Structures and their manufacturing methods

Abstract

The present invention provides a structure capable of improving strength and a method for manufacturing the same. [Solution] According to the embodiment, a structure 1 is provided which includes a molded body formed by rolling a dry mixture of powders. The powder includes particles and a binder which includes polytetrafluoroethylene and a first fibrous material of a resin different from polytetrafluoroethylene.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to structures and methods for manufacturing the same. [Background technology]

[0002] In electrodes used in batteries such as primary and secondary batteries, fuel cells, and electrochemical devices such as capacitors, the use of polytetrafluoroethylene (PTFE) as a binder to connect main materials such as active materials is being considered.

[0003] Electrodes using PTFE as a binder have sufficient strength against external forces applied in a specific direction, but they have the problem of not being strong enough when forces are applied in other directions. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2005 / 008807 [Overview of the project] [Problems that the invention aims to solve]

[0005] The problem that this invention aims to solve is to provide a structure capable of improving strength and a method for manufacturing the same. [Means for solving the problem]

[0006] According to one embodiment, a structure is provided which includes a molded body formed by rolling a dry mixture of powders. The powder comprises particles and a binder which includes polytetrafluoroethylene and a first fibrous material of a resin different from polytetrafluoroethylene.

[0007] According to the embodiment, a powder comprising particles and a binder containing polytetrafluoroethylene and a first fiber body of a resin different from polytetrafluoroethylene is dry-mixed. The dry mixture obtained by dry mixing is formed by rolling. A method for manufacturing a structure is provided, which includes the following. [Brief explanation of the drawing]

[0008] [Figure 1] A plan view showing an electrode, which is an example of a powder structure according to the embodiment. [Figure 2] A cross-sectional view of the electrode shown in Figure 1, cut along the line II-II. [Figure 3] A cross-sectional view of the electrode shown in Figure 1, cut along the line III-III. [Figure 4] A schematic diagram of an example of the first step in the method for manufacturing electrodes according to the embodiment. [Figure 5] A schematic diagram of an example of the second step in the method for manufacturing electrodes according to the embodiment. [Figure 6] A schematic diagram of an example of the third step in the method for manufacturing electrodes according to the embodiment. [Figure 7] A schematic diagram of an example of the fourth step in the method for manufacturing electrodes according to the embodiment. [Figure 8] A perspective view showing an example of an electrode manufactured by the method of the embodiment. [Figure 9] An exploded perspective view of an example of a battery equipped with electrodes according to an embodiment. [Figure 10] A partial unfolded perspective view of the electrode group used in the battery shown in Figure 9. [Modes for carrying out the invention]

[0009] The structures of the embodiments are applicable to, for example, batteries (primary batteries, secondary batteries), fuel cells, ceramic products, and the like.

[0010] <Electrode of the first embodiment> An example of applying the structure of the embodiment to an electrode for a battery will be described with reference to FIGS. 1 to 10. The electrode is used, for example, in a primary battery or a secondary battery. In each figure, it is assumed that the thickness direction of the electrode is parallel to the z-axis direction, the short side direction of the electrode is parallel to the x-axis direction, the long side direction of the electrode is parallel to the y-axis direction, and the main surface of the electrode is parallel to the xy plane. The x-axis, y-axis, and z-axis intersect each other substantially perpendicularly.

[0011] As shown in FIGS. 1 to 3, the electrode 1 includes a current collector 2 as a base material, active material-containing layers 3a and 3b as molded bodies, intermediate layers 4a and 4b, and insulating layers 5a and 5b. The current collector 2 has, for example, a rectangular plate shape. The intermediate layers 4a and 4b are formed on both surfaces of the current collector 2 along the xy plane, excluding the end portions on both sides in the short side direction x. The active material-containing layers 3a and 3b are respectively formed on the intermediate layers 4a and 4b. The insulating layers 5a and 5b are respectively formed on the intermediate layers 4a and 4b. The intermediate layers 4a and 4b, the active material-containing layers 3a and 3b, and the insulating layers 5a and 5b are not provided at the end portions 6 on both sides in the short side direction x of the current collector 2. The end portions 6 can function as current collector tabs. The intermediate layer and the insulating layer can be formed, for example, by coating, electrospinning, melt spinning, melt blowing, or the like.

[0012] Next, the configuration of each layer will be described.

