples 1 to 6 was reduced was examined. The rate of reduction is expressed as a percentage. For example, when the average damping rate is 0%, the average vibration value is the same as that of Comparative Example 1, indicating that no damping has occurred. Further, for example, when the average vibration rate is 30%, it indicates that the vibration average value of the example is reduced by 30% with respect to Comparative Example 1.

(Measurement of heat rise and heat dissipation time)
A thermocouple was attached to the edge of the current collector of the battery element, a 10C cycle test was conducted for 60 minutes, and the maximum temperature reached for the battery element under test was measured as a heat rise. In addition, after a cycle test for 60 minutes, the current was stopped and the temperature change when left at room temperature was examined, and the time until returning to room temperature was measured. The measurement was performed for a maximum of 60 minutes, and when it did not return to room temperature in 60 minutes, it was recorded in the measurement result as 60 minutes or more.

  The test results are summarized as shown in FIG.

<Test results>
FIG. 10 is a diagram showing test results.

  In the test results, reference is made to the first resonance peak. In Comparative Example 1, the first resonance peak was 80 Hz, which was within the range of frequencies that can be generated on the vehicle (100 Hz or less). Therefore, in Comparative Example 1, it was found that when mounted on a vehicle, resonance occurred.

  On the other hand, in Examples 1-6, it turned out that a 1st resonance peak is 100 Hz or more, and even if it mounts in a vehicle, it does not resonate.

  Refer to the vibration damping rate in the test results. The vibration damping rate of each of Examples 1 to 6 was 30% or more, and it was found that the vibration can be significantly damped with respect to Comparative Example 1 having a conventional structure. Among Examples 1 to 6, the vibration damping rate of Example 6 was the highest. This is because in Example 6, the positive electrode active material layer and the negative electrode active material layer were the thinnest and the total thickness was also thin, so that the battery elements were balanced. From this, it can be seen that the battery element preferably has a positive electrode active material layer and a negative electrode active material layer formed thinly to form a total thickness.

  Refer to heat rise in the test results. The heat rise was 20 δT at maximum in Example 3 among Examples 1-6. However, compared with 30 δT of Comparative Example 1, it was found that the temperature increase was reduced to 2/3. Among Examples 1-6, the heat rise of Example 6 was the lowest. This is because in Example 6, the positive electrode active material layer and the negative electrode active material layer were the thinnest and the internal resistance was the lowest, so the calorific value was smaller than those in other Examples 1-5. In addition, it is considered that the increase in heat was small because heat was not trapped in the positive electrode active material layer and the negative electrode active material layer and was radiated through the current collector even during energization.

  Refer to the heat release time in the test results. The heat dissipation time was 60 minutes or more in the comparative example, whereas in Examples 1 to 6, it was 15 minutes at the maximum. From this result, it can be seen that, as in Examples 1 to 6, the heat dissipation characteristics are remarkably improved by reducing the thickness of the positive electrode active material layer and the negative electrode active material layer as compared with the conventional structure. Regarding the heat dissipation time, Example 6 was the shortest.

  As described above, in each of Examples 1 to 6, the positive electrode active material layer and the negative electrode active material layer were made thinner than the conventional structure, so that heat dissipation, heat resistance, and prevention were reduced as compared with Comparative Example 1 of the conventional structure. It can be seen that the vibration is improved. In addition, in Examples 1-6, since the internal resistance of the battery element is much smaller than the internal resistance of the battery element of Comparative Example 1, the output can also be improved.

(Second embodiment)
In the first example, an experiment was performed using only a bipolar battery having a single cell layer. On the other hand, in the second example, a bipolar battery having a battery element in which a plurality of single battery layers of any of the bipolar batteries of Examples 1 to 6 were stacked was manufactured.

(Example 7)
In Example 7, a bipolar battery having a battery element in which three single battery layers of Example 1 were laminated was manufactured. The detailed manufacturing process is as follows.

  A stainless steel (SUS) foil having a thickness of 20 μm was used as a current collector. On one side of the current collector, a positive electrode active material having an average particle diameter of 5 μm and made of a Li / Mn composite oxide was applied and dried to a thickness of 15 μm to form a positive electrode active material layer.

