JP5141951B2 - Current collector manufacturing method and electrode manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a current collector decreasing internal resistance. <P>SOLUTION: The manufacturing method for a current collector comprises: a process of using a base stand retaining by firmly sticking a thin film base material on the surface and firmly sticking and retaining the thin film base material on the surface of the base stand; and an injection process of jetting a mixture of particulate material with a particle size of 1-9 &mu;m and a carrier gas to the thin film base material retained on the base stand. That is, a firmly-joined conductor layer is formed on the surface of the thin film base material so that the particulate material made of a conductive material forming a conductor layer and having a distribution of designated particle sizes is injected on the surface of the thin film base material with aluminum as a major component at high pressure in order to form the conductor layer. The conductor layer made of the conductive material is formed on the surface of the thin film base material since the particulate material injected from a nozzle at high speed enters and diffuses into the thin film base material by breaking through a passive coated film formed on the surface of the thin film base material. The formed conductor layer is firmly joined with diffusion of atoms between the conductor layer and the thin film base material. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

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

  In recent years, development of automobiles with reduced exhaust gas emissions or automobiles that do not emit exhaust gas has been promoted from the viewpoint of solving environmental problems derived from exhaust gas of internal combustion engines. As one of vehicles that reduce exhaust gas emissions, there is a hybrid vehicle that combines an internal combustion engine and an electric motor. An electric vehicle is one of the vehicles that does 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 a power storage device mounted on an automobile is required to be charged and discharged with a large current instantaneously as needed, that is, to have a high output density while being small and lightweight. 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 materials such as electrodes constituting the power storage device.

  A power storage device mounted on a vehicle generally has a configuration in which an electrode body obtained by winding or laminating positive and negative electrodes formed in a sheet shape with a separator interposed therebetween is housed in a case together with an electrolytic solution.

  Examples of the sheet-like electrode include those having a configuration in which an electrode mixture layer containing an active material or the like is formed on the surface of a metal foil as a current collector. Therefore, the influence of electricity exchange between the current collector and the electrode mixture layer on the internal resistance is not limited.

  An aluminum foil may be used as a current collector in the power storage device (for example, a positive electrode current collector 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 ordinary aluminum has a passive film having a large electric resistance. In addition, by driving the power storage device, the current collector made of aluminum is exposed to a high potential, so that the aluminum constituting the current collector reacts with the surrounding electrolyte so that the surface of the current collector has a high resistance. It was confirmed that a film was formed.

  As described above, the power storage device has a problem that the internal resistance increases due to an oxide film or a high resistance film formed on the surface of the current collector made of aluminum. 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 electrolyte is prevented.

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

  Patent Document 4 discloses that an active material of a type corresponding to an adhesion pattern is deposited on a current collector as a large number of particles by an inkjet method.

  Patent Document 5 discloses that the surface of an aluminum foil is polished under an oxygen-free atmosphere to remove a passive film, and an active material layer is formed under an oxygen-free atmosphere.

  Patent Document 6 discloses a technique for forming a graphite lubricating layer by a direct pressure blasting apparatus, although it is not related to the power storage device.

Patent Document 7 discloses a technique for forming an electrode active material layer by gas deposition and relieving stress when lithium is inserted.
JP 7-22606 A Japanese Patent Laid-Open No. 2002-298753 JP 2004-63156 A JP 2005-11657 A JP 2000-243383 A JP-A-2005-144666 JP 2006-156248 A Japanese Patent Laid-Open No. 11-300619 JP 2000-326229 A Japanese Patent Laid-Open No. 2001-247879 JP 2005-2461 A

  However, since the current collectors disclosed in Patent Documents 1 to 4 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.

  The method disclosed in Patent Document 5 has a problem that the active material layer and the aluminum foil (current collector) are bonded only by the anchor effect, but the bonding force is weak, although the passive film is removed. . And the oxidation of the exposed part of the aluminum of the manufactured electrode occurred, and there was a problem that the internal resistance was increased.

