WO2005108647A1

WO2005108647A1 - Porous metal foil with carrier foil and process for producing the same

Info

Publication number: WO2005108647A1
Application number: PCT/JP2005/008195
Authority: WO
Inventors: Yoshiki Sakaguchi; Hitohiko Honda; Kiyotaka Yasuda
Original assignee: Mitsui Mining & Smelting Co., Ltd.
Priority date: 2004-05-06
Filing date: 2005-04-28
Publication date: 2005-11-17
Also published as: JP2005320562A; JP4298578B2

Abstract

A porous metal foil with carrier foil characterized by having a porous metal foil layer disposed by electroplating on a conductive carrier foil and further having interposed therebetween a junction interface layer of conductive polymer. The conductive polymer is preferably a lithium-ion-conducting polymer. Further, a fluorinated conductive polymer is preferred. Especially, a polyvinylidene fluoride is preferred. Preferably, the carrier foil is an electrolytic foil, and with respect to surfaces of the carrier foil, one in contact with the junction interface layer is a deposition surface at the production of the electrolytic foil.

Description

Specification

Porous metal foil with carrier foil and method for producing the same

Technical field

The present invention relates to a porous metal foil with a carrier foil and a method for producing the same. The present invention also relates to a method for producing a negative electrode for a non-aqueous electrolyte secondary battery.

Background art

[0002] Porous metal foils are widely used, for example, as current collectors for batteries and as carriers for catalysts.

The method for producing this kind of porous metal foil includes, for example, (a) forming an insulating film of a desired shape on the electrode surface and applying electrolytic plating thereon, so that a portion corresponding to the film is applied to the electrode; A method for producing a porous metal foil in such a way that prayer does not occur, (b) a method for sintering a fibrous or granular metal into a porous sintered body, and (c) a method for producing a metal by rolling or electrolytic plating. After the foil is manufactured, there is a method of punching and punching holes.

[0003] Among these various methods, as a method for producing a porous metal foil by electrolytic plating, for example, a metal substrate to be electrodeposited is roughened by sandblasting, chemical etching, electrolytic etching, machining, or the like. Roughly spray the insulating paint on the rough surface, or provide an insulating coating or oxide film on the entire surface, and remove the coating such as wire brush and puff partially and incompletely. A method of producing a metal foil by applying electrolytic plating later is known (see Patent Document 1). By peeling the obtained metal foil from the substrate, a porous body can be obtained.

[0004] Alternatively, the electrode plate surface is subjected to hydrophobic treatment by adsorption of a carboxylic acid having a hydrophobic group, coupling using a higher alcohol salt and a metal, or coating of fluorinated titanium, and the like. A method of producing a metal foil by performing electrolytic plating is known (see Patent Document 2). In this method, hydrogen bubbles generated on the electrode plate surface during electroplating remain on the electrode plate surface, so that contact with the electrolyte becomes insufficient and electrodeposition does not occur at that portion. We are using.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 50-141540

Patent Document 2: JP-A-5-23760 [0006] With any of the above techniques, the metal foil obtained thereby is porous, but it is not easy to increase the strength. Also, it is not easy to improve the efficiency of electrodeposition by applying an insulating substance to the electrode surface. Furthermore, in the technique described in Patent Document 1, it is essential to roughen the electrode surface, and therefore, a roughening treatment of the electrode is required prior to electroplating, which complicates the manufacturing process. In addition, since the metal foil is thin and stiff, it is not easy to handle and process it alone.

Disclosure of the invention

[0007] Accordingly, an object of the present invention is to provide a porous metal foil and a method for producing the same, which can solve the above-mentioned various disadvantages of the related art.

[0008] The present invention has a porous metal foil layer formed by electrolytic plating on a conductive carrier foil, and further includes a bonding interface layer formed between the two by using a conductive polymer. The object has been achieved by providing a porous metal foil with a carrier foil, characterized in that the metal foil has a carrier foil.

[0009] The present invention is also a method for producing the porous metal foil with a carrier foil,

A method for producing a porous metal foil with a carrier foil, comprising applying a coating liquid containing the conductive polymer to one surface of the carrier foil, and forming the metal foil thereon by electrolysis. To provide.

[0010] Further, the present invention is obtained by peeling the porous metal foil from the porous metal foil with a carrier foil, and the conductive polymer is attached to one surface of the porous metal foil layer. The present invention provides a porous metal foil characterized by the following. Further, the negative electrode for a non-aqueous electrolyte secondary battery, comprising the porous metal foil with a carrier foil, and a porous metal foil obtained by peeling the porous metal foil. It is intended to provide a non-aqueous electrolyte secondary battery comprising a negative electrode.

