JP4580139B2 - Battery current collector and battery using the same - Google Patents

Description

【００９４】
この表１の電池理論容量の結果から明らかなように、本発明の表面多孔メッキ繊維を含む集電材は高容量化が可能で、しかも集電性能に優れるものであった。
また、４．０Ｃ利用率の結果から明らかなように、本発明の集電材はハイレート放電での集電性能に優れるものであった。
【００９５】
【発明の効果】
本発明の集電材は集電性に優れている。また、高容量の電池を製造できるものである。
【００９６】
本発明の電池は集電性能に優れ、高容量の電池であることができる。
【図面の簡単な説明】
【図１】（ａ） 本発明の表面多孔メッキ繊維の断面映像模式図
（ｂ） 本発明の別の表面多孔メッキ繊維の断面映像模式図
（ｃ） 本発明の表面多孔メッキ繊維の繊維軸方向における断面映像模式図
（ｄ） 本発明の別の表面多孔メッキ繊維の繊維軸方向における断面映像模式図
【図２】本発明のアルカリ二次電池の一部を切り欠いた斜視図
【図３】集電体が渦巻き円状に巻回された図２のＡ−Ａ線断面図
【図４】集電体が渦巻き角状に巻回された図３に対応する断面図
【図５】集電体が蛇腹状に屈曲積層された図３に対応する断面図
【符号の説明】
１０ 表面多孔メッキ繊維
１１ 細孔
１２ 繊維表面
１３ 開孔部
１０１ 電池
１０２ 正極
１０２ａ ニッケル片
１０３ 負極
１０４ セパレータ
１０４ａ 第１セパレータ
１０４ｂ 第２セパレータ
１０６ 発電体
１０７ 電池ケース
１０７ａ 缶底
１０７ｂ くびれ部
１０８ 封入板
１０８ａ 突起
１０９ａ ロア絶縁体
１０９ｂ アッパ絶縁体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery current collector and a battery using the same.
[0002]
[Prior art]
Conventionally, batteries, particularly alkaline secondary batteries, are highly reliable and can be reduced in size and weight, and thus are frequently used as power sources for various devices ranging from portable devices to large industrial facilities. In most of the alkaline secondary batteries, a nickel hydroxide electrode is used as a positive electrode. The nickel hydroxide electrode has a structure in which a positive electrode active material for causing a battery reaction is supported on a current collector that shares a current collecting function. As the current collector in that case, a sintered nickel plate or a punched nickel plate obtained by sintering nickel powder has been widely used. The capacity of the battery is determined by the amount of the active material to be filled in the voids of the nickel plate, and the filling amount of the active material is determined by the porosity of the nickel plate, so that the porosity of the nickel plate is made as large as possible. It is desirable.
[0003]
However, the sintered nickel plate uses a punched nickel plate as a base material, and this base material has a low porosity of 75 to 80% and has a low nickel content in the nitrate solution. It was necessary to repeat the impregnation and neutralization filling cycles several times or more, and as the filling cycle was repeated, the penetration of the nitrate solution into the nickel plate deteriorated, making it difficult to fill the active material with high density. . Therefore, recently, in response to demands for battery downsizing and higher capacity, a three-dimensional network structure that has a large porosity and can increase the packing density of the active material in order to increase the packing density of the active material of the current collector. A current collector made of body is used.
[0004]
As the current collector of this three-dimensional network structure, for example, “a nickel-plated non-woven electrode made of fibers and subjected to water-entanglement treatment on the web and then electroless nickel-plated” has been proposed (Japanese Patent Laid-Open No. 5-290838). ).
[0005]
[Patent Document 1]
JP-A-5-290838
[0006]
[Problems to be solved by the invention]
However, since the nickel-plated nonwoven fabric electrode disclosed in the above publication has poor current collecting properties, the utilization factor of the active material is low and high-rate discharge cannot be performed. In particular, when the thickness is increased in order to increase the capacity, the current collecting property is poor.
[0007]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a battery current collector and a battery excellent in current collection, and particularly a battery current collector and battery having a high capacity and excellent current collection. And
[0008]
The invention according to claim 1It is a current collector for a battery made of a plated non-woven fabric composed of only a plated fiber having a plating layer on the surface of a fiber mainly comprising a thermoplastic resin, and the surface of the fiber is 10,000 μm as the plated fiber. ² The surface perforated plating fiber having 10 to 55000 pores per hole, the surface perforated plating fiber is only on the surface, and the shape of the opening portion of the pore is substantially circular or substantially polygonal, A battery current collector, wherein pores having an average diameter of an aperture of 0.5 to 15 μm and an average depth of 0.1 to 15 μm are formed.Is. As described above, the surface porous plating fiber having pores formed only on the surface and having a plating layer on the surface has not only a large surface area but also excellent adhesion to the active material. Battery current collectors containing fibers (hereinafter sometimes simply referred to as “current collectors”) are excellent in current collection.Moreover, since the pores have such a shape, size, and depth, the adhesion between the active material and the surface porous plating fiber is particularly excellent. As a result, the current collection is excellent and the capacity is high. The battery is easier to manufacture. Furthermore, since many pores are present, the number of contact points between the active material and the surface porous plating fiber also increases, so that it is easy to manufacture a battery with excellent current collection and high capacity.Thus, since the surface porous plating fiber is excellent in current collecting property, the amount of fibers constituting the current collecting material can be reduced, the porosity of the current collecting material can be increased, and as a result, the filling amount of the active material can be reduced. Since it can be increased, a high-capacity battery can be manufactured. In addition, the conventional fiber having voids on the surface as disclosed in JP-A-5-290838 does not have pores formed only on the surface, but also has pores formed inside, Although the surface area is large, the adhesiveness to the active material fibers is low, and therefore sufficient current collecting performance cannot be obtained.
[0012]
Claim2According to the invention, “the total surface area of the fibers per unit volume of the plated nonwoven fabric is 500 cm.²/ Cm³It is the above,Claim 1Current collector for batteries. Is. As described above, since the total fiber surface area is large, the number of contact points between the active material and the surface porous plating fiber is increased. Therefore, it is easy to manufacture a battery having excellent current collecting property and high capacity.