  The technique described in Patent Document 6 is a technique for forming a lubricating layer, and when applied to a thin film current collector as it is, damage to the current collector, such as generation of a strain or breakage, is large. It was difficult to form a film on the skin.

  The technique described in Patent Document 7 has a problem in that the working efficiency is low because the atmosphere needs to be evacuated during film formation.

  The present invention has been made in view of the above circumstances, and provides a current collector capable of reducing internal resistance when applied to a battery, a method for producing an electrode, and an apparatus capable of producing such a current collector. It is a problem to be solved.

  (1) In order to solve the above-mentioned problems, the present inventors have intensively studied, and a bonding layer in which aluminum and a conductive material having conductivity are mixed is formed on the surface of an aluminum current collector. It was discovered that a power storage device with low internal resistance can be provided by employing a novel current collector in which a conductive layer having a conductive material is formed on a bonding layer. The present inventors have devised a manufacturing method and a manufacturing apparatus suitable for providing the new current collector. An oxide film is usually formed on the surface of the metal, and this method and apparatus are also effective for the oxide film. Therefore, this method and apparatus can be applied to metals other than aluminum.

That is, the manufacturing method of the current collector of the present invention that solves the above-mentioned problems is a conductor including a conductive material comprising a thin film substrate made of metal (particularly aluminum or aluminum alloy) and titanium carbide formed on the surface thereof. A method of manufacturing a current collector for a power storage device having a layer,
With a thickness of the thin film substrate is made of aluminum foil or aluminum alloy foil is 50μm or less, using a base to hold in close contact with the film substrate on the surface,
A step of closely holding the thin film substrate on the surface of the base;
A mixture of a fine particle material formed from the conductive material having a particle diameter of 1 μm to 9 μm and a carrier gas is sprayed from the nozzle onto the thin film substrate held on the base , and scanning at the time of the spraying And a jetting step of forming irregularities on the surface of the thin film substrate by setting the speed to 4 mm / second or less .

  That is, for the purpose of forming a conductor layer, a fine particle material formed of a conductive material forming the conductor layer and having a predetermined particle size distribution is sprayed onto the surface of a thin film base material mainly composed of aluminum at high pressure. Thus, a strongly bonded conductor layer can be formed on the surface of the thin film substrate.

  The fine particle material sprayed from the nozzle at high speed penetrates the passive film formed on the surface of the thin film substrate and enters and diffuses into the thin film substrate to form a conductive layer made of a conductive material on the surface of the thin film substrate. To do. The formed conductor layer is firmly bonded to the thin film substrate by the diffusion of atoms.

  Moreover, since the fine particle material is jetted in a state where the thin film base material is tightly held on a strong base, it is possible to suppress the generation of distortion resulting from the collision of the fine particle material as much as possible.

  Although devices disclosed in Patent Documents 8 and 9 are disclosed as devices for injecting from a nozzle, the technologies disclosed in Patent Documents 8 and 9 do not aim at film formation but relate to different technical fields.

And in the manufacturing method of the current collector of the present invention, it has a gas suction means having an opening for sucking gas,
One end of the base has a suction port that opens to the surface where the base is closely held, and the other end has a connection port that is connected to the opening of the gas suction means so that internal gas is sucked. The gas suction path to be formed is formed,
The thin film substrate is preferably adsorbed on the surface of the base by performing gas suction from the suction port opened on the surface of the base by the gas suction means.

  Holding of the thin film substrate by suction can securely hold the thin film substrate on the surface of the base, and it is easy to remove the thin film base from the base.

  Furthermore, a stronger bond is realized by having a bonding layer formed by diffusing the conductive material from the surface of the thin film substrate between the thin film substrate and the conductor layer. It is desirable because it is possible. According to the above-described method for manufacturing a current collector of the present invention, the conductor layer and the thin film substrate are firmly bonded by diffusion, but the diffusion proceeds to such an extent that the bonding layer is formed. As a result, stronger bonding can be realized.

