Electrochemical cell and method for manufacturing the same

Abstract

To provide an electrochemical cell and a manufacturing method for the same.SOLUTION: An electrochemical cell 1 has an electrode body in which a positive electrode body including positive electrode layers 16 on a plurality of positive electrode collectors 19 connected by a positive electrode connection part 20 and a negative electrode body including negative electrode layers 14 on a plurality of negative electrode collectors 11 connected by a negative electrode connection part are folded and piled up between a positive electrode layer 16 and a negative electrode layer 14 with a solid electrolyte layer 15 interposed therebetween. The electrochemical cell 1 has an electrode body that includes the negative electrode layer 14 including negative electrode active material on the plurality of negative electrode collectors 11 connected by the negative electrode connection part, in which a positive and negative composite body in which the positive electrode layers 16 including positive electrode active material are bonded onto the negative electrode layers with the solid electrolyte layer 15 therebetween and the positive electrode body including the plurality of positive electrode collectors 19 connected by the positive electrode connection part 20 are alternately folded and piled up.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an electrochemical cell and a method for manufacturing the same.

Background Art

[0002] As an example of a method for manufacturing an all-solid-state battery, a manufacturing method applying the technology of a multilayer ceramic capacitor (MLCC) is known. In this manufacturing method, for example, a required number of layers such as a positive electrode layer, a negative electrode layer, and an electrolyte layer are stacked and fired together to form a laminate. Next, a conductive paste is applied to the side surface of the laminate and fired at the curing temperature of the conductive paste to connect and collect electricity for each layer.

[0003] For example, in Patent Document 1 below, a negative electrode layer is provided on the upper surface side of a solid electrolyte layer, and a positive electrode active material layer and a positive electrode current collector layer are arranged on the lower surface side to form a laminate. The upper and lower surfaces of the laminate are covered with an exterior material, and an all-solid-state battery having a configuration in which a positive electrode terminal and a negative electrode terminal are provided on the side surface side of the laminate is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above manufacturing method, since each component such as a negative electrode layer, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer having different coefficients of thermal expansion are stacked and fired together, there is a problem that the materials that can be used are limited by the firing temperature. In addition, there is a problem that a material not suitable for firing together cannot be used as a component. For example, when a component having a lower melting point than other components is included among the above components, there is a problem that only the component having a lower melting point melts when fired together.

[0006] Therefore, an object of the present invention is to provide an electrochemical cell having excellent electrical characteristics, which can combine components that cannot be combined in a batch firing without any problem, and can achieve an optimal combination of materials for a solid electrolyte and an electrode material, respectively.

Means for Solving the Problems

[0007] (1) The electrochemical cell according to the present invention includes a positive electrode body having a positive electrode layer containing a positive electrode active material on a plurality of positive electrode current collectors connected by a positive electrode connection portion, and It is a fired body a negative electrode body having a negative electrode layer containing a negative electrode active material on a plurality of negative electrode current collectors connected by a negative electrode connection portion, wherein the positive electrode body and the negative electrode body are with a melting point lower than the firing temperature of the positive electrode layer superposed on each other with a solid electrolyte layer interposed therebetween. and is a fired body at a temperature higher than the melting point of the negative electrode active material It is characterized by having an electrode body.

[0008] According to the above-described electrochemical cell, an electrode body can be formed by combining and superposing a separately formed positive electrode body and negative electrode body. When forming an electrochemical cell as an all-solid-state battery including this electrode body, after separately firing the negative electrode active material provided in the negative electrode body and the positive electrode active material provided in the positive electrode body, the positive electrode body and the negative electrode body are formed, and these are superposed to form an electrode body. Therefore, the need for batch firing is eliminated, and a combination of materials with excellent characteristics can be realized for the positive electrode body and the negative electrode body, respectively. For example, although metallic lithium, which is not suitable for batch firing but has a large single electrode capacity, can be applied as the negative electrode active material provided in the negative electrode layer, the battery characteristics can be improved as an all-solid-state battery.

[0009] (2) The electrochemical cell according to the present invention includes a negative electrode layer containing a negative electrode active material on a plurality of negative electrode current collectors connected by a negative electrode connection portion, and on the negative electrode layer It is a fired body a positive and negative electrode composite in which a positive electrode layer containing a positive electrode active material is attached via a solid electrolyte layer, and a positive electrode body including a plurality of positive electrode current collectors connected by a positive electrode connection portion, and It is a fired body is characterized by having an electrode body formed by alternately superposing them. and the negative electrode active material has a melting point lower than the firing temperatures of the positive electrode layer and the solid electrolyte layer

[0010] According to the above-mentioned electrochemical cell, a positive / negative electrode composite can be formed by combining a separately fabricated positive electrode layer and negative electrode layer, and an electrode body can be formed by laminating this with a positive electrode body. When constructing an electrochemical cell as an all-solid-state battery equipped with this electrode body, after separately firing the negative electrode active material provided in the negative electrode layer and the positive electrode active material provided in the positive electrode layer, a positive / negative electrode composite can be formed, and the electrode body can be formed by laminating it with the positive electrode body. For this reason, there is no need for batch firing, and a combination of materials with excellent characteristics can be realized for the positive electrode layer and the negative electrode layer respectively. For example, although metallic lithium, which is not suitable for batch firing but has a large single electrode capacity, can be applied as the negative electrode active material to be included in the negative electrode layer, the battery characteristics can be improved as an all-solid-state battery.

[0011] (3) In the electrochemical cell according to one embodiment of the present invention, the solid electrolyte layer is an oxide-based solid electrolyte, the positive electrode active material is a carbon-based material or an oxide-based material, and the negative electrode active material can contain un-fired lithium or sulfur. (4) In the electrochemical cell according to one embodiment of the present invention, the solid electrolyte layer is Li 6.25 La 3 Zr 2 Al 0.25 O 12 or Li 1.5 Al 0.5 Ge 1.5 P 3 O 12 or Li 7 La 3 Zr 2 O 12 , the positive electrode active material contains Li 1.3 Al 0.3 Ti 1.7 P 3 O 12 and graphite, and the negative electrode active material can contain un-fired lithium or sulfur. ( 5 ) In the electrochemical cell according to one embodiment of the present invention, a configuration in which the electrode body is housed in a container-shaped exterior body can be adopted.

