JPH09199136A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery having electrodes excellent in the adhesiveness between a paste and a current collector and the permeability of a nonaqueous electrolyte by forming the current collector of a positive electrode into a structure three-dimensionally arranged with hollow metal fibers. SOLUTION: The positive electrode of a nonaqueous electrolyte secondary battery is constituted of a positive electrode current collector 1 and a positive electrode layer 2 carried by the current collector 1, and the negative electrode is constituted of a negative electrode current collector 3 and a negative electrode layer 4 carried by the current collector 3. A solid polymer electrolyte layer 5 is inserted between the positive electrode layer 2 and the negative electrode layer 4. The current collector 1 of the positive electrode of this battery is formed into a structure three-dimensionally arranged with hollow metal fibers, or a metal film layer formed on a resin core material and the surface of the core material is formed into a structure three-dimensionally arranged with metal fibers. The hollow metal fibers are made of one or more kinds selected from titanium and aluminum. The rate of hole area of the current collector 1 of the positive electrode is preferably set to about 25-55%.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte secondary battery having an improved current collector.

[0002]

2. Description of the Related Art In recent years, with the development of electronic equipment, there has been a demand for the development of a secondary battery that is small, lightweight, has a high energy density, and can be repeatedly charged and discharged. As such a secondary battery, a negative electrode using lithium or a lithium alloy as an active material, and a suspension containing an active material of an oxide such as molybdenum, vanadium, titanium, or niobium, a sulfide, or a selenide is applied. A non-aqueous electrolyte secondary battery including a positive electrode made of a current collector and a non-aqueous electrolytic solution is known.

However, a secondary battery provided with a negative electrode using lithium or a lithium alloy as an active material has a problem of short charge / discharge cycle life because dendrite of lithium is generated in the negative electrode when the charge / discharge cycle is repeated. .

From the above, a suspension containing a carbonaceous material that absorbs and releases lithium ions, such as coke, graphite, carbon fiber, a resin fired body, and pyrolysis vapor-phase carbon, was applied to the negative electrode. A non-aqueous electrolyte secondary battery using a current collector has been proposed. In the secondary battery, the deterioration of the negative electrode characteristics due to dendrite deposition can be improved, so that the battery life and safety can be improved.

Further, as a polymer electrolyte secondary battery which is an example of a non-aqueous electrolyte secondary battery, US Pat.
No. 6,318 discloses a rechargeable lithium intercalation battery having a hybrid polymer electrolyte to which flexibility has been added by adding a polymer to a positive electrode, a negative electrode and an electrolyte layer. In such a polymer electrolyte secondary battery, a positive electrode having a structure in which a positive electrode layer containing an active material, a non-aqueous electrolytic solution, and a polymer holding the electrolytic solution is supported on a positive electrode current collector, and can absorb and release lithium ions. A negative electrode having a structure in which a negative electrode layer having an active material, a non-aqueous electrolytic solution and a polymer holding the electrolytic solution is supported on a negative electrode current collector, and is interposed between the positive electrode layer and the negative electrode layer, and a non-aqueous It is composed of an electrolytic solution and a solid polymer electrolyte layer having a polymer holding the electrolytic solution.

In these non-aqueous electrolyte secondary batteries,
A metal foil of aluminum or copper, a punched metal, or an expanded metal is used as a current collector carrying a suspension containing an active material (carbonaceous material) or an electrode layer containing the active material. However, since such a current collector has low adhesion to the suspension or the electrode layer, they are separated during repeated charging / discharging, impedance is increased, and capacity is lowered, resulting in a cycle. There is a problem that the life is shortened. Further, when the metal foil is used,
Since the permeability of the non-aqueous electrolyte is poor, there is a problem that sufficient ionic conductivity cannot be ensured and cycle characteristics and self-discharge characteristics deteriorate. On the other hand, when the punched metal or expanded metal is used, there is a problem that the current collection efficiency of the active material filled in the opening is located in the center of the opening, and is poor. Further, since the polymer electrolyte secondary battery has a thin film structure and the thickness of the current collector is very thin, the strength of the current collector is reduced when the punched metal or expanded metal is used. For this reason, it is difficult to handle the electrode layer when it is carried on the current collector by long coating, and the shape of the opening portion is easily deformed by pulling or bending, so that the electrode layer filled in the opening portion is opened. There is a problem in that it easily falls from the hole.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to improve the current collector by providing a non-aqueous electrolyte provided with an electrode in which the adhesion between the paste and the current collector and the permeability of the non-aqueous electrolyte are improved. It is to provide a secondary battery.

[0008]

A non-aqueous electrolyte secondary battery according to the present invention comprises a positive electrode having a structure in which a paste containing an active material is carried on a current collector, a negative electrode and a non-aqueous electrolyte. In the water electrolyte secondary battery, the current collector of the positive electrode has a structure in which hollow metal fibers are three-dimensionally arranged.

The non-aqueous electrolyte secondary battery according to the present invention is a non-aqueous electrolyte secondary battery including a positive electrode having a structure in which a paste containing an active material is supported on a current collector, a negative electrode, and a non-aqueous electrolyte. The current collector of the positive electrode has a structure in which a resin core material and metal fibers having a metal coating layer formed on the surface of the core material are three-dimensionally arranged.

The non-aqueous electrolyte secondary battery according to the present invention is a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode having a structure in which a paste containing an active material is supported on a current collector, and a non-aqueous electrolyte. The current collector of the negative electrode is characterized by having a structure in which hollow metal fibers are three-dimensionally arranged.

