JP5509786B2 - Positive electrode for non-aqueous electrolyte secondary battery - Google Patents

Description

  The present invention relates to a positive electrode for a non-aqueous electrolyte secondary battery, and more particularly to an electrode using an aluminum porous sintered body suitable for a lithium ion secondary battery or a lithium ion polymer secondary battery.

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, high output and high reliability are required. Therefore, a lithium ion battery in which an inorganic solid electrolyte is dispersed in an electrolytic solution in an electrode is disclosed (Patent Document 1). However, the electric conductivity of the inorganic solid electrolyte is around 10 ⁻³ Ω · cm ⁻¹ (paragraph 0057 of Patent Document 2), and the electrode including the electrolytic solution in which the inorganic solid electrolyte is dispersed has sufficient electric conductivity. Therefore, it cannot be said that it has thermal conductivity, and there is a concern that the temperature inside the electrode, particularly in the center of the electrode, may increase during high power discharge. As a result of intensive studies on improving the electrical conductivity and thermal conductivity of the electrode of the nonaqueous electrolyte secondary battery, particularly the positive electrode, the present inventors have found that the current collector includes an aluminum porous sintered body, and the aluminum porous It is possible to significantly improve the electrical conductivity and thermal conductivity of the positive electrode by realizing an electrode for a secondary battery containing an active material, a conductive additive and a Li ion conductive material in the pores of the sintered body. I found it. Here, at present, aluminum foil is generally used as a positive electrode current collector of these batteries. However, there is a problem in producing an aluminum porous sintered body suitable for a positive electrode for a non-aqueous electrolyte secondary battery.

  As an electrode current collector, an aluminum porous body having open pores with a three-dimensional network structure is becoming known (Patent Documents 3 and 4). As a method for producing such an aluminum porous body, for example, A foaming and melting method is known in which, after thickening molten aluminum with a thickener, titanium hydride is added as a foaming agent, and the molten aluminum is solidified while being foamed by hydrogen gas generated by the thermal decomposition reaction of titanium hydride. (Patent Document 5). 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 produced has a large pore diameter of several mm (Patent Document 6).

  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 7) The foamed aluminum obtained by the same method has a porosity as small as around 40% even though 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-mentioned 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 output, high reliability, 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 a foam is dried and then sintered (Patent Document 8). 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

JP 2008-300193 A JP 2002-109955 A 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 used as a current collector of an electrode for a nonaqueous electrolyte secondary battery, and an active material, a conductive auxiliary agent and Li ion conductivity are provided in the pores of the aluminum porous sintered body. It is an object of the present invention to provide a positive electrode that enables high output and high reliability of a nonaqueous electrolyte secondary battery by containing a substance.

The present invention relates to an electrode for a non-aqueous electrolyte secondary battery that solves the above-described problems with the following configuration and a non-aqueous electrolyte secondary battery using the same.
(1) A current collector comprising an aluminum porous sintered body, and a positive electrode for a secondary battery comprising an active material, a conductive assistant and a Li ion conductive material in the pores of the aluminum porous sintered body. The porous aluminum sintered body has a metal skeleton having a three-dimensional network structure, has pores between the metal skeletons, and an Al ₃ Ti compound is dispersed in the metal skeleton. A positive electrode for a non-aqueous electrolyte secondary battery.
(2) The positive electrode for a nonaqueous electrolyte secondary battery according to (1), wherein the current collector further comprises an aluminum foil or an aluminum plate.
(3) The nonaqueous electrolyte secondary battery according to (1) or (2) above, wherein the aluminum porous sintered body contains 0.1 to 20 parts by mass of titanium with respect to 100 parts by mass of aluminum and titanium in total. Positive electrode.
(4) The positive electrode for a nonaqueous electrolyte secondary battery according to any one of (1) to (3), wherein the Li ion conductive material is a polymer gel electrolyte or a solid electrolyte.
(5) A nonaqueous electrolyte secondary battery including the positive electrode for a nonaqueous electrolyte secondary battery according to any one of (1) to (4) above.