  The conductive material is preferably selected from the group consisting of carbon materials, conductive ceramics, conductive oxides, metal materials, and conductive resin materials. The carbon material preferably includes a material selected from the group consisting of graphite, carbon black, acetylene black, and carbon nanotubes. The conductive ceramic desirably contains titanium carbide or titanium nitride. The conductive oxide preferably includes a material selected from the group consisting of vanadium oxide, titanium oxide, niobium oxide, cobalt oxide, manganese oxide, nickel oxide, silver oxide, zinc oxide, and tungsten oxide. The metal material preferably includes a material selected from the group consisting of nickel, silver, gold, and platinum.

  In order to reliably perform the bonding between the formed conductor layer and the thin film substrate and the removal of the passive film on the surface of the thin film substrate, the speed of the fine particle material ejected from the nozzle is 200 m / second. It is desirable that it is ˜450 m / sec.

  (2) A method of manufacturing an electrode of the present invention that solves the above problem is a method of manufacturing an electrode having a thin-film current collector and an electrode active material layer formed on the surface of the current collector, The current collector is manufactured by the method for manufacturing a current collector described above.

Apparatus for manufacturing other current collector of the present invention for solving the above SL problem, the current collector for a power storage device having a conductive layer containing a metal thin film substrate and a conductive material formed on the surface thereof An apparatus for manufacturing
A base that holds the thin film substrate in close contact with the surface;
An injection means for injecting from a nozzle a mixture of a fine particle material formed from the conductive material and a carrier gas having a particle diameter of 1 μm to 9 μm onto the thin film substrate held on the base. Is desirable .

  The method for producing a current collector of the present invention has the above-described configuration, so that the passive film existing on the surface of the thin film substrate can be removed while avoiding damage to the thin film substrate as much as possible, and at the same time covered with the conductor layer. It becomes possible. Furthermore, by appropriately selecting the conductive material constituting the conductor layer, it is possible to minimize the increase in internal resistance due to the resistance on the surface of the manufactured current collector.

  That is, the current collector manufactured by the method for manufacturing a current collector of the present invention has a surface formed by a conductor layer having a conductive material having conductivity, so that a power storage using an organic electrolyte is performed. When the electrode of the device is formed, the thin film substrate is not directly exposed to the electrolytic solution, and a high-resistance film is not formed, so that an increase in internal resistance due to the passive film is suppressed and output characteristics are improved.

  In the current collector of the present invention, the oxide film on the surface is removed when the bonding layer in which the conductive material is mixed is formed on the surface of the thin film substrate made of aluminum or the like. That is, in the current collector of the present invention, the increase in internal resistance due to the oxide film on the surface of the thin film substrate is suppressed.

  Furthermore, since the method for producing a current collector of the present invention sprays the fine particle material onto the thin film substrate in a state in which the current collector is in close contact with the base surface, the thin film substrate is not deformed by the collision of the fine particle material, There is an advantage that the generation of distortion of the thin film substrate can be reduced as much as possible.

(Current collector manufacturing method and manufacturing apparatus)
Hereinafter, a method for manufacturing a current collector of the present invention (and a manufacturing apparatus. The manufacturing apparatus will be omitted in the description of the manufacturing method), based on the embodiments. Examples of the current collector that can be manufactured by the current collector manufacturing method of the present embodiment include a non-aqueous battery such as a lithium secondary battery, and a current collector that is used for an electrode of an electric double layer capacitor. .

  The method for producing a current collector of the present embodiment is a method for producing a current collector for a power storage device having a metal thin film substrate and a conductor layer containing a conductive material formed on the surface thereof. It is desirable that a bonding layer be formed between the conductor layer and the thin film substrate. The bonding layer is a layer formed by diffusing a conductive material from the surface of the thin film substrate. Since the bonding layer has the constituent components of both the thin film substrate and the conductor layer, the bonding layer has a high affinity for both, and the presence of the bonding layer can strengthen the bonding between the two.

  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, a high effect of bonding the base material and the conductor layer is exhibited.