[0013]
Claim3The invention related to "Claim 1 or claim 2A battery using the battery current collector described above. Is. Thus, since it is a battery using the said current collection material, it can be excellent in current collection performance and can be a high capacity | capacitance battery.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The current collector of the present invention has pores formed only on the surface and includes a surface porous plating fiber having a plating layer on the surface, and not only has a large surface area, but also has excellent adhesion to the active material. Therefore, the current collecting property is excellent. Moreover, since the surface porous plating fiber is excellent in current collecting property, the amount of fibers constituting the current collecting material can be reduced, the porosity of the current collecting material can be increased, and as a result, the filling amount of the active material is increased. Therefore, a high capacity battery can be manufactured.
[0015]
Such a current collector of the present invention can be produced, for example, as follows.
[0016]
First, a non-porous fiber is prepared. This non-porous fiber is a fiber having at least a surface mainly composed of a thermoplastic resin and having no pores on the fiber surface, and heating (for example, heating at a temperature of 50 ° C. or higher, preferably heating at a temperature of 80 ° C. or higher) It is sufficient if the fiber is provided with a thermoplastic resin that melts by the following method.
[0017]
Such non-porous fibers can be obtained, for example, by synthetic fibers obtained by a melt spinning method, which is a conventional fiber manufacturing method, by a spunbond method, a melt blow method, or a flash spinning method, which is a conventional nonwoven fabric manufacturing method. Examples thereof include fibers or fibers in which the core portion is made of natural fibers or inorganic fibers and the sheath portion is made of a thermoplastic resin.
[0018]
Examples of the synthetic fiber include a synthetic fiber made of a thermoplastic resin (for example, a polyolefin fiber, a polyester fiber, or a polyamide fiber). The synthetic fiber is made of one kind of thermoplastic resin. Or a composite fiber in which two or more different thermoplastic resins are combined or mixed. Examples of the latter composite fiber include composite fibers in which two or more types of thermoplastic resins having different melting points are combined. Examples thereof include copolymer polyester / polyester, copolymer polypropylene / polypropylene, polypropylene / polyamide, and polyethylene / polypropylene. And composite fibers made of a combination of resins such as polypropylene / polyester or polyethylene / polyester. If the core-sheath type composite fiber has a high melting point resin in the core and a low melting point resin in the sheath, the surface porous fiber (including the surface porous plating fiber plating layer is provided without causing fiber shrinkage or thread breakage). Fiber, the same applies hereinafter), which is preferable.
[0019]
In addition, the non-porous fiber is preferably composed of only a fiber-forming thermoplastic resin as a whole, but a fiber whose core portion does not have a melting point and has a decomposition temperature, such as rayon fiber, acetate fiber, A fiber made of a fiber such as wool fiber or carbon fiber, and a sheath part made of a thermoplastic resin can also be used. In addition, the non-porous fiber may be a fiber whose core portion is made of an inorganic fiber such as glass fiber, ceramic fiber, or metal fiber, and whose sheath portion is made of a thermoplastic resin. The sheath component of these fibers can be obtained, for example, by coating.
[0020]
The non-porous fiber “at least the surface is mainly composed of a thermoplastic resin” has an area occupied on the fiber surface of the thermoplastic resin of 50% or more (preferably 60% or more, more preferably 70% or more, particularly, Preferably 90% or more, most preferably 100%).
[0021]
The cross-sectional shape of the non-porous fiber does not need to be circular, and may be non-circular (for example, a polygon such as a triangle, an ellipse, an ellipse, an alphabet such as a T shape, etc.).
Moreover, you may be in the state divided | segmented into the fibril form by external force.
[0022]
The average diameter and length of the non-porous fibers are not particularly limited, but the average diameter of the fibers is preferably 1 μm or more, and more preferably 30 μm to 55 μm. Here, the “average diameter” of the fiber is the diameter of a circle having the same area as the cross-sectional area of the fiber when the cross-sectional shape of the fiber is other than a circle, and the number average by sampling from any 500 or more positions of the fiber The fiber diameter. In the case of commercially available fibers, if the number average fiber diameter is specified in the catalog or specification, the value may be used as the average diameter of the fiber, or the fineness is specified in the catalog or specification. In this case, a value converted from the fineness may be used as the average diameter.
[0023]
Next, solid particles are fixed to the surface of the non-porous fiber as described above to form solid particle fixed fibers.
[0024]
The solid particles are either inorganic or organic as long as they have a melting point or decomposition temperature higher than the melting point of the thermoplastic resin constituting the surface of the non-porous fibers and can be removed after fixing. There can also be. Examples of such solid particles include solid particles that dissolve in a solvent (for example, water, aqueous solution, acid, alkaline aqueous solution, etc.) that does not substantially dissolve the thermoplastic resin that forms the surface of the non-porous fiber. For example, there are water-soluble inorganic materials, metal salts, water-soluble resins, metals, and the like. Such solid particles can be extracted and removed using the solvent. In addition to extraction and removal, solid particles that can be removed by vibration, ultrasonic cleaning, fiber shrinkage, fiber surface peelability improving processing, or the like may be used. More specifically, sodium chloride, calcium chloride, calcium carbonate, other various metal salts, water-soluble resins, metal particles, ceramics, zeolite, and other various inorganic materials can be exemplified.
[0025]
The melting point or decomposition temperature of the solid particles is such that the surface of the nonporous fiber is melted or deformed by the heat of the heated solid particles so that the solid particles are fixed to the fiber surface. Among the thermoplastic resins to be used, it is necessary to be higher than the melting point of the resin having the lowest melting point.
[0026]
The average particle size of the solid particles is not particularly limited, but the average particle size of the solid particles is preferably 0.1 to 20 μm so that pores excellent in adhesion with the active material can be formed. More preferably, it is 5-15 micrometers. The average particle diameter of the solid particles refers to the number average particle diameter of the solid particles. The “number average particle size” is obtained by enlarging and photographing solid particles with a scanning electron microscope or the like, measuring the particle size of any 500 or more solid particles, and dividing by the measured number. Value. At this time, if the solid particles are not spherical, the diameter of the circumscribed circle of each solid particle that can be confirmed in the captured image of the solid particle is set as the particle diameter of each particle. In the case of commercially available solid particles, when the number average particle diameter is clearly shown in catalogs or specifications, the value may be used as the average particle diameter of the solid particles.
