JP2012248294A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery offering excellent performance.SOLUTION: The battery comprises: a unit cell comprising a positive electrode layer, a negative electrode layer, and an electrolyte layer between the positive electrode layer and the negative electrode layer; and a container receiving the unit cell. The outside of the unit cell in the container is filled with a fluid capable of pressurizing the unit cell, and the unit cell is arranged so that the surface whose normal direction extends from one of the positive electrode layer and the negative electrode layer to the other layer is prevented from contacting with the container.

Description

  The present invention relates to a battery, and more particularly to a battery that pressurizes a unit cell using a fluid.

  A lithium ion secondary battery (hereinafter sometimes referred to as a “lithium secondary battery”) has characteristics that it has a higher energy density than other secondary batteries and can operate at a high voltage. For this reason, it is used as a secondary battery that can be easily reduced in size and weight in information equipment such as a mobile phone, and in recent years, there is an increasing demand for large motive power such as for electric vehicles and hybrid vehicles.

  A lithium ion secondary battery includes a positive electrode layer and a negative electrode layer, and an electrolyte layer disposed therebetween. Examples of the electrolyte used for the electrolyte layer include non-aqueous liquid and solid substances. Are known. When a liquid electrolyte (hereinafter referred to as “electrolytic solution”) is used, the electrolytic solution easily penetrates into the positive electrode layer and the negative electrode layer. Therefore, an interface between the active material contained in the positive electrode layer or the negative electrode layer and the electrolytic solution is easily formed, and the performance is easily improved. However, since the widely used electrolyte is flammable, it is necessary to mount a system for ensuring safety. On the other hand, when a solid electrolyte that is nonflammable (hereinafter referred to as “solid electrolyte”) is used, the above system can be simplified. Therefore, a lithium ion secondary battery (hereinafter referred to as “solid battery”) in a form provided with a layer containing a solid electrolyte that is nonflammable (hereinafter referred to as “solid electrolyte layer”) has been proposed. Yes.

  As a technique related to such a battery, for example, Patent Document 1 discloses an assembled battery in which a plurality of unit cells are combined and accommodated in an assembled battery case. Or the lithium secondary battery which pressurizes a unit cell using the hydrostatic pressure which arises in an assembled battery case by being filled with at least 1 sort (s) of solid powder, or these mixed substances is disclosed.

JP-A-10-214638

  According to the technique disclosed in Patent Document 1, since the unit cell is pressurized using the hydrostatic pressure generated in the assembled battery case, the unit cell is easily pressurized uniformly, and as a result, the performance of the battery is improved. It may be easier. However, when the unit cell is arranged in contact with the assembled battery case, there is hardly any substance that should pressurize the unit cell between the surface of the unit cell in contact with the assembled battery case and the assembled battery case. . Therefore, in the technique disclosed in Patent Document 1, for example, the direction from one layer of the positive electrode layer and the negative electrode layer to the other layer (hereinafter sometimes referred to as “stacking direction”) is normal. When the unit cell is arranged in the assembled battery case so that the surface of the unit cell case is in contact with the assembled battery case, the applied pressure is applied to the surface of the unit cell case whose normal direction is the stacking direction Tends to be insufficient. When the pressure applied to the surface of the unit cell case with the stacking direction as the normal direction is insufficient, the compression is applied to the interface between the positive electrode layer and the electrolyte layer or the interface between the electrolyte layer and the negative electrode layer. If the force tends to be insufficient, and the compressive force applied to these interfaces becomes insufficient, the performance of the battery tends to deteriorate. Therefore, the technique disclosed in Patent Document 1 has a problem that the effect of improving battery performance tends to be insufficient.

  Then, this invention makes it a subject to provide the battery which can improve performance.

In order to solve the above problems, the present invention takes the following means. That is,
The present invention includes a unit cell having a positive electrode layer, a negative electrode layer, and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and a container for housing the unit cell. Is filled with a fluid capable of pressurizing the unit cell, and the surface of the unit cell does not contact the container, with the direction from one of the positive electrode layer and the negative electrode layer toward the other layer being the normal direction. The battery is characterized by being arranged as described above.