  According to the present invention (1), since the conductive assistant and the Li ion conductive material are present in the pores of the porous aluminum sintered body having the metal skeleton of the three-dimensional network structure, the electric conduction with the active material In addition, a non-aqueous electrolyte secondary battery having a very high heat conductivity and a high output can be obtained. Moreover, since the aluminum porous sintered body by dispersion | distribution of an Al-Ti compound is high intensity | strength, after making an active material contain in the void | hole of an aluminum porous sintered body, it is rolled and a high output density is carried out. In addition, a positive electrode for a non-aqueous electrolyte secondary battery can be provided, and a highly reliable positive electrode for a non-aqueous electrolyte secondary battery having excellent adhesion to an active material conductive additive and a Li ion conductive material can be obtained. It is done.

  According to the present invention (2), it is possible to easily obtain an electrode for a nonaqueous electrolyte secondary battery suitable for higher output.

It is a scanning electron micrograph of the aluminum porous sintered compact of the electrical power collector 1 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 a conceptual diagram of the electrical power collector for positive electrodes provided with the aluminum porous sintered compact and the aluminum plate. It is an image figure of the cross section of the electrode for nonaqueous electrolyte secondary batteries of this invention. It is sectional drawing of the coin cell produced by the Example and the prior art example.

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

[Electrode for non-aqueous electrolyte secondary battery]
A positive electrode for a non-aqueous electrolyte secondary battery according to the present invention includes a current collector provided with an aluminum porous sintered body, and an active material, a conductive auxiliary agent and a Li ion conductive material in the pores of the aluminum porous sintered body. The aluminum porous sintered body has a metal skeleton with a three-dimensional network structure, has pores between the metal skeletons, and the metal skeleton includes Al ₃ Ti. The system compound is dispersed.

The aluminum porous sintered body has a metal skeleton having a three-dimensional network structure, has pores between the metal skeletons, and an Al ₃ Ti compound is dispersed in the metal skeleton.

  FIG. 1 shows a scanning electron micrograph of the porous aluminum sintered body before rolling, which was produced with the current collector 1 of the example, FIG. 2 shows a partially enlarged scanning electron micrograph of FIG. FIG. 2 shows a partially enlarged scanning electron micrograph of FIG. 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.

  In addition, vacancies between metal skeletons (hereinafter referred to as inter-skeleton vacancies) are communicated from the viewpoint of easily including an active material, a Li ion conductive material, and the like, and ensuring good conductivity with an electrolytic solution. It is preferable.

  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 Al ₃ Ti-based 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 atmospheric pressure sintering, but also makes the aluminum porous sintered body high strength, particularly high tensile, by forming an Al ₃ Ti-based compound. Make it strong. Further, it is considered that the Al ₃ Ti-based compound has a low contact resistance and is suitable for higher output due to the presence of the Al ₃ Ti-based compound.

  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.

  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. It is preferable from the viewpoint of the reliability and high output of the secondary battery electrode, and is suitably used as a positive electrode current collector of a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery or a lithium ion polymer battery.

  In addition to the aluminum porous sintered body, the current collector is preferably provided with an aluminum foil or an aluminum plate from the viewpoint of increasing the output. Here, the thickness of the aluminum foil is preferably 10 μm or more and less than 50 μm, and the thickness of the aluminum plate is preferably 50 μm or more and 1 mm or less. In FIG. 4, the conceptual diagram of the electrical power collector for positive electrodes provided with the aluminum porous sintered compact and the aluminum plate is shown. In addition, the aluminum plate can provide the part in which the aluminum porous sintered compact is not formed for tabs like the left part of FIG.

  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 conductive additive contained in the pores of the porous aluminum sintered body include carbon black, acetylene black, ketjen black, natural graphite, and artificial graphite, but are not limited thereto. Not.

  The Li ion conductive material contained in the pores of the aluminum porous sintered body only needs to have Li ion conductivity, and may be either a solid electrolyte or 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.