[0027]
Solid particles are fixed to the surface of the non-porous fiber to form solid particle-fixed fibers. As a method for fixing the solid particles, for example, the solid particles as described above are used to form the surface of the non-porous fiber. The surface of the non-porous fiber is brought into contact with the non-porous fiber by contacting the solid particle heated at a temperature within the range of maintaining the shape as a solid, up to the melting point of the thermoplastic resin or lower than the melting point of the solid particle or the decomposition temperature. There is a method of fixing by fusing or deformation. Also, a method of fixing the surface of the non-porous fiber by fusing or deformation by bringing the solid particles into contact with the surface of the non-porous fiber heated to a temperature higher than the melting point of the thermoplastic resin. But it ’s okay. The former method is more preferable because solid particles are not buried and pores can be reliably formed.
[0028]
The method of contacting the solid particles with the non-porous fibers is not particularly limited as long as the solid particles can be fixed to the non-porous fibers. For example, (1) containing heated solid particles A method of spraying an air flow on non-porous fibers, (2) a method of allowing heated solid particles to spontaneously fall on non-porous fibers, and (3) shaking a container charged with heated solid particles and non-porous fibers. (4) a method of immersing non-porous fibers in heated solid particles, or (5) a method of exposing non-porous fibers to a fluidized bed of heated solid particles.
[0029]
The solid porous particles can be obtained by removing the solid particles of the solid-particle-fixed fibers thus formed.
[0030]
The method for removing the solid particles of the solid particle-fixed fiber is not particularly limited as long as the solid particles of the solid particle-fixed fiber can be removed. For example, the thermoplastic resin constituting the surface of the non-porous fiber is substantially removed. There is a method in which solid particles dissolved in a solvent that does not dissolve are removed using the solvent. For example, the solid particles can be removed using a water-soluble inorganic substance, metal salt, water-soluble resin, metal, or the like as the solid particles, and water, an aqueous solution, an acid, an alkaline aqueous solution, or the like as the solvent. In particular, a method of using a metal salt or a water-soluble resin as the solid particles and removing it with water is preferable because the production cost is low. Examples of such metal salts include sodium chloride, calcium chloride, ammonium chloride, sodium bicarbonate, potassium bicarbonate, and the like. Examples of such water-soluble resins include polyvinyl alcohol, polyethylene glycol, and polyacrylic acid.
[0031]
Other methods for removing the solid particles of the solid particle fixed fiber include, for example, a method in which the solid particle fixed fiber is vibrated to separate the solid particle, a method in which the solid particle fixed fiber is separated by ultrasonic cleaning, or a solid The method of extending | stretching or shrink | contracting the fiber of particle | grain fixed fiber and peeling a solid particle etc. can be mentioned.
[0032]
When the surface porous fiber is produced by such a production method, pores can be formed only on the fiber surface while maintaining various physical properties such as fiber strength inherent to the nonporous fiber. In addition, since pores can be formed according to the shape and size of the solid particles, by using a solid particle corresponding to the shape and size of the active material used for the electrode, adhesion to the active material can be improved. Excellent surface porous fibers can be produced.
[0033]
Next, a nonwoven fabric is formed using the surface porous fibers thus obtained. In addition to the surface porous fiber, the nonwoven fabric may be formed by using not only the surface porous fiber but also a fiber having pores other than the surface or a non-porous fiber having no pores at all.
[0034]
As a method for producing this nonwoven fabric, first, a fiber web is formed by a dry method such as a card method or an air lay method, or a wet method. In particular, since the fiber web obtained by the wet method has small variations in basis weight and thickness, a uniform current collector can be obtained. As a result, an electrode having a uniform thickness can be formed by using this current collector, and an electrode group having excellent adhesion can be formed by winding the electrode, so that a battery having excellent charge / discharge characteristics can be obtained. Can do.
[0035]
Next, the fiber web may be used as a nonwoven fabric as it is, but it is preferable to perform a entanglement treatment or a heat treatment to enhance the strength characteristics to obtain a nonwoven fabric. As the entanglement process, for example, water entanglement process or entanglement process by needle punch can be employed. When the entanglement treatment is performed, the fibers are entangled with each other, the number of contact points between the fibers is increased, the strength characteristics are improved, and the porosity can be adjusted to an appropriate value.
[0036]
The heat treatment can fuse the contact points of the fiber web constituent fibers with each other to improve the overall strength characteristics. The temperature of the heat treatment needs to be adjusted as appropriate so as not to block the pores of the surface porous fiber. This heat treatment temperature can be appropriately determined experimentally.
[0037]
Although only one of the entanglement treatment and the heat treatment may be performed, it is preferable to perform the heat treatment after the entanglement treatment because the strength characteristics of the obtained nonwoven fabric can be remarkably improved.
[0038]
Next, the non-woven fabric may be plated to form a plated non-woven fabric containing surface porous plated fibers, that is, a current collector. It is preferable to improve the electrical conductivity and the adhesion between the metal plating formed on the fiber surface by improving the permeability and firmly bonding with metal ions.
[0039]
Examples of such hydrophilic treatment include sulfonation treatment, fluorine gas treatment, vinyl monomer graft polymerization, surfactant treatment, or hydrophilic resin application treatment. In particular, sulfonation treatment, fluorine gas treatment, or vinyl monomer grafting treatment is preferable because the plating film hardly falls off for a long period of time and the surface resistance is hardly raised.
[0040]
More specifically, the sulfonation treatment can be performed by immersing the nonwoven fabric in a solution such as fuming sulfuric acid, sulfuric acid, sulfur trioxide, chlorosulfuric acid, or sulfuryl chloride. Among these, the sulfonation treatment with fuming sulfuric acid is preferable because of its high reactivity and relatively easy sulfonation.
[0041]
In the fluorine gas treatment, for example, a mixture of fluorine gas diluted with an inert gas (for example, nitrogen gas, argon gas, etc.) and at least one gas selected from oxygen gas, carbon dioxide gas, sulfur dioxide gas and the like is used. It can be carried out by bringing the gas into contact with the nonwoven fabric. In addition, after making sulfur dioxide gas adhere beforehand to a nonwoven fabric, the method of making it contact with fluorine gas is an efficient and permanent hydrophilic treatment method.
