JP4096718B2 - Bipolar battery, bipolar battery manufacturing method, battery pack and vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bipolar battery, and more particularly to a bipolar battery using a polymer gel electrolyte as an electrolyte, a method for manufacturing the bipolar battery, a battery pack, and a vehicle equipped with the bipolar battery.
[0002]
[Prior art]
Lithium secondary batteries include those using a solid electrolyte, those using a liquid electrolyte, and those using a polymer gel electrolyte as the electrolyte enclosed therein.
[0003]
For the solid electrolyte, for example, an all solid polymer electrolyte such as polyethylene oxide is used, while for the liquid electrolyte, a 100% electrolytic solution is used. The polymer gel electrolyte should be said to be an intermediate between them. For example, polyvinylidene fluoride (PVDF) itself has an electrolyte solution held in a polymer skeleton having no lithium ion conductivity ( For example, see Patent Document 1.)
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-204136
[Problems to be solved by the invention]
When a single cell layer is formed using this polymer gel electrolyte and a bipolar battery is manufactured by laminating a plurality of the single cell layers, the electrolyte oozes out between each single cell layer and contacts the electrolyte of other single cell layers. As a result, there is a problem that a short circuit between the cell layers called liquid junction occurs.
[0006]
Therefore, an object of the present invention is to provide a bipolar battery in which a liquid junction between the single battery layers is prevented even when a battery is configured by laminating a plurality of single battery layers using a polymer gel electrolyte.
[0007]
[Means for Solving the Problems]
In the first aspect of the present invention, 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 is laminated with a gel electrolyte layer interposed therebetween. A battery having a double-sided pressure-sensitive adhesive member disposed so as to surround a single cell layer including the adjacent positive electrode active material layer, the gel electrolyte layer, and the negative electrode active material layer; The double-sided pressure-sensitive adhesive member comprises an insulating material serving as a base material and a pressure-sensitive adhesive provided on both surfaces of the insulating material, and is sandwiched between two current collectors together with the single cell layer by the pressure-sensitive adhesive. This is a bipolar battery bonded between two current collectors.
[0008]
In the second aspect of the present invention, at least one of a positive electrode active material layer, a gel electrolyte layer, and a negative electrode active material layer is laminated at the center of the current collector, and further, a substrate and the substrate are formed on the edge of the current collector. Bipolar that creates a plurality of single cells formed by laminating double-sided pressure-sensitive adhesive members each having a pressure-sensitive adhesive provided on both sides of the material, laminates the single cells, and bonds the single cells to each other with the pressure-sensitive adhesive of the double-sided pressure-sensitive adhesive member It is a manufacturing method of a battery.
[0009]
【The invention's effect】
According to the first bipolar battery of the present invention, the double-sided pressure-sensitive adhesive member disposed so as to surround the single cell layer is bonded between the two current collectors, thereby serving as a seal layer. Therefore, it is possible to prevent short circuit due to leakage of the gel electrolyte, to prevent moisture and the like from entering from the outside, and to improve the strength of the bipolar battery itself.
[0010]
According to the second method for manufacturing a bipolar battery of the present invention, single cells are prepared first, and then the single cells are stacked and bonded. Therefore, the number of bipolar batteries stacked is taken into account when manufacturing the single cells. It is sufficient to manufacture a large number of the cells without any problem and prepare single cells necessary for manufacturing individual bipolar batteries. Therefore, since it can be divided into two stages, that is, the production of a single cell and the production of a bipolar battery, it is possible to flexibly cope with a change in the number of stacks due to a design change, and in addition, the working time can be shortened. .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
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.
[0012]
(First embodiment)
In the first aspect of the present invention, 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 is laminated with a gel electrolyte layer interposed therebetween. A battery having a double-sided pressure-sensitive adhesive member disposed so as to surround a single cell layer including the adjacent positive electrode active material layer, the gel electrolyte layer, and the negative electrode active material layer; The double-sided pressure-sensitive adhesive member comprises an insulating material serving as a base material and a pressure-sensitive adhesive provided on both surfaces of the insulating material, and is sandwiched between two current collectors together with the single cell layer by the pressure-sensitive adhesive. This is a bipolar battery bonded between two current collectors.
[0013]
In the second aspect of the present invention, at least one of a positive electrode active material layer, a gel electrolyte layer, and a negative electrode active material layer is laminated at the center of the current collector, and further, a substrate and A plurality of single cells formed by laminating double-sided pressure-sensitive adhesive members each having a pressure-sensitive adhesive provided on both surfaces of the base material are laminated, and the single cells are laminated, and the single cells are bonded together by the pressure-sensitive adhesive of the double-sided pressure-sensitive adhesive member. A method for manufacturing a bipolar battery.