[0013] The current collector can be a conductive sheet. Examples of the conductive sheet include a foil made of a conductive material and a porous plate made of a conductive material. Examples of the conductive material include aluminum, aluminum alloy, stainless steel, nickel, copper, and the like. One type or two or more types of conductive materials can be used for the current collector. The thickness of the current collector can be, for example, 1 μm or more and 100 μm or less.

[0014] The active material-containing layer is a molded body formed by rolling a dry mixture in which a powder containing active material particles and a binder is dry-mixed. The powder may contain a conductive agent. The dry mixing is mixing without adding a solvent to the powder, but adding a small amount of solvent to the powder is allowed. Depending on the type or particle size of the material, the fluidity of the powder may be low. By adding a small amount of solvent to the powder, the fluidity of the powder is stabilized and uniform film formation becomes possible. It is desirable that the particles such as active material particles and conductive agents contained in the molded body are dry particles not wetted by the solvent.

[0015] Examples of the active material particles include particles capable of occluding and releasing ions of alkali metals such as Li. Specific examples include lithium transition metal composite oxides, metal oxides, carbon materials such as graphite, tin-silicon-based alloy materials, metal sulfides, metal nitrides, etc. Examples of the lithium transition metal composite oxide include LiCoO2, LiNi 1-x Co x O2(0≦x≦0.3), LiMn x Ni y Co z O2(0≦x≦0.5, 0≦y≦0.5, 0≦z≦0.5), LiMn 2-x M x O4(M is at least one element selected from the group consisting of Mg, Co, Al and Ni, 0≦x≦0.2), LiMPO4(M is at least one element selected from the group consisting of Fe, Co and Ni), etc. Examples of the metal oxide include lithium titanium-containing oxides, niobium-containing oxides, titanium-containing oxides, etc. Examples of the lithium titanium-containing oxide include lithium titanate having a spinel structure (e.g. Li 4+x Ti5O 12 (0≦x≦3)), lithium titanate having a lamellarite structure (e.g. Li 2+y Ti3O7(0≦y≦3)). Examples of the niobium-containing oxide include niobium titanium-containing oxides such as Nb2TiO7. The type of the active material particles can be one type or two or more types.

[0016] The content of active material particles in the active material-containing layer can be, for example, 70% by mass or more and 100% by mass or less.

[0017] The thickness of the active material-containing layer can be, for example, 5 μm to 500 μm.

[0018] The binder contains polytetrafluoroethylene (PTFE) and a first fiber made of a resin different from polytetrafluoroethylene. PTFE undergoes fibrillation (fiber formation) when the powder mixture is rolled. Fibrillation is more likely to occur along the rolling direction (e.g., the long side direction y). Furthermore, the fibrillation of PTFE can be accelerated by heating. Increasing the shear force due to rolling stretches the material into a thin film, but external forces perpendicular to the rolling direction become more likely to act on it. PTFE fibers can suppress damage such as cracking and fracturing that occurs in the active material-containing layer due to external forces applied along the rolling direction.

[0019] The first fibrous material is a fibrous material made of a resin different from PTFE. Therefore, the first fibrous material does not fibrillate upon rolling, but has a fibrous shape even before rolling. At least a portion of the first fibrous material retains its fibrous shape even after rolling. Consequently, the first fibers can be dispersed on the electrode in random directions. Therefore, the first fibers can reduce the occurrence of damage such as cracks and tears in the active material-containing layer due to external forces applied in a direction different from the rolling direction, for example, along the short side direction x.

[0020] The first fiber is formed, for example, by electrospinning, melt spinning, or meltblowing.

[0021] Examples of resins that form the first fiber include polyimide, polyamide, polyamide-imide, polyvinylidene fluoride (PVdF), cellulose, polyolefin, polyether, polyetherimide, polyketone, polysulfone, polyethersulfone, polymethacrylic acid (PMMA), polyvinyl alcohol (PVA), polyvinyl acetal, and copolymers of isobutylene and maleic anhydride. Examples of polyolefins include polypropylene (PP) and polyethylene (PE). One or more types of resin can be used. The above types of resins are soluble in solvents. Therefore, the above types of resins can be molded into fiber shapes by electrospinning. For example, polyimide and PVdF are generally considered difficult to form into fibers. By employing electrospinning, these materials can also be formed into fibers. Furthermore, the resin may have the property of melting when heated. The first fiber can be fixed to active material particles and conductive agent particles by melting when heated. This allows for bonding between active material particles and between active material particles and the conductive agent. Examples of preferred resins include PVdF, cellulose, PMMA, and PVA. A more preferred resin is PVdF.

