JP4298578B2 - Porous metal foil with carrier foil and method for producing the same - Google Patents

Description

  The present invention relates to a porous metal foil with a carrier foil and a method for producing the same. Moreover, this invention relates to the manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries.

  Porous metal foils are widely used as, for example, battery current collectors and catalyst carriers. In this type of porous metal foil manufacturing method, for example, (a) an insulating film having a desired shape is formed on the electrode surface, and electrolytic plating is performed on the insulating film, whereby electrodeposition is performed on a portion corresponding to the film. (B) A method for producing a porous metal foil by sintering a fibrous or granular metal to form a porous sintered body, (c) A method for producing a metal foil by rolling or electrolytic plating. Then, there is a method of punching this to make a hole.

  Among these various methods, as a method for producing a porous metal foil by electrolytic plating, for example, a metal electrodeposited substrate is roughened by sandblasting, chemical etching, electrolytic etching, machining, etc. Insulating paint is roughly sprayed on the surface, or an insulating coating or oxide film is provided on the entire surface, followed by partial and incomplete removal of coatings such as wire brushes and puffs, and then electrolytic plating is applied to the metal. A method for producing a foil is known (see Patent Document 1). A porous body can be obtained by peeling the obtained metal foil from the substrate.

  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 with ethylene fluoride, and electrolytic plating is performed thereon. A method for producing a metal foil is known (see Patent Document 2). This method utilizes the fact that hydrogen bubbles generated on the electrode plate surface during electroplating remain on the electrode plate surface, resulting in insufficient contact with the electrolyte solution and no electrodeposition on that portion. ing.

JP 50-141540 A JP-A-5-23760

  However, with any of the above-described techniques, the metal foil obtained thereby is not easy to increase strength because it is porous. Further, since an insulating material is applied to the electrode surface, it is not easy to improve the efficiency of electrodeposition. Furthermore, in the technique described in Patent Document 1, since it is essential to roughen the electrode surface, a roughening treatment of the electrode is required prior to electrolytic plating, which complicates the manufacturing process. In addition, since the metal foil is thin and weak, the handleability is not good for processing and transporting the metal foil alone.

  Accordingly, an object of the present invention is to provide a porous metal foil and a method for producing the same, which can eliminate the various disadvantages of the above-described prior art.

  The present invention has a porous metal foil layer formed by electrolytic plating on a conductive carrier foil, and further has a bonding interface layer formed by using a conductive polymer between them. The object is achieved by providing a porous metal foil with a carrier foil.

Further, the present invention is a method for producing the porous metal foil with a carrier foil,
A method for producing a porous metal foil with a carrier foil, characterized in that a coating liquid containing the conductive polymer is applied to one surface of the carrier foil, and the metal foil is formed thereon by electrolytic plating. It is.

  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. A porous metal foil is provided. A negative electrode for a non-aqueous electrolyte secondary battery comprising the porous metal foil obtained by peeling off the porous metal foil from the porous metal foil with a carrier foil, and the negative electrode A non-aqueous electrolyte secondary battery is provided.

Further, the present invention provides a non-aqueous solution comprising a pair of current collecting surface layers whose surfaces are in contact with an electrolytic solution, and an active material layer containing particles of an active material having a high ability to form a lithium compound interposed between the surface layers. A method for producing a negative electrode for an electrolyte 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, and the current collecting surface A conductive slurry containing active material particles is applied onto the layer to form an active material layer, and a metal material having a low lithium compound forming capacity is electroplated on the active material layer to collect the other material A method for producing a negative electrode for a non-aqueous electrolyte secondary battery is provided, wherein a surface layer is formed and then the carrier foil is peeled and separated from the one current collecting surface layer.

  According to the present invention, since the metal foil that is thin and weak and has poor handleability is attached to the carrier foil, the handleability of the metal foil is improved. In particular, since the metal foil is porous, its strength is low and it is easily broken, but according to the present invention, such inconveniences are unlikely to occur. In addition, the porous metal foil peeled from the carrier foil has high strength and high flexibility because the conductive polymer is attached to one surface thereof. Moreover, according to the manufacturing method of the porous metal foil with a carrier foil of this invention, the hole diameter and presence density of the micropore formed in metal foil can be controlled freely. Furthermore, since the negative electrode manufactured by the manufacturing method of the present invention has a sufficient flow path for the electrolyte solution, the capacity of the nonaqueous electrolyte secondary battery is increased, and the active material absorbs and desorbs lithium. This effectively prevents the electrode from falling off and improves the cycle characteristics.