The non-aqueous electrolyte secondary battery according to the present invention is a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode having a structure in which a paste containing an active material is supported on a current collector, and a non-aqueous electrolyte. The negative electrode current collector has a structure in which metal fibers having a resin core material and a metal coating layer formed on the surface of the core material are three-dimensionally arranged.

A non-aqueous electrolyte secondary battery according to the present invention has a positive electrode having a structure in which a paste containing an active material is carried on a current collector, and a structure in which a paste containing an active material is carried on a current collector. In a non-aqueous electrolyte secondary battery including a negative electrode and a non-aqueous electrolyte, the current collectors of the positive electrode and the negative electrode are characterized in that hollow metal fibers have a three-dimensionally arranged structure. .

The non-aqueous electrolyte secondary battery according to the present invention has a positive electrode having a structure in which a paste containing an active material is carried on a current collector, and a structure in which a paste containing an active material is carried on a current collector. In the non-aqueous electrolyte secondary battery having a negative electrode and a non-aqueous electrolyte, the current collector of the positive electrode and the negative electrode, a metal core having a resin core material and a metal coating layer formed on the core material surface It is characterized by having a three-dimensionally arranged structure.

The non-aqueous electrolyte secondary battery according to the present invention has a positive electrode having a structure in which a paste containing an active material is carried on a current collector, and a structure in which a paste containing an active material is carried on a current collector. Negative electrode, in a non-aqueous electrolyte secondary battery comprising a non-aqueous electrolyte, the positive electrode current collector has a structure in which hollow metal fibers are three-dimensionally arranged, and the negative electrode current collector, It is characterized in that it has a structure in which a resin core material and metal fibers having a metal coating layer formed on the surface of the core material are three-dimensionally arranged.

The non-aqueous electrolyte secondary battery according to the present invention has a positive electrode having a structure in which a paste containing an active material is carried on a current collector, and a structure in which a paste containing an active material is carried on a current collector. In a non-aqueous electrolyte secondary battery including a negative electrode and a non-aqueous electrolyte, the current collector of the positive electrode is a three-dimensional metal fiber having a resin core material and a metal coating layer formed on the core material surface. And the negative electrode current collector has a structure in which hollow metal fibers are three-dimensionally arranged.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An example of a non-aqueous electrolyte secondary battery (polymer electrolyte secondary battery) according to the present invention will be described below with reference to FIG. The positive electrode is the positive electrode current collector 1 and this current collector 1
It is composed of the positive electrode layer 2 carried on. The negative electrode is composed of a negative electrode current collector 3 and a negative electrode layer 4 carried on the current collector 3. The solid polymer electrolyte layer 5 is interposed between the positive electrode layer 2 and the negative electrode layer 4.

Next, the solid polymer electrolyte layer 5, the positive electrode and the negative electrode will be described. 1) Solid Polymer Electrolyte Layer 5 This polymer electrolyte layer 5 is a sheet containing a non-aqueous electrolytic solution and a polymer holding the electrolytic solution.

The non-aqueous electrolyte is prepared by dissolving an electrolyte in a non-aqueous solvent. As the non-aqueous solvent,
Ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DE
C), ethyl methyl carbonate (EMC), γ-butyrolactone (γ-BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (TH
F), 2-methyltetrahydrofuran, etc. can be mentioned. The non-aqueous solvent may be used alone or in combination of two or more.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ) and lithium hexafluorophosphate (L
iPF _6), boric tetrafluoride lithium (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium trifluoromethanesulfonate (LiCF ₃ SO _3), bis (trifluoromethylsulfonyl) imide lithium [LiN
(CF ₃ SO ₃ ) ₂ ].

The amount of the electrolyte dissolved in the non-aqueous solvent is desirably 0.2 mol / l to 2 mol / l. As the polymer that holds the non-aqueous electrolyte, for example, a polyethylene oxide derivative, a polypropylene oxide derivative, a polymer containing the derivative, a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), or the like is used. You can Particularly, it is preferable to use the above-mentioned copolymer from the viewpoint of increasing the impregnation amount of the non-aqueous electrolyte. In addition, in the copolymer, VdF contributes to the improvement of mechanical strength in the skeleton of the copolymer, and HFP is incorporated in the copolymer in an amorphous state to retain the non-aqueous electrolyte and lithium. It functions as an ion permeation part. The copolymerization ratio of the HFP depends on the method of synthesizing the copolymer, but is usually at most about 20% by weight.

The solid electrolyte layer 5 may be irradiated with an electron beam or the like to crosslink the molecules of the polymer holding the electrolytic solution. The solid electrolyte layer 5 can be produced, for example, by the method described below.

1) A solution of a polymer that holds the non-aqueous electrolyte is prepared, a plasticizer such as DBP (dibutyl phthalate) is added to the solution, and a film is formed and dried. A polymer electrolyte layer is prepared by immersing the electrolytic solution in the electrolytic solution so as to hold the electrolytic solution in the polymer and replacing the plasticizer with the electrolytic solution to impregnate the electrolytic solution.

2) A solution of a polymer which holds the non-aqueous electrolyte is prepared, a plasticizer such as DBP (dibutyl phthalate) is added to the solution, and a film is formed and dried, and then the plasticizer is added. It is removed by extraction with a solvent such as ethanol and impregnated with a non-aqueous electrolyte to form a polymer electrolyte layer.

