JP5407550B2 - Current collector for positive electrode of nonaqueous electrolyte secondary battery, electrode using the same, and production method thereof - Google Patents

Description

  In particular, the present invention provides a positive electrode current collector for a non-aqueous electrolyte secondary battery using an aluminum porous sintered body suitable for a lithium ion secondary battery or a lithium ion polymer secondary battery, and an electrode using the same, and The present invention relates to a manufacturing method thereof.

  In recent years, non-aqueous electrolyte secondary batteries, particularly lithium ion batteries and lithium ion polymer batteries, have come to be used in electric vehicles, hybrid vehicles, and the like. In addition, it is required to cope with high reliability, high output, and high energy density. Currently, aluminum foil is generally used as the positive electrode current collector of these batteries, but an aluminum porous body having open pores of a three-dimensional network structure is becoming known as an electrode current collector ( Patent Documents 1 and 2).

  As a method for producing such an aluminum porous body, for example, after thickening molten aluminum with a thickener, titanium hydride is added as a foaming agent, and hydrogen gas generated by a thermal decomposition reaction of titanium hydride is used. There is known a foam melting method in which molten aluminum is solidified while being foamed (Patent Document 3). However, the foamed aluminum obtained by this method had large closed pores of several mm.

  In addition, as a second method, there is a method of obtaining foamed aluminum having a sponge skeleton by press-fitting aluminum into a mold having sponge urethane as a core and filling aluminum into a cavity formed by burning out urethane. According to this method, a foamed aluminum having a pore diameter of 40 PPI or less, that is, a pore diameter of 40 cells or less per inch (pore diameter: about 600 μm or more) is obtained.

Further, as a third method, there is a method in which aluminum is foamed by decomposition of TiH ₂ powder by heating and rolling a mixed powder of AlSi alloy powder and TiH ₂ powder between aluminum plate materials. The foamed aluminum to be obtained has a large pore diameter of several mm (Patent Document 4).

  Furthermore, as a fourth method, there is a method in which a metal having a eutectic temperature with aluminum lower than the melting point of aluminum is mixed with aluminum and heated and fired at a temperature higher than the eutectic temperature and lower than the melting point of aluminum. (Patent Document 5) The foamed aluminum obtained by the same method has a porosity as small as about 40% even if the pore diameter can be reduced. For this reason, the amount of the positive electrode active material and the negative electrode active material penetrating into the pores of the foamed aluminum as the current collector is small, and the desired high output and high energy density cannot be achieved.

  Therefore, among the above-described methods, the second method can be adopted as a method for producing foamed aluminum having minute open pores that can achieve the objectives of high reliability, high output, and high energy density. .

  However, even in this second method, in order to further reduce the pore diameter of the open pores, it is necessary to use fine sponge urethane, and the flow of aluminum becomes worse, making it impossible to press-fit or casting. Since the pressure becomes too high, it is difficult to produce foamed aluminum having a pore diameter smaller than 40 PPI.

  On the other hand, a foaming slurry containing metal powder and a foaming agent is used as a method for producing a high-porosity foam metal having small pore sizes and sized open pores in which a large number of minute open pores are evenly arranged. There is a slurry foaming method in which the material is foamed, dried and then sintered (Patent Document 6). According to this method, if a raw material powder that can be sintered is available, it is a high-porosity foam metal having dimensionally open pores having an arbitrary pore size ranging from about 10 PPI to about 500 PPI, that is, a pore size ranging from 2.5 mm to 50 μm. Can be easily manufactured. The slurry foaming method means a method in which a foamed metal is obtained by foaming by adding a foaming agent to a slurry containing metal powder, or by foaming by gas injection or stirring, drying, and sintering. .

  However, conventionally, in the slurry foaming method, it was difficult to produce foamed aluminum because non-pressure sintering of aluminum could not be performed due to the presence of an oxide film on the surface of the aluminum powder. Even if aluminum foam can be produced, pure aluminum is soft, so when filling the pores with the active material and rolling to increase the energy density, the aluminum foam breaks. There is a concern that

Japanese Patent No. 3591055 JP 2009-43536 A Japanese Patent Application Laid-Open No. 08-209265 Special table 2003-520292 gazette Japanese Examined Patent Publication No. 61-48566 Japanese Patent No. 3535282

  The present inventors have found that by using a sintering aid containing titanium, a high-strength aluminum porous sintered body can be produced by non-pressure sintering. In the present invention, this aluminum porous sintered body is applied to a current collector of an electrode for a non-aqueous electrolyte secondary battery, and fine carbon fibers (particularly, carbon nanofibers) are placed in the pores of the aluminum porous sintered body. A collector for a positive electrode of a non-aqueous electrolyte secondary battery that enables higher output, higher reliability, and higher energy density of the non-aqueous electrolyte secondary battery, and an electrode using the same The issue is to provide.

The present invention relates to a current collector for a positive electrode of a non-aqueous electrolyte secondary battery that solves the above-described problems with the following configuration, a non-aqueous electrolyte secondary battery electrode using the same, and a method for producing the same.
(1) A porous aluminum sintered body and a positive electrode current collector for a non-aqueous electrolyte secondary battery including fine carbon fibers in the pores of the aluminum porous sintered body, the aluminum porous sintered body A non-aqueous electrolyte secondary characterized in that the body has a metal skeleton of a three-dimensional network structure, has pores between the metal skeletons, and an Al-Ti compound is dispersed in the metal skeleton. A current collector for a positive electrode of a battery.
(2) The positive electrode current collector of the nonaqueous electrolyte secondary battery according to (1), wherein the aluminum porous body contains 0.1 to 20 parts by mass of titanium with respect to 100 parts by mass of aluminum and titanium in total. .
(3) The positive electrode current collector of the nonaqueous electrolyte secondary battery according to (1) or (2) above, wherein the average crystal grain size of the aluminum porous sintered body is 10 to 100 μm.
(4) Current collector for positive electrode of nonaqueous electrolyte secondary battery according to any one of (1) to (3) above, wherein the fine carbon fibers are carbon nanofibers having an average fiber diameter of 1 nm to 1 μm and an aspect ratio of 5 or more. body.
(5) The active material and a binder are further included in the pores of the aluminum porous sintered body of the positive electrode current collector of the nonaqueous electrolyte secondary battery according to any one of (1) to (4) above. Non-aqueous electrolyte secondary battery electrode.
(6) having a metal skeleton of a three-dimensional network structure, having pores between the metal skeletons, and pores of the aluminum porous sintered body in which an Al-Ti compound is dispersed in the metal skeleton, A method for producing a current collector for a positive electrode of a non-aqueous electrolyte secondary battery, wherein the fine carbon fiber dispersion is filled and dried.
(7) The positive electrode current collector of the nonaqueous electrolyte secondary battery according to (6), wherein the aluminum porous body contains 0.1 to 20 parts by mass of titanium with respect to 100 parts by mass of aluminum and titanium in total. Manufacturing method.
(8) The non-hole according to the above (6) or (7), wherein the total porosity of the aluminum porous sintered body is 70 to 99% by forming 20 or more holes per 1 cm of linear length A method for producing a current collector for a positive electrode of a water electrolyte secondary battery.
(9) Filling the pores of the aluminum porous sintered body of the positive electrode current collector of the nonaqueous electrolyte secondary battery according to any one of (1) to (4) above with a slurry containing an active material and a binder And then, after drying, rolling, a method for producing an electrode for a non-aqueous electrolyte secondary battery.
(10) A nonaqueous electrolyte secondary battery including the electrode for a nonaqueous electrolyte secondary battery according to (5) above.

