JP2006236685A - Negative electrode, battery, and their manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative electrode capable of improving cycle characteristics, and a battery using it, and their manufacturing methods. <P>SOLUTION: A negative electrode current collector 12 made of a metallic material such as Cu is formed by plating so as to cover negative an electrode active material particle 11 containing Sn as a constituent element. Even if the particle 11 is expanded and contracted due to charging and discharging, the collector 12 may suppress the collapse of the shape of the particle 11, and also the contact performance between the particle 11 and the collector 12 may be enhanced to suppress reduction in current collecting property. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a negative electrode and a battery using a negative electrode active material containing tin as a constituent element, and a method for producing them.

In recent years, as mobile devices have higher performance and more functions, there is a demand for higher capacities of secondary batteries as power sources thereof. Secondary batteries that meet this demand include lithium ion secondary batteries, but those currently in practical use use graphite for the negative electrode, so the battery capacity is in a saturated state, and there is a significant increase in capacity. difficult. Therefore, a high capacity negative electrode using tin (Sn) or tin alloy as the negative electrode has been studied (for example, see Patent Document 1).
JP 2004-171876 A

  However, since tin or tin alloy has a large expansion / contraction due to charging / discharging, the negative electrode active material layer falls off from pulverization or the current collector, so that the current collecting property is lowered and the cycle characteristics are deteriorated. There was a problem.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a negative electrode and a battery that can improve cycle characteristics by improving current collecting performance, and a method for manufacturing the same.

  The first negative electrode according to the present invention has negative electrode active material particles containing tin as a constituent element, and a negative electrode current collector having the negative electrode active material particles therein.

  The second negative electrode according to the present invention has negative electrode active material particles containing tin as a constituent element and a negative electrode current collector formed by plating so as to cover the negative electrode active material particles.

  The third negative electrode according to the present invention has a particulate negative electrode current collector and an electrode reaction part that has this negative electrode current collector inside and contains tin as a constituent element.

  The fourth negative electrode according to the present invention has a particulate negative electrode current collector and an electrode reaction part containing tin as a constituent element formed by plating so as to cover the negative electrode current collector.

  A first battery according to the present invention includes an electrolyte together with a positive electrode and a negative electrode. The negative electrode includes negative electrode active material particles containing tin as a constituent element, and a negative electrode current collector having the negative electrode active material particles therein. It has.

  A second battery according to the present invention is provided with an electrolyte together with a positive electrode and a negative electrode, and the negative electrode is formed by plating so as to cover negative electrode active material particles containing tin as a constituent element and the negative electrode active material particles. Negative electrode current collector.

  A third battery according to the present invention includes an electrolyte together with a positive electrode and a negative electrode. The negative electrode has a particulate negative electrode current collector and the negative electrode current collector therein, and tin is a constituent element. Including an electrode reaction part.

  A fourth battery according to the present invention is provided with an electrolyte together with a positive electrode and a negative electrode, and the negative electrode is a particulate negative electrode current collector and tin formed by plating so as to cover the negative electrode current collector. And an electrode reaction part containing as a constituent element.

  In the first negative electrode manufacturing method according to the present invention, a negative electrode active material particle containing tin as a constituent element is supported on a substrate, and a negative electrode current collector is formed by plating so as to cover the negative electrode active material particle. And a step of peeling the substrate after forming the negative electrode current collector.

  In the second negative electrode manufacturing method according to the present invention, a particulate negative electrode current collector is supported on a substrate, and an electrode reaction part containing tin as a constituent element is formed by plating so as to cover the negative electrode current collector. And a step of peeling the substrate after forming the electrode reaction part.

  A first battery manufacturing method according to the present invention is to manufacture a battery including an electrolyte together with a positive electrode and a negative electrode. The negative electrode carries negative electrode active material particles containing tin as a constituent element on a base material. The negative electrode current collector is formed so as to cover the negative electrode active material particles by plating, and then the substrate is peeled off.

  The second battery manufacturing method according to the present invention is to manufacture a battery including an electrolyte together with a positive electrode and a negative electrode. The negative electrode carries a particulate negative electrode current collector on a substrate, After forming the electrode reaction part which contains tin as a structural element so that a negative electrode electrical power collector may be coat | covered, it forms by peeling a base material.

  According to the first or second negative electrode of the present invention, the negative electrode active material particles are provided inside the negative electrode current collector or the negative electrode active material particles are covered with the negative electrode current collector. The shape of the active material particles can be prevented from collapsing, the contact between the negative electrode active material particles and the negative electrode current collector can be increased, and the decrease in current collection due to the expansion and contraction of the negative electrode active material particles can be suppressed. be able to. Further, according to the third or fourth negative electrode of the present invention, the particulate negative electrode current collector is covered with the electrode reaction part so as to have the particulate negative electrode current collector inside the electrode reaction part. Since it did in this way, the contact property of a negative electrode collector and an electrode reaction part can be made high, and the fall of the current collection property by the expansion / contraction of an electrode reaction part can be suppressed. Therefore, according to the first to fourth batteries of the present invention using these negative electrodes, excellent cycle characteristics can be obtained. Further, for example, the volume ratio of the current collector used in the battery can be reduced, and the volume energy density can be improved.

  In particular, if the average particle diameter of the negative electrode active material particles or the particulate negative electrode current collector is in the range of 0.01 μm or more and 20 μm or less, a higher effect can be obtained.

  Furthermore, if the negative electrode active material particles and the negative electrode current collector, or the particulate negative electrode current collector and the electrode reaction part are alloyed at least at a part of the interface, the contact between them is further improved. be able to.

  According to the first and second negative electrode manufacturing methods or the first and second battery manufacturing methods of the present invention, negative electrode active material particles are supported on a substrate, and a negative electrode current collector is formed by plating. Since the electrode negative electrode current collector is formed on the substrate and the electrode reaction part is formed by plating, the first to fourth negative electrodes or the first to fourth negative electrodes of the present invention are formed. 4 batteries can be easily manufactured.

  Further, if annealing treatment or pressure treatment is performed, at least a part of the interface between the negative electrode active material particles and the negative electrode current collector or the negative electrode current collector and the electrode reaction part can be alloyed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 schematically shows a cross-sectional configuration of the negative electrode 10 according to the first embodiment.