  Furthermore, on the other surface of the current collector, a negative electrode active material made of an amorphous carbon material having an average particle diameter of 6 μm was applied and dried to a thickness of 15 μm to form a negative electrode active material layer. . In this way, a bipolar electrode was formed.

  Moreover, only the same positive electrode material or negative electrode material was apply | coated to the single side | surface to the same collector as the above, and the edge part electrode for arrange | positioning at the both ends of lamination | stacking was formed.

  A battery element having a three-layer structure was formed by sandwiching an electrolyte layer in which a crosslinked gel electrolyte precursor was impregnated with a polyester nonwoven fabric separator having a thickness of 25 μm and a hardness of JIS-A 60 between these electrodes.

  An aluminum tab having a thickness of 100 μm and a width of 100 mm was vibration welded on the positive electrode end side of the battery element, and a copper tab having a thickness of 100 μm and a width of 100 mm was vibration welded on the negative electrode end side. This was sealed with a laminating material and crosslinked by heating at about 80 ° C. for about 2 hours to obtain a bipolar battery having a three-layer structure of Example 7.

  In the following Examples 8 to 16, bipolar batteries were manufactured by the same manufacturing process as in Example 7. In Examples 8 to 16, the number of single cell layers similar to which of the above-described examples is stacked.

(Example 8)
In Example 8, a bipolar battery in which three single battery layers of Example 2 were stacked was produced.

Example 9
In Example 9, a bipolar battery in which three single battery layers of Example 3 were stacked was produced.

(Example 10)
In Example 10, a bipolar battery in which three single battery layers of Example 4 were stacked was manufactured.

(Example 11)
In Example 11, a bipolar battery in which three single battery layers of Example 5 were stacked was produced.

(Example 12)
In Example 12, a bipolar battery in which three single battery layers of Example 6 were stacked was produced.

(Example 13)
In Example 13, a bipolar battery in which 10 single battery layers of Example 4 were stacked was produced.

(Example 14)
In Example 14, a bipolar battery in which 100 single cell layers of Example 4 were stacked was produced.

(Example 15)
In Example 15, a three-layer bipolar battery in which the single battery layer of Example 2 was sandwiched between the single battery layers of Example 3 was produced.

(Example 16)
In Example 16, a three-layer bipolar battery in which the single battery layer of Example 5 was sandwiched between the single battery layers of Example 6 was produced.

(Comparative Example 2)
As Comparative Example 2, a bipolar battery in which three single battery layers of Comparative Example 1 were laminated was produced.

(Comparative Example 3)
As Comparative Example 3, a bipolar battery in which 10 cell layers of Comparative Example 1 were stacked was fabricated.

(Comparative Example 4)
As Comparative Example 4, a bipolar battery in which 100 single battery layers of Comparative Example 1 were stacked was fabricated.

<Test>
For the bipolar batteries of Examples 7 to 16 and Comparative Examples 2 to 4 manufactured as described above, similarly to the first example, “measurement of resonance frequency”, “measurement of vibration damping factor”, “heat rise and heat dissipation” The “time measurement” test was performed. In the measurement of the heat rise, the temperature of the second layer was measured for Examples 7 to 12, 15, 16 and Comparative Example 2, and the fifth layer was measured for Examples 13 and 14 and Comparative Examples 3 and 4. Was measured.

  The test results are summarized in FIG.

<Test results>
FIG. 11 is a diagram showing test results.

  In the test results, reference is made to the first resonance peak. In all of Examples 7 to 16, it was found that the first resonance peak was 100 Hz or higher, and even when mounted on a vehicle, it did not resonate. On the other hand, in all of Comparative Examples 2 to 4, the first resonance peak was 100 Hz or less, and the result of resonance when mounted on a vehicle was obtained. Thus, it was found that a bipolar battery that does not resonate with vehicle vibrations can be obtained by thinning the positive electrode active material layer and the negative electrode active material layer as in the present invention even if the number of single battery layers is increased.

  Refer to the vibration damping rate in the test results. It was found that any of Examples 7 to 16 had a higher vibration damping rate than Comparative Example 1. Further, when Examples 11, 13, and 14 were compared, it was found that the vibration damping rate was higher when the number of layers was larger.

  About Comparative Examples 2-4, even if it increased the number of lamination | stacking, it turned out that a vibration damping factor is hardly different from the comparative example 1. FIG.