[0022] The first fiber structure preferably includes at least one of the following: multiple types of fibers with different average diameters, or multiple types of fibers with different melting temperatures. The first fiber structure preferably has a thickness greater than that of the PTFE fibers (fibrils). Multiple types of fibers with different average diameters can improve the strength of the electrode. By varying the melting temperatures of the fibers, the first fiber structure can be partially melted. As a result, the electrode strength can be improved by the first fiber structure, while the adhesion strength between the active material-containing layer and the current collector can be increased.

[0023] The diameter of the first fiber is preferably less than or equal to the electrode thickness. The diameter of the first fiber can be, for example, several hundred nanometers to several tens of micrometers. Furthermore, it is desirable that the ratio of fiber length to diameter of the first fiber is greater than 1.

[0024] The binder content in the active material-containing layer can be, for example, 0.5% by mass or more and 5% by mass or less.

[0025] Examples of conductive agents include carbon materials. Examples of carbon materials include acetylene black, carbon black, graphite, or mixtures thereof. There may be one or more types of conductive agents. In the active material-containing layer, the conductive agents may exist as particles. The shape of the conductive agent particles may be granular, fibrous, flaky, etc.

[0026] If the active material-containing layer contains a conductive agent, the content of the conductive agent can be, for example, 0.5% by mass or more and 30% by mass or less.

[0027] The intermediate layer includes a second fiber. The intermediate layer can improve the adhesion between the current collector and the active material-containing layer. It is desirable that the intermediate layer has a porous structure. It is desirable that the porous structure has a mesh structure. This makes it possible to achieve both the immobilization of the active material-containing layer and the current collector and electrical conductivity between the active material-containing layer and the current collector. An intermediate layer having a mesh structure can be made, for example, by forming a mesh of second fibers on the current collector using an electrospinning method. For the second fiber, a fiber with the same composition (resin, etc.) as described for the first fiber can be used.

[0028] The intermediate layer can be formed not only by electrospinning, but also by melt spinning and melt blowing.

[0029] The intermediate layer preferably contains a conductive material. This allows for good conductivity between the active material-containing layer and the current collector. Examples of conductive materials include carbon-based materials. Examples of carbon-based materials include acetylene black, carbon black, graphite, or mixtures thereof. There may be one or two types of conductive materials. The conductive material may be the same type as the conductive agent in the active material-containing layer, or it may be different.

[0030] By adjusting the type or content of the first fiber, the first fiber can be responsible for fixing the active material-containing layer and the current collector. In that case, the intermediate layer can be omitted.

[0031] The insulating layer includes an insulating third fiber. The insulating layer can function as a separator for electrically insulating the electrode from the counter electrode. The third fiber can be a fiber with the same composition (e.g., resin) as described for the first fiber. The insulating layer may cover the entire surface (plane parallel to the xy plane) of the active material-containing layer, or it may be formed on only a part of the surface. Furthermore, if an insulating film independent of the electrode is used as a separator, the insulating layer can be omitted.

[0032] The first, second, and third fibers may be of the same type or different types. Figures 1-3 show electrodes with a current collector structure in which an intermediate layer, an active material-containing layer, and an insulating layer are laminated, but the structure is not limited to this. It is also possible to interpose another layer between any of the layers. Furthermore, in Figures 1-3, boundaries are shown between adjacent layers to clearly distinguish between the intermediate layer, the active material-containing layer, and the insulating layer, but boundaries may not exist.

[0033] <Method for manufacturing an electrode according to the first embodiment> The method for manufacturing the electrode of the first embodiment will be described with reference to Figures 4-8.

[0034] (1st step) The powder containing active material particles, conductive agent particles, and a binder is dry-mixed.

