TW201324929A - Secondary-battery current collector, secondary-battery cathode, secondary-battery anode, secondary battery and production method thereof - Google Patents

Abstract

A secondary-battery current collector comprising an aluminum foil and a film containing an ion-permeable compound and carbon fine particles formed thereon or a secondary-battery current collector comprising an aluminum foil, a film containing an ion-permeable compound and carbon fine particles formed thereon as the lower layer, and a film containing a binder, carbon fine particles and a cathodic electroactive material formed thereon as the upper layer, a production method of the same, and a secondary battery having the current collector are provided.

Description

Battery current collector, battery positive electrode, battery negative electrode, battery and manufacturing method thereof

The present application claims the priority of Japanese Patent Application No. 2005-34639, filed on Feb. The disclosures form a direct part of this application.

The present invention relates to a current collector for a lithium ion battery, a positive electrode for a storage battery, a negative electrode for a storage battery, a storage battery, and the like, and a high performance material for a lithium ion secondary battery which can provide excellent rapid charge and discharge characteristics.

Lithium-ion batteries, which are high-performance batteries, have a high energy density and are currently being extended to mobile phones or notebook PCs for video cameras and other applications. Among these lithium ion batteries, in general, lithium cobaltate or lithium manganate is used for the positive electrode active material, and graphite is used for the negative electrode. Further, a separator made of a porous sheet such as polypropylene or polyethylene is formed by dissolving an organic solution of a lithium salt such as a vinyl carbonate solution of lithium hexafluorophosphate (LiPF ₆ ) as an electrolytic solution.

More specifically, the positive electrode of a lithium ion secondary battery is generally a lithium foil of a positive electrode active material, lithium cobalt oxide or lithium manganate, and electron-conducting carbon fine particles for transporting electrons therein, and a metal foil having a current collecting effect. It was established by being fixed. In this case, the metal foil to be used is generally aluminum, and the binder used for immobilizing the positive electrode active material and the carbon fine particles is polyvinylidene chloride (PVDF) or polytetrafluoroethylene (PTFE).

In recent years, such high-performance batteries have been extremely active in the field of essential power such as automobiles. As a result, problems that were unexpected in the past small batteries have also occurred.

One is the rapid charge and discharge characteristics. For the necessary power, a large amount of current is necessary. Therefore, the battery capacity is exhausted and it is necessary to recharge. When the charging time is set to be long, the battery cannot be used in the meantime, and charging has to be completed as fast as possible with a large current. The discharge performance and charging performance of such a large current value are called rapid charge and discharge characteristics, and are indicators of important performance of the battery.

When performing rapid charge and discharge, as described above, it is necessary to increase the current value. However, when the lithium ion battery of the current state is charged and discharged with a large current, the capacity reduction (initial battery capacity retention rate) at the time of charging and discharging is repeated, which may cause an extreme decline. That is, when the battery is repeatedly charged and discharged with a large current, the power is lowered. More specifically, the current state of charge and discharge can be performed at 1 C (the battery capacity can be charged and discharged for 1 hour), but it is almost impossible to charge and discharge at 20 C (the battery capacity is a current value that can be charged and discharged for 1 hour). 20 times the current value). In order to improve such an unsuitable situation, there are numerous attempts in the following literature.

JP-A-2001-266850

Special fair 7-121053

Patent No. 1,989,293

The 45th battery seminar (Heisei 16) 3C18

However, the techniques described in each of the above documents cannot be sufficiently improved, which is not suitable.

[disclosure of invention]

In view of the above problems, the present invention has an object of providing a current collector and a storage battery for a lithium secondary battery which can perform rapid charge and discharge and have a high initial battery capacity retention rate in a high current value.

In order to achieve the above object, the working colleagues of the present invention have found that in the positive electrode structure, the positive electrode current collecting and the electronically conductive carbon microparticles share the electron conductive positive electrode current collection by the ion permeability compound. The body structure can solve the above problems and complete the present invention. That is, the present invention relates to the following.

[1] A battery current collector comprising an aluminum foil or a copper foil comprising a film containing an ion-permeable compound and carbon fine particles.

[2] A battery current collector comprising an aluminum foil or a copper foil comprising a film containing a compound which is not swellable with respect to an organic solvent and carbon fine particles.

[3] A current collector for a battery, characterized in that it is provided A compound which is not peeled off in an organic solvent peeling test, and an aluminum foil or a copper foil which is a film of carbon fine particles.

[4] A battery current collector comprising an aluminum foil or a copper foil containing a compound which is not peeled off in a tape peeling test (JIS D0202-1988) and a film of carbon fine particles.

[5] A positive electrode for a storage battery comprising a film containing a compound having ion permeability and carbon fine particles, and an upper layer comprising an aluminum foil containing a film of a binder, carbon particles, and a positive electrode active material.

[6] A positive electrode for a storage battery comprising a film containing a compound having no swelling property with respect to an organic solvent and carbon fine particles, and an upper layer comprising an aluminum foil containing a film of a binder, carbon particles, and a positive electrode active material.

[7] A positive electrode for a storage battery, characterized in that the lower layer is provided with a film containing a compound which is not peeled off in a peeling test using an organic solvent and carbon fine particles, and the upper layer is provided with a film containing a binder, carbon fine particles and a positive electrode active material. Made into.