[0014]
FIG. 1 is a cross-sectional view for explaining the structure of a bipolar battery to which the present invention is applied, and FIG. 2 is a partially enlarged cross-sectional view of a unit cell constituting the bipolar battery.
[0015]
In the bipolar battery 1, a positive electrode active material layer 3 and a negative electrode active material layer 4 are formed in the center of both surfaces of one current collector 2 other than both ends. The positive electrode active material layer 3 and the negative electrode active material 4 of the current collector 2 are formed. A single battery layer 6 is formed with an electrolyte layer 5 sandwiched between the material layer 4 and a plurality of single battery layers 6 are stacked. A current collector (referred to as an end current collector 7) at both ends is connected to the electrodes of the entire bipolar battery.
[0016]
And the structure which provided the positive electrode active material layer 3 and the negative electrode active material layer 4 on both sides of the electrical power collector 2 is called a bipolar electrode.
[0017]
Here, the electrolyte layer 5 is, for example, a gel electrolyte in which about several to 98% by weight of an electrolytic solution is held in a polymer skeleton, and in this embodiment, in particular, 70% by weight or more of the electrolytic solution is held. A gel electrolyte can be used.
[0018]
In this bipolar battery 1, in order to prevent liquid leakage from the unit cell layer 6, the periphery of each unit cell layer 6 is surrounded, and between the current collectors 2, or between the current collectors 2 and the end current collectors 7. A double-sided adhesive member 9 is provided between the two.
[0019]
The double-sided pressure-sensitive adhesive member 9 is a double-sided tape comprising a base material 10 and a pressure-sensitive adhesive 11 provided on both surfaces of the base material 10. The base material 10 is made of an insulating resin such as polypropylene (PP), polyethylene (PE), or polyamide synthetic fiber. The pressure-sensitive adhesive 11 is made of a solvent-resistant material such as synthetic rubber, butyl rubber, synthetic resin, or acrylic. By using such a material for the double-sided pressure-sensitive adhesive member 9, it is possible to prevent liquid leakage from the single cell layer 6, and it is possible to prevent a short circuit due to contact between the current collectors.
[0020]
Next, the manufacturing procedure of the bipolar battery 1 of the present invention will be described.
[0021]
3-7 is a figure for demonstrating the manufacturing procedure of the bipolar battery of this invention.
[0022]
3 is a view showing a state where a gel electrolyte layer and a double-sided pressure-sensitive adhesive member are laminated on a current collector, FIG. 4 is a view showing a state where a double-sided pressure-sensitive adhesive member is laminated, and FIG. 5 is an AA of the laminate shown in FIG. FIG. 6 is a cross-sectional view, FIG. 6 is a plan view showing how single cells are stacked, and FIG. 7 is a side view showing how single cells are stacked.
[0023]
As a manufacturing procedure of the bipolar battery 1 of the present invention, as shown in FIG. 3, first, an electrode layer (positive electrode active material layer 3 or negative electrode active material layer 4, for example, positive electrode active material layer) is formed on the end current collector 7. 3) is laminated, and a gel electrolyte layer 5 is further laminated thereon. Then, the double-sided pressure-sensitive adhesive member 9 is disposed on the edge of the end current collector 7. Here, the double-sided pressure-sensitive adhesive member 9 has a through-hole formed at the center so as to cover only the edge of the end current collector 7.
[0024]
When the double-sided pressure-sensitive adhesive member 9 is thus laminated, the double-sided pressure-sensitive adhesive member 9 is disposed so as to surround the gel electrolyte layer 5 as shown in FIG. Here, since the double-sided pressure-sensitive adhesive member 9 is provided with the pressure-sensitive adhesive 11 on both sides, the double-sided pressure-sensitive adhesive member 9 is bonded at the moment when it is laminated on the current collector 7.
[0025]
In addition, the thickness of the double-sided adhesive member 9 is thicker than the thickness of the positive electrode active material layer 3 and the gel electrolyte layer 5, as shown in FIG. The thickness of the double-sided pressure-sensitive adhesive member 9 is within ± 30 μm of the total thickness of the positive electrode active material layer 3, the gel electrolyte layer 5, and the negative electrode active material layer 4 to be laminated later, that is, the thickness of the unit cell layer 6. It is desirable that By matching the thickness of the double-sided pressure-sensitive adhesive member 9 with the total thickness of the unit cell layer 6, it is possible to prevent the current collectors 2 and 7 from being distorted due to an increase in the number of layers, and to prevent a decrease in reactivity and short circuit due to the distortion. be able to. The width of the double-sided pressure-sensitive adhesive member 9 is desirably about 5 mm in order to reduce the size of the bipolar battery 1.