[0012] By housing the electrode body in the exterior body, an electrochemical cell with a robust configuration that can withstand external forces and loads can be provided.

[0013] (6 )In an electrochemical cell according to one embodiment of the present invention, the electrode body is housed in an exterior body composed of a positive electrode side container and a negative electrode side container, a positive electrode tab connected to the positive electrode current collector is connected to a positive electrode side electrode plate provided in the positive electrode side container, and a negative electrode tab connected to the negative electrode current collector is connected to a negative electrode side electrode plate provided in the negative electrode side container. Such a configuration can be adopted.

[0014] By housing the electrode body in the exterior body, an electrochemical cell having a robust structure that can withstand external forces and loads can be provided. By configuring the exterior body from a positive electrode side container and a negative electrode side container, the positive electrode tab and the negative electrode tab of the electrode body can be easily connected to the positive electrode side electrode plate provided in the positive electrode side container and the negative electrode side electrode plate provided in the negative electrode side container, respectively.

[0015] ( 7 )In an electrochemical cell according to one embodiment of the present invention, the electrode body is housed in an exterior body composed of a positive electrode side container made of a positive electrode side laminate film and a negative electrode side container made of a negative electrode side laminate film, the positive electrode tab of the electrode body is connected to a positive electrode side electrode plate provided in the positive electrode side container, and the negative electrode tab of the electrode body is connected to a negative electrode side electrode plate provided in the negative electrode side container. Such a configuration can be adopted.

[0016] By housing the electrode body in the exterior body, an electrochemical cell having a robust structure that can withstand external forces and loads can be provided. By configuring the exterior body from a laminate film, a lightweight electrochemical cell can be provided. By configuring the exterior body from a positive electrode side container and a negative electrode side container, the positive electrode tab and the negative electrode tab of the electrode body can be easily connected to the positive electrode side electrode plate provided in the positive electrode side container and the negative electrode side electrode plate provided in the negative electrode side container, respectively.

[0017] ( 8 )In an electrochemical cell according to one embodiment of the present invention, a configuration can be adopted in which the peripheral wall portion of the positive electrode side container and the peripheral wall portion of the negative electrode side container are overlapped and heat-sealed.

[0018] The positive electrode side container and the negative electrode side container made of a laminated film can be easily integrated by heat-sealing their peripheral wall portions, and an electrochemical cell having a lightweight and highly airtight exterior can be provided.

[0019] ( 9 ) The manufacturing method of the electrochemical cell according to the present invention is to place It is a fired body containing a positive electrode active material a positive electrode body having a positive electrode layer on a plurality of positive electrode current collectors connected at a positive electrode connection portion, and on a plurality of negative electrode current collectors connected at a negative electrode connection portion containing a negative electrode active material with a melting point lower than the firing temperature of the positive electrode layer a negative electrode body having a negative electrode layer, with and is a fired body at a temperature higher than the melting point of the negative electrode active material a solid electrolyte layer interposed therebetween and folded over each other to form an electrode body, which is then housed in an exterior body.

[0020] The electrode body can be formed by combining and folding a separately created positive electrode body and negative electrode body. When manufacturing an electrochemical cell as an all-solid-state battery equipped with this electrode body, after separately firing the negative electrode active material provided in the negative electrode body and the positive electrode active material provided in the positive electrode body, the positive electrode body and the negative electrode body are formed, and these are folded over each other to form an electrode body. Therefore, there is no need for batch firing, and a combination of materials with excellent characteristics can be realized for the positive electrode body and the negative electrode body respectively. For example, although it is not suitable for batch firing as the negative electrode active material provided in the negative electrode layer, metallic lithium with a large single electrode capacity can be applied, and an electrochemical cell with improved battery characteristics can be manufactured.

[0021] ( 10 ) The manufacturing method of the electrochemical cell according to the present invention is to place has a melting point lower than the firing temperatures of the positive electrode layer and the solid electrolyte layer a negative electrode layer containing a negative electrode active material on a plurality of negative electrode current collectors connected at a negative electrode connection portion, and on this negative electrode layer The fired body via a solid electrolyte layer , the fired body containing a positive electrode active material a positive / negative electrode composite with a positive electrode layer attached, and a positive electrode body having a plurality of positive electrode current collectors connected at a positive electrode connection portion, are alternately folded over each other with a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer to form an electrode body, which is then housed in an exterior body.

[0022] A positive / negative electrode composite can be formed by combining separately fabricated positive electrode layers and negative electrode layers, and an electrode body can be formed by laminating this composite with a positive electrode body. When constructing an electrochemical cell as an all-solid-state battery equipped with this electrode body, after separately firing the negative electrode active material provided in the negative electrode layer and the positive electrode active material provided in the positive electrode layer, a positive / negative electrode composite can be formed and laminated with the positive electrode body to form an electrode body. Therefore, there is no need for batch firing, and combinations of materials with excellent characteristics can be realized for the positive electrode layer and the negative electrode layer, respectively. For example, although a metal lithium with a large single electrode capacity, which is not suitable for batch firing, can be applied as the negative electrode active material included in the negative electrode layer, an all-solid-state battery with improved battery characteristics can be manufactured.