[8] A positive electrode for a storage battery, characterized in that the lower layer is provided with a film containing a compound which does not peel off in a tape peeling test (JIS D0202-1988) and carbon fine particles, and the upper layer is provided with a film containing a binder, carbon fine particles, and a positive electrode active material. Made of aluminum foil.

[9] A negative electrode for a storage battery comprising a film containing a compound having ion permeability and carbon fine particles in a lower layer, and a copper foil comprising a film containing a binder, carbon particles, and a negative electrode active material in the upper layer.

[10] A negative electrode for a storage battery, characterized by comprising a lower layer The film having no swelling property with respect to the organic solvent and the film of the carbon fine particles is formed of a copper foil containing a film of a binder, carbon fine particles, and a negative electrode active material.

[11] A negative electrode for a storage battery, characterized in that the lower layer is provided with a film containing a compound which does not peel off in a peeling test using an organic solvent and carbon fine particles, and the upper layer is provided with a film containing a film of a binder, carbon fine particles and a negative electrode active material. Made of foil.

[12] A negative electrode for a storage battery comprising a film containing a compound which does not peel off in a tape peeling test (JIS D0202-1988) and carbon fine particles, and a film containing a binder, carbon fine particles, and a negative electrode active material in the upper layer. Made of copper foil.

[13] A positive electrode for a storage battery comprising an aluminum foil comprising a film containing an ion-permeable compound, carbon fine particles, and a positive electrode active material.

[14] A positive electrode for a storage battery comprising an aluminum foil comprising a film containing a compound which is non-swellable with respect to an organic solvent, carbon fine particles, and a positive electrode active material.

[15] A positive electrode for a storage battery comprising an aluminum foil comprising a film containing no compound which is not peeled off in a peeling test using an organic solvent, carbon fine particles, and a positive electrode active material.

[16] A positive electrode for a storage battery comprising an aluminum foil containing a film which does not peel off in a tape peeling test (JIS D0202-1988), a carbon fine particle, and a positive electrode active material.

[17] A negative electrode for a storage battery, characterized in that it is provided with a separator A copper foil of a film of a sub-permeable compound, carbon microparticles, and a negative electrode active material.

[18] A negative electrode for a storage battery comprising a copper foil comprising a film containing no swelling property with respect to an organic solvent, carbon fine particles, and a negative electrode active material.

[19] A negative electrode for a storage battery comprising a copper foil comprising a film which is not peeled off in a peeling test using an organic solvent, a film of carbon fine particles and a negative electrode active material.

[20] A negative electrode for a storage battery comprising a copper foil comprising a film which does not peel off in a tape peeling test (JIS D0202-1988), a carbon fine particle, and a negative electrode active material.

[21] The battery current collector according to any one of the above [1], wherein the carbon microparticles are in the form of needles or rods.

[22] The positive electrode for a storage battery according to any one of the above [5], wherein the carbon microparticles are in the form of a needle or a rod.

[23] The negative electrode for a storage battery according to any one of the above-mentioned, wherein the carbon microparticles are in the form of a needle or a rod.

[24] A method for producing a current collector for a battery, characterized in that a film containing an ion-permeable compound and carbon fine particles is applied onto an aluminum foil or a copper foil to form a film.

[25] A method for producing a current collector for a storage battery, characterized in that a film containing a compound having no swelling property with respect to an organic solvent and carbon fine particles is applied onto an aluminum foil or a copper foil to form a film.

[26] A method for producing a current collector for a storage battery, characterized in that a film containing a compound which is not peeled off in a peeling test using an organic solvent and carbon fine particles is applied onto an aluminum foil or a copper foil to form a film.

[27] A method for producing a current collector for a battery, characterized in that a film containing a compound which does not peel off in a tape peeling test (JIS D0202-1988) and carbon fine particles is applied onto an aluminum foil or a copper foil. Membrane.

[28] A method for producing a positive electrode for a storage battery, characterized in that a film containing an ion-permeable compound and a carbon fine particle is applied to an aluminum foil, and then a binder, a carbon fine particle, and a positive electrode active material are dispersed and dissolved thereon. In the case of a solvent, a film is formed.

[29] A method for producing a positive electrode for a storage battery, characterized in that a film containing a compound which is not swollen with respect to an organic solvent and carbon fine particles is applied to an aluminum foil, and then a binder, carbon fine particles, and a positive electrode active material are applied thereon. Disperse and dissolve in the solvent to form a film.

[30] A method for producing a positive electrode for a storage battery, characterized in that a film containing a compound which is not peeled off in a peeling test using an organic solvent and carbon fine particles is applied to an aluminum foil, and then a binder, carbon is applied thereon. When the fine particles and the positive electrode active material are dispersed and dissolved in a solvent, a film is formed.

[31] A method for producing a positive electrode for a storage battery, characterized in that a film containing a compound which does not peel off in a tape peeling test (JIS D0202-1988) and a carbon fine particle is applied to an aluminum foil, and then a binder is applied thereon. The carbon microparticles and the positive electrode active material are dispersed and dissolved in a solvent to form a film.

[32] A method for producing a negative electrode for a storage battery, characterized in that A film having an ion-permeable compound and a carbon microparticle is applied to a copper foil, and then a binder, a carbon microparticle, and a negative electrode active material are dispersed and dissolved in a solvent to form a film.