3) A polymer solution holding the non-aqueous electrolyte solution is prepared, and the solution is formed into a film, dried, and then impregnated with the non-aqueous electrolyte solution to form a polymer electrolyte layer.
In the methods (1) and (2), the plasticizer is added for the purpose of improving mechanical characteristics such as strength of the solid electrolyte layer and improving the impregnation amount of the electrolytic solution to improve charge / discharge characteristics. After the addition of the plasticizer, a film is formed, and the polymer electrolyte layer is impregnated with the nonaqueous electrolyte so that the plasticizer is replaced with the nonaqueous electrolyte, whereby the impregnation amount of the electrolyte can be increased. .

In the production methods (1) to (3), the impregnation of the electrolytic solution (including the removal of the plasticizer in the case of adding the plasticizer) is performed after forming the laminated structure shown in FIG. But good. 2) Positive Electrode This positive electrode is composed of a current collector 1 carrying a positive electrode layer 2 containing an active material, a conductive material, a non-aqueous electrolytic solution and a polymer holding the electrolytic solution.

As the active material, various oxides (for example, lithium-manganese composite oxide such as LiMn ₂ O ₄ ;
Manganese dioxide, lithium-containing nickel oxide such as LiNiO ₂ , lithium-containing cobalt oxide such as LiCoO ₂ , lithium-containing nickel cobalt oxide, amorphous vanadium pentoxide containing lithium, etc.)
And chalcogen compounds (for example, titanium disulfide, molybdenum disulfide, and the like). Among them, it is preferable to use a lithium manganese composite oxide, a lithium-containing cobalt oxide, and a lithium-containing nickel oxide.

Examples of the conductive material include artificial graphite, carbon black (for example, acetylene black, etc.), nickel powder and the like. As the non-aqueous electrolyte and the polymer, the same ones as those described in the solid polymer electrolyte layer described above are used.

As the current collector 1, the one shown in (a) or (b) is used. (A) A current collector having a structure in which hollow metal fibers are three-dimensionally arranged. The hollow metal fiber may be formed of a single metal, but may have a multi-layer structure in which a plurality of metal layers are concentrically arranged. Such hollow metal fibers can be formed from at least one selected from titanium, aluminum and the like.

The porosity of the current collector is preferably 25 to 55%. This is due to the following reasons. When the porosity is less than 25%, the adhesion between the current collector and the positive electrode layer and the permeability of the non-aqueous electrolyte into the positive electrode layer may be reduced. On the other hand, if the porosity exceeds 55%, the strength of the current collector and the adhesion between the current collector and the positive electrode layer may be reduced. A more preferable porosity is in the range of 35 to 50%.

The current collector can be produced, for example, by coating a non-woven fabric made of polymer fibers with a metal layer by plating or the like, and then firing this to burn out the polymer fibers.

The non-woven fabric is, for example, polyethylene fiber,
It can be formed from polymer fibers such as polyolefin fibers such as polypropylene fibers, polyester fibers, polyvinyl chloride fibers, polyacrylonitrile fibers and polyamide fibers.

(B) A current collector having a structure in which metal fibers composed of a resin core material and a metal coating layer formed on the surface of the core material are three-dimensionally arranged. The core material, for example, polyethylene resin, polyolefin resin such as polypropylene resin, polyester resin, polyvinyl chloride resin,
It can be formed from polyacrylonitrile resin, polyamide resin, or the like.

The coating layer may be formed of a single metal, but may have a multi-layer structure in which a plurality of metal layers are concentrically arranged. Such a coating layer can be formed from at least one selected from titanium, aluminum, and the like.

The porosity of the current collector is preferably 25 to 60%. This is due to the following reasons. When the porosity is less than 25%, the adhesion between the current collector and the positive electrode layer and the permeability of the non-aqueous electrolyte into the positive electrode layer may be reduced. On the other hand, if the porosity exceeds 60%, the strength of the current collector and the adhesion between the current collector and the positive electrode layer may deteriorate. A more preferable porosity is in the range of 35 to 50%.

The current collector can be produced, for example, by coating a non-woven fabric made of the resin with a metal layer by plating or the like. The positive electrode can be produced, for example, by the method described below.

1) A solution of a polymer holding the non-aqueous electrolytic solution is prepared, and a plasticizer such as DBP (dibutyl phthalate), the active material and the conductive material are added to the solution, and then these are mixed. After forming the positive electrode layer by forming a film, the positive electrode layer and the current collector are bonded by, for example, thermocompression bonding. By impregnating the positive electrode layer with the electrolytic solution by substituting the electrolytic solution with the plasticizer in the positive electrode layer while holding the electrolytic solution in the polymer by immersing it in a non-aqueous electrolytic solution, or After removing the plasticizer in the positive electrode layer by extracting it with a solvent such as ethanol, the positive electrode layer is impregnated with a non-aqueous electrolytic solution to prepare a positive electrode.

2) A solution of a polymer holding the non-aqueous electrolyte is prepared, and a plasticizer such as DBP (dibutyl phthalate), the active material and the conductive material are added to the solution, and then these are mixed. A paste for positive electrode is prepared. The positive electrode paste is applied to the current collector and then dried. By impregnating the positive electrode layer with the electrolytic solution by substituting the electrolytic solution with the plasticizer in the positive electrode layer while holding the electrolytic solution in the polymer by immersing it in a non-aqueous electrolytic solution, or After removing the plasticizer in the positive electrode layer by extracting it with a solvent such as ethanol, the positive electrode layer is impregnated with a non-aqueous electrolytic solution to prepare a positive electrode.