Further, the present invention includes a pair of current collecting surface layers whose surfaces are in contact with the electrolytic solution, and an active material layer containing active material particles having a high ability to form a lithium compound interposed between the surface layers. A method for producing a negative electrode for a non-aqueous electrolyte secondary battery,

A coating solution containing a conductive polymer is applied to one surface of the carrier foil, and a metal material having a low ability to form a lithium compound is electroplated thereon to form one current-collecting surface layer. A conductive slurry containing particles of an active material is applied on the surface layer for power application to form an active material layer, and a metal material having a low ability to form a lithium compound is electrolytically deposited on the active material layer to form an active material layer. Forming a current collecting surface layer, and then separating and separating the carrier foil from the one current collecting surface layer, a method for producing a negative electrode for a non-aqueous electrolyte secondary battery, To provide.

Brief Description of Drawings

[FIG. 1] FIGS. 1 (a) to 1 (d) are process diagrams showing a method for producing a porous metal foil of the present invention.

FIG. 2 is a schematic diagram showing a structure of a negative electrode for a non-aqueous electrolyte secondary battery provided with the metal foil of the present invention.

FIG. 3 (a) and FIG. 3 (b) are diagrams showing charging characteristics of the negative electrode obtained in Example 1.

FIG. 4 (a) and FIG. 4 (b) are diagrams showing charging characteristics of the negative electrode obtained in Comparative Example 1.

FIG. 5 is a scanning electron micrograph of the surface state of the first metal foil in the negative electrode obtained in Example 2.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described based on preferred embodiments. First, the porous metal foil with a carrier foil of the present invention will be described. The porous metal foil with a carrier foil of the present embodiment has a three-layer structure having a porous metal foil layer on the carrier foil and a bonding interface layer between the two. The bonding interface layer is in direct contact with each of the carrier foil and the porous metal foil layer (hereinafter simply referred to as metal foil or porous metal foil).

[0014] The metal foil is formed by electrolytic plating. The metal foil is porous with many micropores. The metal foil has both a fine hole penetrating the metal foil in the thickness direction and a fine hole closing in the middle. Of these, the micropores referred to in the present invention mean micropores penetrating the metal foil in the thickness direction. However, this does not exclude a metal foil having micropores closed in the present invention. Also, it does not mean that such a metal foil is preferable.

[0015] The thickness of the metal foil is not particularly limited, and an appropriate thickness is selected depending on the specific use. For example, it is used as an electrode material for a non-aqueous electrolyte secondary battery shown in FIG. From the viewpoint of securing mechanical strength, easy formation of micropores, improvement of energy density, smooth distribution of non-aqueous electrolyte, etc., preferably 1 to: LOO / zm, more preferably The thickness is 2 to 20 μm, more preferably 3 to 10 μm.

[0016] The metal foil can be composed of various metal materials. For example, a metal foil containing at least one metal of Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag and Au can be used. That is, it is possible to constitute a simple substance of these metals, an alloy of two or more of these metals, or a metal foil containing other elements in addition to them. When metal foil is used as the electrode material of the non-aqueous electrolyte secondary battery shown in Fig. 2 described below, Cu, Ni, Co, Fe, Cr, and Au force must also be composed. Low reactivity with lithium Force is also preferred.

[0017] The carrier foil is used as a support for producing a porous metal foil.

Further, the produced porous metal foil is supported before use or during processing, and is used to improve the handleability of the metal foil. From these viewpoints, the carrier foil has such a strength that no swelling or the like occurs in the manufacturing process of the metal foil and in the processing and transporting processes after the manufacturing! /, Prefer to,. Therefore, the carrier foil preferably has a thickness of about 10 to 50 μm.

[0018] In view of the manufacturing method described later, a conductive foil is used as the carrier foil. In this case, the carrier foil need not be made of metal as long as it has conductivity. However, using a metal carrier foil has the advantage that the carrier foil can be melted and made and recycled after the production of the porous metal foil. When using a metal carrier foil, the carrier foil is composed of at least one metal selected from the group consisting of Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, Au, Al and Ti. , Prefer to,.

As the carrier foil, for example, foils manufactured by various methods such as a rolled foil and an electrolytic foil can be used without any particular limitation. Unlike the conventional method for manufacturing a porous metal foil, the present invention does not necessarily require that the surface of the carrier foil is roughened. However, it is preferable that the surface of the carrier foil has a certain degree of unevenness from the viewpoint of controlling the pore diameter ゃ existence density of the fine pores. Each surface of the rolled foil is smooth due to the manufacturing method. On the other hand, the electrolytic foil has a rough surface on one side and a smooth surface on the other side. The rough surface is a deposition surface when producing an electrolytic foil. Therefore, the rough surface of the electrolytic foil If is used as an electrodeposition surface, the labor for separately performing a roughening treatment on the carrier foil can be omitted, which is convenient. When using a roughened surface as an electrodeposited surface, its surface roughness Ra should be 0.05 to 5 m, particularly 0.2 to 0.8 / zm, and should have a desired diameter and existing density. It is preferable because holes can be easily formed.