[33] A method for producing a negative electrode for a storage battery, characterized in that a film containing a compound having no swelling property with respect to an organic solvent and carbon fine particles is applied to a copper foil, and then a binder, carbon fine particles, and a negative electrode are applied thereon. When the active material is dispersed and dissolved in a solvent, a film is formed.

[34] A method for producing a negative electrode for a storage battery, characterized in that a film containing a compound which is not peeled off in a peeling test using an organic solvent and a carbon fine particle is applied to a copper foil, and then a binder is applied thereon. When the carbon fine particles and the negative electrode active material are dispersed and dissolved in a solvent, a film is formed.

[35] A method for producing a negative electrode for a storage battery, characterized in that a film containing a compound which does not peel off in a tape peeling test (JIS D0202-1988) and a carbon fine particle is applied to a copper foil, and then coated thereon to be bonded. The agent, the carbon fine particles, and the negative electrode active material are dispersed and dissolved in a solvent to form a film.

[36] A method for producing a positive electrode for a storage battery, characterized in that a compound having ion permeability, carbon fine particles, and a positive electrode active material are dispersed and dissolved in a solvent, and are applied onto an aluminum foil to form a film.

[37] A method for producing a positive electrode for a storage battery, characterized in that a compound which does not swell with respect to an organic solvent, carbon fine particles, and a positive electrode active material are dispersed and dissolved in a solvent, and are applied to an aluminum foil to form a film.

[38] A method for producing a positive electrode for a storage battery, characterized in that a compound which does not peel off in a peeling test using an organic solvent, carbon fine particles, and a positive electrode active material are dispersed and dissolved in a solvent, and are applied to an aluminum foil and dried. Form a film.

[39] A method for producing a positive electrode for a storage battery, characterized in that a compound which does not peel off in a tape peeling test (JIS D0202-1988), carbon fine particles, and a positive electrode active material are dispersed and dissolved in a solvent, and are applied to an aluminum foil and dried. Form a film.

[40] A method for producing a negative electrode for a storage battery, characterized in that a compound having ion permeability, carbon fine particles, and a negative electrode active material are dispersed and dissolved in a solvent, and coated on a copper foil to form a film.

[41] A method for producing a negative electrode for a storage battery, characterized in that a compound having no swelling property with respect to an organic solvent, carbon fine particles, and a negative electrode active material are dispersed and dissolved in a solvent, and are applied onto a copper foil to form a film.

[42] A method for producing a negative electrode for a storage battery, characterized in that a compound which does not peel off in a peeling test using an organic solvent, carbon fine particles, and a negative electrode active material are dispersed and dissolved in a solvent, and are applied to a copper foil and dried to form a film. Membrane.

[43] A method for producing a negative electrode for a storage battery, characterized in that a compound which does not peel off in a tape peeling test (JIS D0202-1988), a carbon fine particle, and a negative electrode active material are dispersed and dissolved in a solvent, and are applied to a copper foil. Dry to form a film.

[44] A method for producing a secondary battery, characterized in that in the battery manufacturing method in which the organic electrolytic solution is impregnated into a laminate in which the positive electrode, the separator, and the negative electrode are stacked in this order, the above [5] to [8], [ The positive electrode described in any one of items 13 to [16].

[45] A battery characterized in that an organic electrolyte is impregnated in In the battery of the laminate in which the positive electrode, the separator, and the negative electrode are stacked in this order, the positive electrode described in any one of the above [5] to [8], [13] to [16] is used.

[46] A method for producing a secondary battery, characterized in that in the battery manufacturing method in which the organic electrolytic solution is impregnated with the laminated layer in the order of the positive electrode, the separator, and the negative electrode, the above [9] to [12] are used. The negative electrode according to any one of [17] to [20].

[47] A storage battery characterized by using the above [9] to [12], [17] to [20] in a battery in which an organic electrolytic solution is impregnated with a laminate in which the positive electrode, the separator, and the negative electrode are stacked in this order. The negative electrode described in any one of the items.

[24] The positive electrode for a storage battery according to any one of the above [5], wherein the positive electrode active material contains lithium cobaltate (LiCoO ₂ ) or lithium manganate (LiMn _{2 ).} O ₄ ), lithium nitric acid (LiNiO ₂ ), ternary lithium compound of Li, Co, Mn, Ni [Li(Co _x Mn _y Ni _z )O ₂ ], sulfur-based (TiS ₂ ), olivine (LiFePO _{4 )} Any one or more of LiMnPO ₄ ).

[49] The method for producing a positive electrode for a storage battery according to any one of the above-mentioned, wherein the positive electrode active material contains lithium cobaltate (LiCoO ₂ ) or lithium manganate. a ternary lithium compound (Li(Co _x Mn _y Ni _z )O ₂ ), a sulfur-based (TiS ₂ ), or an olivine system of (LiMn ₂ O ₄ ), lithium nickelate (LiNiO ₂ ), Co, Mn, and Ni Any one or more of (LiFePO ₄ and LiMnPO ₄ ).

[50] The battery according to [45] or [47], wherein the positive electrode active material contains lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium nickelate (LiNiO ₂ ), Co, Any one or more of a ternary lithium compound of Mn and Ni, such as Li(Co _x Mn _y Ni _z )O ₂ , a sulfur-based (TiS ₂ ), or an olivine-based (LiFePO ₄ or LiMnPO ₄ ).

[51] The battery according to the above [45] or [47] wherein the negative electrode active material contains graphite.