  Hereinafter, the present invention will be described based on preferred embodiments thereof. 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 this embodiment has a three-layer structure having a porous metal foil layer on the carrier foil and further having a bonding interface layer therebetween. The bonding interface layer is in direct contact with each of the carrier foil and the porous metal foil.

  The metal foil is formed by electrolytic plating. The metal foil is a porous one having many fine holes. The metal foil has both a fine hole penetrating through the metal foil in the thickness direction and a fine hole blocked in the middle. Among these, the micropore referred to in the present invention means a micropore penetrating the metal foil in the thickness direction. However, this does not exclude the metal foil having micropores that are blocked in the middle of the present invention. Nor does it mean that such a metal foil is not preferred.

  There is no restriction | limiting in particular in the thickness of metal foil, Appropriate thickness is selected according to the specific use. For example, when used as an electrode material for a non-aqueous electrolyte secondary battery shown in FIG. 2 to be described later, it is possible to ensure mechanical strength, easily form micropores, improve energy density, From the viewpoint of smooth circulation, the thickness is preferably 1 to 100 μm, more preferably 2 to 20 μm, and still more preferably 3 to 10 μm.

  The metal foil can be composed of various metal materials. For example, a metal foil containing at least one metal selected from Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, and Au can be used. That is, a metal foil can be formed from a simple substance of these metals, two or more alloys of these metals, or a material containing other elements in addition to these. When a metal foil is used as the electrode material of the non-aqueous electrolyte secondary battery shown in FIG. 2, which will be described later, it is composed of Cu, Ni, Co, Fe, Cr, Au and has low reactivity with lithium. It is preferable from the point.

  The carrier foil is used as a support for producing a porous metal foil. Further, the manufactured porous metal foil is supported before use or during processing, and is used for improving the handleability of the metal foil. From these viewpoints, it is preferable that the carrier foil has such strength that no twist or the like is generated in the manufacturing process of the metal foil and the processing / conveying process after the manufacturing. Therefore, the thickness of the carrier foil is preferably about 10 to 50 μm.

  In view of the manufacturing method described later, a carrier foil having conductivity is used. In this case, the carrier foil may not be made of metal as long as it has conductivity. However, the use of a metal carrier foil has the advantage that the carrier foil can be melted and made after the production of the porous metal foil and recycled. When a metal carrier foil is used, the carrier foil includes at least one metal selected from Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, Au, Al, and Ti. It is preferable.

  As the carrier foil, for example, a foil manufactured by various methods such as a rolled foil and an electrolytic foil can be used without particular limitation. Unlike the conventional method for producing a porous metal foil, the present invention does not necessarily require that the surface of the carrier foil is roughened. However, from the viewpoint of controlling the hole diameter and density of the fine holes, it is preferable that the surface of the carrier foil has a certain uneven shape. Each surface of the rolled foil is smooth due to its manufacturing method. On the other hand, one surface of the electrolytic foil is a rough surface, and the other surface is a smooth surface. A rough surface is a precipitation surface at the time of manufacturing electrolytic foil. Thus, if the rough surface of the electrolytic foil is used as the electrodeposition surface, it is convenient because it eliminates the need for a separate roughening treatment on the carrier foil. When such a rough surface is used as an electrodeposited surface, the surface roughness Ra is 0.05 to 5 μm, particularly 0.2 to 0.8 μm, so that micropores having a desired diameter and density can be easily obtained. It is preferable because it can be formed.

  Between the carrier foil and the porous metal foil, a joint interface layer of both foils is interposed. The bonding interface layer is formed by applying and drying a coating liquid containing a conductive polymer. The bonding interface layer is used for the purpose of 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 carrier foil consists of electrolytic foil, it is preferable that the surface which contact | connects a joining interface among the surfaces of this carrier foil becomes a precipitation surface at the time of manufacturing this electrolytic foil.