  According to the present invention (1), the active material can be satisfactorily held in the pores of the aluminum porous sintered body, and the current collector and the active material can be obtained by the fine carbon fibers in the pores of the aluminum porous sintered body. It is possible to provide a current collector for a positive electrode of a nonaqueous electrolyte secondary battery that can easily produce a positive electrode of a nonaqueous electrolyte secondary battery excellent in conductivity between substances. Furthermore, since the aluminum porous sintered body by dispersion of the Al—Ti compound has high strength, the active material is further contained in the pores of the aluminum porous sintered body, and then rolling is performed. It is possible to provide a current collector that can easily produce a positive electrode of a non-aqueous electrolyte secondary battery having high output density, high reliability, and high energy density.

  According to the present invention (5), the active material is satisfactorily held in the pores of the aluminum porous sintered body, and the current collector and the active material are formed by the fine carbon fibers in the pores of the aluminum porous sintered body. A positive electrode of a nonaqueous electrolyte secondary battery having excellent conductivity between substances can be provided. Furthermore, since the aluminum porous sintered body by dispersion of the Al—Ti compound has high strength, the active material is further contained in the pores of the aluminum porous sintered body, and then rolling is performed. A positive electrode of a non-aqueous electrolyte secondary battery having high output density, high reliability, and high energy density can be provided.

  According to the present invention (6), it is possible to easily produce a positive electrode of a non-aqueous electrolyte secondary battery having a high output density, a high reliability, and a high energy density. Electricity can be obtained.

  According to the present invention (9), a highly reliable electrode for a non-aqueous electrolyte secondary battery can be easily obtained, and an aluminum porous sintered body in which a high-strength Al—Ti compound is dispersed is used. Thus, rolling becomes possible, and it becomes possible to easily produce a high-power density and high-energy density non-aqueous electrolyte secondary battery electrode.

It is a scanning electron micrograph of the aluminum porous sintered compact of an Example. 2 is a partially enlarged scanning electron micrograph of FIG. 3 is a partially enlarged scanning electron micrograph of FIG. It is an example of the secondary electron image of an aluminum porous sintered compact. It is an example of Ti mapping of EPMA of an aluminum porous sintered body. It is sectional drawing of the coin cell produced by the Example and the comparative example.

  Hereinafter, the present invention will be specifically described based on embodiments. Unless otherwise indicated,% is based on mass unless otherwise specified.

[Current collector for positive electrode of non-aqueous electrolyte secondary battery]
The positive electrode current collector of the non-aqueous electrolyte secondary battery of the present invention includes an aluminum porous sintered body and a positive electrode of a non-aqueous electrolyte secondary battery containing fine carbon fibers in the pores of the aluminum porous sintered body. The aluminum porous sintered body has a three-dimensional network structure composed of a sintered metal skeleton (hereinafter referred to as a metal skeleton), and has pores between the metal skeletons. In addition, an Al—Ti compound is dispersed in the metal skeleton.

  FIG. 1 is a scanning electron micrograph of the porous aluminum sintered body before rolling produced in the example, FIG. 2 is a partially enlarged scanning electron micrograph of FIG. 1, FIG. A partially enlarged scanning electron micrograph is shown. As apparent from FIGS. 1, 2, and 3, the porous aluminum sintered body forms pores by a metal skeleton having a three-dimensional network structure. In addition, the metal skeleton itself has a feature of high porosity.

  In order to obtain the desired aluminum porous sintered body strength, pore diameter, and porosity, the metal skeleton of the aluminum porous sintered body has a metal skeleton diameter (the thickness of the thinnest part of each metal bone forming the metal skeleton). Is preferably 5 to 100 μm. The metal skeleton preferably has skeleton vacancies having a pore diameter of 0.1 to 3 μm. Here, the metal skeleton diameter and the pore diameter of the skeleton vacancies are measured by scanning electron micrographs of the skeleton surface and the skeleton cross section.

  The interstitial vacancies are preferably communicated from the viewpoint of easily including an active material, a binder, and the like, and ensuring good conductivity with the electrolyte.

  From the viewpoint of filling a desired amount of active material, the pore diameter of the inter-framework holes is preferably 20 to 500 μm. After rolling, the pore diameter of the interstitial pores becomes an elliptical shape having a long longitudinal direction of the aluminum porous sintered body. The pore diameter in the longitudinal direction is preferably 30 to 600 μm, and the voids in the thickness direction are preferred. The pore diameter is preferably 10 to 200 μm. Here, the pore diameter is measured by scanning electron micrographs of the surface and cross section of the sample.

  The total porosity of the aluminum porous sintered body is preferably 70 to 99%, more preferably 80 to 97%, from the viewpoint of filling a desired amount of active material. In addition, the porosity after rolling is preferably 10 to 60%, and more preferably 15 to 40%. Here, the porosity is calculated from the dimensions, mass, and density of the porous aluminum sintered body.

  The metal skeleton is preferably formed of aluminum crystal grains having an average crystal grain size of 10 to 100 μm, and more preferably 15 to 60 μm. Due to the presence of irregularities formed by the grain boundary steps caused by the crystal grains, the anchor effect works and has excellent adhesion to fine carbon fibers, active materials, conductive assistants, and binders. A highly reliable electrode for a non-aqueous electrolyte secondary battery with excellent material retention can be obtained, but the number and size of the irregularities are affected by the aluminum crystal grain size. The dimension becomes small and a sufficient anchor effect is not exhibited. On the other hand, when the crystal grain size of the aluminum crystal grains of the metal skeleton is larger than 100 μm, the retention of the active material is lowered and the strength of the aluminum porous sintered body is lowered. Here, the crystal grain size is measured by a line intercept method from an optical micrograph or a scanning electron micrograph. The aluminum crystal grains more preferably have a crystal grain size of 70% or more in the range of 15 to 60 μm.

  The Al—Ti compound having a metal skeleton is derived from titanium contained in a sintering aid used when producing an aluminum porous sintered body. Titanium not only makes it possible to produce an aluminum porous sintered body by pressureless sintering, but also makes the aluminum porous sintered body high strength, especially high tensile, by forming an Al-Ti compound. Make it strong.

  It is preferable that an aluminum porous body contains 0.1-20 mass parts of titanium with respect to a total of 100 mass parts of aluminum and titanium. If titanium is less than 0.1 part by mass, a good aluminum porous sintered body cannot be obtained. If it exceeds 20 parts by mass, sintering aid powder containing titanium in the aluminum mixed raw material powder at the time of sintering. They come to have contacts, making it impossible to control the reaction heat between aluminum and titanium, and making it impossible to obtain a desired porous sintered body. Here, the quantitative analysis of aluminum and titanium is performed by the ICP method.