[0042]
In the grafting process of vinyl monomer, for example, at least one type of graft polymerization solution selected from acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, vinyl pyridine, or styrene is impregnated into the nonwoven fabric and irradiated with ultraviolet rays. Processing can be mentioned. Among these, acrylic acid is suitable because it does not drop the plating film or increase the surface resistance for a long time.
Next, the non-woven fabric or the non-woven fabric subjected to the hydrophilization treatment is subjected to a plating treatment, and a plated layer is formed on the surface of the surface porous fiber to form the surface porous plated fiber. it can.
[0043]
This plating method is not particularly limited, but nickel plating is preferably performed by an electroless plating method. If necessary, it is preferable to further form an electrolytic plating film on the electroless plating film formed by the electroless plating method by an electrolytic plating method.
[0044]
More specifically, the “electroless plating method” includes a catalyst imparting step and an electroless plating step. The catalyst-imparting step includes a method of treating with a hydrochloric acid aqueous solution of stannous chloride and then catalyzing with an aqueous hydrochloric acid solution of palladium chloride, and a method of immobilizing only with a hydrochloric acid solution of barium chloride containing an amino group of a curing agent. However, the former method is preferable because the uniformity of the plating film thickness is excellent.
[0045]
The electroless plating process is a method of reducing nickel with a reducing agent in an aqueous solution generally containing nickel salts such as nickel nitrate, nickel chloride, nickel sulfate, etc., if necessary, complexing agent, pH adjusting agent, Buffers, stabilizers, etc. are added. In order to obtain a nickel film having particularly high purity, it is preferable to use hydrazine derivatives such as hydrated hydrazine, hydrazine sulfate, and hydrazine oxide as a reducing agent.
[0046]
The “electrolytic plating method” is performed using a plating bath. As the plating bath, a watt bath, a chloride bath, or a sulfamic acid bath can be used. In these baths, additives such as pH buffering agents and interfacial buffering agents may be used. After the electroless plated non-woven fabric is connected to the cathode and the nickel counter electrode is connected to the anode, a direct current or intermittent pulse current is applied to form a further electroplated layer on the electroless plated layer. be able to.
[0047]
For example, the surface porous plating fiber of the present invention produced in this way has pores formed only on the surface, and a plating layer is formed on the surface. The surface porous plated fiber of the present invention will be described with reference to FIGS. 1A and 1B which are schematic cross-sectional images of the surface porous plated fiber. Is formed. Here, “only the surface of the fiber” means that only the pores that are substantially visible from the surface (for example, the image of the surface of the fiber taken with a scanning electron microscope) are formed on the surface of the surface porous plating fiber. Means that As is apparent from FIGS. 1 (a) and 1 (b), when the pores are observed from the fiber surface side, the deepest portion of the pores in the fiber thickness direction is the pore opening. It can be confirmed from the department. From another viewpoint, the pores are shaped such that the fiber surface is depressed or a part of the fiber surface is hollowed out. For example, if a particulate layer is extracted and removed from a fiber that has been spun by mixing a fiber-forming thermoplastic resin with a particulate material that can be extracted with a certain solvent, and a plated layer is formed, the surface of the fiber will be open. However, since the deepest part in the fiber thickness direction of the pores cannot be observed from the fiber surface, it does not correspond to the surface porous plating fiber of the present invention. Although such a fiber has a large surface area, it has insufficient adhesion to the active material, and it is difficult to obtain sufficient current collecting performance.
[0048]
As long as the shape of the pores of the surface porous plating fiber of the present invention does not deviate from the concept of pores (as deviating from the concept of pores, for example, streaks, lines, strips, mountains, grooves, or The shape is not particularly limited, and is preferably a semi-spherical shape. The “semi-spherical sphere” includes a shape that is a substantially semi-spherical, a substantially semi-elliptical sphere, or a semi-polyhedron, and has a surface that forms a substantially semi-spherical, a substantially semi-elliptical sphere, or a semi-polyhedron. Including shape. Further, 10% to 90%, preferably 30% to 70% of the volume of the solid particles used in the production method as described above is detached from the surface of the nonporous fibers. It also includes the shape of a depression or pore as formed when
[0049]
It is preferable that the shape of the opening part in the fiber surface of the pore of the surface porous plating fiber of this invention is a substantially circular shape or a substantially polygonal shape. This is because, when the pores have such a shape, the adhesiveness to the active material is excellent, and as a result, the current collecting property is excellent and it is easier to manufacture a high-capacity battery. Here, as shown in FIGS. 1 (a) and 1 (b), the opening portion 13 refers to a contour formed by opening the pores 11 formed on the surface 12 of the surface porous plating fiber.
[0050]
Moreover, it is preferable that the average diameter of the said opening part is 0.5-15 micrometers, It is more preferable that it is 1-15 micrometers, It is more preferable that it is 5-15 micrometers. This is because when the average diameter of the aperture is 0.5 to 15 μm, the adhesion with the active material is further enhanced. Here, the “average diameter of the aperture” means that the diameter of the circumscribed circle of the aperture that can be confirmed by magnifying and photographing the side surface of the fiber with a scanning electron microscope or the like The number average aperture diameter by sampling from 500 or more arbitrary positions is said.
[0051]
Further, the long diameter of the aperture is preferably 5 times or less of the short diameter, more preferably 3 times or less, and more preferably 2 times or less so that the adhesion of the active material is excellent. Further preferred. The “long diameter of the aperture” means the longest straight line among the straight lines connecting any two points on the outline of the aperture in the pores appearing on the image of the fiber side surface by a scanning electron microscope or the like. The length refers to the length of the longest straight line of any straight line connecting two points where the straight line orthogonal to the long diameter of the open part and the outline of the open part intersect. Point to. In addition, when there are three or more points where the outline of the aperture intersects with respect to one straight line perpendicular to the major axis of the aperture, the straight line connecting any two of these points The longest straight line is defined as a straight line connecting the two points. Further, the comparison value between the major axis and the minor axis of the aperture is a number average comparison value obtained by sampling from arbitrary 500 or more pores.