  The thin film base is a thin film member made of metal (for example, aluminum, aluminum alloy, nickel, nickel alloy, stainless steel alloy). The metal forming the thin film substrate is selected according to the power storage device to which the final current collector is applied. As the thin film substrate, a current collector that has been conventionally employed can be employed as it is. The form of the thin film base material is not particularly limited except that it is in the form of a thin film, but it is desirable that the thin film base material is thin as long as it has the required strength from the viewpoint of improving the volume energy density of the applied power storage device. For example, it is preferably 50 μm or less, and more preferably 30 μm or less. According to the manufacturing method of the present embodiment, a conductor layer can be formed on the surface even with such a thin thin film substrate.

  The conductive material forming the conductive layer desirably includes a material selected from the group consisting of carbon materials, conductive ceramics, conductive oxides, metal materials, and conductive resin materials. The carbon material is selected from the group consisting of graphite (as graphite, natural graphite (especially earth graphite, massive graphite, etc.) and artificial graphite can be used), carbon black, acetylene black, and carbon nanotubes. It is desirable to include materials. As the conductive ceramic, it is desirable to include titanium carbide or titanium nitride. The conductive oxide desirably includes a material selected from the group consisting of vanadium oxide, titanium oxide, niobium oxide, cobalt oxide, manganese oxide, nickel oxide, silver oxide, zinc oxide, and tungsten oxide. The metal material desirably includes a material selected from the group consisting of nickel, silver, gold, and platinum. These materials can be used alone or in any combination. When used in combination, they may be mixed at the molecular level or mixed at the primary or secondary particle level. In addition, the case where the same material as the material constituting the thin film substrate is adopted as the metal material to be a conductive material (for example, a nickel conductive material is sprayed onto a nickel thin film substrate) is also included. However, even in that case, the effect of removing the oxide film on the surface of the thin film substrate can be expected.

  The manufacturing method of the current collector of the present embodiment includes a step of closely holding the thin film substrate on the base and a spraying step of spraying the fine particle material formed from the conductive material onto the thin film substrate.

  The base is a member that holds the thin film substrate in close contact with the surface, and is used for the spraying process in a state of being held in close contact. The base is preferably made of a material that does not deform the surface that holds the thin film substrate in close contact during the spraying process. This is because, when the base is deformed, the thin film base material held in close contact may be deformed to cause distortion. The base can be made of, for example, metal or ceramics.

  There are no particular limitations on the method of closely holding the thin film substrate on the surface of the base, for example, a method of sucking and holding the gas between the surface of the base and the thin film substrate, For example, a method of holding with a force of. As a method for sucking and holding the gas, it is desirable to use a base on which a suction path is formed. The suction path has one or two or more suction ports that open on the surface that holds the thin film substrate in close contact, and is open to a surface other than the surface that is connected to the suction port and holds the thin film substrate in close contact. Is a through-hole having the other end and communicating between the suction port and the opening. By forming one or more suction paths, it is desirable to form one or more suction ports on the surface on which the thin film base material is closely held. By sucking the gas from the opening of the suction path, the gas is sucked from the suction port, and the thin film substrate is held in close contact with the surface.

  As the base on which the suction path is formed, porous materials (made of ceramics, resin, etc.) or mesh members (gas is sucked through the mesh members to bring the thin film substrate into close contact with the mesh members) can be used. It is.

  Here, when the thin film substrate is held in close contact with the base surface by gas suction, the thin film substrate is distorted by entering the suction port by the gas suction. Since the degree of distortion generated increases as the size of the suction port (opening diameter) increases, the size of the suction port formed on the base surface depends on the material forming the thin film substrate and the thickness of the thin film substrate. The gas is appropriately controlled according to the degree of gas suction (degree of vacuum). Specifically, a suction port size that allows (or less than) the strain generated in the thin film substrate to be acceptable is employed. In addition, by forming a plurality of gas suction paths, it is possible to reduce the degree of suction of gas (degree of vacuum), and the possibility of deforming the thin film substrate can be reduced.

