JP2009301898A - Collector, method for manufacturing the same, electrode, and electrical storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a collector which can decrease an internal resistance when applied to an electrical storage battery, and to provide: a method for manufacturing the collector; and an electrode. <P>SOLUTION: The collector for the electrical storage battery includes: a metal substrate; an adhesive layer formed on the surface of the substrate and having the substrate and an electroconductive material with electroconductivity mixed with each other; and an electroconductive layer formed on the adhesive layer and having the electroconductive material, wherein the particle diameter of the electroconductive material located in the surface side of the electroconductive layer is larger than that of the electroconductive material located in the substrate side of the adhesive layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a current collector that can reduce internal resistance when applied to a power storage device, a manufacturing method thereof, an electrode, and a power storage device.

  In recent years, from the viewpoint of solving environmental problems caused by exhaust gas from an internal combustion engine, development of automobiles with reduced exhaust gas emissions or automobiles that do not emit exhaust gas has been underway. As one of vehicles that reduce exhaust gas emissions, there is a hybrid vehicle that combines an internal combustion engine and an electric motor. Moreover, there is an electric vehicle as one of vehicles that do not emit exhaust gas. These automobiles employ electricity stored in a power storage device such as a secondary battery or a capacitor as a power source.

  The performance required for power storage devices mounted on automobiles is required to be small and lightweight, and to be able to be charged and discharged with a large current instantaneously as needed, that is, to have a high output density. . In order to achieve a high output density, it is necessary to reduce the internal resistance of the power storage device. In order to reduce the internal resistance of the power storage device, it is necessary to reduce the resistance of various members such as electrodes constituting the power storage device.

  As a power storage device mounted on a vehicle, an electrode body is formed by winding or laminating a sheet-like electrode (positive and negative electrodes) with a separator interposed therebetween, and this electrode body is housed in a case together with an electrolytic solution. The one with the form is common.

  Examples of the sheet-like electrode include those having a structure in which an electrode mixture layer containing an electrode active material or the like is formed on the surface of a metal foil as a current collector. In the sheet-like electrode, there is a considerable influence on the internal resistance by the transfer of electricity between the current collector and the electrode mixture layer. Further, if the electrode material is not uniformly distributed on the current collector, the reaction accompanied by the movement of charges becomes non-uniform, leading to an increase in the internal resistance of the battery.

  An aluminum foil may be used for the current collector in the power storage device. For example, it is used for a current collector of a positive electrode of a lithium secondary battery. In general, a passive film made of aluminum oxide is formed on the surface of aluminum. That is, a current collector made of normal aluminum has a passive film having a large electric resistance between the electrode mixture layer.

In forming an electrode mixture layer on a current collector, generally, an electrode active material is mixed with a binder, a conductive material, and a solvent to form a slurry, which is applied to the current collector and dried. Electrodes are formed. At this time, an organic solvent such as N-methyl-2-pyrrolidone is used as the solvent. However, it is desired to use water from the viewpoint of environmental considerations, materials and equipment costs. When water is used as the solvent when slurrying, coating and drying the electrode material on a current collector made of aluminum foil, the components in the slurry and the aluminum foil cause a chemical reaction (generation of Al (OH) _x ) Further, formation of a further film and generation of non-uniform electrodes due to generation of reaction gas occur, and the internal resistance of the battery increases.

  In addition, when the produced power storage device is driven, the current collector made of aluminum is exposed to a high potential, and the aluminum constituting the current collector reacts with the surrounding electrolyte to increase the surface of the current collector. A resistive film is formed.

  As described above, the conventional power storage device has a problem that the internal resistance increases due to the high resistance film formed on the surface of the current collector made of aluminum and the non-uniformity of the electrodes. When the internal resistance increases, a voltage drop at the time of charging / discharging with a large current is caused, and the output is reduced.

  Patent Documents 1 to 3 are disclosed for the problem of passive films such as oxide films and high resistance films.

  Patent Document 1 discloses that electron conductive particles having a particle diameter smaller than the thickness of the aluminum foil are embedded in the surface of the aluminum foil. By embedding the electron conductive particles in the aluminum foil, an increase in internal resistance is suppressed.

  Patent Document 2 discloses that fine carbon having a median diameter of 0.8 μm or less is applied to the surface of a current collector. By attaching the fine carbon, the formation of a passive film at the interface between the current collector and the electrode active material or the electrolytic solution is prevented.

  Patent Document 3 discloses that the outer surface of the current collector is formed of hafnium or a hafnium alloy.

  However, since the current collectors disclosed in Patent Documents 1 to 3 are subjected to further treatment in a state where an oxide film is formed on the surface, the passive film on the surface of the aluminum foil remains, There was a problem that the effect of sufficiently reducing the internal resistance could not be obtained.

Furthermore, in the technologies disclosed in Patent Documents 1 to 3, the aluminum foil and the conductive surface layer formed on the surface thereof are all joined by the anchor effect derived from the unevenness of the aluminum foil surface. There was a problem in durability and reliability.
JP 7-22606 A Japanese Patent Laid-Open No. 2002-298753 JP 2004-63156 A

  This invention is made | formed in view of the said actual condition, and makes it a subject to provide the electrical power collector which can make internal resistance low, when applied to an electrical storage apparatus, its manufacturing method, and an electrode.

  In order to solve the above-mentioned problems, the present inventors have made studies on the structure of the current collector, and as a result, have come to make the present invention.

  That is, the current collector of the present invention is formed on a metal base material, a bonding layer formed on the surface of the base material, and a base material and a conductive material having conductivity, and formed on the bonding layer, and is electrically conductive. A conductive material layer having a conductive material, and a conductive material particle having a particle diameter of the conductive material positioned on the surface side of the conductive layer and the conductive material particles positioned on the base material side of the bonding layer It is characterized by being larger than the diameter.

  In addition, the current collector manufacturing method of the present invention includes a metal base material, a bonding layer formed on the surface of the base material, in which the base material and a conductive material having conductivity are mixed, and formed on the bonding layer. A method of manufacturing a current collector for a power storage device having a conductive layer, a step of forming a bonding layer on a surface of a substrate, and a bonding layer base on the surface of the bonding layer. Spraying a conductive material having a particle size larger than that of the conductive material located on the material side together with a carrier gas.