  From the viewpoint of improving the energy density of the nonaqueous electrolyte secondary battery, the thickness of the aluminum porous sintered body is preferably 0.05 to 5 mm before rolling, and more preferably 0.1 to 3 mm. The thickness of the aluminum porous sintered body is preferably 0.03 to 3 mm after rolling, and more preferably 0.8 to 2.5 mm.

  The width of the aluminum porous sintered body is generally determined from the shape of the non-aqueous electrolyte secondary battery, but after producing the aluminum porous sintered body with a width corresponding to a plurality of widths, an active material is contained. And after rolling, it can also be made into the width | variety for one piece with a slit etc.

  Since the aluminum porous sintered body is usually produced in a roll shape, the length of the aluminum porous sintered body is usually produced by a length corresponding to many pieces, contains an active material, and is rolled. The length is one by cutting.

  Examples of the fine carbon fibers contained in the pores of the aluminum porous sintered body include carbon nanofibers, carbon black, acetylene black, ketjen black, and the like, with an average fiber diameter of 1 nm to 1 μm and an aspect ratio of 5 The above carbon nanofiber is preferable. This fine carbon fiber enters not only interstitial vacancies but also intra-skeletal vacancies, and can form a good conductive path between the aluminum porous sintered body and the active material after filling with the active material. Carbon nanofibers can also form a network-like conductive film on the surface of the metal skeleton.

The carbon nanofiber has a volume resistance value of 1.0 Ω · cm or less of the compacted carbon fiber so that good conductivity is obtained, and the stacking interval of the [002] plane of the graphite layer is 0 by X-ray diffraction measurement. What is .35 nm or less is preferable. Here, the volume resistance value is obtained by putting the sample powder in a cylindrical donut-shaped PP insulating jig, pressurizing both ends of the opening with a cylindrical brass electrode at 100 kgf / cm ² , and measuring the resistance value between the brass electrodes with a digital multimeter. And is calculated from this measured value.

  When the fine carbon fiber contained in the pores of the aluminum porous sintered body is 0.3 to 10 parts by mass with respect to 100 parts by mass of the aluminum porous sintered body, It is preferable from the viewpoint of improving the conductivity between the active materials.

[Electrode for non-aqueous electrolyte secondary battery]
Examples of the active material contained in the pores of the porous aluminum sintered body include those used as a positive electrode active material for non-aqueous electrolyte secondary batteries, which can occlude and release lithium ions. If there is, it will not be specifically limited. Conventionally, any material may be used as long as it is generally used. Specifically, it is composed of a composite oxide or salt containing at least one of cobalt, nickel, manganese, titanium, vanadium and iron and lithium. Is preferred. Thereby, a positive electrode active material does not melt | dissolve in electrolyte, but it can be set as a high capacity | capacitance battery.

It said as a positive electrode active material, more specifically, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, Li · Mn-based composite oxide such as spinel LiMn ₂ O ₄ And Li · Fe-based composite oxides such as LiFeO ₂ and transition metal and lithium phosphate compounds such as LiFePO ₄ and sulfuric acid compounds. In addition, transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ ; PbO ₂ , AgO, NiOOH, and the like can also be used. This active material is preferably a powder having an average particle diameter of 2 to 20 μm from the viewpoint of increasing the output of the nonaqueous electrolyte secondary battery. Here, the average particle diameter is measured by a laser diffraction method.

  Examples of the binder contained in the pores of the porous aluminum sintered body together with the active material and the conductive auxiliary agent include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), SBR, and polyimide. It is not limited to these.

  When 100 to 800 parts by mass of the active material is included with respect to 100 parts by mass of the aluminum porous sintered body, it is preferable from the viewpoint of improving the energy density of the nonaqueous electrolyte secondary battery, and more preferably 250 to 750 parts by mass. Here, the quantitative analysis of the active material is performed by the ICP method.

  When the binder is included in an amount of 2 to 80 parts by mass with respect to 100 parts by mass of the aluminum porous sintered body, the active material is appropriately retained in the pores of the aluminum porous sintered body and the loss of the active material is prevented. From the viewpoint, it is more preferable to include 6 to 60 parts by mass.

  Moreover, it is preferable from the viewpoint of high output that a conductive additive is further contained in the pores of the aluminum porous sintered body. Examples of the conductive assistant include, but are not limited to, natural graphite and artificial graphite in addition to the carbon nanofiber, carbon black, acetylene black, and ketjen black.

  When 1 to 100 parts by mass of a conductive auxiliary agent is contained with respect to 100 parts by mass of the aluminum porous sintered body, it is preferable from the viewpoint of increasing the output of the nonaqueous electrolyte secondary battery and preventing loss of the active material. More preferably, 70 parts by mass is included.

  In the present invention, the pores of the aluminum porous sintered body contain an active material and a binder, and in some cases, a conductive additive, but the aluminum porous sintered body as a current collector and An active material and a binder, and optionally a conductive auxiliary agent may also be included between the separators. In the present invention, the active material contained in the pores of the aluminum porous sintered body, the binder, and the active material, the binder and the conductive additive in the nonaqueous electrolyte secondary battery in a total of 100 parts by mass. It is preferable from a viewpoint of the improvement of the high energy density of a nonaqueous electrolyte secondary battery and high output that a conductive support agent is 60-95 mass parts.

  The nonaqueous electrolyte when using the electrode for a nonaqueous electrolyte secondary battery of the present invention may be any of a liquid electrolyte (electrolyte), a solid electrolyte, and a polymer gel electrolyte. The nonaqueous electrolyte is not particularly limited as long as it is used in a normal secondary battery, although a preferred example is shown below.

As an electrolytic solution, LiBOB (lithium bis oxide _{borate), LiPF 6, LiBF 4,} LiClO 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 inorganic acid anion salts ₁₀ such as _Cl, LiCF 3 _{SO 3,} It contains at least one electrolyte salt selected from organic acid anion salts such as Li (CF ₃ SO ₂ ) ₂ N and Li (C ₂ F ₅ SO ₂ ) ₂ N, and includes propylene carbonate (PC), ethylene Cyclic carbonates such as carbonate (EC);
Chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate; ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane; γ- Lactones such as butyrolactone; Nitriles such as acetonitrile; Esters such as methyl propionate; Amides such as dimethylformamide; Aprotic mixed with at least one selected from methyl acetate and methyl formate The thing using organic solvents (plasticizer), such as a solvent, can be used.

The solid electrolyte is not particularly limited as long as it is composed of a polymer having ion conductivity. For example, in the case of an inorganic solid electrolyte, thiolithicone, Li ₄ SiO ₄ —Li ₃ BO ₃ , LiX—Li ₂ O—MmOn (X = I, Br, Cl; M = B, Si, P, etc., m, (wherein n is a number from 1 to 5), and the like. Examples of the polymer solid electrolyte include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. Is mentioned. A polyalkylene oxide polymer exhibits excellent mechanical strength by dissolving the above-described electrolyte salt well and forming a crosslinked structure.