[52] The battery current collector according to any one of the above [1], wherein the compound is a compound which is crosslinked by a polysaccharide polymer.

The method for producing a current collector for a storage battery according to any one of the above aspects, wherein the compound is a compound which is crosslinked by a polysaccharide polymer.

[54] The battery according to the above [45] or [47] wherein the compound is a compound which is crosslinked by a polysaccharide polymer.

[55] The battery according to [54] above, wherein the compound is acrylamide, acrylonitrile, chitosan pyrrolidone carboxylate, hydroxypropyl chitosan, phthalic anhydride, maleic anhydride, Any of acid anhydrides such as trimellitic anhydride and pyromellitic anhydride to crosslink the polysaccharide polymer.

[56] The battery according to the above [45] or [47] wherein the lithium ion or fluoride ion of the compound has a conductivity of 1 × 10 ^-2 S/cm or more.

The battery current collector according to any one of the items 1 to 4, wherein the number average molecular weight of the compound is 50,000 or less.

[58] The battery according to the above [45] or [47], wherein The number average molecular weight of the compound is 50,000 or less.

[59] A mobile body and a power electric tool characterized by being as described in any one of the above [45], [47], [50], [51], [54] to [56], [58]. The battery is loaded.

The battery current collector, the positive electrode, the negative electrode, the battery, and the battery current collector, the positive electrode, the negative electrode, and the battery manufactured by the production method of the present invention greatly improve the initial capacity retention rate at a high current value. Therefore, it is suitable for use in batteries with excellent rapid charge and discharge characteristics.

[The best form for implementing the invention]

The invention is described in more detail below. Further, in the present specification, the term "aluminum" means aluminum and an aluminum alloy. Also, copper refers to the meaning of pure copper and copper alloy.

The aluminum foil which can be used in the present invention is not particularly limited, and various materials such as pure aluminum-based A1085 material or A3003 material can be used. Further, the thickness is preferably 5 to 100 μm. Further, the copper foil is also the same, and it is preferable to use a rolled copper foil or an electrolytic copper foil. In the present invention, an aluminum foil is used for the positive electrode side and a copper foil is used for the negative electrode side.

When the thickness of the aluminum foil and the copper foil is 5 μm or less, the strength is insufficient and the coating step of forming the collector layer may cause cracking of the foil; on the other hand, when it exceeds 100 μm, the proportion of the foil in a given volume of a battery increases. , resulting in a reduction in battery capacity, is very suitable.

The positive electrode active material used in the present invention is not particularly limited, and a substance capable of occluding lithium (ion) is preferably contained. Specifically, lithium cobalt oxide (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium nickelate (LiNiO ₂ ), and further, a ternary lithium compound of Co, Mn, and Ni [Li ( Co _x Mn _y Ni _z )O ₂ ], sulfur-based (TiS ₂ ), olivine-based (LiFePO ₄ , LiMnPO ₄ ), and the like are suitable.

Further, the positive electrode active material preferably has a particle diameter of 1 to 50 μm. When the particle diameter is 50 μm or more, the inclusion and desorption in the inside and outside of the particles cause unevenness, which is extremely unsuitable. On the other hand, when it is 1 μm or less, the crystallinity is lowered and the particle structure is disordered, and the performance deterioration is not suitable.

A known negative electrode active material used in the negative electrode can be used. A graphite system such as graphite, an amorphous graphite system, an oxide system or the like is not particularly limited.

The ion-permeable compound which can be used in the present invention, the compound which is not swollen with respect to the organic solvent, the compound which is not peeled off in the peeling test using the organic solvent, and the compound which does not peel off in the tape peeling test (hereinafter collectively referred to as film formation) Compounds) are listed below.

The ion permeable compound is preferably a material having an ion permeating property (including a compound), for example, a crosslinked polymer of cellulose and acrylamide, and a crosslinked polymerization of cellulose and chitosan pyrrolidone carboxylate. Things are more suitable. In addition to these, it is also possible to use a crosslinking agent to crosslink the chitosan or chitin of the polysaccharide polymer. Crosslinking agents which can be used include acrylamide, acrylonitrile, chitosan pyrrolidone carboxylate, hydroxypropyl chitosan, or phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Anhydride is more suitable.

From the viewpoint of battery performance, the larger the ionic conductivity is preferred. In particular, it is more preferable that the lithium ion has a large conductivity; and a compound having a lithium ion conductivity of 1 × 10 ^-2 S/cm or more is suitable. A compound having a conductivity of fluorine ion of 1 × 10 ^-2 S/cm or more is also suitable.

Further, among the above compounds which form a compound for a film, it is preferred to be resistant to an organic solvent and to a strong adhesion to a metal foil. The reason for this is that an organic electrolyte solution is usually used as an electrolytic solution in a lithium ion battery, and the formed film is dissolved in the electrolyte.

In general, compounds having organic solvent resistance include those known as polyamidamine and polyamidoximine, which are very expensive and are not suitable for practical use. Further, the average molecular weight of these is as small as 50,000, and the adhesion to the metal foil is insufficient. On the other hand, those having an average molecular weight of 50,000 or more include the above-mentioned PVDF, PTFE, etc., and the adhesion of the metal foil is sufficient, but these are swollen in an organic solvent, and the resistance to an organic solvent is extremely weak. Therefore, it is suitable for those having an average molecular weight of 50,000 or less, high adhesion to a metal foil, and high resistance to an organic solvent.