  Moreover, the electrode of this invention is on the surface of the electrical power collector manufactured by the electrical power collector in any one of Claims 1-16, or the manufacturing method of Claims 17-31, and an electrical power collector. And an electrode active material layer formed.

  Moreover, the electrical storage apparatus of this invention uses the electrical power collector manufactured by the electrical power collector in any one of Claims 1-16, or the manufacturing method of Claims 17-31, It is characterized by the above-mentioned. And

  Since the current collector of the present invention has a surface formed by a conductor layer having a conductive material having conductivity, the surface of the base material itself is formed when an electrode of a power storage device using an organic electrolyte is formed. However, it is no longer exposed to the slurry and electrolyte used in electrode preparation. As a result, a passive film having a high resistance is not formed on the surface of the substrate, and an increase in internal resistance is suppressed and output characteristics are improved.

  In the current collector of the present invention, a conductor layer is formed on the surface of the substrate. This conductor layer uses a conductive material having a large particle diameter, and has a small gap between the conductive material particles, and can be formed by controlling the thickness according to the particle diameter. This suppresses the formation of a film by reaction with water contained in the slurry used during electrode preparation, non-uniformity of the electrode due to gas generation, and the formation of a film formed during an electrochemical reaction via the electrolyte. Can do.

  Thus, the current collector of the present invention is a current collector that does not increase in internal resistance when electrodes are formed.

  The method for producing a current collector of the present invention can produce a current collector whose surface is covered with a conductor layer while avoiding damage to the substrate as much as possible. Furthermore, the conductor layer can be formed with less gaps and with the thickness controlled by the particle diameter. As a result, the electrical resistance of the current collector can be reduced and the electrode material can be made uniform, so that the internal resistance can be reduced and the output can be improved.

  The electrode of the present invention uses a current collector that does not increase internal resistance, and suppresses an increase in internal resistance of the current collector. Furthermore, in the electrode of the present invention, since the conductive material forms a conductor layer with the surface having irregularities, the adhesion with the electrode active material is improved, the output is improved, and the durability characteristics are improved.

  The power storage device of the present invention uses a current collector that does not increase internal resistance, and suppresses an increase in internal resistance of the current collector.

(Current collector)
The current collector for the power storage device of the present invention is formed on a metal base material, a bonding layer formed on the surface of the base material, and a base material and a conductive material having conductivity, and the bonding layer. And a conductor layer having a conductive material. In the current collector for the power storage device of the present invention, the particle diameter of the conductive material located on the surface side of the conductor layer is larger than the particle diameter of the conductive material located on the substrate side of the bonding layer. . Here, each of the particles of the conductive material located on the surface side of the conductor layer and the particles of the conductive material located on the substrate side of the bonding layer change in shape when the particles of the conductive material are arranged in each layer. In the case, the particle diameter of the conductive material before the change occurs is shown.

  The current collector of the present invention has a bonding layer in which conductive material particles having a small particle diameter are mixed in the base material on the surface of the base material. Since the conductive material particles contained in the bonding layer have a small particle diameter, the gap between the conductive material particles is small. That is, the base material is not exposed by arranging the conductive material particles densely. This suppresses the formation of a film due to reaction with water contained in the slurry during electrode material formation, electrode non-uniformity due to gas generation, and the formation of a film formed during an electrochemical reaction via an electrolytic solution. Can do.

  The current collector of the present invention has conductive material particles having a large particle diameter on the surface side of the conductor layer. By having a conductive material having a large particle diameter, the conductor layer can be formed by controlling the thickness by the particle diameter. Furthermore, when conductive material particles having a large particle diameter are used, large gaps are formed between the particles. However, in the present invention, a bonding layer having a conductive material having a small particle diameter is formed on the surface of the substrate. The material is covered with a conductive material, and the film formed by reaction with water etc. contained in the slurry at the time of electrode material formation, non-uniformity of the electrode due to gas generation, the film formed at the time of the electrochemical reaction via the electrolytic solution Formation can be suppressed.

  Further, when the current collector of the present invention is formed by spraying conductive material particles to form a conductor layer, the conductor particles having a large particle diameter have a large kinetic energy, and are higher when they collide with the base material. Stress is applied and the conductive particles are buried to a deeper position. Therefore, the conductive material particles are bonded to each other with a strong bonding force, and more conductive particles can be bonded.

  The current collector of the present invention has a surface formed of a conductor layer having a conductive material having conductivity. By having a conductor layer, when the electrode of a power storage device using an organic electrolyte is formed, the substrate is not exposed to the electrolyte, and a passive film (high resistance film) is formed on the surface of the substrate. Disappear. An increase in internal resistance due to the passive film is suppressed, and a decrease in output characteristics of the power storage device due to an increase in internal resistance is suppressed.

  In the current collector of the present invention, the base material and the conductor layer are joined by the joining layer. The bonding layer is a mixture of aluminum constituting the substrate and a conductive material that exhibits conductivity in the conductor layer, and the bonding layer and the substrate and the bonding of the substrate bonding layer and the conductor layer are the same type of material. It becomes possible to perform it mutually, and it joins firmly. Accordingly, even when the current collector is used in the power storage device, the conductor layer does not peel off, and the current collector has excellent durability and reliability.

  It is preferable that the bonding layer and the conductor layer become larger as the particle diameter of the conductive material contained increases from the substrate side to the surface side. As the particle diameter of the conductive material increases from the substrate side to the surface side, the gap between the conductive material particles is small, and the thickness of the layer can be controlled by the particle diameter.

  The conductor layer is preferably formed by spraying a conductive material on the base material on which the bonding layer is formed. The bonding layer is preferably formed by spraying a conductive material on the surface of the substrate. Since the bonding layer and the conductor layer are formed by spraying a conductive material, the conductive material hits the base material (bonding layer, conductor layer) with energy. As a result, a bonding layer or a conductor layer having a conductive material can be formed.

  Further, when a conductive material having a small particle diameter is sprayed on the base material, the conductive material particles break through the passive film formed on the surface of the base material and enter and diffuse into the base material. Thereby, the joining layer in which the base material and the conductive material are mixed is formed. By using small particles, the bonding layer is formed with very few microscopic gaps. When a conductive material having a large particle diameter is sprayed on the surface of the bonding layer, the conductive material is bonded directly to the base material via the bonding layer bonded to the current collector or the bonding layer. Thereby, there are few clearance gaps and the thickness of a junction part and a conductive material particle part can be made to increase.