  The negative electrode 10 includes negative electrode active material particles 11 containing tin as a constituent element, and a negative electrode current collector 12 having the negative electrode active material particles 11 therein. As a result, even if the negative electrode active material particles 11 expand and contract due to the electrode reaction, pulverization is suppressed, and the contact between the negative electrode active material particles 11 and the negative electrode current collector 12 is maintained, and the current collection performance is reduced. It is supposed to be suppressed. Note that the negative electrode active material particles 11 need not all be present inside the negative electrode current collector 12, and a part of the negative electrode active material particles 11 may be exposed from the surface of the negative electrode current collector 12.

  The negative electrode active material particles 11 may be a simple substance of tin, an alloy, or a compound, and may have one or more of these phases in at least a part thereof. In the present invention, alloys include those containing one or more metal elements and one or more metalloid elements in addition to those composed of two or more metal elements. Moreover, the nonmetallic element may be included. Some of the structures are solid solutions, eutectics (eutectic mixtures), intermetallic compounds, or those in which two or more of them coexist.

  Examples of the tin alloy include silicon (Si), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), manganese (Mn), and zinc (second constituent elements other than tin). A material containing at least one selected from the group consisting of Zn), indium (In), silver (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb), and chromium (Cr) Can be mentioned. Examples of the tin compound include those containing oxygen (O) or carbon (C), and may contain the second constituent element described above in addition to tin.

  Further, the negative electrode active material particles 11 are preferably alloyed with the negative electrode current collector 12 at least at a part of the interface thereof. Specifically, the constituent elements of the negative electrode active material particles 11 are diffused in the negative electrode current collector 12, the constituent elements of the negative electrode current collector 12 are diffused in the negative electrode active material particles 11, or they are mutually diffused at the interface. preferable. This is because the contact property can be further improved.

  The average particle diameter of the negative electrode active material particles 11 is preferably in the range of 0.01 μm to 20 μm. If the average particle size is small, side reaction with the electrolytic solution is promoted due to an increase in specific surface area, and a film grows around the negative electrode active material particles 11 to inhibit the electrode reaction. In addition, even if the average particle size is large, the specific surface area is small, the contact area between the negative electrode active material particles 11 and the negative electrode current collector 12 is reduced, and the capacity is reduced. .

  The negative electrode current collector 12 is preferably made of a porous material, for example, and is preferably partially joined to the negative electrode active material particles 11. This is because the reactivity of the negative electrode active material particles 11 can be improved. The constituent material of the negative electrode current collector 12 is preferably a metal material having low reactivity with respect to the electrode reactant that is occluded and released by the negative electrode active material particles 11. For example, when lithium is used as the electrode reactant, one containing a metal element that does not form an intermetallic compound with lithium is preferable. If the reactivity with the electrode reactant is high, the negative electrode current collector 12 also expands and contracts due to the electrode reaction, structural destruction occurs, and the current collecting property is lowered, and the ability to support the negative electrode active material particles 11 is small. Because it becomes. Among these, copper, nickel, iron, or an alloy thereof is preferable because of high electron conductivity.

  Further, the negative electrode 10 may include a binder for binding the negative electrode active material particles 11 together with the negative electrode active material particles 11.

  This negative electrode 10 can be manufactured as follows, for example.

  FIG. 2 shows the manufacturing process in order. First, for example, the negative electrode active material particles 11 are mixed using a dispersion medium such as N-methyl-pyrrolidone to prepare a slurry having an appropriate viscosity. At that time, it is preferable to disperse the binder together with the negative electrode active material particles 11. Subsequently, a base material 20 is prepared as shown in FIG. 2 (A), and this slurry is applied to the surface of the base material 20 and dried to form a coating film 21 as shown in FIG. 2 (B). The negative electrode active material particles 11 are supported. The substrate 20 is preferably made of a metal material such as stainless steel, for example. Further, it may be made of a resin material such as acrylic resin, phenol resin, epoxy resin, polyester or polyvinyl chloride (PVC), and an electrically conductive resin obtained by mixing a conductive substance with these materials, or a catalyst for these resins. You may make it comprise what was carry | supported or what formed the electroconductive film | membrane in these resin.

  Next, the negative electrode current collector 12 is formed by a plating method. As the plating method, either an electrolytic plating method or an electroless plating method may be used. The negative electrode current collector 12 is formed as follows. First, as shown in FIG. 2C, metal particles 12 </ b> A constituting the negative electrode current collector 12 are deposited between the base material 20 and the coating film 21. At this time, since the coating film 21 serves as a shielding plate for the base material 20 and the current density on the surface of the base material 20 is reduced, the deposited particles 12A are small and have a dense and uniform shape.

  Subsequently, as shown in FIG. 2 (D), the particles 12A are deposited along the negative electrode active material particles 11 of the coating film 21, and further, as shown in FIG. 2 (E), the surface of the coating film 21 It precipitates in. At this time, since the surface of the coating film 21 has nothing to serve as a shielding plate, the current density is high and the precipitated particles 12A are also large.

  After the negative electrode current collector 12 is formed, the negative electrode current collector 12 is peeled off from the substrate 20 to complete the negative electrode 10 shown in FIG. The negative electrode current collector 12 is preferably formed of copper, nickel, or iron. This is because the adhesive strength with the base material 20 is low and it is easy to peel off. In addition, after the negative electrode current collector 12 is formed, it is preferable to perform an annealing process in a vacuum atmosphere, an air atmosphere, a reducing atmosphere, an oxidizing atmosphere, or an inert atmosphere. This is because at least a part of the interface between the negative electrode active material particles 11 and the negative electrode current collector 12 can be alloyed. Further, after the negative electrode current collector 12 is formed, a pressure treatment may be performed. This is because the volume energy density can be improved and the contact between the negative electrode active material particles 11 and the negative electrode current collector 12 can be improved. These treatments may be performed before or after the substrate 20 is peeled off, and only one of them or both may be carried out.

  This negative electrode 10 is used for the following secondary batteries, for example. Note that in this embodiment, the case where lithium is used as an electrode reactant is described.