3) A positive electrode layer was prepared by preparing a solution of a polymer holding the non-aqueous electrolytic solution, adding the active material and the conductive material to the solution, mixing them, and forming a film. After that, the positive electrode layer and the current collector are adhered to each other by, for example, thermocompression bonding, and a nonaqueous electrolytic solution is impregnated to produce a positive electrode.

4) A polymer solution holding the non-aqueous electrolyte is prepared, the active material and the conductive material are added to the solution, and then these are mixed to prepare a positive electrode paste. After applying the positive electrode paste to the current collector,
A positive electrode is manufactured by drying and impregnating with a non-aqueous electrolyte.

In the above methods (1) and (2), a plasticizer is added for the purpose of improving mechanical properties such as strength of the solid electrolyte layer and improving the amount of electrolyte impregnated to improve charge / discharge characteristics. To be done.

In the methods (1) to (4), the impregnation of the electrolytic solution (including the removal of the plasticizer when the plasticizer is added) is performed even after the above-mentioned laminated structure shown in FIG. 1 is formed. good. 3) Negative Electrode In this negative electrode, a negative electrode layer 4 containing an active material, a non-aqueous electrolytic solution, and a polymer holding the electrolytic solution is carried on a current collector 3.

Examples of the active material include a carbonaceous material that absorbs and releases lithium ions. As such a carbonaceous material, for example, an organic polymer compound (for example,
Phenolic resin, polyacrylonitrile, cellulose, etc.) obtained by baking, coke,
Examples thereof include those obtained by firing pitch, and carbonaceous materials represented by artificial graphite, natural graphite, and the like. Among them, in an atmosphere of an inert gas such as an argon gas and a nitrogen gas, 500 ° C. to 3000 ° C.
It is preferable to use a carbonaceous material obtained by firing the organic polymer compound at a temperature of ° C. under normal pressure or reduced pressure.

As the non-aqueous electrolyte and the polymer, the same ones as those described in the solid polymer electrolyte layer described above are used. The negative electrode layer is allowed to contain conductive materials such as artificial graphite, natural graphite, carbon black, acetylene black, Ketjen black, nickel powder, polyphenylene derivatives, and fillers such as olefin polymers and carbon fibers.

As the current collector 1, the one shown in (A) or (B) is used. (A) A current collector having a structure in which hollow metal fibers are three-dimensionally arranged. The hollow metal fiber may be formed of a single metal, but may have a multi-layer structure in which a plurality of metal layers are concentrically arranged. Such hollow metal fibers can be formed from at least one kind selected from nickel, copper and the like.

The porosity of the current collector is preferably 25 to 60%. This is due to the following reasons. When the porosity is less than 25%, the adhesion between the current collector and the negative electrode layer and the permeability of the non-aqueous electrolyte into the negative electrode layer may be reduced. On the other hand, if the porosity exceeds 60%, the strength of the current collector and the adhesion between the current collector and the negative electrode layer may be reduced. A more preferable porosity is in the range of 35 to 55%.

The current collector can be produced, for example, by coating a non-woven fabric made of polymer fibers with a metal layer by plating or the like, and then firing this to burn out the polymer fibers.

The non-woven fabric is, for example, polyethylene fiber,
It can be formed from polymer fibers such as polyolefin fibers such as polypropylene fibers, polyester fibers, polyvinyl chloride fibers, polyacrylonitrile fibers and polyamide fibers.

(B) A current collector having a structure in which metal fibers composed of a resin core material and a metal coating layer formed on the surface of the core material are three-dimensionally arranged. The core material, for example, polyethylene resin, polyolefin resin such as polypropylene resin, polyester resin, polyvinyl chloride resin,
It can be formed from polyacrylonitrile resin, polyamide resin, or the like.

The coating layer may be formed of a single metal, but may have a multi-layer structure in which a plurality of metal layers are concentrically arranged. Such a coating layer can be formed from at least one selected from nickel, copper and the like.

The porosity of the current collector is preferably 25 to 65%. This is due to the following reasons. When the porosity is less than 25%, the adhesion between the current collector and the negative electrode layer and the permeability of the non-aqueous electrolyte into the negative electrode layer may be reduced. On the other hand, when the porosity exceeds 65%, the strength of the current collector and the adhesion between the current collector and the negative electrode layer may be deteriorated. A more preferable porosity is in the range of 35 to 55%.

The current collector can be produced, for example, by coating a non-woven fabric made of the resin with a metal layer by plating or the like. The negative electrode can be produced, for example, by the method described below.

1) A solution of a polymer holding the non-aqueous electrolyte is prepared, a plasticizer such as DBP (dibutyl phthalate) and the active material are added to the solution, and then these are mixed to form a film. After producing the negative electrode layer by
The negative electrode layer and the current collector are bonded by, for example, thermocompression bonding. By impregnating the negative electrode layer with the electrolytic solution by substituting the electrolytic solution with the plasticizer in the negative electrode layer while holding the electrolytic solution in the polymer by immersing it in a non-aqueous electrolytic solution, or The plasticizer in the negative electrode layer is removed by extraction with a solvent such as ethanol, and then impregnated with a non-aqueous electrolytic solution to produce a negative electrode.