[0023] (11) In the method for manufacturing an electrochemical cell according to the present invention, the solid electrolyte layer is an oxide-based solid electrolyte, the positive electrode active material is a carbon-based material or an oxide-based material, and the negative electrode active material can contain un-fired lithium or sulfur. (12) In the method for manufacturing an electrochemical cell according to the present invention, the solid electrolyte layer is Li 6.25 La 3 Zr 2 Al 0.25 O 12 or Li 1.5 Al 0.5 Ge 1.5 P 3 O 12 or Li 7 La 3 Zr 2 O 12 , the positive electrode active material contains Li 1.3 Al 0.3 Ti 1.7 P 3 O 12 and graphite, and the negative electrode active material can contain un-fired lithium or sulfur. ( 13 ) The manufacturing method of the electrochemical cell according to the present invention is characterized in that the exterior body is composed of a positive electrode side container made of a positive electrode side laminate film and a negative electrode side container made of a negative electrode side laminate film.

[0024] By housing the electrode body in an exterior body, an electro-chemical cell with a robust structure that can withstand external forces and loads can be provided. By configuring the exterior body from a laminate film, a lightweight electro-chemical cell can be provided. By configuring the exterior body from a positive electrode side container and a negative electrode side container, the positive electrode tab and the negative electrode tab of the electrode body can be easily connected to the positive electrode side electrode plate provided in the positive electrode side container and the negative electrode side electrode plate provided in the negative electrode side container, respectively.

[0025] ( 14 ) The method for manufacturing an electro-chemical cell according to the present invention is characterized by heat-sealing the peripheral wall portions of the positive electrode side container and the negative electrode side container after overlapping them.

[0026] The positive electrode side container and the negative electrode side container made of a laminate film can be easily integrated by heat-sealing their peripheral wall portions, and an electro-chemical cell provided with a lightweight and highly airtight exterior body can be provided.

Advantages of the Invention

[0027] In the case of an electro-chemical cell according to the present invention, a separately created positive electrode body and negative electrode body, or separately created positive electrode layers and negative electrode layers can be combined to form a negative electrode body or a positive electrode body, and these can be folded to form an electrode body. When configuring an electro-chemical cell as an all-solid-state battery provided with this electrode body, for example, after separately firing a negative electrode active material and a positive electrode active material, a positive electrode body and a negative electrode body can be formed, and these can be folded to form an electrode body. Therefore, a combination of materials with excellent characteristics can be realized for the positive electrode body and the negative electrode body, respectively. For example, although it is not suitable for batch firing as a negative electrode active material, metallic lithium with a large single electrode capacity can be applied, and the battery characteristics can be improved as an all-solid-state battery.

Brief Description of the Drawings

[0028]

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Embodiments for Carrying Out the Invention

[0029] Hereinafter, embodiments of the electrochemical cell according to the present invention will be described with reference to the drawings. In the following embodiments, as an example of the electrochemical cell, a coin-type all-solid-state battery (hereinafter simply referred to as "battery") will be cited, and the configuration of this battery will be described. In the drawings used in the following description, in order to make each member recognizable in size, the scale of each member is appropriately changed and shown.

[0030] <First Embodiment> Figs. 1 to 4 are drawings showing a first embodiment in which the electrochemical cell according to the present invention is applied to an all-solid-state battery. The battery (electrochemical cell) 1 of the present embodiment is a button-type battery having a circular shape in plan view. This battery 1 includes a container-shaped exterior body 2 and an electrode body 3 housed inside the exterior body 2.

[0031] (Exterior body) As shown in Fig. 4, the exterior body 2 includes a housing portion 4 for housing the electrode body 3 and a sealing portion 5 bent along the outer periphery of the housing portion 4. The sealing portion 5 is bent along the outer periphery of the housing portion 4 by, for example, drawing molding. The exterior body 2 includes a first container (outer container) 7 and a second container (inner container) 8 that sandwich the electrode body 3 therebetween. The first container 7 and the second container 8 are each formed of a laminate film (laminate structure). The laminate film has a metal foil (metal layer), a fusion layer (resin layer) provided on the overlapping surface (inner surface) to cover the metal foil, and a protective layer (resin layer) provided on the outer surface to cover the metal foil. The metal layer is formed of a metal foil that blocks outside air and water vapor and is made of, for example, aluminum or stainless steel. The fusion layer of the overlapping surface is formed of, for example, a single thermoplastic resin or a copolymer such as polyethylene or polypropylene of polyolefin. The protective layer on the outer surface is formed of, for example, the above-mentioned polyolefin, polyester such as polyethylene terephthalate, nylon, or the like.

[0032] The first container (negative electrode side container; outer container) 7 includes a circular first bottom wall portion 6 and a first peripheral wall portion 9 extending in a cylindrical shape from the outer periphery of the first bottom wall portion 6. A first through hole 23 having an inner diameter about one fraction of the inner diameter of the first bottom wall portion 6 is formed at the center of the first bottom wall portion 6. On the inner surface side of the first bottom wall portion 6, a negative electrode side electrode plate 26 such as a nickel plate or a metal plate nickel-plated on a copper plate is thermally welded via a ring-shaped first seal film (negative electrode side seal film) 24. The first seal film 24 is formed by molding a seal film made of a thermoplastic resin such as polyethylene or polypropylene of polyolefin into a ring shape. One side of the first seal film 24 is thermally welded to the first bottom wall portion 6 of the first container 7, and the other side of the first seal film 24 is thermally welded to the negative electrode side electrode plate 26.

[0033] The negative electrode side electrode plate 26 is exposed to the outside of the battery 1 through the first through hole 23 and functions as the negative electrode terminal of the battery 1. The negative electrode tab 13 of the electrode body 3 described later is connected to the negative electrode side electrode plate 26 by a joining means such as ultrasonic welding.

[0034] The second container (positive electrode side container: inner container) 8 includes a disk-shaped second bottom wall portion 31, a second peripheral wall portion 32 extending in a cylindrical shape from the outer peripheral edge of the second bottom wall portion 31, and a bent peripheral wall portion 33 that is bent from the opening edge of the second peripheral wall portion 32 so as to have a U-shaped cross section toward the outside of the second peripheral wall portion 32 and extends toward the second bottom wall portion 31 side. The second bottom wall portion 31 is disposed on the side opposite to the first bottom wall portion 6 of the first container 7 with the electrode body 3 interposed therebetween. The second bottom wall portion 31 is formed to have an outer diameter equivalent to that of the first bottom wall portion 6 of the first container 7. At the center of the second bottom wall portion 31, a second through hole 35 having an inner diameter about one fraction of the inner diameter of the second bottom wall portion 31 is formed.