  The gas suction means that is a means for sucking gas from the opening of the suction path is not particularly limited as long as the gas can be sucked, and a general pump such as a vacuum pump can be adopted.

  The spraying step is a step of spraying the fine particle material onto the thin film substrate that is closely held on the base surface. The particulate material is carried by a carrier gas and is jetted as a mixture with the carrier gas. The fine particle material has a particle diameter of 1 μm to 9 μm and is made of a conductive material. When the particle size of the fine particle material is less than 1 μm, the fine particles injected to the thin film substrate may rebound when injected as a mixture with a carrier gas. On the other hand, if it exceeds 9 μm, the thin film substrate may be peeled off by the collision of the fine particles.

  The fine particle material preferably has a speed of 200 m / sec to 450 m / sec when ejected from the nozzle. Further, the particulate material is controlled so as to be ejected to a certain range, and it is desirable to move the range. Although it does not specifically limit as a speed which moves an injection range, About 1 mm / second-50 mm / second are employable.

  The speed of the fine particle material to be ejected is not particularly limited, but the lower limit may be 100 m / s, 150 m / s, 200 m / s, 250 m / s, 300 m / s, 350 m / s, and the upper limit is 500 m. / S, 450 m / s, 400 m / s, 350 m / s, 300 m / s, 250 m / s, etc. can be employed.

  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, to achieve the fine particle injection speed, about 0.25 MPa to 1.00 MPa is employed. Is desirable.

(Method for manufacturing electrode)
The electrode manufacturing method of the present invention is a method for manufacturing an electrode having a thin-film current collector and an electrode active material layer formed on the surface of the current collector, and the current collector is the above-described current collector. It is manufactured by the manufacturing method of. This electrode 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. Regarding the current collector and its manufacturing method, the above-described configuration can be employed as it is, and further description thereof is omitted.

  The electrode active material layer has an active material. In addition to the active material, a conductive material and a binder can be included. An active material is a substance that causes an electrode reaction when the electrode is used as an electrode of a power storage device. The electrode reaction is not limited, but is a reaction in which ions are occluded / released in the crystal structure like the electrode reaction of a lithium battery, or a reaction that exchanges electrons associated with a redox reaction like a radical battery. The reaction of forming an electric double layer on the surface thereof can be given as in the case of an electric double layer capacitor.

  The active material has at least one type of electrode reaction of 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 supports ions when a power storage device is configured. There is no particular limitation as long as the substance is generated. 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 is a compound having an unpaired electron, and the unpaired electron is involved in 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.

  The power storage device manufactured using the electrode described above is not particularly limited. For example, general configurations such as an electrolytic solution, a case, and a separator can be adopted in addition to the electrodes.

・ Test 1
The relationship between the carrier gas and the injection speed when titanium carbide particles (average particle size 1 μm), graphite particles (average particle size 2.0 μm) and titanium nitride particles (average particle size 1.0 μm) are employed as the fine particle materials, respectively. investigated.

  Nitrogen was used as a carrier gas, and the injection speed of each fine particle material was measured when the pressure was 0.25 MPa, 0.50 MPa, 0.75 MPa, and 1.00 MPa. The injection conditions are as follows: the nozzle used is a straight tube with an inner diameter of 1 mm, a flat tip, and the fine particles are sprayed when the substrate is placed so that the distance from the tip is 1 mm. The speed 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. The results are shown in Table 1.

  As is apparent from Table 1, by controlling the carrier gas pressure in the range of 0.25 MPa to 1.00 MPa, the injection speed could be controlled from a little less than 200 m / s to about 450 m / s.

  And after the test, when the cross section of the board | substrate was observed, it turned out that the conductor layer formed from the material according to the kind of each injected fine particle material is formed in the surface of the board | substrate. The thickness of the conductor layer was not greatly affected by the type of material constituting the fine particle material, and was formed to have the same thickness at the same jetting speed.

・ Test 2
As examples of the present invention, a method for forming a conductor layer made of titanium carbide as a conductive material on the surface of an aluminum foil as a thin film substrate was examined under various conditions.