  The bonding layer is preferably formed by diffusing a conductive material from the surface of the base material to the inside. When the conductive material diffuses from the surface of the base material to the inside, the vicinity of the surface of the bonding layer contains a large amount of the conductive material, and the proportion of the conductive material contained gradually decreases from the surface to the inside. By becoming such a structure, a base material and a conductor layer can be joined firmly. That is, in the bonding layer, the concentration of the conductive material is preferably increased from the substrate side toward the conductor layer side. Further, by diffusing the conductive material into the base material, there is no interface between the base material and the bonding layer, and the conductivity of the current collector is improved. The conductive material is preferably diffused at a molecular level in a metal matrix constituting the substrate.

  Moreover, by diffusing the conductive material in the base material to form a bonding layer, the oxide film present on the surface of the metal constituting the base material is removed when the conductive material is diffused, and the internal resistance is increased by the oxide film. Is suppressed.

In the current collector of the present invention, the kinetic energy (1/2 m _{x + 1} V _{x + 1} ² ) when the conductive material is sprayed on the surface of the layer formed by spraying the conductive material forms the front layer of the bonding layer and the conductive layer. It is preferable that it is larger than the kinetic energy (1/2 m _x V _x ² ) at the time of spraying. By increasing the kinetic energy of the conductive material particles sprayed later, higher stress is applied when the conductive material particles collide with the front layer or the base material, and the particles are buried to a deeper position. Therefore, the bonding force with the base material and the front layer becomes strong, and more particles can be bonded than when particles having a small particle diameter are continuously ejected. Thereby, a thicker layer can be formed. Further, the number of particles that can be joined increases, so that the material utilization efficiency can be greatly improved, and the material cost can be reduced.

  In the current collector of the present invention, the ratio of the average particle diameter of the conductive material sprayed to the average particle diameter of the conductive material sprayed to form the previous layer is preferably 1.2 / 1 or more. . When the ratio of the average particle diameter of the conductive material is within this range, a dense layer can be formed from a conductive material having a small particle diameter, and a thicker layer can be formed from a conductive material having a large particle diameter.

  In the current collector of the present invention, it is preferable that the spraying speed of the conductive material sprayed is faster than the spraying speed of the conductive material sprayed to form the previous layer. By controlling the spraying speed of the conductive material, it is possible to increase the kinetic energy when spraying a conductive material with a large particle size, to form a dense layer from a conductive material with a small particle size, and to conduct with a large particle size. Thicker layers can be formed from the material. It is more preferable that the ratio of the spraying speed of the conductive material sprayed to the spraying speed of the conductive material sprayed to form the previous layer is 1.33 / 1 or more. In the current collector of the present invention, the conductive material is preferably sprayed at 150 to 450 m / sec.

  In the current collector of the present invention, it is preferable that 90% or more of the surface of the base material is covered with a conductive material. 90% or more of the surface of the base material is covered with the conductive material (bonding layer and conductor layer), so that the base material is covered with the conductive material, and by reaction with water contained in the slurry at the time of forming the electrode material It is possible to suppress film formation, electrode non-uniformity due to gas generation, and formation of a film formed during an electrochemical reaction via an electrolytic solution.

In the current collector of the present invention, the material of the conductive material is not particularly limited, and can be appropriately selected depending on the electrolytic solution, use conditions, and the like when used in the power storage device. The passive film produced on the surface of the substrate varies depending on the electrolytic solution of the power storage device in which the current collector is used, the use conditions, and the like. For example, an electrolytic solution containing LiPF ₆ as an electrolyte is used for a lithium ion battery, and a passive film formed at about 4 V in a current collector made of aluminum as a base material of the lithium ion battery is aluminum fluoride. It is. As described above, the material and thickness of the passive film generated vary depending on the type and potential of the electrolytic solution to which the current collector is exposed in the power storage device. For this reason, the material of the conductive material can be appropriately selected depending on the type and potential of the electrolytic solution to which the current collector is exposed in the power storage device. For example, at least one of carbon materials, conductive ceramics, conductive oxides, and metal materials can be given. These may be used in combination.

  The carbon material is preferably at least one of graphite, carbon black, acetylene black, and carbon nanotube. The conductive ceramic is preferably at least one of titanium carbide and titanium nitride. The conductive oxide is preferably at least one of vanadium oxide, titanium oxide, niobium oxide, cobalt oxide, manganese oxide, nickel oxide, silver oxide, zinc oxide, and tungsten oxide. The metal material is preferably at least one of nickel, silver, gold, and platinum.

  By selecting a carbon material, a conductive ceramic, a conductive oxide, or a metal material from these materials, the conductor layer can have electrical conductivity without increasing the internal resistance.

  In the current collector of the present invention, the metal constituting the substrate is not particularly limited. The current collector of the present invention is more preferably aluminum because it exhibits an effect particularly when the substrate is aluminum. Here, the aluminum may be not only pure aluminum but also an aluminum alloy. For example, an aluminum alloy containing manganese has improved strength and can reduce the thickness of the base material. Moreover, it is preferable that the base material is not subjected to heat treatment such as annealing.

  The substrate is preferably formed with a thickness of 30 μm or less. When the thickness of the substrate exceeds 30 μm, the thickness of the current collector becomes too thick. When the thickness of the current collector is increased, the ratio of the base material used as the electrode when the power storage device is formed increases, the amount of active material per volume decreases, and volume efficiency decreases.

  The bonding layer is preferably formed with a thickness of 0.01 μm or more. Here, the thickness of the bonding layer indicates the thickness of the portion including the conductive material. By forming the bonding layer with a thickness of 0.01 μm or more, the effect of bonding the base material and the conductor layer is exhibited.

(Production method)
The method for producing a current collector of the present invention is formed on a metal base material, a joining layer formed on the surface of the base material, and a base material and a conductive material having conductivity, and formed on the joining layer, A method of manufacturing a current collector for a power storage device having a conductive layer having a conductive material, the step of forming a bonding layer on the surface of the substrate, and the substrate side of the bonding layer on the surface of the bonding layer And spraying a conductive material having a particle size larger than that of the conductive material positioned together with the carrier gas.

  In the method for producing a current collector of the present invention, a metal base material, a bonding layer formed on the surface of the base material, in which the base material and a conductive material having conductivity are mixed, and formed on the bonding layer, A method of manufacturing a current collector for a power storage device having a conductive layer having a conductive material. That is, the manufacturing method of the current collector of the present invention is a manufacturing method capable of manufacturing the current collector.