  There is no restriction | limiting in particular in the kind as a conductive polymer which comprises a joining interface layer, A conventionally well-known thing can be used. Examples thereof include poly (vinylidene fluoride) (PVDf), polyethylene oxide (PEO), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA). In particular, when a porous metal foil is used as a negative electrode material for a non-aqueous electrolyte secondary battery, it is preferable to use a lithium ion conductive polymer as the conductive polymer. Regardless of the specific application of the porous metal foil, the conductive polymer 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, it is particularly preferable to use poly (vinylidene fluoride), which is a fluorine-containing polymer having lithium ion conductivity.

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

  In the porous metal foil with carrier foil of the present embodiment, the metal foil may be peeled off from the carrier foil after predetermined processing is completed on the metal foil. Or what is necessary is just to peel metal foil from carrier foil just before performing a predetermined process with respect to metal foil. As a result, the handleability of the thin metal foil having a thin thickness is remarkably improved.

  In the porous metal foil peeled from the porous metal foil with a carrier foil of this embodiment, a conductive polymer derived from the bonding interface layer is attached to one surface. This adhesion gives the metal foil the desired strength and flexibility. The conductive polymer may continuously cover the entire area of one surface of the porous metal foil, or may be discontinuously coated in an island shape. According to the study by the present inventors, it has been found that the strength and flexibility of the metal foil can be improved even if the conductive polymer merely coats one surface of the porous metal foil discontinuously. Of particular note is that even if the pores of the porous metal foil are closed with a conductive polymer, lithium ion conductivity is exhibited when the metal foil is used as a negative electrode material for a non-aqueous electrolyte secondary battery. It is to be.

  Next, the manufacturing method of metal foil with a carrier foil of this invention is demonstrated, referring FIG. First, a carrier foil 1 is prepared as shown in FIG. When the carrier foil 1 is made of an electrolytic foil, as shown in the figure, one surface of the carrier foil 1 is a rough surface 1a and the other surface is a smooth surface 1b. Of these surfaces, it is preferable to use the rough surface 1a 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 1 a of the carrier foil 1. The stripping agent is used for successfully stripping the metal foil from the carrier foil 1 in the stripping step described later. The peeling process is performed by, for example, a chromium plating process, a nickel plating process, a lead plating process, a chromate process, or the like. Moreover, the peeling process using the peeling agent which consists of organic compounds 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 compounds include benzotriazole (BTA), carboxybenzotriazole (CBTA), tolyltriazole (TTA), N ′, N′-bis (benzotriazolylmethyl) urea (BTD-U), and 3-amino. Triazole compounds such as -1H-1,2,4-triazole (ATA) are preferably used. Examples of the sulfur-containing compound include mercaptobenzothiazole (MBT), thiocyanuric acid (TCA), 2-benzimidazolethiol (BIT), and the like. The peelability can be controlled by the concentration of the release agent and the coating amount. The step of applying the release agent is only performed in order to successfully release the metal foil from the carrier foil 1 in the release step described later. Therefore, even if this process is omitted, a metal foil having fine holes can be formed.

  Next, as shown in FIG.1 (b), after apply | coating a peeling agent (not shown), the coating liquid containing a conductive polymer is apply | coated and dried, and the coating film 2 is formed. Or after apply | coating a coating liquid, you may peel-process the application surface of this coating liquid with a peeling agent. The coating liquid is obtained by dissolving a conductive polymer in a volatile organic solvent. As the organic solvent, for example, when polyvinylidene fluoride is used as the conductive polymer, N-methylpyrrolidinone or the like can be used. As shown in FIG. 1B, since the coating liquid is applied to the rough surface 1a of the carrier foil 1, it tends to accumulate in the recesses on the rough surface 1a. When the solvent volatilizes in this state, the thickness of the coating film 2 becomes non-uniform. 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.

  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 constituting the coating film has electronic conductivity, although not as much as metal. Therefore, the coating film 2 has different electron conductivity depending on its thickness. As a result, when a metal is deposited on the coating film 2 containing a conductive polymer by electrolytic plating, a difference occurs in the electrodeposition rate depending on the electron conductivity, and the difference in the electrodeposition rate causes a fine hole 4 in the metal foil 3. Is formed. That is, the portion where the electrodeposition rate is low, in other words, the portion where the coating film 2 is thick is likely to become the fine holes 4.

  As described above, the hole diameter and density of the fine holes 4 can be controlled by the surface roughness Ra of the rough surface 1a. In addition to this, the fine holes 4 can also be controlled by the concentration of the conductive polymer contained in the coating liquid. It is possible to control the pore size and the density of existence. For example, when the concentration of the conductive polymer is low, the pore diameter tends to be small and the existence density tends to be small. Conversely, when the concentration of the conductive polymer is high, the pore diameter tends to increase.