  Here, “the surface of the unit cell is arranged so that the direction from one layer of the positive electrode layer and the negative electrode layer to the other layer is the normal direction and is not in contact with the container” means the stacking direction It means that the unit cell is accommodated in the container so that a fluid to pressurize the unit cell can exist between the surface of the unit cell and the container. Therefore, “the direction of the cell from the one layer of the positive electrode layer and the negative electrode layer to the other layer is the normal direction, and the unit cell surface is arranged so as not to contact the container”. Includes a form in which the unit cell is accommodated in the container such that the surface of the unit cell in a direction intersecting the stacking direction is in contact with the container. In addition, a member capable of allowing fluid to pass (for example, a known porous member) or a member disposed so as to be in contact with only a part of the surface of the unit cell that faces the container includes a unit cell and a container. The unit cell is contained in the container so that the unit cell and the container are not in direct contact with each other. In the present invention, the unit cell accommodated in the container may have a form in which movement in the container is restricted using a positioning member.

  Moreover, in the said invention, the surface of the unit cell parallel to the direction which goes to the other layer from one layer of a positive electrode layer and a negative electrode layer may be contacting the container.

  In the battery of the present invention, the unit cell is accommodated in the container so that the surface of the unit cell whose normal direction is the stacking direction and the container are not in direct contact. By adopting such a configuration, it is possible to uniformly apply a pressing force in the stacking direction of the unit cells using the fluid filled outside the unit cells and inside the container. By uniformly applying a pressing force in the stacking direction of the unit cell, it is easy to reduce resistance when the substance moves at the interface between the positive electrode layer and the electrolyte layer, the interface between the electrolyte layer and the negative electrode layer, etc. It becomes possible to improve the performance. Therefore, according to the present invention, it is possible to provide a battery capable of improving performance.

  In the present invention, the surface of the unit cell parallel to the stacking direction is brought into contact with the container, so that it is easy to prevent the unit cell surface having the stacking direction as the normal direction from contacting the container. Therefore, it becomes easy to improve the performance of a battery by setting it as this form.

It is sectional drawing explaining the battery 10 of this invention. It is sectional drawing explaining the conventional battery 90. FIG. It is sectional drawing explaining the battery 20 of this invention. It is sectional drawing explaining the battery 20 of this invention.

  Hereinafter, the case where the battery of the present invention is a lithium ion secondary battery (solid battery) using a solid electrolyte layer will be described with reference to the drawings. In addition, the form shown below is an illustration of this invention and this invention is not limited to the form shown below.

  FIG. 1 is a cross-sectional view illustrating a battery 10 of the present invention. In FIG. 1, the description of the positive electrode current collector, the positive electrode terminal, the negative electrode current collector, and the negative electrode terminal, and the repeated partial reference numerals are omitted. The horizontal direction in FIG. 1 is the stacking direction.

  As shown in FIG. 1, the battery 10 includes a unit cell 3, 3... Having an electrode body 1 and a film 2 for housing the electrode body 1, and a container 4 for housing the unit cells 3, 3. , And the fluid 5 to be pressurized to the unit cells 3, 3,... In the battery 10, the unit cells 3, 3,... Are accommodated in the container 4 so that the surfaces of the unit cells 3, 3,.

  As shown in FIG. 1, the electrode body 1 has a positive electrode layer 1a, a negative electrode layer 1b, and a solid electrolyte layer 1c sandwiched between the positive electrode layer 1a and the negative electrode layer 1b. The positive electrode layer 1a is connected to a positive electrode terminal (not shown) via a positive electrode current collector (not shown), and the negative electrode layer 1b is connected to a negative electrode terminal (not shown) via a negative electrode current collector (not shown). One end of each of the negative electrode terminal and the negative electrode terminal is located outside the container 4.

  FIG. 2 is a cross-sectional view illustrating a conventional battery 90. In FIG. 2, the description of the positive electrode current collector, the positive electrode terminal, the negative electrode current collector, and the negative electrode terminal, and the repeated partial reference numerals are omitted. The up and down direction in FIG. 2 is the stacking direction. In FIG. 2, the same reference numerals as those used in FIG.