[0020] Between the carrier foil and the porous metal foil, a bonding interface layer of both foils is interposed. The bonding interface layer is formed by applying and drying a coating solution containing a conductive polymer. The bonding interface layer is used for forming desired micropores in the metal foil and for imparting desired strength and flexibility to the metal foil after peeling from the carrier foil. When the carrier foil is an electrolytic foil, it is preferable that, of the surface of the carrier foil, a surface in contact with a bonding interface is a deposition surface when the electrolytic foil is manufactured.

[0021] As the conductive polymer constituting the bonding interface layer, a conventionally known polymer whose type is not particularly limited can be used. For example, polypyridene-fluoride (PVDf), polyethylene oxide (PEO), polyacryl-tolyl (PAN), polymethyl methacrylate (PMMA) and the like can be mentioned. In particular, when a porous metal foil is used as a negative electrode material for a non-aqueous electrolyte secondary battery, a lithium ion conductive polymer is preferably used as the conductive polymer. Further, the conductive polymer which is not related to the specific use of the porous metal foil is preferably a fluorine-containing conductive polymer. This is because the fluorine-containing polymer has high thermal and chemical stability and excellent mechanical strength. Considering these facts, it is particularly preferable to use poly (pyridene fluoride), which is a fluorine-containing polymer having lithium ion conductivity.

[0022] The bonding interface layer formed using the conductive polymer may be present continuously over the entire area between the carrier foil and the porous metal foil with a thickness sufficient to completely separate the carrier foil and the porous metal foil. . Or it may exist discontinuously between both foils. The amount of the conductive polymer in the bonding interface layer is determined from the viewpoint of forming desired micropores in the porous metal foil and imparting desired strength and flexibility to the porous metal foil after peeling from the carrier foil. The appropriate amount is determined.

[0023] In the porous metal foil with a carrier foil of the present embodiment, the metal foil may be peeled off the carrier foil after a predetermined application to the metal foil is completed. Or for metal foil The metal foil and carrier foil may be peeled off immediately before performing the predetermined processing. As a result, the thickness is thin and the stiffness is weak, and the handling and properties of the metal foil are remarkably improved.

The porous metal foil with the carrier foil of the present embodiment has a peeled porous metal foil on one surface of which a conductive polymer derived from a bonding interface layer is adhered. This adhesion imparts the desired strength and flexibility to the metal foil. The conductive polymer may be continuously coated over the entire surface of the porous metal foil, or may be discontinuously coated in an island shape. According to the study of the present inventors, it has been found that the strength and flexibility of the metal foil can be improved only by the conductive polymer covering one surface of the porous metal foil discontinuously in an island shape. Particularly noteworthy is that even when the pores of the porous metal foil are closed with a conductive polymer, when the metal foil is used as a negative electrode material for a non-aqueous electrolyte secondary battery, the lithium ion conductivity is reduced. Expression.

Next, a method for producing a metal foil with a carrier foil according to the present invention will be described with reference to FIGS. 1 (a) and 1 (d). First, a carrier foil 1 is prepared as shown in FIG. When the carrier foil 1 is also an electrolytic foil, as shown in the figure, the carrier foil 1 has a rough surface la on one side and a smooth surface lb on the other side. Of these surfaces, it is preferable to use the rough surface la as the electrodeposition surface for the reason described above.

Next, a release agent is applied to one surface of the carrier foil 1 to perform a release treatment. For the reasons described above, the release agent is preferably applied to the rough surface la of the carrier foil 1. The release agent is used to successfully release the metal foil from the carrier foil 1 in a release step described later. The peeling treatment is performed by, for example, a chrome plating treatment, a nickel plating treatment, a lead plating treatment, a chromate treatment, or the like. Further, a release treatment using a release agent made of an organic compound can also be performed. As the organic compound, it is particularly preferable to use a nitrogen-containing compound or a sulfur-containing compound. Examples of nitrogen-containing conjugates include benzotriazole (BTA), carboxybenzotriazole (CBTA), tolyltriazole (ΤΤΑ), Ν ′, N′-bis (benzotriazolylmethyl) urea (BTD-U) And triazole-based compounds such as 3-amino-1H-1,2,4-triazole (Α). Examples of the sulfur-containing compound include mercaptobenzothiazole (ΜΒΤ), thiocyanuric acid (TCA), and 2-benzimidazolthiol (BIT). The releasability depends on the concentration of the release agent and the amount applied. Can control. The step of applying the release agent is performed only in order to successfully release the metal foil from the carrier foil 1 in the release step described below. Therefore, even if this step is omitted, a metal foil having fine holes can be formed.