  The polymer gel electrolyte is not particularly limited, but the same electrolyte solution is held in the skeleton of the electrolyte polymer having an ionic conductivity or the electrolyte polymer having no ionic conductivity. And the like.

  The electrolyte solution contained in the polymer gel electrolyte is the same as described above. Further, as the electrolyte polymer having ion conductivity, the above-described solid electrolyte or the like is used.

  Examples of the electrolyte polymer having no ionic conductivity include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) copolymer, polyvinyl chloride (PVC), polyacrylonitrile (PAN), Monomers that form gelling polymers such as polymethyl methacrylate (PMMA) can be used. However, it is not necessarily limited to these. Note that PAN, PMMA, etc. are in a class that has almost no ionic conductivity, and therefore can be used as an electrolyte polymer having the above ionic conductivity. It was exemplified as a polymer for electrolyte that does not have ionic conductivity.

  The ratio (mass ratio) between the electrolyte polymer (host polymer) and the electrolyte solution in the polymer gel electrolyte may be determined according to the purpose of use, but is in the range of 2:98 to 90:10. Thereby, it can seal effectively also about the oozing-out of the electrolyte from the outer peripheral part of an electrode active material layer by providing an insulating layer and an insulation process part.

  The positive electrode current collector of the nonaqueous electrolyte secondary battery of the present invention is very effectively used as a highly reliable, high energy density, high output nonaqueous electrolyte secondary battery electrode.

[Method for producing current collector for positive electrode of non-aqueous electrolyte secondary battery]
The method for producing a current collector for a positive electrode of a non-aqueous electrolyte secondary battery according to the present invention includes a metal skeleton having a three-dimensional network structure, pores between the metal skeletons, and Al—Ti in the metal skeleton. The porous carbon sintered body in which the compound is dispersed is filled with a fine carbon fiber dispersion and dried.

  The aluminum porous sintered body can be manufactured as follows.

  First, aluminum mixed raw material powder is prepared by mixing titanium powder and / or titanium hydride with aluminum powder to obtain an aluminum mixed raw material powder (aluminum mixed raw material powder preparation step). The aluminum mixed raw material powder is mixed with a water-soluble resin binder, water, and a plasticizer to prepare a viscous composition (viscous composition preparation step). This viscous composition is dried in a state where air bubbles are mixed to form a pre-sintered molded body (pre-sintering process), and the pre-sintered molded body is Tm-10 (° C.) ≦ heat-fired in a non-oxidizing atmosphere. It is heated and fired at a temperature (T) ≦ 685 (° C.) (sintering step). Here, Tm (° C.) is a temperature at which the aluminum mixed raw material powder starts to melt.

  In this aluminum mixed raw material powder preparation step, aluminum powder having an average particle size of 2 to 200 μm is used. Here, when the average particle size is reduced, the aluminum powder is used in order that the viscous composition is so viscous that it can be formed into a desired shape, and that the pre-sintered compact has handling strength. A large amount of water-soluble resin binder must be added. However, if a large amount of the water-soluble resin binder is added, the amount of carbon remaining in the aluminum increases when the pre-sintered molded body is heated and fired, and the sintering reaction is hindered. On the other hand, when the particle diameter of the aluminum powder is too large, the strength of the aluminum porous sintered body is lowered. Therefore, as the aluminum powder, those having an average particle diameter in the range of 2 to 200 μm, preferably 4 to 100 μm, more preferably 4 to 60 μm, and further preferably 7 to 40 μm are used as described above. Here, the average particle diameter is measured by a laser diffraction method.

This aluminum powder is mixed with a sintering aid containing titanium, specifically, titanium and / or titanium hydride. Thereby, titanium is mixed with aluminum powder, and when the pre-sintered compact is heated and fired at Tm-10 (° C.) ≦ heating and firing temperature T ≦ 685 (° C.), a lump of droplets is generated. No pressureless sintering of aluminum is possible. Further, titanium hydride (TiH ₂ ) has a titanium content of 47.88 (molecular weight of titanium) / (47.88 + 1 (molecular weight of hydrogen) × 2) and is 95% by mass or more, and is 470 to 530 ° C. In order to dehydrogenate, it is thermally decomposed into titanium during the above-mentioned heating and firing. Therefore, even when titanium hydride is mixed, non-pressure-sintering of aluminum can be performed without generating droplet lumps. As the sintering aid, a sintering aid powder other than titanium or titanium hydride may be used, or a sintering aid powder containing titanium may be used.

  The sintering aid containing titanium preferably contains 0.1 to 20 parts by mass of titanium with respect to a total of 100 parts by mass of aluminum and titanium.

  Here, when the average particle diameter of titanium and / or titanium hydride is r (μm) and the blending ratio of titanium and / or titanium hydride is W (mass%), 1 (μm) ≦ r ≦ 30 ( μm), 0.1 (mass%) ≦ W ≦ 20 (mass%), and preferably 0.1 ≦ W / r ≦ 2. That is, in the case of titanium hydride powder having an average particle size of 4 μm, since 0.1 ≦ W / 4 ≦ 2, the compounding ratio W is preferably 0.4 to 8% by mass. In the case of titanium powder having an average particle diameter of 20 μm, the blending ratio: W is 2 to 40% by mass from the condition of 0.1 ≦ W / 20 ≦ 2, but the blending ratio: W is 0. .1 (mass%) ≦ W ≦ 20 (mass%) is added, and 2 to 20 mass% is preferable.

  The average particle size of titanium hydride is preferably 0.1 (μm) ≦ r ≦ 30 (μm), more preferably 4 (μm) ≦ r ≦ 20 (μm). If the average particle size of titanium hydride is smaller than 0.1 μm, there is a risk of spontaneous ignition, and if it exceeds 30 μm, the Al—Ti compound is formed from the titanium particles coated with the Al—Ti compound produced by sintering. This is because the phases are easily separated and desired strength cannot be obtained in the sintered body.

  Further, 0.1 (mass%) ≦ W ≦ 20 (mass%) is preferable because when the mixing ratio W of the sintering aid powder exceeds 20 mass%, the sintering aid powder in the aluminum mixed raw material powder. This is because they have contact points, making it impossible to control the reaction heat between aluminum and titanium, and making it impossible to obtain a desired porous sintered body.

  However, when tested under various conditions, the reaction heat between aluminum and titanium is large depending on the particle size of the sintering aid powder even within the range of 0.1 (mass%) ≦ W ≦ 20 (mass%). In some cases, the temperature of the aluminum melted by the reaction heat rises further, the viscosity decreases, and droplets may be generated.

  Therefore, from the results of observing specimens prepared under various conditions with an electron microscope, within a range in which the calorific value can be controlled by the blending amount of titanium and the particle diameter, the thickness of the titanium particles is almost constant from the exposed surface side. Only the surface layer was found to react with aluminum. Thus, it was experimentally found that it is desirable that 1 (μm) ≦ r ≦ 30 (μm) and 0.1 ≦ W / r ≦ 2 in order to prevent the generation of droplets.