  The concentration of the conductive polymer in the coating liquid becomes a dominant factor of the strength and flexibility of the obtained metal foil in addition to the dominant factor of the pore size and density of the fine pores. For example, when the concentration of the conductive polymer is increased, the strength and flexibility of the obtained metal foil tend to be improved. From these various viewpoints, the concentration of the conductive polymer in the coating liquid is preferably 0.05 to 5% by weight, particularly 1 to 3% by weight.

In FIG. 1 (c), the fine holes 4 are depicted so as to correspond to the thick part of the coating film 2. However, this is convenient for explaining the mechanism of formation of the micropores 4 in the manufacturing method of the present invention, and the micropores 4 are not necessarily formed corresponding to the thick part of the coating film 2. Absent. The plating bath and 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 made of Ni, 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 A / dm ² .
・ NiSO ₄・ 6H ₂ O 150 ~ 300g / l
・ NiCl ₂ .6H ₂ O 30-60 g / l
・ H ₃ BO ₃ 30-40 g / l

  If the metal foil 3 is manufactured by the above method, it is easy to freely control the hole diameter and density of the fine holes 4. In addition, the strength and flexibility of the metal foil can be easily controlled. Moreover, in the present invention, the metal foil is electrodeposited on a new surface, that is, the surface of the carrier foil that is replaced every time it is manufactured. As a result, the state of the surface can always be kept constant, so that the control of the hole diameter, density, strength and flexibility can be performed precisely. In the conventional electrolytic foil manufacturing method, the surface on which the metal foil is electrodeposited is always the same surface, that is, the peripheral surface of the drum cathode body, so that the state of the surface changes with time.

  The metal foil 3 thus obtained has micropores 4 of preferably 0.01 to 200 [mu] m, more preferably 0.05 to 50 [mu] m, and still more preferably 0.1 to 10 [mu] m, depending on the production conditions. Many are formed. When the metal foil 3 having the fine holes 4 in this range is used as, for example, an electrode material for a non-aqueous electrolyte secondary battery shown in FIG. 2 to be described later, the distribution of the non-aqueous electrolyte is maintained while maintaining the strength of the metal foil 3. Can be secured sufficiently. Further, it is possible to effectively prevent the active material from falling off due to the absorption and desorption of lithium.

For the same reason, the micropores 4 having the above-mentioned diameters are 5 to 10,000, particularly 500 to 8000, particularly 1000 to 6000, within an area of 1 cm ^2, no matter which part of the metal foil 3 is taken. It is preferable that it exists with a density of existence. The measuring method of the hole diameter and the existence density of the fine holes 4 will be described in the examples described later.

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

  In the negative electrode 6 shown in FIG. 2, it is preferable that the materials constituting the metal foils 3 a and 3 b penetrate throughout the thickness direction of the active material layer 5. The active material particles 7 are preferably present in the permeated material. Thereby, the adhesiveness 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 electronic conductivity is ensured between the metal foils 3a and 3b and the active material through the material that has penetrated into the active material layer 5, it is possible to generate an electrically isolated active material, in particular, the active material layer 5 The generation of an electrically isolated active material in the deep part of the substrate is effectively prevented, and the current collecting function is maintained. As a result, functional degradation as a negative electrode is suppressed. In addition, the life of the negative electrode can be extended. This is particularly advantageous when a material that is a semiconductor and has poor electronic conductivity, such as a silicon-based material, is used as the active material.

  The material constituting the metal foils 3a and 3b present in the active material layer 5 preferably penetrates the active material layer 5 in the thickness direction. Thereby, the metal foils 3a and 3b are electrically connected through the material, and the electronic conductivity of the negative electrode 6 as a whole 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 thickness direction of the active material layer 5 and the metal foils are connected to each other can be obtained by electron microscope mapping using the material as a measurement object. . Further, when the material constituting the metal foils 3a and 3b enters a part of the fine holes in at least one of the metal foils 3a and 3b (the metal foil 3a in FIG. 2), an active material is obtained by an 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 has entered the fine holes so as not to completely fill the fine holes from the viewpoint of ensuring the circulation of the electrolytic solution. A preferred method for infiltrating the material constituting the metal foils 3a and 3b into the active material layer will be described later.