Next, as shown in FIG. 1 (b), after a release agent (not shown) is applied, a coating liquid containing a conductive polymer is applied and dried to form a coating film 2. Alternatively, after applying the coating liquid, the surface to which the coating liquid is applied may be subjected to a release treatment with a release agent. The coating liquid is formed by dissolving a conductive polymer in a volatile organic solvent. When, for example, polyvinylidene fluoride is used as the conductive polymer, N-methylpyrrolidinone can be used as the organic solvent. As shown in FIG. 1 (b), the coating liquid is applied to the rough surface la of the carrier foil 1, so that it is likely to accumulate in the concave portions on the rough surface la. If the solvent evaporates in this state, the thickness of the coating film 2 becomes uneven. That is, the thickness of the coating film corresponding to the concave portion of the rough surface is large, and the thickness of the coating film corresponding to the convex portion is small. In the present invention, a large number of fine holes are formed as shown in FIG. 1 (c) by utilizing the unevenness of the thickness of the coating film 2.

[0028] In the present invention, the mechanism by which the porous metal foil is formed on the carrier foil 1 is considered as follows. The carrier foil 1 on which the coating film 2 is formed is subjected to an electrolytic plating process, and a metal foil 3 is formed on the coating film 2 as shown in FIG. The conductive polymer that forms the coating has electronic conductivity, though not as much as metal. Therefore, the coating 2 has different electron conductivity depending on its thickness. As a result, when a metal is deposited by electroplating on the coating film 2 containing the conductive polymer, a difference occurs in the deposition rate depending on the electron conductivity, and the difference in the deposition rate causes the metal foil 3 to be deposited on the metal foil 3. Micropores 4 are formed. In other words, the portion where the electrodeposition rate is low, in other words, the thickness of the coating film 2 and the portion tend to become the micropores 4.

[0029] As described above, it is possible to control the pore diameter ゃ existence density by the surface roughness Ra of the rough surface la as described above. In addition to this force, the fineness can also be controlled by the concentration of the conductive polymer contained in the coating liquid. The pore diameter of hole 4 divided by the existing density can be controlled. For example, when the concentration of the conductive polymer is low, the pore size tends to decrease, and the existing density also tends to decrease. Conversely, when the concentration of the conductive polymer is high, the pore size tends to increase.

[0030] The concentration of the conductive polymer in the coating liquid is not only a dominant factor of the pore diameter of the micropores / existence density, but also a dominant factor of the strength and flexibility of the obtained metal foil. Also. For example, as the concentration of the conductive polymer increases, the strength / flexibility of the obtained metal foil tends to increase. From these various viewpoints, the concentration of the conductive polymer in the coating liquid is preferably 0.05 to 5% by weight, particularly preferably 1 to 3% by weight.

In FIG. 1C, the fine holes 4 are drawn so as to correspond to the thick portions of the coating film 2. However, this is only for the purpose of explaining the mechanism of the formation of the fine holes 4 in the manufacturing method of the present invention, and the fine holes 4 are not necessarily formed corresponding to the thick portion of the coating film 2. Not necessarily. The plating bath and the plating conditions for forming the metal foil 3 are appropriately selected according to the constituent material of the metal foil. For example, when the metal foil 3 is composed of N, a Watt bath or a sulfamic acid bath having the following composition can be used as a plating bath. When these plating baths are used, the bath temperature is preferably about 40 to 70 ° C, and the current density is preferably about 0.5 to ²⁰ AZdm2!

NiSO6Η O 150 ~ 300gZl

• N

• H

If the metal foil 3 is manufactured by the above-described method, it is easy to freely control the hole diameter ゃ existing density of the fine holes 4. In addition, it is easy to freely control the strength and flexibility of the metal foil. In the present invention, the metal foil is always deposited on a new surface, that is, on the surface of the carrier foil which is replaced at each production. As a result, the state of the surface can always be kept constant, so that it is possible to precisely control the pore diameter / existence density, strength and flexibility. In the conventional method for producing an electrolytic foil, the surface on which the metal foil is electrodeposited is always the same surface, that is, the peripheral surface of the drum force sword body, so that the state of the surface changes with time.

[0033] The metal foil 3 obtained in this manner has a force depending on manufacturing conditions, preferably 0.01 to 200.

/ zm, more preferably 0.05 to 50 / ζπι, and still more preferably 0.1 to 10 / zm. When the metal foil 3 having the micropores 4 in this range is used, for example, as a material for an electrode of a nonaqueous electrolyte secondary battery shown in FIG. 2 described later, the flow of the nonaqueous electrolyte can be maintained while maintaining the strength of the metal foil 3. Can be sufficiently secured. Further, it is possible to effectively prevent the active material from falling off due to the absorption and desorption of lithium. The [0034] For similar reasons, 5 micropores 4 having the above diameter, connexion and the site of the metal foil 3 throat Mitechi, in an area of 1cm ^2: LOOOO pieces, in particular 500 to 8000 pieces, especially 1000 It is preferred to be present at a density of ~ 6000. The method for measuring the pore diameter ゃ existing density of the micropores 4 will be described in Examples described later.