  Next, in the viscous composition preparation step, at least one selected from the group consisting of polyvinyl alcohol, methylcellulose and ethylcellulose as a water-soluble resin binder is added to the aluminum mixed raw material powder as a plasticizer, and polyethylene glycol, glycerin and phthalate as plasticizers. At least one selected from the group consisting of di-n-butyl acid is added, and distilled water and alkylbetaine as a surfactant are added.

  Thus, when polyvinyl alcohol, methylcellulose, or ethylcellulose is used as the water-soluble binder, the amount added is relatively small. Therefore, the addition amount of the water-soluble resin binder is 0.5 to 7 parts by mass with respect to 100 parts by mass of the aluminum mixed raw material powder. When the amount is more than 7 parts by mass with respect to 100 parts by mass of the aluminum mixed raw material powder, the sintering reaction is hindered by an increase in the amount of carbon remaining in the pre-sintered molded body before heating and firing, and 0.5 parts by mass It is because the handling intensity | strength of the molded object before sintering is not ensured that it is less than.

  Moreover, 0.02-3 mass parts of alkylbetaines are added with respect to 100 mass parts of mass of aluminum mixed raw material powder. When the amount is 0.02 parts by mass or more with respect to 100 parts by mass of the aluminum mixed raw material powder, bubbles are effectively generated when the water-insoluble hydrocarbon organic solvent described later is mixed, and 3 parts by mass or less. In this case, inhibition of the sintering reaction due to an increase in the amount of carbon remaining in the green body before sintering is prevented.

  And after kneading | mixing these, it is made to foam by mixing a C5-C8 water-insoluble hydrocarbon-type organic solvent, and the viscous composition with which the bubble was mixed is adjusted. As the water-insoluble hydrocarbon organic solvent having 5 to 8 carbon atoms, at least one selected from the group consisting of pentane, hexane, heptane and octane can be used.

  In the next pre-sintering step, doctor blade method, slurry extrusion method, screen printing method, etc., so that the viscosity composition has a thickness of 0.05 mm to 5 mm on the stripping surface of the strip-shaped polyethylene sheet After the coating, the ambient temperature and humidity are controlled for a certain period of time, the air bubbles are sized, and then dried at a temperature of 70 ° C. with an air dryer.

  And the viscous composition after drying is peeled off from a polyethylene sheet, it cuts out in a desired shape, and the molded object before sintering is obtained.

  In the next sintering step, the above-mentioned pre-sintered compact is placed on an alumina setter coated with a powder such as zirconia and heated at 520 ° C. for 1 hour in an argon atmosphere with a dew point of −20 ° C. or lower. Pre-baking is performed. This removes the binder that volatilizes and / or decomposes the binder solution of the water-soluble resin binder component, plasticizer component, distilled water and alkylbetaine of the green body before sintering, and also hydrogenates as a sintering aid powder. When titanium is used, dehydrogenation is performed.

  Thereafter, the pre-sintered compact after preliminary firing is fired at Tm-10 (° C.) ≦ heat firing temperature (T) ≦ 685 (° C.) to obtain an aluminum porous sintered body.

  Here, the pre-sintered compact is considered to start the reaction between aluminum and titanium when heated to Tm (° C.): 660 ° C., which is the melting temperature of aluminum. The melting point is lowered by the eutectic alloy elements such as Fe and Si contained, and in fact, the reaction between aluminum and titanium is started by heating at Tm-10 (° C.), and an aluminum porous sintered body is formed. Is done. Specifically, while the melting point of aluminum is 660 ° C., the melting start temperature is around 650 ° C. for atomized powder having a purity of about 98% to 99.7% distributed as pure aluminum powder. On the other hand, if the heating and firing temperature is maintained at a temperature higher than 685 ° C., aluminum droplet-like lumps are generated in the sintered body.

  In addition, in order to suppress the growth of the oxide film of the aluminum particle surface and the titanium particle surface, it is necessary to perform the heat baking in the sintering process in a non-oxidizing atmosphere. However, if the heating temperature is 400 ° C. or less and maintained for about 30 minutes, the oxide film on the aluminum particle surface and the titanium particle surface does not grow so much even when heated in air. After debinding by heating and holding at 300 ° C. to 400 ° C. for about 10 minutes in air, it may be fired at a predetermined temperature in an argon atmosphere.

  Here, the non-oxidizing atmosphere means an atmosphere that includes an inert atmosphere or a reducing atmosphere and does not oxidize the aluminum mixed raw material powder. In addition, the above-described heating and firing temperature is not the temperature of the aluminum mixed raw material powder, that is, the reaction temperature of the aluminum mixed raw material powder or the like, but means the holding temperature around the aluminum mixed raw material powder. .

  The aluminum porous sintered body thus obtained has a metal skeleton with a three-dimensional network structure, has pores between the metal skeletons, and the Al-Ti compound is almost uniformly formed on the metal sintered body. Are dispersed. FIG. 4 shows an example of a secondary electron image of an aluminum porous sintered body and Ti mapping of EPMA. As is apparent from FIG. 4, Al—Ti compounds are dispersed almost uniformly (5 to 100 in the range of 200 μm square).

  The aluminum porous sintered body has a non-aqueous electrolyte in which the total porosity of the aluminum porous sintered body is 70 to 90% by forming 20 or more pores per 1 cm of linear length. From the viewpoint of improving the energy density of the secondary battery electrode or increasing the output, it is preferable as a current collector for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery or a lithium ion polymer battery, particularly as a current collector for a positive electrode. Preferably used.

  In addition, the aluminum porous sintered body is composed of 2 pores derived from bubbles at the time of slurry foaming in the above viscous composition preparation step and pores formed in the metal skeleton itself derived from being a sintered body. Has different types of holes. Here, the realization of high reliability by holding the active material, which is a remarkable effect of the present invention, is that the vacancies between the skeletons of the aluminum porous sintered body and the vacancies in the skeleton formed in the metal skeleton itself are This is probably due to a synergistic effect.

  The fine carbon fibers contained in the pores of the porous aluminum sintered body should be made hydrophilic by oxidizing the surface in order to obtain a good dispersion state without using a dispersant in the liquid. Is preferred. In addition, by the hydrophilization treatment, the fine carbon fibers are well dispersed in the aqueous solution and no dispersant is required, so that no gas is generated due to decomposition of the dispersant, and a positive electrode having excellent output characteristics can be formed. .

  Generally, carbon materials have hydrophobicity and are difficult to disperse in an aqueous solution. Therefore, conventionally, a carbon-based conductive material is dispersed using a dispersant. For this reason, when forming the positive electrode, the dispersant is inevitably taken into the positive electrode structure, which decomposes and causes gas generation. On the other hand, fine carbon fibers whose surfaces have been hydrophilized by oxidation treatment can maintain a good dispersion state in an aqueous solution without the need for a dispersant.

  For the oxidation treatment of fine carbon fibers, for example, a sulfur-containing strong acid such as sulfuric acid is added to fine carbon fibers, an oxidizing agent such as nitric acid is added, the slurry is stirred under heating, and then filtered to wash away residual acid. And then remove it. This oxidation treatment forms a polar functional group such as a carbonyl group, a carboxyl group, or a nitro group, and is considered to be hydrophilic. Moreover, this process can also reduce a catalyst, when a catalyst, such as a fiber metal, is used for manufacture of a fine carbon fiber.