  In the method for producing a current collector of the present invention, first, a bonding layer is formed on the surface of the base material, and then on the surface of the bonding layer, the particle diameter of the conductive material located on the base material side of the bonding layer is larger. A conductive material having a particle size is sprayed together with a carrier gas. Thereby, said electrical power collector can be manufactured.

  The bonding layer is preferably formed by spraying a conductive material on the surface of the substrate. That is, by spraying particles of a conductive material, the conductive material hits the base material with energy, and a bonding layer or a conductor layer having the conductive material can be formed.

  When a conductive material having a small particle diameter is sprayed on the base material, the conductive material particles break through the passive film formed on the surface of the base material and enter and diffuse into the base material. Thereby, the joining layer in which the base material and the conductive material are mixed is formed. By using small particles, the bonding layer is formed with very few microscopic gaps. When a conductive material having a large particle diameter is sprayed on the surface of the bonding layer, the conductive material is bonded directly to the base material via the bonding layer bonded to the current collector or the bonding layer. Thereby, there are few clearance gaps and the thickness of a junction part and a conductive material particle part can be made to increase.

  In the bonding layer formed by spraying the conductive material particles on the base material, the conductive material is formed by diffusing from the surface of the base material to the inside. When the conductive material diffuses from the surface of the base material to the inside, the vicinity of the surface of the bonding layer contains a large amount of the conductive material, and the proportion of the conductive material contained gradually decreases from the surface to the inside. By becoming such a structure, a base material and a conductor layer can be joined firmly. Further, by diffusing the conductive material into the base material, there is no interface between the base material and the bonding layer, and the conductivity of the current collector is improved. The conductive material is preferably diffused at a molecular level in a metal matrix constituting the substrate.

  Moreover, by diffusing the conductive material in the base material to form a bonding layer, the oxide film present on the surface of the metal constituting the base material is removed when the conductive material is diffused, and the internal resistance is increased by the oxide film. Is suppressed.

In the method for producing a current collector of the present invention, the bonding layer and the conductor layer have a kinetic energy (1/2 m _{x + 1} V _{x + 1} ² ) when the conductive material is sprayed on the surface of the layer to which the conductive material is sprayed. It is preferable that it is larger than the kinetic energy (1/2 m _x V _x ² ) at the time of spraying to form a layer. By increasing the kinetic energy of the conductive material particles sprayed later, higher stress is applied when the conductive material particles collide with the front layer or the base material, and the particles are buried to a deeper position. Therefore, the bonding force with the base material and the front layer becomes strong, and more particles can be bonded than when particles having a small particle diameter are continuously ejected. Thereby, a thicker layer can be formed. Further, the number of particles that can be joined increases, so that the material utilization efficiency can be greatly improved, and the material cost can be reduced.

  In the current collector manufacturing method of the present invention, the ratio of the average particle diameter of the conductive material sprayed to the average particle diameter of the conductive material sprayed to form the previous layer is 1.2 / 1 or more. It is preferable. When the ratio of the average particle diameter of the conductive material is within this range, a dense layer can be formed from a conductive material having a small particle diameter, and a thicker layer can be formed from a conductive material having a large particle diameter.

  In the method for producing a current collector of the present invention, it is preferable that the spraying speed of the conductive material sprayed is faster than the spraying speed of the conductive material sprayed to form the previous layer. By controlling the spraying speed of the conductive material, it is possible to increase the kinetic energy when spraying a conductive material with a large particle size, to form a dense layer from a conductive material with a small particle size, and to conduct with a large particle size. Thicker layers can be formed from the material. It is more preferable that the ratio of the spraying speed of the conductive material sprayed to the spraying speed of the conductive material sprayed to form the previous layer is 1.33 / 1 or more. In the current collector of the present invention, the conductive material is preferably sprayed at 150 to 450 m / sec.

  In the method for producing a current collector of the present invention, it is preferable that 90% or more of the surface of the base material is covered with a conductive material. 90% or more of the surface of the base material is covered with the conductive material (bonding layer and conductor layer), so that the base material is covered with the conductive material, and by reaction with water contained in the slurry at the time of forming the electrode material It is possible to suppress film formation, electrode non-uniformity due to gas generation, and formation of a film formed during an electrochemical reaction via an electrolytic solution.

In the method for manufacturing a current collector of the present invention, the material of the conductive material is not particularly limited, and can be appropriately selected depending on the electrolytic solution used in the power storage device, the use conditions, and the like. The passive film produced on the surface of the substrate varies depending on the electrolytic solution of the power storage device in which the current collector is used, the use conditions, and the like. For example, an electrolytic solution containing LiPF ₆ as an electrolyte is used for a lithium ion battery, and a passive film formed at about 4 V in a current collector made of aluminum as a base material of the lithium ion battery is aluminum fluoride. It is. As described above, the material and thickness of the passive film generated vary depending on the type and potential of the electrolytic solution to which the current collector is exposed in the power storage device. For this reason, the material of the conductive material can be appropriately selected depending on the type and potential of the electrolytic solution to which the current collector is exposed in the power storage device. For example, at least one of carbon materials, conductive ceramics, conductive oxides, and metal materials can be given. These may be used in combination.

  The carbon material is preferably at least one of graphite, carbon black, acetylene black, and carbon nanotube. The conductive ceramic is preferably at least one of titanium carbide and titanium nitride. The conductive oxide is preferably at least one of vanadium oxide, titanium oxide, niobium oxide, cobalt oxide, manganese oxide, nickel oxide, silver oxide, zinc oxide, and tungsten oxide. The metal material is preferably at least one of nickel, silver, gold, and platinum.

  By selecting a carbon material, a conductive ceramic, a conductive oxide, or a metal material from these materials, the conductor layer can have electrical conductivity without increasing the internal resistance.

  In the method for producing a current collector of the present invention, the metal constituting the substrate is not particularly limited. The current collector of the present invention is more preferably aluminum because it exhibits an effect particularly when the substrate is aluminum. Here, the aluminum may be not only pure aluminum but also an aluminum alloy. For example, an aluminum alloy containing manganese has improved strength and can reduce the thickness of the base material. Moreover, it is preferable that the base material is not subjected to heat treatment such as annealing.