[0026]
The end current collector 7, the positive electrode active material layer 3, the gel electrolyte layer 5, and the double-sided pressure-sensitive adhesive member 9 stacked as described above are referred to as a single cell 12. The single cell 13 located in the middle part of the bipolar battery 1 is provided with electrode layers on both sides of the current collector 2, for example, a positive electrode active material layer 3 on the upper surface and a negative electrode active material layer 4 on the lower surface. Say. That is, a gel electrolyte layer 5 is laminated on a bipolar electrode formed by laminating a negative electrode active material layer 4, a current collector 2, and a positive electrode active material layer 3, and a double-sided adhesive member 9 is laminated on the edge of the current collector 2. Is a single cell 13. By increasing the number of stacked single cells 13, the bipolar battery 1 can have a desired number of stacked layers.
[0027]
The single cell 14 stacked at the end of the bipolar battery 1 is different from the single cell 12 stacked at the beginning described above in that the end current collector 7 is stacked on the negative electrode active material layer 4.
[0028]
In this way, a plurality of single cells are manufactured in advance with the single cells 12 to 14 as one unit, and the bipolar battery 1 is stacked in a necessary number. A state of stacking the single cells 12 to 14 will be described.
[0029]
As shown in FIGS. 6 and 7, the middle unit cell 13 is stacked on the first unit cell 12. By repeating this, the number of stacked single cells 13 on the single cell 12 increases. When the single cell 13 is laminated on the single cell 12, the adhesive 11 of the double-sided pressure-sensitive adhesive member 9 of the single cell 12 is bonded to the lower surface of the current collector 2 of the single cell 13. Similarly, when another unit cell 13 is laminated on the unit cell 13, the adhesive 11 of the lower unit cell 13 is adhered to the lower surface of the current collector 2 of the upper unit cell 13. Thus, the double-sided pressure-sensitive adhesive member 9 is bonded to the current collector 2 every time the single cells 13 are stacked, and seals the gel electrolyte layer 5. Thereby, the liquid leakage from the gel electrolyte layer 5 can be prevented.
[0030]
Finally, as shown in FIG. 7, the single cell 14 is laminated, and the current collector 7 of the single cell 14 is bonded to the double-sided adhesive member 9 of the single cell 13, thereby completing the bipolar battery 1.
[0031]
As described above, in the bipolar battery 1 of the present invention, the double-sided pressure-sensitive adhesive member 9 is disposed between the current collectors so as to surround the single-cell layer 6 together with the single-cell layer 6. Is adhered between the two current collectors to serve as a sealing layer, and liquid leakage from the gel electrolyte layer 5 of the single battery layer 6 can be prevented. Accordingly, liquid junction due to liquid leakage can be prevented. In addition, the double-sided adhesive member 9 can prevent the entry of moisture and the like from the outside, and the strength of the bipolar battery itself can be improved.
[0032]
Further, even when the ratio of the electrolytic solution contained in the gel electrolyte layer 5 is 70% by weight or more and the liquefaction of the gel electrolyte layer 5 is liable to occur, the liquid junction is prevented because there is no liquid leakage.
[0033]
Furthermore, since the bipolar battery 1 of the present invention is formed by stacking the single cells 12 to 14, when the single cell is manufactured, it is manufactured in large quantities without considering the number of stacked bipolar batteries 1, and individual bipolar batteries It suffices to prepare the single cells 12 to 14 necessary for manufacturing one. Therefore, since it can be divided into two stages, that is, the production of a single cell and the production of the bipolar battery 1, it is possible to flexibly cope with a change in the number of stacks due to a design change, and in addition, the work time can be shortened. it can.
[0034]
Regarding the bipolar battery 1, members constituting the battery other than the double-sided adhesive member 9 may be the same as those used in a general lithium ion secondary battery.
[0035]
The current collector, positive electrode, negative electrode, gel electrolyte, etc. that can be used for the bipolar battery 1 will be described below.
[0036]
[Current collector]
The current collector needs to be formed by laminating and stacking whatever shape it has, such as aluminum, copper, titanium, nickel, stainless steel (for example, by a thin film manufacturing technique such as spray coating). SUS), a metal powder such as an alloy thereof as a main component, and a current collector metal paste containing a binder (resin) and a solvent is heated and molded, and is formed by the metal powder and the binder. It will be. In addition, these metal powders may be used alone or in combination of two or more, and moreover, different types of metal powders are laminated in multiple layers taking advantage of the characteristics of the manufacturing method. It may be a thing.