[0035] An example of the first step is shown in Figure 4. First, the active material particles 10 and PTFE 11 are put into the stirrer 12. Conductive agent particles 13 are added to the stirrer 12 as needed. These raw material powders are dry-mixed in the stirrer 12. Next, the first fiber 14 is put into the stirrer 12, and these powders are dry-mixed in the stirrer 12. All raw material powders may be mixed at once, but it is preferable to dry-mix the active material particles 10, PTFE 11 and conductive agent particles 13 first, and then add the first fiber 14 and dry-mix again. Since the PTFE particles are aggregates of about 1 mm, it is preferable to mix the PTFE first and finely grind it. At that time, the PTFE may become slightly fibrous. By adding the first fiber after crushing the PTFE aggregates, it is possible to suppress the first fiber from becoming entangled with the PTFE. This makes it possible to uniformly disperse the PTFE and the first fiber.

[0036] (2nd process) A molded body is obtained by rolling a dry mixture obtained by dry mixing.

[0037] An example of the second step is shown in Figure 5. The powder film deposition apparatus includes a first roller 15, a second roller 16, and a guide roller 17. When the dry mixture 19 in the container 18 is supplied to the gap between the rotating first roller 15 and the second roller 16 which is fixed in a predetermined position, the dry mixture 19 is rolled in the feed direction 20 and processed into a strip-shaped or sheet-shaped molded body to obtain active material-containing layers 3a and 3b. This rolling process allows the PTFE in the dry mixture 19 to be fibrousized in the rolling direction (feed direction 20). The active material-containing layers 3a and 3b are transported to the next step by the guide roller 17. The active material-containing layers 3a and 3b are self-supporting films.

[0038] It is desirable to heat the surfaces of the first roller 15 and the second roller 16. This promotes the fibrillation of PTFE. It is desirable to heat to a temperature of 80°C or higher. This allows for the formation of many PTFE fibers, making it possible to form a strong, self-supporting film (molded body).

[0039] By increasing the rotation speed ratio of the first roller 15 to the second roller 16, a large shear force is applied to the self-supporting active material-containing layers 3a and 3b along the feed direction 20, making it easier for the PTFE fibers to stretch in the feed direction 20. As a result, the self-supporting layers (active material-containing layers 3a and 3b) can be rolled into a thin film. Furthermore, by increasing the roller rotation speed ratio, rolling occurs in the feed direction 20, but a certain degree of spreading also begins to occur in the width direction intersecting the feed direction 20, making the self-supporting layers (active material-containing layers 3a and 3b) more prone to tearing in the same feed direction 20 as the fiber direction. The first fiber contributes to suppressing or dispersing external forces in the width direction, thus suppressing tearing of the self-supporting layers (active material-containing layers 3a and 3b).

[0040] (3rd step) The resulting molded body (active material-containing layer) is supported on the current collector by heating and pressurizing.

[0041] An example of the third step is shown in Figure 6. The current collector may have an intermediate layer or not. In Figure 6, a current collector 2 with intermediate layers 4a and 4b is shown as a current collector with intermediate layers 21. The current collector with intermediate layers 21 is pre-wound into a roll. The press device includes a pair of rollers 22 and 23 and a guide roller 24.

[0042] The current collector 21 with an intermediate layer, which is wound into a roll, is unwound and transported along the transport direction 25 by the guide roller 24, and supplied to the gap between a pair of rollers 22 and 23 while keeping it along the surface of roller 22. The active material-containing layer 3a is also transported along the transport direction 25 and supplied to the gap between a pair of rollers 22 and 23 while keeping it along the surface of roller 23. Rollers 22 and 23 are heated by heaters. Heating and pressurizing are applied by sandwiching the active material-containing layer 3a and the current collector 21 with an intermediate layer between the heated rollers 22 and 23. This causes the active material-containing layer 3a to be supported on one of the intermediate layers of the current collector 21 with an intermediate layer.

[0043] Next, the active material-containing layer 3b is supported on the other intermediate layer of the current collector 21 with an intermediate layer by heating and pressurizing. The heating and pressurizing is performed by hot pressing with rollers, as described above. In this way, the active material-containing layers 3a and 3b are formed on both intermediate layers of the current collector 21 with an intermediate layer.