  FIG. 3 shows the configuration of the secondary battery. This secondary battery is a so-called coin-type battery, in which the negative electrode 10 accommodated in the exterior cup 31 and the positive electrode 33 accommodated in the exterior can 32 are stacked via a separator 34. is there. The peripheral portions of the outer cup 31 and the outer can 32 are sealed by caulking through an insulating gasket 35. The exterior cup 31 and the exterior can 32 are made of, for example, a metal such as stainless steel or aluminum (Al).

  The positive electrode 33 includes, for example, a positive electrode current collector 33A and a positive electrode active material layer 33B provided on the positive electrode current collector 33A. The positive electrode current collector 33A is made of, for example, aluminum, nickel, stainless steel, or the like.

The positive electrode active material layer 33B includes, for example, any one or more of positive electrode materials capable of inserting and extracting lithium as a positive electrode active material, and a conductive agent such as a carbon material and the like as necessary. A binder such as polyvinylidene fluoride may be included. As a positive electrode material capable of inserting and extracting lithium, for example, a lithium-containing metal composite oxide represented by a general formula Li _x MIO ₂ is preferable. This is because the capacity can be increased. MI is one or more transition metals, and for example, at least one of the group consisting of cobalt, nickel and manganese is preferable. x varies depending on the charge / discharge state of the battery and is usually a value in the range of 0.05 ≦ x ≦ 1.10. Specific examples of such a lithium-containing metal composite oxide include LiCoO _{2 and} LiNiO ₂ .

  The separator 34 separates the negative electrode 10 and the positive electrode 33 and allows lithium ions to pass while preventing a short circuit of current due to contact between both electrodes, and is made of, for example, polyethylene or polypropylene.

  The separator 34 is impregnated with an electrolytic solution that is a liquid electrolyte. This electrolytic solution contains, for example, a solvent and a lithium salt that is an electrolyte salt dissolved in this solvent, and may contain various additives as necessary. It is preferable to use the electrolytic solution in this way because high ionic conductivity can be obtained. Examples of the solvent include nonaqueous solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Any 1 type may be used for a solvent and 2 or more types may be mixed and used for it.

Examples of the lithium salt include LiPF _{6 and} LiClO ₄ . Any one lithium salt may be used, or two or more lithium salts may be mixed and used.

  The secondary battery can be manufactured, for example, by laminating the positive electrode 33, the separator 34 impregnated with the electrolytic solution, and the negative electrode 10, placing them in the outer can 32 and the outer cup 31, and caulking them. it can.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 33 and inserted in the negative electrode 10 through the electrolytic solution. When discharging is performed, for example, lithium ions are released from the negative electrode 10 and inserted into the positive electrode 33 through the electrolytic solution. The negative electrode active material particles 11 are greatly expanded and contracted with this charge / discharge, but the negative electrode active material particles 11 are present inside the negative electrode current collector 12, so that the negative electrode active material particles 11 and the negative electrode current collector 12 Contactability is maintained.

  The negative electrode 10 according to the present embodiment may be used for a secondary battery as follows.

  FIG. 4 is an exploded view of the secondary battery. In this secondary battery, an electrode winding body 40 to which a positive electrode lead 41 and a negative electrode lead 42 are attached is housed in a film-like exterior member 50, and can be reduced in size, weight, and thickness. ing.

  The positive electrode lead 41 and the negative electrode lead 42 are led out from the inside of the exterior member 50 to the outside, for example, in the same direction. The positive electrode lead 41 and the negative electrode lead 42 are each made of a metal material such as aluminum, copper, nickel, or stainless steel, and each have a thin plate shape or a mesh shape.

  The exterior member 50 is made of, for example, a rectangular aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. For example, the exterior member 50 is disposed so that the polyethylene film side and the electrode winding body 40 face each other, and the outer edge portions are in close contact with each other by fusion bonding or an adhesive. An adhesion film 43 is inserted between the exterior member 50 and the positive electrode lead 41 and the negative electrode lead 42 to prevent intrusion of outside air. The adhesion film 43 is made of a material having adhesion to the positive electrode lead 41 and the negative electrode lead 42, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  The exterior member 50 may be made of a laminated film having another structure, a polymer film such as polypropylene, or a metal film instead of the above-described aluminum laminated film.

  FIG. 5 shows a cross-sectional structure taken along line II of the electrode winding body 40 shown in FIG. The electrode winding body 40 is obtained by laminating the negative electrode 10 and the positive electrode 44 via the separator 45 and the electrolyte layer 46, and the outermost periphery is protected by a protective tape 47.

  The positive electrode 44 has a structure in which a positive electrode active material layer 44B is provided on both surfaces of a positive electrode current collector 44A. The configurations of the positive electrode current collector 44A, the positive electrode active material layer 44B, and the separator 45 are the same as those of the positive electrode current collector 33A, the positive electrode active material layer 33B, and the separator 34, respectively.

  The electrolyte layer 46 is configured by a so-called gel electrolyte in which an electrolytic solution is held in a holding body. A gel electrolyte is preferable because high ion conductivity can be obtained and battery leakage can be prevented. The configuration of the electrolytic solution (that is, the solvent and the electrolyte salt) is the same as that of the coin-type secondary battery shown in FIG.

  The holding body is made of, for example, a polymer compound. Examples of the polymer compound include polyvinylidene fluoride or a copolymer of vinylidene fluoride.

  This secondary battery can be manufactured, for example, as follows.

  First, the electrolyte layer 46 in which the electrolytic solution is held in the holding body is formed on each of the positive electrode 44 and the negative electrode 10. Next, the positive electrode lead 41 is attached to the end portion of the positive electrode current collector 44 </ b> A, and the negative electrode lead 42 is attached to the end portion of the negative electrode 10. Subsequently, the positive electrode 44 and the negative electrode 10 on which the electrolyte layer 46 is formed are laminated through a separator 45 to form a laminated body, and then the laminated body is wound in the longitudinal direction, and the protective tape 47 is attached to the outermost peripheral portion. The electrode winding body 40 is formed by bonding. After that, for example, the electrode winding body 40 is sandwiched between the exterior members 50, and the outer edges of the exterior members 50 are sealed and sealed by thermal fusion or the like. At that time, the adhesion film 43 is inserted between the positive electrode lead 41 and the negative electrode lead 42 and the exterior member 50. Thereby, the secondary battery shown in FIGS. 4 and 5 is completed.