The measure for measuring these properties can be determined by a peeling test (slipping test) and a tape peeling test (JIS D0202-1988) with respect to the swelling property of the solvent, the cloth immersed in the solvent.

The material exhibiting the above characteristics may be one obtained by crosslinking a polysaccharide polymer with an acrylic additive or an acid anhydride, or a chitosan-based derivative.

The electron conductive carbon fine particles which can be used in the present invention are not particularly limited, and are preferably acetylene black, ketjen black, fumed carbon fiber, graphite or the like. In particular, the resistance of the powder is preferably 100% of the pressed powder of 1 × 10 ^-1 Ω ‧ cm or less. The above can be used in combination according to the needs.

The particle size of the above-mentioned electron conductive carbon fine particles is not particularly limited, and is preferably 10 to 100 nm. Further, the shape is not spherical, and the anisotropy is progressed in a needle shape or a rod shape. The reason is explained below. Electron-conductive carbon microparticles share the movement of electrons in a lithium secondary battery. At the time of charging, electrons supplied from the outside must pass through the aluminum foil to reach the positive electrode active material, so that the contact area between the aluminum foil and the positive electrode active material is preferably increased. Therefore, the larger the surface area of each mass, the more suitable the fine particles. And to ensure the battery capacity, it has to be achieved in a small amount as much as possible. Therefore, electron conductive carbon fine particles having an anisotropy in shape are suitable.

In the present invention, the film containing the film-forming compound and the carbon fine particles is not particularly limited, and a well-known method can be employed. Specifically, there are a casting method, a bar coating method, a dipping method, a printing method, and the like. Among these methods, a rod coating method, a casting method, and the like are suitable from the viewpoint of easy control of the film thickness. A film containing carbon fine particles can be formed as a current collector (for a positive electrode or a negative electrode) on the aluminum foil or the copper foil by the above method. Further, the thickness thereof is preferably 0.1 μm or more and 10 μm or less. When the thickness is 0.1 μm or less, the desired effect cannot be obtained. Not very suitable. On the other hand, when the thickness is 10 μm or more, the ratio of the active material in a volume determined by one battery is relatively lowered, which is not suitable.

On the other hand, when a film containing a positive electrode active material or a negative electrode active material is formed, it can be produced by the same method. Further, the film thickness is preferably 10 μm or more and 500 μm or less. When the film thickness is 10 μm or less, one The proportion of the active material in the volume of the battery is too small, which is extremely unsuitable for reducing the battery capacity. On the other hand, when it is 500 μm or more, it is not suitable because it falls off from the foil or the resistance inside the battery increases.

The case of forming a film containing a positive electrode active material will be described in more detail below. In the case where the negative electrode active material is contained, the aluminum foil may be replaced by a copper foil and the positive electrode active material may be replaced by a negative electrode active material in the following description.

The composition ratio of the film is adjusted at the stage of forming the paste of the film. Specifically, a compound for forming a film, a carbon compound, a positive electrode active material, or the like is mixed by a kneader or the like, and a solvent is added thereto to adjust the viscosity to prepare a film. Further, the solvent scatters in the subsequent step, and only the solid content (formation of the film compound, carbon fine particles, and positive electrode active material) remains in the film. The ratio of the positive electrode active material is preferably 1 to 30% by mass, the carbon fine particles are 1 to 30% by mass, and the positive electrode active material is 65% by mass or more.

Further, the thickness of the film is preferably 0.1 μm or more and 500 μm or less. When the thickness is 0.1 μm or less, the desired effect cannot be obtained. On the other hand, when it is 500 μm or more, there is a fear that the film is broken and peeled off from the aluminum foil, and it is not suitable.

The present invention can provide a current collector of a double layer film on the lower layer and the upper layer of the aluminum foil. In this case, a film containing a film for forming a film and carbon fine particles is used as a lower layer, and a film containing a binder, carbon particles, and a positive electrode active material is an upper layer. The binder contained in the upper layer may have an effect of fixing the particles, and a compound for forming a film may be used, and the polysaccharide polymer may be crosslinked by, for example, an acrylic additive, or may be used as it is. Polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE).

In the battery evaluation of the current collector for a storage battery of the present invention, the current collector can be made electrically electroded to constitute a storage battery having a well-known separator and an organic electrolytic solution.

Further, the performance can be evaluated by mounting the battery of the present invention on a moving body (vehicle such as an automobile or a bicycle) or a power electric tool (electric drilling machine or impact wrench).

1‧‧‧Aluminum foil

2‧‧ ‧ film

3‧‧‧ carbon particles

4‧‧‧Ion permeable compounds

5‧‧‧ positive active material

Fig. 1 is a schematic view showing a cross-sectional structure of a current collector in a lower layer in the first embodiment of the present invention.

Fig. 2 is a schematic view showing a cross-sectional structure of a positive electrode according to a second embodiment of the present invention.

[Examples]

The invention is specifically described below by way of examples and comparative examples. The invention is not limited to the embodiments described below.

[Example 1]

An aluminum foil having a thickness of 30 μm of A1085 material was prepared. Next, chitosan, which is a polysaccharide polymer having an ion-permeable compound, is prepared by crosslinking with pyromellitic anhydride. This molecular weight was determined to be 35,000 by GPC. It was mixed with carbon fine particles (acetylene black: particle diameter: 40 nm) having electron conductivity to prepare a paste. Using water as a solvent, the mass ratio of ion-permeable compound, carbon microparticles, and water is 35:15: 50. Next, a thin layer coater (void: 10 μm) was used to coat the paste on the aluminum foil by a casting method; thereafter, it was dried in air at 180 ° C for 3 minutes, and thermally hardened to obtain an ion-containing material. An aluminum foil of a film of a permeable compound and carbon microparticles.