[0035] On the inner surface side of the second bottom wall portion 31, a positive electrode side electrode plate 38 is heat-sealed via a ring-shaped second seal film (seal film on the positive electrode side) 37. It is preferable that a protective plate made of a nickel plate, an Au-plated plate, etc. is welded to the center of the outer surface of the positive electrode side electrode plate 38. In addition, if a plating layer such as nickel or a nickel alloy is formed on the outer surface of the positive electrode side electrode plate 38, the protective plate may be omitted. The second seal film 37 is formed of a thermoplastic resin, similar to the first seal film 24.

[0036] The central portion of the positive electrode side electrode plate 38 is connected to a positive electrode tab 21 (see FIGS. 8 and 13) of the electrode body 3, which will be described later. Note that in FIG. 2, the tab connection portion is not described because the internal structure is complicated. The positive electrode side electrode plate 38 is made of a stainless steel plate having excellent corrosion resistance such as SUS316 and functions as the positive electrode terminal of the battery 1.

[0037] As shown in FIG. 4, the second peripheral wall portion 32 extends in a cylindrical shape from the outer periphery of the second bottom wall portion 31 toward the first bottom wall portion 6 of the first container 7. The second peripheral wall portion 32 forms the outer periphery of the accommodating portion 4. The bent peripheral wall portion 33 is bent from the end portion on the first bottom wall portion 6 side of the second peripheral wall portion 32 along the second peripheral wall portion 32 so as to be cylindrical toward the second bottom wall portion 31 side. The bent peripheral wall portion 33 is disposed at an interval outside the second peripheral wall portion 32. The second peripheral wall portion 32 is disposed inside the first peripheral wall portion 9. Further, the bent peripheral wall portion 33 is disposed inside the first peripheral wall portion 9, and the fusion layer of the bent peripheral wall portion 33 and the fusion layer of the first peripheral wall portion 9 are heat-fused.

[0038] The sealing portion 5 is formed by fusing the fusion layer of the bent peripheral wall portion 33 and the fusion layer of the first peripheral wall portion 9. Therefore, the outer periphery of the accommodating portion 4 is sealed by the sealing portion 5. With the above structure, the first container 7 and the second container 8 are overlapped and joined to form the exterior body 2. The sealing portion 5 is formed in a cylindrical shape outside the accommodating portion 4. In the accommodating portion 4, a sealed space is formed by overlapping the first container 7 and the second container 8. Specifically, the accommodating portion 4 is defined by the first bottom wall portion 6, the second bottom wall portion 31, and the second peripheral wall portion 32, and is formed in a circular shape in plan view.

[0039] (Electrode body) Figs. 3 to 5 are diagrams showing the electrode body 3 of the present embodiment. The electrode body 3 has a structure in which a plurality of structures in which a negative electrode layer 14 and a positive electrode layer 16 are laminated via an electrolyte layer 15 are laminated. As shown in Fig. 6, the negative electrode body 10 is a strip-shaped structure having a plurality of disc-shaped negative electrode current collectors 11 and a negative electrode connection portion 12 connecting these negative electrode current collectors 11. The negative electrode body 10 is made of, for example, a copper foil. In the negative electrode body 10, a negative electrode layer 14 such as metallic lithium is formed on both the front and back surfaces of the negative electrode current collector 11 by means such as vapor deposition. In the negative electrode body 10 shown in Fig. 6, 10 negative electrode current collectors 11 are provided, and they are linearly connected by a strip-shaped negative electrode connection portion 12. A strip-shaped negative electrode tab 13 is extended from the negative electrode current collector 11 at one end side in the length direction of the negative electrode body 10 so as to extend the arrangement direction of the negative electrode connection portion 12.

[0040] In the negative electrode body 10, the negative electrode current collector 11 provided with the negative electrode tab 13 can be referred to as the first negative electrode current collector 11, and a total of 10 negative electrode current collectors 11 are provided in the negative electrode body 10, namely, the second negative electrode current collector 11 to the tenth negative electrode current collector 11 in order. In the configuration shown in FIG. 6, the negative electrode layer 14 is vapor-deposited only on one side of the first negative electrode current collector 11, and the negative electrode layer 14 on the other side is omitted. The negative electrode layers 14 are vapor-deposited on both the front and back surfaces of the second to tenth negative electrode current collectors 11. The reason for providing the negative electrode layer 14 only on one side of the first negative electrode current collector 11 is that if the negative electrode layer 14 is provided on both sides of the first negative electrode current collector 11, in the case of the folding structure described later, the negative electrode layer 14 on one surface of the first negative electrode current collector 11 will be exposed, so as to avoid accidental reactions. If there is no concern about the aforementioned accidental reactions, the negative electrode layer 14 may be provided on both sides of the first negative electrode current collector 11.

[0041] FIG. 7 shows a positive-negative electrode composite body 17 in which a positive electrode layer 16 is attached via an electrolyte layer 15 to the surface sides of the negative electrode layers 14 on both sides of the negative electrode body 10 shown in FIG. 6. In the positive-negative electrode composite body 17, the positive electrode layer 16 is attached via the electrolyte layer 15 only to the side where the negative electrode layer 14 is provided on the first negative electrode current collector 11. In addition, flat-plate-shaped electrolyte layers 15 and positive electrode layers 16 are attached to both the front and back surfaces of the second to tenth negative electrode current collectors 11. The surface of the electrolyte layer 15 is shown in FIG. 9, and the state where the positive electrode layer 16 is attached to the surface of the electrolyte layer 15 is shown in FIG. 10. In order to facilitate the folding structure described later, it is preferable to provide a flat portion 15a in which a part of the outer peripheral edge of the electrolyte layer 15 is cut out. In the example shown in FIGS. 9 and 10, four flat portions 15a are formed at 90° intervals around the outer periphery of the electrolyte layer 15.