  In the negative electrode 6 shown in FIG. 2, since the active material layer 5 is sandwiched between the pair of metal foils 3a and 3b, the particles of the active material repeatedly expand and contract due to the absorption and desorption of lithium. Also, it is difficult for the negative electrode 2 to fall off. Further, the anchor effect described above improves the adhesion between the active material layer 5 and the metal foils 3a and 3b. As a result, cycle characteristics are improved. Moreover, since the metal foils 3a and 3b are thin, 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 D50 of the active material particles is 0.1 to 30 [mu] m, preferably 0.5 to _{5 [} mu] m. 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 in this way, a battery can be increased in capacity and energy density.

  The negative electrode 6 shown in FIG. 2 can be manufactured using the manufacturing method of the porous metal foil with a carrier foil described above. For example, first, a porous metal foil with a carrier foil is produced according to the method shown in FIGS. This is used as one metal foil 3a. Next, the active material layer 5 is formed on the metal foil 3a without peeling the metal foil 3a from the carrier foil. The active material layer 5 is formed, for example, by applying a paste containing active material particles or conductive material particles.

On the active material layer 5, a coating liquid containing a carbonaceous material (for example, acetylene black) having an average particle diameter D _{50 of 2} to 200 nm is applied in a thickness of 0.001 to 1 μm. 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 electrolytic plating 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, and electrolytic plating is performed in this state. As a result, (b) the inside of the active material layer 5, (b) the outer surface side of the active material layer 5 (that is, the surface side in contact with the plating solution), and (c) the inner surface side of the active material layer 5 (that is, the metal foil 3a). The metal material is deposited on the surface facing the surface. As a result, the metal foil 3b is formed, and the material constituting the metal foil 3b penetrates over the entire thickness direction of the active material layer 5 and reaches the metal foil 3a. A part thereof enters a part of the fine hole of the metal foil 3a. Finally, the metal foil 3a produced first is peeled from 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, the metal foils 3a and 3b have substantially the same size of micropores and the existence density thereof.

In the negative electrode 6 thus obtained, the conductive polymer is attached to the outer surface of the metal foil 3a. The negative electrode 6 is used together with a known positive electrode, separator, and nonaqueous electrolyte solution to form a nonaqueous 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 it to a current collector, drying it, then rolling and pressing, and further cutting. It is obtained by punching. As the positive electrode active material, conventionally known positive electrode active materials such as lithium nickel composite oxide, lithium manganese composite oxide, and lithium cobalt composite oxide are used. As the separator, a synthetic resin nonwoven fabric, polyethylene, polypropylene porous film, or the like is preferably used. In the case of a lithium secondary battery, the nonaqueous electrolytic solution is a solution in which a lithium salt that is a supporting electrolyte is dissolved in an organic solvent. The lithium salt, for _{example, LiC1O 4, LiA1Cl 4, LiPF} 6, LiAsF 6, LiSbF 6, LiSCN, LiC1, LiBr, LiI, etc. _{LiCF 3 SO 3, LiC 4 F} 9 SO 3 are exemplified.

  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 such examples.

[Example 1]
A copper carrier foil (thickness 35 μm) obtained by electrolysis was acid-washed at room temperature for 30 seconds. Subsequently, it was washed with pure water at room temperature for 30 seconds. Subsequently, the carrier foil was immersed in a 3.5 g / l CBTA solution maintained at 40 ° C. for 30 seconds. In this way, peeling treatment was performed. After the peeling treatment, the substrate was pulled up from the solution and washed with pure water for 15 seconds.

A coating solution having a concentration of 2.5% by weight in which polyvinylidene fluoride was dissolved in N-methylpyrrolidinone was applied to the rough surface of the carrier foil (surface roughness Ra = 0.5 μm). After the solvent was volatilized and a coating film was formed, electrolytic plating was performed by immersing the carrier foil in a watt bath having the following bath composition. Thus, a first metal foil made of nickel was formed on the coating film. The current density was 5 A / dm ² , the bath temperature was 50 ° C., and the pH was 5. A nickel electrode was used as the anode. A DC power source was used as the power source. The metal foil was formed to a thickness of 5 μm. After lifting from the plating bath, it was washed with pure water for 30 seconds and dried in the air. In this way, a porous metal foil with a carrier foil was obtained.
・ NiSO ₄・ 6H ₂ O 250g / l
・ NiCl ₂・ 6H ₂ O 45g / l
・ H ₃ BO ₃ 30g / l

Next, a slurry containing negative electrode active material particles was applied to a thickness of 15 μm on the metal foil to form an active material layer. The active material particles were an alloy having a composition of Si 80 wt% -Ni 20 wt%, and the average particle diameter was D ₅₀ = 1.5 μm. The composition of the slurry was active material: Ni powder: acetylene black: polyvinylidene fluoride = 60: 34: 1: 5.