  The solvent for the fine carbon fiber dispersion is preferably a polar solvent, and for example, N-methylpyrrolidone, dimethylacetamide, dimethylformamide, water and the like can be used.

  The fine carbon fiber dispersion is recovered by filtering and separating the fine carbon fibers after adding an oxidizing agent to the acidic suspension of the fine carbon fibers and oxidizing it to make the surface of the fine carbon fibers hydrophilic. The fine carbon fiber can be mixed with one or more solvents selected from a solvent and water.

  Next, the fine carbon fiber dispersion is filled in the pores of the aluminum porous sintered body and dried. Examples of the filling method include a method of dipping an aluminum porous sintered body into a fine carbon fiber dispersion, a method of pouring a fine carbon fiber dispersion from the upper part of the aluminum porous sintered body, and the like. The fine carbon fiber is more effectively put into the pores of the aluminum porous sintered body by pushing the dispersion of excess fine carbon fiber adhering to the surface by passing between the rolls of the metal or by rubbing with a spatula. Can be filled. Drying may be left in the air, or a dryer or the like may be used. After drying, the mass ratio between the porous aluminum sintered body and the fine carbon fibers is measured. When the mass ratio of the fine carbon fibers is low, the immersion and drying can be repeated to obtain a desired amount. On the other hand, when the mass ratio of the fine carbon fibers is high, the viscosity of the dispersion can be lowered, and dipping and drying can be performed again to obtain a desired amount.

[Method for producing electrode for nonaqueous electrolyte secondary battery]
The slurry containing the active material and the binder can be obtained, for example, as follows. First, the binder is dissolved or uniformly dispersed in an organic solvent. This mixed solution and the active material powder are mixed to form a slurry. Or after mixing an active material and a binder uniformly, an organic solvent is added and it is set as a slurry. At this time, the apparatus to be used may be those normally used by those skilled in the art, such as a planetary mixer, a ball mill, and a Henschel mixer. Here, the organic solvent has a viscosity that allows the slurry to be easily immersed in the aluminum porous sintered body in the step of immersing the next aluminum porous sintered body in the slurry, for example, 10 to 60 Pa · s. It is preferable to add.

  In addition, when adding a conductive support agent to a slurry, the order in which the conductive support agent is added to the mixed solution may be either before or after the active material powder is added to the mixed solution and simultaneously with the addition of the active material powder.

  Examples of the organic solvent for dissolving or dispersing the binder include tetrahydrofuran (hereinafter referred to as THF), methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, N-methylpyrrolidone, acetone, acetonitrile, dimethyl carbonate, ethyl acetate, butyl acetate, and the like. Although it can be used, in order to selectively remove this organic solvent by drying, a volatile organic solvent having a boiling point of 100 ° C. or lower such as THF or acetone, or N-methylpyrrolidone having a high ability to dissolve a binder is preferable.

  Next, the pores of the aluminum porous sintered body are filled with the slurry of the active material and dried. Examples of the filling method include a method of dipping the aluminum porous sintered body into the slurry of the active material, a method of pouring the slurry from the upper part of the aluminum porous sintered body, and further, passing between two rolls, The active material can be more effectively filled into the pores of the aluminum porous sintered body by pushing the surplus active material slurry adhering to the surface with a spatula into the inside. Drying may be left in the air, or a dryer or the like may be used. After drying, the mass ratio of the aluminum porous sintered body to the active material, the conductive additive and the binder is measured. Drying can be repeated to achieve the desired amount. On the other hand, when the mass ratio of the active material, the conductive additive and the binder is high, the viscosity of the slurry can be lowered, and dipping and drying can be performed again to obtain a desired amount.

  Next, the aluminum porous sintered body containing an active material, a binder, and optionally a conductive additive is rolled to obtain an electrode for a non-aqueous electrolyte secondary battery. Since the aluminum porous sintered body of the present invention has an Al-Ti compound dispersed in a metal skeleton and has high strength, particularly tensile strength, the aluminum porous sintered body can be rolled to a desired thickness. It is possible to decrease the porosity of the electrode body and increase the electrode density. Here, the electrode thickness is preferably 0.03 to 3 mm. Here, the density of the aluminum porous sintered body can be increased by pressing or the like, but rolling is preferable from the viewpoint of productivity.

  The electrode for a nonaqueous electrolyte secondary battery of the present invention is very effectively used for a highly reliable, high energy density, high output nonaqueous electrolyte secondary battery.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

[Production of porous aluminum sintered body]
According to the above-described embodiment, an aluminum porous sintered body was manufactured. First, an aluminum powder having an average particle diameter of 24 μm (containing impurities: Fe: 0.15 mass%, Si: 0.05 mass% and Ni: 0.01 mass%), and hydrogen having an average particle diameter of 9.1 μm The titanium halide powder was mixed at a total of 500 g so that the mass ratio of the aluminum powder and the titanium hydride powder was 99: 1 to prepare an aluminum mixed raw material powder.

  Binder solution: 100 parts by mass of binder solution: 0.1 parts by mass of methyl cellulose, 2.9 parts by mass of ethyl cellulose, 3 parts by mass of glycerin, 3 parts by mass of polyethylene glycol, 0.5 parts by mass of alkyl betaine It was prepared in a total of 500 g at a ratio of part and remaining water.

  Aluminum mixed raw material powder: 50 parts by mass, binder solution: 49 parts by mass, and hexane: 1 part by mass were mixed in a total of 500 g to prepare a viscous composition.

  Next, this viscous composition is stretched and applied onto a polyethylene sheet coated with a release agent by the doctor blade method, and the temperature and humidity are controlled to be maintained for a certain period of time. It dried at the temperature of 70 degreeC with the air dryer. The coating thickness of the viscous composition at this time was 0.35 mm, the temperature was 35 ° C., the humidity was 90 minutes, and the holding time was 20 minutes. Subsequent drying was performed at 70 ° C. for 50 minutes. And the viscous composition after drying was peeled off from the polyethylene sheet, and it cut out to the circular shape of diameter 100mm, and obtained the molded object before sintering.

  This pre-sintered compact was placed on an alumina setter with zirconia powder spread, pre-fired (debindered) in an argon stream, then heat-fired, and aluminum porous sintered Body 1 was obtained. Debinding was performed at 520 ° C. for 30 minutes. Heating and baking were performed at 663 ° C. for 30 minutes in an argon atmosphere to obtain an aluminum porous sintered body 1. The thickness of the obtained aluminum porous sintered body 1 was 1.2 mm.