[0042] FIG. 8 shows a positive electrode body 18, and this positive electrode body 18 has a strip-like structure in which ten disc-shaped positive electrode current collectors 19 made of aluminum foil are linearly connected by a positive electrode connection portion 20 made of aluminum foil. A strip-shaped positive electrode tab 21 is formed on the positive electrode current collector 19 at one end side in the length direction of the positive electrode body 18 so as to extend in the arrangement direction of the positive electrode connection portion 20.

[0043] The electrode body 3 is configured by alternately folding and stacking the positive-negative electrode composite body 17 shown in FIG. 7 and the positive electrode body 18 shown in FIG. 8. As an example, as shown in FIG. 11, the positive-negative electrode composite 17 is arranged obliquely sideways in the front direction with the negative electrode tab 13 and the first negative electrode current collector 11 positioned on the left side. On the other hand, the positive electrode body 18 and the positive-negative electrode composite 17 are arranged in an L shape such that the tenth positive electrode current collector 19 of the positive electrode body 18 approaches the first negative electrode current collector 11 of the positive-negative electrode composite 17.

[0044] From this state, as shown in FIG. 12, the tenth positive electrode current collector 19 of the positive electrode body 18 is stacked on the first positive electrode layer 16 of the positive-negative electrode composite 17, and after stacking, the positive-negative electrode composite 17 and the positive electrode body 18 are alternately folded at their negative electrode connection portions 12 or positive electrode connection portions 20. By this folding process, the tenth positive electrode current collector 19 of the positive electrode body 18 can be folded on the first positive electrode layer 16 of the positive-negative electrode composite 17. Thereafter, the second positive electrode layer 16 of the positive-negative electrode composite 17 is stacked on the tenth positive electrode current collector 19 of the positive electrode body 18, and then a folding process of folding the ninth positive electrode current collector 19 of the positive electrode body 18 on the second positive electrode layer 16 of the positive-negative electrode composite 17 is performed. In this way, while alternately folding the positive-negative electrode composite 17 and the positive electrode body 18 in order, the current collectors are stacked on each other, and by folding back the last positive electrode tab 21, an electrode body 3 having a folded structure with the positive electrode tab 21 folded back on the positive electrode side as shown in FIG. 13 can be obtained. Further, by folding back the negative electrode tab 13, the negative electrode tab 13 on the negative electrode side of the electrode body 3 is folded back to the negative electrode side of the electrode body 3 as shown in FIG. 14.

[0045] As described above, a negative electrode layer 14 containing a negative electrode active material is provided on a plurality of negative electrode current collectors 11 connected by the negative electrode connection portion 12, and a positive-negative electrode composite 17 with a positive electrode layer 16 containing a positive electrode active material attached thereon via a solid electrolyte layer 15, and a positive electrode body 18 having a plurality of positive electrode current collectors 19 connected by the positive electrode connection portion 20 can be alternately folded to obtain an electrode body 3. Alternatively, the electrode body 3 can also be described as an electrode body in which a positive electrode body having a positive electrode layer 16 containing a positive electrode active material on a plurality of positive electrode current collectors 19 connected by a positive electrode connection portion 20 and a negative electrode body 10 having a negative electrode layer 14 containing a negative electrode active material on a plurality of negative electrode current collectors 11 connected by a negative electrode connection portion 12 are stacked on top of each other with a solid electrolyte layer 15 interposed between the positive electrode layer 16 and the negative electrode layer 14.

[0046] In the above configuration, as an example, the negative electrode layer 14 is composed of a vapor deposition film of metallic lithium vapor deposited by a resistance heating vapor deposition method or the like. Alternatively, the negative electrode layer 14 may be a layer of metallic lithium attached by a thermal pressure bonding method such as hot pressing or an adhesion method using an alloying reaction.

[0047] To manufacture the electrolyte layer 15, a slurry is prepared by mixing a solid electrolyte, a binder, a solvent, a dispersant, a plasticizer, etc. This slurry is coated on the surface of a carrier film to a required thickness by a sheet forming method or the like, and this coated material is peeled off from the carrier film and fired in an electric furnace or the like to obtain a solid electrolyte sheet. For the firing atmosphere, an atmosphere containing oxygen is preferable in order to suppress oxygen deficiency. When there are concerns about the influence of moisture, it is even more preferable to select a dry atmosphere. When firing, it is preferable to sandwich the solid electrolyte sheet between a ceramic plate (made of Al2O3, MgO, etc.) or a graphite plate in order to suppress distortion of the solid electrolyte sheet. In order to suppress the reaction with the ceramic plate and the volatilization of Li, a sheet made of the same material as the solid electrolyte or an oxide containing Li may be inserted between the ceramic plate.

[0048] A positive electrode slurry (a mixture of a positive electrode active material, a binder, a conductive assistant, a solvent, a dispersant, etc.) is coated on one surface of the solid electrolyte sheet obtained as described above, fired, and integrated. Alternatively, in a manner similar to the above-described method, a coating applied onto a carrier film can be peeled off from the carrier film and fired to produce a positive electrode sheet. It can be attached to the above-described solid electrolyte sheet by thermocompression bonding using hot pressing or the like and fired to integrate them. Through these processes, a laminate including the solid electrolyte layer 15 and the positive electrode layer 16 can be obtained.

[0049] Next, the previous electrolyte layer 15 and the negative electrode layer 14 are adhered. For adhesion, a thermocompression bonding method using hot pressing or a method of forming a metal (such as In, Cu, Al, Au, etc.) on the electrolyte layer 15 by a film-forming method such as sputtering and alloying with lithium can be used for adhesion. After that, using the positive electrode body 18 shown in FIG. 11 and the positive and negative electrode composite body 17 obtained as described above, they are alternately stacked while being folded in the procedures shown in FIGS. 11 to 12, and a conductive paste or the like is applied during the stacking. After stacking, it is heated to the melting temperature of the conductive paste and cooled after heating to obtain the electrode body 3.