  The carrier gas is not particularly limited, but it is desirable to employ a gas that is inert or low in activity under an injection atmosphere such as nitrogen gas, air, or argon. As the pressure of the carrier gas, it is desirable to employ a pressure at which the fine particle material has the above-mentioned preferable speed. For example, 0.1 MPa to 1.0 MPa is desirable to realize the fine particle injection speed described above. .

  The substrate is preferably formed with a thickness of 30 μm or less. When the thickness of the substrate exceeds 30 μm, the thickness of the current collector becomes too thick. When the thickness of the current collector is increased, the ratio of the base material used as the electrode when the power storage device is formed increases, the amount of active material per volume decreases, and volume efficiency decreases.

  The bonding layer is preferably formed with a thickness of 0.01 μm or more. Here, the thickness of the bonding layer indicates the thickness of the portion including the conductive material. By forming the bonding layer with a thickness of 0.01 μm or more, the effect of bonding the base material and the conductor layer is exhibited.

(electrode)
The electrode of the present invention is formed on the surface of the current collector, the current collector manufactured by the current collector according to any of claims 1 to 16, or the manufacturing method according to claims 17 to 31. An electrode active material layer. That is, the electrode of the present invention is an electrode using the above-described current collector, and the above-mentioned current collector has a conductor layer formed on the surface of a substrate via a bonding layer, and has an internal resistance. This is an electrode that suppresses the rise in the resistance and exhibits high durability and reliability.

  The electrode of the present invention is an electrode using the above-described current collector, and is an electrode having an electrode active material layer on a conductor layer. The electrode active material layer has an electrode active material that can occlude and release ions, can exchange electrons associated with a redox reaction, or can store charges reversibly. An electrode active material is a substance that causes an electrode reaction when the electrode of the present invention is used as an electrode of a power storage device. The electrode reaction in which the electrode active material is generated is not limited. The reaction of occluding and releasing ions into the crystal structure like the electrode reaction of a lithium battery, or the electron accompanying the redox reaction like a radical battery. A reaction for giving and receiving, a reaction for forming an electric double layer on the surface thereof, such as an electric double layer capacitor, can be mentioned.

  The electrode of the present invention may be used for either the positive electrode or the negative electrode. For example, when used as an electrode of a lithium ion battery, a positive electrode is preferable.

  In the electrode of the present invention, the electrode active material includes an electrode reaction that occludes / releases ions, an electrode reaction that exchanges electrons associated with an oxidation-reduction reaction, and an electrode reaction that reversibly carries ions when an electricity storage device is configured. The substance is not particularly limited as long as it is a substance that causes at least one kind of electrode reaction. The electrode active material is preferably at least one of a metal oxide compound and a radical stabilizing compound.

The metal oxide compound may be any metal oxide compound that can occlude and release lithium ions. When the metal oxide compound is composed of a compound capable of inserting and extracting lithium ions, a lithium ion battery can be formed using the electrode of the present invention. Examples of the metal oxide compound include compounds containing cobalt oxide, nickel oxide, manganese oxide, iron olivic acid oxide in a metal oxide compound capable of occluding and releasing lithium ions. The composite oxide can be mentioned. That is, the metal oxide compound is a metal oxide compound capable of occluding and releasing lithium ions, at least one of a cobalt oxide, a nickel oxide, a manganese oxide, and an iron olivic acid oxide, or a combination thereof. A compound containing a complex is preferable. More _{specifically,} and _{LiCoO 2, LiNiO 2, LiMnO 2} , LiMn 2 O 4, LiNi 1-x-y Co x M y O 2 (M is Al, Sr, Mg, a metal element such as La) of such One or more kinds of lithium transition metal oxides or a composite thereof can be used.

  The radical compound has unpaired electrons, and these unpaired electrons are used for the electrode reaction. That is, the unpaired electrons are taken out as current through the current collector. As a result, an electrode reaction for transferring electrons accompanying the redox reaction proceeds. The power storage device using this electrode reaction exhibits the effect of obtaining high output from the ease of electron transfer. The radical compound is not particularly limited as long as it is a compound having an unpaired electron contributing to the electrode reaction. The radical compound is preferably at least one of a compound having a nitroxyl radical, a compound having an oxy radical, and a compound having a nitrogen radical.

  Examples of electrode reactions that can store charges reversibly include reactions that occur at the electrodes of capacitors. Examples of the active material capable of reversibly storing charges include active materials used in conventionally known capacitors, and examples thereof include carbonaceous materials such as activated carbon.

  In the electrode of the present invention, the bonding layer is preferably formed with a thickness of 0.01 μm or more. Here, the thickness of the bonding layer indicates the thickness of the portion including the conductive material. By forming the bonding layer with a thickness of 0.01 μm or more, the effect of bonding the base material and the conductor layer is exhibited.

  The substrate is preferably formed with a thickness of 30 μm or less. When the thickness of the substrate exceeds 30 μm, the thickness of the current collector becomes too thick. When the thickness of the current collector is increased, the ratio of the base material used as the electrode when the power storage device is formed increases, the amount of active material per volume decreases, and volume efficiency decreases.

In the electrode of the present invention, the material of the conductive material is not particularly limited, and can be appropriately selected depending on the electrolytic solution when used in the power storage device, use conditions, and the like. The passive film produced on the aluminum surface differs depending on the electrolytic solution and the use conditions of the power storage device in which the current collector is used. For example, an electrolytic solution containing LiPF ₆ as an electrolyte is used for a lithium ion battery, and the passive film formed at about 4 V in the current collector of this lithium ion battery is aluminum fluoride. As described above, the material and thickness of the passive film generated vary depending on the type and potential of the electrolytic solution to which the current collector is exposed in the power storage device. For this reason, the material of the conductive material can be appropriately selected depending on the type and potential of the electrolytic solution to which the current collector is exposed in the power storage device. For example, at least one of carbon materials, conductive ceramics, conductive oxides, and metal materials can be given. These may be used in combination.

  The carbon material is preferably at least one of graphite, carbon black, acetylene black, and carbon nanotube. The conductive ceramic is preferably at least one of titanium carbide and titanium nitride. The conductive oxide is preferably at least one of vanadium oxide, titanium oxide, niobium oxide, cobalt oxide, manganese oxide, nickel oxide, silver oxide, zinc oxide, and tungsten oxide. The metal material is preferably at least one of nickel, silver, gold, and platinum.