[0037]
The binder is not particularly limited. For example, a conventionally known resin binder material such as an epoxy resin can be used, and a conductive polymer material may be used.
[0038]
Although the thickness of a collector is not specifically limited, Usually, it is about 1-100 micrometers.
[0039]
[Positive electrode active material layer]
The positive electrode includes a positive electrode active material. In addition to this, an electrolyte, a lithium salt, or the like may be included in order to increase ion conductivity. Moreover, in order to improve electronic conductivity, a conductive support agent, NMP (N-methyl-2-pyrrolidone) as a solvent for adjusting slurry viscosity, AIBN (azobisisobutyronitrile) as a polymerization initiator, and the like may be included. In particular, it is desirable that at least one of the positive electrode and the negative electrode contains an electrolyte, preferably a solid polymer electrolyte. However, in order to further improve the battery characteristics of the bipolar battery, it is preferable to contain them in both.
[0040]
As the positive electrode active material, a composite oxide of transition metal and lithium, which is also used in a solution-type lithium ion battery, can be used. Specifically, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, Li · Mn-based composite oxide such as spinel LiMn ₂ O _4, Li · such LiFeO ₂ Examples thereof include Fe-based composite oxides. In addition, transition metal and lithium phosphate compounds and sulfuric acid compounds such as LiFePO ₄ ; transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ ; PbO ₂ , AgO, NiOOH etc. are mentioned.
[0041]
The positive electrode active material may have any particle diameter as long as the positive electrode material can be formed into a paste by spray coating or the like. Further, in order to reduce the electrode resistance of the bipolar battery, it is preferable to use a battery whose electrolyte is smaller than a particle diameter generally used in a solution type lithium ion battery which is not solid. Specifically, the average particle diameter of the positive electrode active material is preferably 10 to 0.1 μm.
[0042]
As the electrolyte contained in the positive electrode, a solid polymer electrolyte, a polymer gel electrolyte, a laminate of these, and the like can be used. That is, the positive electrode can have a multi-layer structure, and on the collector side and the electrolyte side, a layer in which the type of electrolyte constituting the positive electrode, the type and particle size of the active material, and the mixing ratio thereof are changed is formed. You can also.
[0043]
The polymer gel electrolyte is a solid polymer electrolyte having ion conductivity containing an electrolyte solution usually used in a lithium ion battery. Further, in the polymer skeleton having no lithium ion conductivity, In addition, those holding the same electrolytic solution are also included.
[0044]
Here, as the electrolyte solution (electrolyte salt and plasticizer) contained in the polymer gel electrolyte, any electrolyte solution that is usually used in a lithium ion battery may be used. For example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , inorganic acid anion salts such as LiAlCl ₄ and Li ₂ B ₁₀ Cl ₁₀ , organic acid anions such as LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N Including at least one lithium salt (electrolyte salt) selected from ionic salts, cyclic carbonates such as propylene carbonate and ethylene carbonate; chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane Ethers such as 1,2-dibutoxyethane; lactones such as γ-butyrolactone; nitriles such as acetonitrile; esters such as methyl propionate; amides such as dimethylformamide; methyl acetate and methyl formate The thing using organic solvents (plasticizer), such as an aprotic solvent, which mixed 1 type or 2 types or more from at least chosen can be used. However, it is not necessarily limited to these.
[0045]
For example, polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), etc. are used as the polymer having no lithium ion conductivity used in the polymer gel electrolyte. it can. However, it is not necessarily limited to these. Note that PAN, PMMA, etc. are in a class that has almost no ionic conductivity, and thus can be a polymer having the above ionic conductivity, but here, they are used for a polymer gel electrolyte. This is exemplified as a polymer having no lithium ion conductivity.
[0046]
As the lithium salt, for _{example, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 Cl 10 and the like inorganic acid anion _{salts, Li (CF 3 SO 2)} 2 N, An organic acid anion salt such as Li (C ₂ F ₅ SO ₂ ) ₂ N or a mixture thereof can be used. However, it is not necessarily limited to these.
[0047]
Examples of the conductive assistant include acetylene black, carbon black, and graphite. However, it is not necessarily limited to these.