[0050] Once the electrode body 3 is obtained, it is housed inside the exterior body 2, and the negative electrode tab 13 is joined to the negative electrode side electrode plate 26 of the first container 7 and the positive electrode tab 21 is joined to the positive electrode side electrode plate 38 of the second container 8 by a joining method such as attachment with a conductive paste or welding, and the battery 1 can be obtained by heat-sealing the peripheral wall portions of the first container 7 and the second container 8. Welding of the tabs may use any method such as laser welding, resistance welding, ultrasonic welding, etc. Also, a metal plate of Ni or Al or a metal plate with good corrosion resistance such as a stainless steel plate may be attached to the outer surface sides of the negative electrode side electrode plate 26 and the positive electrode side electrode plate 38.

[0051] Also, in the above-described manufacturing method, the manufacturing pattern and order are not particularly limited, and various methods can be adopted. For example, the positive electrode layer 16 is attached to the positive electrode current collector 19 of the positive electrode body 18 with a conductive paste and dried, and then folded over the negative electrode current collector 11 of the negative electrode body 10 including the negative electrode layer 14 made of lithium. Each time it is folded, the electrolyte layer 15 is sandwiched between them. Finally, the electrode body 3 can be obtained by hot pressing or by attaching the electrolyte layer 15 and the lithium negative electrode layer 14 through alloying. Alternatively, the negative electrode body 10 and the electrolyte layer (electrolyte sheet) 15 can be fabricated and attached to the positive electrode body 18 provided with the positive electrode layer 16, and the negative electrode body 10 can be folded. Also, sheets of the negative electrode layer 14, the electrolyte layer 15, and the positive electrode layer 16 can be fabricated and attached to the positive electrode body 18 and the negative electrode body 10 while folding them, and an appropriate method such as this can be selected. In this way, an electrode body can be obtained in which a positive electrode body having a positive electrode layer 16 containing a positive electrode active material on a plurality of positive electrode current collectors 19 connected by the positive electrode connection portion 20 and a negative electrode body 10 having a negative electrode layer 14 containing a negative electrode active material on a plurality of negative electrode current collectors 11 connected by the negative electrode connection portion 12 are overlapped with each other with a solid electrolyte layer 15 interposed between the positive electrode layer 16 and the negative electrode layer 14.

[0052] There are no particular restrictions on the materials used when manufacturing the above-described battery 1, but the following can be exemplified. · Positive electrode active material or negative electrode active material: Carbon-based materials such as soft carbon and hard carbon, lithium, sulfur. Oxides containing or not containing Li can be used. · Electrolyte: Oxides, sulfides, hydrides, polymers, etc. containing Li can be used. · Conductive aid: Carbon black, acetylene black, etc. can be added. · Material of the current collector: Copper, aluminum, SUS, nickel, etc. can be selected. · Binder: A binder for a ceramic green sheet, a non-aqueous resin such as PVA (polyvinyl alcohol), PVB (polyvinyl butyral), or acrylic, or an aqueous resin such as methyl cellulose can be selected. · Solvent: Water, alcohol-based, ketone-based, etc. can be selected. · A dispersant and a plasticizer may be added. General dispersants and plasticizers used during the production of the green sheet can be added.

[0053] · Dimensions of the battery: The thickness of each of the positive electrode layer, negative electrode layer, and electrolyte layer can be 100 μm or less. The diameter can be 20 mm or less. · The thickness of the current collector foil can be 20 μm or less. · Exterior packaging: Any one of metal laminate, metal can, resin coating, or oxide coating can be selected. · Shape of the electrode body: Examples include circular, elliptical, polygonal, etc.

[0054] Firing temperature of each material Composition of the solid electrolyte layer: Li 6.25 La3Zr2Al 0.25 O 12 In the case of, firing conditions: Conditions such as 1150 °C and air atmosphere can be selected. Composition of the positive electrode layer: Li 1.3 Al 0.3 Ti 1.7 P3O 12 In the case of, a mixture with graphite can be selected, and for firing conditions: To suppress the combustion of graphite, a nitrogen, argon, or vacuum atmosphere can be selected at 800 °C. Composition of the negative electrode layer: Lithium (unfired) can be selected as the negative electrode active material.

[0055] · Those that cannot be fired in one batch For a general oxide-based solid electrolyte such as Li 1.5 Al 0.5 Ge 1.5 P3O 12 (LAGP), etc., the firing temperature of the glass-ceramic system is about 800 °C. For Li7La3Zr2O 12 (LLZ), etc., the crystal system is 1000 °C or higher. Therefore, as active materials, lithium (melting point about 180 °C), which is attracting attention for its high energy density, sulfur (melting point 115 °C), etc. cannot be used as battery constituent materials in the case of one-batch firing. Aluminum (melting point about 660 °C), which is common as a current collector material, also cannot be used. In contrast, in the above examples, since the positive electrode layer and negative electrode layer can be fired separately, a combined structure of these materials with significantly different melting points can be applied. Therefore, an electrochemical cell 1 with excellent battery characteristics can be obtained.

[0056] "Method for manufacturing a laminated container" When manufacturing the battery 1 provided with the exterior body 2 having the laminated structure shown in FIGS. 1 to 4, it can be manufactured by the method described below based on FIGS. 15 to 17. For example, prepare the disk-shaped first container material 115 shown in FIG. 15 of the laminated structure and the hat-shaped second container material 116 of the laminated structure. The electrode body 3 is accommodated inside the protrusion 117 of the second container material 116, each electrode is connected, the outer peripheral portion 116a of the second container material 116 and the outer peripheral portion 115a of the first container material 115 are overlapped and joined by a joining method such as thermal welding to form the joined body 118 shown in FIG. 15. Next, as shown in FIG. 16, prepare a mold 120 composed of a lower mold 121 and an upper mold 122 and a punch 123. Forming holes 121a and 122a into which the protrusion 117 of the joined body 118 can be loosely inserted are formed in the central portions of the lower mold 121 and the upper mold 122, and the outer peripheral portion of the joined body 118 is clamped between the lower mold 121 and the upper mold 122.