[0035] The metal foil in the porous metal foil with a carrier foil obtained by the above method is subjected to a desired process in a state of being adhered to the carrier foil. In some cases, as shown in FIG. 1 (d), the metal foil 3 may be peeled off from the carrier foil 1 and subjected to desired processing. The metal foil thus obtained is used, for example, as a material for an electrode of a battery, a carrier for a catalyst in various chemical reactions, and a filter for gas or liquid. In particular, it is suitably used as a material for electrodes for non-aqueous electrolyte secondary batteries, particularly as a material for negative electrodes. FIG. 2 schematically shows the structure of a negative electrode 6 for a non-aqueous electrolyte secondary battery including a metal foil obtained by peeling from a porous metal foil with a carrier foil manufactured according to the present invention. ing. The negative electrode 6 is configured such that an active material layer 5 containing particles 7 of a negative electrode active material is sandwiched between a pair of metal foils 3a and 3b. Many fine holes are formed in each of the metal foils 3a and 3b. The method for forming the fine holes will be described later. According to the negative electrode 6, the flow path of the electrolyte is sufficiently ensured through the many fine holes formed in the metal foils 3 a and 3 b, so that the capacity of the nonaqueous electrolyte secondary battery is increased. In a conventional negative electrode having a thick-film current collector, it was impossible to supply an electrolytic solution to the active material layer through the current collector. Therefore, when it was desired to use both surfaces of the negative electrode for the electrode reaction, it was necessary to form an active material layer on each surface of the current collector. On the other hand, the negative electrode 6 shown in FIG. 2 has an advantage that the active material layer needs to be formed only on one surface of the metal foil. This also contributes to the improvement of the energy density described later.

In the negative electrode 6 shown in FIG. 2, it is preferable that the material forming the metal foils 3a and 3b penetrates over the entire area of the active material layer 5 in the thickness direction. It is preferable that the active material particles 7 exist in the permeated material. As a result, the adhesion between the active material layer 5 and the metal foils 3a and 3b becomes strong, and the active material is further prevented from falling off. In addition, since the conductive material is ensured between the metal foils 3a and 3b and the active material through the material penetrated into the active material layer 5, an electrically isolated active material is generated. The generation of an electrically isolated active material deep in the layer 5 is effectively prevented, and the current collecting function is maintained. as a result In addition, a decrease in the function as the negative electrode is suppressed. Further, the life of the negative electrode can be prolonged. This is particularly advantageous when a material such as a silicon-based material, which is a semiconductor and has poor electron conductivity, is used as the active material.

It is preferable that the material constituting the metal foils 3a and 3b existing in the active material layer 5 penetrates the active material layer 5 in the thickness direction. As a result, the metal foils 3a and 3b are electrically conducted through the material, and the electron conductivity of the entire negative electrode 6 is further increased. That is, the negative electrode 6 has a current collecting function as a whole of the negative electrode. The fact that the material constituting the metal foils 3a and 3b penetrates over the entire area in the thickness direction of the active material layer 5 and the two metal foils are connected to each other can be determined by electron microscope mapping using the material as a measurement target. . Furthermore, when a material constituting the metal foils 3a, 3b enters at least a part of the fine holes in at least one of the metal foils 3a, 3b (the metal foil 3a in FIG. 2), the active material is activated by the anchor effect. This is preferable because the adhesion between the layer 5 and the metal foil becomes strong. In this case, it is preferable that the material constituting the metal foils 3a and 3b enter the micropores so as not to completely fill the micropores, from the viewpoint of ensuring the flow of the electrolytic solution. A preferred method for permeating the material constituting the metal foils 3a and 3b into the active material layer will be described later.

Further, in the negative electrode 6 shown in FIG. 2, the active material layer 5 is sandwiched between the pair of metal foils 3a and 3b, so that particles of the active material are absorbed and desorbed by lithium. Even after repeated expansion and contraction, it is difficult to fall off the negative electrode 2. Further, the adhesion between the active material layer 5 and the metal foils 3a and 3b is improved by the above-described anchor effect. As a result, the cycle characteristics are improved. Since the metal foils 3a and 3b have a small thickness, the energy density per unit volume and unit weight can be increased.

As the negative electrode active material, for example, particles of an alloy containing Si or Sn, which are high-capacity active materials, are preferably used. The average particle diameter D of the active material particles is 0.1 to 30 / ζπι, which is preferable.

50

Or 0.5 to 5 / ζπι. The active material layer 5 containing such active material particles has a thickness of 10 to 80 μm, preferably 20 to 50 μm. By doing so, the capacity and the energy density of the battery can be increased.