  The operation of this secondary battery is the same as that of the coin-type secondary battery shown in FIG.

  Thus, according to the present embodiment, the negative electrode active material particles 11 are covered with the negative electrode current collector 12 so as to have the negative electrode active material particles 11 inside the negative electrode current collector 12, While the shape collapse of the negative electrode active material particles 11 can be suppressed, the contact between the negative electrode active material particles 11 and the negative electrode current collector 12 can be increased, and the current collecting property due to the expansion and contraction of the negative electrode active material particles 11 can be improved. Can be suppressed. Therefore, excellent cycle characteristics can be obtained. Further, the volume ratio of the negative electrode current collector in the battery can be reduced, and the volume energy density can be improved.

  In particular, if the average particle diameter of the negative electrode active material particles 11 is in the range of 0.01 μm or more and 20 μm or less, a higher effect can be obtained.

  Furthermore, if the negative electrode active material particles 11 and the negative electrode current collector 12 are alloyed in at least a part of the interface, the contact properties can be further improved.

(Second Embodiment)
FIG. 6 schematically illustrates a cross-sectional configuration of the negative electrode 60 according to the second embodiment.

  The negative electrode 60 includes a particulate negative electrode current collector 61 and an electrode reaction part 62 that has the negative electrode current collector 61 inside and contains tin as a constituent element. Thereby, even if the electrode reaction part 62 expands and contracts due to the electrode reaction, the contact property between the negative electrode current collector 61 and the electrode reaction part 62 is maintained, and the reduction of the current collection property is suppressed. Note that the negative electrode current collector 61 does not necessarily have to be entirely present inside the electrode reaction unit 62, and a part of the negative electrode current collector 61 may be exposed from the surface of the electrode reaction unit 62.

  The negative electrode current collector 61 is preferably made of the same material as the negative electrode current collector 12 described in the first embodiment, for example. The negative electrode current collector 61 is preferably alloyed with the electrode reaction part 62 at least at a part of the interface. This is because the contact property can be further improved.

  The average particle diameter of the negative electrode current collector 61 is preferably in the range of 0.01 μm to 20 μm. This is because if the average particle size is small, side reaction with the electrolytic solution is promoted due to an increase in the specific surface area, and the characteristics deteriorate. Moreover, even if the average particle size is large, the specific surface area is small, and the contact area is lowered due to the reduction of the contact area between the negative electrode current collector 61 and the electrode reaction part 62, and the capacity is reduced.

  The electrode reaction part 62 contains the material which contains tin as a structural element as a negative electrode active material, for example, is comprised with the material similar to the negative electrode active material particle 11 demonstrated in 1st Embodiment. Moreover, it is preferable that the electrode reaction part 62 consists of a porous body. This is because the reactivity of the electrode reaction part 62 can be improved.

  The negative electrode 60 may further include a binder for binding the negative electrode current collector 61 together with the negative electrode current collector 61.

  This negative electrode 60 can be manufactured as follows, for example.

  First, for example, the particulate negative electrode current collector 61 is mixed using a dispersion medium such as N-methyl-pyrrolidone to prepare a slurry having an appropriate viscosity. At that time, it is preferable to disperse the binder together with the negative electrode current collector 61. Subsequently, a base material is prepared, this slurry is applied to the surface of the base material and dried to form a coating film, and the negative electrode current collector 61 is supported. As the substrate, for example, the same material as in the first embodiment can be used.

  Next, the electrode reaction part 62 is formed by a plating method. In that case, the electrode reaction part 62 is formed as follows. First, particles containing tin as a constituent element are deposited between the substrate and the coating film. At this time, the coating film serves as a shielding plate for the base material, and the current density on the surface of the base material is reduced, so that the deposited particles have a small, dense and uniform shape. Subsequently, the particles are deposited along the negative electrode current collector 61 of the coating film and further deposited on the surface of the coating film. At this time, since the surface of the coating film has nothing to serve as a shielding plate, the current density is high and the deposited particles are also large.

  After forming the electrode reaction part 62, the electrode reaction part 62 is peeled off from the base material to complete the negative electrode 60 shown in FIG. Moreover, after forming the electrode reaction part 62, it is preferable to perform an annealing process similarly to 1st Embodiment. This is because at least part of the interface between the negative electrode current collector 61 and the electrode reaction part 62 can be alloyed. Further, the pressurizing process may be performed in the same manner as in the first embodiment. This is because the volume energy density can be improved and the contact between the negative electrode current collector 61 and the electrode reaction part 62 can be improved.

  For example, the negative electrode 60 is used in a secondary battery in the same manner as in the first embodiment, and functions similarly. That is, in this secondary battery, the electrode reaction part 62 greatly expands and contracts with charge / discharge, but the negative electrode current collector 61 is present inside the electrode reaction part 62, so that the negative electrode current collector 61 and the electrode reaction occur. The contact with the part 62 is maintained.

  As described above, according to the present embodiment, the particulate negative electrode current collector 61 is covered with the electrode reaction portion 62 so as to have the particulate negative electrode current collector 61 inside the electrode reaction portion 62. Therefore, the contact property between the negative electrode current collector 61 and the electrode reaction part 62 can be increased, and the decrease in the current collection property due to the expansion and contraction of the electrode reaction part 62 can be suppressed. Therefore, excellent cycle characteristics can be obtained. Further, the volume ratio of the current collector in the battery can be reduced, and the volume energy density can be improved.

  In particular, if the average particle diameter of the negative electrode current collector 61 is set in the range of 0.01 μm or more and 20 μm or less, a higher effect can be obtained.

  Furthermore, if the negative electrode current collector 61 and the electrode reaction part 62 are alloyed at least at a part of the interface, the contact property can be further improved.

  Further, specific embodiments of the present invention will be described in detail with reference to the drawings.