[0048]
The amount of the positive electrode active material, electrolyte (preferably solid polymer electrolyte), lithium salt, and conductive additive in the positive electrode is determined in consideration of the intended use of the battery (output priority, energy priority, etc.) and ion conductivity. Should. For example, if the amount of the electrolyte in the positive electrode, particularly the solid polymer electrolyte, is too small, the ionic conduction resistance and the ionic diffusion resistance in the active material layer will increase, and the battery performance will deteriorate. On the other hand, when the amount of the electrolyte in the positive electrode, particularly the solid polymer electrolyte, is too large, the energy density of the battery decreases. Therefore, in consideration of these factors, the solid polymer electrolysis mass suitable for the purpose is determined.
[0049]
The thickness of the positive electrode is not particularly limited, and should be determined in consideration of the intended use of the battery (emphasis on output, emphasis on energy, etc.) and ion conductivity, as described for the blending amount. A typical positive electrode active material layer has a thickness of about 10 to 500 μm.
[0050]
[Negative electrode active material layer]
The negative electrode includes a negative electrode active material. In addition to this, an electrolyte, a lithium salt, a conductive auxiliary agent, and the like may be included to enhance ion conductivity. 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 layer”, and thus the description thereof is omitted here.
[0051]
As the negative electrode active material, a negative electrode active material that is also used in a solution-type lithium ion battery can be used. For example, metal oxide, lithium-metal composite oxide metal, carbon and the like are preferable. More preferred are carbon, transition metal oxide, and lithium-transition metal composite oxide. More preferred are titanium oxide, lithium-titanium composite oxide, and carbon. These may be used alone or in combination of two or more.
[0052]
[Electrolytes]
The electrolyte is a polymer gel electrolyte. This electrolyte can also have a multilayer structure, and a layer in which the type of electrolyte and the component blending ratio are changed can be formed on the positive electrode side and the negative electrode side. When the polymer gel electrolyte is used, the ratio (mass ratio) between the polymer constituting the polymer gel electrolyte and the electrolytic solution is 20:80 to 2:98, which is a range in which the ratio of the electrolytic solution is relatively large.
[0053]
As such a polymer gel electrolyte, a solid polymer electrolyte having ion conductivity includes an electrolytic solution usually used in a lithium ion battery. Those in which the same electrolyte solution is held in the molecular skeleton are also included. Since these are the same as the polymer gel electrolyte described as one of the electrolytes included in the [positive electrode], description thereof is omitted here.
[0054]
These solid polymer electrolytes or polymer gel electrolytes can be included in the positive electrode and / or the negative electrode as described above in addition to the polymer electrolyte constituting the battery, but depending on the polymer electrolyte, positive electrode, and negative electrode constituting the battery. Different polymer electrolytes may be used, the same polymer electrolyte may be used, or different polymer electrolytes may be used depending on the layer.
[0055]
The thickness of the electrolyte constituting the battery is not particularly limited. However, in order to obtain a compact bipolar battery, it is preferable to make it as thin as possible as long as the function as an electrolyte can be secured. The thickness of a general solid polymer electrolyte layer is about 10 to 100 μm. However, the shape of the electrolyte can be easily formed so as to cover the upper surface of the electrode (positive electrode or negative electrode) as well as the outer periphery of the side surface, taking advantage of the characteristics of the manufacturing method. It is not always necessary to have a substantially constant thickness.
[0056]
[Battery exterior material (battery case)]
In order to prevent external impact and environmental degradation, the bipolar battery is a battery that includes the entire battery stack including the template, which is the main body of the bipolar battery, in order to prevent external impact and environmental degradation during use. It may be housed in an exterior material or a battery case (not shown).
[0057]
From the viewpoint of weight reduction, conventionally known battery exteriors such as polymer-metal composite laminate films and aluminum laminate packs in which metals (including alloys) such as aluminum, stainless steel, nickel, and copper are coated with an insulator such as polypropylene film It is preferable that the battery stack is housed and sealed by joining a part or the whole of the peripheral part by heat fusion using a material.
[0058]
In this case, the positive electrode and the negative electrode lead may be structured to be sandwiched between the heat-sealed portions and exposed to the outside of the battery exterior material. In addition, the use of polymer-metal composite laminate films and aluminum laminate packs with excellent thermal conductivity allows heat to be efficiently transferred from the heat source of the automobile and the inside of the battery to be quickly heated to the battery operating temperature. preferable.
[0059]
[Positive electrode and negative electrode terminal plate]
The positive electrode and the negative electrode terminal plate have functions as terminals and are preferably as thin as possible from the viewpoint of thinning, but the electrodes, electrolytes, and current collectors that are laminated by film formation have low mechanical strength. For this reason, it is desirable to have sufficient strength to sandwich and support them from both sides. Furthermore, it can be said that the thickness of the positive electrode and the negative electrode terminal plate is usually preferably about 0.1 to 2 mm from the viewpoint of suppressing the internal resistance at the terminal portion.