[0052]
The depth of the pores is not particularly limited as long as the pores are formed only on the surface of the fiber, but the average depth of the pores is excellent so that the adhesion with the active material is excellent. Is preferably 0.1 to 15 μm, more preferably 3 to 10 μm, and still more preferably 5 to 10 μm. Here, the “average depth of the pores” is the depth of the deepest part of each pore that can be confirmed by observing the image of the surface porous plating fiber by magnifying a cross section of the surface porous plating fiber with a laser microscope or the like. About the thickness, it means the number average pore depth by sampling from arbitrary 500 or more pores of the fiber cross section. Here, the “depth of the deepest part of the pore” means that a perpendicular line is drawn with respect to the straight line 12 representing the fiber surface appearing on the image of the fiber cross section, as shown in FIGS. 1 (a) and 1 (b). The length of the longest straight line (FIGS. 1 (a) and (b)) connecting the intersection of the perpendicular and the inner wall of the pore and the intersection of the perpendicular and the straight line 12 representing the fiber surface. B).
[0053]
In addition, in the pores appearing on the image by a scanning electron microscope or the like of the fiber cross section in the fiber axis direction, the length of the pores is 0.6 to the opening width so that the adhesion with the active material is excellent. It is preferably 3 times, and more preferably 0.7 to 2 times. As shown in FIGS. 1 (c) and 1 (d), this “pore length” refers to points at both ends representing the outline of the aperture (A and B in FIGS. 1 (c) and 1 (d)). Refers to half the length of the path from one point to the other point along the line representing the inner wall of the pore, and the “opening width” is the distance between the two ends representing the contour of the opening. It refers to the length of a straight line connecting points (a in FIGS. 1C and 1D). In addition, the comparison value of the length of an opening and an opening width is taken as the number average comparison value by the sampling from arbitrary 500 or more pores.
[0054]
The number of the pores is 10000 μm on the fiber surface.²The number is preferably 10 to 55000, more preferably 10 to 1000, and still more preferably 50 to 1000. The number of the pores is 10000 μm on the fiber surface.²When the number is 10 or more, it is possible to increase the number of portions that are in close contact with the active material. Also, the fiber surface is 10000 μm²When the number is 55000 or less, the shape and size of the pores can be uniform, and the adhesiveness to the active material is excellent.
[0055]
The plated nonwoven fabric of the present invention includes the surface porous plated fiber as described above, but the amount is not particularly limited. However, the total fiber surface area per unit volume of the plated nonwoven fabric is 500 cm.²/ Cm³As described above, it is preferable that the surface porous plating fiber is included. In this way, when the total fiber surface area per unit volume is large, there are many contact points between the active material and the fibers (particularly the surface porous plating fibers), and as a result, the current collection is excellent and it is easier to manufacture a high capacity battery. Because. The larger the total fiber surface area per unit volume, the better the effect.²/ Cm³The above is more preferable.
[0056]
The “total fiber surface area per unit volume” is a value obtained as follows.
(1) Specific surface area A (m of plated nonwoven fabric by BET method²/ G) is measured.
(2) Based on this specific surface area A, the surface area Su per unit basis weight is calculated.
Su = A × W
Here, Su is the surface area per unit weight (m²/ M²), A is the specific surface area (m²/ G), W is a basis weight (g / m²).
(3) Based on the surface area Su per unit basis weight, the total fiber surface area Sv per unit volume is calculated.
Sv = Su / t
Here, Sv is the total fiber surface area per unit volume (cm²/ Cm³), Su is the surface area per unit weight (cm²/ Cm²) And t indicate the thickness (cm) of the plated nonwoven fabric.
[0057]
The plated nonwoven fabric constituting the current collector of the present invention is composed only of plated fibers having a plated layer on the surface, including the surface porous plated fibers as described above. As plating fibers other than the surface porous plating fiber, for example, fibers having pores other than the surface and having a plating layer on the surface, fibers having no pores at all and having a plating layer on the surface, etc. Can be included.
[0058]
In addition, although the plating fiber which comprises a plating nonwoven fabric does not need to be equipped with the plating layer on the whole fiber surface, it is in the state which the surface which does not have a plating layer is not exposed so that it may be excellent in current collection. preferable. For example, even if the surface of the contact between the plated fibers that make up the plated nonwoven fabric is not provided with a plating layer, the contact surface is not exposed, so the current collection performance of the plated nonwoven fabric (current collector) is hardly affected. Don't give.
Thus, the plating fiber which is not provided with the plating layer on the surface of a contact is easy to be formed when a plating process is performed after forming a nonwoven fabric.
[0059]
The plated nonwoven fabric of the present invention preferably has a porosity of 70% or more. This “porosity” refers to the percentage of pores with respect to the total volume of the plated nonwoven fabric. This is because if the porosity is 70% or more, the packing density of the active material synthetic paste can be increased, and as a result, it can contribute to the performance improvement as a current collector for electrodes of high capacity batteries. On the other hand, if the porosity is too high, a significant decrease in strength is caused, so the porosity is preferably 80 to 98%.
[0060]
The plated nonwoven fabric is preferably interspersed with a plurality of pores penetrating from one surface to the other surface. This is because, if a plurality of pores are scattered in the plated nonwoven fabric, these pores are filled with the active material, and the amount of the active material filled increases, so that the capacity of the battery can be increased. Such pores can be formed by locally dissolving or disappearing by punching formed by punching a non-plated nonwoven fabric, heat, laser processing, or the like.