(Examples 1-1 to 1-4)
The negative electrode 10 shown in FIG. 1 was produced. First, tin particles having an average particle diameter of 1 μm are prepared as the negative electrode active material particles 11, polyvinylidene fluoride is mixed with the tin particles so as to be 10% by mass as a binder, and this mixture is a dispersion medium. The slurry was dispersed in N-methyl-2-pyrrolidone to obtain a slurry having an appropriate viscosity. The slurry was applied to the substrate 20 and dried to prepare a coating film 21. As the base material 20, a stainless steel foil having a thickness of 20 μm was used. Subsequently, the negative electrode current collector 12 was formed by coating the negative electrode active material particles 11 by plating copper on the base material 20 on which the coating film 21 was formed by a plating method. A plating solution having a pH of 0.5 was used for plating. After that, the base material 20 was peeled from the negative electrode current collector 12 coated with the negative electrode active material particles 11, washed with running water, and then vacuum-dried to produce the negative electrode 10. Furthermore, in Example 1-2, after vacuum drying, annealing is performed at 200 ° C. for 10 hours. In Example 1-3, after vacuum drying, pressure treatment is performed. In Example 1-4, vacuum is applied. After drying, an annealing treatment at 200 ° C. for 10 hours and a pressure treatment were performed.

  About the produced negative electrode 10, it cut out with the microtome and observed the cross section with the scanning electron microscope (Scanning Electron Microscope; SEM). FIG. 7 is a SEM photograph showing the cross-sectional configuration of the negative electrode 10, and FIG. 8 shows the cross-sectional configuration of FIG. 7 separated by hatching. Further, when the structure was examined by EDX (energy dispersive X-ray analyzer), in FIG. 8, the portion represented by the right underline is made of copper, and the portion represented by the right upper line is made of tin. confirmed. That is, it was found that tin particles were present inside copper.

  Moreover, about the negative electrode 10, when it produced, the surface of the surface side which was not contacting with the surface which was contacting the base material 20 was observed with the scanning electron microscope. FIG. 9 is an SEM photograph of the surface of the negative electrode 10 that was in contact with the base material 20, and FIG. 10 is an SEM photograph of the surface side surface that was not in contact. As can be seen from these SEM photographs, the surface that was in contact with the base material 20 had a smaller particle, a dense, and uniform shape than the surface that did not contact the surface.

  As Comparative Example 1-1 with respect to Examples 1-1 to 1-4, a slurry containing negative electrode active material particles produced in the same manner as in Examples 1-1 to 1-4 was prepared as a negative electrode collector made of copper foil having a thickness of 20 μm. The negative electrode was produced by applying to an electric body and drying.

  Moreover, as Comparative Example 1-2, a mixture in which tin particles having an average particle diameter of 1 μm as negative electrode active material particles and copper particles having an average particle diameter of 1 μm as a conductive material were mixed at a mass ratio of 1: 1. In addition, polyvinylidene fluoride as a binder is mixed so as to be 10% by mass, and this is dispersed in N-methyl-2-pyrrolidone as a dispersion medium to form a negative electrode current collector made of a copper foil having a thickness of 20 μm. The negative electrode was prepared by applying and drying.

  Furthermore, as Comparative Example 1-3, a slurry containing negative electrode active material particles produced in the same manner as in Examples 1-1 to 1-4 was applied to a negative electrode current collector made of a copper foil having a thickness of 20 μm and dried. Thereafter, copper particles having an average particle diameter of 1 μm as a conductive material and polyvinylidene fluoride as a binder are mixed on this so that the polyvinylidene fluoride becomes 10% by mass, and N is a dispersion medium. A negative electrode was prepared by applying a slurry dispersed in methyl-2-pyrrolidone and drying.

  In addition, as Comparative Example 1-4, a negative electrode was formed by forming a 1 μm thick tin film on the surface of a metal nonwoven fabric mainly composed of copper by an electroless plating method.

Subsequently, using the negative electrodes 10 of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-4, coin-type test batteries as shown in FIG. 3 were produced. The counter electrode is a lithium metal plate, a porous polyethylene film is used as the separator, and LiPF ₆ is mixed in a solvent in which ethylene carbonate and diethyl carbonate are mixed at a volume ratio of ethylene carbonate: diethyl carbonate = 1: 2 as the electrolyte. What was dissolved at a concentration of 1 mol / l was used.

For the produced test batteries of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-4, 50 cycles of charge / discharge were performed at a current density of 1 mA / cm ² , and discharge of the 50th cycle relative to the first cycle. The capacity ratio was determined as the discharge capacity maintenance rate. The results are shown in Table 1. For Comparative Example 1-1, the ratio of the discharge capacity at the 20th cycle to the first cycle is shown in Table 1.

  As can be seen from Table 1, according to Examples 1-1 to 1-4 in which the negative electrode current collector 12 was formed on the negative electrode active material particles 11 by plating, the negative electrode active material particles were formed on the surface of the foil-shaped negative electrode current collector. Compared with Comparative Examples 1-1 to 1-3, in which the negative electrode active material was plated on the surface of a negative electrode current collector made of nonwoven fabric, the discharge capacity retention rate was improved. Moreover, according to Examples 1-2 to 1-4 in which the annealing treatment or the pressure treatment was performed, the discharge capacity retention rate was further improved as compared with Example 1-1 in which these treatments were not performed. In Example 1-4 in which the annealing treatment and the pressure treatment were performed, a high value was obtained.

  That is, it was found that the cycle characteristics can be improved by having the negative electrode active material particles 11 inside the negative electrode current collector 12. Further, it has been found that higher effects can be obtained by forming the negative electrode current collector 12 and then performing an annealing process or a pressurizing process.

(Examples 2-1 to 2-6)
A negative electrode 10 and a test battery were produced in the same manner as in Example 1-1 except that the average particle diameter of the tin particles as the negative electrode active material particles 11 was changed in the range of 0.005 μm to 30 μm. For the fabricated secondary batteries of Examples 2-1 to 2-6, the discharge capacity retention ratio was determined in the same manner as in Examples 1-1 to 1-4. These results are shown in Table 2 together with the results of Example 1-1.