The solid electrolyte is not particularly limited as long as it is composed of a polymer having ion conductivity. For example, if the solid electrolyte of an inorganic, Chiorishikon and _Li 4 _SiO 4 _{-Li 3} BO 3 or _{LiX-Li 2 O-M m} O n (X = I, Br, Cl; M = B, Si, P , etc. , M and n are numbers from 1 to 5) and the like, and polymer-based solid electrolytes include polyethylene oxide (PEO), polypropylene oxide (PPO), A polymer etc. are mentioned. The polyalkylene oxide polymer exhibits excellent mechanical strength by dissolving the electrolyte salt well and forming a crosslinked structure. Here, as the electrolyte salt, LiBOB (lithium bis oxide _{borate), LiPF 6, LiBF 4,} LiClO 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 Cl 10 inorganic acid anion salts such as, LiCF ₃ Examples thereof include organic acid anion salts such as SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, and the like.

  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. Here, the above-described solid electrolyte or the like is used as the electrolyte polymer having ion conductivity.

  Examples of the electrolyte polymer having no ion conductivity include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) copolymer, polyvinyl chloride (PVC), and 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 electrolytic solution contained in the polymer gel electrolyte includes the above electrolyte salt, cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC); chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate. Ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane; lactones such as γ-butyrolactone; nitriles such as acetonitrile; propionic acid Esters such as methyl; Amides such as dimethylformamide; Those using an organic solvent (plasticizer) such as an aprotic solvent in which at least one selected from methyl acetate and methyl formate is mixed Is mentioned.

  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 pores of the aluminum porous sintered body preferably contain a binder. Examples of the binder include, but are not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), SBR, and polyimide. When a polymer gel electrolyte is used as the Li ion conductive material, the polymer gel electrolyte can also act as a binder.

  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.

  It is preferable to contain 1 to 100 parts by mass of a conductive additive with respect to 100 parts by mass of the aluminum porous sintered body from the viewpoint of increasing the output of the nonaqueous electrolyte secondary battery and preventing loss of the active material.

  From 30 to 400 parts by mass of the Li ion conductive material 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.

  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. It is preferable from the viewpoint.

  In FIG. 5, the image figure of the cross section of the electrode for nonaqueous electrolyte secondary batteries of this invention is shown. It is considered that the active material, the conductive auxiliary agent, the binder, and the Li ion conductive material layer 2 cover the metal skeleton with the pores 3 of the aluminum porous sintered body 1 and reduce the pore volume.

  In the present invention, the pores of the aluminum porous sintered body contain an active material, a conductive additive, and a Li ion conductive material. An active material, a conductive assistant, and a Li ion conductive material may be included between the separators. In the present invention, the active material contained in the pores of the porous aluminum sintered body with respect to a total of 100 parts by mass of the active material in the nonaqueous electrolyte secondary battery, the conductive auxiliary agent and the Li ion conductive material, It is preferable from a viewpoint of the high output of a nonaqueous electrolyte secondary battery that a conductive support agent and Li ion conductive material are 60-95 mass parts.

  Examples of the non-aqueous electrolyte when using the electrode for a non-aqueous electrolyte secondary battery of the present invention include the above-described electrolyte solution, and any non-aqueous electrolyte may be used as long as it is used in a normal secondary battery.

[Method for producing electrode for nonaqueous electrolyte secondary battery]
The electrode for a non-aqueous electrolyte secondary battery of the present invention has a metal skeleton having a three-dimensional network structure, has pores between the metal skeletons, and an Al ₃ Ti compound is dispersed in the metal skeleton. The pores of the aluminum porous sintered body are filled with a slurry containing an active material, a conductive additive and a Li ion conductive material, dried, and then rolled.

  The aluminum porous sintered body can be manufactured as follows.

  First, an aluminum mixed raw material powder is prepared by mixing titanium powder and / or titanium hydride powder 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). The 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 630 (° C.) ≦ heating and firing temperature (non-oxidizing atmosphere) T) <660 (° C.) and heat firing (sintering process).