-Formation of conductor layer on aluminum foil surface (basic operation)
An aluminum foil (thickness: 15 μm) was vacuum sucked from the back surface of the base (having a suction path having a suction port on the surface) and fixed to the surface (adhesion holding step). Titanium carbide particles as a fine particle material with an average particle diameter of 1.0 μm are accelerated on a fixed aluminum surface by flowing them in an air stream using nitrogen gas at a pressure of 0.50 MPa. A conductor layer which is a film containing titanium carbide was formed by colliding with the density (injection step). The average flow rate of titanium carbide during injection was 280 m / sec, and the distance between the nozzle and the aluminum foil surface was 1 mm. After the nozzle is scanned from one end to the other end of the treated area of the aluminum foil, the nozzle is shifted by 1.0 mm in a direction perpendicular to the scanning direction, and is continuously scanned while being sequentially repeated. A conductor layer was formed.

  The titanium carbide particles ejected from the nozzle spread evenly as a circle having a diameter of about 1.2 mm and collided with the aluminum foil. Since the size of shifting the nozzle for each scan is 1.0 mm, the region where the titanium carbide particles collide by about 0.1 mm for each scan is overlapped.

・ Nozzle scanning speed The nozzle that injects titanium carbide particles keeps the distance from the aluminum foil constant (1 mm), while changing the speed (scanning speed) to move in parallel to the spreading direction of the aluminum foil. The state of the conductor layer formed at the time was evaluated. The scanning speed was evaluated in four ways of 4 mm, 10 mm, 20 mm, and 30 mm per second. The state of the conductor layer was evaluated by observing the cross section with a TEM. The results are shown in FIG.

  As is clear from FIG. 1, it was found that the surface of the aluminum foil after treatment became smooth as the scanning speed increased. This is presumed to be due to the fact that the time (amount) during which the titanium carbide particles are ejected decreases as the scanning speed increases when considered per unit area. That is, if the time for which the titanium carbide particles are ejected is short, it is considered that the deformation of the surface due to the collision of the titanium carbide particles is reduced. Further, as apparent from FIG. 1, it was found that the thickness of the formed conductor layer is not greatly different even when the scanning speed is changed (for example, in the range of 30 mm / second or less as in this embodiment).

  Therefore, it is effective to increase the scanning speed when it is not desired to form unevenness on the surface, and to lower the scanning speed when it is desired to form unevenness on the surface. For example, it was found that unevenness can be formed on the surface by setting the scanning speed to 10 mm / second or less, and further to 4 mm / second or less. It was also found that the surface can be smoothed by setting the scanning speed to 20 mm / second or more, and further to 30 mm / second or more.

-Film resistance before and after charging The current collector of the example in which the conductor layer was formed on the surface was manufactured by injecting titanium carbide particles onto the surface of the aluminum foil at a scanning speed of 30 mm / sec. An aluminum foil having no conductor layer formed on the surface was used as a current collector of a comparative example. The film resistance before and after charging was measured for an electrode corresponding to the positive electrode of a lithium secondary battery manufactured using the current collectors of the examples and comparative examples.

The electrodes to be used for the test were the current collectors of Examples and Comparative Examples. The positive electrode mixture paste was applied to both surfaces of the current collector, dried, and then pressed to form a positive electrode composite on both surfaces of the current collector. The electrode on which the material layer was formed was completed. The positive electrode mixture paste includes lithium nickel oxide (LiNiO ₃ ) as a positive electrode active material, acetylene black (Denka Black HS100, manufactured by Denki Kagaku Kogyo) as a conductive material, and polyvinylidene fluoride (PVDF) as a binder. It was prepared by dispersing in N-methylpyrrolidone as a medium. LiNiO ₃ : HS100: PVDF was 85: 10: 5.