  Refer to heat rise in the test results. The heat rise was 22 δT at maximum in Example 9 among Examples 7-16. However, referring to Comparative Examples 2 to 4, it can be seen that the temperatures rose considerably at 40δT, 60δT, and 80δT. This is because in Examples 7 to 16, the positive electrode active material layer and the negative electrode active material layer were thin, and the internal resistance of the whole battery element was smaller than that of Comparative Examples 2 to 4, so the amount of heat generation was small.

  The heat rise of Example 16 was the lowest. This is because the single cell layer of Example 5 is sandwiched between the single cell layers of Example 6 in Example 16. The hardness of the separator of the cell of Example 6 is higher than the hardness of the separator of Example 5. Therefore, since the heat dissipation is improved when the hardness is low, the heat dissipation is improved on the inner side of the stacked layer where heat is accumulated. Therefore, the heat rise was reduced by the amount of heat dissipation promoted inside.

  Comparing Example 15 and Example 16, similarly, the hardness of the separator is different in each cell layer. However, since the thickness of the unit cell layer constituting each of the sixteenth embodiments is smaller, the heat rise in the sixteenth embodiment is smaller.

  Refer to the heat release time in the test results. The heat radiation time was 60 minutes or longer in Comparative Examples 2 to 4, whereas in Examples 7 to 16, it was 18 minutes at the maximum. From this result, it can be seen that, as in Examples 7 to 16, the heat dissipation characteristics are remarkably improved by reducing the thickness of the positive electrode active material layer and the negative electrode active material layer as compared with the conventional structure.

  Regarding the heat dissipation time, Example 16 was the shortest. This is because the heat dissipation is high for the same reason that the heat rise is low.

  As described above, it can be seen that all of Examples 7 to 16 are improved in vibration characteristics and temperature characteristics as compared with Comparative Examples 2 to 4 of the conventional structure.

(Second Embodiment)
In the second embodiment, a plurality of bipolar batteries of the first embodiment are connected in parallel and / or in series to constitute an assembled battery.

  12 is a plan view of the bipolar battery, FIG. 13 is a three-sided view showing the bipolar battery stored in the case, and FIG. 14 is a three-sided view showing the assembled battery.

  As shown in FIG. 12, when the bipolar battery 10 is viewed from the planar direction, the positive electrode tab 30a and the negative electrode tab 30b are drawn out on both sides. For example, as shown in FIG. 13, four such bipolar batteries 10 are stored in the case 60 in a stacked manner. In FIG. 13, the positive electrode tabs 30 a and the negative electrode tabs 30 b are arranged on the same side, and are connected to each other by a positive electrode terminal 61 and a negative electrode terminal 62.

  A battery case 60 in which the bipolar battery 10 is stored is laminated and integrated by a connecting plate 71 and a fixing screw 72 to form an assembled battery 70 as shown in FIG. In the assembled battery 70, the positive terminals 61 and the negative terminals 62 of the battery cases 60 are connected to each other by plate-like bus bars 73 and 74.

  Thus, the assembled battery 70 in which a plurality of bipolar batteries are connected in parallel is formed.

  In this assembled battery 70, ultrasonic welding, heat welding, laser welding, rivet, caulking, electron beam, or the like can be used as a connection method when a plurality of bipolar batteries 10 are connected. By adopting such a connection method, it is possible to manufacture the assembled battery 70 having long-term reliability.

  According to the assembled battery 70, by using the bipolar battery 10 according to the first embodiment described above to form an assembled battery, high capacity and high output can be obtained, and the reliability of each battery is high. Long-term reliability as an assembled battery can be improved.

  In addition, by using the case for connecting a small number of bipolar batteries 10 as described above, it is possible to configure assembled batteries with various designs without manufacturing many assembled battery types, thereby reducing manufacturing costs.

  In addition, the connection of the bipolar battery 10 as an assembled battery is not restricted to a parallel connection as mentioned above. A plurality of them may be connected in series, and a series connection and a parallel connection may be combined.

(Third embodiment)
In the third embodiment, the bipolar battery 10 of the first embodiment or the assembled battery 70 of the second embodiment is mounted as a driving power source to constitute a vehicle. As a vehicle using the bipolar battery 10 or the assembled battery 70 as a motor power source, there is an automobile whose wheels are driven by a motor, such as an electric vehicle and a hybrid vehicle.