2) A solution of a polymer holding the non-aqueous electrolyte is prepared, a plasticizer such as DBP (dibutyl phthalate) and the active material are added to the solution, and then these are mixed to prepare a negative electrode paste. To prepare. The negative electrode paste is applied to the current collector and then dried. By impregnating the negative electrode layer with the electrolytic solution by substituting the electrolytic solution with the plasticizer in the negative electrode layer while holding the electrolytic solution in the polymer by immersing it in a non-aqueous electrolytic solution, or The plasticizer in the negative electrode layer is removed by extraction with a solvent such as ethanol, and then impregnated with a non-aqueous electrolytic solution to produce a negative electrode.

3) A solution of a polymer holding the non-aqueous electrolyte is prepared, the active material is added to the solution, these are mixed and a film is formed to form a negative electrode layer, and then the negative electrode is prepared. The layer and the current collector are bonded to each other by, for example, thermocompression bonding. A negative electrode is produced by impregnating this with a non-aqueous electrolyte.

4) A solution of a polymer that holds the non-aqueous electrolyte is prepared, the active material is added to the solution, and then these are mixed to prepare a negative electrode paste. The negative electrode paste is applied to the current collector, dried, and then impregnated with a non-aqueous electrolyte to form a negative electrode.

In the above methods (1) and (2), a plasticizer is added for the purpose of improving mechanical characteristics such as strength of the solid electrolyte layer and improving the amount of electrolyte impregnated to improve charge / discharge characteristics. To be done.

In the above methods (1) to (4), the impregnation of the electrolytic solution (including the removal of the plasticizer in the case of adding the plasticizer) can be performed even after the laminated structure shown in FIG. 1 is formed. good.

The positive electrode, the negative electrode and the polymer electrolyte layer can be laminated by the method described below. 1) These are laminated by interposing a polymer electrolyte layer between the positive electrode and the negative electrode. The laminate is stored in a container, a bag-shaped sheet or the like so that the positive electrode, the negative electrode and the electrolyte layer are kept in close contact with each other, and is used as a secondary battery. The positive electrode, the negative electrode, and the polymer electrolyte layer may be impregnated with the electrolytic solution before or after the lamination.

2) The laminate is formed by interposing a polymer electrolyte layer between the positive electrode and the negative electrode and adhering them by thermocompression bonding or the like. In the method (2), the temperature at which the thermocompression bonding is performed may be adjusted in consideration of the types and amounts of the polymer and the plasticizer added to the positive electrode, the negative electrode and the polymer electrolyte layer. When a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP) is used as the polymer holding the non-aqueous electrolyte, the temperature for performing the thermocompression bonding should be in the range of 120 to 150 ° C. Is preferred. Also,
When thermocompression bonding is performed, it is preferable to impregnate the positive electrode, the negative electrode, and the polymer electrolyte layer with the electrolytic solution after the lamination.

When the current collector shown in (a) or (b) above is used in the positive electrode, a copper foil is used instead of the one shown in (A) or (B) above as the current collector for the negative electrode. It is acceptable to use copper mesh, copper expanded metal, and copper punched metal.

When the current collector shown in (A) or (B) is used in the negative electrode, an aluminum foil is used as the current collector in the positive electrode instead of the current collector shown in (a) or (b). It is acceptable to use aluminum mesh, aluminum expanded metal, and aluminum punched metal.

Another example of the non-aqueous electrolyte secondary battery according to the present invention will be described. The non-aqueous electrolyte secondary battery has a structure in which an electrode group in which a separator is interposed between a positive electrode and a negative electrode and a non-aqueous electrolytic solution are housed in a closed container.

Next, the positive electrode, the negative electrode, the separator and the non-aqueous solvent will be described. (1) Positive Electrode This positive electrode is prepared, for example, by preparing a paste containing an active material, a conductive material, and a binder, applying the paste to a current collector, and then drying and pressing the paste.

As the active material and the conductive material,
The same thing as what was demonstrated by the polymer electrolyte secondary battery mentioned above can be mentioned. Examples of the binder include polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, polymethacrylic acid, polyacrylic acid salt, polymethacrylic acid salt, polyacrylic acid ester, polymethacrylic acid ester, and acrylic. Copolymer of either one of an acid or methacrylic acid and either an acrylic acid ester or a methacrylic acid ester, a copolymer of any one of an acrylic acid ester or a methacrylic acid ester and another monomer, Examples thereof include rubber polymers.

The current collector may be the same as that described for the positive electrode of the polymer electrolyte secondary battery described above. 2) Negative Electrode This negative electrode is prepared, for example, by preparing a paste containing an active material and a binder, applying the paste to a current collector, and then performing drying and pressure molding.

Examples of the active material include carbonaceous materials that absorb and release lithium ions. As such a carbonaceous material, the same materials as described for the negative electrode of the polymer electrolyte secondary battery described above can be mentioned.

As the binder, the same binder as described above for the positive electrode can be used. The current collector may be the same as that described for the negative electrode of the polymer electrolyte secondary battery described above.

The negative electrode contains artificial graphite, natural graphite, carbon black,
Conductive materials such as acetylene black, Ketjen black, nickel powder, and polyphenylene derivatives, and fillers such as olefin polymers and carbon fibers are allowed to be included. 3) Separator 4 Examples of the separator 4 include a polyolefin fiber nonwoven fabric and a polyolefin fiber porous membrane. As the polyolefin fiber, for example, polypropylene fiber, polyethylene fiber or the like can be used. 4) Non-aqueous electrolyte solution This electrolyte solution is prepared by dissolving an electrolyte in a non-aqueous solvent.