[0061]
The above is a method for producing a plated nonwoven fabric, that is, a current collector, in which a surface porous fiber is formed from non-porous fibers, and then a nonwoven fabric is formed, and in some cases, a hydrophilic treatment and a plating treatment are sequentially performed. The electric material is not limited to this manufacturing method. For example, in order, (1) formation of surface porous fiber from nonporous fiber-hydrophilic treatment-formation of nonwoven fabric-plating treatment, (2) nonporous fiber to surface porous fiber Formation-Hydrophilization treatment-Plating treatment-Formation of non-woven fabric, (3) Formation of non-woven fabric using non-porous fiber-Formation of surface porous fiber from non-porous fiber-Hydrophilization treatment-Plating treatment, (4) Non-porous Formation of non-woven fabric using porous fibers-Hydrophilization treatment-Formation of surface porous fibers from non-porous fibers-Plating treatment, (5) Formation of non-woven fabric using non-porous fibers-Hydrophilization treatment-Plating treatment-Non-porous Surface fiber to porous fiber (6) Hydrophilization treatment of non-porous fibers-Formation of surface porous fibers from non-porous fibers-Formation of non-woven fabric-Plating treatment, (7) Hydrophilization treatment of non-porous fibers-From non-porous fibers Formation of surface porous fiber-plating treatment-formation of non-woven fabric, (8) hydrophilic treatment of non-porous fiber-formation of non-woven fabric-formation of surface porous fiber from non-porous fiber-plating treatment, (9) non-porous fiber Hydrophilization treatment-Formation of nonwoven fabric-Plating treatment-Formation of surface porous fiber from nonporous fiber, (10) Hydrophilization treatment of nonporous fiber-Plating treatment-Formation of surface porous fiber from nonporous fiber-Nonwoven fabric (11) Hydrophilization treatment of non-porous fibers-plating treatment-formation of nonwoven fabric-formation of surface porous fibers from non-porous fibers, and the like. Among these, when it is a method of performing a plating process after forming a surface porous fiber from a nonporous fiber like (1)-(4) or (6)-(8), in the surface of a surface porous fiber Since the pores and the plating layer are firmly bonded by the anchor effect, peeling of the plating layer from the surface porous plating fiber can be suppressed, and a battery with low internal resistance can be manufactured. is there.
[0062]
Next, as an example of a battery using the current collector according to the present invention, an alkaline secondary battery will be described with reference to FIGS.
[0063]
As shown in FIG. 2, the battery 101 is an alkaline secondary battery using a current collector made of a plated non-woven fabric including a surface porous plated fiber, and includes a belt-like positive electrode 102 and a belt-like negative electrode 103 made of the current collector. A first separator 104a is interposed between the positive electrode 102 and the negative electrode 103, and a roll-shaped power generator 106 in which a second separator 104b is interposed inside the positive electrode 102 is provided (FIG. 2). The battery 101 includes a conductive battery case 107 that houses a power generator 106 and also serves as a negative electrode, and an encapsulating plate 108 that seals the battery case 107 and also serves as a positive electrode.
[0064]
The positive electrode 102 is formed by forming the above-described current collector 10 in a strip shape, crushing a portion to which a terminal is attached, filling a positive electrode paste containing a positive electrode active material in the voids of the entire current collector, and then drying and rolling. And it is made by spot welding the nickel piece 102a as an external terminal for current collection in the crushed location. Further, the negative electrode 103 is formed by forming the above-described current collector into a strip shape, crushing a portion to which a terminal is attached, filling a gap portion of the entire current collector with a negative electrode paste containing a negative electrode active material, and then drying and rolling. And it is made by spot-welding a nickel piece (not shown) as a current collecting external terminal to the crushed portion. On the other hand, the separator 104 is formed in a band shape by a porous sheet, and includes a first separator 104 a interposed between the positive electrode 102 and the negative electrode 103, and a second separator 104 b stacked on the inner surface of the positive electrode 102. The first and second separators 104a and 104b are configured to prevent a short circuit between the positive electrode 102 and the negative electrode 103 and hold the electrolyte.
[0065]
The conductive battery case 107 is formed in a cylindrical shape having a can bottom 107 a, and the enclosing plate 108 is configured to close the opening at the upper end of the battery case 107. The battery case 107 is configured such that the power generation body 106 can be accommodated so that the negative electrode 103 contacts the inner peripheral surface thereof. In addition, a protrusion 108a that forms the positive terminal of the battery is formed at the center of the encapsulating plate 108. Further, a lower insulator 109a is interposed between the can bottom 107a and the power generator 106. The power generator 106 is inserted into a battery case 107 in which a lower insulator 109 a is inserted, and an upper insulator 109 b is disposed at the upper end of the power generator 106.
[0066]
The lower insulator 109 a is formed with a slit through which the nickel piece spot welded to the negative electrode 103 can be inserted, and the upper insulator 109 b is formed with a slit through which the nickel piece 102 a spot welded to the positive electrode 102 can be inserted. The nickel piece spot-welded to the negative electrode 103 is inserted through the slit formed in the lower insulator 109a and protrudes toward the can bottom 107a, and the nickel piece 102a spot-welded to the positive electrode 102 is the slit formed in the upper insulator 109b. Is inserted and protruded toward the enclosing plate 108 side. The nickel piece protruding from the slit of the lower insulator 109a is connected to the can bottom 107a, and the nickel piece 102a protruding from the slit of the upper insulator 109b is connected to the encapsulating plate 108.
[0067]
In a state where the upper insulator 109b is inserted into the battery case 107, a ring-shaped constricted portion 107b is formed in the upper part in the vicinity of the opening of the battery case 107, and then an electrolytic solution is injected. After that, the encapsulating plate 108 to which the nickel piece 102a of the positive electrode 102 is connected is disposed on the constricted portion 107b via the ring-shaped insulating packing 111. Thereafter, the upper edge of the battery case 107 is folded back and the outer peripheral edge of the encapsulating plate 108 is covered with the insulating packing 111, whereby the encapsulating plate 108 is electrically insulated from the battery case 107, and the battery case is sealed by the encapsulating plate 108. The
[0068]
In the battery 101 configured as described above, the second separator 104b, the positive electrode 102, the first separator 104a, and the negative electrode 103 are stacked in this order. In such a laminated state, the power generator 106 is manufactured by winding in a roll shape so that the negative electrode 103 is on the outside, but the current collector including the surface porous plating fiber is a net-like structure made of conventional nickel. Since it is relatively flexible compared to a current collector made of a skeleton, the positive electrode 102 and the negative electrode 103 using this current collector are also relatively flexible, and it is relatively easy to wind in a roll shape. The battery 101 itself can be easily assembled.
[0069]
In addition, since the current collecting material including the surface porous plating fiber is excellent in current collecting property, the amount of fibers constituting the current collecting material can be reduced, and the porosity of the current collecting material can be increased. Since the filling amount can be increased, a high-capacity battery can be manufactured.
[0070]
In the above-described embodiment, the battery in which the power generator 106 wound in a roll shape is inserted into the cylindrical battery case 107 has been described. However, the battery case may be a rectangular tube, 4 may be one in which the positive electrode 102 and the negative electrode 103 are wound in a spiral shape as shown in FIG. 4, or one that is bent and laminated in a bellows shape as shown in FIG.