  The charging operation and the measurement of the film resistance were performed as follows using the apparatus shown in FIG. As the test electrode 1 shown in FIG. 2, the electrodes of Examples and Comparative Examples were adopted. Using the test electrode 1 as a working electrode, the film resistance was measured using a counter electrode 2 and a reference electrode 5 made of metallic lithium. The film resistance was measured by measuring the current value when various voltages were applied, and the resistance value derived from the film was calculated from the measured voltage and current value.

  The film resistance was measured twice before and after the charging operation for each test electrode. As charging conditions, a voltage of 4.1 V was applied between the test electrode and the counter electrode for 2 hours.

As the electrolyte 3, a solution obtained by dissolving LiPF ₆ as a supporting electrolyte at a concentration of 1 mol / L in a non-aqueous solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 3: 7 was used. . The results are shown in FIG.

  As is apparent from FIG. 3, the test electrode employing the current collector of the comparative example has an increased film resistance value when charged. This is presumably because the electrolyte reacted with the surface of the aluminum foil constituting the current collector to form a film having high electrical resistance.

  And the test electrode which employ | adopted the electrical power collector of the Example hardly recognized the change in the magnitude | size of film resistance before and behind charge. Furthermore, it became clear that the value of the film resistance before charging was extremely small as compared with the test electrode of the comparative example. This is because the surface of the aluminum foil constituting the current collector in the test electrode of the comparative example is formed with a passive layer having a large electric resistance, whereas the current collector in the test electrode of the example is It is considered that the surface of the aluminum foil to be formed is derived from the presence of a conductor layer formed from titanium carbide. In other words, titanium carbide has a lower electrical resistance than a passive state formed on the surface of the aluminum foil and a low reactivity with the electrolyte, and in the embodiment adopting a current collector in which a conductor layer made of titanium carbide is formed. It can be assumed that the test electrode can maintain a low film resistance before and after charging.

  As a result of measuring the output characteristics by a conventional method, it was found that the output upper limit current of the test battery of the example is 70 mA, which is about 1.16 times larger than the output upper limit current of the test battery of the comparative example. That is, it was confirmed that the output density was improved by forming a conductor layer on the surface of the current collector.

It is the SEM photograph which observed the cross section of the conductor layer formed when the scanning speed of a nozzle was changed in an Example. It is the schematic of the measuring apparatus used for the measurement of the film | membrane resistance of an electrode in an Example. It is a graph which shows the result of having measured the film resistance before and behind charge / discharge of the test electrode of an Example and a comparative example.

Claims (5)

A method for producing a current collector for a power storage device having a metal thin film substrate and a conductor layer containing a conductive material made of titanium carbide formed on the surface of the metal thin film substrate,
With a thickness of the thin film substrate is made of aluminum foil or aluminum alloy foil is 50μm or less, using a base to hold in close contact with the film substrate on the surface,
A step of closely holding the thin film substrate on the surface of the base;
A mixture of a fine particle material formed from the conductive material having a particle diameter of 1 μm to 9 μm and a carrier gas is sprayed from the nozzle onto the thin film substrate held on the base , and scanning at the time of the spraying And a jetting step of forming irregularities on the surface of the thin film substrate by setting the speed to 4 mm / second or less . Having gas suction means with an opening for sucking gas;
One end of the base has a suction port that opens to the surface where the base is closely held, and the other end has a connection port that is connected to the opening of the gas suction means so that internal gas is sucked. The gas suction path to be formed is formed,
2. The method of manufacturing a current collector according to claim 1, wherein the thin film substrate is adsorbed on the surface of the base by performing gas suction from the suction port opened on the surface of the base by the gas suction means. The current collector according to claim 1, further comprising a bonding layer formed by diffusing the conductive material from the surface of the thin film base material between the thin film base material and the conductive material layer. Manufacturing method. The method for producing a current collector according to any one of claims 1 to 3 , wherein a speed of the fine particle material ejected from the nozzle is 200 m / sec to 450 m / sec. A method for producing an electrode having a thin film current collector and an electrode active material layer formed on the surface of the current collector,
The said collector is manufactured with the manufacturing method in any one of Claims 1-4 , The manufacturing method of the electrode characterized by the above-mentioned.