  As can be seen from Table 2, the discharge capacity retention rate increased as the average particle size of the tin particles increased, and decreased after showing a maximum value. That is, it was found that the average particle diameter of the negative electrode active material particles 11 is preferably in the range of 0.01 μm to 20 μm.

(Examples 3-1 to 3-9)
The negative electrode active material particles 11 are made of Sn—Zn alloy, Sn—Co alloy, Sn—Ag alloy, Sn—In alloy, Sn—Fe alloy, Sn—Cu alloy, Sn—Ni alloy, Sn—Pb alloy or Sn—Bi alloy. Except for the above, a negative electrode 10 and a test electrode were produced in the same manner as in Example 1-1. For the fabricated secondary batteries of Examples 3-1 to 3-9, the discharge capacity retention ratio was determined in the same manner as in Examples 1-1 to 1-4. These results are shown in Table 3 together with the results of Example 1-1.

  As can be seen from Table 3, in Examples 3-1 to 3-9 in which an alloy containing tin as a constituent element was used for the negative electrode active material particles 11 as in Example 1-1, a high discharge capacity retention rate was obtained. Obtained. That is, it was found that the same effect can be obtained even when other negative electrode active material particles 11 containing tin as a constituent element are used.

(Examples 4-1 to 4-3)
Except that the negative electrode active material particles 11 were coated to form the negative electrode current collector 12 by plating nickel, copper, or a Cu—Zn alloy by the plating method, and the others were the same as in Example 1-1. A negative electrode 10 and a test battery were produced. For the fabricated secondary batteries of Examples 4-1 to 4-3, the discharge capacity retention ratio was determined in the same manner as in Examples 1-1 to 1-4. These results are shown in Table 4 together with the results of Example 1-1.

  As can be seen from Table 4, in Examples 4-1 to 4-3 in which the negative electrode current collector 12 was formed by plating nickel, copper, or a Cu-Zn alloy, as in Example 1-1. A high discharge capacity retention rate was obtained. That is, it was found that the same effect can be obtained even if the negative electrode current collector 12 is made of another material.

(Examples 5-1 to 5-3)
As Examples 5-1 and 5-2, the secondary battery shown in FIG. 3 was produced using the negative electrode 10 produced in the same manner as in Example 1-1. At that time, the positive electrode 33 uses lithium cobalt oxide (LiCoO ₂ ) as a positive electrode active material, mixes lithium cobalt oxide, artificial graphite as a conductive material, and polyvinylidene fluoride as a binder, and N—is a dispersion medium. It was prepared by dispersing in methyl-2-pyrrolidone, applying to a positive electrode current collector made of aluminum foil and drying. A porous polyethylene film is used for the separator 34, and LiPF ₆ is dissolved at a concentration of 1 mol / l in a solvent in which ethylene carbonate and diethyl carbonate are mixed in a volume ratio of ethylene carbonate: diethyl carbonate = 1: 2 for the electrolyte. What was made to use was used.

  Moreover, in Example 5-1, it arrange | positions so that the surface of the side which was contacting the base material 20 when producing the negative electrode 10 may be made to oppose the positive electrode 33, and in Example 5-2, the negative electrode 10 is produced. At this time, the surface side surface not in contact with the base material was arranged to face the positive electrode 33.

Further, as Example 5-3, the secondary battery shown in FIGS. At that time, the positive electrode 44 was produced in the same manner as in Examples 5-1 and 5-2, and the separator 45 was also the same as in Examples 5-1 and 5-2. The electrolyte layer 46 includes an electrolyte solution in which LiPF ₆ is dissolved at a concentration of 1 mol / l in a solvent in which a copolymer of polyvinylidene fluoride and hexafluoropropylene, and ethylene carbonate and propylene carbonate are mixed in the same volume. Were mixed and applied to both surfaces of the positive electrode 44 and the negative electrode 10.

  About the produced secondary battery of Examples 5-1 to 5-3, it carried out similarly to Examples 1-1 to 1-4, and calculated | required the discharge capacity maintenance factor. The results are shown in Table 5.

  As can be seen from Table 5, even when any one or both surfaces of the negative electrode 10 were opposed to the positive electrodes 33 and 44, the same discharge capacity retention rate was obtained. That is, it has been found that the electrode reactant can be occluded and released equally on any surface of the negative electrode 10, and furthermore, equivalent cycle characteristics can be obtained.

(Examples 6-1 to 6-4)
The negative electrode 60 shown in FIG. 6 was produced. First, copper particles having an average particle diameter of 1 μm as the negative electrode current collector 61 and polyvinylidene fluoride as a binder are mixed so that the polyvinylidene fluoride is 10% by mass, and this mixture is mixed with a dispersion medium. Disperse in a certain N-methyl-2-pyrrolidone to make a slurry of suitable viscosity. This slurry was applied to a substrate and dried to prepare a coating film. A stainless foil having a thickness of 20 μm was used as the substrate. Then, the electrode reaction part 62 which coat | covered the negative electrode collector 61 was formed by plating tin which is a negative electrode active material by the plating method to the base material in which the coating film was formed. After that, the base material was peeled off from the electrode reaction part 62 coated with the negative electrode current collector 61, washed with running water, and then vacuum dried to prepare the negative electrode 60. In Example 6-2, after vacuum drying, annealing is performed at 200 ° C. for 10 hours. In Example 6-3, after vacuum drying, pressurization is performed. In Example 6-4, vacuum drying is performed. After that, annealing treatment at 200 ° C. for 10 hours and pressure treatment were performed.

  About the produced negative electrode 60, it cut out with the microtome and observed the cross section by SEM. FIG. 11 is an SEM photograph showing the cross-sectional configuration of the negative electrode 60, and FIG. 12 shows the cross-sectional configuration of FIG. 11 separated by hatching. Moreover, when the structure was investigated by EDX, in FIG. 12, it was confirmed that the part represented by the upper right oblique line is made of tin, and the part represented by the lower right oblique line is made of copper. That is, it was found that copper particles were present inside tin.