As a result of measuring the thickness of the film after drying, the thickness was 5 μm, and the content of the electron-conductive carbon fine particles in the film was 30% by mass.

Next, a positive electrode paste made of a positive electrode active material, electron conductive carbon fine particles, a binder, and a solvent was used to form an electrode layer having a thickness of 200 μm as a positive electrode for a lithium ion secondary battery. In this case, the positive electrode active material is lithium cobaltate, acetylene black is used as conductive carbon fine particles, polyvinylidene fluoride (PVDF) is used as a binder, and N-methyl-2-pyrrolidone (NMP) is used as a solvent. The composition ratio of each component was: positive electrode active material: carbon fine particles: binder = 95:2:3 (mass ratio), and the solvent was 10% by mass of the mass of the positive electrode active material.

Further, a separator and a negative electrode formed on a copper foil are assembled, and an organic electrolyte solution is impregnated therein to obtain a lithium ion secondary battery.

The cycle characteristics of the lithium ion secondary battery obtained above were measured. The results are shown in Table 1. The measuring machine was a battery charging and discharging device HJ-2010 manufactured by Hokuto Electric Co., Ltd., and when the current rate was changed to 0.1 C, 2 C, and 20 C, the initial capacity retention rate after 100 cycles was expressed as a percentage. As is clear from Table 1, it is confirmed that the current rate is small, and the current collector of the present invention is used to confirm that the increase in the initial capacity retention rate is greatly improved on the high current rate side. That is, excellent rapid charge and discharge characteristics are exhibited.

Further, the internal resistance of the battery was measured. The measurement was carried out by an HIOKI 3551 battery tester using an AC-impedance method at a measurement frequency of 1 kHz. The measurement results are shown in Table 2. The smaller the measured value, the superior the rapid charge and discharge characteristics.

[Example 2]

An aluminum foil having a thickness of 30 μm of A1085 material was prepared. Next, a chitin which is a polysaccharide polymer which is an ion-permeable compound is prepared, and is crosslinked by maleic anhydride. This molecular weight was determined by GPC to be 30,000. A paste was prepared using the carbon microparticles (acetylene black: particle diameter: 40 nm) having electron conductivity, lithium manganate (LiMn ₂ O ₄ ) as a positive electrode active material, and a solvent (NMP). The composition ratio of the ion-permeable compound, the carbon fine particles, and the positive electrode active material in the paste was 2% by mass, 3% by mass, and 95% by mass, respectively, and the solvent was 10% by mass of the positive electrode active material. Next, in the same manner as in Example 1, the paste was applied onto an aluminum foil by using a thin coater (void: 250 μm); thereafter, it was dried in air at 180 ° C for 3 minutes to be thermally hardened. An aluminum foil having a film containing an ion-permeable compound, a carbon microparticle, and a positive electrode active material.

As a result of measuring the thickness of the film after drying, the thickness was 200 μm, and the content ratio of the electron conductive carbon microparticles to the positive electrode active material in the film was 3% by mass and 95% by mass, respectively.

Hereinafter, in the same manner as in the first embodiment, the separator and the negative electrode formed on the copper foil are assembled, and the organic electrolyte is impregnated therein to obtain lithium. Ion battery.

The initial capacity retention rate and internal resistance were measured in the same manner, and the results are shown in Tables 1 and 2, respectively.

[Example 3]

In Example 2, the material of the aluminum foil was changed from the material of A1085 to the material of A3003; the compound having ion permeability was replaced by chitosan of the polysaccharide polymer of the compound which was not peeled off in the peeling test using the organic solvent, The chitosan is crosslinked with acrylonitrile. The film formation of this compound was a thickness of 0.5 μm, and it was confirmed that the film was not peeled off as a result of a peeling test with ethanol in an organic solvent. Further, this molecular weight was measured by GPC to be 31,000. Further, carbon phase fine carbon fiber (trade name: VGCF, manufactured by Showa Denko Co., Ltd.) was used as the carbon fine particles. Further, the positive electrode active material was changed to an olivine system (LiFePO ₄ ). Further, the amount of the carbon fine particles added was changed, and the composition ratio of the compound, the carbon fine particles, and the positive electrode active material which were not peeled off in the peeling test using the organic solvent in the paste was 2% by mass, 1% by mass, and 97% by mass, respectively.

Except for this, a lithium ion secondary battery was obtained in the same manner as in Example 2. The initial capacity retention rate and internal resistance were measured in the same manner, and the results are shown in Table 1.

[Example 4]

Preparation of the ion-permeable compound of Example 1 to make a polysaccharide polymer as a compound having no swelling property relative to NMP Chitosan, which is replaced by trimellitic anhydride, and NMP as a solvent. This molecular weight was determined to be 22,000 by GPC.

A lithium ion secondary battery was obtained in the same manner as in Example 1 except that it was used. The initial capacity retention rate and internal resistance were measured in the same manner, and the results are shown in Tables 1 and 2, respectively.