[0044] PTFE has a high melting point of 327°C and high heat resistance, so it contributes little to the immobilization of the active material-containing layer and the current collector. By making the melting point of the resin of the first fiber lower than that of PTFE, the active material-containing layer and the current collector can be immobilized by melting the first fiber. For example, if PVdF fibers are used as the first fiber, since the melting point of PVdF is 177°C, the PVdF fibers can be melted by setting the heating press temperature to around 180°C. This should be adjusted as appropriate depending on the type of first fiber. If there are multiple types of first fibers with different melting points, it is possible to melt only the first fibers with lower melting points to immobilize the active material-containing layer and the current collector, while the first fibers with higher melting points can act to maintain the layer shape (film shape).

[0045] (4th step) An insulating layer is formed on the active material-containing layer above the current collector.

[0046] The insulating layer is formed, for example, by electrospinning, melt spinning, or melt blowing.

[0047] An example of the fourth step is shown in Figure 7. Figure 7 shows an example of forming an insulating layer by electrospinning. An insulating layer 5a is formed by applying a raw material solution 28 from the nozzle 27 of the electrospinning apparatus to one of the active material-containing layers 3a. The raw material solution 28 is prepared, for example, by dissolving a resin (organic material) in an organic solvent. Examples of resins include those of the same type as those used to form the first fiber. Similarly, an insulating layer 5b is formed on the other active material-containing layer 3b by applying a raw material solution from the nozzle of the electrospinning apparatus to the other active material-containing layer 3b. The electrode 1 is thus manufactured. The manufactured electrode 1 is wound up as illustrated in Figure 8.

[0048] Note that the fourth step can be omitted.

[0049] The electrode manufacturing method of the embodiment may include steps other than the first to fourth steps. For example, a cutting step may be performed after the second step in order to give the molded body the desired shape.

[0050] <Example of the electrode according to the first embodiment> The example confirmed that the electrode of the first embodiment exhibits excellent film strength (shape retention of the active material-containing layer).

[0051] The positive electrode of Example 1 was manufactured by the method described in steps 1 through 3. The composition of the positive electrode active material-containing layer was as follows: 94 g of lithium nickel cobalt manganese oxide was used as the positive electrode active material particles. 3 g of acetylene black was used as the conductive agent. 2 g of polytetrafluoroethylene (PTFE) powder was used as the binder. In addition, 1 g of fibrous PVdF was used as the first fiber. The fibrous PVdF was formed by electrospinning. The average diameter of the fibrous PVdF was 0.5 μm. An aluminum foil with a thickness of 15 μm was used as the current collector.

[0052] When the active material-containing layer formed through the first and second steps was subjected to a strength test by pulling it in a direction intersecting the rolling direction (long side direction) (short side direction), it was confirmed that the direction of crack occurrence was dispersed, indicating that it possessed sufficient strength for practical use. However, when an active material-containing layer of the comparative example was prepared in the same manner as the example except that fibrous PVdF was not added, numerous cracks occurred in the rolling direction (long side direction).

[0053] Next, a mesh-like intermediate layer made of fibrous PVdF was formed on the aluminum foil current collector by electrospinning. The thickness of the intermediate layer was 3 μm.

[0054] Next, the positive electrode of Example 1 was fabricated by supporting an active material-containing layer on a current collector having intermediate layers formed on both sides, according to the third step.

[0055] When a peel test was conducted by attaching adhesive tape to the surface of the active material-containing layer of the fabricated positive electrode and then peeling it off, only the surface layer of the active material-containing layer peeled off, without peeling from the interface between the active material-containing layer and the current collector.

[0056] Furthermore, the active material-containing layer was prepared in the same manner as in Example 1, except that polyamide-imide was used instead of PVdF as the first fiber in the positive electrode active material-containing layer. The positive electrode of Example 2 was prepared in the same manner as in Example 1, except that the prepared active material-containing layer was used. Strength tests of the active material-containing layer and peel tests of the positive electrode were performed on the positive electrode of Example 2 in the same manner as in Example 1, and the same results as in Example 1 were obtained.

[0057] Furthermore, instead of positive electrode active material particles, Li4Ti5O 12 An active material-containing layer was prepared in the same manner as in Example 1, except that the negative electrode active material particles consisted of lithium titanate particles having a spinel structure represented by [the formula shown]. The negative electrode of Example 3 was then prepared using the prepared active material-containing layer. A strength test of the active material-containing layer and a peel test of the negative electrode were performed on the negative electrode of Example 3 in the same manner as in Example 1, and the same results as in Example 1 were obtained.