  By selecting a carbon material, a conductive ceramic, a conductive oxide, or a metal material from these materials, the conductor layer can have electrical conductivity without increasing the internal resistance.

  In the electrode of the present invention, the aluminum constituting the substrate may be not only pure aluminum but also an aluminum alloy. For example, an aluminum alloy containing manganese has improved strength and can reduce the thickness of the base material. Moreover, it is preferable that the base material is not subjected to heat treatment such as annealing.

  If the electrode of this invention is a method which can form an active material layer in the conductor layer of a collector, the manufacturing method will not be limited. For example, a method of producing a current collector having a base material, a bonding layer and a conductor layer, applying a paste containing an electrode active material on the conductor layer, and drying to form an active material layer can be mentioned. it can. The active material layer may be pressed and compressed after applying and drying a paste containing an electrode active material on the conductor layer.

(Power storage device)
The power storage device of the present invention uses the current collector according to any one of claims 1 to 16 or the current collector manufactured by the manufacturing method according to claims 17 to 31. That is, a power storage device using the electrode according to claims 32 to 37.

  The power storage device of the present invention can have a configuration similar to that of a conventionally known power storage device except for the above-described current collector and electrode. That is, the power storage device can be configured such that an electrode body is formed using an electrode manufactured using the current collector, and the electrode body is sealed in a container together with a non-aqueous electrolyte.

  The power storage device of the present invention is preferably a secondary battery. The type of the secondary battery is not particularly limited as long as it can be repeatedly charged and discharged, and a conventionally known secondary battery can be used. For example, a secondary battery using an organic electrolyte as an electrolyte such as a lithium battery can be given. Since the energy density is high, the secondary battery is more preferably a non-aqueous secondary battery. Examples of the non-aqueous secondary battery include a lithium ion battery. In the lithium ion battery, it is preferable to use the current collector as a positive electrode current collector.

  The power storage device of the present invention is preferably a capacitor. The type of the capacitor is not particularly limited as long as it can be repeatedly charged and discharged, and a conventionally known capacitor can be used. The capacitor is preferably an electric double layer type capacitor excellent in high-speed response during charge / discharge.

  Further, the secondary battery and the capacitor may be either a single battery having one electrode body or an assembled battery including a plurality of single batteries. Further, it may be a single cell battery in which one electrode body is housed in a case, or may be a multiple cell battery in which a plurality of electrode bodies are housed in one.

  Hereinafter, the present invention will be described using examples.

As an example of the present invention, an aluminum current collector and a positive electrode were manufactured.
(Preparation of current collector)
Titanium carbide particles were used as the conductive material. The titanium carbide particles were classified into particles having a 50% average particle radius (D50) of 0.83, 0.91, 1.0, 1.58, 2.00, and 3.50 μm.

  As the base material, an aluminum foil made of an H material having a thickness of 15 μm (manufactured by Nippon Foil Co., Ltd., JIS stipulated 1N30 material) was used. This aluminum foil is an aluminum foil that has not been heat-treated.

  This aluminum foil was fixed to the surface of the porous ceramic material. And vacuum suction was carried out from the back surface side of the ceramic material, and aluminum foil was stuck to the ceramic material.

  Titanium carbide particles were sprayed onto the surface of the aluminum foil adhered to the surface of the ceramic material using a carrier gas under normal temperature conditions. The spraying of the titanium carbide particles was performed by spraying the particles onto the targeted portion of the aluminum foil by moving the nozzle part with a width of 10 mm as a use nozzle. In this test, the nozzle scanning speed was sprayed at an area of 30 × 70 mm at 3 m / min. The same result can be obtained by scanning an aluminum foil (ceramic material) instead of scanning the nozzle.

  Nitrogen gas was used as a carrier gas for spraying titanium carbide particles. The carrier gas pressure was adjusted to 0.1 to 0.5 MPa, and the spraying speed of each particle was measured. As for the spraying conditions, each fine particle material was sprayed in a state where the nozzle used was 10 mm wide, the tip was flat, and a straight tube was adopted, and the aluminum foil was arranged so that the distance from the tip was 1 mm. Here, the injection speed when the particles were sprayed was measured. The ejection speed was measured by photographing with a synchronized high-resolution camera while irradiating the fine particle material ejected from the nozzle with a pulse laser at intervals of 100 ns. As the jetting speed, an average value of the speeds of the measured fine particle materials having the jetting speed in the top 10% was adopted.

  In this example, by controlling the carrier gas pressure in the range of 0.1 MPa to 1.0 MPa, the jetting speed of the titanium carbide particles could be controlled from 150 m / s to 450 m / s.

  In the present embodiment, first, the first titanium carbide particles (first particles) are put into a supply hopper portion and sprayed with a carrier gas under various conditions, and the first particles are sprayed onto the aluminum foil to form a base material made of the aluminum foil. Diffused. Subsequently, the titanium carbide particles in the supply hopper are replaced with second titanium carbide particles (second particles), and the second particles are applied to the base material on which the first particles are diffused to form the bonding layer. Similarly, the conductive layer was formed by spraying with a carrier gas.

  Thereby, the electrical power collector of an Example and a comparative example was able to be manufactured.

  Table 1 shows the particle diameters of the titanium carbide particles (first and second particles) used in the manufactured current collector. Table 1 also shows the kinetic energy ratio at the time of spraying the titanium carbide particles.

The manufactured current collector is formed on a bonding layer formed of a base material made of aluminum foil, a bonding layer formed on the surface of the base material, and a mixed material of the base material and conductive titanium carbide having conductivity. And a conductor layer having a conductive material made of titanium carbide. In the current collector of this example, the particle diameter of the second particles located on the surface side of the conductor layer is larger than the particle diameter of the first particles located on the base material side of the bonding layer.
(Manufacture of positive electrode)
First, lithium nickelate (LiNiO ₂ ) as a positive electrode active material, polytetrafluoroethylene (PTFE) and carboxymethylcellulose (CMC) as binders, carbon black as a conductive additive, and a predetermined amount of each are weighed, and the dispersion medium A positive electrode mixture paste was prepared by dispersing in water.