As the non-aqueous solvent and the electrolyte, the same ones as described for the polymer electrolyte secondary battery can be mentioned. In such a secondary battery, when the current collector shown in (a) or (b) is used in the positive electrode, the current collector in the negative electrode is replaced by the current collector shown in (A) or (B). It is permissible to use copper foil, copper mesh, copper expanded metal, or copper punched metal.

When the current collector shown in (A) or (B) is used in the negative electrode, an aluminum foil is used as the current collector of the positive electrode instead of the current collector shown in (a) or (b). It is acceptable to use aluminum mesh, aluminum expanded metal, and aluminum punched metal.

According to the present invention, in a non-aqueous electrolyte secondary battery using a positive electrode and / or a negative electrode having a structure in which a paste containing an active material is supported on a current collector, hollow metal fibers are used as the current collector. Having a three-dimensionally arranged structure, or having a core-sheath structure in which metal fibers having a resin core material and a metal coating layer formed on the surface of the core material are three-dimensionally arranged. To use. In other words,
A current collector having a structure in which hollow metal fibers (or the metal fibers having the core-sheath structure) are intertwined is used. Since such a current collector can improve the adhesiveness with the paste, it is possible to avoid the peeling of the paste as the charge / discharge cycle progresses. In particular, since aluminum used for the positive electrode current collector has poor adhesion to the paste, it is possible to significantly improve the paste adhesive strength of the positive electrode current collector mainly composed of aluminum by adopting the above-mentioned three-dimensional structure. You can

Since the current collector having the three-dimensional structure has a gap between the hollow metal fibers (or the core-sheath structure metal fibers), the non-aqueous electrolyte can be passed through quickly.
As a result, in the polymer electrolyte secondary battery, it was prepared when the non-aqueous electrolyte solution was impregnated into the battery having the laminated structure shown in FIG. 1 and the separator was interposed between the positive electrode and the negative electrode. In the non-aqueous electrolyte secondary battery having a structure in which the electrode group and the non-aqueous electrolytic solution are housed in a closed container, when the non-aqueous electrolytic solution is injected into the container in which the electrode group is housed, the positive electrode layer, the solid Permeation of the nonaqueous electrolytic solution into the battery constituent members such as the polymer electrolyte layer and the separator can be performed promptly without being blocked by the current collector, and a sufficient amount can be permeated.

In particular, by using the current collector in the polymer electrolyte secondary battery in which the positive electrode layer, the negative electrode layer, or the polymer electrolyte layer is produced by the method using the plasticizer, the current collector described above is located outside. The removal of the plasticizer in a battery not impregnated with the electrolyte having a laminated structure can be performed quickly and completely, and a sufficient amount of the non-aqueous electrolyte can be rapidly penetrated. It is possible to realize a secondary battery, which has a feature that the amount of impregnated electrolyte is increased, by a highly productive manufacturing method in which the positive electrode, the negative electrode and the polymer electrolyte layer are laminated and then impregnated with the electrolytic solution.

Further, since the current collector has high mechanical strength, it is improved in handleability and shape retention when the current collector is made thin so as to be applied to a battery having a thin film structure such as a polymer electrolyte secondary battery. can do. In addition, since the current collector has high conductivity, the current collection efficiency can be improved.

Accordingly, by using a current collector having a structure in which hollow metal fibers (or metal fibers having a core-sheath structure) are three-dimensionally arranged, the adhesion between the current collector and the paste and the battery constituent members are improved. Since the permeability of the electrolyte solution, the strength of the current collector, and the current collection efficiency can be improved, the charge / discharge cycle characteristics and self-discharge characteristics of the non-aqueous electrolyte secondary battery can be improved.

[0076]

Embodiments of the present invention will be described below in detail with reference to the drawings. Example <Preparation of Positive Electrode> Copolymer of vinylidene fluoride-hexafluoropropylene (VdF-HFP) in 20 g of acetone (manufactured by Erfatchem, trade name: KYNAR28)
No. 01, the copolymerization ratio VdF: HFP is 88:12) 2.8 g of powder was dissolved, 4.3 g of dibutyl phthalate (DBP) was added to this acetone solution, and the composition formula was LiCoO ₂ as an active material. 10.5 g of a lithium-containing cobalt oxide represented by (Nippon Heavy Chemical Industry Co., Ltd.) and 1.13 g of acetylene black as a conductive material were added and dispersed by mixing to obtain a positive electrode paste. The positive electrode paste was applied to the positive electrode current collector using a knife coater so that the paste had a rate of 2.5 mAh / cm ² and a coating speed of 1 m /
A positive electrode was prepared by applying the coating solution for min and drying the coating film with dry air.

As the positive electrode current collector, a core material made of polyester resin and metal fibers having a coating layer made of aluminum formed on the surface of the core material were entwined in a non-woven fabric and three-dimensionally arranged. The one having a structure was used. The current collector has a thickness of 30 μm and an opening ratio of 4
0%. <Fabrication of Negative Electrode> 2.0 g of a vinylidene fluoride-hexafluoropropylene copolymer of the same type as that used in the positive electrode layer was dissolved in 12 g of acetone to prepare an acetone solution, and then this acetone solution was added. After adding 3.12 g of dibutyl phthalate (DBP), mesophase pitch carbon fiber (made by Petka Co., Ltd.) as an active material.
A negative electrode paste was prepared by adding 7.37 g and mixing them. 2.5m of the negative electrode paste
A knife coater was used to apply Ah / cm ² to the negative electrode current collector under the same conditions as described above, and the coating film was dried with dry air to prepare a negative electrode.