  In this aluminum mixed raw material powder preparation step, an average particle diameter of the aluminum powder is preferably 2 to 200 μm, more preferably 2 to 100 μm, and still more preferably 7 μm to 40 μm. Here, the average particle diameter is measured by a laser diffraction method.

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

  The average particle size of titanium hydride is preferably 0.1 (μm) ≦ r ≦ 30 (μm), more preferably 4 (μm) ≦ r ≦ 20 (μm). This is because if the average particle size of titanium hydride is smaller than 0.1 μm, spontaneous ignition may occur, and if it exceeds 30 μm, desired strength cannot be obtained in the sintered body. The blending amount of titanium hydride is preferably 0.1 (mass%) ≦ W ≦ 20 (mass%). If the amount is less than 0.1% by mass, the sintering becomes insufficient. On the other hand, if the blending ratio W of the sintering aid powder exceeds 20% by mass, the sintered body becomes brittle and the desired porous sintered body is obtained. It is because it becomes impossible to obtain.

  Next, in the viscous composition preparation step, a water-soluble resin binder, a plasticizer, distilled water, and a surfactant are added to the aluminum mixed raw material powder, respectively.

  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, after the viscous composition is applied to the belt-like polyethylene sheet foil by a doctor blade method, a slurry extrusion method or a screen printing method so as to have a thickness of 0.05 mm to 5 mm. Then, the ambient temperature and humidity are controlled for a certain period of time to size the bubbles, and then dried at a temperature of 70 ° C. in an air dryer. Here, from the viewpoint of mechanical strength, the thickness of the aluminum foil is preferably 10 μm or more and less than 50 μm, and more preferably 15 μm or more and 25 μm or less.

  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. As a result, debinding that volatilizes and / or decomposes the binder solution of the water-soluble resin binder component, plasticizer component, distilled water, and surfactant in the pre-sintered molded body is performed, and hydrogen is used as the sintering aid powder. When titanium fluoride is used, dehydrogenation is performed.

  Thereafter, the pre-sintered shaped body after temporary firing is heated and fired at 630 (° C.) ≦ heating and firing temperature (T) <660 (° C.) to obtain an aluminum composite.

  In addition, in order to suppress the growth of the oxide film on the surface of an aluminum particle, the surface of a titanium particle, and the surface of a nickel particle, it is necessary to perform the heat baking in a sintering process in a non-oxidizing atmosphere. However, if the heating temperature is 400 ° C. or lower and maintained for about 30 minutes, the oxide film on the aluminum particle surface, titanium particle surface and nickel particle surface does not grow much even when heated in air. The formed compact may be heated and held at 300 ° C. to 400 ° C. in air for about 10 minutes to remove the binder, and then heated and 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, does not measure the reaction temperature of the aluminum mixed raw material powder, but means the holding temperature around the aluminum mixed raw material powder. .

The aluminum porous sintered body of the aluminum composite obtained in this manner has a metal skeleton with a three-dimensional network structure, has pores between the metal skeletons, and is almost uniformly in the metal sintered body. The Al ₃ Ti compound is dispersed. 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.

  Next, the manufacturing method of a collector provided with an aluminum porous sintered body and an aluminum foil will be described. At this time, the viscous composition is applied onto a strip-shaped aluminum foil, and the dried viscous composition is cut into a desired shape together with the aluminum foil. be able to. The thickness of the aluminum foil is preferably 10 μm or more and less than 50 μm, and more preferably 15 μm or more and 25 μm or less from the viewpoint of mechanical strength.

  Next, the manufacturing method of a collector provided with an aluminum porous sintered body and an aluminum plate will be described. At this time, it is preferable to further add nickel to the sintering aid containing titanium.