[0058] <Battery equipped with electrodes of the first embodiment> An example of using the electrodes of the first embodiment in a secondary battery will be described with reference to Figures 9-10. Examples of secondary batteries include non-aqueous electrolyte secondary batteries such as lithium secondary batteries. An example of a non-aqueous electrolyte secondary battery will be described in more detail with reference to the drawings.

[0059] Figure 9 is an exploded perspective view of an example of a non-aqueous electrolyte secondary battery according to an embodiment. The battery shown in Figure 9 is a sealed, rectangular non-aqueous electrolyte secondary battery. The non-aqueous electrolyte secondary battery 40 shown in Figure 9 comprises an outer casing 41, a lid 42, a positive electrode external terminal 43, a negative electrode external terminal 44, and an electrode group 45. The outer casing is composed of the outer casing 41 and the lid 42. The outer casing 41 has a bottomed rectangular tube shape and is made of a metal such as aluminum, aluminum alloy, iron, or stainless steel.

[0060] Figure 10 is a partially unfolded perspective view of an electrode group used in the non-aqueous electrolyte secondary battery shown in Figure 9. As shown in Figure 10, the flattened electrode group 45 has a positive electrode 46 and a negative electrode 47 wound in a flattened shape with a separator 48 between them. The positive electrode 46 includes a strip-shaped positive electrode current collector made of, for example, metal foil, a positive electrode current collector tab 46a that is one end parallel to the long side of the positive electrode current collector, and a positive electrode material layer (positive electrode active material containing layer) 46b formed on the positive electrode current collector, except for the portion of the positive electrode current collector tab 46a. On the other hand, the negative electrode 47 includes a strip-shaped negative electrode current collector made of, for example, metal foil, a negative electrode current collector tab 47a that is one end parallel to the long side of the negative electrode current collector, and a negative electrode material layer (negative electrode active material containing layer) 47b formed on the negative electrode current collector, except for the portion of the negative electrode current collector tab 47a. At least one of the positive electrode 46 or the negative electrode 47 can be the electrode of this embodiment. Furthermore, because a separator 48 is provided, it is not necessary to provide an insulating layer in the active material-containing layer of the electrode.

[0061] In this configuration, the positive electrode 46, separator 48, and negative electrode 47 are wound with their positions offset such that the positive electrode current collector tab 46a protrudes from the separator 48 in the direction of the winding axis of the electrode group, and the negative electrode current collector tab 47a protrudes from the separator 48 in the opposite direction. Due to this winding, as shown in Figure 10, the electrode group 45 has the positive electrode current collector tab 46a, which is wound in a spiral pattern, protruding from one end face, and the negative electrode current collector tab 47a, which is wound in a spiral pattern, protruding from the other end face. A non-aqueous electrolyte (not shown) is impregnated into the electrode group 45.

[0062] As shown in Figure 11, the positive electrode current collector tab 46a and the negative electrode current collector tab 47a are each divided into two bundles near the winding center of the electrode group. The conductive clamping member 49 has first and second clamping portions 49a and 49b that are roughly U-shaped, and a connecting portion 49c that electrically connects the first clamping portion 49a and the second clamping portion 49b. In each case, one bundle of the positive and negative electrode current collector tabs 46a and 47a is clamped by the first clamping portion 49a, and the other bundle is clamped by the second clamping portion 49b.

[0063] The positive lead 50 has a roughly rectangular support plate 50a, a through hole 50b opened in the support plate 50a, and strip-shaped current collectors 50c and 50d that branch out from the support plate 50a and extend downward. On the other hand, the negative lead 51 has a roughly rectangular support plate 51a, a through hole 51b opened in the support plate 51a, and strip-shaped current collectors 51c and 51d that branch out from the support plate 51a and extend downward.

[0064] The positive electrode lead 50 has a clamping member 49 sandwiched between the current collecting portions 50c and 50d. The current collecting portion 50c is positioned on the first clamping portion 49a of the clamping member 49. The current collecting portion 50d is positioned on the second clamping portion 49b. The current collecting portions 50c and 50d, the first and second clamping portions 49a and 49b, and the positive electrode current collecting tab 46a are joined together, for example, by ultrasonic welding. As a result, the positive electrode 46 of the electrode group 45 and the positive electrode lead 50 are electrically connected via the positive electrode current collecting tab 46a.