[0060]
As the material of the positive electrode and the negative electrode terminal plate, materials usually used in lithium ion batteries can be used. For example, aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof can be used. Aluminum is preferably used from the viewpoints of corrosion resistance, ease of production, economy, and the like.
[0061]
The material of the positive electrode terminal plate and the negative electrode terminal plate may be the same material or different materials. Furthermore, the positive electrode and the negative electrode terminal plate may be a laminate of different materials.
[0062]
The shape of the positive electrode and the negative electrode terminal plate is a shape obtained by tracing the outer surface of a heat source of an automobile when used also as a template, and the terminal plate is installed in a terminal plate provided at a position opposite to the template. Any shape that traces the outer surface of the current collector may be used, and it may be formed by tracing by press molding or the like. Note that the terminal plate provided at a position opposite to the template may be formed by spray coating in the same manner as the current collector.
[0063]
[Positive electrode and negative electrode lead]
As for the positive electrode and the negative electrode lead, known leads usually used in lithium ion batteries can be used. In addition, since the part taken out from the battery exterior material (battery case) does not have a distance from the heat source of the automobile, it does not affect the automobile parts (particularly electronic equipment) by contacting with them and causing electric leakage. In addition, it is preferable to coat with a heat-resistant insulating heat-shrinkable tube or the like.
[0064]
FIG. 8 is a diagram showing an external appearance when the bipolar battery 1 shown in FIGS. 1 and 2 is configured as a battery 20 using an aluminum laminate pack. In this battery 20, the positive electrode and negative electrode terminal plates are provided on the end current collector 7 of the bipolar battery 1, and leads are further attached to form electrodes 23 and 24.
[0065]
Next, an experimental example in which the bipolar battery 1 is actually manufactured and evaluated will be described.
[0066]
Experimental example <liquid junction evaluation>
The bipolar battery 1 was manufactured in the same manner as in the above-described embodiment, and the liquid junction between the single cells was evaluated.
[0067]
(Sample preparation)
The bipolar battery 1 actually manufactured as an example is as follows.
[0068]
The current collector 2 uses a 20 μm stainless steel (SUS) foil, the end current collector 7 is formed with the positive electrode active material layer 3 or the negative electrode active material layer 4, and the current collector 2 has the positive electrode active material layer 3 and the negative electrode active material layer 4 were formed.
[0069]
The positive electrode active material layer 3 is prepared by mixing LiMn ₂ O ₄ with acetylene black as a conductive additive, polyvinylidene fluoride (PVDF) as a binder, and N-methyl-2-pyrrolidone (NMP) as a viscosity adjusting solvent. The positive electrode active material is prepared as a positive electrode active material, applied to one surface of a stainless steel foil (thickness 20 μm) as a current collector, and dried to form a positive electrode active material layer 3 having a thickness of 40 μm.
[0070]
The negative electrode active material layer 4 was prepared by mixing Li ₄ Ti ₅ O ₁₂ with acetylene black as a conductive additive, PVDF as a binder, NMP as a viscosity adjusting solvent, and preparing a negative electrode slurry. Is applied to the opposite surface of the coated stainless steel foil and dried to form a negative electrode active material layer 4 having a thickness of 50 μm.
[0071]
The polymer gel electrolyte layer 5 is made of 100 μm thick polypropylene (PP) unknown cloth, 5% by weight of a polymer (copolymer of polyethylene oxide and polypropylene oxide), and a mixing ratio of 1: 3 ethylene carbonate (EC) + dimethyl. A gel electrolyte composed of 95% by weight of carbonate (DMC) and 1.0 mol / l of Li (C ₂ F ₅ SO ₂ ) ₂ N with respect to the EC + DMC electrolytic solution is held.
[0072]
The double-sided pressure-sensitive adhesive member 9 was prepared using polypropylene (PP) for the base material 10 and synthetic rubber for the pressure-sensitive adhesive 11 and having a width of 5 mm and a thickness of 190 μm.
[0073]
The number of single battery layers 6 was five, and the single cells were bonded and sealed with the adhesive 11 of the double-sided pressure-sensitive adhesive member 9 when the single cells 12 to 14 were laminated.
[0074]
Further, as a comparative example of this evaluation, a bipolar battery having the same structure without the double-sided adhesive member 9 was formed.