The prepared positive electrode mixture paste was applied to the surfaces of the current collectors of Examples and Comparative Examples and dried. And it pressed with the hand press and densified the electrode active material on the surface of a current collecting plate. Thereby, the positive electrode in which the positive electrode active material layer was formed on the surface of the current collector was manufactured.
(Manufacture of negative electrode)
Predetermined amounts of graphite as a negative electrode active material and styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) as a binder were weighed and dispersed in water as a dispersion medium to prepare a negative electrode mixture paste.

The prepared negative electrode mixture paste was applied to the surface of a current collector made of copper foil and dried. Thereby, the negative electrode by which the negative electrode active material layer was formed on the surface of copper foil was manufactured.
(Test battery)
The positive electrode and the negative electrode were laminated via a separator made of a polyethylene porous membrane, inserted into a battery case made of aluminum together with an electrolytic solution, and the case was sealed to produce a test battery. The electrolyte solution was such that LiPF ₆ was mixed at a ratio of 1 mol / L in a mixed solvent in which ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 1: 1: 1. To be manufactured.

(Evaluation)
The current collectors, positive electrodes, and batteries of Examples and Comparative Examples were evaluated.

(Evaluation of current collector)
Current collectors of Examples and Comparative Examples Evaluation contents and evaluation methods for the conductor layers obtained as described above will be described below.

  First, the weight efficiency of the particles attached to the current collector was measured.

  This weight efficiency is based on the weight of the aluminum foil before and after the titanium carbide particles are sprayed and the weight of the titanium carbide particles sprayed from the nozzle [(weight of current collector after bonding−weight of Al foil) / sprayed. This was done by comparing the values obtained with [total weight of titanium carbide particles] × 100. Comparison of the calculated values was obtained as a ratio when the value of Comparative Example 1 was 1.0. The weight efficiency values are shown in Table 2.

  Subsequently, the coverage of the particles attached to the current collector was measured.

Coverage is measured by taking a SEM photograph of the current collector, observing the reflected electron image using the SEM photograph, and measuring the coverage of the substrate covered with the conductive material particles from the difference in contrast between the substrate and the conductive material particles. did. The measurement results are shown in Table 2.
(Battery evaluation)
Subsequently, the output of the manufactured battery was evaluated.

  This output was evaluated by measuring the output after charging the battery voltage to SOC 60% (3.72V) after 5 cycles of SOC0 (3V) to 100% (4.1V) charging and discharging. The output is measured by discharging at a current of 1 C for 10 seconds, and by charging at a current of 1 C for 10 seconds, and charging is stopped for 5 minutes, and the difference ΔV (1 C) between the initial voltage and the voltage after 10 seconds is obtained. Similarly, ΔV (xC) is obtained by changing the current value to 2C, 4C, 8C, 12C, 16C, and 20C. Then, from the graph in which the horizontal axis represents the current value and the vertical axis represents ΔV, the current value I at which ΔV, which is the voltage when discharged from SOC 60% to SOC 0%, is 0.72 V is obtained. Then, 3 × I / positive electrode active material weight was calculated as an output value. The measurement results are shown in Table 2. In addition, in the table | surface, it showed by ratio when the measured value of the comparative example 1 was set to 1.0.

  Subsequently, the electrical resistance of the manufactured battery was evaluated.

  The electrode for which the battery output evaluation was completed was cut into a disk shape of φ15 mm and sandwiched between two copper materials. At this time, the positive electrode is compressed between two copper materials with a pressure of 1 MPa, and the positive electrode is pressure-bonded to each of the two copper materials. A voltage was measured by applying a constant current between the two copper materials. The measurement results are shown in Table 2.

  In Examples 1 to 4 in which the second particles are larger than the first particles, the material weight efficiency, the coverage, and the output characteristics are improved as compared with Comparative Example 1 in which only the larger particles are used. It can be confirmed that the electric resistance is reduced.

  In Example 2, the particle size of each of the first and second particles is larger than that in Example 1, and higher stress is applied when the particle collides with the base material. Thereby, the particles are buried to a deeper position. As a result, the bonding force of the base material and the bonding layer with the first particles becomes stronger, and more second particles can be bonded than when the first particles continue to be sprayed. A thick bonding layer could be formed.

  Furthermore, in Example 3, the spraying speed for spraying the second particles is faster than the spraying speed for the first particles. That is, the ratio of the kinetic energy between the second particles and the first particles is increased. Thereby, when a 2nd particle collides with a base material, a higher stress is added. Thereby, the particles are buried to a deeper position. As a result, the bonding force of the base material and the bonding layer with the first particles becomes stronger, and more second particles can be bonded than when the first particles continue to be sprayed. A thick bonding layer could be formed. Furthermore, it turned out that material weight efficiency can be improved.

  In Example 4, the particle size of each of the first and second particles is larger than that in Example 2, and higher stress is applied when the particle collides with the substrate. Thereby, the particles are buried to a deeper position. As a result, the bonding force of the base material and the bonding layer with the first particles becomes stronger, and more second particles can be bonded than when the first particles continue to be sprayed. A thick bonding layer could be formed.

  In Comparative Example 1, the particle diameters of the first and second particles are the same. Even after the first particles (second particles) are further sprayed after the first particles are sprayed to form the bonding layer, the particles are not separated. Bonding and adhesion were not possible, and a conductor layer could not be formed.

  In Comparative Example 2, each evaluation result was almost the same as that of Comparative Example 1, and sufficient effects were not obtained. That is, if the particle diameters of the first and second particles are the same, it can be confirmed that sufficient effects cannot be obtained even if the spraying speed for spraying the second particles is faster than the spraying speed for the first particles. It was.

  Furthermore, Comparative Example 3 is the same as Comparative Example 1 except that the particle size of each of the first and second particles is increased, and each evaluation result is substantially the same as Comparative Example 1. A sufficient effect was not obtained.

  As described above, by using particles having a small particle diameter as the first particles and using particles having a particle diameter larger than the first particles as the second particles, the use efficiency of the material is increased, the coverage is improved, and the output characteristics. It has been found that the electrical resistance can be improved and the electrical resistance can be reduced.