On the active material layer, a paste containing a carbonaceous material (acetylene black) having an average particle diameter D ₅₀ of 40 nm was applied so as to have a film thickness of 0.5 μm. Subsequently, electrolytic plating was performed on the coating film under the same conditions as described above to form a second metal foil made of nickel. The metal foil was formed to a thickness of 3 μm.

  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 this negative electrode had polyvinylidene fluoride attached to the outer surface of the first metal foil.

[Example 2]
Instead of the watt bath used in Example 1, H ₂ SO ₄ / CuSO ₄ series plating baths were used to form first and second metal foils made of copper. The composition of the plating bath was 250 g / l for CuSO _{4 and} 70 g / l for H ₂ SO ₄ . The current density was 5 A / dm ² . Except this, it carried out similarly to Example 1, and obtained the negative electrode for nonaqueous electrolyte secondary batteries.

[Comparative Example 1]
A copper carrier foil (thickness 35 μm) obtained by electrolysis was acid-washed at room temperature for 30 seconds. Subsequently, it was washed with pure water at room temperature for 30 seconds. Next, the carrier foil was peeled off 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 and electrolytic plating was performed to form a first metal foil made of nickel. The electrolysis conditions were the same as in Example 1. An active material layer was formed by applying a slurry containing negative electrode active material particles on the first metal foil to a thickness of 15 μm. The same active material and slurry as those in Example 1 were used. On the active material layer, electrolytic plating was performed under the same conditions as in Example 1 to form a second metal foil made of nickel. The metal foil was formed to a thickness of 3 μm. 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 method. The results are shown in FIGS. 3 and 4, (a) shows the charging characteristics on the metal foil side (first metal foil side) peeled from the carrier foil, and (b) shows the charging on the coating plating side (second metal foil side). Show properties. Further, the diameter and density of the fine holes of the first metal foils produced in Examples 1 and 2 and Comparative Example 1 were measured by the following method. Furthermore, the tensile strength was measured. The results are shown in Table 1 below.

[Charging characteristics evaluation method]
Metal lithium was used as the counter electrode, and the electrodes obtained in the examples and comparative examples were used as the working electrode, and both electrodes were opposed to each other via a separator. Using a mixed solution (1: 1 volume ratio) of LiPF ₆ / ethylene carbonate and diethyl carbonate as the non-aqueous electrolyte, a non-aqueous electrolyte secondary battery was produced by a normal method. Using this battery, the evaluation was performed under charging conditions of 0.2 mA / cm ² and a voltage range of 0 to 2.8 V.

[Method for measuring diameter and density of micropores]
Light was transmitted from the back side of the metal foil in a dark room, and a photograph of the metal foil was taken under this condition. The photograph was subjected to image analysis to determine the diameter and density of the micropores.

  As is apparent from the results shown in FIGS. 3 and 4, it can be seen that the negative electrode of Example 1 has a sufficient capacity on both the carrier foil peeling side and the coating plating side. This means that in the negative electrode of Example 1, the electrolyte is sufficiently supplied to the active material layer through the first and second metal foils. On the other hand, in the negative electrode of the comparative example 1, it turns out that sufficient capacity | capacitance is not obtained on the carrier foil peeling side and the coating plating side. This means that in the negative electrode of Comparative Example 1, the electrolytic solution is not sufficiently supplied to the active material layer through the first and second metal foils.

  Further, as is clear from the results shown in Table 1, the first metal foil obtained in Example 1 (metal foil produced according to the production method of the present invention) has the same thickness despite having fine holes. It can be seen that it has a tensile strength comparable to that of the first metal foil obtained in Comparative Example 1 having no fine holes. 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 apparent from this photograph, it can be seen that a large number of fine holes are formed in the first metal foil.