[0075]
The liquid junction was evaluated by performing a charge / discharge cycle test of the bipolar battery 1 of the example and the comparative example. The charging / discharging cycle was performed by charging at a current of 0.5 C, and discharging was performed at a current of 0.5 C, and this was defined as one cycle.
[0076]
(Evaluation results)
In the bipolar battery 1 of the example, no liquid junction (short circuit) occurred between the electrodes even when the charge / discharge cycle exceeded 50 cycles, and the output voltage was maintained.
[0077]
On the other hand, in the bipolar battery 1 of the comparative example, during the first charge, the electrolyte oozes out of the single cell layer and contacts with the electrolyte layer 5 of the other single cell layer, resulting in a liquid junction. The voltage dropped significantly.
[0078]
From this evaluation result, it can be seen that by providing the double-sided pressure-sensitive adhesive member 9 surrounding each unit cell layer 6, a liquid junction between the unit cells can be reliably prevented.
[0079]
<Thickness test of double-sided adhesive member 9>
Next, the test was performed by changing the thickness of the double-sided pressure-sensitive adhesive member 9.
[0080]
(Sample preparation)
The bipolar battery 1 produced as an example has the same structure as the above <liquid junction evaluation>. The thickness of the double-sided pressure-sensitive adhesive member 9 included in the bipolar battery of the example is the thickness of the single battery layer 6, that is, the positive electrode active material layer 3 (40 μm), the gel electrolyte layer 5 (100 μm), and the negative electrode active material layer 4 (50 μm). ) To 190 μm.
[0081]
As comparative examples for evaluation, bipolar batteries differing only in the thickness of the double-sided pressure-sensitive adhesive member 9 were produced. As Comparative Examples 1 to 6, bipolar batteries having a double-sided pressure-sensitive adhesive member 9 with thicknesses of 100 μm, 120 μm, 160 μm, 220 μm, 260 μm, and 300 μm were manufactured in this order.
[0082]
Thickness was evaluated by repeating 10 charge / discharge cycles for the bipolar batteries of Examples and Comparative Examples 1 to 6, respectively, and comparing the discharge capacities at the 10th cycle. The charging / discharging cycle was performed by charging at a current of 0.5 C, and discharging was performed at a current of 0.5 C, and this was defined as one cycle.
[0083]
(Evaluation results)
FIG. 9 is a diagram showing an evaluation result of the discharge capacity with respect to the thickness of the double-sided pressure-sensitive adhesive member. FIG. 9 shows the discharge capacity of the comparative example, assuming that the discharge capacity at the 10th cycle of the bipolar battery (thickness 190 μm) of the example is 100%. As shown in FIG. 9, in Comparative Examples 3 and 4, the discharge capacity was relatively large, and in Comparative Examples 1, 2, 5, and 6, the discharge capacity was significantly reduced.
[0084]
From this evaluation result, the closer the thickness of the double-sided pressure-sensitive adhesive member 9 is to the thickness of the single cell layer 6, the better the discharge capacity, and the thickness of the double-sided pressure-sensitive adhesive member 9 with respect to the thickness of the single cell layer has an error of about 30 μm. It can be seen that the battery performance can be maintained.
[0085]
(Second Embodiment)
A third aspect of the present invention is an assembled battery formed by connecting a plurality of the bipolar batteries 1 of the first embodiment in parallel and / or in series.
[0086]
FIG. 10 is a perspective view of the assembled battery according to the second embodiment, and FIG. 11 is a view of the internal configuration as viewed from above.
[0087]
As shown in FIG. 10 and FIG. 11, the assembled battery 50 includes a battery 20 (see FIG. 8) in which the bipolar battery 1 according to the first embodiment described above is packaged by a laminate pack, and a plurality of directly connected batteries 20 are further connected in parallel. Connected. Between the batteries 20, the electrodes 23 and 24 of each battery are connected by a conductive bar 53. The assembled battery 50 is provided with electrode terminals 51 and 52 on one side of the assembled battery 50 as electrodes of the assembled battery 50.
[0088]
In this assembled battery, ultrasonic welding, thermal welding, laser welding, rivet, caulking, electron beam, etc. can be used as a connection method when the batteries 20 are directly connected and connected in parallel. By adopting such a connection method, a long-term reliable assembled battery can be manufactured.
[0089]
According to the assembled battery according to the second embodiment, by using the battery according to the first embodiment described above, it is possible to obtain a high capacity and a high output by using the battery according to the first embodiment. Since reliability is high, long-term reliability as an assembled battery can be improved.