Claims (38)

A metal substrate;
A bonding layer formed on the surface of the base material, in which the base material and a conductive material having conductivity are mixed;
A conductor layer formed on the bonding layer and having the conductive material;
A current collector for a power storage device having
A current collector, wherein a particle diameter of the conductive material located on the surface side of the conductor layer is larger than a particle diameter of the conductive material located on the base material side of the bonding layer.   The current collector according to claim 1, wherein the bonding layer and the conductor layer increase in size as the particle diameter of the conductive material contained increases from the substrate side to the surface side.   The current collector according to claim 1, wherein the conductor layer is formed by spraying the conductive material onto the base material on which the bonding layer is formed.   The current collector according to claim 1, wherein the bonding layer is formed by spraying the conductive material on a surface of the base material. The bonding layer and the conductor layer are sprayed to form the front layer by kinetic energy (1/2 m _{x + 1} V _{x + 1} ² ) when the conductive material is sprayed on the surface of the layer formed by spraying the conductive material. collector according to any one of the kinetic energy ^{_{(1 / 2m x V x 2}} ) than the larger claims 3-4 when.   The current collector according to claim 5, wherein a ratio between an average particle diameter of the conductive material sprayed and an average particle diameter of the conductive material sprayed to form the front layer is 1.2 / 1 or more. .   The current collector according to claim 5, wherein a spraying speed of the conductive material sprayed is higher than a spraying speed of the conductive material sprayed to form the front layer.   The ratio between the spraying speed of the conductive material sprayed and the spraying speed of the conductive material sprayed to form the front layer is 1.33 / 1 or more. The current collector described.   The current collector according to claim 1, wherein the conductive material is sprayed at 150 to 450 m / sec.   The current collector according to claim 1, wherein 90% or more of the surface of the base material is covered with the conductive material.   The current collector according to claim 1, wherein the conductive material is made of at least one of a carbon material, a conductive ceramic, a conductive oxide, and a metal material.   The current collector according to claim 11, wherein the carbon material is at least one of graphite, carbon black, acetylene black, carbon nanotube, and glassy carbon.   The current collector according to claim 12, wherein the graphite is at least one of scaly graphite, artificial graphite, scaly graphite, and earthy graphite.   The current collector according to claim 11, wherein the conductive ceramic is at least one of titanium carbide and titanium nitride.   The current collector according to claim 11, wherein the conductive oxide is at least one of vanadium oxide, titanium oxide, niobium oxide, cobalt oxide, manganese oxide, nickel oxide, silver oxide, zinc oxide, and tungsten oxide.   The current collector according to claim 11, wherein the metal material is at least one of nickel, silver, gold, and platinum. A metal substrate;
A bonding layer formed on the surface of the base material, in which the base material and a conductive material having conductivity are mixed;
A conductor layer formed on the bonding layer and having the conductive material;
A method of manufacturing a current collector for a power storage device having
Forming the bonding layer on the surface of the substrate;
Spraying the conductive material having a particle diameter larger than the particle diameter of the conductive material located on the substrate side of the bonding layer together with a carrier gas on the surface of the bonding layer;
A method for producing a current collector, comprising:   The method for manufacturing a current collector according to claim 17, wherein the bonding layer is formed by spraying the conductive material on a surface of the base material.   The method for manufacturing a current collector according to claim 18, wherein the bonding layer and the conductor layer increase in size as the particle diameter of the conductive material contained increases from the substrate side to the surface side. The bonding layer and the conductor layer are sprayed to form the front layer by kinetic energy (1/2 m _{x + 1} V _{x + 1} ² ) when the conductive material is sprayed on the surface of the layer formed by spraying the conductive material. method for producing a current collector according to any one of the kinetic energy ^{_{(1 / 2m x V x 2}} ) greater claim than 17-19 when.   The current collector according to claim 20, wherein a ratio of an average particle diameter of the conductive material sprayed to an average particle diameter of the conductive material sprayed to form the front layer is 1.2 / 1 or more. Manufacturing method.   The method for manufacturing a current collector according to any one of claims 20 to 21, wherein a spraying speed of the conductive material sprayed is faster than a spraying speed of the conductive material sprayed to form the front layer.   The ratio of the spraying speed of the conductive material sprayed to the spraying speed of the conductive material sprayed to form the front layer is 1.33 / 1 or more. The manufacturing method of the electrical power collector of description.   The method for manufacturing a current collector according to any one of claims 17 to 23, wherein the conductive material is sprayed at 150 to 450 m / sec.   The said base material is a manufacturing method of the electrical power collector in any one of Claims 17-24 with which 90% or more of the surface is coat | covered with the said electrically conductive material.   The method for manufacturing a current collector according to any one of claims 17 to 25, wherein the conductive material is made of at least one of a carbon material, a conductive ceramic, a conductive oxide, and a metal material.   27. The method for producing a current collector according to claim 26, wherein the carbon material is at least one of graphite, carbon black, acetylene black, carbon nanotube, and glassy carbon.   28. The method of manufacturing a current collector according to claim 27, wherein the graphite is at least one of scaly graphite, artificial graphite, scaly graphite, and earth graphite.   27. The method of manufacturing a current collector according to claim 26, wherein the conductive ceramic is at least one of titanium carbide and titanium nitride.   27. The method of manufacturing a current collector according to claim 26, wherein the conductive oxide is at least one of vanadium oxide, titanium oxide, niobium oxide, cobalt oxide, manganese oxide, nickel oxide, silver oxide, zinc oxide, and tungsten oxide.   27. The method of manufacturing a current collector according to claim 26, wherein the metal material is at least one of nickel, silver, gold, and platinum. A current collector manufactured according to any one of claims 1 to 16, or a current collector manufactured by the manufacturing method according to claims 17 to 31;
An electrode active material layer formed on the surface of the current collector;
The electrode characterized by having.   33. The electrode according to claim 32, wherein the electrode active material layer has an electrode active material that can occlude and release ions, can exchange electrons associated with a redox reaction, or can store charges reversibly.   The electrode according to claim 33, wherein the electrode active material is at least one of a metal oxide compound and a radical stabilizing compound.     The metal oxide compound may be at least one of a cobalt oxide, a nickel oxide, a manganese oxide, and an iron olivic acid oxide as a metal oxide compound that can occlude and release lithium ions, or these oxides. The electrode according to claim 34, which is a compound containing a complex.   The electrode according to claim 34, wherein the radical compound is at least one of a compound having a nitroxyl radical, a compound having an oxy radical, and a compound having a nitrogen radical.   37. The electrode according to claim 32, wherein the electrode active material layer is made of a slurry in which the electrode active material is dispersed in an aqueous solvent.   A power storage device comprising the current collector according to claim 1 or the current collector manufactured by the manufacturing method according to claims 17-31.