  Moreover, about the negative electrode 60, the surface of the surface side which was not contacting with the surface which was contacting the base material when produced was observed with the scanning electron microscope. FIG. 13 is a SEM photograph of the surface of the negative electrode 60 that was in contact with the base material, and FIG. 14 is a SEM photograph of the surface side surface that was not in contact. As can be seen from these SEM photographs, the surface that was in contact with the base material had a smaller particle, a dense and uniform shape than the surface on the surface side that was not in contact.

  Test batteries were produced using this negative electrode 60 in the same manner as in Examples 1-1 to 1-4. For the obtained test batteries of Examples 6-1 to 6-4, the discharge capacity retention ratio was determined in the same manner as in Examples 1-1 to 1-4. The results are shown in Table 6 together with the results of Comparative Examples 1-1 to 1-4.

  As can be seen from Table 6, according to Examples 6-1 to 6-4 in which the electrode reaction part 62 was formed on the particulate negative electrode current collector 61 by plating, compared with Comparative Examples 1-1 to 1-4. The discharge capacity maintenance rate was improved. In addition, according to Examples 6-2 to 6-4 in which annealing treatment or pressure treatment was performed, the discharge capacity retention rate was further improved as compared with Example 6-1 in which these treatments were not performed. In Example 6-4 in which the annealing treatment and the pressure treatment were performed, a high value was obtained.

  In other words, it was found that the cycle characteristics can be improved by having the particulate negative electrode current collector 61 inside the electrode reaction part 62. Further, it has been found that if an annealing process or a pressurizing process is performed after the electrode reaction part 62 is formed, a higher effect can be obtained.

(Examples 7-1 to 7-6)
A negative electrode 60 and a test battery were produced in the same manner as in Example 6-1, except that the average particle diameter of the copper particles as the negative electrode current collector 61 was changed within the range of 0.005 μm to 30 μm. For the fabricated secondary batteries of Examples 7-1 to 7-6, the discharge capacity retention ratio was determined in the same manner as in Examples 1-1 to 1-4. These results are shown in Table 7 together with the results of Example 6-1.

  As can be seen from Table 7, the discharge capacity retention rate increased as the average particle size of the copper particles increased, and decreased after showing a maximum value. That is, it was found that the average particle size of the negative electrode current collector 61 is preferably in the range of 0.01 μm to 20 μm.

(Examples 8-1 to 8-9)
The metal used for plating is Sn—Zn alloy, Sn—Co alloy, Sn—Ag alloy, Sn—In alloy, Sn—Fe alloy, Sn—Cu alloy, Sn—Ni alloy, Sn—Pb alloy or Sn—Bi alloy. A negative electrode 60 and a test electrode were produced in the same manner as in Example 6-1 except that the replacement was performed. For the fabricated secondary batteries of Examples 8-1 to 8-9, the discharge capacity retention ratio was determined in the same manner as in Examples 1-1 to 1-4. These results are shown in Table 8 together with the results of Example 6-1.

  As can be seen from Table 8, similarly to Example 6-1, high discharge capacity retention ratios were obtained in Examples 8-1 to 8-9 using alloys containing Sn as a constituent element in the metal used for plating. It was. That is, it has been found that the same effect can be obtained even if the electrode reaction part 62 is constituted by another negative electrode active material containing tin as a constituent element.

(Examples 9-1 to 9-3)
A secondary battery was made in the same manner as in Examples 5-1 to 5-3, except that the negative electrode 60 produced in Example 6-1 was used. For the fabricated secondary batteries of Examples 9-1 to 9-3, the discharge capacity retention ratio was determined in the same manner as in Examples 1-1 to 1-4. These results are shown in Table 9.

  As can be seen from Table 9, even when any one or both surfaces of the negative electrode 60 were opposed to the positive electrodes 33 and 44, the same discharge capacity retention rate was obtained. In other words, it was found that the electrode reactants can be occluded and released equally on any surface of the negative electrode 60, and equivalent cycle characteristics can be obtained.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, the case where an electrolytic solution which is a liquid electrolyte or a so-called gel electrolyte is used has been described, but another electrolyte may be used. Examples of other electrolytes include solid electrolytes having ionic conductivity, a mixture of a solid electrolyte and an electrolyte solution, and a mixture of a solid electrolyte and a gel electrolyte.

  As the solid electrolyte, for example, a polymer solid electrolyte in which an electrolyte salt is dispersed in a polymer compound having ion conductivity, or an inorganic solid electrolyte made of ion conductive glass or ionic crystals can be used. Examples of the polymer compound of the solid polymer electrolyte include, for example, an ether polymer compound such as polyethylene oxide or a crosslinked product containing polyethylene oxide, an ester polymer compound such as polymethacrylate, and an acrylate polymer compound. Or can be copolymerized. In addition, as the inorganic solid electrolyte, one containing lithium nitride or lithium phosphate can be used.

  In the above embodiments and examples, a coin type or wound laminate type secondary battery has been described. However, the present invention is not limited to a cylindrical type, a square type, a button type, a thin type, a large size, or a laminated laminate type. The present invention can be similarly applied to a secondary battery having the shape. In addition, the present invention can be applied not only to secondary batteries but also to primary batteries.

It is sectional drawing showing the structure of the negative electrode which concerns on the 1st Embodiment of this invention. It is explanatory drawing showing the manufacturing process of the negative electrode shown in FIG. It is sectional drawing showing the structure of the secondary battery using the negative electrode shown in FIG. It is a disassembled perspective view showing the structure of the other secondary battery using the negative electrode shown in FIG. FIG. 5 is a cross-sectional view illustrating a structure taken along line II of the secondary battery illustrated in FIG. 4. It is sectional drawing showing the structure of the negative electrode which concerns on the 2nd Embodiment of this invention. It is a SEM photograph showing the cross-sectional structure of the negative electrode produced in the Example of this invention. FIG. 8 is an explanatory diagram showing the cross-sectional configuration shown in FIG. 7 by hatching. It is a SEM photograph showing the surface structure of the negative electrode produced in the Example of this invention. It is another SEM photograph showing the surface structure of the negative electrode produced in the Example of this invention. It is a SEM photograph showing the cross-sectional structure of the negative electrode produced in the other Example of this invention. FIG. 12 is an explanatory diagram illustrating the cross-sectional configuration illustrated in FIG. 11 by hatching. It is another SEM photograph showing the surface structure of the negative electrode produced in the Example of this invention. It is another SEM photograph showing the surface structure of the negative electrode produced in the Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,60 ... Negative electrode, 11 ... Negative electrode active material particle | grains, 12, 61 ... Negative electrode collector, 12A ... Particle | grains, 20 ... Base material, 21 ... Coating film, 31 ... Outer cup, 32 ... Outer can, 33, 44 ... Positive electrode, 33A, 44A ... Positive electrode current collector, 33B, 44B ... Positive electrode active material layer, 34, 45 ... Separator, 35 ... Gasket, 40 ... Electrode wound body, 41 ... Positive electrode lead, 42 ... Negative electrode lead, 43 ... Adhesion Film, 46 ... electrolyte layer, 47 ... protective tape, 50 ... exterior member, 62 ... electrode reaction part.