The negative electrode 6 shown in FIG. 2 can be manufactured by using the above-described method for manufacturing a porous metal foil with a carrier foil. For example, first carry out the method shown in Fig. 1 (a) to 1 (c). A porous metal foil with a metal foil is manufactured. This is used as one metal foil 3a. Next, the active material layer 5 is formed on the metal foil 3a in a state where the metal foil 3a is not peeled off by the carrier foil force. The active material layer 5 is formed by applying a paste containing, for example, particles of an active material or particles of a conductive material.

[0041] On the active material layer 5, a carbonaceous material (for example, acetylene bran) having an average particle diameter D

50

H) is applied in a thickness of 0.001 to m. This operation is for forming a large number of fine holes in the other metal foil 3b. On top of that, the constituent material of the metal foil is electrodeposited by electrolysis to form the other metal foil 3b. In this case, the plating solution penetrates into the active material layer 5 and reaches the interface between the active material layer 5 and the metal foil 3a, under which the electrolytic plating is performed. As a result, (a) the inside of the active material layer 5, (mouth) the outer surface side of the active material layer 5 (that is, the surface in contact with the plating liquid, and (c) the inner surface side of the active material layer 5 (that is, the metal) The metal material is deposited on the surface facing the foil 3a). As a result, the metal foil 3b is formed, and the material constituting the metal foil 3b penetrates the entire active material layer 5 in the thickness direction to reach the metal foil 3a. Part of it enters a part of the fine hole of the metal foil 3a. Finally, the metal foil 3a manufactured first is also peeled off the carrier foil. Thereby, the negative electrode 6 shown in FIG. 2 is obtained. The negative electrode 6 thus obtained has substantially the same electrode characteristics on each surface. That is, each of the metal foils 3a and 3b has substantially the same size and the same density of micropores.

[0042] In the negative electrode 6 thus obtained, the conductive polymer is adhered to the outer surface of the metal foil 3a. The negative electrode 6 is used together with a known positive electrode, a separator, and a non-aqueous electrolyte to form a non-aqueous electrolyte secondary battery. The positive electrode is prepared by suspending a positive electrode active material and, if necessary, a conductive agent and a binder in an appropriate solvent to prepare a positive electrode mixture, applying the mixture to a current collector, drying the mixture, rolling, pressing, and Obtained by cutting and punching. As the positive electrode active material, a conventionally known positive electrode active material such as a lithium nickel composite oxide, a lithium manganese composite oxide, a lithium cobalt composite oxide, and the like are used. As the separator, a synthetic resin nonwoven fabric, a polyethylene or polypropylene porous film, or the like is preferably used. In the case of a lithium secondary battery, the non-aqueous electrolyte is a solution in which a lithium salt as a supporting electrolyte is dissolved in an organic solvent. Examples of lithium salts include LiCIO, Li A1C1, LiPF, LiAsF, LiSbF, LiSCN, LiCl, LiBr ゝ Lil, LiCF SO, LiC F

4 6 6 6 3 3 4 9

SO etc. are illustrated.

Three

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited to the working examples.

Example 1

The copper carrier foil (thickness: 35 μm) obtained by the electrolysis was acid-washed at room temperature for 30 seconds. Subsequently, pure water washing was performed at room temperature for 30 seconds. Next, the carrier foil was immersed in a 3.5 g Zl CBTA solution kept at 40 ° C for 30 seconds. Thereby, a peeling treatment was performed. After the peeling treatment, the solution strength was also raised, and the substrate was washed with pure water for 15 seconds.

[0045] A coating solution having a concentration of 2.5% by weight in which polyvinylidene fluoride was dissolved in N-methyl virolidinone was applied to a rough surface (surface roughness Ra = 0.5 ^ m) of the carrier foil. After the solvent was volatilized and the coating film was formed, the carrier foil was immersed in a Watt bath having the following bath composition to perform electroplating. Thereby, a first metal foil having a nickel strength was formed on the coating film. The current density was 5 AZdm ² , the bath temperature was 50 ° C, and the pH was 5. A nickel electrode was used for the anode. The power supply used was a DC power supply. The metal foil was formed to a thickness of 5 m. After lifting from the plating bath, the substrate was washed with pure water for 30 seconds and dried in the air. Thus, a porous metal foil with a carrier foil was obtained.

Next, a slurry containing particles of the negative electrode active material was applied on a metal foil so as to have a film thickness to form an active material layer. The active material particles were an alloy with a composition of Si80wt% -Ni20wt%, and the average particle size was D = 1.5 m. The composition of the slurry is as follows: active material: Ni powder: a

50

Cethylene black: polyvinylidene fluoride = 60: 34: 1: 5.