[0071]
Examples of the current collector of the present invention will be described below, but the present invention is not limited to the following examples.
[0072]
【Example】
Example 1
A core-sheath type composite fiber having a core component made of polypropylene, a sheath component made of high-density polyethylene (melting point: 135 ° C.), a fineness of 11 dtex (fiber diameter: 39 μm) and a fiber length of 5 mm A fiber web was formed from the slurry in which 100% by weight of the cross-sectional shape (circular) occupied was dispersed by a wet papermaking method. This fiber web was heat-treated with a dryer set at a temperature of 135 ° C., and the sheath component of the core-sheath composite fiber was fused, and the basis weight was 120 g / cm.²A non-woven fabric having a thickness of 1.5 mm was manufactured.
[0073]
Next, the nonwoven fabric is immersed in fuming sulfuric acid at a temperature of 80 ° C. to perform sulfonation treatment, and the sulfonation degree is 2.0 × 10 6.^-3A sulfonated nonwoven fabric was produced.
[0074]
Next, sodium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was pulverized by using a pulverizer to obtain sodium chloride fine particles having an average primary particle size of 8.0 μm.
[0075]
Next, 100 g of this sodium chloride fine particle was placed in a petri dish having a diameter of 15 cm, heated in a dryer set at a temperature of 140 ° C. for 30 minutes or more with the lid on, and immediately after the petri dish was taken out of the dryer, the sulfonated nonwoven fabric ( 10 cm square) was put in a petri dish, and the petri dish was quickly vibrated for 30 seconds as it was to fix sodium chloride fine particles to the entire sulfonated non-woven fabric to produce a sodium chloride fine particle fixed sulfonated non-woven fabric. Thereafter, the sodium chloride fine particle-fixed sulfonated nonwoven fabric was washed with water to remove sodium chloride fine particles, and a sulfonated nonwoven fabric composed of surface porous fibers having pores formed only on the surface was produced.
[0076]
Subsequently, the sulfonated nonwoven fabric made of surface porous fibers was put into a beaker into which the refining agent was poured, and the sulfonated nonwoven fabric was washed with water after stirring the sulfonated nonwoven fabric with a stirrer so that the refining agent could permeate.
[0077]
Next, the sulfonated nonwoven fabric is put into a beaker into which an aqueous solution containing 10 g / L of stannous chloride and 20 mL / L of hydrochloric acid is poured, and the sulfonated nonwoven fabric is stirred with a stirrer so that the aqueous solution can pass through. The non-woven fabric was washed with water.
Thereafter, the sulfonated nonwoven fabric is poured into a beaker into which an aqueous solution containing 1 g / L of palladium chloride and 20 mL / L of hydrochloric acid has been poured, and the sulfonated nonwoven fabric is stirred with a stirrer so that the aqueous solution can pass through. Was catalyzed.
[0078]
Then, after washing the catalyzed sulfonated non-woven fabric with water, electroless nickel plating solution having concentrations of nickel sulfate 18 g / L, sodium citrate 10 g / L, hydrated hydrazine 50 mL / L, and 25% aqueous ammonia 100 mL / L. Into the beaker into which the solution was injected, the catalyst-sulfonated non-woven fabric was stirred with a stirrer for 1 hour so that the plating solution permeated while heating to 80 ° C., and electroless plating was performed.
[0079]
Thereafter, the sulfonated non-woven fabric that has undergone the plating process is taken out, washed with water, and further dried to produce a plated non-woven fabric with a plating ratio of 50%, that is, a current collector (weight per unit: 240 g / m).², Thickness: 1.5 mm, porosity: 91%, total fiber surface area per unit volume of plated nonwoven fabric: 600 cm²/ Cm³, Semi-spherical shape, shape of the aperture: substantially polygonal, average diameter of the aperture: 5.0 μm, major axis of the aperture / minor axis of the aperture = 1.2, average depth of the pores: 3.0 μm, pore length: 1.4 times the pore width, number of pores: 500/10000 μm²) The plating ratio (R) is a value obtained by the following formula.
R = {(Wa−Wb) / Wa} × 100
Here, R means the plating ratio (%), Wa is the weight after plating, that is, the basis weight of the current collector (g / m²Wb is the weight before plating, that is, the basis weight (g / m) of the sulfonated nonwoven fabric composed of surface porous fibers.²).
[0080]
(Comparative Example 1)
The sulfonated nonwoven fabric produced in the same manner as in Example 1 was subjected to a plating treatment without subjecting the core-sheath type composite fiber to the surface porosity treatment, and a plated nonwoven fabric having a plating ratio of 50%, that is, a current collector (weight per unit: 240 g) / M², Thickness: 1.5 mm, porosity: 90%, total fiber surface area per unit volume of plated nonwoven fabric: 400 cm²/ Cm³)
[0081]
(Example 2)
Except that the vibration time in the petri dish was set to 5 seconds, a sulfonated nonwoven fabric made of surface porous fibers was produced in exactly the same manner as in Example 1.
[0082]
Next, the sulfonated nonwoven fabric composed of the surface porous fibers was plated in the same manner as in Example 1, and a plated nonwoven fabric having a plating ratio of 50%, that is, a current collector (weight per unit: 240 g / m).², Thickness: 1.5 mm, porosity: 91%, total fiber surface area per unit volume of plated nonwoven fabric: 500 cm²/ Cm³, Semi-spherical shape, shape of the aperture: substantially polygonal, average diameter of the aperture: 5.0 μm, major axis of the aperture / minor axis of the aperture = 1.2, average depth of the pores: 3.0 μm, pore length: 1.4 times the opening width, number of pores: 400/10000 μm²)
[0083]
(Comparative Example 2)
A core-sheath type composite fiber having a core component made of polypropylene, a sheath component made of high-density polyethylene (melting point: 135 ° C.), a fineness of 6.6 dtex (fiber diameter: 30 μm) and a fiber length of 5 mm (the entire fiber surface is sheathed) A fiber web was formed from a slurry in which 100% by weight of the cross-sectional shape occupied by the component was dispersed by a wet papermaking method. This fiber web was heat-treated with a dryer set at a temperature of 135 ° C., and the sheath component of the core-sheath composite fiber was fused, and the basis weight was 120 g / cm.²A nonwoven fabric having a thickness of 1 mm was manufactured.