  For reference, FIG. 15 shows a schematic diagram of an automobile 80 on which the assembled battery 70 is mounted. The assembled battery 70 mounted on the automobile has the characteristics described above. For this reason, an automobile equipped with the assembled battery 70 has high durability and can provide sufficient output even after being used for a long period of time.

It is sectional drawing which shows the structure of the battery element for bipolar batteries. It is a figure which shows a battery element. It is the figure which compared the single battery layer of this invention, and the conventional single battery layer. It is the figure which made the battery element a mass spring model. It is the figure which made the battery element a mass spring model. It is a figure which shows the relationship between time and temperature when it supplies with electricity to a battery element. It is a figure which shows the relationship between the frequency of the vibration added to the battery element, and a vibration transmissibility. It is a figure which shows the specification of the bipolar battery of Examples 1-6. It is a figure which shows the specification of the bipolar battery of Examples 1-6. It is a figure which shows a test result. It is a figure which shows a test result. It is a top view of a bipolar battery. It is a trihedral view showing the bipolar battery stored in the case. It is a three-plane figure which shows an assembled battery. The schematic of the motor vehicle carrying an assembled battery is shown.

Explanation of symbols

10 ... Bipolar battery,
12 ... positive electrode active material layer,
13 ... negative electrode active material layer,
14, 51, 52 ... separator,
15 ... single cell layer,
16: Bipolar electrode,
17 ... End current collector,
18 ... seal member,
20 ... Battery element,
30a ... positive electrode tab,
30b ... negative electrode tab,
31 ... trout,
32, 53, 54 ... springs,
33, 55, 56 ... Damper,
40 ... exterior,
41 ... Laminate sheet,
50 ... Battery element,
60 ... Battery case,
61 ... positive terminal,
62 ... negative terminal,
70 ... assembled battery,
71 ... connecting plate,
73 ... Bus bar,
80 ... A car.

Claims (15)

A bipolar electrode in which a positive electrode active material layer is formed on one surface of a current collector and a negative electrode active material layer is formed on the other surface;
Separators alternately stacked with the bipolar electrodes and holding the electrolyte;
Have
In the unit cell layer including the adjacent positive electrode active material layer, the separator, and the negative electrode active material layer, at least one of the positive electrode active material layer and the negative electrode active material layer is thicker than the separator. Bipolar battery characterized by being thin.   2. The bipolar battery according to claim 1, wherein the thickness of at least one of the positive electrode active material layer and the negative electrode active material layer is 0.5 to 1.0 times the thickness of the separator.   The bipolar battery according to claim 1 or 2, wherein a thickness of the single cell layer is 100 µm or less.   The bipolar battery according to claim 1, wherein the separator has a thickness of 20 μm or less.   The bipolar battery according to any one of claims 1 to 4, wherein the separator has a hardness of JIS-A20 to 110.   The bipolar battery according to claim 1, wherein an average particle diameter of the positive electrode active material constituting the positive electrode active material layer is 2 μm or less.   The bipolar battery according to claim 1, wherein an average particle diameter of the negative electrode active material constituting the negative electrode active material layer is 2 μm or less.   The bipolar battery according to any one of claims 1 to 7, wherein the separator is selected from the group consisting of a polyester resin, an aramid resin, and a polyolefin resin, alone or in combination.   The bipolar battery according to claim 1, wherein the single cell layer has a thickness of 50 μm or less.   The bipolar battery according to any one of claims 1 to 9, wherein the hardness of the separator is not uniform for each unit cell layer.   The bipolar battery according to claim 10, wherein the separator disposed outside the stack has a higher hardness than the separator disposed inside the stack. For the positive electrode active material layer, a Li · Mn-based composite oxide is used,
The bipolar battery according to any one of claims 1 to 11, wherein a crystalline carbon material or an amorphous carbon material is used for the negative electrode active material layer.   The bipolar battery according to claim 1, wherein at least two single cell layers are formed.   An assembled battery formed by connecting a plurality of the bipolar batteries according to claim 1.   A vehicle comprising the bipolar battery according to claim 1 or the assembled battery according to claim 14 as a driving power source.

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