[0047] On the active material layer, a carbonaceous material (acetylene black) having an average particle diameter D force of S40 nm is included.

50

One coat was applied to a thickness of 0.5 m. Subsequently, electrolytic plating was performed on this coating film under the same electrolytic conditions as described above to form a second metal foil having a nickel strength. Metal foil Was formed to a thickness of 3 μm.

[0048] Finally, the first metal foil and the carrier foil were peeled off to obtain a negative electrode for a non-aqueous electrolyte secondary battery in which an active material layer was sandwiched between a pair of metal foils. As a result of qualitative analysis by NMR and IR, it was confirmed that the negative electrode had polyvinylidene fluoride adhered to the outer surface of the first metal foil.

Example 2

Instead of the watt bath used in Example 1, an H 2 SO 3 / CuSO-based plating bath was used.

2 4 4

First and second metal foils having copper strength were formed. The composition of the plating bath is CuSO power ¾50gZl

Four

The H SO was 70 gZl. Current density was 5AZdm ^2. Other than this, the same as in Example 1

twenty four

Thus, a negative electrode for a non-aqueous electrolyte secondary battery was obtained.

[Comparative Example 1]

The copper carrier foil (thickness: 35 μm) obtained by the electrolysis was acid-washed at room temperature for 30 seconds. Subsequently, pure water washing was performed at room temperature for 30 seconds. Next, the carrier foil was subjected to a peeling treatment in the same manner as in Example 1. Next, the carrier foil was immersed in a watt bath having the same bath composition as in Example 1 to perform electroplating to form a first metal foil made of nickel color. The electrolysis conditions were the same as in Example 1. A slurry containing particles of the negative electrode active material was applied on the first metal foil to a thickness of 15 / zm to form an active material layer. The same active material and slurry as in Example 1 were used. Electrolytic plating was performed on the active material layer under the same conditions as in Example 1 to form a second metal foil made of nickel copper. The metal foil was formed to a thickness of 3 m. Finally, the first metal foil and the carrier foil were peeled off to obtain a negative electrode for a non-aqueous electrolyte secondary battery in which an active material layer was sandwiched between a pair of metal foils.

[Performance evaluation]

The charging characteristics of the negative electrodes obtained in Example 1 and Comparative Example 1 were evaluated by the following methods. The results are shown in FIGS. 3 (a) and (b) and FIGS. 4 (a) and (b). Figures 3 (a) and 4 (a) show the charging characteristics of the metal foil side (first metal foil side) peeled from the carrier foil, and Figures 3 (b) and 4 (b) show the charging characteristics. 7 shows the charging characteristics of the (second metal foil side). Further, the diameters and the densities of the fine holes of the first metal foils manufactured in Examples 1 and 2 and Comparative Example 1 were measured by the following methods. Further, the tensile strength was measured. The results are shown in Table 1 below. [Method of Evaluating Charging Characteristics]

Metal lithium was used as a counter electrode, the electrodes obtained in Examples and Comparative Examples were used as working electrodes, and both electrodes were opposed to each other with a separator interposed therebetween. LiPF as non-aqueous electrolyte

6 A non-aqueous electrolyte secondary battery was fabricated by a conventional method using a mixed solution of Z-ethylene carbonate and getyl carbonate (1: 1 volume ratio). Using this battery, evaluation was performed under charging conditions of 0.2 mA and a voltage range of 0 to 2.8 V.

[Method of Measuring Diameter and Existence Density of Micropores]

Light was transmitted from the back side of the metal foil in the dark room, and a picture of the metal foil was taken under that condition

. The photograph was subjected to image analysis to determine the diameter and density of the micropores.

[Table 1]

As is clear from the results shown in FIGS. 3 (a) and 3 (b) and FIGS. 4 (a) and 4 (b), the negative electrode of Example 1 had a sufficient capacity on both the carrier foil peeling side and the coated side. It can be seen that is obtained. This means that in the negative electrode of Example 1, the electrolyte was sufficiently supplied to the active material layer through the first and second metal foils. On the other hand, in the negative electrode of Comparative Example 1, it was found that sufficient capacity was obtained on both the carrier foil peeling side and the coating-coated side, and it was not found. This means that in the negative electrode of Comparative Example 1, the electrolyte was sufficiently supplied to the active material layer through the first and second metal foils.

As is clear from the results shown in Table 1, the first metal foil (metal foil manufactured according to the manufacturing method of the present invention) obtained in Example 1 has fine pores. It can be seen that it has the same tensile strength as the first metal foil obtained in Comparative Example 1 having no micropores of the same thickness. High tensile strength is also obtained for the first metal foil obtained in Example 2. FIG. 5 shows a scanning electron micrograph of the surface state of the first metal foil in the negative electrode obtained in Example 2. As is clear from this photographic power, it can be seen that many fine holes are formed in the first metal foil.