[0084]
Next, the nonwoven fabric is immersed in fuming sulfuric acid at a temperature of 80 ° C. to perform sulfonation treatment, and the sulfonation degree is 2.0 × 10.^-3A sulfonated nonwoven fabric was produced.
[0085]
Next, this sulfonated nonwoven fabric was subjected to a plating treatment in the same manner as in Example 1 without subjecting the core-sheath type composite fiber to a surface porosity treatment, and a plated nonwoven fabric having a plating ratio of 50%, that is, a current collector (weight per unit: 240 g / m², Thickness: 1 mm, porosity: 83%, total fiber surface area per unit volume of plated nonwoven fabric: 600 cm²/ Cm³)
[0086]
(Comparative Example 3)
After mixing the solid particles and spinning the fiber, an entire porous fiber (fineness: 11 dtex, fiber length: 5 mm) having pores on the fiber surface and inside the fiber was prepared by extracting and removing the solid particles.
[0087]
Next, 80 mass% of the whole porous fiber, the core component is made of polypropylene, and the sheath component is made of high-density polyethylene (melting point: 135 ° C.), the core-sheath type composite fiber (fineness: 2.2 dtex, fiber length: 10 mm) 20 mass %, A fiber web was formed by a wet papermaking method. This fiber web was heat-treated with a dryer set at a temperature of 135 ° C., and the sheath component of the core-sheath composite fiber was fused, and the basis weight was 120 g / cm.²A non-woven fabric having a thickness of 1.2 mm was manufactured.
[0088]
Next, the nonwoven fabric was subjected to sulfonation treatment and plating treatment in the same manner as in Example 1, and a plated nonwoven fabric having a plating ratio of 50%, that is, a current collector (weight per unit: 240 g / m).², Thickness: 1.2 mm, porosity: 85%, total fiber surface area per unit volume of plated nonwoven fabric: 500 cm²/ Cm³Sponge, shape of the aperture: substantially circular, average diameter of the aperture: 1 μm, long diameter of the aperture / short diameter of the aperture = 1.1, average depth of the pore: more than 15 μm, fine Pore length: more than 3 times the opening width, number of pores: 8000/10000 μm²)
[0089]
(Peel test)
Adhesive tape (Nitto Denko Co., Ltd., Nitto 31B) was applied to each current collector, and after pressing strongly with a finger, one end of the adhesive tape was pulled and the adhesive tape was pulled away from the current collector, then nickel in the current collector The presence or absence of plating peeling was observed. The results are shown in Table 1.
[0090]
(Measurement of utilization rate)
Using the current collectors of Examples and Comparative Examples for the positive electrode and nickel foam for the negative electrode, AA (AA) type batteries (the theoretical capacity of the batteries of Examples 1 to 3 and Comparative Example 1: 1200 mAh, comparison The theoretical capacity of the battery of Example 2 was 950 mAh, and the theoretical capacity of the battery of Comparative Example 3 was 1000 mAh.
[0091]
Next, after each battery was activated by charging / discharging at a temperature of 20 ° C. and 0.1 C (120 mAh), it was further charged and discharged for 5 cycles at 0.1 C, and from the average of the discharge capacity of 5 cycles, 0.1 C was used. The rate was calculated.
[0092]
Next, charge and discharge was performed for 5 cycles with a test current of 4.0 C (4800 mAh), and a 4.0 C utilization factor was calculated from an average of the discharge capacities for 5 cycles. The utilization rate (U, unit:%) was calculated by the following formula.
U = (C₅/ Ct) × 100
Here, U represents the utilization rate (%), and C₅Represents the average (mAh) of the discharge capacity of 5 cycles, and Ct represents the theoretical capacity (mAh).
[0093]
[Table 1]

[0094]
As is apparent from the results of the theoretical battery capacity shown in Table 1, the current collecting material including the surface porous plating fiber of the present invention can be increased in capacity and has excellent current collecting performance.
Further, as is apparent from the result of 4.0C utilization rate, the current collector of the present invention was excellent in current collection performance in high rate discharge.
[0095]
【The invention's effect】
The current collector of the present invention is excellent in current collection. Moreover, a high capacity | capacitance battery can be manufactured.
[0096]
The battery of the present invention is excellent in current collecting performance and can be a high capacity battery.
[Brief description of the drawings]
FIG. 1A is a schematic cross-sectional image of a surface porous plating fiber of the present invention.
(B) Schematic cross-sectional image of another surface porous plating fiber of the present invention
(C) Cross-sectional image schematic diagram in the fiber axis direction of the surface porous plating fiber of the present invention
(D) Cross-sectional image schematic diagram in the fiber axis direction of another surface porous plating fiber of the present invention
FIG. 2 is a perspective view in which a part of the alkaline secondary battery of the present invention is cut away.
3 is a cross-sectional view taken along line AA of FIG. 2 in which the current collector is wound in a spiral shape.
4 is a cross-sectional view corresponding to FIG. 3 in which the current collector is wound in a spiral shape.
FIG. 5 is a cross-sectional view corresponding to FIG. 3 in which the current collector is bent and stacked in a bellows shape.
[Explanation of symbols]
10 Surface porous plating fiber
11 pores
12 Fiber surface
13 Opening
101 battery
102 positive electrode
102a Nickel piece
103 negative electrode
104 separator
104a First separator
104b Second separator
106 Power generator
107 Battery case
107a can bottom
107b Constriction
108 Encapsulation plate
108a protrusion
109a Lower insulator
109b Upper insulator

Claims (3)

It is a current collector for a battery comprising a plated non-woven fabric composed only of a plated fiber having a plated layer on the surface of a fiber mainly comprising a thermoplastic resin, and the surface of the fiber is 10,000 μm as the plated fiber. ² The surface perforated plating fiber having 10 to 55000 pores per hole, and the surface perforated plating fiber is formed only in the surface thereof, and the shape of the opening portion of the pore is substantially circular or substantially polygonal, A battery current collector, wherein pores having an average diameter of an aperture of 0.5 to 15 μm and an average depth of 0.1 to 15 μm are formed. ^2. The battery current collector according to claim 1, wherein a total fiber surface area per unit volume of the plated nonwoven fabric is 500 cm ² / cm ³ or more. A battery using the battery current collector according to claim 1 .

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