[Example 5]

A copper foil having a thickness of 9 μm of an electrolytic copper foil was prepared. Next, the cellulose of the polysaccharide polymer which is an ion-permeable compound is prepared to be crosslinked by chitosan pyrrolidone carboxylate. This molecular weight was determined by GPC to be 40,000. It was mixed with carbon fine particles (acetylene black: particle diameter: 40 nm) having electron conductivity to prepare a paste. Using NMP as a solvent, the mass ratio of the ion-permeable compound to the carbon microparticles and the solvent was 35:15:50. Next, a paste is applied on the copper foil by gravure printing using a gravure printing cylinder (#200); thereafter, it is dried in air at 180 ° C for 3 minutes, and is thermally hardened to obtain an ion-containing ion. A copper foil (current collector) of a film of a permeable compound and carbon microparticles.

As a result of measuring the thickness of the film after drying, the thickness was 0.2 μm, and the content of the electron-conductive carbon fine particles in the film was 30% by mass.

Next, a negative electrode paste made of a negative electrode active material, electron conductive carbon fine particles, a binder, and a solvent was used to form an electrode layer having a thickness of 250 μm as a negative electrode for a lithium ion secondary battery. At this time, the negative electrode active material is graphite, acetylene black is used as conductive carbon particles, and polyvinylidene fluoride is used. (PVDF) is a binder and N-methyl-2-pyrrolidone (NMP) is a solvent. The composition ratio of each component is: negative electrode active material: carbon fine particles: binder = 92:5:3 (mass ratio), and the solvent is 10% by mass of the mass of the negative electrode active material.

Hereinafter, the separator and the positive electrode formed on the aluminum foil used in Example 1 were assembled in the same manner as in Example 1, and the organic electrolyte solution was impregnated thereinto to obtain a lithium ion secondary battery. The initial capacity retention rate and internal resistance were measured in the same manner, and the results are shown in Tables 1 and 2, respectively.

[Example 6]

The ion-permeable compound of Example 5 was prepared so that the chitosan of the polysaccharide polymer which does not peel off in the tape peeling test was replaced with acrylonitrile. This compound was formed into a film having a thickness of 0.5 μm, and the result of the tape peeling test was 100/100, and it was confirmed that it was not peeled off. Further, this molecular weight was determined to be 26,000 by GPC. Further, carbon phase fine carbon fiber (trade name: VGCF, manufactured by Showa Denko Co., Ltd.) was used as the carbon fine particles. Otherwise, in the same manner as in Example 5, a lithium ion secondary battery was obtained. The initial capacity retention rate and internal resistance were measured in the same manner, and the results are shown in Tables 1 and 2, respectively.

[Comparative Example 1]

In the material of the A1085 of the first embodiment, a composite film formed of the ion-permeable compound and the electron-conducting carbon microparticles is not formed; and the positive electrode active material (lithium cobaltate) represented by the embodiment 1 is formed. Electricity The collector layer formed of the sub-conductive carbon microparticles (acetylene black), the binder (PVDF), and the solvent (NMP) was 200 μm, thereby obtaining a positive electrode current collector. In the same manner as in Example 1, the initial capacity retention ratio and internal resistance were measured in the same manner as in Example 1, and the results are shown in Tables 1 and 2, respectively.

[Comparative Example 2]

A lithium ion secondary battery was fabricated in the same manner as in Example 1 except that the PVDF adhesive (the compound which was not peeled off in the peeling test using an organic solvent) was used instead of the ion-permeable compound of Example 5. In the same manner as in Example 1, the initial capacity retention ratio and the internal resistance were measured, and the results are shown in Tables 1 and 2, respectively. Although it can be processed to a battery, when the current collector having the film containing carbon fine particles is rubbed, the surface of the current collector is rubbed by the cloth immersed in NMP, and large peeling occurs. Even if the initial characteristics are good, it is a battery that is not resistant to long-term use.

[Comparative Example 3]

A lithium ion secondary battery was fabricated in the same manner as in Example 1 except that a PVA (polyvinyl alcohol) adhesive (a compound which was not peeled off in the tape peeling test) was used instead of the ion-permeable compound of Example 1. In the same manner as in Example 1, the initial capacity retention ratio and the internal resistance were measured, and the results are shown in Tables 1 and 2, respectively. Although the battery can be processed, the surface of the current collector is largely peeled off as a result of performing a tape peeling test at the stage of providing the current collector containing the film of carbon fine particles. Even if the initial characteristics are good, it is a battery that is not resistant to long-term use.

As is clear from Table 1, the initial capacity retention ratio of the comparative example at the low current rate was not inferior to that of the embodiment of the present invention, but at the high current rate, the initial capacity retention ratio was largely lowered. That is, it is difficult to perform rapid charge and discharge.

Further, as is clear from Table 2, the internal resistance is small and can be used as a battery for rapid charge and discharge.

The rapid charge and discharge characteristics of the present invention are superior, and it is presumed that the ion-permeable adhesive and the electron-conductive carbon microparticles share the movement of the ions and the movement of the battery, and the film containing the metal foil and the carbon microparticles is densely bonded to the electrode film. For the sake of it.

The terms and expressions used herein are intended to be illustrative and not intended to be interpreted by the user. The features described and illustrated herein are not to be construed as limiting the scope of the invention.