[0065] The negative electrode lead 51 has a clamping member 49 sandwiched between the current collecting portions 51c and 51d. The current collecting portion 51c is positioned on the first clamping portion 49a of the clamping member 49. On the other hand, the current collecting portion 51d is positioned on the second clamping portion 49b. The current collecting portions 51c and 51d, the first and second clamping portions 49a and 49b, and the negative electrode current collecting tab 47a are joined together, for example, by ultrasonic welding. As a result, the negative electrode 47 of the electrode group 45 and the negative electrode lead 51 are electrically connected via the negative electrode current collecting tab 47a.

[0066] The material of the positive and negative electrode leads 50, 51 and the clamping member 49 is not specifically designated, but it is desirable that they be made of the same material as the positive and negative electrode external terminals 3, 4. For example, aluminum or an aluminum alloy may be used for the positive electrode external terminal 43, and aluminum, an aluminum alloy, copper, nickel, or nickel-plated iron may be used for the negative electrode external terminal 44. For example, if the material of the external terminal is aluminum or an aluminum alloy, it is preferable that the material of the leads be aluminum or an aluminum alloy. Also, if the external terminal is copper, it is desirable that the material of the leads be copper or the like.

[0067] The rectangular plate-shaped lid 42 is seam-welded to the opening of the outer can 41, for example, by laser. The lid 42 is formed from a metal such as aluminum, aluminum alloy, iron, or stainless steel. It is preferable that the lid 42 and the outer can 41 be formed from the same type of metal. The positive external terminal 43 is electrically connected to the support plate 50a of the positive lead 50, and the negative external terminal 44 is electrically connected to the support plate 51a of the negative lead 51. An insulating gasket 52 is placed between the positive and negative external terminals 43, 44 and the lid 42, electrically insulating the positive and negative external terminals 43, 44 from the lid 42. It is preferable that the insulating gasket 52 is a molded resin product.

[0068] According to the electrode and its manufacturing method of the first embodiment described above, since the active material-containing layer is formed by rolling a molded body made by dry mixing a powder containing active material particles and a binder containing polytetrafluoroethylene and a first fiber body of a resin different from polytetrafluoroethylene, it is possible to suppress the tearing of the active material-containing layer in the rolling direction when force is applied in a direction intersecting the rolling direction (for example, the width direction). Therefore, high electrode strength can be obtained. In addition, the adhesion strength between the active material-containing layer and the current collector can be improved. As a result, when the electrodes are wound to create an electrode group using the electrode and counter electrode, it is possible to suppress the peeling of the active material-containing layer from the current collector.

[0069] <Ceramics of the second embodiment> An example of applying the structure of the embodiment to ceramics (sintered ceramic body) will be described.

[0070] The ceramic sintered body of the embodiment is manufactured, for example, by the following method. The raw material powder, which consists of main component particles made of solid powder of an inorganic material and a sintering aid, is pulverized to adjust the particle size. Silicon nitride particles can be used as an example of the solid powder of the inorganic material. Metal oxides can be used as an example of the sintering aid. Next, PTFE powder is added to the raw material powder as a binder, and then a dry mixture is prepared by dry mixing. Furthermore, a first fiber is added to the mixture, and then these are mixed to produce the raw material for ceramics. After that, the prepared ceramic raw material is formed by rolling to produce a molded body. The molded body may be shaped to a shape close to the product by cutting or other processes. The obtained molded body is sintered at a high temperature of 1000°C or higher. During the sintering process, the particles fuse together to obtain a ceramic sintered body.

[0071] According to the embodiment of the ceramic sintered body, it is possible to suppress the occurrence of cracks along the rolling direction when a force is applied in a direction different from the rolling direction. Therefore, it is possible to improve the strength of the ceramic sintered body.

[0072] <Fuel cell of the third embodiment> An example of applying the structure of the embodiment to a fuel cell will be described.

[0073] The fuel cell of this embodiment is manufactured, for example, by the following method: A carbon dispersion is prepared by adding a carbon material to a solution of a fluororesin material and mixing them. The carbon dispersion is applied to an electrolyte membrane by electrospinning to form a membrane containing water-repellent fibrous carbon as a gas diffusion layer. A dry mixture is prepared by adding PTFE powder to catalyst and conductive auxiliary powders and dry mixing them. A catalyst mixture powder is then prepared by adding fibrous material such as an electrolyte polymer to the mixture and dry mixing it further. The prepared catalyst mixture powder is then rolled to form a sheet to obtain a catalyst layer. The catalyst layer is bonded to the carbon membrane formed on the electrolyte membrane to produce a fuel cell electrode assembly comprising a catalyst layer, a gas diffusion layer, and an electrolyte membrane.