  The sintering aid preferably contains 0.1 to 20 parts by mass of titanium with respect to a total of 100 parts by mass of aluminum, nickel and titanium, and the sintering aid containing nickel is aluminum, nickel and titanium. It is preferable that 0.2-2 mass parts of nickel is included with respect to 100 mass parts in total. Here, the average particle diameter of the nickel powder is desirably smaller than the average particle diameter of aluminum. For example, the average particle diameter is preferably 0.5 μm to 3 μm, more preferably 0.8 μm to 2 μm. If the amount of nickel powder is too small, the effect of promoting the sintering will not be exhibited. On the other hand, if the amount is too large, coarse particles of visible droplet spherical aluminum having a diameter of 0.5 mm or more are generated in the sintered body. Therefore, the blending amount of nickel powder is preferably 0.2 to 2 parts by mass, more preferably 0.4 to 1.4 parts by mass.

  In the next pre-sintering step, after applying the viscous composition to the strip-shaped aluminum foil by a doctor blade method, a slurry extrusion method or a screen printing method so as to have a thickness of 0.05 mm to 5 mm, Ambient temperature and humidity are controlled for a certain period of time to size the bubbles and then dried at 70 ° C. in an air dryer. The preferable thickness of the aluminum foil here is as described above.

  And the viscous composition after drying is cut out to desired shape with aluminum foil, and the aluminum foil side is mounted on the aluminum plate of desired shape, and a pre-sintered molded object is obtained. By making aluminum foil exist on an aluminum plate, when aluminum mixed raw material powder shrink | contracts at the time of sintering, aluminum foil can be slid on an aluminum plate and the crack of an aluminum porous sintered compact can be prevented. The sintering process is the same as that of the porous aluminum sintered body.

Next, a slurry containing an active material, a conductive assistant and a Li ion conductive material, and optionally a binder, can be obtained, for example, as follows. First, after an active material, a conductive additive, a Li ion conductive material, and the like are uniformly mixed, an organic solvent is added to form a slurry. Alternatively, after dispersing the conductive assistant in an organic solvent, an active material, a Li ion conductive material, or the like is added, or the binder is dissolved or uniformly dispersed in an organic solvent. There are methods such as mixing an auxiliary agent and a Li ion conductive substance to form a slurry, but there is no particular limitation. 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. When the Li ion conductive material contains an electrolyte salt such as LiPF ₆ , first, a slurry containing an active material, a conductive auxiliary agent and a binder is prepared, applied and dried, and then the Li ion conductive material is added. A slurry impregnation method is also preferred.

  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 between the porous aluminum sintered body and the active material and the Li ion conductive material is measured. When the mass ratio of the active material and the Li ion conductive material is low, Drying can be repeated to achieve the desired amount. On the other hand, when the mass ratio of the active material and the Li ion conductive material 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 conductive additive, and a Li ion conductive material is rolled to obtain a nonaqueous electrolyte secondary battery electrode. 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. When the Li ion conductive material contains an electrolyte salt such as LiPF ₆ , the steps from slurry production to production of the nonaqueous electrolyte secondary battery are the same as the glove box or dry room substituted with inert gas. It is preferable to carry out within.

  The electrode for a non-aqueous electrolyte secondary battery of the present invention is very effectively used for a high-output and highly reliable non-aqueous electrolyte secondary battery.

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

[Production of current collector 1 made of aluminum porous 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 is placed on an alumina setter with zirconia bedding and pre-fired (debindered) in an argon stream, then heat-fired and porous aluminum porous fired. A consolidated current collector 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 a current collector 1. The thickness of the obtained current collector 1 was 1.2 mm. As a result of observing the current collector 1 by X-ray diffraction, Al and an Al ₃ Ti compound were confirmed.

  Next, the aluminum porous sintered body 1 was roll-rolled at a reduction rate of 20%, and it was confirmed silently that there was no crack.

[Production of current collector 2 provided with an aluminum porous sintered body and aluminum foil]
The viscous composition was stretched and applied on an aluminum foil coated with a release agent by the doctor blade method, and the dried viscous composition was cut into a circle with a diameter of 100 mm together with the aluminum foil before sintering. A current collector 2 was produced in the same manner as the current collector 1 except that a molded body was obtained.