The negative electrode current collector has a structure in which a core material made of polyester resin and a metal fiber having a copper coating layer formed on the surface of the core material are three-dimensionally arranged in a non-woven fabric intertwined with each other. Was used. The thickness of the current collector is 25 μm, and the open area ratio is 40%. <Preparation of solid polymer electrolyte layer> 2.0 g of a copolymer of vinylidene fluoride-hexafluoropropylene of the same kind as that used for the positive electrode layer was added to 10 g of acetone.
To prepare an acetone solution, and then 2.0 g of dibutyl phthalate (DBP) was added to the acetone solution and mixed to prepare an electrolyte layer paste. The paste was applied onto a smooth glass plate so that the film thickness after drying was 70 μm, and then dried in the same manner as the positive and negative electrodes, and peeled off from the glass plate to prepare a solid polymer electrolyte layer. <Preparation of Non-Aqueous Electrolyte> A non-aqueous solvent in which ethylene carbonate (EC) and dimethyl carbonate (DMC) are mixed at a volume ratio of 1: 1 and LiPF ₆ as an electrolyte has a concentration of 1 mol / l. Was dissolved as described above to prepare a non-aqueous electrolytic solution.

The obtained positive electrode and negative electrode were cut out into a size of 2 cm × 2 cm, and the solid polymer electrolyte layer was 2.25.
It was cut out into a size of cm × 2.25 cm. The polymer electrolyte layer was interposed between the positive electrode and the negative electrode, these were thermocompression bonded by a rigid roll heated to 130 ° C. and laminated as shown in FIG. 1 described above to obtain a battery before impregnation with an electrolytic solution. It was Comparative Example 1 An aluminum foil having a thickness of 20 μm was used as the positive electrode current collector, and a thickness of 10 μm was used as the negative electrode current collector.
A battery not impregnated with an electrolytic solution having the same configuration as in Example 1 except that the copper foil of No. 1 was used was produced. Comparative Example 2 As the positive electrode current collector, an expanded metal made of aluminum and having a thickness of 30 μm (mesh length center distance;
1.5 mm, mesh short direction center distance; 0.75 m
m, step size; 0.1 mm), and a copper expanded metal having a thickness of 30 μm as the negative electrode current collector (mesh long direction center distance; 1.5 mm, mesh short direction direction center distance; 0.75 mm , Step size; 0.05m
A battery not impregnated with an electrolytic solution having the same configuration as in Example 1 except that m) was used was prepared. Comparative Example 3 Punched metal made of aluminum with a thickness of 30 μm as the positive electrode current collector (hole diameter: 1.5 mm, open area ratio 40%)
And has a thickness of 20 μm as the negative electrode current collector.
Copper punched metal (hole diameter: 1.5 mm, opening rate: 4)
A battery not impregnated with an electrolytic solution having the same structure as in Example 1 except that 0%) was used was prepared.

Regarding the obtained batteries of Example 1 and Comparative Examples 1 to 3 which were not impregnated with the electrolytic solution, the DBP in the positive electrode, the negative electrode and the electrolyte layer constituting the battery by immersing in the non-aqueous electrolytic solution.
And the electrolytic solution is replaced and the polymer is impregnated with the electrolytic solution, and the impedance of the secondary battery after 10 minutes, 2 hours, and 1 week of immersion in the electrolytic solution and the remaining amount of DBP in the secondary battery ( The ratio to the charged amount) was measured, and the results are shown in Table 1 below.

The positive and negative electrodes of Example 1 and Comparative Examples 1 to 3 were each cut into a size of 1 cm × 10 cm, the peel strength of the positive and negative electrode layers of the current collector was measured, and the results are shown in Table 1 below. Shown in.

[0082]

[Table 1]

As is clear from Table 1, a positive electrode including a current collector having a three-dimensionally arranged metal fiber having a resin core material and a metal coating layer formed on the surface of the core material, and It can be seen that the negative electrode can improve the peel strength. Further, it can be seen that the secondary battery of Example 1 including the positive electrode and the negative electrode has a low impedance 10 minutes after the impregnation with the electrolytic solution. Furthermore, the secondary battery of Example 1 was prepared by dipping the electrolyte solution 2
It can be seen that the remaining amount of DBP becomes 0% after time. This is the permeability of the electrolytic solution by using the current collector,
This is because the DBP removal rate and the adhesion are improved.

On the other hand, it is understood that the positive electrode and the negative electrode using the metal foil as the current collector have extremely low peel strength. Further, it can be seen that the secondary battery of Comparative Example 1 including the positive electrode and the negative electrode has a high impedance and, in addition, the remaining amount of DBP is remarkably large one week after immersion in the electrolytic solution. Further, it can be seen that the positive electrode and the negative electrode using the expanded metal or the punched metal as the current collector are inferior in peel strength to those in Example 1. In addition, the secondary batteries of Comparative Examples 2 and 3 including the positive electrode and the negative electrode,
The remaining amount of DBP is 0 when 2 hours have passed after immersion in the electrolytic solution.
Although it is%, it can be seen that the impedance is higher than that of the first embodiment. Since the conventional current collector has poor adhesion to the electrode layer, when the electrode layer expands by being immersed in an electrolytic solution, the electrode layer peels off and the impedance increases. Furthermore, when a metal foil is used as the current collector as in Comparative Example 1, the impregnation property of the electrolytic solution is also lowered, and the impedance is significantly increased. Example 2 An electrolytic solution-unimpregnated battery having the same configuration as in Example 1 was produced except that an expanded metal made of aluminum having a thickness of 20 μm was used as the positive electrode current collector. Example 3 A battery having the same structure as in Example 1 except that an expanded metal made of copper having a thickness of 30 μm was used as the negative electrode current collector was prepared.