Claims (32)

Negative electrode active material particles containing tin as a constituent element;
And a negative electrode current collector having the negative electrode active material particles therein.   2. The negative electrode according to claim 1, wherein an average particle diameter of the negative electrode active material particles is in a range of 0.01 μm to 20 μm.   The negative electrode according to claim 1, wherein the negative electrode current collector includes at least one selected from the group consisting of copper, nickel, iron, and alloys thereof.   The negative electrode according to claim 1, wherein the negative electrode active material particles and the negative electrode current collector are alloyed at least at a part of the interface. Negative electrode active material particles containing tin as a constituent element;
And a negative electrode current collector formed by plating so as to cover the negative electrode active material particles. A particulate negative electrode current collector;
A negative electrode having the negative electrode current collector inside and an electrode reaction part containing tin as a constituent element.   The negative electrode according to claim 6, wherein an average particle diameter of the negative electrode current collector is in a range of 0.01 μm to 20 μm.   The negative electrode according to claim 6, wherein the negative electrode current collector includes at least one selected from the group consisting of copper, nickel, iron, and alloys thereof.   The negative electrode according to claim 6, wherein the negative electrode current collector and the electrode reaction part are alloyed at least at a part of the interface. A particulate negative electrode current collector;
And an electrode reaction part containing tin as a constituent element formed by plating so as to cover the negative electrode current collector. A battery comprising an electrolyte together with a positive electrode and a negative electrode,
The negative electrode has negative electrode active material particles containing tin as a constituent element, and a negative electrode current collector having the negative electrode active material particles therein.   The battery according to claim 11, wherein an average particle size of the negative electrode active material particles is in a range of 0.01 μm to 20 μm.   The battery according to claim 11, wherein the negative electrode current collector includes at least one selected from the group consisting of copper, nickel, iron, and alloys thereof.   The battery according to claim 11, wherein the negative electrode active material particles and the negative electrode current collector are alloyed at least at a part of the interface. A battery comprising an electrolyte together with a positive electrode and a negative electrode,
The negative electrode has negative electrode active material particles containing tin as a constituent element, and a negative electrode current collector formed by plating so as to cover the negative electrode active material particles. A battery comprising an electrolyte together with a positive electrode and a negative electrode,
The negative electrode has a particulate negative electrode current collector, and an electrode reaction part that has the negative electrode current collector therein and contains tin as a constituent element.   The battery according to claim 16, wherein the negative electrode current collector has an average particle diameter in the range of 0.01 μm to 20 μm.   The battery according to claim 16, wherein the negative electrode current collector includes at least one selected from the group consisting of copper, nickel, iron, and alloys thereof.   The battery according to claim 16, wherein the negative electrode current collector and the electrode reaction part are alloyed at least at a part of the interface. A battery comprising an electrolyte together with a positive electrode and a negative electrode,
The negative electrode has a particulate negative electrode current collector, and an electrode reaction part containing tin as a constituent element formed by plating so as to cover the negative electrode current collector. A step of supporting negative electrode active material particles containing tin as a constituent element on a base material, and forming a negative electrode current collector so as to cover the negative electrode active material particles by plating;
Forming a negative electrode current collector, and then peeling the substrate.   The method for producing a negative electrode according to claim 21, wherein the average particle diameter of the negative electrode active material particles is in the range of 0.01 µm to 20 µm.   The method of manufacturing a negative electrode according to claim 21, wherein the negative electrode current collector is formed of at least one selected from the group consisting of copper, nickel, iron, and alloys thereof.   The method for producing a negative electrode according to claim 21, further comprising a step of performing at least one of annealing and pressing after forming the negative electrode current collector.   The method for producing a negative electrode according to claim 21, wherein the substrate is formed of at least one selected from the group consisting of a metal material and a resin material. Forming a negative electrode current collector on a substrate and forming an electrode reaction part containing tin as a constituent element so as to cover the negative electrode current collector by plating; and
And a step of peeling the substrate after forming the electrode reaction part.   27. The method for producing a negative electrode according to claim 26, wherein an average particle size of the negative electrode current collector is in a range of 0.01 [mu] m to 20 [mu] m.   27. The method for manufacturing a negative electrode according to claim 26, wherein the negative electrode current collector is formed of at least one selected from the group consisting of copper, nickel, iron, and alloys thereof.   27. The method for producing a negative electrode according to claim 26, further comprising a step of performing at least one of an annealing process and a pressurizing process after forming the electrode reaction part.   27. The method for manufacturing a negative electrode according to claim 26, wherein the substrate is formed of at least one selected from the group consisting of a metal material and a resin material. A method for producing a battery comprising an electrolyte together with a positive electrode and a negative electrode,
The negative electrode is formed by supporting negative electrode active material particles containing tin as a constituent element on a base material, forming a negative electrode current collector so as to cover the negative electrode active material particles by plating, and then peeling the base material. A method for producing a battery, comprising: forming a battery. A method for producing a battery comprising an electrolyte together with a positive electrode and a negative electrode,
The negative electrode carries a particulate negative electrode current collector on a base material, forms an electrode reaction part containing tin as a constituent element so as to cover the negative electrode current collector by plating, and then peels the base material A method for producing a battery, characterized by comprising:

Images