[Production of current collector 3 provided with an aluminum porous sintered body and an aluminum plate]
First, an aluminum powder having an average particle diameter of 24 μm (including impurities: Fe: 0.15 mass%, Si: 0.05 mass% and Ni: 0.01 mass%), and nickel powder having an average particle diameter of 1 μm The titanium hydride powder having an average particle diameter of 9.1 μm is mixed in a total of 500 g so that the mass ratio of the aluminum powder, the nickel powder and the titanium hydride powder is 94: 1: 5 to prepare an aluminum mixed raw material powder. did.

  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 an aluminum foil having a thickness of 20 μm by a 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 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 cut out to the rectangle of 50 mm x 70 mm with aluminum foil, and it mounted on the aluminum plate of thickness: 0.5 mm and 60 mm x 90 mm, and obtained the compact before sintering.

The pre-sintered compact was calcined (debindered) in an argon stream atmosphere and then heated and calcined to obtain a current collector 3. Debinding was performed at 520 ° C. for 30 minutes. Heating and baking were performed at 650 ° C. for 30 minutes in an argon atmosphere to obtain a current collector 3. In the obtained current collector 3, the aluminum porous body portion was sintered and contracted to 45 mm × 63 mm and joined to the aluminum plate, and the total thickness of the aluminum porous body joined portion was 1.2 mm. As a result of observing the aluminum porous sintered body portion of the current collector 3 by X-ray diffraction, Al and an Al ₃ Ti compound were confirmed. FIG. 1 shows an SEM photograph of the current collector 1 obtained, and FIGS. 2 and 3 show partially enlarged photographs thereof, respectively.

[Manufacture of electrodes for non-aqueous electrolyte secondary batteries]
Example 1

Lithium cobalt oxide (LiCoO ₂ ) powder as an active material, ketjen black (KB) as a conductive material, and polyvinylidene fluoride (PVDF) as a binder are mixed at a mass ratio of 80:10:10 in a total of 200 g. A positive electrode agent was prepared, and 162 g of N-methyl-2pyrrolidone as a solvent was mixed with the positive electrode agent to prepare a positive electrode active material slurry. Next, after dissolving 40 g of vinylidene fluoride-hexafluoropropylene copolymer (manufactured by Elf Atchem, Kynar 2801: containing 12 wt% hexafluoropropylene) in 200 g of dimethyl carbonate at 60 ° C., 1M LiPF ₆ / EC + PC (1: 1 ( 80 g of the nonaqueous electrolyte of volume ratio)) was mixed with stirring to prepare a Li ion conductive material slurry.

  Next, the produced current collector 1 is dipped in this positive electrode active material slurry for 10 minutes, taken out and dried, then dipped in Li ion conductive material slurry for 10 minutes, taken out and dried, and then rolled. Thus, a positive electrode of the lithium ion battery of Example 1 having a thickness of 0.5 mm was produced. Here, the current collector 1 is immersed in the Li ion conductive material slurry, dried, and before rolling, the Li ion conductive material slurry adhering to the surface of the current collector 1 is wiped off to obtain almost the entire amount of active material, The conductive assistant and the Li ion conductive substance were included in the pores of the current collector 1.

(Examples 2 and 3)
Example 2 was the same as Example 1 except that the current collector 2 was used instead of the current collector 1, and Example 3 was the same except that the current collector 3 was used instead of the current collector 1. In the same manner as in Example 1, a positive electrode of a lithium ion battery was performed. In all of Examples 2 and 3, the aluminum porous sintered body side of the current collector was immersed in the positive electrode active material slurry and the Li ion conductive material slurry.

(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 is immersed in the positive electrode active material slurry prepared in Example 1 for 10 minutes, taken out, dried, and then rolled to form a positive electrode of the lithium ion battery of Conventional Example 1 having a thickness of 0.5 mm. Produced.

[Performance test of electrode for non-aqueous electrolyte secondary battery]
(Discharge capacity test)
A test cell of a nonaqueous electrolyte secondary battery was produced. FIG. 6 shows a schematic diagram of the configuration of the test cell used.