[0057] In addition, a forming protrusion 124 composed of an annular wall is provided at the upper end portion of the punch 123, and the punch 123 can be raised from the position shown in FIG. 16 while the outer peripheral portion of the joined body 118 is clamped between the lower mold 121 and the upper mold 122. As shown in FIG. 17, when the forming protrusion 124 is raised from the forming hole 121a to 122a, the outer peripheral portion of the joined body 118 can be cut from the outer peripheral edge portion of the joined body 118 while being processed into a reverse U-shaped cross section by the forming protrusion 124 over the entire circumference. By this pressing process, the battery 1 provided with the exterior body 2 shown in FIGS. 1 to 4 can be obtained.

[0058] "Second example of the electrode body with a folded structure" In the previous embodiment, when folding the positive and negative electrode composite body and the positive electrode body, in each case, the strip-shaped positive and negative electrode composite body 17 and the positive electrode body 18 in which the current collectors are linearly connected were used, but the configurations of the positive and negative electrode composite body 17 and the positive electrode body 18 can adopt various forms. For example, as shown in FIG. 18, an L-shaped positive-negative electrode composite body 53 and a positive electrode body 56 can both be used. The positive-negative electrode composite body 53 has a plurality of electrode portions 53b in which a circular negative electrode layer, an electrolyte layer, and a positive electrode layer are laminated, and these plurality of electrode portions 53b are connected via a strip-shaped electrode connection portion 53a so as to form an L-shape as a whole. The positive electrode body 56 has a plurality of circular positive electrode current collectors 56b, and these plurality of positive electrode current collectors 56b are connected via a strip-shaped electrode connection portion 56a so as to form an L-shape as a whole.

[0059] Using the L-shaped positive-negative electrode composite body 53 and the positive electrode body 56 shown in FIG. 18, the positive electrode current collector 56b located in the bent peripheral wall portion of the positive electrode body 56 is overlapped with the electrode portion 53b located in the bent peripheral wall portion of the positive-negative electrode composite body 53, and the process of alternately folding in the order of (1)→(2)→(3)→(4) is repeated to manufacture an electrode body with a folded structure. In FIG. 18, reference numeral 13 indicates a negative electrode tab, and reference numeral 21 indicates a positive electrode tab 21. By folding back these negative electrode tabs 13 and positive electrode tabs 21 on the upper surface side and the lower surface side of the laminate, respectively, an electrode body having the same structure as the electrode body 3 shown in FIGS. 13 and 14 can be obtained.

[0060] "The Third Example of the Electrode Body with a Folded Structure" In the previous embodiment, when folding the positive-negative electrode composite body and the positive electrode body, in each case, the strip-shaped positive-negative electrode composite body 17 and the positive electrode body 18 in which the current collectors are linearly connected were used, and they were folded back from the ends of the positive-negative electrode composite body 17 and the positive electrode body 18. However, in the case of a folded-back structure, it is also possible to form a folded-back structure after overlapping the central portions in the length direction of the positive-negative electrode composite body 17 and the positive electrode body 18.

[0061] For example, as shown in FIG. 19, a linear positive-negative electrode composite body 63 and a positive electrode body 66 can be used. The positive-negative electrode composite body 63 has a plurality of electrode portions 63b in which a circular negative electrode layer, an electrolyte layer, and a positive electrode layer are laminated, and these plurality of electrode portions 63b are linearly connected via a strip-shaped electrode connection portion 63a. The positive electrode body 66 has a plurality of circular positive electrode current collectors 66b, and these plurality of positive electrode current collectors 66b are linearly connected via a strip-shaped electrode connection portion 66a.

[0062] Using the linear positive and negative electrode composite 63 and the positive electrode body 66 shown in FIG. 19, the positive electrode current collector 66b located at the center in the length direction of the positive electrode body 66 is overlapped with the electrode portion 63b located at the center in the length direction of the positive and negative electrode composite 63, and the process of alternately folding in order in the order of (1)→(2)→(3)→(4) is repeated, whereby an electrode body having a folded structure can be manufactured. In FIG. 19, reference numeral 13 indicates a negative electrode tab, and reference numeral 21 indicates a positive electrode tab 21. By folding back these negative electrode tab 13 and positive electrode tab 21 on the upper surface side and the lower surface side of the laminate respectively, an electrode body having the same structure as the electrode body 3 shown in FIGS. 13 and 14 can be obtained.

[0063] In the present invention, as described above, various shapes can be adopted for the positive and negative electrode composite and the positive electrode body, and various shapes can also be adopted for the folded structure, and of course, it is not limited to the examples described so far. In addition, as an example of the electrochemical cell according to the present invention, the planar circular button-shaped exterior body 2 composed of the above-described first container 7 and second container 8 made of a laminate film has been cited. However, the present invention is not limited to this, and either one or both of the first container and the second container may be made of metal. Further, an exterior body using a bottomed cylindrical metal positive electrode can, a lid-shaped metal negative electrode can for closing the opening of the positive electrode can, and a gasket for insulating the positive electrode can and the negative electrode can may be used, and the shape and structure of the exterior body can be widely applied to general ones for batteries.