The shrinkage rate and porosity of the obtained aluminum porous sintered body 1 were calculated. The shrinkage rate was calculated from the change in thickness of the aluminum porous sintered body 1 before and after heating and firing, and the porosity was calculated from the dimensions, mass and density. In addition, the number of three-dimensional vacancies was measured from the stereomicrograph, and the number of vacancies in the skeleton per 100 μm length of the metal skeleton was measured from the scanning electron microscope (SEM) photograph. The presence or absence of solidification was confirmed, and further, the presence or absence of an Al—Ti compound was confirmed on the skeleton surface of the aluminum porous sintered body 1 by surface analysis using an electron beam microanalyzer (EPMA). Here, the number of vacancies in the skeleton per 100 μm length of the metal skeleton was prepared with five scanning electron micrographs of 300 times magnification, each of which was taken from different fields so that the metal skeleton was shown in the center of the photograph. Draw a diagonal line, draw a line segment equivalent to 100 μm in length on the metal skeleton part on the diagonal line from the intersection to the four corners, count the number of vacancies in the skeleton in the metal skeleton of the line segment, and calculate by averaging For the number of interstitial pores, prepare 5 stereomicrographs with a magnification of 10 times for each different field of view, and draw a diagonal line in the same way to create a line segment corresponding to a length of 5 mm on the diagonal line from the intersection to the four corners. It was calculated by drawing four on each photograph, counting the number of metal skeletons crossed by the line segment, and multiplying by 25.4 / 5 on average. These results are shown in Table 1 (here, the unit of the number of inter-frame holes: “PPI” is the number of holes per inch (25.4 mm)). Moreover, the SEM photograph of the obtained aluminum porous sintered compact 1 is shown in FIG. 1, and the one part enlarged photograph is shown in FIG. 2 and FIG. 3, respectively. As is apparent from FIGS. 1 to 3, the surface of the metal skeleton of the aluminum porous sintered body 1 has irregularities formed by grain boundary steps of the aluminum porous sintered body. The average crystal grain size of the body crystal grains was 39 μm. Here, the average crystal grain size of the porous sintered aluminum crystal grains, a measurement sample was filled resin, polished to a mirror surface, Keller reagent (48% hydrofluoric acid: 0.5 cm ^3, concentrated hydrochloric acid: 1. 5 cm ³ , concentrated nitric acid; 2.5 cm ³ , distilled water; 95 cm ³ ) etched by immersion for 30 seconds, photographed with an optical microscope at a magnification of 100 times, line intercept method (ASTM, E-112, Linear Intercept) (Procedure).

Next, the aluminum porous sintered body 1 was roll-rolled at a reduction ratio of 20% and visually checked for the presence of cracks (20% reduction test), and then cut into a 20 mm × 50 mm rectangular shape. The electrical resistivity between the opposite corners was measured. Subsequently, this rectangular aluminum porous sintered body 1 was wound around the outer periphery of a cylindrical body having a diameter of 5 mm, and the presence or absence of cracks was visually confirmed. Table 1 shows these results.

  The aluminum porous sintered body 1 was used except that a titanium hydride powder having an average particle size of 21 μm was used and the mass ratio of the aluminum powder to the titanium hydride powder was 85:15. A sintered material 2 was prepared and subjected to each test. Table 1 shows these results. In addition, the thickness of the obtained aluminum porous sintered body 2 was 1.3 mm.

  As can be seen from Table 1, the obtained aluminum porous sintered bodies 1 and 2 have 3 to 4 pores per 100 μm of the skeleton length of the porous metal sintered body and between the metal skeletons. 52 holes per inch, that is, 20 or more holes per cm. And the droplet-shaped lump did not arise in an aluminum porous sintered compact, the electrical resistivity was low, and there was no crack by a winding test.

  Next, carbon nanofibers (CNF: average fiber diameter 20 nm, aspect ratio: 80) are mixed into a mixed solution of nitric acid (concentration 60%) and sulfuric acid (concentration 95% or more), CNF: nitric acid: sulfuric acid = 1 part by weight: 5 parts by weight: 15 parts by weight was mixed and heated at 120 ° C. for 20 minutes for surface oxidation treatment. The resulting solution was filtered and washed several times with water to wash away the remaining acid. Then, it filtered and the water-containing carbon nanofiber slurry collect | recovered was put into methanol, and it stirred for 15 minutes at 500 rpm, and obtained the CNF dispersion liquid.

Example 1
The produced aluminum porous sintered body 1 was immersed in the CNF dispersion for 10 minutes, taken out and dried to produce a positive electrode current collector.

  From the mass change of the aluminum porous sintered body 1 at this time, the CNF content (parts by mass) relative to 100 parts by mass of the aluminum porous sintered body was calculated. Table 2 shows the results.

(Conventional example 1)
As the foamed aluminum of Conventional Example 1, 30 PPI foamed aluminum produced by press-fitting aluminum into a mold having sponge urethane as a core, which is the second method of the prior art, was used.

  The foamed aluminum of Conventional Example 1 was immersed in the CNF dispersion prepared in Example 1 for 10 minutes, taken out and dried to prepare a current collector for positive electrode of Conventional Example 1 having a thickness of 0.5 mm.

  From the mass change of the foamed aluminum at this time, the CNF content (parts by mass) relative to 100 parts by mass of the foamed aluminum was calculated. Table 2 shows the results. In addition, in Table 2, it described in the column of "Content of CNF (mass part) with respect to 100 mass parts of porous aluminum sintered bodies".

(Examples 2 to 4)
Except for the combinations shown in Table 2, the positive electrodes of the lithium ion batteries of Examples 2 to 4 were produced in the same manner as in Example 1.

  From the mass change of the aluminum porous sintered body at this time, the CNF content (parts by mass) relative to 100 parts by mass of the aluminum porous sintered body was calculated. Table 2 shows these results.

[Manufacture of electrodes for non-aqueous electrolyte secondary batteries]
(Example 5)

A positive electrode agent is prepared by mixing a total of 200 g of lithium cobaltate (LiCoO ₂ ) powder as an active material, CNF as a conductive material, and polyvinylidene fluoride (PVDF) as a binder at a mass ratio of 90: 5: 5. A positive electrode active material slurry was prepared by mixing 176 g of N-methyl-2pyrrolidone as a solvent with this positive electrode agent.

  Next, the positive electrode current collector produced in Example 1 was immersed in this positive electrode active material slurry for 10 minutes, taken out and dried, and then rolled and rolled to a lithium ion battery of Example 5 having a thickness of 0.5 mm. A positive electrode was prepared. Here, the positive electrode current collector is immersed in the positive electrode active material slurry, dried, and then, before rolling, the positive electrode active material slurry adhering to the surface of the positive electrode current collector is wiped off, so that almost the entire amount of the active material and conductivity aid are obtained. The agent and the binder were included in the pores of the positive electrode current collector.

(Examples 6 to 10, Comparative Example 2)
A secondary battery electrode was produced in the same manner as in Example 5 except that the conditions shown in Table 3 were used.

[Performance test of electrode for non-aqueous electrolyte secondary battery]
(Active material packing density)
About the positive electrode of each lithium ion battery of Examples 5 to 10 and Comparative Example 1, from the mass change of the aluminum porous sintered body when producing the positive electrode of the lithium ion battery, the activity with respect to 100 parts by mass of the aluminum porous sintered body The substance content (parts by mass) was calculated. Here, the ratio of the active material, the conductive additive and the binder was calculated on the assumption that the positive electrode active material slurry was still produced. Similarly, the content (parts by mass) of the conductive additive with respect to 100 parts by mass of the aluminum porous sintered body was calculated. Table 4 shows these results.