It is process drawing which shows the manufacturing method of the porous metal foil of this invention. It is a schematic diagram which shows the structure of the negative electrode for nonaqueous electrolyte secondary batteries provided with the metal foil of this invention. It is a figure which shows the charge characteristic of the negative electrode obtained in Example 1. FIG. It is a figure which shows the charge characteristic of the negative electrode obtained by the comparative example 1. 4 is a scanning electron micrograph of the surface state of the first metal foil in the negative electrode obtained in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carrier foil 2 Coating film 3 Metal foil 4 Micropore 5 Active material layer 6 Negative electrode 7 Active material

Claims (19)

  It has a porous metal foil layer formed by electrolytic plating on a conductive carrier foil, and further has a bonding interface layer formed using a conductive polymer between them. Porous metal foil with carrier foil.   The porous metal foil with a carrier foil according to claim 1, wherein the conductive polymer is a lithium ion conductive polymer.   The porous metal foil with a carrier foil according to claim 1 or 2, wherein the conductive polymer is a fluorine-containing conductive polymer.   The porous metal foil with a carrier foil according to any one of claims 1 to 3, wherein the conductive polymer is polyvinylidene fluoride.   The carrier foil according to any one of claims 1 to 4, wherein the carrier foil is an electrolytic foil, and a surface of the surface of the carrier foil that is in contact with the bonding interface layer is a precipitation surface when the electrolytic foil is produced. With porous metal foil.   6. The porous metal foil with a carrier foil according to claim 1, wherein the surface roughness Ra of the surface of the carrier foil in contact with the bonding interface layer is 0.05 to 5 μm.   7. The metal foil according to claim 1, wherein the metal foil includes at least one metal selected from Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, and Au. Porous metal foil with carrier foil.   8. The carrier foil according to claim 1, wherein the carrier foil includes at least one metal selected from the group consisting of Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, Au, Al, and Ti. A porous metal foil with a carrier foil according to claim 1.   It is obtained by peeling off the porous metal foil from the porous metal foil with a carrier foil according to claim 1, and the conductive polymer is adhered to one surface of the porous metal foil layer. Porous metal foil.   A negative electrode for a nonaqueous electrolyte secondary battery, comprising a porous metal foil obtained by peeling the porous metal foil from the porous metal foil with a carrier foil according to claim 1.   A nonaqueous electrolyte secondary battery comprising the negative electrode for a nonaqueous electrolyte secondary battery according to claim 10. A method for producing a porous metal foil with a carrier foil according to claim 1,
A method for producing a porous metal foil with a carrier foil, wherein a coating liquid containing the conductive polymer is applied to one surface of the carrier foil, and the metal foil is formed thereon by electrolytic plating.   Prior to application of the coating liquid, the coating surface of the coating liquid on the carrier foil is stripped with a release agent, or the coating surface of the coating liquid is applied after the coating liquid is applied. The production method according to claim 12, wherein a peeling treatment is performed by the step.   The method according to claim 13, wherein the release agent comprises a nitrogen-containing compound or a sulfur-containing compound.   The manufacturing method according to any one of claims 12 to 14, wherein the carrier foil is made of an electrolytic metal foil whose one surface is a rough surface and the other surface is a smooth surface, and the coating liquid is applied onto the rough surface. .   The manufacturing method according to claim 15, wherein the rough surface has a surface roughness Ra of 0.05 to 5 μm.   17. The metal foil according to any one of claims 12 to 16, wherein the metal foil includes at least one kind of metal selected from Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, and Au. Production method.   18. The carrier foil according to claim 12, wherein the carrier foil includes at least one metal selected from Cu, Ni, Co, Fe, Cr, Sn, Zn, In, Ag, Au, Al, and Ti. The manufacturing method of crab. A non-aqueous electrolyte secondary battery comprising a pair of current collecting surface layers whose surfaces are in contact with an electrolytic solution, and an active material layer including active material particles having a high ability to form a lithium compound interposed between the surface layers A negative electrode manufacturing method for
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, and the current collecting surface A conductive slurry containing active material particles is applied onto the layer to form an active material layer, and a metal material having a low lithium compound forming capacity is electroplated on the active material layer to collect the other material A method for producing a negative electrode for a non-aqueous electrolyte secondary battery, wherein a surface layer is formed, and then the carrier foil is peeled and separated from the one current collecting surface layer.