Explanation of reference numerals

[0064] 1… Battery (electrochemical cell), 2… Exterior body, 3… Electrode body, 7… Negative electrode side container (first container), 8… Positive electrode side container (second container), 9… First peripheral wall portion, 10… Negative electrode body, 11… Negative electrode current collector, 12… Negative electrode connection portion, 13… Negative electrode tab, 14… Negative electrode layer, 15… Electrolyte layer, 16… Positive electrode layer, 17… Positive and negative electrode composite, 18… Positive electrode body, 19… Positive electrode current collector, 20… Positive electrode connection portion, 21… Positive electrode tab, 26… Negative electrode side electrode plate, 33… Bent peripheral wall portion, 38… Positive electrode side electrode plate, 53, 63… Positive and negative electrode composite.

Claims

1. A positive electrode body having a positive electrode layer which is a fired body containing a positive electrode active material on a plurality of positive electrode current collectors connected to a positive electrode connection portion, and a negative electrode body having a negative electrode layer containing a negative electrode active material having a melting point lower than the firing temperature of the positive electrode layer on a plurality of negative electrode current collectors connected to a negative electrode connection portion, wherein a solid electrolyte layer which is a fired body at a temperature higher than the melting point of the negative electrode active material is interposed between the positive electrode layer and the negative electrode layer, and the electrode bodies are stacked on each other. An electrochemical cell characterized by having

2. A positive-negative electrode composite body having a negative electrode layer containing a negative electrode active material on a plurality of negative electrode current collectors connected to a negative electrode connection portion, and a positive electrode layer which is a fired body containing a positive electrode active material pasted thereon via a solid electrolyte layer which is a fired body on the negative electrode layer, and a positive electrode body having a plurality of positive electrode current collectors connected to a positive electrode connection portion, and the electrode bodies are alternately stacked, and the negative electrode active material has a melting point lower than the firing temperatures of the positive electrode layer and the solid electrolyte layer. An electrochemical cell characterized by having

3. The electrochemical cell according to claim 1 or claim 2, wherein the solid electrolyte layer is an oxide-based solid electrolyte, the positive electrode active material is a carbon-based material or an oxide-based material, and the negative electrode active material contains unfired lithium or sulfur.

4. The electrochemical cell according to claim 1 or claim 2, wherein the solid electrolyte layer is Li 6.25 La 3 Zr 2 Al 0.25 O 12 or Li 1.5 Al 0.5 Ge 1.5 P 3 O 12 or Li 7 La 3 Zr 2 O 12, the positive electrode active material contains Li 1.3 Al 0.3 Ti 1.7 P 3 O 12 and graphite, and the negative electrode active material contains unfired lithium or sulfur.

5. The electrochemical cell according to any one of claims 1 to 4, wherein the electrode body is housed in a container-shaped exterior body.

6. The electrochemical cell according to any one of claims 1 to 4, wherein the electrode body is housed in an exterior body composed of a positive electrode side container and a negative electrode side container, a positive electrode tab connected to the positive electrode current collector is connected to a positive electrode side electrode plate provided in the positive electrode side container, and a negative electrode tab connected to the negative electrode current collector is connected to a negative electrode side electrode plate provided in the negative electrode side container.

7. The electrochemical cell according to any one of claims 1 to 4, characterized in that the electrode body is housed in an exterior body composed of a positive electrode side container made of a positive electrode side laminate film and a negative electrode side container made of a negative electrode side laminate film, and a positive electrode tab of the electrode body is connected to a positive electrode side electrode plate provided in the positive electrode side container, and a negative electrode tab of the electrode body is connected to a negative electrode side electrode plate provided in the negative electrode side container.

8. The electrochemical cell according to claim 7, characterized in that a peripheral wall portion of the positive electrode side container and a peripheral wall portion of the negative electrode side container are overlapped and heat-sealed.

9. A positive electrode body having a positive electrode layer which is a fired body containing a positive electrode active material on a plurality of positive electrode current collectors connected at a positive electrode connection portion, and a negative electrode body having a negative electrode layer containing a negative electrode active material having a melting point lower than the firing temperature of the positive electrode layer on a plurality of negative electrode current collectors connected at a negative electrode connection portion are overlapped with each other with a solid electrolyte layer which is a fired body at a temperature higher than the melting point of the negative electrode active material interposed therebetween to form an electrode body, and the electrode body is housed in an exterior body. A method for manufacturing an electrochemical cell, characterized by comprising the steps of:

10. A positive-negative electrode composite body having a negative electrode layer containing a negative electrode active material having a melting point lower than the firing temperatures of the positive electrode layer and the solid electrolyte layer on a plurality of negative electrode current collectors connected at a negative electrode connection portion, and having the solid electrolyte layer which is a fired body interposed therebetween and the positive electrode layer which is a fired body containing a positive electrode active material pasted thereon, and a positive electrode body having a plurality of positive electrode current collectors connected at a positive electrode connection portion are alternately overlapped with a solid electrolyte layer interposed therebetween to form an electrode body, and the electrode body is housed in an exterior body. A method for manufacturing an electrochemical cell, characterized by comprising the steps of:

11. The method for manufacturing an electrochemical cell according to claim 9 or claim 10, characterized in that the solid electrolyte layer is an oxide-based solid electrolyte, the positive electrode active material is a carbon-based material or an oxide-based material, and the negative electrode active material contains unfired lithium or sulfur.

12. The electrochemical cell according to claim 9 or claim 10, characterized in that the solid electrolyte layer is Li 6.25 La 3 Zr 2 Al 0.25 O 12 or Li 1.5 Al 0.5 Ge 1.5 P 3 O 12 or Li 7 La 3 Zr 2 O 12, the positive electrode active material contains Li 1.3 Al 0.3 Ti 1.7 P 3 O 12 and graphite, and the negative electrode active material contains unfired lithium or sulfur.

13. The method for manufacturing an electrochemical cell according to claim 7 or claim 10, wherein the exterior body is composed of a positive electrode side container made of a positive electrode side laminate film and a negative electrode side container made of a negative electrode side laminate film.

14. The method for manufacturing an electrochemical cell according to claim 13, wherein the peripheral wall of the positive electrode side container and the peripheral wall portion of the negative electrode side container are overlapped and heat-sealed.

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