  As shown in FIG. 2, the battery 90 includes the unit cells 3, 3,... So that the surface of the unit cell 3 arranged at the bottom is in the normal direction to the container 4. The battery 10 is configured in the same manner as the battery 10 except that it is housed in the container 4. In the battery 90, the surface of the unit cell 3 arranged at the bottom of the unit 90 is in contact with the container 4 because the stacking direction is the normal direction. Therefore, between the surface of the unit cell 3 and the container 4, There is almost no fluid 5 present. On the other hand, a large amount of fluid 5 can be present between the upper surface of the unit cell 3 arranged at the uppermost portion and the container 4 between the upper surface with the stacking direction as the normal direction. Therefore, in the unit cells 3, 3,..., The pressure applied from the upper side in FIG. 3 is larger than the pressure applied from the lower side in FIG. 3, and a uniform pressure cannot be applied in the stacking direction. In order to improve the performance, the unit cells 3, 3,... That are solid cells are effective to apply a uniform pressure in the stacking direction. It is difficult to improve the performance of the battery 90 having three,.

  On the other hand, in the battery 10, the surfaces of the unit cells 3, 3,... Parallel to the stacking direction are in contact with the container 4. By arranging the unit cells 3,... In this way, it is possible to prevent the surface of the unit cells 3, 3,. By adopting such a configuration, the pressure applied to the cells 3, 3,... From the right side of FIG. 1 and the pressure applied to the cells 3, 3,. Can be made equal to each other, so that a uniform pressing force can be applied in the stacking direction. Since it is possible to improve the performance of the battery by applying a uniform pressure in the stacking direction, according to the present invention, the battery 10 capable of improving the performance can be provided.

  The battery 10 configured as described above can be manufactured through the following steps, for example. When manufacturing the battery 10, first, the electrode body 1 is manufactured through a process of disposing the solid electrolyte layer 1c between the positive electrode layer 1a and the negative electrode layer 1b. The positive electrode layer 1a can be prepared, for example, through a process in which a positive electrode composition prepared by dispersing at least a positive electrode active material and a solid electrolyte in a solvent is applied to the surface of the positive electrode current collector. For example, the negative electrode composition prepared by dispersing a negative electrode active material and a solid electrolyte in a solvent can be prepared through a process of applying to the surface of the negative electrode current collector. The solid electrolyte layer 1c can be produced, for example, through a process in which a composition for electrolyte produced by dispersing a solid electrolyte in a solvent is applied to the surface of the positive electrode layer 1a. When the solid electrolyte layer 1c is thus manufactured, for example, the negative electrode current collector is placed on the solid electrolyte layer 1c formed on the surface of the positive electrode layer 1a so that the solid electrolyte layer 1c is sandwiched between the positive electrode layer 1a and the negative electrode layer 1b. The electrode body 1 can be manufactured through the process of laminating the negative electrode layer 1b formed on the surface and applying compressive force from both ends in the laminating direction. When the electrode body 1 is manufactured in this way, the electrode is formed with the film 2 while not accommodating all of the end of the negative electrode current collector connected to the negative electrode terminal and the end of the positive electrode current collector connected to the positive electrode terminal. The unit cell 3 is produced by wrapping the body 1 and joining the outer edges of the film 2 by a known method such as heat welding. After the unit cell 3 is manufactured, the positive electrode terminal and the positive electrode current collector, which are arranged at the outer side of the container 4, are connected to the negative electrode terminal and the negative electrode, which are arranged at the outer side of the container 4. The unit cells 3, 3,... Are accommodated in the container 4 while the surfaces of the unit cells 3, 3,... Connected to the current collector and parallel to the stacking direction are in contact with the container 4. Thus, when the unit cells 3, 3,... Are accommodated in the container 4, gaps other than the fluid injection path (not shown) connected to the container 4 are closed. The battery 10 can be manufactured through a process of filling the fluid 5 outside the film 2 and inside the container 4 through the fluid injection path and sealing the inlet of the fluid injection path with a sealing material. .