  As the negative electrode 11, foil-like lithium metal (thickness: 0.5mm) was cut into a width of 30mm and a length of 40mm, and a negative electrode current collecting tab 11a made of nickel was welded.

  Next, the positive electrode was cut into a width of 30 mm and a length of 40 mm to form a positive electrode 10, and an aluminum positive electrode current collecting tab 10 a was welded to the aluminum foil of the aluminum composite of the positive electrode 10. Further, as the separator 12, a polypropylene microporous membrane (thickness: 20 μm) separator 12 was cut into a width: 32 mm and a length: 42 mm. These were laminated in order of the negative electrode current collection tab 11a, the negative electrode 11, the separator 12, the positive electrode 10, and the positive electrode current collection tab 10a, and the laminated body was produced.

  The welded portions 13c on the three sides of the pair of aluminum laminate films 13a and 13b, which were cut to a size that can accommodate the laminated body, were heat-sealed to obtain an exterior body 13.

In an inert atmosphere, the laminate is inserted through the opening of the outer package 13, and the laminate is accommodated in the outer package 13, and 1M LiPF ₆ / EC + PC (1: 1 (volume ratio)) non-water After injecting the electrolyte, the opening of the outer package 13 was heat sealed and sealed to prepare a test cell.

  The test cell was discharged at a discharge rate of 2C and a discharge voltage of 4.2 to 2.8V. Table 1 shows these results.

(Reliability test)
The above test cell was charged / discharged at a rate of 2C (45 minutes for CVCC charging) and charged / discharged voltage: 2.8 to 4.2V, with “charging → rest: 15 minutes → discharge → rest: 15 minutes”. A cycle test was performed as one cycle. Table 1 shows the results of the discharge capacity after 100 cycles. Further, [“discharge capacity after 100 cycles” / “initial discharge capacity”] was defined as a capacity maintenance rate (unit: “%”). Table 1 shows the results of the capacity retention rate. Moreover, the presence or absence of the swelling of the test cell after a 100 cycle test was observed visually. Table 1 shows these results.

  As can be seen from Table 1, the test cells of Examples 1 to 3 have a high output charge / discharge rate: the capacity retention rate after 100 cycles at 2C is 93% or more, no swelling, and high reliability. It was. On the other hand, the test cell of Conventional Example 1 had a low capacity retention rate of about 78% after 100 cycles, and swollen, and the reliability was not high.

  As described above, the positive electrode for a non-aqueous electrolyte secondary battery of the present invention can produce a high-output and highly reliable non-aqueous electrolyte secondary battery.

DESCRIPTION OF SYMBOLS 1 Aluminum porous sintered body 2 Active material, conductive support agent, binder, and Li ion conductive material layer 3 Pore 10 Positive electrode 10a Positive electrode current collection tab 11 Negative electrode 11a Negative electrode current collection tab 12 Separator 13 Exterior body 13a, 13b Aluminum Laminate film 13c welded part

Claims (5)

A current collector comprising an aluminum porous sintered body, and a positive electrode for a secondary battery comprising an active material, a conductive additive and a Li ion conductive material in the pores of the aluminum porous sintered body, wherein the aluminum The porous sintered body is obtained by non-pressure sintering of aluminum particles having an average particle diameter of 7 to 40 μm and titanium hydride of 0.1 to 30 μm . A metal skeleton having a three-dimensional network structure, vacancies between the metal skeletons, pores in the metal skeleton itself, and an Al ₃ Ti compound dispersed in the metal skeleton A positive electrode for a non-aqueous electrolyte secondary battery.   The positive electrode for a nonaqueous electrolyte secondary battery according to claim 1, wherein the current collector further comprises an aluminum foil or an aluminum plate.   The positive electrode for a nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein the aluminum porous sintered 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 positive electrode for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the Li ion conductive substance is a polymer gel electrolyte or a solid electrolyte.   The nonaqueous electrolyte secondary battery containing the positive electrode for nonaqueous electrolyte secondary batteries of any one of Claims 1-4.