(Electrode winding test)
Next, cylindrical bodies having diameters of 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, and 5 mm were prepared, and the lithium ion batteries of Examples 1 to 10 and Conventional Example 1 were prepared. Each of the positive electrodes was wound, and whether or not the active material was peeled was visually observed. Table 4 shows the minimum diameter at which no peeling was observed.

(Energy density)
In order to measure the energy density, a coin cell of a non-aqueous electrolyte secondary battery was produced. FIG. 6 shows a cross-sectional view of the used coin cell.

  As the negative electrode 11, a foil-like lithium metal was fitted into a stainless steel battery lid 12 and pressed.

Next, the positive electrode 10 obtained by punching out the positive electrode with a diameter of 15 mmφ was placed in a stainless steel outer can 13, and a polypropylene microporous membrane (thickness: 20 μm) separator 14 was placed thereon. A nonaqueous electrolyte of 1M LiPF ₆ / EC + PC (1: 1 (volume ratio)) was poured into this, and then the battery lid 12 was placed and filled with a sealant 15 made of a mixture of styrene butadiene rubber and pitch without any gaps. This was sealed to prepare a coin cell. The coin cell has a diameter of 20 mm and a height of 3.2 mm.

  The cell was discharged at a discharge rate of 0.2C and a discharge voltage of 4.2 to 2.8V. From the result of the discharge capacity, the energy density of the positive electrode was calculated. Table 5 shows these results. Here, the amount of the positive electrode active material was calculated from the active material packing density and the electrode area, and used for calculation of the energy density.

(Output characteristics)
Using the cell, discharge was performed at a discharge rate of 2C and a discharge voltage of 4.2 to 2.8V. At this time, the voltage drop 0.5 seconds after the start of discharge was measured. Next, (discharge capacity at 0.2 C) / (discharge capacity at 2 C) was calculated, and the output characteristics were evaluated. Table 5 shows these results.

  As can be seen from Table 2, the current collectors of Examples 1 to 4 could contain 0.6 to 1.5 parts by mass of CNF with respect to 100 parts by mass of the aluminum porous sintered body. On the other hand, the conventional foamed aluminum of Comparative Example 1 could contain only 0.2 parts by mass of CNF.

  Moreover, as can be seen from Table 4, in the positive electrodes of Examples 5 to 10, the active material was 290 to 620 parts by mass, and the conductive assistant was 16 to 3 parts by mass with respect to 100 parts by mass of the aluminum porous sintered body. , And could be contained at high density. Moreover, from the result of the electrode winding test, it was also found that the positive electrodes of Examples 5 to 10 are highly reliable because the active material is less likely to fall off. On the other hand, in Comparative Example 2, only 205 parts by mass of the active material can be contained with respect to 100 parts by mass of the foamed aluminum, and the active material was dropped at a diameter smaller than 4 mmφ in the electrode winding test.

Moreover, as can be seen from Table 5, the positive electrodes of Examples 5 to 10 have a high energy density of 778 mWh / cm ³ or more with 0.2 C discharge, and in particular, Example 7 in which the positive electrode slurry was immersed and dried three times. The positive electrode had a high energy density of 905 mWh / cm ³ . In addition, the positive electrodes of Examples 5 to 10 maintain 0.83 or more of the capacity at 0.2C discharge even at 2C discharge, and the voltage drop at 0.2C discharge is as low as 18 to 20 mV, with high output. I found out. Further, when Examples 5, 8 and 9 were compared with Comparative Example 3, it was found that the number of times of immersion and drying in the CNF dispersion was effective even once. On the other hand, Comparative Example 2 using conventional foamed aluminum has a low energy density of 616 Wh / cm ^3, and 2C discharge can only hold a capacity of 0.75 at the time of 0.2C discharge, and output characteristics are also high. It was not good. In Comparative Example 3 not containing CNF, the voltage drop during 2C discharge was 14.9 mV, (discharge capacity at 0.2C) / (discharge capacity at 2C) was 0.80, which was inferior to Examples 5-10. It was a result.

  As described above, a non-aqueous electrolyte secondary battery having high output density, high reliability, and high energy density can be manufactured by using the current collector for a non-aqueous electrolyte secondary battery of the present invention and an electrode using the same. it can.

DESCRIPTION OF SYMBOLS 1 Aluminum porous sintered body 2 Active material, conductive support agent, and binder layer 3 Pore 10 Positive electrode 11 Negative electrode 12 Battery cover 13 Exterior can 14 Separator 15 Sealant

Claims (10)

  An aluminum porous sintered body, and a current collector for a positive electrode of a nonaqueous electrolyte secondary battery containing fine carbon fibers in the pores of the aluminum porous sintered body, wherein the aluminum porous sintered body is: A positive electrode for a non-aqueous electrolyte secondary battery comprising a metal skeleton having a three-dimensional network structure, pores between the metal skeletons, and an Al-Ti compound dispersed in the metal skeleton Current collector.   The current collector for a positive electrode of a nonaqueous electrolyte secondary battery according to claim 1, wherein the aluminum porous body contains 0.1 to 20 parts by mass of titanium with respect to 100 parts by mass of aluminum and titanium in total.   The current collector for a positive electrode of a nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein the average crystal grain size of the aluminum porous sintered body is 10 to 100 µm.   The collector for positive electrodes of the nonaqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the fine carbon fibers are carbon nanofibers having an average fiber diameter of 1 nm to 1 µm and an aspect ratio of 5 or more.   The nonaqueous electrolyte secondary battery further comprising an active material and a binder in the pores of the aluminum porous sintered body of the positive electrode current collector of the nonaqueous electrolyte secondary battery according to any one of claims 1 to 4. Secondary battery electrode.   Fine carbon fiber in the pores of the porous aluminum sintered body having a metal skeleton of a three-dimensional network structure, having pores between the metal skeletons, and having an Al-Ti compound dispersed in the metal skeleton A method for producing a current collector for a positive electrode of a non-aqueous electrolyte secondary battery, wherein the dispersion is filled and dried.   The manufacturing method of the electrical power collector for positive electrodes of the nonaqueous electrolyte secondary battery of Claim 6 with which an aluminum porous body contains 0.1-20 mass parts of titanium with respect to a total of 100 mass parts of aluminum and titanium.   The non-aqueous electrolyte secondary battery according to claim 6 or 7, wherein the total porosity of the aluminum porous sintered body is 70 to 99% by forming 20 or more pores per linear length of 1 cm. A method for producing a current collector for a positive electrode.   The slurry containing the active material and the binder is filled in the pores of the aluminum porous sintered body of the positive electrode current collector of the nonaqueous electrolyte secondary battery according to any one of claims 1 to 4, and dried. A method for producing an electrode for a non-aqueous electrolyte secondary battery, which is then rolled.   A nonaqueous electrolyte secondary battery comprising the electrode for a nonaqueous electrolyte secondary battery according to claim 5.