[0090]
In addition, connection of the battery 20 as an assembled battery may connect all the batteries 20 in parallel, and may connect all the batteries 20 in series.
[0091]
(Third embodiment)
A fourth aspect of the present invention is a vehicle on which the bipolar battery 1 of the first embodiment or the assembled battery 50 of the second embodiment is mounted as a driving power source. A vehicle using the bipolar battery 1 or the assembled battery 50 as a power source for a motor is an automobile in which wheels are driven by a motor, such as an electric vehicle and a hybrid vehicle.
[0092]
For reference, FIG. 12 shows a schematic diagram of an automobile 100 on which the assembled battery 50 is mounted. The assembled battery 50 mounted on the automobile has the characteristics described above. For this reason, an automobile equipped with the assembled battery 50 has high durability and can provide sufficient output even after being used for a long period of time.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining the structure of a bipolar battery to which the present invention is applied.
FIG. 2 is a partial enlarged cross-sectional view of a unit cell constituting the bipolar battery.
FIG. 3 is a view showing a state in which a gel electrolyte layer and a double-sided pressure-sensitive adhesive member are laminated on a current collector.
4 is a view showing a state in which double-sided pressure-sensitive adhesive members are laminated, and FIG. 5 is a partial cross-sectional view of the laminate shown in FIG.
5 is a cross-sectional view of the laminate shown in FIG. 4 taken along the line AA.
FIG. 6 is a plan view showing a state in which single cells are stacked.
FIG. 7 is a side view showing a state in which single cells are stacked.
FIG. 8 is a perspective view showing an external appearance of a battery in which a bipolar battery is made into a laminate pack.
FIG. 9 is a diagram showing an evaluation result of the discharge capacity with respect to the thickness of the double-sided pressure-sensitive adhesive member.
FIG. 10 is a perspective view of an assembled battery.
FIG. 11 is a view of the internal configuration of the assembled battery as viewed from above.
FIG. 12 is a schematic view of an automobile equipped with an assembled battery.
[Explanation of symbols],
1 ... Bipolar battery,
2 ... current collector,
3 ... positive electrode active material layer,
4 ... negative electrode active material layer,
5 ... Gel electrolyte layer,
6 ... cell layer,
7 ... End current collector,
9: Double-sided adhesive member,
10 ... base material,
11 ... Adhesive,
12-14 ... single cell,
50 ... assembled battery,
100 ... an automobile.

Claims (7)

A bipolar battery 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 is a bipolar battery formed by laminating a gel electrolyte layer,
A double-sided pressure-sensitive adhesive member disposed so as to surround the periphery of a unit cell layer including the adjacent positive electrode active material layer, the gel electrolyte layer, and the negative electrode active material layer;
The double-sided adhesive member comprises an insulating material serving as a base material and an adhesive provided on both sides of the insulating material, and is sandwiched between two current collectors together with the single cell layer by the adhesive. A bipolar battery bonded to the two current collectors. 2. The total thickness of the insulating material and the pressure-sensitive adhesive sandwiched between two current collectors is an error of 30 μm with respect to the total thickness of the single cell layer sandwiched between the two current collectors. Bipolar battery. The double-sided adhesive member is
For the base material, a resin selected from the group consisting of polypropylene, polyethylene, and polyamide synthetic fibers is used.
The bipolar battery according to claim 1 or 2, wherein a material having a solvent resistance selected from the group consisting of synthetic rubber, butyl rubber, synthetic resin, and acrylic is used for the adhesive. The positive electrode active material layer includes a composite oxide of lithium and a transition metal,
The bipolar battery according to any one of claims 1 to 3, wherein the negative electrode active material layer includes a composite oxide of carbon or lithium and a transition metal. At least one of a positive electrode active material layer, a gel electrolyte layer, and a negative electrode active material layer is laminated at the center of the current collector, and further, a base material and an adhesive on both surfaces of the base material are provided at the edge of the current collector. Producing a plurality of single cells made by laminating the double-sided adhesive member provided,
A method for manufacturing a bipolar battery, in which the single cells are stacked and the single cells are bonded to each other with the pressure-sensitive adhesive of the double-sided pressure-sensitive adhesive member.   The assembled battery formed by connecting a plurality of the bipolar batteries according to any one of claims 1 to 4 or the bipolar battery manufactured by the manufacturing method according to claim 5 in parallel and / or in series.   The bipolar battery according to any one of claims 1 to 4, the bipolar battery manufactured by the manufacturing method according to claim 5, or the assembled battery according to claim 6 is mounted as a driving power source. vehicle.

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