[industrial use]

The present invention provides a battery current collector, a battery current collector manufacturing method, and a battery including the current collector. In particular, the battery current collector including the aluminum foil including the ion-permeable compound and the carbon fine particles, and the related invention can extremely improve the initial capacity retention rate at a high current rate when the battery is constructed. It is suitable for use in communication equipment for loading batteries or digital home appliances because of its superior performance and rapid charge and discharge characteristics. By virtue of this characteristic, the use of a machine for loading a battery can be expanded, and the range of utilization of industries other than the expected one can be expanded.

Claims (16)

A current collector for a battery, comprising: an aluminum foil or a copper foil provided with a film, the film having a crosslinked polymer selected from the group consisting of cellulose and acrylamide, and a cellulose and chitosan pyrrolidone carboxylate A co-polymer, a chitosan cross-linking agent by a crosslinking agent, and a compound of one or more types in which a chitin is cross-linked by a crosslinking agent, and carbon fine particles. The battery current collector according to claim 1, wherein the compound is one or more compounds selected from the group consisting of a chitosan crosslinker by a crosslinking agent and a chitin crosslinker by a crosslinking agent. The crosslinking agent is one or more selected from the group consisting of acrylamide, acrylonitrile, chitosan pyrrolidone carboxylate, hydroxypropyl chitosan, and an acid anhydride. The battery current collector according to claim 2, wherein the acid anhydride is one or more selected from the group consisting of phthalic anhydride, maleic anhydride, trimellitic anhydride, and pyromellitic anhydride. The current collector for a battery according to claim 1, wherein the number average molecular weight of the compound is 50,000 or less. The battery current collector according to claim 1, wherein the thickness of the film is 0.1 μm or more and 10 μm or less. The current collector for a battery according to claim 1, wherein the carbon microparticles are acetylene black, ketjen black, fumed carbon fiber, and graphite. A positive electrode for a storage battery comprising an aluminum foil having a film containing a compound and carbon fine particles in a lower layer, and a film containing a binder, carbon particles, and a positive electrode active material in the upper layer; The compound is selected from the group consisting of a crosslinked polymer of cellulose and acrylamide, a crosslinked polymer of cellulose and chitosan pyrrolidone carboxylate, a crosslinker of chitosan with a crosslinking agent, and a crosslinking agent. One or more of the groups of chitin crosslinkers. A negative electrode for a storage battery comprising a copper foil which is provided with a film containing a compound and carbon fine particles in a lower layer, and a film containing a binder, carbon fine particles and a negative electrode active material in an upper layer; Cross-linked polymer of free cellulose and acrylamide, cross-linked polymer of cellulose and chitosan pyrrolidone carboxylate, cross-linking chitosan with cross-linking agent and cross-linking chitin with cross-linking agent One or more of the groups. A method for producing a battery, which is a method for producing a battery in which an organic electrolytic solution is impregnated into a laminate in which a positive electrode, a separator, and a negative electrode are stacked in this order, and is characterized in that a positive electrode is used as the positive electrode of claim 7. A method for producing a battery, which is a method for producing a battery in which an organic electrolytic solution is impregnated into a laminate in which a positive electrode, a separator, and a negative electrode are stacked in this order, and is characterized in that a negative electrode is used as the negative electrode of claim 8. A storage battery is a battery in which an organic electrolyte is impregnated in a laminate in which a positive electrode, a separator, and a negative electrode are stacked in this order, and is characterized in that a positive electrode is used as the positive electrode of claim 7. A storage battery is a battery in which an organic electrolyte is impregnated in a laminate in which a positive electrode, a separator, and a negative electrode are stacked in this order, and a negative electrode is used as the positive electrode of claim 8. A slurry for producing a current collector for a battery, comprising a compound, carbon microparticles and a solvent; the compound is selected from the group consisting of a crosslinked polymer of cellulose and acrylamide, cellulose and chitosan pyrrolidone carboxylate A cross-linked polymer of an acid salt, a compound obtained by crosslinking a chitosan with a crosslinking agent, and a compound of a group of a chitin cross-linking by a crosslinking agent. A method for producing a current collector for a battery, characterized in that a compound and a carbon are formed on an aluminum foil or a copper foil by a method selected from the group consisting of a casting method, a rod coating method, a dipping method, and a printing method. a film of microparticles; the compound is selected from the group consisting of a crosslinked polymer of cellulose and acrylamide, a crosslinked polymer of cellulose and chitosan pyrrolidone carboxylate, a crosslinker of chitosan with a crosslinking agent, and The cross-linking agent allows one or more compounds of the chitin cross-linking group to be grouped. A method for producing a positive electrode for a storage battery, characterized in that a film comprising a binder, carbon fine particles and a positive electrode active material is formed on a battery current collector comprising an aluminum foil having a film; the compound is selected from the group consisting of cellulose and propylene a crosslinked polymer of guanamine, a crosslinked polymer of cellulose and chitosan pyrrolidone carboxylate, a chitosan crosslinker by a crosslinking agent, and a chitin crosslinker by a crosslinking agent More than one compound. A method for producing a negative electrode for a storage battery, characterized in that a film comprising a binder, carbon fine particles and a negative electrode active material is formed on a battery current collector comprising a copper foil having a film; the compound is selected from the group consisting of cellulose and a crosslinked polymer of acrylamide, a crosslinked polymer of cellulose and chitosan pyrrolidone carboxylate, a crosslinker of chitosan with a crosslinking agent, and a group of chitin crosslinkers by a crosslinking agent More than one compound.