With respect to the obtained batteries of Examples 2 and 3 not impregnated with the electrolytic solution, the impedance of the battery after immersion in the electrolytic solution was measured in the same manner as described above. Was 16Ω, the impedance after 1 week was 17Ω, and in Example 3, the impedance after 10 minutes was 14Ω and the impedance after 1 week was 14Ω. Further, when the residual amount of DBP was measured in the same manner as described above for Examples 2 and 3, the residual amount was 0% in both Examples 2 and 3 2 hours after the immersion in the electrolytic solution. It can be seen that the effect of improving the impedance is higher when the present invention is applied to the positive electrode using the current collector made of aluminum as in Example 3 than when it is applied to the negative electrode.

A similar experiment was conducted on a current collector having a structure in which hollow metal fibers were three-dimensionally arranged.
It was confirmed that a similar effect was obtained. Further, even when the mixing ratio of the electrode components and the active material were changed, the battery characteristics were similarly improved by using the current collector according to the present invention.

In the above-mentioned embodiment, the example applied to the polymer electrolyte secondary battery has been described, but it has a structure in which the electrode group in which the separator is interposed between the positive electrode and the negative electrode and the non-aqueous electrolytic solution are housed in a closed container. The same can be applied to the non-aqueous electrolyte secondary battery.

[0088]

As described in detail above, according to the present invention, an electrode having a high adhesiveness between a paste containing an active material and a current collector is provided, the impregnation property of a non-aqueous electrolyte is excellent, and the impedance is low. A non-aqueous electrolyte secondary battery having improved cycle characteristics can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing a non-aqueous electrolyte secondary battery (for example, a polymer electrolyte secondary battery) according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Positive electrode collector, 2 ... Positive electrode layer, 3 ... Negative electrode collector, 4 ... Negative layer, 5 ... Solid polymer electrolyte layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoko Matsutani 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Inside Toshiba Battery Co., Ltd.

Claims (8)

[Claims] 1. In a non-aqueous electrolyte secondary battery comprising a positive electrode having a structure in which a paste containing an active material is supported on a current collector, a negative electrode, and a non-aqueous electrolyte, the current collector of the positive electrode is hollow. A non-aqueous electrolyte secondary battery having a structure in which metal fibers are three-dimensionally arranged. 2. In a non-aqueous electrolyte secondary battery comprising a positive electrode having a structure in which a paste containing an active material is supported on a current collector, a negative electrode, and a non-aqueous electrolyte, the current collector of the positive electrode is a resin. A non-aqueous electrolyte secondary battery having a structure in which a core material and metal fibers having a metal coating layer formed on the surface of the core material are three-dimensionally arranged. 3. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode having a structure in which a paste containing an active material is carried on a current collector, and a non-aqueous electrolyte secondary battery, wherein the current collector of the negative electrode is hollow. A non-aqueous electrolyte secondary battery having a structure in which metal fibers are three-dimensionally arranged. 4. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode having a structure in which a paste containing an active material is carried on a current collector, and a non-aqueous electrolyte secondary battery, wherein the current collector of the negative electrode is a resin. A non-aqueous electrolyte secondary battery having a structure in which a core material and metal fibers having a metal coating layer formed on the surface of the core material are three-dimensionally arranged. 5. A positive electrode having a structure in which a paste containing an active material is carried on a current collector, a negative electrode having a structure in which a paste containing an active material is carried on a current collector, and a non-aqueous electrolyte-containing non-aqueous electrolyte. In the water electrolyte secondary battery, the current collectors of the positive electrode and the negative electrode have a structure in which hollow metal fibers are three-dimensionally arranged. 6. A positive electrode having a structure in which a paste containing an active material is carried on a current collector, a negative electrode having a structure in which a paste containing an active material is carried on a current collector, and a non-aqueous electrolyte-containing non-aqueous electrolyte. In the water electrolyte secondary battery, the current collectors of the positive electrode and the negative electrode have a structure in which metal fibers having a resin core material and a metal coating layer formed on the surface of the core material are three-dimensionally arranged. A non-aqueous electrolyte secondary battery characterized by the above. 7. A positive electrode having a structure in which a paste containing an active material is carried on a current collector, a negative electrode having a structure in which a paste containing an active material is carried on a current collector, and a non-aqueous electrolyte-containing non-aqueous electrolyte. In the water electrolyte secondary battery, the current collector of the positive electrode has a structure in which hollow metal fibers are three-dimensionally arranged, and the current collector of the negative electrode is a resin core material and the surface of the core material. A non-aqueous electrolyte secondary battery having a structure in which metal fibers having a formed metal coating layer are three-dimensionally arranged. 8. A positive electrode having a structure in which a paste containing an active material is carried on a current collector, a negative electrode having a structure in which a paste containing an active material is carried on a current collector, and a non-aqueous electrolyte provided non-aqueous electrolyte. In the water electrolyte secondary battery, the current collector of the positive electrode has a structure in which metal fibers having a resin core material and a metal coating layer formed on the core material surface are three-dimensionally arranged, and The current collector of the negative electrode has a structure in which hollow metal fibers are three-dimensionally arranged, which is a non-aqueous electrolyte secondary battery.