In the battery 10, as the positive electrode active material to be contained in the positive electrode layer 1a, a known positive electrode active material that can be contained in the positive electrode layer of the lithium ion secondary battery can be appropriately used. As such a positive electrode active material, a layered compound such as lithium cobaltate (LiCoO ₂ ) can be exemplified. Moreover, the well-known solid electrolyte which can be contained in the positive electrode layer of a lithium ion secondary battery can be suitably contained in the positive electrode layer 1a. Such solid electrolyte, _Li 3 PO ₄ addition of the oxide-based solid electrolytes such as, _Li 3 PS _{4 and, Li 2 S: P 2 S} 5 = 50: 50~100: 0 become as Li ₂ A sulfide-based solid electrolyte prepared by mixing S and P ₂ S ₅ (for example, mixing Li ₂ S and P ₂ S ₅ so that the molar ratio is Li ₂ S: P ₂ S ₅ = 75: 25) Examples thereof include a sulfide solid electrolyte produced in the above manner. In addition, the positive electrode layer 1a may contain a binder that binds the positive electrode active material and the solid electrolyte and a conductive material that improves conductivity. Examples of the binder that can be contained in the positive electrode layer 1a include butylene rubber, and examples of the conductive material that can be contained in the positive electrode layer 1a include carbon black. Moreover, the known solvent which can be used when preparing the slurry used at the time of preparation of the positive electrode layer of a lithium ion secondary battery can be used suitably at the time of preparation of the positive electrode layer 1a. As such a solvent, heptane and the like can be exemplified.

  Moreover, as a negative electrode active material contained in the negative electrode layer 1b, the well-known negative electrode active material which can be contained in the negative electrode layer of a lithium ion secondary battery can be used suitably. Examples of such a negative electrode active material include graphite. The negative electrode layer 1b can contain a solid electrolyte, and can appropriately contain a known solid electrolyte that can be contained in the negative electrode layer of the lithium ion secondary battery. Examples of such a solid electrolyte include the solid electrolyte that can be contained in the positive electrode layer 1a. In addition, the negative electrode layer 1b may contain a binder that binds the negative electrode active material and the solid electrolyte or a conductive material that improves conductivity. Examples of the binder and conductive material that can be contained in the negative electrode layer 1b include the binder and conductive material that can be contained in the positive electrode layer 1a. Moreover, the said solvent etc. which can be used at the time of preparation of the positive electrode layer 1a can be used suitably at the time of preparation of the negative electrode layer 1b.

  Examples of the solid electrolyte contained in the solid electrolyte layer 1c include the solid electrolyte that can be contained in the positive electrode layer 1a. Moreover, the said solvent etc. which can be used at the time of preparation of the positive electrode layer 1a can be used suitably at the time of preparation of the solid electrolyte layer 1c.

  Moreover, the positive electrode current collector and the negative electrode current collector, as well as the positive electrode terminal and the negative electrode terminal are known positive electrodes and negative electrode current collectors that can be used as the positive electrode terminal and the negative electrode terminal of the lithium ion secondary battery. It can be made of a conductive material. Examples of such a conductive material include one or more elements selected from the group consisting of Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Co, Cr, Zn, Ge, and In. Examples of the metal material to be included can be given.

  Moreover, the film 2 can withstand the environment at the time of use of a lithium ion secondary battery, has a property which does not permeate | transmit a gas and a liquid, and uses the film which can be sealed, without being specifically limited. be able to. Examples of the constituent material of such a film include resin films such as polyethylene, polyvinyl fluoride, and polyvinylidene chloride, and metal deposited films obtained by depositing a metal such as aluminum on these surfaces.

  The container 4 is not particularly limited as long as the container 4 is made of a material that can withstand the environment of the battery 10 and the pressure of the fluid 5. The container 4 can be made of metal such as aluminum or stainless steel.

  The fluid 5 may be an incombustible gas typified by carbon dioxide or the like, or an inert gas typified by helium, nitrogen, argon or the like. In addition, dry air can be used as the fluid 5. However, it is preferable to use the nonflammable gas or the inert gas from the viewpoint of making the battery easy to improve the safety. In the battery 10, the pressure of the fluid 5 that pressurizes the unit cell 3 can be, for example, about 1 to 200 atm.

  In the above description regarding the battery 10, gas is exemplified as the fluid 5, but the fluid 5 in the present invention is not limited to gas. The fluid 5 may be a known liquid, and a solid may be used together with a gas or a liquid.