[0074] According to the embodiment of the fuel cell electrode assembly, it is possible to suppress the occurrence of cracks along the rolling direction when a force is applied to the catalyst layer in a direction different from the rolling direction. Therefore, it is possible to realize a fuel cell equipped with a fuel cell electrode assembly having high strength.

[0075] The structure of the embodiment described above includes a molded body formed by rolling a dry-mixed powder containing particles and a binder containing polytetrafluoroethylene and a first fiber body of a resin different from polytetrafluoroethylene. The molded body can suppress damage such as cracking in a specific direction such as the rolling direction, thereby improving the strength of the molded body. Therefore, it is possible to provide a highly practical structure that can be applied to a wide range of fields such as electrodes, ceramic sintered bodies, and fuel cells.

[0076] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0077] 1... Electrode (structure), 2... Current collector, 3a... Active material-containing layer, 3b... Active material-containing layer, 4a... Intermediate layer, 4b... Intermediate layer, 5a... Insulating layer, 5b... Insulating layer, 6... Current collector tab, 10... Active material particles, 12... Agitator, 13... Conductive particles, 14... First fiber body, 15... First roller, 16... Second roller, 17... Guide roller, 18... Container, 19... Dry mixture, 20... Feeding direction, 21... Current collector with intermediate layer, 22, 23... Rollers, 24... Guide roller, 25, 26... Conveying direction, 27... Nozzle section, 28... Raw material solution, 40... Non-aqueous electrolyte secondary battery, 41... Outer Container, 42...Lid, 43...Positive electrode external terminal, 44...Negative electrode external terminal, 45...Electrode group, 46...Positive electrode, 46a...Positive electrode current collector tab, 46b...Positive electrode material layer (positive electrode active material containing layer), 47...Negative electrode, 47a...Negative electrode current collector tab, 47b...Negative electrode material layer (negative electrode active material containing layer), 48...Separator, 49...Clamping member, 49a...First clamping part, 49b...Second clamping part, 49c...Connecting part, 50...Positive electrode lead, 50a...Support plate, 50b...Through hole, 50c, 50d...Current collector part, 51...Negative electrode lead, 51a...Support plate, 51b...Through hole, 51c, 51d...Current collector part, 52...Insulating gasket.

Claims

1. A structure comprising a molded body formed by rolling a dry mixture of powders containing particles and a binder containing polytetrafluoroethylene and a first fiber body of a resin different from the polytetrafluoroethylene.

2. The structure according to claim 1, wherein the first fiber body includes at least one of a plurality of fiber bodies with different average diameters or a plurality of fiber bodies with different melting temperatures.

3. The structure according to claim 1, wherein the resin of the first fiber, which is different from the polytetrafluoroethylene, comprises at least one selected from the group consisting of polyimide, polyamide, polyamideimide, polyvinylidene fluoride, cellulose, polyolefin, polyether, polyetherimide, polyketone, polysulfone, polyethersulfone, polymethacrylic acid, polyvinyl alcohol, polyvinyl acetal, and copolymer of isobutylene and maleic anhydride.

4. The structure according to claim 1, further comprising a base material on which the molded body is supported.

5. The structure according to claim 4, further comprising an intermediate layer disposed between the molded body and the substrate, and including a second fiber body.

6. The structure described in claim 4 or 5 is an electrode.

7. The structure according to claim 5, wherein the intermediate layer further comprises a conductive material including a carbon-based material.

8. The structure according to claim 1, further comprising a third fibrous body having insulating properties, provided on at least a portion of the surface of the molded body.

9. Dry mixing of particles and a binder containing polytetrafluoroethylene and a first fiber body of a resin different from the polytetrafluoroethylene, The dry mixture obtained by the dry mixing is formed by rolling. A method for manufacturing a structure, including [the specified element].

10. A method for manufacturing an electrode as a structure according to claim 9, further comprising supporting the molded body obtained by the molding process onto a substrate by heating and pressurizing.

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