Industrial applicability

[0058] As described in detail above, according to the present invention, the metal foil is thin and has low stiffness and is not easy to handle. Since the metal foil is attached to the carrier foil, the handleability of the metal foil is good. become. In particular, since the metal foil is porous, it has low strength and is easily broken, but according to the present invention, such inconvenience is unlikely to occur. In addition, the porous metal foil from which the carrier foil has also been peeled has high strength and high flexibility since the conductive polymer is attached to one surface thereof. Further, according to the method for producing a porous metal foil with a carrier foil of the present invention, the diameter of the micropores formed in the metal foil divided by the existing density can be freely controlled. Further, in the negative electrode manufactured by the manufacturing method of the present invention, since the flow path of the electrolyte is sufficiently ensured, the capacity of the nonaqueous electrolyte secondary battery is increased, and the active material absorbs and desorbs lithium. The loss of electrode force due to storage is effectively prevented, and the cycle characteristics are improved.

Claims

The scope of the claims

[I] A porous metal foil layer formed by electroplating on a conductive carrier foil, and a bonding interface layer formed using a conductive polymer between the two. A porous metal foil with a carrier foil.

[2] The porous metal foil with a carrier foil according to claim 1, wherein the conductive polymer is a lithium ion conductive polymer.

3. The porous metal foil with a carrier foil according to claim 2, wherein the conductive polymer is a fluorine-containing conductive polymer.

4. The porous metal foil with a carrier foil according to claim 3, wherein the conductive polymer is polyvinylidene fluoride.

5. The carrier foil according to claim 1, wherein the carrier foil is an electrolytic foil, and a surface of the carrier foil that contacts the bonding interface layer is a deposition surface when the electrolytic foil is manufactured. Porous metal foil with carrier foil.

6. The porous metal foil with a carrier foil according to claim 5, wherein a surface roughness Ra of a surface of the carrier foil that contacts the bonding interface layer is 0.05 to 5 IX m.

[7] The metal foil is at least one of Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag and Au.

2. The porous metal foil with a carrier foil according to claim 1, comprising one kind of metal.

[8] The method according to claim 8, wherein the carrier foil is configured to include at least one metal selected from the group consisting of Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, Au, Al and Ti. The porous metal foil with the carrier foil according to item 1.

[9] The porous polymer foil obtained by peeling the porous metal foil layer from the porous metal foil with a carrier foil according to claim 1, wherein the conductive polymer adheres to one surface of the porous metal foil layer. And a porous metal foil.

[10] A non-aqueous electrolyte comprising a porous metal foil obtained by peeling the porous metal foil layer from the porous metal foil with a carrier foil according to claim 1. Negative electrode for secondary batteries.

[II] A negative electrode for a non-aqueous electrolyte secondary battery according to claim 10 is provided. Non-aqueous electrolyte secondary battery.

[12] The method for producing a porous metal foil with a carrier foil according to claim 1, wherein a coating liquid containing the conductive polymer is applied to one surface of the carrier foil, and an electrolytic solution is applied thereon. A method for producing a porous metal foil with a carrier foil, wherein the metal foil layer is formed by plating.

[13] Prior to applying the coating liquid, the coating surface of the carrier foil to which the coating liquid is applied is subjected to a release treatment with a release agent, or the application surface of the coating liquid after applying the coating liquid. 13. The production method according to claim 12, wherein said is subjected to a release treatment with a release agent.

14. The production method according to claim 13, wherein the release agent has a nitrogen-containing compound or a sulfur-containing compound.

15. The manufacturing method according to claim 12, wherein the carrier foil has a rough surface on one side and an electrolytic metal foil having a smooth surface on the other side, and the coating liquid is applied on the rough surface. .

16. The production method according to claim 15, wherein the surface roughness Ra of the rough surface is 0.05 to 5 μm.

17. The method according to claim 12, wherein the metal foil includes at least one metal selected from the group consisting of Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, and Au. Production method.

[18] The method according to claim 18, wherein the carrier foil comprises at least one metal selected from the group consisting of Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, Au, Al and Ti. The production method described in paragraph 12.

[19] A non-aqueous electrolytic solution comprising a pair of current collecting surface layers whose surfaces are in contact with the electrolytic solution, and an active material layer containing active material particles having a high ability to form a lithium compound interposed between the surface layers. A method for producing a negative electrode for a secondary battery, comprising:

A coating solution containing a conductive polymer is applied to one surface of the carrier foil, and a metal material having a low ability to form a lithium compound is electroplated thereon to form one current-collecting surface layer. A conductive slurry containing particles of an active material is applied on the surface layer for power application to form an active material layer, and a metal material having a low ability to form a lithium compound is electrolytically deposited on the active material layer to form an active material layer. Forming a current collecting surface layer, and then separating and separating the carrier foil from the one current collecting surface layer.