  Moreover, in the said description regarding the battery 10, although the unit cell 3 which has one electrode body 1 was illustrated, the unit cell with which the battery of this invention is equipped may have a some electrode body. In the case where a unit cell having a plurality of electrode bodies is provided, two adjacent electrode bodies housed in the unit cell case may be electrically connected in series or in parallel.

  In the above description of the present invention, the battery 10 including the unit cells 3, 3,... Having the electrode body 1 that is not wound is illustrated, but the battery of the present invention is not limited to this form. In the battery of the present invention, the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are laminated so that the solid electrolyte layer is disposed between the positive electrode layer and the negative electrode layer, and then wound. A unit cell having the produced electrode body may be provided.

  3A and 3B are cross-sectional views illustrating a battery 20 according to another embodiment of the present invention. 3A and 3B, the battery 20 is shown in a simplified manner. The back / front direction of FIG. 3A and the vertical direction of FIG. 3B are the axial directions of the wound electrode body 21. 3A and 3B, components similar to those of the battery 10 are denoted by the same reference numerals as those used in FIG. 1, and description thereof is omitted as appropriate.

  As shown in FIG. 3A and FIG. 3B, the battery 20 includes a wound electrode body 21 and a unit cell 23 that includes the film 2 that houses the electrode body 21, and a container 4 that houses the unit cell 23. , And the fluid 5 for pressurizing the unit cell 23 is filled outside the film 2 and inside the container 4. In the battery 20, the direction parallel to the paper surface of FIG. 3A is the stacking direction, and as shown in FIG. 3B, the unit cell 23 is placed so that the surface of the unit cell 23 parallel to the stacking direction is in contact with the container 4. Housed in a container 4.

  By disposing the unit cells 23 in this way, it is possible to apply a uniform pressure in the stacking direction using the fluid 5. Therefore, even if the electrode body 21 produced through the winding process is provided, for example, by disposing the unit cell 23 so that the surface of the unit cell 23 parallel to the stacking direction is in contact with the container 4, It becomes possible to provide the battery 20 capable of improving the performance.

  Although the case where this invention is applied to a lithium ion secondary battery was illustrated in the said description regarding this invention, this invention is not limited to the said form. The battery of the present invention can also be configured such that ions other than lithium ions move between the positive electrode layer and the negative electrode layer. Examples of such ions include sodium ions, potassium ions, magnesium ions, calcium ions and the like. In the case where ions other than lithium ions move, the positive electrode active material, the solid electrolyte, and the negative electrode active material may be appropriately selected according to the moving ions.

  Moreover, although the case where this invention is applied to the solid battery which has a solid electrolyte layer was illustrated in the said description regarding this invention, this invention is not limited to the said form. The battery of the present invention may be a battery having an electrolyte layer using an electrolytic solution. However, in order to improve the performance of the solid battery, it is more necessary to pressurize the unit cell uniformly than the battery having the electrolyte layer using the electrolytic solution. Therefore, the battery of the present invention is preferably a solid battery from the viewpoint of easily providing a battery with improved performance.

  Moreover, although the case where this invention is applied to the secondary battery which can be charged / discharged was illustrated in the said description regarding this invention, this invention is not limited to the said form. The battery of the present invention may be a so-called primary battery.

DESCRIPTION OF SYMBOLS 1, 21 ... Electrode body 1a ... Positive electrode layer 1b ... Negative electrode layer 1c ... Solid electrolyte layer (electrolyte layer)
2 ... Film 3, 23 ... Unit cell 4 ... Container 5 ... Fluid 10, 20, 90 ... Battery

Claims (2)

A unit cell having a positive electrode layer, a negative electrode layer, and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and a container for housing the unit cell,
A fluid capable of pressurizing the unit cell is filled outside the unit cell and inside the container,
The direction of the positive electrode layer and the negative electrode layer from one layer to the other is a normal direction, and the surface of the unit cell is disposed so as not to contact the container, battery. The battery according to claim 1, wherein a surface of the unit cell parallel to a direction from one layer of the positive electrode layer and the negative electrode layer to the other layer is in contact with the container. .

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